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  • 1995-1999  (1.403)
  • 1975-1979  (304)
  • 1970-1974
  • 1920-1924
  • 1890-1899
  • 1995  (1.403)
  • 1978  (304)
  • Biochemistry and Biotechnology  (1.496)
  • Electron microscopy  (211)
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Erscheinungszeitraum
  • 1995-1999  (1.403)
  • 1975-1979  (304)
  • 1970-1974
  • 1920-1924
  • 1890-1899
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Lasers in medical science 10 (1995), S. 93-104 
    ISSN: 1435-604X
    Schlagwort(e): Copper vapour laser ; Electron microscopy ; Illumination time ; Numerical modelling ; Optimal treatment ; Port-wine stain
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract This paper reports the electron microscopy results obtained from two patients who were treated with 5 W of yellow (578 nm) light from a copper vapour laser with an illumination time of 3.6 ms and a 0.3 mm spot diameter. The endpoint of treatment was transient blanching. Following treatment, erythema was observed. There was minimal damage to the epidermis and non-vascular tissue such as the nerve fibres. There was severe damage to the endothelial cells of the ectatic vessels. Twenty-four hours after treatment, platelet activation and collagen were present, indicating that these vessels were no longer viable. Theoretical calculations are used to determine the flow of heat within and away from a 50μm diameter vessel. From this, heating of the entire vessel is shown to occur with illumination times of 4 ms, with minimal heating of the non-vascular tissue. Shorter illuminations do not heat the entire vessel, while the use of longer illumination times will cause excessive damage to the surrounding non-vascular tissue. Illumination times close to 4 ms must be regarded as optimal.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular medicine 73 (1995), S. 73-77 
    ISSN: 1432-1440
    Schlagwort(e): Chloroquine ; Cardiomyopathy ; Heart ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Light microscopic and ultrastructural findings in patients suffering from chloroquine-induced cardiomyopathy are reviewed. Based on our own observations in an autopsy case, functional and morphological similarities between chloroquine effects and hereditary lysosomal storage diseases are discussed.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1432-2307
    Schlagwort(e): Graft-versus-host disease ; Cell blebs ; Light microscopy ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Subnuclear blebbing of the superficial colonic epithelium, a rarely described light and electron microscopic change in graft-versus-host disease (GVHD), was studied in a murine model of GVHD. Severity of changes induced by transfer of various donor T cell subsets to irradiated, allogeneic recipients, and association with more severe alterations such as erosions and ulceration were evaluated. By light microscopy the basal region of the superficial enterocytes was greatly expanded by eosinophilic to amphophilic, flocculent, sometimes vacuolated material. By electron microscopy these changes were found to be organelle-poor, cytoplasm-filled protrusions from the basal surface of the epithelium. In this model, helper T cells (CD4+-enriched, CD8+-depleted T cells) transplanted after high dose irradiation were capable of causing the change suggesting cytokine responses may be involved in mediating the cellular injury seen histologically. Close association of blebbing and erosions suggest the blebbing may be the precursor to epithelial erosion or denudation seen in severe intestinal GVHD.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1432-2307
    Schlagwort(e): Giant cell tumour of bone ; In vitro resorption ; Leukaemia inhibitory factor ; Synthetic calcium phosphate ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Osteoclastic cells from giant cell tumour of bone (GCT) of bone provide a rich source for investigation of cellular mechanisms leading to formation of multinucleated cells, the resorption process and involvement of hormones and cytokines in these events. In the present study we investigated the effect of 1,25-dihydroxyvitamin D3 (VD3) and leukaemia inhibitory factor (LIF) on the resorbing potential of osteoclast of GCT origin using quantitative image-analysis of resorption lacunae in an in vitro dentine model. While VD3 unsignificantly increased the number of resorption pits and implicated surface after 7 days of GCT cell culturing, the stimulative effect of LIF was statistically significant. In cultures supplemented with LIF (5000 U/ml) the number of lacunae and resorption surface increased by 38% and 55%, respectively, when compared with control cultures. We suggest that both osteotropic agents increased osteoclastic activity, as the number of multinucleated cells was similar in control and experimental cultures. Seeding of GCT cells on biphasic calcium phosphate substratum revealed the relative inability of osteoclastic cells to resorb this synthetic material.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Virchows Archiv 426 (1995), S. 523-528 
    ISSN: 1432-2307
