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  • 1995-1999  (485)
  • 1980-1984
  • 1996  (485)
  • Atomic, Molecular and Optical Physics  (433)
  • Nuclear reactions
  • Ultrastructure
  • 1
    Electronic Resource
    Electronic Resource
    Effects of long-term open-air exposure to fluoride, nitrogen compounds and SO2 on visible symptoms, pollutant accumulation and ultrastructure of Scots pine and Norway spruce seedlings (1996)
    Springer
    Trees 10 (1996), S. 157-171 
    Details
    ISSN: 1432-2285
    Keywords: Conifer ; Fluoride ; Nitrogen ; Sulphur dioxide ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effects of SO2, aqueous fluoride (NaF) and a solution of nitrogen compounds (NH4NO3) on the visible symptoms, pollutant accumulation and ultrastructure of Scots pine (Pinus sylvestris L.) and Norway spruce [Picea abies (L.) Karst.] seedlings were studied in an open-air experiment lasting for 3 consecutive years. Visible injury symptoms were most pronounced in combination exposures and whenever F was applied. Visible symptoms correlated well with needle pollutant concentrations. Exposure to NaF increased needle F contents particularly when F was applied with SO2 or NH4NO3. This suggests that a reduction in N or SO2 emissions, in F polluted areas, could improve the condition of conifers via decreased accumulation of phytotoxic F in the needles. Norway spruce needles accumulated 2–10 times as much S and F as those of Scots pine. Microscopic observations showed various changes in the needle mesophyll cell ultrastructure. In both species, exposure to SO2 increased significantly the amount of cytoplasmic vacuoles, suggesting detoxification of excess sulphate or low pH. F treatments resulted in a significant enlargement of plastoglobuli in Scots pine and a darkening of plastoglobuli in Norway spruce. All exposures enhanced the accumulation of lipid bodies. An increased portion of translucent plastoglobuli was most pronounced in N treatments. Many of the ultrastructural changes and visible symptoms appeared only as number of years exposed increased, indicating that long-term experiments are needed. Both visible symptoms and ultrastructural changes pointed to the more pronounced sensitivity of Norway spruce compared to Scots pine. Ultrastructural results mostly supported earlier qualitative observations of F, N and SO2 effects on needle mesophyll cell ultrastructure. However, no reduction of thylakoids in SO2 containing exposure or curling of thylakoids in F exposure could be detected in the present study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02340767
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  • 2
    Electronic Resource
    Electronic Resource
    Ultrastructure of multinucleated giant cell apoptosis in foreign-body granuloma (1996)
    Springer
    Virchows Archiv 428 (1996), S. 165-176 
    Details
    ISSN: 1432-2307
    Keywords: Foreign-body giant cells ; Granulation tissue ; Apoptosis ; Ultrastructure ; p53 expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To elucidate the role of apoptosis in the disappearance of multinucleated giant cells from the granulation tissue in cases of foreign-body granuloma, we induced a foreign-body reaction by implanting a collagen sponge into the dorsum of the rat and observed apoptotic changes within the multinucleated giant cells using electron microscopy. Two types of multinucleated giant cells were identified presenting apoptotic characteristics morphologically. One was characterized by apoptosis of only one nucleus, followed by cytoplasmic changes, rupture of the plasma membrane and necrosis evoking an inflammatory reaction. The other showed typical apoptotic changes in the majority or in all of the nuclei, followed by phagocytosis of the apoptotic syncytia. The results of the present study suggest that apoptosis occurring within only one nucleus might be triggered by overexpression of the p53 protein, because DNA abnormalities are confined to this single nucleus. In contrast apoptosis occurring simultaneously in the majority or all of the nuclei is most probably due to cell death caused by senescence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00200659
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  • 3
    Electronic Resource
    Electronic Resource
    Quantitative analysis of ultrastructural changes during zygotic and somatic embryogenesis in pearl millet (Pennisetum glaucum [L.] R. Br.) (1996)
    Springer
    Sexual plant reproduction 9 (1996), S. 286-298 
    Details
    ISSN: 1432-2145
    Keywords: Key words Somatic embryogenesis ; Ultrastructure ; Pennisetum ; Poaceae ; Morphometrics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Ultrastructural changes during zygotic and somatic embryogenesis in pearl millet (Pennisetum glaucum [L.] R. Br.) were quantified using morphometric techniques. The total area per cell profile and the cell volume percentage of the whole cell, endoplasmic reticulum (ER), Golgi bodies, mitochondria, nuclei, lipids, plastids, starch grains and vacuoles were measured and comparisons made between three zygotic and three somatic embryo developmental stages. All measurements were taken from scutellar or scutellar-derived cells. Zygotic embryogenesis was characterized by increases in cell size, lipids, plastids, starch, Golgi bodies, mitochondria and ER. Somatic embryogenesis was characterized by two phases of cell development: (1) the dedifferentiation of scutellar cells involving a reduction in cell and vacuole size and an increase in cell activity during somatic proembryoid formation and (2) the development of somatic embryos in which most cell organelle quantities returned to values found in late coleoptile or mature predesiccation zygotic stages. In summary, although their developmental pathways differed, the scutella of somatic embryos displayed cellular variations which were within the ranges observed for later stages of zygotic embryogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050045
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  • 4
    Electronic Resource
    Electronic Resource
    Fine structural changes of muscle spindles in the gracile axonal dystrophy mutant mouse (1996)
    Springer
    Virchows Archiv 428 (1996), S. 289-296 
    Details
    ISSN: 1432-2307
    Keywords: Mutant mouse ; Axonal degeneration ; Dying back process ; Muscle spindles ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Fine structural changes of muscle spindles in the extensor digitorum longus of the gracile axonal dystrophy mutant mouse were studied from 20 to 120 postnatal days. Degenerative nerve endings in muscle spindles were first recognized at 20 postnatal days. The sensory nerve endings were usually swollen with decrease of cell organelles, and the cytoplasm was electron-lucent. At 50 postnatal days, atrophic nerve endings were frequently observed in the narrow spaces between the indented cell membrane of intrafusal muscle cells and the basement membrane. In addition to degenerative and atrophic changes, regenerative axons showing fine sprouts (with or without Schwann cell projections) appeared in the sensory nerve endings at this time. At 80 postnatal days, sensory nerve endings frequently showed dystrophic changes characterized by axonal dilatation with accumulations of neurofilaments, tubulovesicular structures, mitochondria and myelin-like figures. These findings suggest that axonal transport in the sensory nerve endings is impaired in this mutant mouse. Motor nerve endings were usually well preserved and normal structures even at 80 postnatal days. Intrafusal fibrosis, decrease in number of sensory nerve endings and atrophy of intrafusal muscle fibres were clearly recognized by 100 days of age.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196703
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  • 5
    Electronic Resource
    Electronic Resource
    Epithelioid angiosarcoma of the thyroid (1996)
    Springer
    Virchows Archiv 429 (1996), S. 131-137 
    Details
    ISSN: 1432-2307
    Keywords: Thyroid ; Angiosarcoma ; Immunohistochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Epithelioid angiosarcomas of the thyroid usually develop in people living in Alpine regions, and only rare cases arising in subjects living in nonmountainous areas have been reported. We describe the clinicopathological features of a series of seven cases collected from non-Alpine areas. All patients were adults. The tumours appeared as haemorrhagic, unencapsulated, sometimes cystic nodules. In two cases multinodularity was present. They were composed of large, epithelioid cells, which lined vascular-like spaces or were arranged in solid sheets. Intracytoplasmic lumina containing red blood cells were identified. Neoplastic cells were diffusely positive for factor VIII-related antigen, Ulex europaeus agglutinin, CD31 and keratin peptides. Ultrastructural studies were performed in four cases and showed features of endothelial differentiation. An average follow-up of 3.8 years disclosed that four patients died of disease after a median survival time of 5 months, whereas 3 patients are still alive with no evidence or residual disease 27, 32 and 66 months after thyroidectomy. The good prognosis in these patients appears to be related mainly to the absence of extraglandular tumour spread at the time of surgery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192435
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  • 6
    Electronic Resource
    Electronic Resource
    Tacrolimus (FK 506) biotransformation in primary rat hepatocytes depends on extracellular matrix geometry (1996)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 353 (1996), S. 461-473 
    Details
    ISSN: 1432-1912
    Keywords: Hepatocytes ; Sandwich culture ; Ultrastructure ; Morphology ; Sirolimus ; Tacrolimus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Established in vitro models for studies of hepatic drug biotransformation include the use of primary hepatocytes. In normal liver the space of Disse provides the possibility of bilateral attachment to extracellular matrix for each hepatocyte. This configuration is disrupted by the cell isolation procedure of normal liver tissue, which delivers suspensions of round shaped cells. In standard culture configurations this unphysiologic cell shape terminates in a morphological dedifferentiation and inability to biotransform drugs. This study analyses the relevance of extracellular matrix geometry in hepatocyte monolayer configurations for expression and activity of cytochrome P450 3A. This enzyme is involved in the biotransformation of a large number of pharmaceuticals including the immunosuppressants tacrolimus and sirolimus. Morphological analysis of primary rat hepatocytes cultured with and without overlay of collagen type I was performed by transmission and scanning electron microscopy. Expression and activity of cytochrome P450 3A was studied by Western blot and the use of two model drugs specific for this enzyme. To this purpose the immunosuppressive drugs tacrolimus and sirolimus were used. Metabolites were analyzed by HPLC and HPLGMS. Two sided attachment to extracellular matrix induces profound changes of the hepatocellular morphology in vitro resulting in the reconstitution of a polyhedric cell shape. This phenomenon is paralleled by an enhanced expression of cytochrome P450 3A and corresponding metabolic activity. As shown for tacrolimus biotransformation, the model may be useful to study complex metabolic patterns. In addition this model may facilitate studies of the kinetics of hepatocellular drug biotransformation in a setting with prolonged stability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261444
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  • 7
    Electronic Resource
    Electronic Resource
    Tacrolimus (FK 506) biotransformation in primary rat hepatocytes depends on extracellular matrix geometry (1996)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 353 (1996), S. 461-473 
    Details
    ISSN: 1432-1912
    Keywords: Key words Hepatocytes ; Sandwich culture ; Ultrastructure ; Morphology ; Sirolimus ; Tacrolimus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Established in vitro models for studies of hepatic drug biotransformation include the use of primary hepatocytes. In normal liver the space of Disse provides the possibility of bilateral attachment to extracellular matrix for each hepatocyte. This configuration is disrupted by the cell isolation procedure of normal liver tissue, which delivers suspensions of round shaped cells. In standard culture configurations this unphysiologic cell shape terminates in a morphological dedifferentiation and inability to biotransform drugs. This study analyses the relevance of extracellular matrix geometry in hepatocyte monolayer configurations for expression and activity of cytochrome P450 3A. This enzyme is involved in the biotransformation of a large number of pharmaceuticals including the immunosuppressants tacrolimus and sirolimus. Morphological analysis of primary rat hepatocytes cultured with and without overlay of collagen type I was performed by transmission and scanning electron microscopy. Expression and activity of cytochrome P450 3A was studied by Western blot and the use of two model drugs specific for this enzyme. To this purpose the immunosuppressive drugs tacrolimus and sirolimus were used. Metabolites were analyzed by HPLC and HPLC/MS. Two sided attachment to extracellular matrix induces profound changes of the hepatocellular morphology in vitro resulting in the reconstitution of a polyhedric cell shape. This phenomenon is paralleled by an enhanced expression of cytochrome P450 3A and corresponding metabolic activity. As shown for tacrolimus biotransformation, the model may be useful to study complex metabolic patterns. In addition this model may facilitate studies of the kinetics of hepatocellular drug biotransformation in a setting with prolonged stability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261444
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  • 8
    Electronic Resource
    Electronic Resource
    Visualization of crystal-matrix structure. In situ demineralization of mineralized turkey leg tendon and bone (1996)
    Springer
    Calcified tissue international 59 (1996), S. 474-479 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Apatite ; Collagen ; Demineralization ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract A technique to correlate the ultrastructural distribution of mineral with its organic material in identical sections of mineralized turkey leg tendon (MTLT) and human bone was developed. Osmium or ethanol fixed tissues were processed for transmission electron microscopy (TEM). The mineralized tissues were photographed at high, intermediate, and low magnifications, making note of section features such as fibril geometry, colloidal gold distribution, or section artifacts for subsequent specimen realignment after demineralization. The specimen holder was removed from the microscope, the tissue section demineralized in situ with a drop of 1 N HCl, then stained with 2% aqueous vanadyl sulfate. The specimen holder was reinserted into the microscope, realigned with the aid of the section features previously noted, and rephotographed at identical magnification used for the mineralized sections. A one to one correspondence was apparent between the mineral and its demineralized crystal “ghost” in both MTLT and bone. The fine structural periodic banding seen in unmineralized collagen was not observed in areas that were fully mineralized before demineralization, indicating that the axial arrangement of the collagen molecules is altered significantly during mineralization. Regions that had contained extrafibrillar crystallites stained more intensely than the intrafibrillar regions, indicating that the noncollagenous material surrounded the collagen fibrils. The methodology described here may have utility in determining the spatial distribution of the noncollagenous proteins in bone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369213
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  • 9
    Electronic Resource
    Electronic Resource
    Early ultrastructural changes after brief histotoxic hypoxia in cultured cortical and hippocampal CA1 neurons (1996)
    Springer
    Acta neuropathologica 92 (1996), S. 541-544 
    Details
    ISSN: 1432-0533
    Keywords: Key words Neuronal cultures ; Iodoacetate ; Histotoxic ; hypoxia ; Ribosomes ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Primary cortical and hippocampal neuronal cultures submitted to brief histotoxic hypoxia suffer delayed neuronal death after 24 h [Uto et al. (1995) J Neurochem 64: 2185–2192]. In this study the ultrastructural changes were monitored during the first 6 h following 5-min histotoxic hypoxia induced by exposure to 100 μM iodoacetate. In both cortical and hippocampal CA1 neurons, disaggregation of ribosomes was the earliest sign of histotoxic pathology. Vacuolizations of mitochondria, endoplasmic reticulum and Golgi apparatus, as well as fragmentation and disintegration of neurofilaments followed later. Signs of apoptotic nuclear degeneration were absent. Our observations demonstrate that, similar to that seen in ischemia, disaggregation of ribosomes after brief histotoxic hypoxia is one of the first pathological alterations heralding delayed neuronal death.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050559
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  • 10
    Electronic Resource
    Electronic Resource
    The microvascular system in ischemic cortical lesions (1996)
    Springer
    Acta neuropathologica 92 (1996), S. 56-63 
    Details
    ISSN: 1432-0533
