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  • 1980-1984  (433)
  • 1970-1974  (194)
  • 1981  (433)
  • 1972  (194)
  • Computational Chemistry and Molecular Modeling  (446)
  • Electron microscopy  (181)
  • Nuclear reactions
Material
Years
  • 1980-1984  (433)
  • 1970-1974  (194)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Rheumatology international 1 (1981), S. 21-28 
    ISSN: 1437-160X
    Keywords: Rheumatoid nodules ; Polymorphonuclear granulocytes ; Electron microscopy ; Collagen degradation products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Necrotic areas of rheumatoid nodules were investigated electron microscopically. PMNs in different stages of disintegration were present in all cases. Granular material, sometimes in a fiberlike orientation, and small fibrils without periodicity were detected between the collagenous fibers. It is assumed that granular material and fibrillar remnants represent degraded collagen. Often these degradation products were present in the neighborhood of disintegrating PMNs. From this morphological relationship it is concluded that enzymes of PMNs may in part be responsible for the fibrinoid necrosis in rheumatoid nodules.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0711
    Keywords: Ovary ; FSH ; Inhibin ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of a highly purified preparation of human follicular fluid inhibin (hFF-Inhibin) on the ovary of immature rats have been studied. The highly purified preparation was obtained by gel and ion-exchange chromatography and ultrafiltration of the acetone dried extract of human follicular fluid. Administration of 5, 10, or 20 μg of inhibin daily for 10 days starting from day 11 postnatum resulted in (1) a significant reduction of basal FSH levels by the 20 μg dose but not by lower doses, (2) atresia of preantral and antral follicles in an apparently dose-related manner, (3) hyperplasia of the theca interna, and (4) degeneration of the granulosa cells, maximum damage being in the group treated with 20 μg. In inhibin-induced atretic follicles there were no signs of (a) granulosa cell-luteinisation, (b) connective tissue invasion, (c) hyalinisation of the basement membrane, or (d) vascularisation. Simultaneous administration of human menopausal gonadotrophin (hMG) led to luteinisation of the atretic follicles. However, the other structural alterations mentioned above (b-d), and those of the theca cells could not be overcome by hMG. In addition, there was no significant difference in the ovarian weight of animals treated with hMG when compared to those treated with inhibin and hMG, but the serum levels of the oestradiol in the latter were significantly lower. Our results suggest that hFF-inhibin acts not only at the pituitary, but also at the ovarian level.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2307
    Keywords: Liver biopsy ; Renal transplant recipients ; HBs and HBc Ag ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A prospective series of 45 liver biopsies taken from 22 renal transplant patients was investigated for the presence of hepatitis B antigen core (HBc) and surface (HBs) components by electron microscopy. At the time of each biopsy serum HBs Ag was sought by radioimmunoassay. Sections were taken for the detection of HBs Ag by immunofluorescence. In seropositive patients, intravesicular tubular structures resembling HBs Ag were found in 61% of biopsies while the intranuclear core HBc was present in 69%. No correlation could be made between the ultrastructural pattern of the viral components and the intensity of the histological liver damage. During the follow up, there was an accumulation of both HBs and HBc Ag even in a period as short as 1 year. The 9 liver specimens examined after three years of transplantation showed a marked accumulation of both antigens. Thus the expression of HB Ag at the hepatocellular level seems to correlate better with the duration of antigenaemia than with the histological pattern. Lastly, on matched semithin and ultrathin sections, the ground glass appearance of cytoplasm appeared to correlate with smooth endoplasmic reticulum distorsion, irrespective of the simultaneous presence or absence of intravesicular tubular structures. The sanded nuclei expressed a rare massive accumulation of core antigen.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 391 (1981), S. 165-175 
    ISSN: 1432-2307
    Keywords: Dermatofibrosarcoma protuberans ; Tissue culture ; Electron microscopy ; Fibroblasts ; Fibrosarcoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Dermatofibrosarcoma protuberans has been considered to be of fibrohistiocytic or fibroblastic origin. The purpose of this paper is to identify the original cell strain from which this neoplasm derives, using tissue culture and electron microscopic methods. Thirteen cases of DFSP characterised by clinical, topographical, histological and behavioral criteria were explanted. The emigrating cells were bipolar with two opposed processed and showed a radial arrangement in respect to the expiants. After the second week the distal processes tended to curve back towards the cell body forming flame-like structures. This cell morphology and cellular orientation persisted during the whole life of the culture. Electron microscopy was performed in three cases; the newly grown cells maintained an electron microscopic picture similar to that found in the original tumors. This pattern of behaviour is characteristic of fibroblastic tumors and has been found in explants of normal fibroblasts, of fibromatosis and of fibrosarcomas used as controls. On this basis, we believe that DFSP is a fibrosarcoma of the skin of low grade malignancy.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 390 (1981), S. 11-21 
    ISSN: 1432-2307
    Keywords: Electron microscopy ; Bladder neoplasms ; Measurement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of urothelium from 4 patients with no evidence of tumour was compared with that taken from 22 patients with bladder neoplasms of different grade and stage. Two features were quantified: the percentage of reduplication of the basal lamina and the percentage of discontinuous basal lamina. Tumours showed a lower percentage of reduplicated basal laminae than normal tissues, the difference being significant in 3 out of 4 types of tumours. The difference in frequency between normal tissues and non-recurring tumours was not significant, but there was a significant difference between normals and recurring tumours. All types of tumours showed discontinuities in the basal lamina, including 80% of those staged non-invasive by light microscopy. None of the normal tissues showed these. The percentage of discontinuities seen in non-recurrent tumours was half that seen in recurrent ones, but both groups were significantly higher than normals. Loss of continuity of the basement membrane distinguishes invasive from non-invasive tumours. However, there is a high probability of these being missed by light microscopy alone. Therefore, electron microscopic studies on recurrent bladder tumours would increase the accuracy of staging and prognosis.
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  • 6
    ISSN: 1432-2307
    Keywords: Microfold (membraneous) cells ; Tuft cells ; Electron microscopy ; Horseradish peroxidase ; Sequential uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 79 NMRI mice and Wistar rats were used for ultrastructural investigations of the sequential uptake of horseradish peroxidase (HRP) by M cells. In addition the ultrastructure of the so-called tuft-cells was reported. HRP, a foreign protein antigen, was applied either by injection (Owen 1977), or by stomach tube. After variable exposure times (5 min to 3 h) segments of the distal small intestine, containing Peyer's patches, mesenteric lymph nodes and liver tissue were removed. After fixation, they were reacted with H2O2-3,3′-diaminobenzidine tetrachloride and were examined by light and electron microscopy for HRP reaction products. The uptake of HRP mainly occurs through the M cells in the dome epithelium of Peyer's patches with a continual transport of the antigenic material into lymphoid cells, macrophages, and dendritic reticulum cells. In the 3 h specimens a few single HRP-positive lymphoid cells can be observed within the efferent lymphatics of Peyer's patches. In addition, a continual uptake of HRP by necrobiotic enterocytes was observed. It has also been shown that after 3 h HRP is located inside the Kupffer cells of the liver. These findings also support the presumption that antigenic material can be transmitted via the portal circulation. However, definite, quantitatively and permanently recorded uptake of HRP by brush border cells was not be observed. To exclude a toxic effect of the applied HRP on the enterocytic epithelium additional resorptive-physiological investigations were performed using the in vivo-perfusion-recirculation method and in vitro-accumulation of L-phenylalanine.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 391 (1981), S. 107-115 
    ISSN: 1432-2307
    Keywords: Hemangioendothelioma ; Esophagus ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The histology and electron-microscopy of a malignant hemangioendothelioma of the esophagus wall appearing in a 42 year old male is presented. By light microscopy the tumor is composed of vessels and capillary-like structures of an anastomosing nature covered by atypical endothelial cells. These cells infiltrate the intersticial spaces growing into the posterior mediastinal area. Electron microscopy confirms the endothelial nature of the neoplastic cells, showing characteristics of the cell type, as is the presence of Weibel-Palade bodies, filaments and active pinocytosis. Hemangioendothelioma should be differentiated from other vascular tumors (angiosarcoma) as are hemangiopericytoma or hemangioblastoma, being composed exclusively of malignantly transformed endothelial cells.
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  • 8
    ISSN: 1432-2307
    Keywords: Crohn's disease ; Electron microscopy ; Ultracytochemistry ; Immunohistology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Immunohisto- and ultracytochemical studies were carried out on surgical and biopsy specimens from 27 patients suffering from Crohn's disease of the ileum or colon. Control specimens were obtained from 16 patients with nonspecific proctitis or neoplastic disorders of the caecum or rectum. Our results suggest that the initial lesions in Crohn's disease are associated with a typical humoral immune response. In non-ulcerated mucosa a uniform increase of IgA-, IgG- and IgM-cells was found (numbers of IgA-cells: IgG-cells ∼14.4), whereas disproportional increases of IgG- and IgE-cells were observed in ulcerated mucosa (IgA:IgG ∼0.7). The IgE-cell multiplication in ulcerated areas suggests the possibility of local hypersensitivity reactions. Macrophages and granulocytes contained IgG, which was also demonstrated in multinucleated giant cells. The granulomas contained extracellular IgG, acid phosphatase and peroxidase. The finding of potentially harmful extracellular lysosomal enzymes may be of pathogenetic significance in view of the hypothesis of Weissmann (1964). Micro-ulcerations of the dome epithelium of hyperplastic Peyer's patches were seen by electron microscopy a finding which can be interpreted as an early lesion through which luminal antigens gain uncontrolled access to Peyer's patches. This could lead to (1.) overstimulation of the local immune system, (2.) disturbance of local immune homeostasis, (3.) imbalanced Ig-production with disproportional increases in IgG and IgE. We were not able to detect Clq or C3 bound to epithelial or vascular basement membranes, and no electron dense deposits were found. Viral particles or bacteria in any of the specimens were not demonstrated by electron microscopy. The type of immune response in Crohn's disease and its pathogenetic significance with remain unclear until more is known about the specificity of the locally produced antibodies.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 392 (1981), S. 135-145 
    ISSN: 1432-2307
    Keywords: Malignant fibrous histiocytoma ; Sarcoma ; Soft tissue neoplasms ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructural findings in 17 cases of malignant fibrous histiocytoma (MFH) are described. The tumors consisted of fibroblast-like cells and histiocyte-like cells in different proportions in different cases. Intermediate, undifferentiated, xanthomatous and multinucleated giant cells were also identified. In 12 of 17 cases myofibroblasts were evident. Acid phosphatase activity was detected cytochemically in the Golgi zone, endoplasmic reticulum and lysosomes (GERL) mainly within histiocyte-like cells, in three cases. These observations indicate that the GERL of the tumor cells are engaged in the formation of lysosomes. The polymorphic cellular composition, including undifferentiated cells, lends support to the concept that the MFH originates from a primitive multipotent undifferentiated mesenchymal cell.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 392 (1981), S. 231-239 
    ISSN: 1432-2307
    Keywords: Bronchial gland adenoma ; Oncocytoma ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Benign adenomas derived from the bronchial mucous glands are uncommon. Probably the least common variety is the oncocytomatous adenoma, this case being the second known example. The tumour was situated in the right main bronchus in a man aged 75. An oncocytomatous adenoma should be clearly distinguished from the common oncocytomatous change which affects the normal bronchial mucous gland cells seen in adults. The eosinophilic, columnar tumour cells seen by light microscopy contained numerous and prominent mitochondria by electron microscopy and granules of serous secretion. Other tumour cells contained microfilaments and were perhaps of myoepithelial origin. The true oncocytomatous mucous gland adenoma needs to be distinguished from an oncocytomatous bronchial carcinoid tumour the cells of which contain dense core granules of neurosecretory type. The bronchial oncocytomatous adenoma appears to be a benign tumour with a close similarity to its counterpart occuring in the salivary glands.