    Schlagwort(e): Von Hippel-Lindau disease ; Neuroendocrine tumour ; Electron microscopy ; Flow cytometry ; Immunohistochemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A 21-year-old woman with a family history of von Hippel-Lindau disease presented with a mass in the head of the pancreas. Light microscopic features of the tumour suggested neuroendocrine differentiation and although it displayed positive immunostaining for the antigens expected in a neuroendocrine neoplasm, S-100 staining was also present. This unusual feature prompted further evaluation by routine and post-embedding protein-A gold immunoelectron microscopy, which demonstrated the presence of neuroendocrine granules. Tumour cell DNA content was normal by flow cytometry. Although this patient exhibited no other signs of von Hippel-Lindau disease, the presence of a pancreatic tumour with neuroendocrine differentiation demonstrated that she was affected. Future surveillance and genetic counselling will be influenced by this diagnosis.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1572-9648
    Schlagwort(e): Electron microscopy ; Microstructures ; Phase transitions ; Solid mechanics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Beschreibung / Inhaltsverzeichnis: Sommario Si presentano i risultati di alcuni studi fatti attraverso la microscopia elettronica sulle microstrutture relative a transizioni di fase in una varietà di materiali. I casi comprendono leghe binarie e ternarie, superconduttori TC e materiali C60 e C70; le transizioni esaminate sono diffusionali, displacive o di entrambi i tipi.
    Notizen: Abstract In this contribution the results of some electron microscopy studies on microstructures related with phase transitions in a variety of materials will be presented. The materials include binary and ternary alloys, high TC superconductors as well as C60 and C70 fullerenes, while the transitions can be diffusional, displacive or both.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1432-0533
    Schlagwort(e): Key words Tonsillar herniation ; Syringomyelia ; Chiari malformations ; Histology ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract This report describes an experimental model of chronic tonsillar herniation and its effects on the spinal cord. In ten rats, a small piece of chemically induced mammary cancer was transplanted to the supraoccipital bone. In all cases, the transplanted cancers grew into the posterior fossa, destroying the supraoccipital bone and compressing the cerebellum extradurally. In six of the ten rats, tonsillar herniation was observed at 8–14 weeks after transplantation. Transdural infiltration of the tumor cells was not apparent in any animal. In those rats with tonsillar herniation (n = 6), the spinal cord from the C5 to the T8 segments showed enlargement of the central canal without exception. Histological examination revealed the following changes: stretching and thinning of the ependymal cells; swelling of the astrocytic processes; and extracellular edema, predominantly in the dorsal gray matter, but also in the ventral inner portion of the dorsal column. In the control group (n = 4) and those rats without tonsillar herniation (n = 4), such histological changes of the spinal cord were not observed. Although the lesions can not be regarded as representing mature syringomyelia, they most likely constitute an earlier evolutionary stage.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 192 (1995), S. 265-274 
    ISSN: 1432-0568
    Schlagwort(e): Lymphatics ; Valves ; Microanatomy ; Vimentin filaments ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The microanatomy and ultrastructure of the feline and canine thoracic duct and afferent lymphatics were studied by scanning and transmission electron microscopy. We found that the lymphatic vessels were always terminated by ostial valves of two shapes, crescent- and navicular-like, in a ratio of 4∶1. Specific regulatory structures along the free edges of the valves, including marginal thickenings and buttresses, are described. The tissue and cellular organization of the valve endothelium showed distinct peculiarities, particularly in the orientation and shape of the cells and their microrelief. We found that valvular endothelial cells, especially „tip cells”, which are situated in unfavourable lymphodynamic conditions, were characterized by an increased volume density of intermediate (probably vimentin-based) filaments, suggesting an accommodative mechanism involving such filaments.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 90 (1995), S. 425-431 
    ISSN: 1432-0533