    Keywords: Key words Brain ; Ultrastructure ; Vascular cast ; Scanning electron microscopy ; Microvasculature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the rat, normal blood flow can be restored in the territory of the occluded artery after an arterial occlusion. This event has been attributed to changes in the collateral vessels supplying the territory of the occluded artery. Since only a limited amount of data is available about the plasticity of the microvascular system after a cortical ischemic lesion, in the present study we have evaluated whether the restoration of blood flow to normal levels in the territory of the middle cerebral artery after permanent ischemia is due only to flow through preexisting collateral vessels or also to the development of new microvessels. Middle cerebral artery occlusion was performed in 45 rats. After 24 h of ischemia, magnetic resonance imaging was used to select 16 rats with cortical lesions of similar size and location. After 2 weeks, vascular corrosion casts were obtained from 8 rats by injection of low-viscosity resin and observed by scanning electron microscopy. A correlative light and electron microscopy study was performed using the remaining 8 rats. Two different patterns of vascular modifications were found, one dorsal and one ventral to the lesion. The dorsal portion of the lesion was vascularized by collateral arteries originating from the anterior or posterior cerebral arteries. Collateral trunks showed a meandering course, mainly in the occipital pole. In the ventral portion of the lesion a complex microvascular system was found characterized by an intense vascular proliferation. The arterioles showed a parallel, candelabrum-like pattern with dichotomic branching. Contraction rings were frequently seen. The capillaries showed a sinusoid-like structure, with a large lumen and a continuous endothelium with many micropinocytotic vesicles. A peripheral ring-shaped venous sinus was composed of a network of flat vessels. These results give the first comprehensive description of the microvascular modifications in a focal model of infarct and suggest that the restoration of blood flow to normal levels described in the territory of the middle cerebral artery after permanent ischemia may be due not only to flow through collateral vessels but also to the development of a new vascular system originating mainly from branches of the middle cerebral artery before the occlusion point.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050489
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  • 11
    Electronic Resource
    Electronic Resource
    Ultrastructural consequences of radical damage before and after differentiation of neuroblastoma B-104 cells (1996)
    Springer
    Acta neuropathologica 92 (1996), S. 75-89 
    Details
    ISSN: 1432-0533
    Keywords: Key words Radicals ; Neuron ; Ultrastructure ; Differentiation ; Golgi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract There is abundant evidence that the pathophysiology leading to neuronal death during post-ischemic brain reperfusion involves radical-mediated damage. Although the ultrastructural alterations accompanying brain ischemia and reperfusion are well characterized, little is known about the ultrastructural alterations that are specific to radical damage. This study examines in differentiated and undifferentiated neuroblastoma B-104 cells the viability (by dye exclusion) and ultrastructural consequences of radical damage initiated by 50 μM cumene hydroperoxide (CumOOH). Differentiation was most notably associated with formation of neurites and an extensive cytoskeletal feltwork. CumOOH-induced cell death was increased after differentiation and was blocked by the iron chelator DETAPAC. The ultrastructural characteristics of radical damage here included: (1) plasmalemmal holes that appear to undergo “patching” by well-organized membrane whorls, (2) accumulation of numerous free ribosomes, (3) markedly increased vesicular trafficking about the Golgi accompanied by Golgi transformation from cisternal organization to clusters of vacuoles with numerous fusing vesicles, (4) development of large multi-layered vacuoles that include damage membranes and organelles and appear to undergo extrusion from the cell, and (5) a general loss of cytoplasmic volume. These ultrastructural alterations developed more rapidly and were consistently more advanced in differentiated cells throughout the 6-h time course. In differentiated cells radical damage also induced the disorganization and subsequent loss of the extensive feltwork of cytoskeletal elements. There was little damage to the membranes of the nuclear envelope and mitochondria. Our observations in this system are strikingly similar to ultrastructural alterations in Golgi and ribosomal organization seen in vulnerable neurons during post-ischemic brain reperfusion and suggest that these alterations during reperfusion reflect the consequence of radical-mediated damage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050492
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  • 12
    Electronic Resource
    Electronic Resource
    Characterization of the interstitial cells associated with the submuscular plexus of the guinea-pig colon (1996)
    Springer
    Anatomy and embryology 194 (1996), S. 49-55 
    Details
    ISSN: 1432-0568
    Keywords: Pacemaker ; Interstitial cells of Cajal ; Intestine ; Ultrastructure ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Interstitial cells associated with the submuscular plexus of the guinea pig colon were studied by electron microscopy and by light microscopic wholemount stretch preparations. Their cytoplasmic features are similar to those of fibroblasts and they contain a well-developed Golgi apparatus, granular endoplasmic reticulum and many mitochondria. Intermediate filaments are abundantly distributed throughout the perinuclear region and processes. Numerous caveolae, a basal lamina and subsurface cisterns are observed on the cell membrane as in smooth muscle cells. The most characteristic feature of this cell type is the existence of many large gap junctions that interconnect these cells to each other and with the smooth muscle cells. Nerve varicosities containing synaptic vesicles are observed in close apposition with cells of this type. Whole-mount preparations stained by the zinc iodide-osmic acid method and by vimentin immunohistochemistry clearly demonstrated the stellate form of these gap junction-rich cells and suggested that they correspond to the interstitial cells of Cajal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196314
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  • 13
    Electronic Resource
    Electronic Resource
    Synaptic loss in anterior horn neurons in lower motor neuron disease (1996)
    Springer
    Acta neuropathologica 91 (1996), S. 416-421 
    Details
    ISSN: 1432-0533
    Keywords: Key words Motor neuron disease ; Anterior horn ; neuron ; Synapse ; Active zone ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This report concerns an ultrastructural investigation of the synapses of anterior horn neurons in the lumbar spinal cord of four patients with lower motor neuron disease (LMND) who had no upper motor neuron and corticospinal tract involvement. Anterior horn neurons of five normal individuals served as controls. The cell body area and the number of synapses of the normal-appearing neurons of the LMND patients were significantly reduced (P 〈 0.0001). These findings suggest that synaptic changes of anterior horn neurons could be ascribed to the degeneration of lower motor neurons rather than to the influence of upper motor neuron system degeneration. On the other hand, the lengths of individual synapses (P 〈 0.0001) and of their active zones (P 〈 0.05) were significantly increased in the patients. These increases would indicate that synapses on anterior horn neurons of individuals with LMND appear to have the capacity to react to progressive degeneration and loss of other synapses by means of a compensatory response or plasticity that enhances their efficiency.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050444
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  • 14
    Electronic Resource
    Electronic Resource
    Rattan bamboo blind (Japanese sudare)-like profiles of neurofibrillary tangles in Alzheimer’s disease (1996)
    Springer
    Acta neuropathologica 91 (1996), S. 448-450 
    Details
    ISSN: 1432-0533
    Keywords: Key words Neurofibrillary tangles ; Alzheimer’s ; disease ; Ultrastructure ; Rattan bamboo blind-like ; arrangement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An unusual ultrastructure for neurofibrillary tangles, which has not been described so far, is presented in a case of Alzheimer’s disease. This profile consists of parallelly arranged paired helical filaments and criss-cross tubular profiles that are arranged at regular interval of 300–500 nm, resembling rattan bamboo blind or Japanese sudare-like profiles. Coexistence of Hirano bodies in the same neuron is infrequently encountered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050451
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  • 15
    Electronic Resource
    Electronic Resource
    Synaptic organization of afferent projections to the supramammillary nucleus of the rat (1996)
    Springer
    Anatomy and embryology 193 (1996), S. 249-257 
    Details
    ISSN: 1432-0568
    Keywords: WGA-HRP ; anterograde tracing ; Ultrastructure ; Preoptic area ; Nucleus of diagonal band ; Laterodorsal tegmental nucleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We studied the fine structure of afferent terminals from the preoptic area, the nucleus of the diagonal band of Broca, the infralimbic cortex and the laterodorsal tegmental nucleus within the supramammillary nucleus (SUM) using the anterograde tracing method of horse-radish peroxidase conjugated with wheat germ agglutinin (WGA-HRP). Injection of WGA-HRP into the preoptic area permitted ultrastructural recognition of many anterogradely labeled terminals in the SUM. Almost all labeled terminals (99%) contained clear round synaptic vesicles and formed asymmetric synaptic contacts (Gray's type I). About 86% of labeled terminals from the nucleus of the diagonal band were asymmetric (Gray's type I), whereas 14% contained pleomorphic synaptic vesicles and formed symmetric synaptic contacts (Gray's type II). Almost all labeled terminals from the infralimbic cortex were located in the ventral part of the SUM, and 95% of labeled terminals were Gray's type I. The majority of labeled terminals (90%) from the laterodorsal tegmental nucleus were Gray's type I, and the remaining (10%) were Gray's type II. The percentage of labeled terminals with dense-cored vesicles was very high in terminals from the preoptic area (70%), and low in terminals from the infralimbic cortex (19%). Labeled terminals in all cases contacted mainly intermediate-sized dendrites (0.5–1.0 μm diameter). All cases had only a few labeled axosomatic terminals. The cases of injections into the preoptic area and the diagonal band nucleus had some reciprocal connections at the ultrastructural level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198328
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  • 16
    Electronic Resource
    Electronic Resource
    Tectorial membrane-organ of Corti relationship during cochlear development (1996)
    Springer
    Anatomy and embryology 194 (1996), S. 501-514 
    Details
    ISSN: 1432-0568
    Keywords: Inner ear ; Hair cell ; Stereociliary attachment ; Mouse ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The development of stereociliary attachment to the tectorial membrane was investigated in the mouse cochlea using transmission and scanning electron microscopy. At the 18th gestational day, only the major tectorial membrane can be identified covering the greater epithelial ridge and the inner hair cells in all turns. At the 19th gestational day, the minor tectorial membrane was first seen in the basal turn, over the outer hair cells. During early stages of development, the stereocilia of hair cells were surrounded by a loose fibrillar material underneath the tectorial membrane. After the 10th postnatal day, the outer hair cells' stereocilia were attached to Kimura's (or Hardesty's) membrane, while inner hair cells' stereociliary bundles were attached to the undersurface of the tectorial membrane near the Hensen's stripe. Between the 10th and the 14th postnatal days, the space between the inner hair cells and the first row of outer hair cells widened by virtue of the growth of the heads of pillar cells, and the inner hair cells' stereocilia were displaced towards the Hensen's stripe. After the 14th postnatal day, the inner hair cells' stereociliary bundles detached from the tectorial membrane, while the outer hair cells' stereocilia remained attached to it. The tip-link system, which connects the tips of the stereocilia to the next tallest stereocilia, is present at birth in the outer hair cells. The marginal pillar, that anchored the tectorial membrane to the underlying organ of Corti during development, first appeared on the 6th postnatal day and disappeared on the 14th–15th postnatal day. The present data together with other reports support the idea that although some structures, such as hair cells' stereocilia and innervation, are already formed early during development, the cochlear microarchitecture is not fully developed morphologically and ready to function normally until the end of the second postnatal week in the mouse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185996
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  • 17
    Electronic Resource
    Electronic Resource
    Long-term structural alterations to endothelial cells in vein-to-artery grafts: a quantitative electron microscopic study (1996)
    Springer
    Anatomy and embryology 193 (1996), S. 169-173 
    Details
    ISSN: 1432-0568
    Keywords: Endothelium ; Ultrastructure ; Vein graft ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The intracellular structure of endothelium lining vein-to-artery grafts in rats was analysed, using transmission electron microscopy and morphometry, to determine the ultrastructural adaptations of endothelial cells in this altered vascular environment. Autogenous 4-mm sections of iliolumbar veins were inserted microsurgically into the left common iliac arteries of 16 male Wistar rats. At 3, 6, 26 and 52 weeks the cytoplasmic-vesicular, mitochondrial and rough endoplasmic reticular contents of endothelial cells lining the grafts, the opposite iliac arteries and the remaining ilio-lumbar veins were analysed morphometrically. There was a significant increase in the amount of all these cytoplasmic structures in endothelial cells at 3, 6 and 26 weeks; at 52 weeks there was also a significant increase in the volumes of mitochondria and cytoplasmic vesicles, but not in rough endoplasmic reticulum. It was concluded that the ultrastructure of endothelial cells lining these grafts is changed chronically after graft insertion, and we propose that this may be attributable to altered haemodynamic stresses within the graft.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214707
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  • 18
    Electronic Resource
    Electronic Resource
    Ultrastructure of sympathetic axons and their structural relationship with vascular smooth muscle (1996)
    Springer
    Anatomy and embryology 193 (1996), S. 515-531 
    Details
    ISSN: 1432-0568
    Keywords: Sympathetic axons ; Ultrastructure ; Neuromuscular junctions ; Blood vessels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This review focuses on the more recent findings of the structure of sympathetic postganglionic axons and the association of their varicose terminals with vascular smooth muscle. These studies have investigated the innervation of a wide range of vessels from different regions of the vasculature in the rat, guinea pig and rabbit and have predominantly used serial sections and computerised three-dimensional reconstructions of entire varicosities. They have shown, contrary to previous studies conducted in the 1960s and 1970s, that sympathetic axon varicosities commonly form structurally specialised neuromuscular junctions with vascular smooth muscle cells of most resistance arteries and some small veins. In addition, they have shown that most axon varicosities innervating small arterioles and small mesenteric veins form neuromuscular junctions, indicating that neurotransmitter is primarily released at such neuromuscular junctions. This review discusses the structure of sympathetic neuromuscular junctions, their development, structural diversity and distribution on vessels from different regions of the vasculature. These more recent structural findings and their possible significance for our understanding of mechanisms involved in neural transmission in blood vessels is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00187924
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  • 19
    Electronic Resource
    Electronic Resource
    Coexistence of paired helical filaments and polyglucosan bodies in the same neuron in an autopsy case of Alzheimer’s disease (1996)
    Springer
    Acta neuropathologica 92 (1996), S. 511-514 
    Details
    ISSN: 1432-0533
    Keywords: Key words Paired helical filament ; Polyglucosan ; body ; Alzheimer’s disease ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The coexistence of polyglucosan bodies (PBs) and paired helical filaments (PHFs) in the same neuron is reported in an autopsy case of Alzheimer’s disease. The patient was a 56-year-old Japanese male with a typical clinical course and pathological findings of Alzheimer’s disease. Electron microscopically, numerous neurofibrillary tangles, mainly composed of PHFs, were observed in the neuronal cytoplasm, axons and dendrites. Some of them coexisted with other filamentous structures, which comprised randomly oriented branching filaments with a diameter of 5–10 nm. These structures were compatible with PBs. Glial tangles could not be found. Coexistence of these two structures was thought to occur in neurites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050553
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  • 20
    Electronic Resource
    Electronic Resource
    Eosinophilic bodies in the cerebral cortex of Alzheimer’s disease cases (1996)
    Springer
    Acta neuropathologica 92 (1996), S. 555-561 
    Details
    ISSN: 1432-0533
    Keywords: Key words Homogeneous dense body ; Alzheimer’s disease ; Ultrastructure ; Axonal dystrophy ; Eosinophilic body