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Virchows Archiv 394 (1981), S. 31-47 
    ISSN: 1432-2307
    Keywords: Blood vessel neoplasms ; Electron microscopy ; Histochemistry ; Angiosarcoma ; Breast neoplasms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A total of five haemangiosarcomata and two benign haemangiomas arising in the mammary gland have been studied electron microscopically and by histochemical techniques. Malignant tumors were mainly composed of endothelial cells reactive to alkaline phosphatase and adenosine triphosphatase, and of pericytes and undifferentiated mesenchymal elements. A juvenile haemangioma showed a more structured wall with an increase of endoplasmic reticulum and filaments, and a diminution of membrane modulations and rod-like tubular bodies. A cavernous haemangioma showed an ultrastructure very similar to normal vessels. The ultrastructural and histochemical data suggest a blood vessel origin of mammary angiosarcomas and show that vascular neoplasms of the breast, benign or malignant, are composed of a combined proliferation of the different cell types present in the vessel wall, as described in other organs.
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  • 12
    ISSN: 1432-2307
    Keywords: Labial salivary gland biopsy ; Gougerot-Sjögren's syndrome ; Clinico-pathology ; Histoenzymology ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 119 cases of Sjögren's syndrome are described. Clinically, the female sex predominates (83% of cases); the average age is 56 years. Isolated sicca syndrome is noted in 31 % of cases; it is more often associated with rheumatoid polyarthritis (64%) or with another collagen disease (5%). In addition, in 5 patients, we have found a malignant lymphoproliferative disease in an accessory or a main salivary gland (4 non-Hodgkin malignant lymphomas, 1 chronic lymphoid leukaemia). In all cases, a biopsy from accessory labial glands or from a main salivary gland, corroborates the diagnosis. Histologically, epi-myoepithelial islets are always lacking in accessory glands. We classified labial gland injuries in three groups based on striated duct distention: first, some tubular ectasia with interstitial lymphoid cells; second, much ectasia associated with many lymphoid cells and the beginning of pericanalar sclerosis; third, intensive ectasia, scarce lymphocytes, severe peri- and intralobular sclerosis and extensive destruction of acini. This grading is positively correlated with that of parotid biopsies and also with abnormalies on numerous parotid sialographic radiograms performed simultaneously. The histoenzymological study demonstrates decreased activity of oxydative enzymes in striated duct epithelia and of ATPases in myoepithelial cells. The ultrastructural study confirms these findings. Even at an early stage of the disease, tubular alterations are observed: epithelial cell degeneration (vacuolated mitochondria, loss of cytoplasmic lateral membrane foldings) and myoepithelial cell damage (in particular disappearance of myofilaments). These findings explain tubular ectasia by the loss of contractile function. Simultaneously, intensive regeneration from the intercalated ducts by young “totipotent” cells, sometimes differentiating into epidermoid, secretory or myoepithelial cells, are observed. Lesions in acinar cells are less marked: conglomeration of secretory granules, some autophagosomes and rarely true necrosis. In the interstitial tissue, amongst lymphocytes, plasmocytes and mastocytes, numerous myoepithelial cells are present: young pseudo-fibroblastic cells with poor ergastoplasm and some myoid organelles (a few myofilaments, dark zones and endocytosis vacuoles on cell membrane; degenerated myoepithelial cells whose scanty dark cytoplasm is filled with lipid droplets). Thus, by analogy with the myoepithelial islets observed in parotid biopsies, the myoepithelial cell damage seems to have a specific signification in Sjögren's disease. Regeneration from the intercalated ducts fails to repair these cells and to restore their physiological contractile function. Furthermore, this leads to extratubular migration of young myoid cells which are responsible for progressive accumulation in the interstitial tissue of membranoid material and later collagen sclerosis.
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  • 13
    ISSN: 1434-0879
    Keywords: Dog prostate ; Stereological analysis ; Electron microscopy ; Oestrogen effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The stromal tissue of the prostate in normal castrated dogs and castrated and oestrogen treated dogs were studied by quantitative morphological methods. Quantitative morphological (=stereological) procedures provide values of volume, surface and number of tissue and cell components. The stereological data show an activation of the smooth muscle cell of the stromal tissue in the oestrogen treated dog compared with the control group; related to the unit volume of smooth muscle cell cytoplasm, a threefold increase of the endoplasmic reticulum was observed in castrated and oestrogen treated dogs.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Research in experimental medicine 178 (1981), S. 165-175 
    ISSN: 1433-8580
    Keywords: Perfused rat pancreas ; Insulin secretion ; Uric acid ; Light microscopy ; Electron microscopy ; Rattenpankreasperfusion ; Insulinsekretion ; Harnsäure ; Lichtmikroskopie ; Elektronenmikroskopie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es ist bekannt, daß die Methylxanthine Coffein und Theophyllin die Insulinsekretion positiv beeinflussen. Im Rahmen von Perfusionsversuchen sollte untersucht werden, ob die Inselzellfunktion auch dem Einfluß der chemisch eng verwandten Harnsäure unterliegt. Zugleich sollte eine Destruktion von Inselzellstrukturen durch Harnsäure ausgeschlossen werden, da die chemisch ähnlich configurierte Substanz Alloxan bekanntlich Inselzellnekrosen verursacht. Dazu wurden isolierte Rattenbauchspeicheldrüsen mit Glukosekonzentrationen von 100 mg/100 ml und 300 mg/100 ml stimuliert. In einem Teil der Fälle wurde dem Perfusat Harnsäure in der Konzentration von 12 mg/100 ml zugegeben. Es zeigte sich, daß Harnsäure die Insulinsekretion bei Stimulation mit Glukose in der Konzentration von 100 mg/100 ml nicht beeinflußt. Werden die B-Zellen jedoch mit einer Glukosekonzentration von 300 mg/100 ml stimuliert, so steigert Harnsäure die Hormonfreisetzung im Sinne eines glukosepotenzierenden Effektes um mehr als 100%. Anhand charakteristischer Sekretionsphänomene sowie lichtoptischer und elektronenmikroskopischer Untersuchungen konnte nachgewiesen werden, daß es sich hierbei um eine echte Mehrsekretion handelt und nicht etwa um einen Auslaufeffekt als Folge einer Destruktion von Inselzellstrukturen durch eine alloxanähnliche Wirkung der Harnsäure.
    Notes: Summary Methylxanthines, such as caffeine and theophylline, show effects increasing the secretion of insulin. Perfusion experiments were intended to find out whether insulin secretion is even influenced by uric acid, which is chemically closely related. Besides, it was to be demonstrated that uric acid causes no damages to islet cell structures for it is well established that alloxan, which is chemically related to uric acid, produces necroses in B cells. Isolated rat pancreata were stimulated by glucose at concentrations of 100 mg/100 ml and 300 mg/100 ml. In part of the experiments uric acid was added to the perfusion medium at a concentration of 12 mg/100 ml. We found that uric acid has no influence on insulin secretion if it is stimulated by glucose at a concentration of 100 mg/100 ml. However, if B cells are stimulated by glucose at a concentration of 300 mg/100 ml insulin secretion is enhanced by the addition of uric acid by more than 100%. This indicates that this substance exhibits a glucose-potentiating effect. The characteristic dynamics of insulin secretion demonstrate together with light- and electron-microscopic investigations that uric acid causes a real additional secretion and no leaking of intracellular insulin as a result of destruction of islet cell structures by an effect of uric acid similar to that of alloxan.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 54 (1981), S. 203-210 
    ISSN: 1432-0533
    Keywords: Retina ; Schwann cell ; Myelinated nerve fibers ; Nodes of Ranvier ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Myelination of axons in the nerve fiber layer (NFL) of the retina occurs as a sporadic abnormality in several mammalian species including man, monkey, cat and rat. All of these species have vascularized retinae and, in the latter three, ultrastructural studies have demonstrated the pattern of medullation to be similar to Schwann cell myelination in the peripheral nervous system. This contrasts with an oligodendrocytic pattern of myelination normally present in the avascular retina of the rabbit. One possible explanation for this difference is that the pattern of myelination is related to the presence or absence of retinal blood vessels. The present investigation provides the first evidence of NFL myelination in another avascular retina, that of the guinea pig. Myelination in the guinea pig retina was observed in a single bundle of axons and involved only large diameter fibers. With several axons, myelin sheaths terminated at hemi-nodes of Ranvier and in all such cases this occurred in association with marked paranodal infolding. Morphological characteristics of the myelination include (1) a one to one relationship between axon and myelinating cell, (2) cytoplasm between myelin sheath and plasma membrane, (3) basal lamina surrounding the myelinating cell, (4) collagen fibers in the adjacent extracellular space and (5) double intraperiod lines. These morphological features are characteristic of peripheral nerve myelination by Schwann cells. Thus, in all species so far described in which retinal medullation is abnormally present, the pattern of myelination has been Schwann cell in nature rather than oligodendrocytic. The reasons for this Schwann cell predominance remain undefined.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 54 (1981), S. 233-237 
    ISSN: 1432-0533
    Keywords: Methylmercury ; Mice ; Golgi methods ; Electron microscopy ; Dendrites ; Purkinje cells ; Perivascular glia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neonatal C57BL/6J mice were injected with 5 mg/kg body weight of203Hg-labeled methylmercuric chloride on postnatal days 3, 4, and 5, totaling 15 mg/kg body weight per animal. The experimental and control animals were sacrificed on postnatal day 15. Whole body radioactivity of203Hg progressively increased during the 3-day injection period and reached the peak level and remained at peak levels until the time of sacrifice. This indicates a lack of clearance of203Hg by neonatal mice during the period examined in this study. Golgi preparations of cerebella of MeHg-treated animals revealed significant reduction in dendritic arborization of Purkinje cells. Ultrastructurally, the vascular endothelium showed attenuation with increased electron density and frequent vacuolization of cytoplasm. Marked swelling of perivascular glia was noted in most of the capillaries throughout the cerebella of MeHg-treated animals.
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 55 (1981), S. 77-80 
    ISSN: 1432-0533
    Keywords: Esthesioneuroepithelioma ; Olfactory neuroblastoma ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A rare case of esthesioneuroepithelioma infiltrating the right frontal lobe is reported in a 41-year-old man. This tumor composed of compact lobules with tubular arrangements, ultrastructurally showed two different cell types, both devoid of neurosecretory granules and reminiscent of neurons and sustentacular cells of the olfactory epithelium. These features are distinguished from those generally observed in olfactory neuroblastomas.
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 55 (1981), S. 89-95 
    ISSN: 1432-0533
    Keywords: Electron microscopy ; Morphometry ; Sorbitol pathway ; Diabetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Galactose neuropathy is characterized by progressive endoneurial edema manifested by a gradual increase in endoneurial fluid pressure. Edema accumulates via a unique mechanism of osmotic force generated by products of the polyol pathway, synthesized within the endoneurial compartment. This paper presents morphologic findings showing firstly, that blood nerve barrier permeability to horseradish peroxidase complexes appears unchanged and secondly, peripheral nerve edema in this condition is restricted to extraganglionic endoneurium sparing the spinal ganglia and adjacent roots. Thirdly, mast cells accumulated in significant numbers and electron microscopy revealed degranulation. There was no evidence of edema in Schwann cell cytoplasm, the putative site of galactitol accumulation via the sorbitol pathway. These findings are discussed with respect to diabetic neuropathy for which galactose intoxication is a useful experimental model.
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  • 19
    ISSN: 1432-0533
    Keywords: Postischemic recirculation ; Complete cerebral ischemia ; Ischemic neuronal injury ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The neuronal response to complete cerebral ischemia (CCI) of 5–15 min duration was evaluated at the light and electron microscopic level subsequent to postischemic recirculation periods of up to 60 min. Following postischemic reperfusion, the homogeneous neuronal changes characteristic of permanent CCI were modified into a heterogeneous pattern of selectively vulnerable neuronal responses. Four basic types of neuronal injury were represented within this heterogeneous neuronal population. The Type I neuronal response was most numerous and consisted of chromatin clumping, nucleolar condensation and a breakdown of polysomes. This response may represent a reversal of some of the neuronal changes observed after permanent CCI. In addition to the above changes, Type II neurons contained swollen mitochondria and Golgi saccules which appeared as microvacuoles under the light microscope. Type III neurons displayed varying degrees of neuronal shrinkage and numerous swollen mitochondria. Type IV neurons were markedly shrunken and electron-dense with few identifiable subcellular structures. The distribution of Type I neurons was random but the other neuronal responses occurred in “selectively vulnerable” brain regions. The number of Type II, III, and IV neurons increased with extended insult durations but were unaffected by the length of recirculation. Ten minutes of CCI represented the threshold for a significant increase in the number of severely altered neurons. These findings suggest that considerable neuronal injury may be present after 10–15 min of CCI, and the lack of a recirculation period following CCI appears to afford the brain parenchyma an extensive degree of structural protection.