    Schlagwort(e): Tonsillar herniation ; Syringomyelia ; Chiari malformations ; Histology ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract This report describes an experimental model of chronic tonsillar herniation and its effects on the spinal cord. In ten rats, a small piece of chemically induced mammary cancer was transplanted to the supraoccipital bone. In all cases, the transplanted cancers grew into the posterior fossa, destroying the supraoccipital bone and compressing the cerebellum extradurally. In six of the ten rats, tonsillar herniation was observed at 8–14 weeks after transplantation. Transdural infiltration of the tumor cells was not apparent in any animal. In those rats with tonsillar herniation (n=6), the spinal cord from the C5 to the T8 segments showed enlargement of the central canal without exception. Histological examination revealed the following changes: stretching and thinning of the ependymal cells; swelling of the astrocytic processes; and extracellular edema, predominantly in the dorsal gray matter, but also in the ventral inner portion of the dorsal column. In the control group (n=4) and those rats without tonsillar herniation (n=4), such histological changes of the spinal cord were not observed. Although the lesions can not be regarded as representing mature syringomyelia, they most likely constitute an earlier evolutionary stage.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 90 (1995), S. 194-197 
    ISSN: 1432-0533
    Schlagwort(e): Key words Alzheimer's disease ; Paired helical ; filaments ; Electron microscopy ; Tau
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract To investigate if Alzheimer paired helical filaments (PHF) closely resemble twisted ribbons, as indicated by recent high-resolution ultrastructural studies, we compared physical models of twisted ribbons with electron microscopic images of PHF. Uranyl-acetate-stained, isolated PHF with one or two helical turns were compared with scale models of twisted ribbons with one and two helical turns rotated at different angles. The various rotations of the twisted ribbon model corresponded well with the different orientations of randomly dispersed PHF. The electron-dense regions of individual PHF turns previously thought to represent a cross-over site of paired filaments corresponded to the edge of the twisted ribbon when the ribbon was oriented perpendicular to the filament axis. These data indicate that the overall configuration of PHF is a twisted ribbon but does not exclude possible configuration restrictions due to an ordered arrangement of subunits.
    Materialart: Digitale Medien
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 90 (1995), S. 194-197 
    ISSN: 1432-0533
    Schlagwort(e): Alzheimer's disease ; Paired helical filaments ; Electron microscopy ; Tau
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract To investigate if Alzheimer paired helical filaments (PHF) closely resemble twisted ribbons, as indicated by recent high-resolution ultrastructural studies, we compared physical models of twisted ribbons with electron microscopic images of PHF. Uranyl-acetate-stained, isolated PHF with one or two helical turns were compared with scale models of twisted ribbons with one and two helical turns rotated at different angles. The various rotations of the twisted ribbon model corresponded well with the different orientations of randomly dispersed PHF. The electron-dense regions of individual PHF turns previously thought to represent a cross-over site of paired filaments corresponded to the edge of the twisted ribbon when the ribbon was oriented perpendicular to the filament axis. These data indicate that the overall configuration of PHF is a twisted ribbon but does not exclude possible configuration restrictions due to an ordered arrangement of subunits.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 89 (1995), S. 85-95 
    ISSN: 1432-0533
    Schlagwort(e): Neonatal de-efferentation ; Sensory denervation ; Electron microscopy ; Intrafusal muscle fibre types ; Postnatal myogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The ultrastructure of muscle spindles de-efferented by the extirpation of the lumbosacral spinal cord at the age of 2 days and subsequently deprived of their sensory innervation by the section of the sciatic nerve at 3–4 weeks of age was studied in serial sections of 2-month-old rat hindlimb muscles. De-efferentation leaves the primary sensory neurons and their peripheral axons intact and capable of inducing the muscle spindle morphogenesis during the critical period of their development. In de-efferented and subsequently denervated muscle spindles, new supernumerary intrafusal muscle profiles (SIPs) appeared in the muscle spindle A region. They were formed in intimate spatial relation with the original intrafusal muscle fibres (IMFs) predominantly from activated satellite cells derived from both nuclear bag (larger diameter) and nuclear chain fibres. SIPs, however, lacked the typical nuclear accumulations, as well as other ultrastructural distinctions present in control IMFs. The majority of differentiated SIPs separated from original IMFs, whereas the less differentiated SIPs were usually closely apposed to the surface of the parent IMFs and both were covered by the common basal lamina. In some spindles, the original IMFs and/or new SIPs at different stages of their differentiation were found together and they formed clusters of variable shape and composition. In the majority of clusters, all profiles seemed to be isolated along their entire length, although in few clusters, occasional cytoplasmic connections of variable length between intrafusal profiles were found. This result is important for the interpretation of the forthcoming study of expression of muscle spindle-specific myosin heavy chain isoforms in denervated SIPs in rat muscle spindles gradually deprived of their motor and sensory innervation.