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The light microscopical, immunohistochemical and ultrastructural aspects of eosinophilic bodies in the cerebral cortex from patients with Alzheimer’s disease (AD) are described, based on a study of 16 cases of AD, 5 elderly non-demented controls and, as disease controls, 5 cases of Pick’s disease, 9 with progressive supranuclear palsy, 5 with Creutzfeldt-Jakob disease and 1 with Binswanger’s disease. At the light microscopy level, the bodies were clearly separated from the surrounding tissues and were mostly round or elliptic with a diameter of 5–30 μm and a central, intensely eosinophilic core. Ultrastructurally, they consisted of a central homogeneous electron-dense body (HDB), and filamentous structures (resembling either neurofilaments or paired helical filaments) or other small organelles in the periphery. Immunohistochemically, some of these bodies exhibited ring-shaped rims which were positive with antibodies against paired helical filaments, tau-2, phosphorylated neurofilaments and ubiquitin. The bodies were widely distributed throughout the cerebral cortex, but were not observed in the white matter. These bodies were thought to be compatible with one type of axonal dystrophy in the gracile nucleus (termed ‘old’ spheroid by Jellinger), and are here referred to as the HDB-type spheroid based on their ultrastructure. In this study HDB-type spheroids were found in high incidence in the AD cases, but only two HDB-type spheroids were seen in one case of Pick’s disease, and none in any of the other cases of neurodegenerative diseases or in the elderly non-demented controls. It seems plausible that the incidence of HDB-type spheroids in the cerebral cortex might be related to a pathological process and not to a physiological ageing phenomenon, and might be characteristic of, but not unique to, AD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010050561
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  • 21
    Electronic Resource
    Electronic Resource
    Synaptology of the olfactory bulb of an elasmobranch fish, Sphyrna tiburo (1996)
    Springer
    Anatomy and embryology 193 (1996), S. 101-114 
    Details
    ISSN: 1432-0568
    Keywords: Ultrastructure ; Olfaction ; Sharks ; Basal dendrites ; Synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The ultrastructure of the elasmobranch olfactory bulb was examined in order to determine the synaptology of the olfactory circuitry in the bonnethead shark, Sphyrna tiburo. The compartmentalization of the bulb, together with the lack of mitral cell basal dendrites, suggests a different way of performing lateral communication between mitral cells of the olfactory bulb. The results show that granule cells assume an important role by directly interlinking mitral cells. A corollary of this is the segregation of the input onto the mitral cell dendritic arborization: afferent fibers synapse onto the intraglomerular mitral terminals, whereas most local circuit interactions utilize extraglomerular synapses located on the shafts and the somas of the mitral dendrites. Therefore, the elasmobranch synaptic pattern is different from that of higher vertebrates; This might represent the use of a different neural route to achieve the same processing task.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214701
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  • 22
    Electronic Resource
    Electronic Resource
    Quantitative electromicroscope study of the oculomotor parasympathetic neurons projecting to the ciliary ganglion in cats: comparison of the synaptic (axo-somatic and axo-proximal dendritic) organization of anterior-dorsal and ventral cell groups (1996)
    Springer
    Anatomy and embryology 193 (1996), S. 229-238 
    Details
    ISSN: 1432-0568
    Keywords: Preganglionic neuron ; Oculomotor nerve ; Parasympathetic nervous system ; Synapse ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The synaptic organization of the oculomotor parasympathetic preganglionic neurons (OPNs), labeled retrogradely after a horseradish peroxidase (HRP) injection into the ciliary ganglion, was studied in cats by electron microscopy. We divided the OPNs into two groups, anterior-dorsal (ADG) and ventral (VG) cell groups, based upon physiological studies in cats suggesting that accomodation-related OPNs are predominantly located anterior and dorsal to the somatic nuclei of the oculomotor nuclear complex (i.e., the anteromedian and Edinger Westphal nuclei, and the ventral central gray area), while pupillo-constriction-related OPNs are predominantly located ventral to the somatic nuclei (i.e., the ventral tegmental area). The synaptic organization of these two groups was quantitatively compared, using a nested analysis of variance to determine statistical significance (P〈0.05). Partial reconstructions of the labeled somata and proximal dendrites were made from tracings of electron micrographs of every 2nd section in serial ultrathin sections that included the nucleolus or were adjacent to sections that included the nucleolus. The mean number of boutons of apposition on a reconstructed labeled soma of VG was significantly greater than that of ADG (mean ±SD; ADG, 5.3±3.3; VG, 8.6±3.2). The mean synaptic density on a VG soma was significantly greater than on an ADG soma (mean±SD; ADG, 3.74±2.11 counts/100 (μm2; VG, 6.30±1.99 counts/100 μm2). The mean synaptic covering ratio on a VG soma was significantly greater than on an ADG soma (mean±SD; ADG, 5.21±2.91%; VG, 10.14±3.76%). The mean estimated number of boutons of apposition on a VG soma was significantly greater than on an ADG soma (mean±SD: ADG, 53±36; VG, 100±48). Boutons were classified on the basis of the shape of their synaptic vesicles as S-type (containing spherical clear synaptic vesicles) or P-type (containing both flattened and spherical clear synaptic vesicles). The mean S-type/S+P-type bouton ratio on a VG soma was significantly greater than on an ADG soma (mean±SD; ADG, 0.31±0.20; VG, 0.67±0.18). The differences demonstrated in this study reinforce, morphologically, the assumption of functional localization of OPNs, and further allow us to estimate the relative characteristics of the synaptic organization of accommodation-related OPNs and pupillo-constriction-related OPNs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198326
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  • 23
    Electronic Resource
    Electronic Resource
    Early organization of the pituitary gland in Sparus aurata L. (Teleostei) An ultrastructural study (1996)
    Springer
    Anatomy and embryology 193 (1996), S. 441-452 
    Details
    ISSN: 1432-0568
    Keywords: Pituitary gland ; Development ; Ultrastructure ; Sparus aurata (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The cell organization of the pituitary gland and the relationship between neurohypophysis and adenohypophysis in the early developmental stages of the gilthead sea bream, Sparus aurata, were studied by electron microscopy. In newly hatched larvae, the pituitary gland was embedded in the ventral floor of the diencephalon and separated from the hypothalamus by a continuous basal lamina. Elongated mesenchymal cells next to the ventral surface were observed. At this stage, there was no neurohypophysis and the adenohypophysis consisted of undifferentiated endocrine cells with small scarce secretory granules and a few stellate cells, with no distinctive zonation. An incipient neurohypophysis was present in 1-day-old larvae. The first evagination of the neurohypophysis into the adenohypophysis were observed in 2-day-old larvae and developed progressively with age, being deeper in the caudal zone. Two regions in the adenohypophysis, one anterior — the presumptive pars distalis — and one posterior — the presumptive pars intermedia — were found in 2-day-old larvae. Three regions (rostral and proximal pars distalis and pars intermedia) were clearly distinguishable in 4-day-old larvae. The ultrastructural features of the pituitary endocrine cells varied during gland differentiation, with the secretory granules gradually increasing in number and size, accompanying organelle development. Nevertheless, even in the oldest larvae studied (65 days), undifferentiated cells similar to those in the earliest stages were observed. The first blood vessels appeared in the neurohypophysis around 16 days after hatching. During early development, the pituitary gland progressively emerged from the ventral floor of the brain. By 16 days, the principal pattern of the pituitary gland architecture appeared to be established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00185875
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  • 24
    Electronic Resource
    Electronic Resource
    Effects of long-term open-air exposure to fluoride, nitrogen compounds and SO2 on visible symptoms, pollutant accumulation and ultrastructure of Scots pine and Norway spruce seedlings (1996)
    Springer
    Trees 10 (1996), S. 157-171 
    Details
    ISSN: 0931-1890
    Keywords: Key words Conifer ; Fluoride ; Nitrogen ; Sulphur dioxide ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Effects of SO2, aqueous fluoride (NaF) and a solution of nitrogen compounds (NH4NO3) on the visible symptoms, pollutant accumulation and ultrastructure of Scots pine (Pinus sylvestris L.) and Norway spruce [Picea abies (L.) Karst.] seedlings were studied in an open-air experiment lasting for 3 consecutive years. Visible injury symptoms were most pronounced in combination exposures and whenever F was applied. Visible symptoms correlated well with needle pollutant concentrations. Exposure to NaF increased needle F contents particularly when F was applied with SO2 or NH4NO3. This suggests that a reduction in N or SO2 emissions, in F polluted areas, could improve the condition of conifers via decreased accumulation of phytotoxic F in the needles. Norway spruce needles accumulated 2 – 10 times as much S and F as those of Scots pine. Microscopic observations showed various changes in the needle mesophyll cell ultrastructure. In both species, exposure to SO2 increased significantly the amount of cytoplasmic vacuoles, suggesting detoxification of excess sulphate or low pH. F treatments resulted in a significant enlargement of plastoglobuli in Scots pine and a darkening of plastoglobuli in Norway spruce. All exposures enhanced the accumulation of lipid bodies. An increased portion of translucent plastoglobuli was most pronounced in N treatments. Many of the ultrastructural changes and visible symptoms appeared only as number of years exposed increased, indicating that long-term experiments are needed. Both visible symptoms and ultrastructural changes pointed to the more pronounced sensitivity of Norway spruce compared to Scots pine. Ultrastructural results mostly supported earlier qualitative observations of F, N and SO2 effects on needle mesophyll cell ultrastructure. However, no reduction of thylakoids in SO2 containing exposure or curling of thylakoids in F exposure could be detected in the present study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00009644
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  • 25
    Electronic Resource
    Electronic Resource
    Morphology of the keratin filament network in palm and sole skin: evidence for site-dependent features based on stereological analysis (1996)
    Springer
    Archives of dermatological research 288 (1996), S. 55-62 
    Details
    ISSN: 1432-069X
    Keywords: Key words Palmar and plantar skin ; Ultrastructure ; Stereology ; Intermediate filaments ; Keratin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Ridged or glabrous skin of palms and soles has a specialized function and can be preferentially involved in various disorders of keratinization. To better define the morphological features of ridged skin, we carried out a qualitative and quantitative (stereological) analysis of normal epidermis from the palm and sole of four subjects. Skin from the upper arm was examined for control purposes. The study focused on the appearance and arrangement of the keratin filament network in relation to epidermal differentiation. Whereas palm and sole epidermis was essentially similar both qualitatively and quantitatively, it differed markedly from the epidermis from the arm. The volume density of keratin filaments was significantly higher ( P 〈 0.03) in all subcorneal layers of the palm and sole compared with the arm. The volume density of the keratin filaments increased markedly from the basal to the upper spinous layer of ridged skin and they formed denser aggregates in the upper spinous and granular layers, providing an extensive matrix for the deposition of keratohyalin. The presence of dense keratin aggregates appeared to be a distinct ultrastructural feature of human ridged skin. Such keratin aggregates have not been described in normal skin from other sites, but showed some resemblance to the keratin clumps seen in non-ridged skin of patients with the Dowling-Meara form of epidermolysis bullosa simplex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004030050023
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  • 26
    Electronic Resource
    Electronic Resource
    Electron-microscopic study of dopaminergic structures in the medial subdivision of the monkey nucleus accumbens (1996)
    Springer
    Experimental brain research 111 (1996), S. 41-50 
    Details
    ISSN: 1432-1106
    Keywords: Immunocytochemistry ; Dopamine ; Nucleus accumbens ; Ultrastructure ; Monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The medial subdivision of the monkey nucleus accumbens (NAC) is rich in dopamine (DA) and peptides. In the present investigation the mode of DA transmission in the medial subdivision was studied morphologically by light- and electron-microscopic immunocytochemistry using a monoclonal antibody raised against dopamine. The medial subdivision showed extremely dense accumulation of thick DA-immunoreactive varicose fibers. Electron-microscopic observation of single sections revealed that DA afferents had a relatively high incidence (33.2%) of asymmetric junctions in this area. Approximately 50% of the targets were dendritic shafts, 44.2% dendritic spines, and 5.1% somata. Some DA axons showed terminal profiles en passant within the synaptic complex, some of which showed synaptic triads. The unique ultrastructural features of DA terminals in the medial NAC indicate the existence of specific styles of DA transmission in the limbic structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229554
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  • 27
    Electronic Resource
    Electronic Resource
    Reevaluation of synaptic relationships of cerebellar terminals in the ventral lateral nucleus of the rhesus monkey thalamus based on serial section analysis and three-dimensional reconstruction (1996)
    Springer
    Experimental brain research 109 (1996), S. 219-239 
    Details
    ISSN: 1432-1106
    Keywords: Cerebellothalamic projection ; Neuronal circuits ; Ultrastructure ; Synapse ; Monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Terminals of cerebellar afferents (CB) to different regions of the ventral lateral nucleus (VL) of the rhesus monkey thalamus were labeled with wheat germ agglutinin-horseradish peroxidase following injections into the dentate nucleus. Synaptic relationships of 17 CB with projection neuron dendrites (PNd) and local circuit neuron dendrites (LCNd) were analyzed in serial ultrathin sections from dorsal and ventral VL regions, which are known to differ cytoarchitecturally and functionally. Three terminals were reconstructed using three-dimensional (3D) computer image analysis techniques to obtain volumetric and planar measurements. CB in the ventral VL were often flat and elongated with synaptic vesicles arranged in clusters. Each CB was engaged with one PNd and one to four LCNd. A single bouton formed 8–50 synaptic contacts, with those on PNd outnumbering the ones on LCNd 4.1∶1. Only some CB in the ventral VL were engaged in complex synaptic arrangements such as triads and serial synapses. Most CB in the dorsal VL displayed a roundish shape and numerous uniformly distributed synaptic vesicles. They formed 5–25 synaptic contacts with a 3∶1 ratio of contacts on PNd compared with those on LCNd. CB in the dorsal VL participated in a variety of complex synaptic arrangements. Two types of triads were found: classic with CB, PNd and LCNd, and unconventional with CB and two LCNd. CB were also involved in serial synapses with two LCNd or LCNd and another PNd, and serial sequential synapses with two LCNd and a PNd. Three glomerulus-like structures were encountered in the dorsal VL. 3D reconstruction and volumetric measurements revealed that synaptic contacts formed by CB on PNd had varying shapes and sizes (0.022–0.274 μm2). Synapses formed on LCNd were larger (0.09–0.407 μm2). The total area of all active zones of a single CB on LCNd was either equal to or about 40% smaller than that of synapses on PNd. The entire active zone area comprised 1–1.6% of the total CB surface area and did not seem to correlate with the volume. Synaptic contacts formed by associated LCNd on PNd in complex arrangements were usually small (0.021–0.044 μm2). The results suggest that: synapses formed by CB on PNd and LCNd, and synapses formed by LCNd on PNd may differ in strength; a variety of different circuits participate in the processing of cerebellar afferent information in the primate VL; and these circuits differ in functionally different VL subdivisions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00231783
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  • 28
    Electronic Resource
    Electronic Resource
    Synaptic organization of damaged infraorbital nerve axons in perinatal rats: demonstration by galanin immunocytochemistry (1996)
    Springer
    Experimental brain research 110 (1996), S. 47-54 
    Details
    ISSN: 1432-1106