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 53 (1981), S. 65-74 
    ISSN: 1432-0533
    Keywords: Hexachlorophene ; Central nervous system ; Mice ; Baboons ; Electron microscopy ; Neurotoxicology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A study on hexachlorophene encephalopathy in mice and baboons is reported. By light microscopy, a severe spongiform lesion of the central nervous system (CNS) was localized in the white matter, without myelin breakdown or cellular reaction. By electron microscopy, the myelin alteration was characterized by wide intralamellar spaces or “splitting” developed in the intraperiod line of compact sheaths. The acute changes described were induced by administration of the drug by the digestive or cutancous routes at various dosage levels in an aqueous solution or in talcum powder. The toxic effects depended on the age of the animals, the survival times and the concentrations of hexachlorophene, i.e., 6%, 3%, and 0.5%. The findings are compared with previous reports on the neurotoxicity of hexachlorophene and other chemicals in humans and experimental animals. Hexachlorophene cannot be recommended for use in young infants because of its neurotoxicity in very low doses as demonstrated in the present report.
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  • 21
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 53 (1981), S. 165-168 
    ISSN: 1432-0533
    Keywords: Lewy body ; Neurofibrillary tangle ; Locus ceruleus ; Aged brain ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The presence of Lewy body and neurofibrillary tangle in the locus ceruleus neurons of aged brain is described. Ultrastructural study revealed that in some Lewy bodies the presence of “twisted tubules” or “paired helical filaments” amongst the filaments of the Lewy body. A quantitative analysis of serial sections of locus ceruleus from aged brain, incidences of the Lewy body and neurofibrillary change were 0.07% (9/11,515) and 6.6% (15/11,515), respectively. The incidence of neurons containing both structures was 0.008% (1/11,515).
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  • 22
    Electronic Resource
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    Springer
    Acta neuropathologica 54 (1981), S. 43-53 
    ISSN: 1432-0533
    Keywords: Uremia ; Kidney transplantation ; Polyneuropathy ; Light microscopy ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Eighteen patients, ten with clinical uremia and eight with functioning kidney transplants, were studied clinically for neuropathy and were subsequently subjected to a sural nerve biopsy. The biopsy specimens were studied using light and electron microscopic and morphometric methods. The clinical polyneuropathy was qualitatively and quantitatively most severe in the hemodialysis group. These results conformed with the light and electron microscopic observations. Clinical, morphological and morphometric indications of recovery from uremic neuropathy were observed in the transplant recipients. The pathophysiology of uremic peripheral neuropathy was marked axonal degeneration. Pathologic Schwann cells were also frequently found. Axonal degeneration and Schwann cell damage seemed to exist independently of each other. In morphometric analysis, axonal atrophy and abnormal myelin sheath thickness were observed in all patient groups. A close relationship was found between axonal atrophy and low conduction velocity. Unexpectedly low nerve conduction velocities were also observed, which cannot be explained by either loss of nerve fibers or demyelination. The findings of damaged endoneural blood capillaries supported the ischemic theory as one mechanism in the pathogenesis of uremic neuropathy.
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  • 23
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    Anatomy and embryology 161 (1981), S. 433-451 
    ISSN: 1432-0568
    Keywords: Rhombencephalon, rat ; Subependymal cysts ; Morphogenesis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A bilaterally symmetrical cystic cavity is situated in the subependymal neuropil of the rostral rhombencephalon of the rat during the perinatal period of ontogeny. These cysts are formed by the confluence of enlarged extracellular spaces in this region between E18 and E20. The cysts are present for about 2 weeks but disappear on about P15 without trace. They have a maximal volume of about 0.004 to 0.006 mm3 on P2, with a rostrocaudal extension of about 200 μm. Their shape is characterized by a medial convexity and a lateral concavity, and they have their maximal circumference at about the middle of the rostrocaudal axis. The caudal portion is juxtaposed to the subependyma, while the rostral part lies in the neuropil of the presumptive griseum centrale pontis. In the lumen and the wall of the cysts are found numerous macrophages, hlioblasts and some degenerating axons and dendrites. The significance of these cysts in the context of morphogenesis and the origin of the numerous macrophages within them are both unresolved.
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  • 24
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    Acta neuropathologica 53 (1981), S. 237-248 
    ISSN: 1432-0533
    Keywords: Thyroxine effect on muscle ; Histochemistry ; Immunopathology ; Electron microscopy ; Diagnostic muscle pathology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Proximal myopathy and different types of neuromuscular syndromes are frequently observed in hyperthyroid patients with complicated thyrotoxicosis. Conflicting reports on the changes seen in muscle biopsies range from no abnormalities to muscle necrosis with the fibers being replaced by connective tissue and fat. On the basis of 21 skeletal muscle biopsies from chronic thyrotoxic myopathic patients, coupled with studies in experimentally induced triiodothyronine myopathy in rats, the histological, histochemical, immunofluorescent, and electron-microscopic findings diagnostic for thyrotoxic myopathy are defined. These criteria include: clumping of nuclei, los of cross-striation, vacuolar degeneration, and fatty infiltration of endo- and perimysium, presence of giant mitochondria, increased number of mitochondria, disorganization of contractile elements, swelling of transverse tubules, presence of microtubular aggregations, and a significant increase of lipofuscin granules. Both muscle fiber types or in some cases selective type II fibers display atrophy with signs of reinnervation. These alterations are polyfocal and polyphasic and, therefore, polychronous and stereotyped rather than pathognomonic. However, they are related to the severity of thyrotoxic myopathy and the duration of disease. The results of muscle biopsies have a predictive value in determining the reversibility or irreversibility of pathologic changes with therapeutic consequences.
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  • 25
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    Acta neuropathologica 55 (1981), S. 143-149 
    ISSN: 1432-0533
    Keywords: Pineal parenchymal neoplasm ; Electron microscopy ; Primitive neuroectodermal cell ; Dense core vesicles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fine structure of two pineal parenchymal neoplasms has been described. The tumors contained a predominance of small, poorly differentiated cells with prominent nuclei and scanty cytoplasm. These cells were similar to those found in medulloblastomas, primitive cerebral neuroectodermal tumors, and fetal cerebellum and cerebrum. Some cells contained 9+0 cilia, dense core vesicles, and processes containing microtubules and numerous dense core and clear vesicles, suggesting neuronal differentiation. Astrocytic elements were also present. This study suggests that the predominant cells of these tumors are primitive neuroectodermal elements which have the potential to differentiate along several different lines.
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  • 26
    ISSN: 1432-0533
    Keywords: Immunochemistry ; Pituitary adenoma ; Electron microscopy ; Mixed eosinophilic-cromophobe ; Gonadotropin ; Thyrotropin-secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twenty-nine pituitary adenomas were studied by histologic, electron-microscopic, and immunohistochemical techniques. By conventional histological stains, 19 cases were considered chromophobe, five cosinophilic, and five mixed chromophobe and eosinophilic adenomas. Immunohistochemistry, with specific antibodies against human GH, PRL, FSHβ, LHβ, and TSHβ showed, clearly, secreting and non-secreting groups of tumors: growth hormone-secreting adenomas (four cases), prolactin-secreting adenomas (eight cases), thyrotropin and/or gonadotropin-producing tumors (seven cases), and non-secreting adenomas (ten cases). Electron microscopy showed secretory granules of varying numbers, sizes, and shapes in all tumor cells in all 29 cases. The endoplasmic reticulum appeared markedly increased in 5/8 of the prolactin producing tumors; mitochondria also appeared markedly increased in 3/7 of the thyrotropin-gonadotropin group. These three cases could be considered “oncocytomas” by electron-microscopic criteria. Patients with prolactin-secreting adenomas had high serum prolactin and typical clinical symptoms associated with such tumors. One patient with large numbers of TSH-containing cells in her tumor and some cells with growth hormone and FSH had overt thyrotoxicosis. Although the remaining six tumors stained specifically for one hormone or another, no clinical correlation was possible. Conventional electron microscopy has some value in the generic identification of puritary tumor cells, but no value in the recognition of specific secretory products or specific cell types. Conventional histopathology is the least reliable method to correctly identify a specific type of pituitary adenoma, beyond the identification of the adenomatous changes. This study demonstrates the existence of gonadotropin- and/or thyrotropin-secreting pituitary adenomas, among so-called chromophobe adenomas, or “undifferentiated adenomas”.
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  • 27
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    Acta neuropathologica 55 (1981), S. 307-318 
    ISSN: 1432-0533
    Keywords: Diphtheritic polyneuropathy ; Muscle biopsy ; Intramuscular nerves ; Electron microscopy ; Histochemistry ; Diphtherie-Polyneuropathie ; Muskelbiopsie ; intramuskuläre Nerven ; Elektronenmikroskopie ; Histochemie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Biopsien aus Extremitätenmuskeln von vier Kranken mit schwerer tetraplegischer Form der Diphtherie-Polyneuropathie konnten nahe dem Höhepunkt der Erkrankung gewonnen und mit modernen Methoden einschließlich Histochemie, Elektronenmikroskopie und morphometrischer Verfahren untersucht werden. Vergleichbare Studien wurden bisher nicht veröffentlicht. Die Muskulatur bot vorwiegend neurogene Veränderungen mit disseminierten angulierten Fasern, eine besonders die Typ-2B-Fasern betreffende, mehr generaliierte Atrophie sowie Targetoidherde oder „Cores” in Typ-1-Fasern. Darüber hinaus fanden sich eindeutige myogene Veränderungen mit unterschiedlichen Degenerationsphänomenen bis zur totalen Nekrose, offenbar — wie am Herzmuskel —toxischer Herkunft. Das neurogen-myogene Mischbild entsprach den elektromyographischen Befunden. Die intramuskulären Gefäße waren unauffällig bis auf vereinzelte perivaskuläre, vorwiegend mononukleäre Zellinfiltrate mit reichlich zerebriformen lymphoiden Zellen, wahrscheinlich T-Lymphozyten. An 11 intramuskulären Nerven und zwei motorischen Endplatten waren eindeutig auf die Diphtherie zu beziehende Veränderungen nicht aufzudecken. Dies kann als Hinweis auf eine vorwiegend proximale Entmarkung bei der Diphtherie-Polyneuropathie des Menschen gedeutet werden, die damit eher der experimentellen Form des Kaninchens als der des Meerschweinchens entspricht.
    Notes: Summary Mucle biopsies from the lower extremities of four patients with severe tetraplegic form of diphtheritic polyneuropathy were examined by modern techniques including histochemistry, electron microscopy and morphometric procedures. Until now comparable studies have not been published. The biopsies were removed during the acute stage of the polyneuropathy. We found scattered small angulated muscle fibers beside a more generalized slight atrophy predominantly of type 2B fibers and targetoid-phenomenons or cores in type 1 fibers. Beside this neurogenic pattern there also were, corresponding with the results of electromyography, primary myogenic alterations with different degenerative phenomenons, suspicious of toxic origin as in cardiac muscle. The intramuscular vessels showed no abnormalities except some perivascular predominantly mononuclear cellular reactions with a remarkable number of cerebriform lymphoid cells, probably T-lymphocytes. No specific pathological alterations could be detected in 11 intramuscular nerves and two motor endplates. This may reflect the more proximal demyelination of human peripheral neurons by the diphtheria toxin as found in experimental diphtheria of the rabbit in contrast to the more distal type of the guinea pig.