    Materialart: Digitale Medien
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  • 13
    ISSN: 1432-0533
    Schlagwort(e): Astrocytes ; Alzheimer's disease ; Electron microscopy ; Paired helical filaments ; Straight tubules
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Ultrastructural investigation of the hippocampal CA1 and CA4 of nine sutopsy-proven cases of dementia of the Alzheimer type (duration of disease: 3–16 years; age: 76–92 years) revealed paired helical filaments (PHFs) and straight tubules (STs) in astrocytes of three advanced cases of long duration (〉13years). The PHFs and STs were indistinguishable from those seen in neurons. The abnormal glial fibrils were confined to the astrocytic processes that were associated with small vessels or, more frequently, with ghost tangles. In both locations the astrocytic PHFs and STs were located in the cytoplasm without limiting membranes, and were thicker than the straight filaments that composed ghost tangles. These findings, combined with the presence of regular constrictions of astrocytic PHFs, suggest that abnormal astrocytic fibers are produced by the glial cells, not engulfed by them. In addition, the presence of these abnormal glial filaments in only advanced, long-duration cases of dementia of the Alzheimer type suggests that disease duration has a significant effect upon the formation of these astrocytic profiles.
    Materialart: Digitale Medien
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  • 14
    ISSN: 1432-0533
    Schlagwort(e): Key words Astrocytes ; Alzheimer's disease ; Electron microscopy ; Paired helical filaments ; Straight tubules
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Ultrastructural investigation of the hippocampal CA1 and CA4 of nine autopsy-proven cases of dementia of the Alzheimer type (duration of disease: 3–16 years; age: 76–92 years) revealed paired helical filaments (PHFs) and straight tubules (STs) in astrocytes of three advanced cases of long duration (〉13 years). The PHFs and STs were indistinguishable from those seen in neurons. The abnormal glial fibrils were confined to the astrocytic processes that were associated with small vessels or, more frequently, with ghost tangles. In both locations the astrocytic PHFs and STs were located in the cytoplasm without limiting membranes, and were thicker than the straight filaments that composed ghost tangles. These findings, combined with the presence of regular constrictions of astrocytic PHFs, suggest that abnormal astrocytic fibers are produced by the glial cells, not engulfed by them. In addition, the presence of these abnormal glial filaments in only advanced, long-duration cases of dementia of the Alzheimer type suggests that disease duration has a significant effect upon the formation of these astrocytic profiles.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Anatomy and embryology 192 (1995), S. 257-264 
    ISSN: 1432-0568
    Schlagwort(e): Cholinesterases ; Electron microscopy ; Development ; Mouse embryo ; Somites
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract During the development of somites in mouse embryos, widespread activity of unspecific cholinesterase (BuChE) was demonstrated after prolonged incubation. Independent of their position, all somite cells and their derivatives (dermatome, myotome and sclerotome) exhibited enzyme activity in the perinuclear space and in the endoplasmic reticulum. The plasmalemma did not show any enzyme activity. Differentiation of the sclerotome into vertebrae was accompanied by a reduction of BuChE. However, a low enzyme reaction was still present in the first typical differentiated chondroblasts. Notochordal cells were detectable by their high BuChE content. This was also found in cells already showed severe degeneration. In addition to BuChE, acetylcholinesterase (AChE) was first visible on day 9 of embryonic development in newly formed myotubes of the myotomes. Some hypotheses on the functional significance of embryonic BuChE are discussed in the light of these results.