    Keywords: Trigeminal nerve ; Primary afferents ; Synapses ; Ultrastructure ; Vibrissae ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Neonatal transection of the infraorbital nerve (ION; the trigeminal, V, branch that supplies the mystacial vibrissae follicles) results in an upregulation of galanin in the central arbors of primary afferent axons. The present study was undertaken to evaluate the synaptic organization of these galanin-positive primary afferents and compare it with that of normal neurobiotin/biocytin-labeled primary afferent axons from animals of the same age. Examination of 1200 neurobiotin/biocytin-labeled profiles in V nucleus principalis (PrV) of rats killed on postnatal day (P-) 7 indicated that 23.3% (n=279) of these profiles made synaptic contacts: 87.4% were axodendritic, 8.9% were axoaxonic, 2.8% were axosomatic, and 0.7% were axospinous. Evaluation of 1200 galanin-positive profiles in PrV from rats that sustained transection of the ION on P-0 and were killed on P-7 indicated that only 64 (5.3%) of these profiles made synaptic contacts (P〈0.05 compared with the intact animals). Of the galanin-positive profiles that did make synapses in PrV, 81.2% (n=52) were axodendritic and 18.8% (n=12) were axoaxonic. These results indicate that galanin released by damaged ION primary afferents in PrV is likely to affect the activity of second-order V neurons by a paracrine action rather than by acting at specific synapses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241373
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  • 29
    Electronic Resource
    Electronic Resource
    Prediction of prognosis by electron microscopic analysis of myeloma cells (1996)
    Springer
    Annals of hematology 73 (1996), S. 169-173 
    Details
    ISSN: 1432-0584
    Keywords: Key words Multiple myeloma ; Ultrastructure ; Prognosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Myeloma cells were ultrastructurally analyzed in relation to survival in 54 patients with myeloma who were treated with melphalan-prednisolone or cyclophosphamide-prednisolone. Since previous studies by electron microscope had demonstrated that the degree of nuclear-cytoplasmic asynchrony of myeloma cells was associated with poor prognosis, this study focused on three kinds of nuclear abnormalities and eight kinds of cytoplasmic abnormalities. The patients were classified into three groups according to the presence of these abnormalities. The median survival times of the first group with five or fewer of 11 different kinds of abnormalities, the second group with 6–8 abnormalities, and the third group with nine or more abnormalities were 2353, 531, and 115 days, respectively. Furthermore, this classification by ultrastructural abnormalities corresponded to those by the initial hemoglobin concentrations, platelet counts, and percentages of myeloma cells and plasmablasts in the bone marrow. These findings suggest that ultrastructural analysis of nuclear and cytoplasmic abnormalities, in addition to nuclear maturity, of myeloma cells may provide important information for predicting the prognosis in myeloma patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002770050222
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  • 30
    Electronic Resource
    Electronic Resource
    The storage lesion of platelets: ultrastructural and functional aspects (1996)
    Springer
    Annals of hematology 73 (1996), S. 103-112 
    Details
    ISSN: 1432-0584
    Keywords: Key words Platelet concentrates ; Storage ; Ultrastructure ; α-granules ; Open canalicular system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  When prepared and stored as concentrates, platelets undergo a lot of structural, biochemical and functional alterations that lead to an impaired function after transfusion. Besides signs of activation like disc-to-sphere transformation, extension of pseudopodes and loss of storage granules, platelets may display a swollen open canalicular system and changes in the structure of their α-granules. These partly reversible morphological alterations correspond to a deterioration of basic metabolic parameters and a decrease in the reactivity of stored platelets to weak agonists. All these changes occur to a very different degree depending on the methods of preparation and storage. With the introduction of acetate-containing additive solutions, the storage conditions could be greatly improved, and platelets from pooled buffy coats and stored in an acetate-containing medium with at least 20% autologous plasma show the best structural integrity over 8 days of storage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002770050210
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  • 31
    Electronic Resource
    Electronic Resource
    Development and cellular organization ofPinus sylvesfris pollen tubes (1996)
    Springer
    Sexual plant reproduction 9 (1996), S. 93-101 
    Details
    ISSN: 1432-2145
    Keywords: Cytoskeleton ; Microscopy ; Pinus sylvestris ; Pollen ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The organization ofPinus sylvestris pollen tubes during growth was studied by video microscopy of living cells and by electron microscopy after freeze-fixation and freeze-substitution (FF-FS). Pollen germinated and the tubes grew slowly for a total period of about 7 days. Some of the grains formed two tubes, while 10–50% of the tubes ramified. These features are in accordance with development in vivo. The cytoplasmic hyaline cap at the tip disappeared during the 2nd or 3rd day of culture. Aggregates of starch grains progressively migrated from the grain into the tube and later into the branches. Vacuoles first appeared at day 2 and eventually filled large parts of the tube. The tube nucleus was located at variable distances from the tip. Some of the organelles showed linear movements in a mostly circulatory pattern, but the majority of the organelles showed brownian-like movements. Rhodamine-phalloidin-stained actin filaments had a gross axial orientation and were found throughout the tube including at the tip. The ultrastructure of pollen tubes was well preserved after FF-FS, but signs of shrinkage were visible. The secretory vesicles in growing tips were not organized in a vesicle cone, and coated pits had a low density with only local accumulations, which is in accordance with slow growth. The mitochondria contained small cristae and a darkly stained matrix and were located more towards the periphery of the tube, indicating low respiratory activity and low oxygen levels. The dictyosomes carried typical trans-Golgi networks, but some contained less than the normal number of cisternae. Other elements of the cytoplasm were irregularly spaced rough endoplasmic reticulum, many multivesicular bodies, lipid droplets and two types of vacuoles. The typical organization associated with tip growth in angiosperm pollen tubes, e.g.Nicotiana tabacum, was not present inP. sylvestris pollen tubes. The different morphology may relate to the growth rate and not to the type of growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02153056
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  • 32
    Electronic Resource
    Electronic Resource
    Development and cellular organization of Pinus sylvestris pollen tubes (1996)
    Springer
    Sexual plant reproduction 9 (1996), S. 93-101 
    Details
    ISSN: 1432-2145
    Keywords: Key words Cytoskeleton ; Microscopy ; Pinus sylvestris ; Pollen ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The organization of Pinus sylvestris pollen tubes during growth was studied by video microscopy of living cells and by electron microscopy after freeze-fixation and freeze-substitution (FF-FS). Pollen germinated and the tubes grew slowly for a total period of about 7 days. Some of the grains formed two tubes, while 10–50% of the tubes ramified. These features are in accordance with development in vivo. The cytoplasmic hyaline cap at the tip disappeared during the 2nd or 3rd day of culture. Aggregates of starch grains progressively migrated from the grain into the tube and later into the branches. Vacuoles first appeared at day 2 and eventually filled large parts of the tube. The tube nucleus was located at variable distances from the tip. Some of the organelles showed linear movements in a mostly circulatory pattern, but the majority of the organelles showed brownian-like movements. Rhodamine-phalloidin-stained actin filaments had a gross axial orientation and were found throughout the tube including at the tip. The ultrastructure of pollen tubes was well preserved after FF-FS, but signs of shrinkage were visible. The secretory vesicles in growing tips were not organized in a vesicle cone, and coated pits had a low density with only local accumulations, which is in accordance with slow growth. The mitochondria contained small cristae and a darkly stained matrix and were located more towards the periphery of the tube, indicating low respiratory activity and low oxygen levels. The dictyosomes carried typical trans-Golgi networks, but some contained less than the normal number of cisternae. Other elements of the cytoplasm were irregularly spaced rough endoplasmic reticulum, many multivesicular bodies, lipid droplets and two types of vacuoles. The typical organization associated with tip growth in angiosperm pollen tubes, e.g. Nicotiana tabacum, was not present in P. sylvestris pollen tubes. The different morphology may relate to the growth rate and not to the type of growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050015
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  • 33
    Electronic Resource
    Electronic Resource
    Quantitative analysis of ultrastructural changes during zygotic and somatic embryogenesis in pearl millet (Pennisetum glaucum [L.] R. Br.) (1996)
    Springer
    Sexual plant reproduction 9 (1996), S. 286-298 
    Details
    ISSN: 1432-2145
    Keywords: Somatic embryogenesis ; Ultrastructure ; Pennisetum ; Poaceae ; Morphometrics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ultrastructural changes during zygotic and somatic embryogenesis in pearl millet (Pennisetum glaucum [L.] R. Br.) were quantified using morphometric techniques. The total area per cell profile and the cell volume percentage of the whole cell, endoplasmic reticulum (ER), Golgi bodies, mitochondria, nuclei, lipids, plastids, starch grains and vacuoles were measured and comparisons made between three zygotic and three somatic embryo developmental stages. All measurements were taken from scutellar or scutellar-derived cells. Zygotic embryogenesis was characterized by increases in cell size, lipids, plastids, starch, Golgi bodies, mitochondria and ER. Somatic embryogenesis was characterized by two phases of cell development: (1) the dedifferentiation of scutellar cells involving a reduction in cell and vacuole size and an increase in cell activity during somatic proembryoid formation and (2) the development of somatic embryos in which most cell organelle quantities returned to values found in late coleoptile or mature predesiccation zygotic stages. In summary, although their developmental pathways differed, the scutella of somatic embryos displayed cellular variations which were within the ranges observed for later stages of zygotic embryogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02152704
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    Electronic Resource
    Morphological variability of smooth muscle cells in human nasal swell bodies (1996)
    Springer
    European archives of oto-rhino-laryngology and head & neck 253 (1996), S. 147-151 
    Details
    ISSN: 1434-4726
    Keywords: Nasal swell bodies ; Morphology ; Smooth muscle cell ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The complex functional behavior of nasal swell bodies is still not completely understood. In the present study the histology of the vessels involved in the swelling mechanism is examined and the ultrastructural appearances described of the different types of smooth muscle cells located in the vascular wall of swell bodies in the human inferior turbinate. Even though the majority of smooth muscle cells of the nasal swell bodies showed a normal, elongated appearance comparable to other smooth muscle cells elsewhere in the body, a variety of cells with atypical shapes could be detected that have not been described previously in vessels of the nasal mucosa. The diameters of the smooth muscle cells in general were strikingly variable. The individual smooth muscle cells were surrounded by a basal lamina that was occasionally disrupted or doubled. Myoblasts were separated by a connective tissue space containing collagen fibrils, mature elastin fibers and bundles of microfibrils. The latter two types of fibers and fibrils occurred mainly in the outer parts of the muscular coat. The endowment of cytoplasmic components was similar in all smooth muscle cells of the vascular wall in the swell bodies. These findings indicate that the specific feature of smooth musculature presumably resides in the unusual morphological variability of the single cells present, as well as in the striking heterogeneity of the arrangement of bundles of these cells in the vascular wall.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00615112
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  • 35
    Electronic Resource
    Electronic Resource
    Immunocytochemical localization of Tamm-Horsfall protein in the kidneys of normal and nephrolithic rats (1996)
    Springer
    Urological research 24 (1996), S. 201-209 
    Details
    ISSN: 1434-0879
    Keywords: Calcium oxalate ; Hyperoxaluria ; Nephrolithiasis ; Tamm-Horsfall protein ; Immunocytochemistry ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Studies using in vitro systems have indicated that Tamm-Horsfall protein (THP) can interact with calcium oxalate (CaOx) crystals during kidney stone formation. However, information regarding the nature of its participation in this process remains controversial and unclear. In order to better understand the putative interaction of THP and crystals in vivo, we compared the localization of THP in normal rats and in chronic and semi-acute rat models of nephrolithiasis. In these rats, CaOx crystal deposits were induced in the kidneys by administering ethylene glycol (EG) in drinking water. The formation of CaOx mono- and dihydrate aggregates in the urine was confirmed by scanning electron microscopy. Immunohistochemical localization, as well as protein A-gold labeling at the ultrastructural level, demonstrated that in addition to its normal distribution, THP specifically associated with the renal crystal deposits. The THP-containing, organic matrix-like material consisted of a fine, fibrillar meshwork surrounding individual crystals and their aggregates. In addition, THP also appeared in the papilla, where it is normally absent, concurrent with the appearance of crystal deposits in the kidneys. These observations indicate that in nephrolithic rats the normal localization of THP is altered. Such an alteration may indicate an important physiological event related to crystal aggregation and kidney stone formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295893
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  • 36
    Electronic Resource
    Electronic Resource
    Morphological changes in the central vacuole ofBlastocystis hominis during in vitro culture (1996)
    Springer
    Protoplasma 194 (1996), S. 63-68 
    Details
    ISSN: 1615-6102
    Keywords: Blastocystis hominis ; Central vacuole ; In vitro culture ; Accumulation ; Carbohydrates ; Lipids ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Morphological changes in the central vacuole during the growth in in vitro culture ofBlastocystis hominis were investigated by light and electron microscopy. Most cells in log phase and an early stationary phase showed a positive staining reaction in the central vacuole with PAS or Sudan black B stain, whereas cells in late stationary phase showed few positive reactions. Electron microscopic observations revealed that 95% ofB. hominis cells in log phase and 50% of cells in early stationary phase, had a substantial accumulation of electron-dense material in the central vacuole. In contrast, only 25% of the organisms in late stationary phase had an electron-dense central vacuole, while more than 50% of cells had an electron-lucent central vacuole. These results indicate thatB. hominis accumulated carbohydrates and lipids in the central vacuole during cell growth and that the organism probably consumed these metabolic substances during stationary growth. Therefore, it is strongly suggested that the central vacuole is an important organelle for storage of metabolic substances, such as carbohydrates and lipids, required for cell growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01273168
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    Electronic Resource
    Electronic Resource
    Phagocytosis of lectin-opsonized fungal cells and endocytosis of the ligand by insect Spodoptera exigua granular hemocytes: an ultrastructural and immunocytochemical study (1996)
    Springer
    Cell & tissue research 285 (1996), S. 57-67 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Phagocytosis ; Insect hemocytes ; Lectins ; Fungal entomopathogens ; Ultrastructure ; Immunocytochemistry ; Cytoskeleton ; Spodoptera exigua (Insecta) ; Paecilomyces farinosus (Fungi-Deuteromycotina)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Phagocytosis of blastospores of the fungal entomopathogen Paecilomyces farinosus by granular hemocytes from larvae of Spodoptera exigua (beet armyworm) was studied. Blastospores were opsonized with a galactose-specific lectin purified from S. exigua hemolymph or with peanut agglutinin prior to incubation with hemocytes. Observations of thin sections revealed that pseudopodia extending from granulocytes attached to ligands (lectins, lectin conjugates) on the blastospores, and that the ligands became detached from the fungal surfaces and were endocytosed by granulocytes via coated pits on the plasma membrane. Coated vesicles bearing the endocytosed molecules appeared to be transported to the hemocytic granules. In other cases, ligand still coated the blastospores after phagocytosis and may have later concentrated within the phagosome along with digested fungal cell wall components. Phagocytosis of blastospores and clustering of a biotinylated lectin conjugate on or within the granulocytes were inhibited by drugs targeting cytoskeletal elements. Actin was concentrated in the pseudopodia of phagocytic granulocytes and may be directly associated with lectin receptor(s). Microtubules were abundant in the granulocytes, sometimes in specific regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050620