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  • 28
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    Acta neuropathologica 54 (1981), S. 287-292 
    ISSN: 1432-0533
    Keywords: Mucopolysaccharidoses III ; Sanfilippo's syndrome ; Histochemistry ; Electron microscopy ; Lipofuscin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A histochemical and ultrastructural study was made on the brain of a 23-year-old man with Sanfilippo's syndrome. In accordance with previous reports the cortical nerve cells contained a PAS-positive lipid storage substance. This showed intense autofluorescence in UV-light and was positive with various stains for lipofuscin. The storage material appeared ultrastructurally as inclusion bodies composed of short lamellated membranes, granular material, and vacuoles. In addition, concentrically and transversely lamellated membranous cytoplasmic bodies were observed in the nerve cells. It is concluded that the PAS-positive lipid storage material in the neurons was composed partly of lipofuscin in addition to other lipids presumably glycosphingolipids.
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  • 29
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    Acta neuropathologica 55 (1981), S. 81-87 
    ISSN: 1432-0533
    Keywords: Canine CNS ; Myelination ; Hypomyelinogenesis ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of myelin deficiency in Chow Chow dogs was studied in the spinal cord of a 15-month-old and a 3-year-old animal. It was found that myelination progresses with age in these dogs but is still deficient at the age of 3 years. The findings included axons with thin or uncompacted myelin sheaths, separated from each other by massive astrocytosis, and bizarre myelin formations. Normal numbers of morphologically normal oligodendrocytes were present in the myelin-deficient areas. The disease in these Chow Chow dogs consists of a strongly retarded myelination which is possibly due to a dysfunction or delay in glial maturation.
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  • 30
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    Archives of dermatological research 271 (1981), S. 171-182 
    ISSN: 1432-069X
    Keywords: Hypomelanotic macule ; Tuberous sclerosis ; Electron microscopy ; Hypomelanotische Macula ; tuberöse Hinrsklerose ; Elektronenmikroskopie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Hypomelanotische Maculae der Haut bei der tuberösen Hirnsklerose (TS) werden verursacht durch einen komplizierten Prozeß, in den die Synthese und Reifung von Melanosomen verwickelt sind. Weil die Charakterisierung von Hautbiopsien aus hypomelanotischen Maculae bei TS-Patienten zur Zeit nicht ausreichend ist, haben wir eine quantitative Methode entwickelt, durch die die Reifung der Melanosomen in den Melanocyten erforscht wird. Diese Methode wurde anhand von Biopsien aus hypomelanotischer und der angrenzenden Haut von sechs Patienten mit erwiesener TS geprüft und mit bekannten Methoden verglichen. Bei allen sechs Patienten wurde in der hypomelanotischen Macula eine statistisch signifikant niedrigere Zahl von pigmentierten Melanosomen pro melanocytärem Perikaryon und dendritischem Zellprozeß festgestellt als in der angrenzenden Haut. Die relative Anzahl von Stadium III- und IV-Melanosomen hatte in der hypomelanotischen Macula abgenommen, die von Stadium II-Melanosomen zugenommen (auch statistisch signifikant). Durch Verwendung unserer Methode kann die Hypomelanose der TS zuverlässig charakterisiert werden, was möglicherweise aus diagnostischer Sicht wichtig ist. Die Resultate der Melanosomengrößenmessung oder die des DOPA-Verfahrens dagegen waren statistisch nicht signifikant.
    Notes: Summary Hypomelanotic macules of the skin in tuberous sclerosis (TS) are caused by a complex process, involving the synthesis and maturation of melanosomes. A quantitative method was developed to investigate the maturation of the melanosomes at the level of the melanocytes. The method was tested on biopsies of hypomelanotic and adjacent normomelanotic skin from six patients with definite TS, and compared with other methods. In all patients, a statistically significant lower number of pigmented melanosomes was found per cross-sectioned melanocytic perikaryon and dendritic cell process in the hypomelanotic as compared to the normomelanotic skin. The relative numbers of stage III and IV melanosomes were decreased, and of stage II melanosomes increased in the hypomelanotic macule (also statistically significant). This indicates that it is possible to characterize the hypomelanosis in TS reliably, which may have diagnostic importance. In our hands, assessment of the size of the melanosomes did not show a statistically significant difference between hypo- and normomelanotic skin; the difference found with the DOPA technique was more evident, although not statistically significant.
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  • 31
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    Calcified tissue international 33 (1981), S. 143-151 
    ISSN: 1432-0827
    Keywords: Calcium transport ; Cytochalasin B ; Dihydrocytochalasin B ; Colchicine ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary In vivo calcium absorption was studied in normal and rachitic chicks. Cytochalasin B (CB) at a concentration of 25 µg/ml added to the medium inside the duodenal lumen inhibited calcium absorption (20 min) from 82.5±1.9% of calcium absorbed in the controls to 59.2±3% in normal and from 70.0±2.3% to 47.0±2.1% in rachitic chicks. In vitro studies by everted ileal sacs of young rabbits also showed an inhibition of active transport of calcium due to CB. Whereas in the controls the ratio of45Ca concentrations in serosal and mucosal media (60 min) was 7.2±0.32, the ratios were 5.24±0.52; 4.40±0.36; 3.40±0.42; 5.77±0.52; 1.38±0.08; and 1.06±0.02 in the presence of CB at concentrations of 5, 10 and 25 µg/ml; colchicine 10−4M, Na citrate 0.02M, and heat-devitalized conditions, respectively.45Ca concentration in the mucosal scrapings was also affected. It showed an increase from controls (15,101±404 cpm/mg) and correlated with CB concentration: 17,378±489, 19,015±1000, and 20,201±362 at 5, 10, and 25 µg/ml, respectively. Dihydrocytochalasin B also inhibited active calcium transport and caused an increase in45Ca concentration in the mucosal scrapings. Correlated electron microscopic studies showed certain changes in the brush border, especially in some actin microfilaments in the terminal web region. It seems that these morphological alterations may be related to transcytoplasmic movement of calcium.
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  • 32
    ISSN: 1432-0827
    Keywords: Alcohol ; Electron microscopy ; Growth plate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We have previously demonstrated that ethanol has a direct toxic effect on the rat skeleton characterized by decreased trabecular bone volume. In the present study, we examined the ultrastructure of the distal radial epiphyseal growth plates in these same animals. Eight weeks of ethanol administration to 12 male rats results in serum alcohol levels of 140 mg/dl but did not alter the width or light microscopic appearance of the radial growth plate. Quantitative electron microscopy failed to demonstrate morphologic evidence of toxicity in the skeletal cells. We conclude that although ethanol appears to have a direct effect on rat bone characterized by enhanced resorption, toxicity is not attended by ultrastructural changes in the skeletal cells.
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  • 33
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    Calcified tissue international 33 (1981), S. 529-540 
    ISSN: 1432-0827
    Keywords: Bone cells ; Electron microscopy ; PTH ; PGE1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Four different cell populations—designated PF, OB, OC, and PC—were isolated from calvaria of 18-day-old chick embryos for analysis of the effects of hormones on bone tissue. The cell populations were studied with histological and biochemical methods. Apart from the well-known cell types present in calvaria, a new cell type was found in the noncalcified organic matrix between the osteoblastic layer and the calcified matrix. These cells were provisionally called osteocytic osteoblasts. They represent the “transition state” between osteoblasts and osteocytes. On the basis of histological studies with light microscopy (LM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), the PF population was considered to originate primarily from the periosteal fibroblasts, the OB population from the osteoblasts and osteocytic osteoblasts. The population of cells still present in calvaria after removal of periosteal fibroblasts and osteoblasts was called the OC population. This cell population was very much enriched with osteocytes. The fourth isolated population (PC) was a mixed population of fibroblasts, osteoblasts, and preosteoblasts. On exposure to parathyroid hormone (PTH), all four cell populations showed increased lactate production, but only the OB and OC populations displayed increased cAMP production. Prostaglandin E1 (PGE1) stimulated cAMP production in both OB and PF cells. From the results of this study it was concluded that PTH receptors are present on all of the cell types studied, but that occupancy of the receptor induces adenylate cyclase stimulation only in osteocytes and fully differentiated osteoblasts.
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  • 34
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    Calcified tissue international 33 (1981), S. 119-124 
    ISSN: 1432-0827
    Keywords: Avian eggshell ; Microstructure ; Electron microscopy ; Electron diffraction ; Calcite growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The eggshell of the domestic fowl has been studied by transmission electron microscopy and diffraction. Thin sections of shell were prepared by chemical and ion-beam thinning techniques. Each calcite column of the palisade layer consisted of crystallites of diameter 20 to 30 µm with some tendency for crystallite alignment within a single column. Evidence indicates that there was no significant preferred orientation in the palisade layer as a whole. Only in the surface layer was any preferred orientation detected, and here {1014} planes tended to lie parallel to the surface. The results are compared with previously published data, and calcite nucleation and growth are discussed.
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  • 35
    ISSN: 1432-1246
    Keywords: Diesel exhaust emission ; Liver ; Electron microscopy ; Freeze-fracture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The livers of Syrian golden hamsters were examined with the light and electron microscope using the techniques of thin sectioning and freeze-fracture following 5 months of exposure to various concentrations of diluted diesel exhaust gases. The light microscopical examination showed enlarged sinusoides with activated Kupffer's cells and slight changes in the cell nuclei. In the electron microscopical examination the most striking changes were seen in the mitochondria, which frequently showed a loss in cristae. In addition, the mitochondria exhibited pleomorphic character. The microbodies were of the same size as mitochondria. An increase in the number of lysosomes was observed especially in the tissue surrounding the narrow bile canaliculi. The various alterations corresponding to the different concentrations of exhaust gases could be seen especially well in the sinusoides, the mitochondria and the microbodies. In general the hepatocytes appeared to be moderately enlarged. The zonulae occludentes showed a more irregular outline and large maculae tight junctions were found on the lateral region of the plasmalemma of hepatocytes. The gap junctions exhibited a wide range of structural diversity. The intramembranous particles on the P fracture face of the plasmalemma of hepatocytes are aggregated.
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  • 36
    ISSN: 1432-1106
    Keywords: Cat-spinocervical tract cells ; Intracellular staining ; Electron microscopy ; Synaptic vesicles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Synaptic vesicles in initial collateral terminals of two feline Spinocervical tract cells have been investigated after intracellular staining with horseradish peroxidase. A total of 5325 vesicles in 52 axodendritic and 26 axo-somatic terminals were analysed after aldehyde-osmium fixation. The greatest length and longest perpendicular width of each vesicle were measured, and the ratio and geometric mean of the diameters (gm-diameters) were calculated. The vesicles were divided into classes with round, elliptical and flat organelles. The variations in vesicle length, gm-diameter, and diameter ratio were statistically analysed by means of one- and two-way analyses of variance and t-tests. The diameter ratio, the length of round vesicles, and the gm-diameters of round and elliptical vesicles differed significantly between the cells. The length and gm-diameter of the elliptical vesicles differed significantly between the groups of axo-dendritic and axo-somatic terminals of each cell. Round vesicles were significantly longer in the axosomatic than in the axo-dendritic terminals of each cell, and the gm-diameter showed this relation for both round and elliptical vesicles. It is assumed that a one-size vesicle could not account for all the measured profiles. The variability of synaptic vesicles within and between the functionally similar cells emphasize the difficulties in using the morphology of synaptic vesicles for a discrimination of axon terminals of different origin.
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  • 37
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    European biophysics journal 7 (1981), S. 209-212 
    ISSN: 1432-1017
    Keywords: Photosynthetic bacteria ; Electron microscopy ; Planar lattices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The thylakoids of Rhodopseudomonas viridis have been studied by freeze-fracturing whole cells. Depending on growth conditions and treatment before freezing, three different types of particle arrangements in the photosynthetic membrane are reported: a random arrangement, an isometric (quadratic) lattice arrangement with a lattice constant of 12.5 ± 0.8 nm, and a hexagonal lattice arrangement with a lattice constant of 12.5 ± 0.8 nm.