    Materialart: Digitale Medien
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  • 16
    ISSN: 1432-0827
    Schlagwort(e): Bone sialoprotein ; osteoblast ; Bone matrix ; Electron microscopy ; Immunolocalization ; noncollagenous protein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract Bone sialoprotein was immunolocalized at the EM level in thin Lowicryl K4M sections of rat bone. Because of the unconventional EM morphology of the bone matrix seen in thin demineralized acrylate sections, the pattern of immunolabeling was compared with detailed structural images of demineralized bone obtained using an en bloc treatment of tissue samples with the cationic electron ‘dye’, Malachite Green (MG), which provides stabilization and retention of anionic material throughout specimen processing. A system of structures corresponding to the sites of bone sialoprotein (BSP) immunoreactivity, as seen in Lowicryl K4M thin sections, could be readily identified in the MG-treated, expoxy thin sections. This system includes the cement lines, and aggregates of similar material within mineralized bone and mineralizing osteoid. The virtual identity of BSP distribution with the arrangement of the MG-visualized material indicates that a BSP-enriched, noncollagenous phase can be demonstrated using different, unrelated tissue preparation and imaging protocols for EM. Besides improving our understanding of the distribution of bone sialoprotein in bone, these data assign a previously unrecognized structural dimension to noncollagenous material in the bone matrix.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 56 (1995), S. 566-570 
    ISSN: 1432-0827
    Schlagwort(e): Cathepsin inhibitors ; Osteoclasts ; Resorption ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Abstract This study was designed to evaluate the effects of specific and potent cathepsin inhibitors on osteoclastic resorptive functions in vitro by means of a novel ultrastructural assay system. Mouse bone marrow cell-derived osteoclasts were suspended on dentine slices and cultured for 48 hours in the presence of either E-64 (a generalized cysteine proteinase inhibitor) or Z-Phe-Phe-CHN2 (a selective cathepsin L inhibitor). After the removal of cultured osteoclasts, co-cultured dentine slices were examined using electron microscopy: backscattered (BSEM), scanning (SEM), and atomic force (AFM). In morphometric analyses of BSEM images, there were no significant differences in the areas of demineralized dentine surfaces between control and inhibitor-treated groups, suggesting that cathepsin inhibitors had no effect on dentine demineralization by cultured osteoclasts. However, in SEM and AFM observations, both inhibitors remarkably reduced to the same extent, the formation of deep resorption lacunae on dentine slices that had resulted from degradation of matrix collagen. In addition, Z-Phe-Phe-CHN2 treatment produced deeper, ring-like grooves with little collagen exposure in shallow resorption lacunae. These results strongly suggest that (1) cathepsins released by osteoclasts are involved in the formation of deep resorption lacunae, and (2) cathepsin L plays a key role in bone resorption.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Intensive care medicine 21 (1995), S. 482-489 
    ISSN: 1432-1238
    Schlagwort(e): Mucociliary clearance ; Ultrastructural ciliary alterations ; Cilia ; Electron microscopy ; Intubation ; Mechanical ventilation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Objective The objective of this study was to investigate whether reduced bronchial mucus transport velocity (BTV) is associated with a loss of cilia or ultrastructural abnormalities of cilia in intubated patients. Design The patients were studied prospectively in a convenience sample trial. Setting The study took place in a university hospital. Patients and participants 29 orally intubated patients in a surgical ICU. Interventions BTV was measured with radiolabeled microspheres in the right and left primary bronchus. Following these measurements, biopsy samples were taken from the bronchi for scanning (SEM) and transmission (TEM) electron-microscopic investigations. Measurements and results SEM: Patients with normal or slight impaired BTV (group 1,n=14: BTV: 8.5 mm/min (3.8–11.5); median with range) showed more cilia on the luminal surface than patients with markedly depressed BTV (p〈0.05) (group 2,n=15: BTV: 0(0–2.1)). The difference was statistically significant. The BTV values correlated moderately with the number of cilia on the luminal surface (r=0.46;p=0.02). TEM: In group 1, 6.5% (3.9–14.9) of cilia were abnormal (median with range) vs 9.3% (4.9–13.7) in group 2; these differences were not statistically significant. Neither was there any significant correlation between BTV and the frequency of abnormal cilia. Conclusions Impaired mucociliary transport in intubated patients is associated with a loss of cilia rather than ultrastructural abnormalities of cilia, which are less relevant.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Der Hautarzt 46 (1995), S. 785-788 
    ISSN: 1432-1173
    Schlagwort(e): Schlüsselwörter Angiokeratoma corporis diffusum ; Lysosomale Stoffwechselstörung ; Elektronenmikroskopie ; Kapillarmikroskopie ; Key words Angiokeratoma corporis diffusum ; Lysosomal disorder ; Electron microscopy ; Capillary microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary In a 22-year-old woman with mental impairment and some signs of dysmorphism, numerous angiokeratomas developed, starting when she was 3 years old and resulting in the clinical picture of angiokeratoma corporis diffusum. Extensive laboratory analyses did not disclose any associated metabolic disorder, and electron microscopy failed to demonstrate lysosomal inclusions. Therefore, this patient can be classified as one of the rare cases of angiokeratoma corporis diffusum without associated metabolic disease (idiopathic angiokeratoma corporis diffusum).