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  • 38
    Electronic Resource
    Electronic Resource
    The ultrastructure of spiralled collagen in liver fibrosis (1996)
    Springer
    Medical molecular morphology 29 (1996), S. 153-158 
    Details
    ISSN: 1860-1499
    Keywords: Spiralled collagen ; Hepatitis ; Liver fibrosis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An ultrastructural study was performed using oölong tea polyphenols for staining liver tissue from 5 patients with acute hepatitis, 20 patients with chronic hepatitis, and 5 patients with alcoholic liver disease. Spiralled collagen was seen in the region of the portal tract in all of the patients, but not in the periportal region, perisinusoidal region, or sinusoidal wall. The amount of spiralled collagen relative to the total amount of collagen fibrils was greater in patients with hepatitis than in those with alcoholic liver disease. The occurrence of spiralled collagen appears to be a degenerative phenomenon as indicated by observations of its three-dimensional structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02348069
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  • 39
    Electronic Resource
    Electronic Resource
    Structure and development of cell connections in the phloem ofMetasequoia glyptostroboides needles I. Ultrastructural aspects of modified primary plasmodesmata in Strasburger cells (1996)
    Springer
    Protoplasma 193 (1996), S. 191-203 
    Details
    ISSN: 1615-6102
    Keywords: Endoplasmic reticulum ; Metasequoia ; Phloem-loading ; Plasmodesmata ; Strasburger cells ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Symplasmic contacts of Strasburger cells in the mature needle ofMetasequoia glyptostroboides were analysed with special regard to changes of plasmodesmata in fine structure and distribution. In meristematic cells simple primary plasmodesmata are evenly distributed throughout the entire wall, whereas in mature Strasburger cells plasmodesmata are aggregated in defined, dome-shaped wall thickenings. The elongated, often multiple-branched cytoplasmic strands show a distinct neck region besides a considerably dilated sleeve region confluent with cavities, which have formed at branching sites of plasmodesmata in various planes of the wall thickening. Most branches radiating from these cavities connect the protoplasts of the adjacent cells; occasionally some strands are discontinuous. The desmotubules of both, continuous and discontinuous plasmodesmal branches exhibit great variability in structure and number: they may be partially dilated, multiple-stranded and branched within single plasmodesmal branches. Fine structurally, plasmodesmata of Strasburger cells show great resemblance with developing sieve pores of conifers. This characteristic fine structure implicates a special role of the endomembrane system for phloem loading in theMetasequoia leaf.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01276645
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  • 40
    Electronic Resource
    Electronic Resource
    Dynamics of vegetative cytoplasm during generative cell formation and pollen maturation inArabidopsis thaliana (1996)
    Springer
    Protoplasma 194 (1996), S. 81-90 
    Details
    ISSN: 1615-6102
    Keywords: Arabidopsis ; Pollen ; Vegetative cytoplasm ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ultrastructural changes of pollen cytoplasm during generative cell formation and pollen maturation inArabidopsis thaliana were studied. The pollen cytoplasm develops a complicated ultra-structure and changes dramatically during these stages. Lipid droplets increase after generative cell formation and their organization and distribution change with the developmental stage. Starch grains in amyloplasts increase in number and size during generative and sperm cell formation and decrease at pollen maturity. The shape and membrane system of mitochondria change only slightly. Dictyo-somes become very prominent, and numerous associated vesicles are observed during and after sperm cell formation. Endoplasmic reticulum appears extensively as stacks during sperm cell formation. Free and polyribosomes are abundant in the cytoplasm at all developmental stages although they appear denser at certain stages and in some areas. In mature pollen, all organelles are randomly distributed throughout the vegetative cytoplasm and numerous small particles appear. Organization and distribution of storage substances and appearance of these small particles during generative and sperm cell formation and pollen maturation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01273170
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  • 41
    Electronic Resource
    Electronic Resource
    Changes in the structure ofArabidopsis thaliana during female development of the plant-parasitic nematodeHeterodera schachtii (1996)
    Springer
    Protoplasma 194 (1996), S. 103-116 
    Details
    ISSN: 1615-6102
    Keywords: Arabidopsis thaliana ; Cyst nematodes ; Development ; Histology ; Syncytium ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The beet cyst nematodeHeterodera schachtii is able to establish a feeding structure (syncytium) in the vascular tissue of roots and shoots ofArabidopsis thaliana. Histological and ultrastructural studies were performed to assess plant responses during the development of juvenile females under monoxenic conditions. After destructively invading a root the nematode selects and pierces a single procambial cell with its stylet and transforms it into an initial syncytial cell (ISC) by secretory activity. The first most obvious changes in the ISC occur in the vacuolar system and at the wall. Differentiation of a central vacuole is impeded resulting in the formation of numerous small vacuoles. Multivesicular and paramural bodies are formed. An electron translucent material is deposited on the cell wall. Partial dissolution of the cell wall leads to the formation of a syncytium. At the juveniles' last pre-adult developmental stage the syncytium attains its maximum longitudinal and radial extension, occupying a major part of the central cylinder. Its features are indicative of a very high level of metabolic activity. The hypertrophied syncytium is ensheathed by a peridermal cover in which secondary xylem and phloem elements are interspersed. When females die the syncytia degenerate. The ultrastructural and histological features of syncytia described from roots are also found in syncytia induced in aerial parts of the plant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01273172
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  • 42
    Electronic Resource
    Electronic Resource
    Plastid biogenesis in embryonic pea leaf cells during early germination (1996)
    Springer
    Protoplasma 195 (1996), S. 59-67 
    Details
    ISSN: 1615-6102
    Keywords: Endoplasmic reticulum ; Germination ; Lipid bodies ; Pisum sativum ; Plastid biogenesis ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of embryonic pea leaf cells was examined during the first 24 h of imbibition of dry seeds. Special attention was paid to plastids, which underwent two interesting interactions during this period. The first was a close physical association between the endoplasmic reticulum and plastids. The second was an association of numerous lipid bodies with the surface of plastids. The functional implications of these associations are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279186
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  • 43
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    Electronic Resource
    The ultrastructure of hemocytes inDactylopius confusus (Cockerell), and the role of granulocytes in the synthesis of cochineal dye (1996)
    Springer
    Protoplasma 192 (1996), S. 199-216 
    Details
    ISSN: 1615-6102
    Keywords: Scale insect ; Cochineal scale ; Hemocytes ; Coccid ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructural study of free circulating hemocytes in the adult cochineal scale,Dactylopius confusus (Cockerell), demonstrated five cell types: prohemocytes, typical granulocytes (T-granulocytes), oenocytoids, plasmatocytes, and granulocytes with modified sub-cellular structure to perform a special synthetic and secretory function, which we refer to as “modified granulocytes” (M-granulocytes). Prohemocytes showed undifferentiated sub-cellular structure of the basic stem cell type (i.e., high cytoplasmic density with numerous ribosomes, centrally located large nucleus with a distinct nucleolus, and poorly developed endoplasmic reticulum). The commonly observed typical granulocytes (T-granulocytes) had several smooth endoplasmic reticulum (SER) with dilated cisternae and many SER-derived membrane bounded granules of different sizes and electron density. Oenocytoids were identified by the presence of many crystals, RER-originated fine secretory granules, and an eccentric nucleus. Plasmatocytes were easily characterized by their variable shapes and irregular outline with pseudopodia-like cytoplasmic extensions, possession of an elongated lobed nucleus, multivesicular bodies, RER-derived membrane bounded, electron-dense, lysosomelike vacuoles, well-developed SER cisternae, and numerous pinocytic and SER-originated vesicles of different sizes along the peripheral region. M-granulocytes comprised the largest proportion of hemocytes in all samples observed. M-granulocytes were distinguished not only by the presence of membrane bounded granules of different sizes and electron density, but by the possession of large nuclei with distinct nucleoli, many mitochondria, and a highly developed network of rough endoplasmic reticulum (RER). M-granulocytes had abundant, rosette-shaped, RER-derived chains of fine secretory granules, which accumulated in the cytoplasm and vacuoles, and were ultimately deposited into the hemolymph by exocytosis. These fine granules gave a positive result with periodic acid-Schiff (PAS) test. Based on RER-synthesized fine secretory granules (M-granulocytes), their ultimate deposition into hemolymph, the red pigmentation of hemolymph, positive PAS histochemical test of these granules, and the high population of these hemocytes, no such cell type has been described in previous studies in insects. The sub-cellular structure of the granulocyte in this insect has been modified to perform a special synthetic and secretory function (i.e., possibly the synthesis of the red pigment found in hemolymph, which has been the source of commercially important cochineal dye).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01273892
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  • 44
    Electronic Resource
    Electronic Resource
    Endoplasmic reticulum derived decorated tubules in the sieve elements ofNymphaea (1996)
    Springer
    Protoplasma 193 (1996), S. 213-221 
    Details
    ISSN: 1615-6102
    Keywords: Decorated tubules ; Endoplasmic reticulum ; Nymphaea ; Sieve elements ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Bundles of decorated tubules found in the sieve elements ofNymphaea have been studied with the transmission electron microscope. Comparatively straight tubules (100 nm in diameter) arise from the endoplasmic reticulum during early stages of sieveelement development and subsequently associate into bundles of up to 100 tubules that parallel the longitudinal cell axis. From the start of their formation the tubules are structurally distinct from other ER profiles due to their dense decoration with particles. High magnifications reveal an orderly array of the particles (about 24 surround a 100 nm tubule) and suggest a modification of their membrane so that it is no longer dissolvable into a regular three-layered structure. Later during sieve-element ontogeny the decorated tubules get invaginated by smooth ER membranes, thereby squeezing out the intratubular (extracytoplasmic) space. As a result a double mantle is formed that surrounds a plasmatic cylinder. Decorated 100 nm tubules with inner membranes are present in enucleate mature sieve elements ofNymphaea alba andN. tuberosa. Considerably larger tubules (about 200 nm in diameter) were found inN. Candida andN. tetragona and occasionally also inNuphar and Barclaya, two other genera from the same family. The decoration of the tubules and their subsequent invagination by smooth membranes are discussed with respect to the controlled autolysis of sieve elements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01276647
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  • 45
    Electronic Resource
    Electronic Resource
    Mineralization during matrix-vesicle-mediated mantle dentine formation in molars of albino rats: a microanalytical and ultrastructural study (1996)
    Springer
    Cell & tissue research 284 (1996), S. 223-230 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Mineralization ; Matrix vesicles ; Dentine ; Ultrastructure ; Element analysis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The purpose of this study was to elucidate the mineralization process of mantle dentine by ultrastructural and element-analytical investigation of matrix vesicles and successive stages. Upper second molars of albino rats were cryofixed and embedded in resin after freeze drying. Semithin dry sections were prepared for analyzing the calcium and phosphorus concentrations in the mineralized matrix vesicles or noduli, larger mineralized islands, and the mantle dentine. For ultrastructural studies, it was necessary to reduce section contact with hydrous fluids to a minimum in order to avoid preparation artifacts. The first mineral deposits were recognized as dot-like formations both in the interior of matrix vesicles and in association with the inner vesicle membrane. This indicated the existence of mineral nucleating sites located both at the inner membrane and at calcium-phosphate-binding macromolecules in the interior of the matrix vesicles. A significantly higher mineral content was found in mineralized matrix vesicles than in the mineralized extravesicular regions of the mineralized islands, suggesting the existence of a rapidly and densely mineralizing matrix in the matrix vesicles. A significant increase in mineral content per volume proceeding from the mineralized islands to mantle dentine suggested a further increase in the density of mineral.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050582
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  • 46
    Electronic Resource
    Electronic Resource
    Acute monocytic leukaemia (M5a) in a horse (1996)
    Springer
    Comparative clinical pathology 6 (1996), S. 111-114 
    Details
    ISSN: 1433-2981
    Keywords: Alpha naphthyl acetate esterase ; Cytochemistry ; Horse ; Monocyte ; Monocytic leukaemia ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Acute monocytic leukaemia (M5a) was diagnosed in a 17-year-old Standardbred gelding with lethargy, intermittent pyrexia, oedema of the limbs, harsh lung sounds and submandibular lymphadeopathy. Haematological findings included moderately severe anaemia, thrombocytopenia and a leucocyte count within the reference interval, but characterised by neutropenia and numerous blast cells. Monocytic lineage of the cell population was suggested by examination of Wright-Leishman-stained blood and bone marrow smears. A panel of cytochemical stains disclosed diffuse cytoplasmic α-naphthyl-acetate esterase activity which could be markedly inhibited or abolished in all leukaemic cells by pretreatment with sodium fluoride. In ultrastructural preparations of buffy coat, neoplastic monoblasts had one to two nucleoli, dispersed chromatin, elongated mitochondria, scattered profiles of rough endoplasmic reticulum, bundles of microfilaments and pseudopodia. More differentiated monocytoid cells had infrequent lysosomal granules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00426052
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  • 47
    Electronic Resource
    Electronic Resource
    Hochauflösende Rasterelektronenmikroskopie von isolierten äußeren Haarzellen (1996)
    Springer
    HNO 44 (1996), S. 630-633 
    Details
    ISSN: 1433-0458
    Keywords: Schlüsselwörter Innenohr ; Ultrastruktur ; Einzelzelle ; SEM ; Key words Inner ear ; Ultrastructure ; Isolated hair cells ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Isolated hair cell preparations have gained wide acceptance as a model for studying physiological and molecular properties of the sensory cells involved in the hearing process. Ultrastructural details, such as stereocilia links, lateral membrane substructure or synaptic links are of crucial importance for normal sensory transduction. For this reason, we developed a high-resolution scanning electron microscopy (SEM) procedure to study the surface of isolated hair cells. Cells were mechanically and/or enzymatically separated, isolated and immobilized on cover slips by alcian blue and fixed by 2% glutardialdehyde or 1% OsO4. After dehydration, preparations were critical point-dried and sputter-coated with gold-palladium (2–4 nm). Up to 5 nm resolution was achieved. Optimal fixation kept the cells in their typical cylindrical forms. Preservation of the stereocilia and the apical plates of the outer hair cells depended strongly on the fixation process. Tip- and side-links were observed only sporadically because of the aggressive preparation procedure. The lateral plasma membranes of the cell bodies showed regular granular structures of 5–7 nm diameter at maximal magnification. The granular structure of the cell membrane seemed to correspond to putataive transmembrane proteins believed to generate membrane-based motility. The remnants of the nerve endings and/or supporting cells usually covered the cell base. The preservation of the cells was better when enzymatic isolation was omitted. The technique used allowed for high resolution ultrastructural examination of isolated hair cells and, when combined with immunological labeling, may permit the identification of proteins at a molecular level.