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  • 38
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    Archives of toxicology 47 (1981), S. 101-111 
    ISSN: 1432-0738
    Keywords: Cerebellar cortex ; Methylmercury ; Toxicity ; Rat ; Morphometry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A single dose of 10 mg methylmercury chloride per kg body weight was given to 30 days old rats and to adult rats (180–200 g). This resulted in brain levels of 1.4–2.2 μg Hg/g wet weight. In the young rats electron microscopic morphometry showed swelling of the granule cells. The extent of changes was more pronounced in the cerebellar hemispheres than in the vermais and flocculus. At 7 days after giving the methylmercury the granule cells appeared to have returned to normal. Methylmercury produced both light and electron microscopic changes in cerebellar neurons of adult (180–200 g) rats 3 days after dosing. 2.5–10% of the granule cells appeared dark and condensed in toluidine blue stained semithin sections of perfusion fixed and plastic embedded material. In control animals the comparable percentage never exceeded 1. By electron microscopic morphometry the dark cells proved to be shrunken to 70%, whereas the remaining light granule cells were swollen to 130% of the normal cell volume. The heterochromatin and mitochondrial volumes per cell remained constant in both dark and light cells from methylmercury treated animals. In the Purkinje cells from both young and adult rats, geometrical changes in the cisternae of the granulated endoplasmic reticulum were evident. The swelling and shrinkage of the granule cells is supposed to be due to impaired electrolyte control and the disorganized granulated endoplasmic reticulum of the Purkinje cells may be related to the deleterious effects on protein synthesis.
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  • 39
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    Journal of neurology 225 (1981), S. 67-72 
    ISSN: 1432-1459
    Keywords: Ewing sarcoma ; Epidural tumors ; Spinal cord compression ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wird ein Ewing-Sarcom, welches sich außerhalb des Skelettes bei einem Kind entwickelte, geschildert. Klinisch manifestierte es sich als epidurale Masse. Bei der chirurgischen Exploration zeigte sich ein brüchiges Gewebe, welches 2–3 cm lang war und nicht vom Knochen ausging. Lichtmikroskopisch und elektronenmikroskopisch ließ sich die Diagnose eines Ewing-Sarcoms stellen. Es werden morphologische Aspekte und differentialdiagnostische Überlegungen in Zusammenhang mit Tumoren des Epiduralraumes diskutiert.
    Notes: Summary The clinicopathological findings in a child with extraskeletal Ewing sarcoma are described. The patient complained of pain in the lower back and difficulty walking. An extraskeletal, epidural, friable tumor, 2–3 cm long was removed from the epidural space. It had no relationship with the bone structures. Light and electron microscopic examination of the tumor led to the diagnosis of Ewing sarcoma. The morphological aspects of this neoplasia and the problem of the differential diagnosis with other small cell tumors of the epidural space are discussed.
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  • 40
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    Journal of neurology 224 (1981), S. 171-182 
    ISSN: 1432-1459
    Keywords: Cerebral amyloidoma ; Congo red birefringence ; IgM immunofluorescence ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Eine fast walnußgroße, intra- und subcortical gelegene Masse von Congo-Rot-färbbarem Amyloid mit einigen umgebenden Lympho-Monozyten, Plasmazellen und mehrkernigen Elementen sowie doppelbrechenden plumpen Plaques und fein dispers verteilten Amyloidpräzipitaten innerhalb eines unmittelbar angrenzenden kleinen Rinden-Restgewebes wurde operativ aus dem Occipitallappen entfernt. Aufgrund der typischen grüngelblichen Doppelbrechung im Congo-Rot-Präparat, der Thioflavin-Fluoreszenz, der positiven PAS-Reaktion, Bindegewebsfaserfärbungen und des elektronenmikroskopischen Nachweises charakteristischer unverzweigter 10 nm-Fibrillen kann die Diagnose eines cerebralen Amyloidtumors (Amyloidom) gestellt werden. Bei nur schwacher Anfärbung des vielfach deutlich appositionell gewachsenen Substrates mit Anti-Bence-Jones-Proteinserum (λ-Kette) reagierten die Perikarya der mononukleären lymphoiden Zellen und der Plasmocyten im indirekten Immunfluoreszenztest besonders mit Anti-IgM (FITC-markiert). — Die Trägerin, eine 46jährige Hausfrau, hatte jahrelang recidivierende depressive Episoden und in den letzten 4 Jahren fortschreitende neurologische Symptome nach Art eines chronischen raumfordernden Prozesses ohne jegliche Anzeichen einer Systemerkrankung oder Gammopathie. Sie erholte sich nach der Operation ziemlich gut. Es wird angenommen, daß es sich — analog zum tumorförmigen Amyloid in Haut, Lunge oder anderen Organen — hier um eine isolierte cerebrale Form von Paramyloid oder nodulärer primärer Amyloidose (Amyloid L) im Sinne von Reimann et al. (1935), Cohen (1967), Azar (1973), Langer und Missmahl (1980), Glenner (1980) u. a. handelt.
    Notes: Summary An almost walnut-sized tumor was removed surgically from the left occipital lobe of a 46-year-old woman, who had suffered for 4 years from progressive visual loss with scotoma and finally from hemianopia, associated with attacks of headaches and recurrent episodes of depression each lasting for some weeks or months. Neuropathological examination, including polarization, thioflavine fluorescence, immunofluorescence staining, and electron microscopy, revealed an amyloidoma, which consisted of broad appositionally grown amyloid deposits surrounded by some plasma cells, monocytic or foreign body cell types. The massive accumulations, often associated not only with blood vessels or perivascular collagenous fibers but also lying in the cerebral tissue not unlike senile plaques in the cortical gray matter, corresponded to gradually growing masses as seen in the repeated CT scans. This unique lesion in the brain of a patient who did not show any evidence of systemic disorder, seems to confirm that the spontaneous tumor-like amyloid, which gave an immunofluorescent staining mainly with anti-IgM, is a special variant of primary amyloidosis (amyloid L) or of so-called paramyloid (Reimann et al. 1935; Cohen 1967; Azar 1973; Langer and Missmahl 1980).
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  • 41
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    Archives of microbiology 130 (1981), S. 125-128 
    ISSN: 1432-072X
    Keywords: Rhodospirillum rubrum ; Chromatophores ; Reaction centers ; Liposomes ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In freeze-fractures of chromatophores of Rhodospirillum rubrum the reaction centers are seen as hexagonal arranged particles of 13 nm diameter with a density of around 5,500 particles per μm2. Similar regions on the cytoplasmic membrane suggest that these parts are the prospective invagination sites. Isolated reaction centers are easily incorporated into liposomes. In freeze fractures of liposomes particles similar in shape and size, although less dense as in chromatophores are observed. In negative staining much smaller units of only 5 nm in diameter are found indicating that reaction centers occur in the membrane as tri- or tetramers. There is a strong correlation between particle density in chromatophores and titratable reaction centers remaining in these membranes after extraction of reaction centers by detergents; both values are in good agreement with the yield of reaction centers at a given detergent concentration.
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  • 42
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    Archives of microbiology 129 (1981), S. 129-134 
    ISSN: 1432-072X
    Keywords: Cockroach ; Hindgut ; Distribution ; Microbial morphotypes ; Transmission ; Electron microscopy ; Statistical analysis ; Eublaberus posticus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relative numbers of fourteen microbial morphotypes in transmission electron micrographs of the hindgut of a cockroach, Eublaberus posticus, were counted and their distribution was analyzed statistically. The microbiota of three wall-associated regions (the anterior paunch, the posterior paunch, and the black band region) was clearly different from that of the gut lumen. The three wall fractions were also significantly different from each other. Only one of the fourteen types, prosthecate bacteria, appeared to be distributed randomly in the four fractions. The five main wall-associated morphotypes individually constituted up to 41% of the microbes in some micrographs. They included one type with the characteristic morphology of Methanospirillum. Six morphotypes rarely made up over 2% of the population, but were consistently present. The numbers of the remaining three morphotypes were quite variable between micrographs and between individual insects, but when present often made up 5–10% of the population.
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  • 43
    ISSN: 1432-072X
    Keywords: Biological control ; Cyanobacteria ; Electron microscopy ; Entrapment ; lysis ; Myxococcus ; Phormidium ; Spherule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A Myxococcus xanthus isolate from a farm drainage ditch, designated strain PCO2, is capable of rapidly inducing lysis of both agar and liquid-grown cultures of the cyanobacterium, Phormidium luridum, var. olivacea. Microscopic studies of the predator-prey interaction demonstrate that lysis of the cyanobacterium occurs within clumps and spherules formed by the cells of M. xanthus PCO2. In the earliest stage, one sees the formation of irregular microclumps of bacteria and cyanobacterial filaments. As these clumps mature, colonies 1 to 6 mm in diameter develops. The center of these densely green colonies contains cyanohacteria in various stages of degradation, while the periphery is almost exclusively a tightly woven mass of myxobacterial cells. Electron microscopy shows that long extrusions from the outer membrane of the M. xanthus PCO2 cells are involved in the formation both of initial clumps and of mature colonial spherules. These extrusions appear to efficiently entangle the cyanobacterial filaments in the culture environment. Predator-to-prey ratios of 1/10, 1/100 and 1/1,000 have resulted in cyanobacterial lysis. Because the entrapment and lysis of P. luridum filaments by M. xanthus PCO2 appears to be independent of any other heterotrophic nutritional requirement, as well as of environmental agitation, this system has potential as a biological control technique for undesirable aquatic cyanobacteria.
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  • 44
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    Archives of microbiology 130 (1981), S. 339-343 
    ISSN: 1432-072X
    Keywords: Leptospira ; Halophilic ; Electron microscopy ; X-ray analysis ; Inclusions ; Cytoplasmic tubules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The morphology of cells of strain Muggia, a slightly halophilic leptospire, was examined by the negative staining technique. The ultrastructure of the cells was rather similar to that of cells of Leptonema illini, i. e. the cells possessed cytoplasmic tubules. The basal complex of their flagella, however, was similar to the corresponding part of flagella on Gramnegative bacteria. The interior of the cells was densely packed with inclusions, except for the two outermost wavelengths at each end where these inclusions were absent. X-ray microanalysis showed that the inclusions contained sodium and chlorine as their main constituents. The inclusions disappeared upon storage of the cultures at room temperature.
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  • 45
    ISSN: 1432-072X
    Keywords: Ribulose bisphosphate carboxylase ; Quaternary structure ; Molecular weight ; Electron microscopy ; Cyanobacteria ; Synechococcus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ribulose bisphosphate (RuP2) carboxylase from the marme cyanobacterium, Synechococcus sp., comprised both large (57,000 dalton) and small (12,000 dalton) subunits. The undissociated, purified enzyme was considerably smaller than the spinach enzyme when compared by pore-gradient electrophoresis, gel filtration and density-gradient centrifugation. This suggested that the cyanobacterial enzyme might have a hexameric (L6S6) subunit structure, unlike the enzymes from spinach and many other organisms which are octamers (L8S8). However, the molecular weight of the Synechococcus enzyme was measured by equilibrium sedimentation and found to be 530,000, which is within the range observed for L8S8-type enzymes. Furthermore, electron microscopic studies of negatively stained preparations of both the native enzyme, and a preparation depleted of 87% of its small subunits by repeated mild-acid precipitation, revealed four-fold symmetry characteristic of an octameric, cubical structure. Synechococcus RuP2 carboxylase therefore must be an L8S8 octamer and its anomalous pore-penetration behaviour may be due to an asymmetric shape. Some support for the latter possibility was provided by electron miscoscopic observations of two different types of images which may be different views of the molecule in two planes.
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  • 46
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    Journal of cancer research and clinical oncology 100 (1981), S. 51-58 
    ISSN: 1432-1335
    Keywords: Electron microscopy ; Rat astrocytomas ; Dibutyryl cyclic AMP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two cloned rat astrocytoma cell lines, 36 B-10 and 40 A-2, maintained in vitro were treated with 1 mM dibutyryl cyclic AMP. This treatment induced arborization of cellular processes and rounding-up of cell bodies in both cell lines and was associated with increased microvillous development in 40 A-2. There were no detectable concomitant changes in either (a) the quantity or organization of microtubules or 80–100 nm microfilaments, or (b) the intensity of glial fibrillary acidic protein indirect immunofluorescence staining.