    Notes: Zusammenfassung Isolierte Sensorzellen aus dem Innenohr stellen ein akzeptiertes Modell zur Untersuchung von elektrophysiologischen und molekularen Eigenschaften dieser Zellen dar. Um morphologische Substrukturen zu erfassen, haben wir ein rasterelektronenmikroskopisches (REM) Untersuchungsprotokol zur Darstellung der Oberfläche isolierter Haarzellen entwickelt. Die Zellen wurden mechanisch und/oder enzymatisch isoliert und auf mit Alcianblau (0,1–1%) beschichteten Glasplättchen immobilisiert. Es folgte eine chemische Fixation mit Glutardialdehyd und Osmiumtetroxyd. Nach einer Ethanoldehydratation und Trocknung nach der Kritischen-Punkt-Methode mit Hilfe von CO 2 wurden die Proben mit einer dünnen Schicht Gold-Paladium (2–4 nm) beschichtet. Die Untersuchung erfolgte am REM der Fa. Hitachi S-800. Bei optimaler Fixierung wurde die typische zylindrische Form der Zellen erhalten. Wegen der aggressiven Preparation gelang die Darstellung von Tip- und Side-links nur unregelmäßig. Die laterale Zellwand erschien bei maximaler Vergrößerung regelmäßig granuliert bei einer Korngröße von 5–7 nm. Bei der dargestellten Granulation handelt es sich um intramembranöse Partikel (IMP). Diese können Proteinen entsprechen, die durch ihre Fähigkeit zur spannungsabhängigen Konformationsänderung die Motilität der Haarzellen erklären lassen. An der basalen Region der Zelle war keine Granulation feststellbar. Dieser Bereich war mit Nervenendigungen bzw. Resten der Deiters-Zellen bedeckt. Diese Technik ermöglicht die REM-Untersuchung von isolierten Sensorzellen aus dem Innenohr.
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    URL: http://dx.doi.org/10.1007/s001060050068
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  • 48
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    Electronic Resource
    Cytochemical staining and ultrastructural characteristics of peripheral blood leucocytes from the yellow rat snake (Elaphe obsoleta quadrivitatta) (1996)
    Springer
    Comparative clinical pathology 6 (1996), S. 86-91 
    Details
    ISSN: 1433-2981
    Keywords: Cytochemical staining ; Leucocytes ; Snake ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cytochemical staining and ultrastructural characteristics of peripheral blood leucocytes from the yellow rat snake are described. A panel of cytochemical stains, including demonstration of myeloperoxidase, acid phosphatase, naphthol AS-D chloracetate esterase, alpha-naphthol butyrate esterase and alkaline phosphatase activities; and periodic acid-Schiff and Sudan Black-B staining was performed. Snake heterophils lacked peroxidase, alkaline phosphatase and acid phosphatase activity. Azurophils stained positively for all stains except alkaline phosphatase activity. Lymphocytes showed positive acid phosphatase activity. Differentiation of thrombocytes from lymphocytes was very difficult even with cytochemical staining. Only a minor staining difference was observed with periodic acid-Schiff stain. Thrombocytes exhibited coarse, dark, purple stippling usually located in the polar area of the cytoplasm, whereas lymphocyte staining varied from none to very fine, pale pink granules dispersed throughout the cytoplasm. Ultrastructural characteristics were similar to those of mammalian leucocytes with the exception that the snake basophil granules have no crystalline matrix, and heterophil granules appeared as large, elongate, membrane bound structures of varying density with no distinct core or matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00426047
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  • 49
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    Electronic Resource
    Intermittent compressive load stimulates osteogenesis and improves osteocyte viability in bones cultured “in vitro” (1996)
    Springer
    Clinical rheumatology 15 (1996), S. 563-572 
    Details
    ISSN: 1434-9949
    Keywords: Organ Culture ; Intermittent Compressive Force ; Osteogenesis ; Ultrastructure ; Osteocyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of mechanical stresses on osteogenesis, the viability of osteocytes and their metabolic activity in organ culture of bones intermittently loaded “in vitro” are reported. Metatarsal bones, isolated from 12-day-old rats, were cultured in BGJb medium (with 10% foetal calf serum, 75µg/ml of ascorbic acid, 100 U/ml of penicillin and 100µg/ml of streptomycin), in humidified air enriched by 5% CO2 and 30% O2, and loaded in our original device for 1/2 an hour at 1 Hz. homotypic isolated and unloaded bones, cultured in the same medium, were taken as controls. The ALP (alkaline phophatase activity) increases in the media of loaded bones in comparison with the control bones. The percentage of viable osteocytes is significantly greater in loaded than in control bones. TEM observations demonstrate that in both loaded and control unloaded bones, osteocytes show well developed organelle machinery and several gap junctions with adjacent cellular processes. In the cells of loaded bones, however, a higher number of cytoplasmic organelles and gap junctions were found. In particular, RER increases twice, gap junctions three times. The induced osteogenesis and the TEM observations demonstrate the suitability of this experimental model and support the recent advanced hypothesis according to which the mechanical loading may exert a trophic function on osteocytes, stimulating both the proteic synthesis in the above-mentioned cells and the cell-to-cell communication. Furthermore, the loading is likely to exert a biological stimulus on osteoblasts via signalling molecules produced by osteocytes.
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    URL: http://dx.doi.org/10.1007/BF02238545
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    Effect of α-fluoromethylhistidine-evoked histamine depletion on ultrastructure of endocrine cells in acid-producing mucosa of stomach in mouse, rat and hamster (1996)
    Springer
    Cell & tissue research 286 (1996), S. 375-384 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Endocrine cells ; Stomach-ECL cells ; Ultrastructure ; Histamine ; α-Fluoromethylhistidine ; Secretory vesicles ; Rat (Sprague Dawley) ; Mouse (NMRI) ; Hamster (Syrian)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The oxyntic mucosa of the mammalian stomach is rich in endocrine cells, such as ECL cells, A-like cells, somatostatin cells, D1/P cells and, in some species, enterochromaffin cells. The various endocrine cell types can be distinguished on the basis of their characteristic cytoplasmic granules and vesicles. The ECL cells contain numerous large secretory vesicles and relatively few, small electron-dense granules and small clear microvesicles. We have suggested that in the rat the ECL cells contain most of the gastric histamine with the secretory vesicles as the major histamine storage site in these cells. α-Fluoromethylhistidine is an irreversible inhibitor of histidine decarboxylase, the histamine-forming enzyme. We have previously shown that this enzyme inhibitor depletes histamine from the ECL cells in the rat and reduces the number of secretory vesicles in the cytoplasm. In the present study, we have examined whether α-fluoromethylhistidine affects the ECL cells in other species and whether it affects other types of endocrine cells in the oxyntic mucosa of the rat. Mice, rats and hamsters were treated with the inhibitor (3 mg/kg per h) via minipumps subcutaneously for 24 h. This treatment lowered the oxyntic mucosal histamine concentration by 65–90% and the number and volume density of the secretory vesicles by 85–95% in the ECL cells of the three species examined. In contrast, the number and volume density of granules and microvesicles were not greatly affected. No evidence was found for an effect of α-fluoromethylhistidine on A-like cells, somatostatin cells or D1/P cells of the rat stomach, suggesting that, unlike the ECL cells, they do not contain histamine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050707
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    On the exact solution of the Schrödinger equation with a quartic anharmonicity (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 63-71 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new version of solutions in the form of an exponentially weighted power series is constructed for the two-dimensional circularly symmetric quartic oscillators, which reflects successfully the desired properties of the exact wave function. The regular series part is shown to be the solution of a transformed equation. The transformed equation is applicable to the one-dimensional problem as well. Moreover, the exact closed-form eigenfunctions of the harmonic oscillator can be reproduced as a special case of the present wave function. © 1996 John Wiley & Sons, Inc.
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    Announcement (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 139-139 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560570104
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    The extended Koopmans' theorem Fock operator and the generalized overlap amplitude one-electron operator (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 391-399 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The wave function of a system may be expanded in terms of eigenfunctions of the N -1 electron Hamiltonian times one-particle functions known as generalized overlap amplitudes (GOAS). The one-electron operator whose eigenfunctions are the GOAS is presented, without using an energy-dependent term as in the one-particle Green function or propagator approach. It is shown that this operator and the extended Koopmans' theorem (EKT) one-electron operator are of similar form, but perform complementary roles. The GOA operator begins with one-electron densities and total energies of N -1 electron states to generate the two-matrix and total energy of an N-electron state. The EKT operator begins with the two-matrix of an N-electron state to generate one-electron densities and ionization potentials (or approximations thereto) for N -1 electron states. However, whereas the EKT orbitals must be linearly independent, no such restriction applies to the GOAS. © 1996 John Wiley & Sons, Inc.
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    DNA base amino groups and their role in molecular interactions: Ab initio and preliminary density functional theory calculations (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 959-970 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Interactions of DNA bases frequently involve the DNA base amino groups. In contrast to the empirical force fields, the ab initio calculations predict nonplanar DNA base amino groups. The same conclusion also follows from the density functional theory (DFT) calculations. Both local and nonlocal density approximations were used. Optimized geometries of two other molecules with nonplanar amino groups (aniline, formamidine) are presented for comparison. The influence of nonplanar DNA base amino groups on the conformational variability of DNA is discussed. © 1996 John Wiley & Sons, Inc.
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    Theoretical studies on the decarboxylation reaction in thiamin catalysis (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 943-948 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational behavior and the stability of thiazolium and thiamin diphosphate (ThDP) adducts formed by the C2 addition of the substrates pyruvate and glyoxylate to the corresponding thiamin systems are investigated within the force-field version PIMM90 as well as the semiempirical AM1 and PM3 methods. Moreover, the reaction coordinate of the decarboxylation process of the adducts with respect to the C2α(SINGLEBOND)COO- bond are calculated by PM3 and AM1. The calculations on the key intermediates of the Breslow mechanism are performed in order to study the steric aspects of both substrate adducts that show a different pathway in the catalytic cycle. The alternative structural findings for the decarboxylation products are compared with first 6-31C* studies on the corresponding thiazolium model systems. Especially, the PM3 calculations show that the elimination of CO2 is favored if the arrangement of the carboxylate group is nearly perpendicular to the plane of the thiazolium ring. These results support the least-motion maximum-overlap mechanism in the enzymatic decarboxylation reaction, proposed by Kluger. The most stable conformers of the ThDP adducts and its decarboxylation products are characterized by V-like structures and the formation of a significant intramolecular hydrogen bonding under participation of the 4′-aminopyrimidine ring. © 1996 John Wiley & Sons, Inc.
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    The molecular structure of N-hydroxyurea (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 971-974 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio calculations were performed on the tautomers and conformers of N-hydroxyurea using a 6-31G** basis set. The minimum-energy structures have been found and the importance of the intramolecular hydrogen bond as the stabilizing factor was pointed out. © 1996 John Wiley & Sons, Inc.
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    Masthead (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560570501
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    List of participants (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 985-1018 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560570502
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  • 59
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    Approach to nonadiabatic transitions by density matrix evolution and molecular dynamics simulations (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 975-983 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Many biological processes are characterized by an essentially quantum dynamical event, such as electron or proton transfer, in a complex classical environment. To treat such processes properly by computer simulation, allowing nonadiabatic transitions involving excited states, we recently developed a density matrix evolution (DME) method [H. J. C. Berendsen and J. Mavri, J. Phys. Chem, 97, 13464 (1993)] which simulates the dynamics of quantum systems embedded in a classical environment. The formalism of the method is presented and an overview of the applications ranging from collisions of a quantum harmonic oscillator with noble gas atoms to proton tunneling in a double-well hydrogen bond is given. The methodology for treatment of proton-transfer processes with inclusion of excited states is presented. Future application of the method on biologically interesting processes, such as proton transfer in enzymatic reactions, is discussed. © 1996 John Wiley & Sons, Inc.
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    Interpolant polynomial technique applied to the PPP model. I. Asymptotics for excited states of cyclic polyenes in the finite cyclic Hubbard model (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 1019-1031 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For theoretical reasons, and on account of the development of a new interpolation technique, it is useful and important to examine the asymptotic behavior of the solution to the one-dimensional Hubbard model. In this article, it is shown how perturbative expansions for the energy can be developed in the asymptotic region of the relevant coupling for all the relevant excited states of cyclic polyene rings. © 1996 John Wiley & Sons, Inc.
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    A BSSE-free SCF algorithm for intermolecular interactions. III. Generalization for three-body systems and for using bond functions (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 1049-1055 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The simple BSSE-free SCF method (CHA/F) introduced in the previous parts of this series is extended to the case of three subsystems, which may be either three weakly interacting molecules or a bimolecular system described by using bond functions. The CHA/F formalism is formulated in a more transparent manner, indicating also a straightforward way for generalization to the case of an arbitrary number of subsystems. The illustrative calculations show the viability of using the CHA/F scheme for three-component systems. © 1996 John Wiley & Sons, Inc.
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    Interpolant polynomial technique applied to the PPP model. II. Testing the interpolant technique on the Hubbard model (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 1033-1048 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: One is often led, in quantum mechanics, to a perturbative solution of an eigenvalue problem, which is defined by a given Hamiltonian. The perturbative series for the energy which results will be a function of a coupling constant which appears in the Hamiltonian. In this article, the perturbative series for the energy of a state of a cyclic polyene ring which are valid for the small and large coupling limit of the model are used to construct algebraic functions. These algebraic functions are defined in terms of polynomials which are given as a function of the energy variable and coupling parameter and can be solved to give the energy as a function of coupling. It is found that relatively small polynomials give very good agreement with the exact values and that the accuracy of the results increases rapidly as the degree of the polynomial increases. The final goal of this and subsequent articles is to study energy levels in PPP models of planar conjugated hydrocarbons. In this article, we test an interpolant technique on the case of the one-dimensional Hubbard model, where an exact solution can be obtained by solving a system of nonlinear equations. In the case of the Hubbard model, the correlation effects are overestimated. Therefore, if the technique works for the Hubbard model, it is reasonable to assume that the technique would work even better for the PPP model. © 1996 John Wiley & Sons, Inc.
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    Spin-free quantum chemistry. XXVI. The Ising, small-bipolaron theory of cuprate superconductivity (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 1057-1066 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Ising, small-bipolaron (ISB) theory is a strong-coupling theory of cuprate superconductivity which is based on the negative-U, Hubbard Hamiltonian. Its ground state is composed of (small) bipolarons and (small-bipolaron) holes with a vibronically induced, bipolaron-hole exchange interaction, JBH, between them. The energy gap, Δ(0), is taken to be equal to the dissociation energy of a small bipolaron and which, since it is defined spectroscopically, is not an order parameter. The application of the Ising mean-field theory to the highly degenerate ground-state yields a second-order phase change with kTC/2 = JBH and a real order parameter, Ω(T), which is valid over the entire temperature range from zero to TC. Near TC, the Ising free-energy functional takes the same form as does the Landau. In the presence of an electromagnetic field, the Ising functional is a generalization of the Ginzburg-Landau functional which employs a complex order parameter and which is invariant under the electromagnetic gauge transformation. The breaking of the gauge invariance yields the London theory of superconductivity. © 1996 John Wiley & Sons, Inc.
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    Solvatochromism of the π* ← n transition of acetone by combined quantum mechanical - classical mechanical calculations (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 1067-1076 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solvent shift of the π* ← n transition of acetone in water, acetonitrile, and tetrachloromethane was calculated in a combined quantum mechanical - classical mechanical approach, using both dielectric continuum and explicit, polarizable molecular solvent models. The explicit modeling of solvent polarizability allows for a separate analysis of electrostatic, induction, and dispersion contributions to the shifts. The calculations confirm the qualitative theories about the mechanisms behind the blue shift in polar solvents and the red shift in nonpolar solvents, the solvation of the ground state due to electrostatic interactions being preferential in the former, and favorable dispersion interaction with the excited state, in the latter case. Good quantitative agreement for the solvent shift between experiment (+1,700, +400, and -350 cm-1 in water, acetonitrile, and tetrachloromethane, respectively) and the explicit solvent model (+1,821, +922, and -381 cm-1) was reached through a modest Monte Carlo sampling of the solvent degrees of freedom. A consistent treatment of the solvent could only be realized in the molecular solvent model. The dielectric-only model needs reparameterization for each solvent. © 1996 John Wiley & Sons, Inc.
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    Model potentials in studies of atomic electron density distribution (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 1097-1106 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In density functional theory (DFT), a many-electron problem for the electron density in atoms may be reduced, according to the Kohn-Sham scheme, to a one-electron problem. In the present work, a variational model is proposed which leads, within some assumptions, to the set of equations describing the change of the electron density ρ and energy ε during the ionization process. It is shown that the one-electron density contributions are not necessarily spherically symmetric, but assume the symmetry which depends upon the symmetry of the positive field. A few nonspherically symmetric potentials are studied in the present article. The nonlinear differential equation for density r is formulated and solved for Coulombic, Fues-Kratzer, and Hartmann potentials. The solutions and some particular examples are presented. © 1996 John Wiley & Sons, Inc.
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    Ab initio studies on the mechanism of the fluoroketene-imine cycloaddition reaction: Via a gauche or trans intermediate (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 1107-1114 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cycloaddition reaction of FCH(double bond)C(double bond)O and NH2CH(double bond)NH leading to 2-azetidinone was studied theoretically at the level of RHF/6-31G and RHF/6-31G*. Two possible mechanisms via a gauche or trans intermediate were compared. The obtained results show that the reaction proceeds in a gauche manner much easier than in a trans one. © 1996 John Wiley & Sons, Inc.
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    Asymptotic behavior of electron densities and computation of one-electron properties (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 1077-1096 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The role of the asymptotic behavior of approximating sequences of electron densities ρn(r) in the calculation of one-electron properties is studied. Rigorous mathematical results in the frame of Hilbert spaces are used to prove the following facts: (i) Both the L2 convergence of wave functions ψn and the E convergence of the corresponding energies En guarantee the correctness of the limiting procedure limn→x ∫Ω s((overline)x(/overline)|ψn|2 d(overline)x(/overline) = ∫Ω s((overline)x(/overline))|ψ|2 d(overline)x(/overline) for the most frequently used operators s(x), Ω being any bounded region of the n-particle configuration space R3N; and (ii) the uniform boundedness of the sequence {ρn} together with both the L2 and E convergencies is sufficient to guarantee the correctness of the limiting procedure limn→x ∫∞0 s(r)ρnr2dr = ∫x0 s(r)ρr2 dr for most one-electron operators s(r) including the power moment operators rk which, for large k, are representative of the class of operators not relatively form-bounded by the Hamiltonian. The mathematical concept of uniform boundedness is used to give a characterization of the capability of {ρn} to reproduce the asymptotic behavior of the true electron density ρ and it is shown by means of numerical examples how a sequence {ρn} that does not reproduce the correct asymptotic behavior is not uniformly bounded and can give divergent expectation values of one-electron operators s(r) not relatively form-bounded by the Hamiltonian. © 1996 John Wiley & Sons, Inc.
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    Cluster models of ionic crystals: Band gaps (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 1115-1119 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We performed electronic ab initio calculations of ion clusters simulating a piece of ionic crystal. Our main interest here is to estimate the (direct) energy band gap from the cluster energy levels. The model consists of a central cation surrounded by four shells of ions, with additional point charges embedding the cluster. We present results for the series of alkali halides with rock-salt structure. © 1996 John Wiley & Sons, Inc.
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    Masthead (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560570601
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    Announcement (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 1133-1133 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560570603
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    Quantum mechanics in chemistiy, G. C. Schatz and M. A. Ratner, Prentice Hall, Englewood Clifs, New Jersey, 1993 (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 1131-1131 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560570602
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    The electronic structure of intrinsic defects at TiO2 (110) surfaces: An ab initio molecular orbital study (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 57 (1996), S. 1121-1129 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We report on an isolated cluster approach to determine local electronic structures of TiO2 surfaces before and after formation of intrinsic defects, i.e., oxygen vacancies, at different crystallographic sites. In particular, isolated oxygen vacancies at bridging sites, isolated oxygen vacancies at in-plane sites and aggregated oxygen vacancies at bridging sites have been treated which lead to changes in the coordination of the adjacent Ti atoms. We find that electronic band gap states are only formed in the presence of fourfold coordinated Ti surface atoms. © 1996 John Wiley & Sons, Inc.
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    Generalized Rabi oscillations in a three-level metastable system under periodic and quasiperiodic perturbations (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 3-10 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The quantum dynamics of prototypical three-level metastable system under external perturbations, both time-independent and time-dependent, are studied numerically as well as analytically. The regular Rabi oscillations generated in the system under a monochromatic perturbation are shown to develop additional features when the system has a metastable state. The autocorrelation function of ψ(t) reveals nondecaying, almost quasiperiodic, behavior in such systems. The Rabi oscillations turn more complex when a bichromatic perturbation with two incommensurate frequencies is allowed to interact with the three-level system, irrespective of the presence or absence of a metastable state. A rapid decay in the autocorrelation function of the wavefunction [ψ(t)] is observed in such cases. © 1996 Wiley & Sons, Inc.
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    Monotonicity properties of the atomic charge density function (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 11-21 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The present knowledge of the monotonicity properties of the spherically averaged electron density ρ(r) and its derivatives, which comes mostly from Roothan-Hartree-Fock calculations, is reviewed and extended to all Hartree-Fock ground-state atoms from hydrogen (Z = 1) to uranium (Z = 92). In looking for electron functions with universal (i.e., valid in the whole periodic table) monotonicity properties, it is found that there exist positive values of α so that the function go(r; α) = ρ(r)/rα is convex, and g1(r;α) = -ρ′(r)/rα is not only monotonically decreasing from the origin but also convex. This is, however, not the case for the function g2(r; α) = ρ′(r)/rα. Additionally, the conditions which specify values for β such that the function gn(r; β) = (-1) ′ρ(n)(r)/rβ is logarithmically convex are obtained and numerically calculated for n = 0,1 in all neutral atoms below uranium. The last property is used to obtain inequalities of general validity involving three radial expectation values which generalize all the similar ones known to date, as well as other relationships among these quantities and the values of the electron density and its derivatives at the nucleus. © 1996 John Wiley & Sons, Inc.
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  • 75
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    Vibrational-rotational levels and Franck-Condon factors of diatomic molecules via Morse potentials in a box (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 23-28 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pekeris' solution for vibrational-rotational levels of the Morse potential includes the unphysical domain - ∞ 〈 r 〈 0 of the internuclear separation, just like Morse's solution for vibrational levels. In this article, the method of confinement in a box is implemented to obtain the vibrational-rotational J = 1 levels of Morse potentials in the physical domain 0 〈 r 〈 ∞, as well as the corresponding Franck-Condon factors. Applications to Li2 and AIO are presented as illustrations. © 1996 John Wiley & Sons, Inc.
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  • 76
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    Symmetry breaking and electron correlation in O2-, O2, and O2+: A comparison of coupled cluster and quadratic configuration interaction approaches (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 29-39 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Potential energy curves are calculated for O2-, O2, and O2+ at the CCSD, QCISD, CCSD(T), and QCISD(T) levels of theory using aug-cc-pVDZ and aug-cc-pVTZ basis sets with electron correlation built onto inversion symmetry constrained and relaxed UHF wave functions. The spectroscopic constant re, we, we, xe, Dj, and αe, are determined from the potential curves using standard second-order perturbation theory expressions and are compared with experimental values to assess the relative accuracy of the theoretical approaches. Comparison of corresponding symmetry-constrained and symmetry-relaxed calculations indicates that the CCSD method is generally superior to CCSD(T), QCISD, and QCISD(T) in recovering from a symmetry-broken reference function. © 1996 John Wiley & Sons, Inc.
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  • 77
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    A study of nitrogen oxides by using density functional theory and their comparison with ab initio and experimental data (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 41-46 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio and density functional theory (DFT) methods have been applied to generated geometries of chemical systems built only from nitrogen and oxygen. The results of hybrid, local, and nonlocal DFT methods were compared with ab initio HF and MP2 methods. The suitability of DFT methods for modeling nitrogen-oxygen chemical systems is discussed. © 1996 John Wiley & Sons, Inc.
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    Methanediol decomposition mechanisms: A study considering various ab initio approaches (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 47-55 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The alternative decomposition reactions CH2(OH)2 → CH2O + H2O and CH2(OH)2 + H2O → CH2O + 2H2O are investigated using the semiempirical PM3 as well as the ab initio HF/3-21G, HF/6-31G, HF/6-31G**, and MP2/6-31G** calculations. Reactants, products, and appropriate transition states are located on corresponding potential energy surfaces and compared with those reported in earlier studies. © 1996 John Wiley & Sons, Inc.