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  • 47
    ISSN: 1432-5233
    Keywords: Electron microscopy ; Glibenclamide ; Glucose oxidation ; Insulin biosynthesis ; Insulin secretion ; Islets of Langerhans ; Mitochondria ; Morphometry ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to evaluate long-term effects of sulphonylureas on pancreatic islet structure and function, isolated mouse islets were maintained in tissue culture for one week at various glucose concentrations, and in the absence or presence of glibenclamide. When the islets were cultured at 3.3 or 5.5 mmol/1, but not at 16.7 mmol/1 glucose, it was found that the drug stimulated insulin secretion into the culture medium during the initial 3 days of culture. During the remainder of the culture period no such enhancement of secretion was demonstrated. Insulin release due to glibenclamide apparently resulted in rapid depletion of intracellular insulin stores. The finding of an enlarged B-cell Golgi apparatus in the drug-treated islets was probably associated with granule discharge. The failure of glibenclamide to promote insulin secretion during the whole culture period could reflect the adverse effects of the drug on islet insulin biosynthesis as indicated by short-term experiments performed after culture. Similar experiments showed that the impaired insulin biosynthesis could not be restored by withdrawal of the drug from the culture medium for 3 days. Furthermore, the capacity for insulin release in response to an acute glucose challenge at the end of the culture period, was abolished by culture in the presence of glibenclamide. The drug effects on insulin biosynthesis and intracellular insulin stores, which were most pronounced at 5.5 mmol/1 glucose, possibly resulted from changes in B-cell metabolism as suggested by the diminished islet glucose-oxidation rate. The spatial characteristics of islet mitochondria indicated that these changes might involve an adaptation to substrates other than glucose. In conclusion, our findings suggest that sulphonylureas have an insulinotropic effect, which is however transient. Indeed, it rather seems as if long-term exposure of islet B-cells to sulphonylureasin vitro were accompanied by functional deficiency.
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  • 48
    ISSN: 1432-2307
    Keywords: Electron microscopy ; Effect of various GAG on fibril formation in vitro ; Collagen structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Proteoglycans (PG) and glycosaminoglycans (GAG) bind to collagen, and thus influence fibril formation. Polysaccharides interfere with the aggregation of collagen molecules and affect pattern formation. The morphological structure of type I and type II collagen was studied after adding different GAG to collagen solutions in test tubes in vitro. Electron microscopical investigations suggest that sulfated GAG change the aggregation behaviour of collagen molecules. Thus, the cross-striation pattern is changed. This effect seems to be based on the degree of sulfatation and not on the molecular weight of the GAG. Furthermore, GAG appear to have a stabilizing influence on the in vitro fibril formation.
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  • 49
    ISSN: 1432-2307
    Keywords: Endocrine tumour ; Pancreas ; Argentaffin reaction ; Immunocytochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An endocrine pancreatic tumour that had not caused any endocrine symptoms was examined by histological, immunocytochemical and electron microscopic techniques. The majority of the tumour cells were argentaffin and contained secretory granules of the enterochromaffin cell type. Immunocytochemically a minority of tumour cells reacted to antisera against β-endorphin, met- and leu-enkephalin, gastrin, somatostatin and ACTH. The tumour was thus multihormonal, and appeared to be more closely related to the classic Carcinoid tumours of the mid-gut than to most pancreatic endocrine tumours.
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  • 50
    ISSN: 1432-0878
    Keywords: Pancreatic islets ; Adrenergic innervation ; Insulin secretion ; Chemical sympathectomy ; Adrenalectomy ; Fluorescence histochemistry ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Morphological changes in the adrenergic innervation of pancreatic islets after chemical sympathectomy by use of 6-hydroxydopamine and the influence of the sympatho-adrenal system on insulin secretion were investigated in the mouse and rat. Fluorescence histochemistry revealed a clear-cut reduction in the number of adrenergic nerve fibers in the pancreatic islets 2 days after administration of 6-hydroxydopamine; the reduction was more pronounced in the rat than in the mouse. In the rat, a partial regeneration was seen after 6 weeks. In the pancreas of the mouse, after administration of 6-hydroxydopamine, a severe damage of unmyelinated nerve fibers was revealed electron microscopically. However, no ultrastructural or immunohistochemical alterations could be demonstrated in the endocrine cells of the islets. 6-Hydroxydopamine induced a depression of basal plasma insulin concentrations in mice and an elevation in rats. Adrenalectomy depressed basal plasma insulin levels in mice. The α-adrenoceptor antagonist phentolamine enhanced insulin secretion in normal mice. The secretory response of insulin to phentolamine was diminished by chemical sympathectomy and almost abolished by adrenalectomy or the combination of chemical sympathectomy and adrenalectomy. Thus, the effect of phentolamine is probably mediated by liberated catecholamines. It is concluded that basal insulin secretion is partially regulated by the sympatho-adrenal system and that species differences exist in this respect. In addition, the results suggest that endogenous catecholamines have the ability to promote insulin secretion.
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  • 51
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    Cell & tissue research 216 (1981), S. 471-479 
    ISSN: 1432-0878
    Keywords: Ovulation ; Perfusion ; Graafian follicle (Rabbit) ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the present investigation the ultrastructure of isolated rabbit ovaries, perfused with different media for various time periods, was studied. The steroid hormone production by the perfused ovary was also determined. Perfusion with Medium 199 results in prominent interstitial ovarian oedema which increases with perfusion time. Even after the addition of 6–10 % Dextran T40, oedema appears in the interstitial tissue of the ovary. Perfusion solutions with osmotically active colloid particles of large molecular size (Dextran T70; average molecular weight 70,000 and bovine serum albumin), cause less distortion in the ovarian structure, and ultrastructurally the ovarian tissues appear essentially the same as in the control ovaries. The results indicate that the perfused rabbit ovary, under strictly controlled conditions, can be used as an experimental model for studies of various aspects of ovarian function, including follicular rupture.
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  • 52
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    Cell & tissue research 216 (1981), S. 205-214 
    ISSN: 1432-0878
    Keywords: Compound eyes ; Insects ; Crustaceans ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The basement membrane of the compound eye of four insect species and three crustacean species was investigated employing electron microscopy. The basement membrane consists of an extracellular (basal lamina) and a cellular portion, the latter being composed of the flattened terminal extensions of cone cells and accessory pigment cells in insects and distal pigment cells in crustaceans. Other cells can also contribute to the basement membrane. It is thus a complex structure in all well-developed compound eyes. The cellular contributions vary in different species and were found to correlate to specific taxonomic units.
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  • 53
    ISSN: 1432-0878
    Keywords: Gastrin ; CCK ; Median eminence ; Electron microscopy ; Xenopus laevis (Amphibia, Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary By use of an anti-gastrin serum and colloidal gold- or ferritin-labelled sheep anti-rabbit γ-globulins, nerve fibres and nerve terminals containing a gastrin-like substance were characterized at the ultrastructural level in the median eminence of Xenopus laevis. These immunoreactive fibres contain neurosecretory granules displaying medium to high electron density and a mean diameter of 75 nm. Labelling intensity varies from granule to granule. This is the first demonstration at the ultrastructural level of the precise location of a gastrin-like hormone in the median eminence of a vertebrate.
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  • 54
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    Cell & tissue research 217 (1981), S. 211-223 
    ISSN: 1432-0878
    Keywords: Pituitary gland ; Pars intermedia ; Electron microscopy ; Sheep
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Light microscopy of coronal sections of the sheep pars intermedia revealed a compact, incompletely lobulated V-shaped region about 15–20 cells thick, situated between the pars distalis and the pars nervosa. A prominent hypophysial cleft and follicles containing a colloid-like substance were seen. Using electron microscopy, five cell types could be distinguished: pars intermedia glandular cells, pars distalis-like glandular cells, interstitial cells, follicular cells and cleft lining cells. The polyhedral to pear-shaped pars intermedia glandular cells predominated. They contained dense-cored, membrane-bound granules near the Golgi complex, and larger, irregular vesicles with finely granular contents of varying electron density throughout the remaining cytoplasm; exocytotic release of granules was occasionally observed. Smaller numbers of cells resembling those seen in the pars distalis were scattered throughout the pars intermedia. Interstitial cells usually possessed elongated cytoplasmic processes which extended between the glandular cells, and were characterized by deeply indented nuclei, elaborate junctional complexes and an absence of cytoplasmic granules. Cells lining the follicles resembled the interstitial cells. The major cells bordering the hypophysial cleft were triangular in section and bore irregular microvilli on their free surface. The pars intermedia appeared to be less vascular than the remainder of the hypophysis and only occasional fenestrated capillaries were seen. Nerve profiles were rare.
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  • 55
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    Cell & tissue research 215 (1981), S. 643-649 
    ISSN: 1432-0878
    Keywords: T-lymphocytes ; Blast cells ; Autoradiography ; Electron microscopy ; Stereology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary As a companion to an earlier study, the morphometric attributes of stimulated (blast-derived) lymphocytes in mouse axillary lymph nodes have been established using stereological and autoradiographic methods. Blast transformation was induced in vivo with dinitrochlorobenzene (DNCB) and stimulated cells were labelled with tritiated thymidine. Random samples of cells were taken for light and electron microscopic morphometry. In comparison to the unstimulated lymphocyte, the stimulated cell increased in size and possessed a greater plasma membrane surface area. Increase in cell size was the result of increases in the volumes of all measured subcellular compartments both in the nucleus and the cytoplasm. Heterogeneity of the stimulated cell population precludes firm conclusions regarding the significance of all these ultrastructural changes, though alterations in cell surface are discussed in the context of known biochemical differences accompanying blastogenesis.
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  • 56
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    Cell & tissue research 216 (1981), S. 557-568 
    ISSN: 1432-0878
    Keywords: Electron microscopy ; Neuroglia ; Silver impregnation ; Brain ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The silver-impregnation procedure of Tsujiyama is suitable for demonstration of all three classical types of neuroglial cells; in the present study it was used for electron microscopic identification of neuroglial cells in the brain of the cat. The aim of the present study was 1) to determine impregnated structural correlates of neuroglial cells at the light- and electron-microscopic levels, and 2) to determine whether the method of Tsujiyama is applicable for the electron microscopic identification of the single types of neuroglial cells. Silver deposits were observed over the cytoplasm and processes of astrocytes where numerous glial filaments were present. Oligodendrocytes and microglial cells may be precisely differentiated by use of Tsujiyama's silver impregnation method at the electron microscopic level due to the pattern of silver-deposition in these two basic types of cells. This silver-impregnation method combined with electron microscopy is thus suitable for a precise identification of neuroglial cells; the technique may prove to be very helpful in identification of such categories of neuroglial cells that encompass also the images of cells which cannot be classified by use of the standard methods.