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  • 79
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    Nonperfect synchronization of bond-forming and bond-rupturing processes in the reaction Ḣ + H2 → H2 + Ḣ (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 57-65 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The simplest prototypical hydrogen transfer reaction, i.e., Ḣ+ H2 → H2 + Ḣ, is studied by the quantum-mechanical ab initio methods. Results reveal that during this reaction free valence which almost equals the square of the spin density develops on the migrating hydrogen atom. Bond orders are calculated using Mayer's formalism. Both the variations of bond orders and bond lengths along the reaction path are examined. Our analysis reveals that the bond formation and bond cleavage processes in this reaction are not perfectly synchronous. The bond cleavage process is slightly more advanced on the reaction path. © 1996 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 80
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    Quantum mechanical models for organometallic reactivity (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 67-84 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general scheme for theoretical treatment of organometallic reactivity is proposed. It is based upon the notion that the reactivity of a molecule is strongly affected by its coordination to metal-containing fragments. Based upon this idea we describe the large-scale organometallic reactions as reactions of the ligands in the coordination spheres of transition metal complexes. We propose here a quantum mechanical framework for analysis of effects of coordination on the reactivity and give several examples of qualitative energy profiles for reactions in the ligand spheres of transition metal complexes. © 1996 John Wiley & Sons, Inc.
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  • 81
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    Basis sets for ab initio periodic Hartree - Fock studies of zeolite/adsorbate interactions: He, Ne, and Ar in silica sodalite (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 60 (1996), S. 809-820 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Silica sodalite is an ideal model system to establish base-line computer requirements of ab initio periodic Hartree-Fock (PHF) calculations of zeolites. In this article, we investigate the effect of various basis sets on the structural and electronic properties of bulk silica sodalite. We also study the interaction of He, Ne, and Ar with the sodalite cage. Our work shows that basis-set superposition errors (BSSE) in calculations using STO-3G and 6-21G(*) basis sets are as large as the interaction energies, leading to poor confidence in the results. To cure this problem, we present high-quality basis sets for Si, O. He, Ne, and Ar, optimized for use with PHF methods, and demonstrate that the new basis set greatly reduces BSSE. The theoretical barriers for transfer of the rare gases between sodalite cages are 5.6, 13.2, and 62.1 kcal/mol for He, Ne, and Ar. © 1996 John Wiley & Sons, Inc.
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  • 82
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    Semiempirical Hamiltonians for spatially confined π-electron systems (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 60 (1996), S. 971-981 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A study of π-electron systems confined by impenetrable surfaces is presented. The study results in a nonempirical-based approach to obtain confinement-adapted semiempirical π-Hamiltonians including repulsive terms (PPP or Hubbard). The impenetrable surface confinement of a physical system involves changes in the boundary conditions that the eigenvectors of its differential Hamiltonian operator have to fulfill, while the Hamiltonian itself remains unchanged. However, if this Hamiltonian is written in second quantization language, then confinement only involves changes of the Hamiltonian scalar factors (integrals). Semiempirical Hamiltonian integrals are replaced by parameters; therefore, confinement involves only changes of these parameters. It is shown that confinement changes Coulomb (αi) and exchange (βij), while repulsion (γij) parameters remain unaffected. Next, the influence of confinement upon the electron correlation of (i) π-electron molecular systems, (ii) atoms, and (iii) an electron gas is discussed. The behaviour of the correlation energy vs. the confinement size is found to be different for each type of system. A neat explanation of this variety is given in terms of the Coulomb attractive fields of the systems. Some chemical confinement effects such as an increase in the reactivity of π-electron systems is also outlined. © 1996 John Wiley & Sons, Inc.
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  • 83
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    Post-Hartree-Fock and DFT level studies on the Cl2CO … Cl2 complex: Accurate molecular parameters, harmonic vibrational frequencies, and interaction energiesPresented at the 1995 Sanibel Symposium. (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 60 (1996), S. 1007-1013 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Cl2CO … Cl2 complex was studied using ab initio post-Hartree-Fock theory at the MP2 and MP4 levels and, for comparison, the DFT method with 6-311G(2d), 6-311 + G(2d), and Sadlej's medium-size polarized (MSPBS) basis sets. A potential energy search recovered a planar minimum-energy structure characterized by a bent conformation. For this weakly bound complex, the interaction energy corrected for the basis set superposition error amounted to - 0.88, - 1.09, - 1.43, and - 0.38 kcal/mol at the MP4(SDTQ)/6-311G(2d), MP4(SDTQ)/6-311 + G(2d), MP4(SDTQ)/MSPBS, and DFT(Becke3LYP)/6-311 + G(2d) levels of theory, respectively. Two highly symmetrical forms, linear and T-shaped, correspond to transition-state conformers. The analysis of harmonic vibrational frequencies and potential energy distribution was performed at the MP2 and DFT levels with the 6-311 + G(2d) basis set. © 1996 John Wiley & Sons, Inc.
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  • 84
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    Selection of basis sets for atoms and molecules in cavities (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 60 (1996), S. 993-999 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method of selection of basis functions for the quantum chemical description of atoms and molecules inside spherical and cuboidal cavities is presented. The method consists of two independent steps. First, the appropriate GTO or STO exponents are chosen by fitting the basis functions to cutoff orbitals. The criterion of maximal orbital density inside the cavity is next applied to form the final model orbital space. The method presents the fundamental advantage over many other methods of being trivially applicable in standard quantum chemical progam packages. As an illustration, the method is applied to the hydrogen atom in a spherical box. The use of contracted basis functions is also discussed. © 1996 John Wiley & Sons, Inc.
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  • 85
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    Analysis of electrostatic and hydrophobic complementarities between chymotrypsin and avian ovomucoid third domains using molecular electrostatic potential: Effect of residue replacements (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 60 (1996), S. 1081-1091 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electrostatic and hydrophobic complementarities between chymotrypsin and its inhibitor, avian ovomucoid third domains, were evaluated for eight species, which have different amino acid sequences, using molecular electrostatic potential (MEP) and MEP correlation, and the enzyme-inhibitor interaction was analyzed. The changes in the electrostatic and hydrophobic complementarities caused by the amino acid replacements were reflected clearly in the calculated MEP correlation, and it explained the observed binding association constants correctly. The electrostatic complementarity due to arginine at P′3 strongly promotes the binding process of the inhibitor, while the hydrophobic complementarity in the P1 and P′2 positrons also affects the binding process. It was demonstrated that our method is an effective molecular modeling tool in drug design and protein engineering. © 1996 John Wiley & Sons, Inc.
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  • 86
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    Atomic shell structure and electron numbers (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 60 (1996), S. 875-882 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron localization function (ELF) was calculated for the atoms Li to Sr. The ELF maxima reveal the atomic shell structure for all these atoms. The shells are separated from each other by ELF minima. The integration of the electron density in a shell gives electron numbers. For the valence shell those are in good agreement with the ones expected from the Periodic Table of Elements. © 1996 John Wiley & Sons, Inc.
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  • 87
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    Computation of electronic molecular polarizabilities by a variational method at the CISD level (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 60 (1996), S. 883-895 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The variational method proposed earlier has been generalized, using a trial function of the form: ψ = (Λ0 + ΣsΛsms)ψ0 in which ms = r2p+1Cml, s standing for a triplet (p, l, m) and implemented into the program Hondo-8.4. The second-order density matrices are used to take into account the mono and bi-excited states (DM1 and DM2 matrices, GUGA Algorithm). This allows us to compute the dipole (α), dipole-quadrupole (A) and quadrupole (C) polarizability tensors at the CISD level. The results obtained for a series of test molecules: CO, HF, NH3, and methane with various gaussian basis sets are compared with experimental results (when available for A and C) and those obtained with other theoretical methods. The correlation is found to lower the values of the dipole polarizability which was generally too high when computed by the variational method at the RHF level and the values obtained here are in good agreement with the experimental ones. © 1996 John Wiley & Sons, Inc.
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  • 88
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    List of participants. 1995 Joint NSF-CECAM workshop on combined quantum mechanical and molecular mechanical potentials for simulation of biomolecules (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 60 (1996), S. 1097-1100 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560600603
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    On some ways of modifying semiempirical quantum chemical methods (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 175-184 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The problems of semiempirical quantum chemical calculations of (a) spin densities in paramagnetic organometallics, (b) hydrogen bonds, and (c) bond energies and the structure of transition-metal compounds are discussed. Some modifications of the existing semiempirical quantum chemical method are presented. An extended NDDO approximation has been developed. This scheme includes explicit symmetric orthogonalization of the core Hamiltonian and the use of Hellmann's effective core potential for core-electron interaction. © 1996 John Wiley & Sons, Inc.
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  • 90
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    Calculations of molecules, clusters, and solids with a simplified LCAO-DFT-LDA scheme (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 185-192 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simplified LCAO-DFT-LDA scheme for calculations of structure and electronic structure of large molecules, clusters, and solids is presented. Forces on the atoms are calculated in a semiempirical way considering the electronic states. The small computational effort of this treatment allows one to perform molecular dynamics (MD) simulations of molecules and clusters up to a few hundred atoms as well as corresponding simulations of condensed systems within the Born-Oppenheimer approximation. The accuracy of the method is illustrated by the results of calculations for a series of small molecules and clusters. © 1996 John Wiley & Sons, Inc.
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    Masthead (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996) 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560580201
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  • 92
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    Nonempirical wave functions for very large molecules. I. The PRDDO/M method (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 193-202 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We describe enhancements to the method of partial retention of diatomic differential overlap (PRDDO). The new method, denoted PRDDO/M, employs a basis set of not quite orthogonal atomic orbitals (NQOAOS) and utilizes sparse matrix techniques to greatly increase the computational efficiency for large molecules. Other modifications, including a complete reparametrization of the method against ab initio STO-3G calculations and implementation of integral screening/damping algorithms, are described. The method is an order of magnitude or more faster than are STO 3G single-point calculations using modern ab initio codes, with little loss in accuracy. © 1996 John Wiley & Sons, Inc.
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    Preface (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 121-121 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560580202
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  • 94
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    Relativity and the chemistry of UF6: A molecular Dirac - Hartree - Fock - CI study (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 203-216 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electronic structure and bonding of UF6 and UF6- are studied within a relativistic framework using the MOLFDIR program package. A stronger bonding but more ionic molecule is found if one compares the relativistic with the nonrelativistic results. The first peak in the photoelectron spectrum of Karlsson et al. is assigned to the 12γ8u component of the 4t1u orbital, in agreement with other theoretical and experimental results. Good agreement is found between the experimental and theoretical 5f spectrum UF6-. Some properties, like the dissociation energy and electron affinity, are calculated and the necessity of a fully relativistic framework is shown. The Breit interaction has an effect on the core spinors and the spin-orbit splitting of these spinors but the influence on the valence spectrum is negligible. © 1996 John Wiley & Sons, Inc.
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    Announcement (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 217-217 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No Abstracts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560580203
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  • 96
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    Comments on the topic “computation of large molecules” (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 219-240 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quantum chemical and molecular modeling computations on large molecular systems are defined for the computational facilities assumed to be available from now to the next 4 years. We considered a few topics which are requiring much attention. The correlation energy is discussed in some detail and we have presented two new functionals, called the J-functional and the K-functional, which make use of Coulomb or exchange-type integrals. In addition, we report new computational results for the Coulomb-Hole-Hartree-Fock approximation. Very brief summaries on new developments in relativistic Dirac-Fock computation and in density functional theory, on the advantages gained by using different basis sets in the same computation, and on the promises of parallel computing conclude the article. © 1996 John Wiley & Sons, Inc.
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    Size and shape dependence of the electrostatic potential in cluster models of the MgO(100) surface (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 241-250 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We investigated the dependence of the electrostatic potential on the size and the shape of various cluster models of the MgO(100) surface. Both Mg2+ and O2- adsorption sites have been considered. The clusters were embedded in a large array of point charges to provide a representation of the Madelung potential. We found that the electrostatic potential in the adsorption region shows a marked dependence on the size of the cluster, in particular, for non-stoichiometric clusters where the number of cations and anions differs considerably. These oscillations are due to (a) the different contribution to the electrostatic potential given by a point charge or by an extended ion, and (b) by the polarization of the ions at the cluster border. The effect of the oscillations in the electrostatic potential on the chemisorption properties was investigated for the case of CO2 interacting with surface and defect O2- sites of the MgO surface. © 1996 John Wiley & Sons, Inc.
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  • 98
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    Mixed quantum - classical calculations on the water molecule in liquid phase: Influence of a polarizable environment on electronic properties (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 251-265 
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    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electronic properties of a water molecule embedded in a water droplet are studied in the framework of the generalized self-consistent reaction field approach, using ab initio Hartree-Fock and configuration interaction wave functions. Electrostatic and inductive effects of the surrounding water molecules were calculated with the help of configurations drawn from a classical molecular dynamics simulation. Basis-set effects and solute-solvent interaction operator representation are examined. Embedding energies and liquid-phase multipole moments obtained from the present mixed quantum-classical model are compared with corresponding quantities for purely classical water models. © 1996 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 99
    Electronic Resource
    Electronic Resource
    Standard and direct methods in ab initio Hartree-Fock calculations: Application to polyoxometallates, organometallic clusters, and polypeptides (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 267-281 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article describes the present status of the program system ASTERIX and its move toward an efficient implementation on distributed memory computers with 128 processors or more. The ASTERIX program is currently used for scf and ci calculations on what we consider to be truly large systems; polyoxometallates, metallocarbohedrenes, organometallic clusters, and polypeptides. A brief review of our projects in those fields, either recently achieved or in progress, is provided. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 100
    Electronic Resource
    Electronic Resource
    Extension of semiempirical methods to simulation of surfaces (1996)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 58 (1996), S. 283-295 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various approaches for surface simulation are described. They are based on free, saturated, and embedded clusters, as well as periodic models. The features of semiempirical methods are reviewed and ideas for their improvement are discussed. Special features of the structure and stability of clusters are presented which are suitable for the transition to the solid state. Linear and nonlinear relationships for binding energies and bond lengths in dependence of the average coordination number are discussed. Finally, a systematic way for the simulation of adsorption at ion crystal surfaces by model clusters is suggested. © 1996 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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