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  • 57
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    European archives of oto-rhino-laryngology and head & neck 233 (1981), S. 271-300 
    ISSN: 1434-4726
    Keywords: Neurogenic sarcoma ; Neurofibrosarcoma ; Malignant schwannoma ; Head and neck ; Tumors of the peripheral nervous system ; Histopathology ; Electron microscopy ; Differential diagnosis ; Case reports ; Computerized X-ray-tomography ; Prognosis ; Therapy ; Neurogenes Sarkom ; Neurofibrosarkom ; Malignes Schwannom ; Kopf- und Halsbereich ; Tumoren des peripheren ; Nervensystems ; Histopathologie ; Elektronenmikroskopie ; Differentialdiagnose ; Fallberichte ; Computertomografie ; Prognose ; Therapie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Das neurogene Sarkom ist ein insgesamt seltenes malignes Neoplasma, das sich von den Hüllen des peripheren Nerven ableitet. Entwickelt sich diese Geschwulst aus einem solitären oder multiplen Neurofibrom, so wäre nomenklatorisch auch die Bezeichnung Neurofibrosarkom gerechtfertigt, während alle anderen Synonyma für diese Geschwulst, insbesondere das maligne Schwannom, aus histogenetischen Gründen verlassen werden sollten. Für die Klassifizierung aller Tumoren des peripheren Nervensystems ist heute ein von der WHO (1969) akzeptierter Vorschlag zugrunde zu legen. Ein tabellarischer Literaturüberblick zeigt, daß in den letzten 50 Jahren nur über wenig mehr als 100 Fälle von neurogenen Sarkomen im Kopf-Halsbereich berichtet wurde. Die Differentialdiagnose dieses malignen Tumors umfaßt nahezu alle anderen malignen Weichgewebsgeschwülste und manchmal sogar ein anaplastisches Karzinom. Die Histopathologie, einschließlich der Elektronenmikroskopie, wird allgemein und an drei eingehenden Falldemonstrationen aufgezeigt, wobei auch den drei mikromorphologischen Varianten Rechnung getragen wird. Neben der feingeweblichen Untersuchung, die nur beim zusätzlichen Vorliegen einer Neurofibromatose oder bei der Identifizierung des Ursprungsnerven hundertprozentig gesichert werden kann, sind konventionelle und computertomografische Röntgentechniken zur Diagnosestellung hilfreich. Zum Schluß werden die Grundsätze der Therapie sowie die Prognose diskutiert.
    Notes: Summary The neurogenic sarcoma is a neoplasm found seldom. It descends from the sheaths of peripheric nerves. If this tumor develops from a solitary or multiple neurofibroma, it might also be called a neurofibrosarcoma. All other synonyms, especially that of the malignant schwannoma, should better be abandoned for histogenetic reasons. Today the classification of all tumors of the peripheral nervous system is based on a suggestion of the WHO from 1969. The tabular summary of the literature shows that only a little more than a hundred cases of neurogenic sarcoma of the head and neck were reported during the last 50 years. Differential diagnosis of this malignant tumor includes nearly all other malignant neoplasms of soft tissue, sometimes even anaplastic carcinoma. Histopathology, including electron microscopy, is described in general and also in detail with regard to three cases. Three forms of micro-morphological variants are dealt with, too. For diagnosis histological examination will be absolutely successful only in cases of neurofibromatosis or in cases where the nerve from which the tumor originates may be identified. Otherwise, conventional and computerized X-ray tomography may be helpful. Finally, some therapeutic and prognostic principles are discussed.
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  • 58
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    European archives of oto-rhino-laryngology and head & neck 230 (1981), S. 161-170 
    ISSN: 1434-4726
    Keywords: Sudden deafness ; Vertigo ; Neurectomy ; Eighth nerve ; Light microscopy ; Electron microscopy ; Demyelinating disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A patient initially presenting typical symptoms of idiopathic sudden deafness later developed disabling episodic vertigo, which led to translabyrinthine eighth nerve transection. Morphological examination of the removed cochlear nerve specimen revealed a demyelinating process in the neuroglial portion of the nerve. The major part of the peripheral, neurolemmal portion of the cochlear nerve was normal. The inferior vestibular nerve was fibrotic. The major part of the superior vestibular nerve was normal. Some of its peripheral bundles showed increased endoneurial fibrosis. It is suggested that a demyelinating process was the cause of the patient's symptoms.
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  • 59
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    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 19 (1981), S. 25-31 
    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: As an alternative to the density functional approach to estimating total molecular correlation energies, the equation Ecorr=-0.06593 ∑i=1M Ri-0.3916, where Ri=〈r2〉i½ and i runs over the localized molecular orbitals was fitted to 25 STO-3G data points with a root-mean-square error of 0.025 hartree. Other more general equations were tried but no significant improvement was observed in the fit.
    Additional Material: 2 Tab.
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  • 60
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    International Journal of Quantum Chemistry 19 (1981), S. 105-112 
    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 mechanical calculations have been made of vibrational transition probabilities in the collinear collision of an inert gas atom with either CO2 or OCS. The dependence of the transition probability on the relative translational energy and the reduced mass is similar to that found for atom-diatom collisions. The transition P00 → 10 (excitation of the first stretching mode) is much greater than P00 → 01 (the second stretching mode). This is largely due to the difference in frequencies but it has been shown that there is an independent mass factor responsible for this difference.
    Additional Material: 1 Ill.
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  • 61
    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: While the concept of the graph center is unambiguous (and quite old) in the case of acyclic graphs, an attempt has been made recently to extend the concept to polycyclic structures using the distance matrix of a graph as the basis. In this work we continue exploring such generalizations considering in addition to the distance matrix, self-avoiding walks or paths as graph invariants of potential interest for discriminating distinctive vertex environments in a graph of polycyclic structures. A hierachy of criteria is suggested that offers a systematic approach to the vertex discrimination and eventually establishes in most cases the graph center as a single vertex, a single bond (edge), or a single group of equivalent vertices. Some applications and the significance of the concept of the graph center are presented.
    Additional Material: 3 Ill.
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  • 62
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    International Journal of Quantum Chemistry 19 (1981), S. 251-257 
    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 this paper we define the algebraic structure of a reduced fermion density matrix. We relate the algebraic structure to certain symmetry properties of the reduced density matrix.
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  • 63
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    International Journal of Quantum Chemistry 19 (1981), S. 259-269 
    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 expansion of molecular orbital wave functions into valence bond (VB) functions is extended to molecular fragments. The wave function is projected onto a basis of mixed determinants, involving molecular orbitals as well as fragment atomic orbitals, and is further expressed as a linear combination of VB functions, characteristic of structural formulas of the fragment but whose remaining bonds are frozen. Structural weights for the fragment are deduced from this expression. Delocalized molecular orbitals are used as a startpoint, as they are after an ordinary SCF calculation. Wave functions of medium-sized molecules may be analyzed with reasonable storage requirements in a computer.
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  • 64
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    International Journal of Quantum Chemistry 19 (1981), S. 413-426 
    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 generalized branching diagram (GBD) spin representation is defined as the method of sequentially coupling together a number of subsystem spin eigenfunctions using the general rules of angular momentum coupling. It is shown that any GBD representation may also be obtained by Schmidt orthogonalizing a set of cannonical spin-paired (SP) functions, provided the SP basis is suitably ordered. The ordering procedure used is well suited to computer implementation. This is a generalization of results known in the literature for the Yamanouchi-Kotani and for the Serber spin representations.
    Additional Material: 4 Ill.
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  • 65
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    International Journal of Quantum Chemistry 19 (1981), S. 383-399 
    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 molecule-in-molecule method of computation has been applied in a SCF study of the electronic absorption spectra of 2- and 3-phenylfurans and 2,2′- and 3,3′-bifurans. The computed values for the transition energies and band intensities differ for the different isomers and help one to assign the preferred conformer of the studied molecules. Computations were performed on planar as well as nonplanar conformers. The calculated parameters as well as the interaction energy suggest all-planar configuration for the studied molecules. A model potential for the sigma framework for the ortho-hydrogens is considered. The calculated steric repulsion energy is negligible compared to the π delocalization. The height of the rotational barrier was larger for 2-phenylfuran than for 3-phenylfuran, and larger for 2,2′-bifuran than for 3,3′-bifuran. This result is in accord with predictions based on the extent of “π” conjugation in these molecules.
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  • 66
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    International Journal of Quantum Chemistry 19 (1981), S. 451-461 
    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 LCAO SCF MO calculations are carried out on the ground state and d-d transition states of CoF64-, CoF63-, and CoF62- complexes with a basis set of more than double-zeta quality. To obtain a better description for the excitation energy of d-d transition states, a ligand field configuration interaction calculation is performed. The calculation is improved further by taking into account the correlation energy in the central metal atom and it gives good results for the observed excitation energies. Especially, the excitation energies for the states which have the same configuration as the ground state agree with observed ones within about 1 kK. The excitation energies of several charge transfer states in the CoF62- complex are also computed at the level of SCF MO calculation and the assignments are made for the four strong bands observed in the energy region higher than the weak d-d bands.
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  • 67
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    International Journal of Quantum Chemistry 19 (1981), S. 483-484 
    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
    Additional Material: 1 Tab.
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  • 68
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    International Journal of Quantum Chemistry 19 (1981), S. 505-514 
    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 properties of the algebraic structure of fermion density matrices are studied. The algebraic structure of a density matrix leads to a more varied and detailed classification scheme than that offered by the usual shell structure approach. Investigation of the algebraic structure of fermion density matrices by the methods of algebraic topology leads to a classification scheme based on Betti numbers.
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  • 69
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    International Journal of Quantum Chemistry 20 (1981) 
    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
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  • 70
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    International Journal of Quantum Chemistry 20 (1981), S. 41-48 
    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: Synchrotron radiation has been used to determine the fluorescence decay parameters of a tryptophan-containing oligopeptide, Lys-Trp-Lys, bound to nucleic acids. All fluorescence decay curves can be fitted by a sum of two exponentials. The two lifetimes very likely correspond to two conformational states of the oligopeptide. The mean fluorescence lifetime of the peptide is not markedly affected upon binding to nucleic acids even though the fluorescence quantum yield is strongly reduced. A model is presented that accounts for the existing fluorescence data: two consecutive complexes are formed both involving electrostatic interactions. In one of the complexes the tryptophyl ring is stacked with the nucleic acid bases and its fluorescence is completely quenched. The other complex emits a fluorescence having characteristics which are similar to those of the free peptide.
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  • 71
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    International Journal of Quantum Chemistry 19 (1981), S. 1099-1103 
    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: After emphasizing the importance of absorption spectra of metal clusters, with special reference to alkali halide IR absorption, the equilibrium configurations and the binding energies of alkali halide clusters are discussed in terms of a very simple two-body interaction.
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  • 72
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    International Journal of Quantum Chemistry 19 (1981), S. 1133-1135 
    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
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  • 73
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    International Journal of Quantum Chemistry 20 (1981), S. 167-178 
    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 paper reports comparison of electrostatic charge and energy distribution on the basis of the CNDO/2 method for six forms of prostaglandins-PGF2α, PGF1β, PGE1, PGE2, PGB1, and PGA1-having diverse physiological action. The isopotential mapping done in three dimension showed that the lower value of electrostatic potential and proximity of the two low energy regions around O9 and O11 in PGE2 and PGF2α is probably responsible for their higher abortificient activity. We also compare here the variation of the long- and short-range interaction between ring-chain and chain-chain portion of different forms and compared them with the variation in their action.
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  • 74
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    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 ab initio pseudopotential and CNDO calculations on γ-aminobutyric acid (GABA) and its Ca2+ and Mg2+ clathrates. We were particularly interested in the rotational barrier existing between two extreme conformers of GABA and its modification upon metal complexing. We found that the pseudopotential method predicts a coordination of the ions to GABA and that this coordination inverts the rotational barrier observed for the isolated molecule. We also looked into the adequacy of CNDO for the study of this type of coordination and found several shortcomings in its predictions. The biological implications of these findings are discussed and a hypothesis on the role of a GABA-Ca2+ complex is presented.
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  • 75
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    International Journal of Quantum Chemistry 19 (1981) 
    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
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  • 76
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    International Journal of Quantum Chemistry 19 (1981), S. 493-500 
    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 the frame of direct minimization of MC-SCF energy by an orthogonal transformation of the basis, a new procedure for iteratively solving the orbital equations is presented, in which the orthogonal matrix is calculated by the singular value and vector decomposition of a nonsymmetric matrix. The procedure is applied to the self-consistent electron pair theory and tested on LiH molecule. Convergence rate and numerical stability are found to be satisfactory.
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  • 77
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    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 for basis set generation for SCF calculations is proposed. Using SCF orbitals and orbital energies obtained in the extended basis set the Fock operator can be expressed as its spectral resolution. The sum of differences between occupied orbital energies and corresponding eigenvalues obtained by the diagonalization of this operator in the new smaller basis set is a criterion of the quality of this new set. The present method consists of the minimization of this sum by changing the parameters that determine the new basis functions. An example of the optimization of the different Gaussian basis sets for the LiH molecule is described.
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  • 78
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    International Journal of Quantum Chemistry 19 (1981), S. 637-648 
    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: An SCF LCAO MO calculation on the methane-methane-methane system is presented, in order to analyze the deviation from pairwise additivity of the interaction energy. Three-body terms are shown to be remarkably similar to those of noble gas trimers both in magnitude and in their dependence on the geometrical arrangements of the three molecules.
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  • 79
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    International Journal of Quantum Chemistry 19 (1981), S. 673-679 
    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: Making use of different information measures, the Pauli exclusion principle and the first Hund rule were found to be related to a trend toward acquiring a maximum information content of the atoms and molecules, and more generally, for any fermion system. The bosons conversely always have a minimum (zero) information content with respect to the permutation symmetry of their wave functions. Some new interpretations of the Pauli principle are presented.
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  • 80
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    International Journal of Quantum Chemistry 19 (1981), S. 681-691 
    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 first principles method based on an APW-k · p band structure calculation is derived in order to obtain the self-consistent eigenenergies, crystal potential, and electronic density. The simplicity and extensions of the method are discussed, including comparison with the results obtained by the use of the Chadi and Cohen special points technique.
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  • 81
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    International Journal of Quantum Chemistry 19 (1981), S. 719-720 
    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
    Additional Material: 1 Ill.
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  • 82
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    International Journal of Quantum Chemistry 19 (1981), S. 729-734 
    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: An analytic atomic active electron model potential adjusted to experimental single-particle energy levels is used to generate wave functions for the valence and excited states of O1+, F2+, Ne3+, Na4+, and Mg5+. Using these wave functions in conjunction with the Born approximation and the LS-coupling scheme, we calculate optical oscillator strengths for excitations from the 1s22s22p3(4S3/2) ground state. The results are compared to experimental data and other calculations. Systematic trends along the isoelectronic sequence are discussed.
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  • 83
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    International Journal of Quantum Chemistry 19 (1981), S. 763-769 
    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 coupled perturbation theory for the antisymmetrized product of separated geminals (APSG) approximation is derived. The variational principle for the APSG wave function in an external oscillating field is employed and a set of equations of the form analogous to the normal RPA is obtained. At this level the reduced resolvent in the form of a spectral expansion is written and it is used for the evaluation of the second-order properties.
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  • 84
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    International Journal of Quantum Chemistry 19 (1981), S. 805-819 
    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 charge density distribution study, based on ab initio SCF-6-31G wave functions, on the optimized geometry of 1,2-dioxethane indicates its high instability which results from (i) the high ring strain, (ii) the large amount of charge contained on the nonbonded sides of the oxygen nuclei, and (iii) the weak binding character of the charge density in the O—O bond region. The redistribution of the charge density when 1,2-dioxethane undergoes change in its nuclear configuration has been discussed. This redistribution of charge along the reaction path (the dissociation of 1,2-dioxethane to formaldehyde products) shows clearly the preceding nature of the electron cloud. The characteristic features of the charge density distribution of the two Hartree-Fock solutions to which the SCF procedure converges have been analyzed and discussed.
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  • 85
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    International Journal of Quantum Chemistry 19 (1981), S. 859-871 
    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: By applying the projection operator method it is shown that the complicated Hamiltonian of a E ⊗ ∊ JT system with nonlinear coupling coefficients can be written in terms of two Hamiltonians which are simple to handle and transform according to irreducible representations E, A1, and A2 of C3v point group. A variational approach is then used to calculate the ground state energy, using the Hamiltonian that transforms according to E, as an explicit function of the linear and nonlinear coupling parameters. The energies calculated in the strong coupling limit are finally compared with the corresponding previously calculated energies.
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  • 86
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    International Journal of Quantum Chemistry 19 (1981), S. 901-906 
    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 coupled channel formulation for the static Stark effect on the hydrogen atom is used to obtain directly the complex resonance energies through an iterative matching procedure. The formulation makes use of a complex coordinate. This solves the initialization problem in a very simple way, since the boundary conditions can be those used for bound states. A comparison is made with the results of Reinhardt and collaborators who expand the complex rotated resonance wave function in a basis of integrable functions.
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  • 87
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    International Journal of Quantum Chemistry 20 (1981), S. 347-356 
    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: Single chain and packing energy calculations have been made on polyglycine (threefold and fourfold helical structures) with interchain NH…O hydrogen bonds. In conformation A of polyglycine, in which the NH groups point away from the helix axis and the CO groups are nearer to the helix axis, the conformational energy is nearly the same for threefold and fourfold structures. However, the minimum energy conformation corresponds to a threefold structure of polyglycine with peptide configurations in conformation B in which the CO groups point away from the helix axis and NH groups are nearer to the helix axis. This structure is consistent with the polyglycine II x-ray diffraction data.
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  • 88
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    International Journal of Quantum Chemistry 20 (1981), S. 393-406 
    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 ab initio MO and semiempirical multireference (MR) CI calculations were carried out to elucidate the energy differences between peroxy 1,4-diradical (DR) and 1,4-zwitterionic (ZWI) intermediates, which play crucial roles in photo-oxygenation reactions of nitrogen-activated C—C double bonds of enamines, indoles, and tryptamines. It is found that ZWI is more stable than DR in the case of electron-rich enamines. Protic solvents such as methanol are highly effective for the stabilization of ZWI by hydrogen bondings. From the present theoretical results, it is concluded that tryptophane undergoes the photooxidative cleavage reaction to give formylkynurenine under a specific condition, where polar solvents or catalysts sufficiently stabilize the ZWI state for the species.
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  • 89
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    International Journal of Quantum Chemistry 20 (1981), S. 461-478 
    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 state in the chemistry of peptides and proteins capable of transporting ions across biological and model membranes have been reviewed. The mechanisms of action of peptide ionophores valinomycin and enniatin and also the channel-forming peptide gramicidin-A have been discussed on the basis of spatial structure and dynamic conformational properties of the compounds. Recent progress in the studies of bacteriorhodopsin, cholinergic receptor from postsynaptic membrane, and sodium channel from the excitable nerve membrane, the integral membrane proteins acting as proton or metal ion channel formers is also discussed.
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  • 90
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    International Journal of Quantum Chemistry 20 (1981), S. 495-504 
    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 water structure around model membrane systems (e.g., liposomes) on phase transition of the lipid dipalmitoyl phosphatidylcholine was investigated. Water structure was altered by changing pH and by addition of solutes which are known breakers and makers of water structure. The structure makers broadened the zone of transition and changed the overall phase transition profile, while the main effect of structure breakers was to cause a shift in the transition temperature. The observed variation of Chapman transition temperature and broadening of zone of transition with varying pH is discussed in terms of altered water structure around the membrane-aqueous interface. Binding studies with the dye 1-anilino-8-napthalene sulfonate showed that structure makers or breakers did not bind to the liposome surface directly. Thus the structure makers and breakers act on the membranes perhaps by altering the water structure differentially. Possible associated mechanisms of action are discussed.
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  • 91
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    International Journal of Quantum Chemistry 20 (1981), S. 543-554 
    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: Infrared spectroscopy has been employed to study possible base pair interactions, in nonpolar media, between O6-methylguanine and uracil, cytosine and adenine; and between derivatives of N4-hydroxycytosine and adenine. The association constants of O6-methylguanine with uracil, cytosine, and adenine are well below 1M-1, whereas those for interaction of 1-methyl-N4-methoxycytosine and its 5-methyl derivative with adenine are identical, K = 14M-1. The significance of the latter finding is discussed in relation to the conformation of the exocyclic N4-methoxy group. Quantum chemical calculations, with the aid of the perturbation method, were carried out for the interaction of O6-methylguanine with uracil, cytosine, and adenine, to establish the most energetically favoured configurations for interactions of the free bases, and of the same base pairs in the B form of DNA. The role of the conformation of the exocyclic  - OCH3 group in O6-methylguanine is discussed. The relevance of both the experimental and theoretical results to mutagenesis by O6-methylguanine and N4-hydroxycytosine is examined.
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  • 92
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    International Journal of Quantum Chemistry 20 (1981) 
    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
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  • 93
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    International Journal of Quantum Chemistry 20 (1981), S. 843-859 
    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: An ab initio LCAO SCF MO calculation was performed on planar Fe-porphine with a double zeta basis set consisting of 300 CGTO's. SCF wave functions of several states of Fe-porphine and its cation were obtained. The net charge of Fe is in the range of 1.39 to 1.53. The highest occupied orbital is ascertained to be a pure porphine π-MO, 1a1u. The calculated ionization potentials of the two highest occupied orbitals, 1a1u and 5a2u are 5.98 and 6.43 eV, respectively. They are in good agreement with experiments. The role of the porphine macrocycle on the oxidation of Fe is discussed in terms of gross atomic populations and with contour maps of the density difference.
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  • 94
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    International Journal of Quantum Chemistry 20 (1981), S. 887-889 
    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 limiting of the 〈r12-1〈/〈r1-1〈 ratio in the He sequence is critically examined at different levels of approximations leading to some interesting results.
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  • 95
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    International Journal of Quantum Chemistry 20 (1981), S. 921-926 
    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: Along the lines of previous work [S. Romano and E. Clementi, Gazz. Chim. Ital. 108, 319 (1978); Int. J. Quantum Chem. 14, 839 (1978); 17, 1007 (1980)], we carried out Monte Carlo simulation on serine-water clusters (the neutral molecule and two conformers of the zwitterion) surrounded by an appropriate dielectric continuum simulating the bulk solvent. Results for clusters in vacuo and in the dielectric continuum were compared; similarities and differences could be qualitatively interpreted as produced by competition among different factors.
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  • 96
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 20 (1981), S. 933-949 
    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 self-consistent APW-k · p method is utilized to obtain the band structure of NaCl in the “muffin-tin” approximation. Qe have investigated the convergence of many intermediate results, e.g., crystalline potential, matrix elements of the momentum operator, and energy eigenvalues at the Γ point. The summation in reciprocal space, included in the definition of the matrix D of the theory, is performed by direct sum and also by a special points technique. For the convergence criteria used, the results converged after five iterations.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 97
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 20 (1981), S. 1073-1076 
    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: Generalized oscillator strengths and integrated cross sections from threshold to 1 keV are calculated in the Born approximation for the electron impact excitation of O II.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 98
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 20 (1981), S. 1067-1071 
    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-electron properties may be evaluated by configuration interaction methods using analytical differentiation of the total energy with respect to an external perturbation parameter. Dipole moments are reported using such a method for CO and H2CO. Inclusion of single substitutions does not change calculated dipole moments appreciably with this method. The differences between this method and the direct evaluation of an expectation value are discussed.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 99
    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 are engaged in research directed toward the development of compact and accurate correlation functions for many-electron systems. Our computational tool is the variational method in which the many-electron integrals are calculated by Monte Carlo using the fermion Metropolis sampling algorithm. That is, a many-fermion system is simulated by sampling the square of a correlated antisymmetric wave function. The principal advantage of the method is that interelectronic distance rij may be included directly in the wave function without adding significant computational complexity. In addition, other quantities of physical and theoretical interest such as electron correlation functions and representations of Coulomb and Fermi “holes” are very easily obtained. Preliminary results are reported for He, H2, and Li2.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 100
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 20 (1981), S. 1165-1177 
    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 recently proposed orthonormality constrained orbital optimization technique is operationally modified further by coupling it to a gradient biased method, namely the steepest descent procedure of McWeeny. The hybrid technique developed in this way is shown to have better convergence properties in closed and unrestricted open-shell calculations. The technique can be adapted to MCSCF procedures as well. The important role played by "orbital symmetries" in the operation of the method is analysed. Similarities and differences of the present method with the orthogonal gradient method are pointed out. Possible avenues of circumventing convergence difficulty that one may encounter in pathological cases, particularly in ab initio calculations involving extended basis set, are suggested.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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