    Notizen: Zusammenfassung Bei einer 22jährigen Patientin mit ausgedehnten, ab dem 3. Lebensjahr auftretenden Angiokeratomen im Sinne eines Angiokeratoma corporis diffusum, welche zusätzlich eine Intelligenzminderung und Dysmorphiezeichen aufwies, konnte trotz intensiver Suche laborchemisch keine assoziierte Stoffwechselstörung gefunden werden. Der fehlende Nachweis einer lysosomalen Speicherung in der Elektronenmikroskopie stützte diesen Befund. Somit liegt bei dieser Patientin die seltene Situation eines Angiokeratoma corporis diffusum ohne assoziierte Stoffwechselkrankheit (idiopathisches Angiokeratoma corporis diffusum) vor.
    Materialart: Digitale Medien
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Der Pathologe 16 (1995), S. 404-407 
    ISSN: 1432-1963
    Schlagwort(e): Schlüsselwörter Nerval-neuroendokriner Komplex ; Zollinger-Ellison-Syndrom ; Magenschleimhaut ; Elektronenmikroskopie ; Key words Nerve fibre-neuroendocrine cell complex ; Stomach ; Zollinger-Ellison-Syndrom ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary Nerve fibre-neuroendocrine cell complexes (NF-NEC-C's) are neuroendocrine cells located in the lamina propria of the gastrointestinal tract directly connected with nerve fibres of Meissner's plexus. We report on a patient with sporadic Zollinger-Ellison syndrome (ZES) with electron microscopically demonstrated multiple NF-NEC-C's in non-antral gastric mucosa. It is suspected that in ZES the hypergastrinaemia may represent a trophic stimulus for the proliferation of NF-NEC-C's in the gastric mucosa.
    Notizen: Zusammenfassung Unter nerval-neuroendokrinen Komplexen (N-NE-K) versteht man in der Lamina propria mucosae des Magen-Darm-Traktes gelegene Nester neuroendokriner Zellen, die in direktem Kontakt zu Nervenfasern des Meissner-Plexus stehen. Es wird über einen Patienten mit sporadischem Zollinger-Ellison-Syndrom (ZES) berichtet, bei dem sich elektronenmikroskopisch in nonantraler Magenschleimhaut multiple N-NE-K fanden. Möglicherweise stellt die Hypergastrinämie bei ZES einen trophischen Stimulus für die Proliferation von N-NE-K in der Magenschleimhaut dar.
    Materialart: Digitale Medien
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 163 (1995), S. 300-306 
    ISSN: 1432-072X
    Schlagwort(e): Nitrosomonas europea ; Hydroxylamine oxidoreductase (HAO) ; Electron microscopy ; Electron spectroscopic imaging ; Quaternary structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The hydroxylamine oxidoreductase from Nitrosomonas europaea was prepared to apparent electrophoretic homogeneity. Electron microscopy of negatively stained preparations of the sample revealed an overall diameter of about 8.8 nm of the enzyme particle. The native structure was determined as a tetrahedron-like assembly of identical subunits exhibiting four protein masses.
    Materialart: Digitale Medien
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Archives of microbiology 163 (1995), S. 300-306 
    ISSN: 1432-072X
    Schlagwort(e): Key wordsNitrosomonas europea ; Hydroxylamine ; oxidoreductase (HAO) ; Electron microscopy ; Electron ; spectroscopic imaging ; Quaternary structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The hydroxylamine oxidoreductase from Nitrosomonas europaea was prepared to apparent electrophoretic homogeneity. Electron microscopy of negatively stained preparations of the sample revealed an overall diameter of about 8.8 nm of the enzyme particle. The native structure was determined as a tetrahedron-like assembly of identical subunits exhibiting four protein masses.
    Materialart: Digitale Medien
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  • 23
    ISSN: 1432-1173
    Schlagwort(e): Schlüsselwörter Morbus Hailey-Hailey ; Pemphigus chronicus benignus familiaris ; Polymerasekettenreaktion ; Herpes-simplex-Virus ; Elektronenmikroskopie ; Histologie ; Key words Hailey-Hailey disease ; Benign familial pemphigus ; Polymerase chain reaction ; Herpes simplex virus ; Electron microscopy ; Histology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary A 49-year-old man suffered from Hailey-Hailey disease for several years. The patient presented with an acute exacerbation of the disease, which did not respond to oral treatment with high doses of glucocorticosteroids. A skin biopsy was taken and the histological examination indicated a viral infection. Herpes simplex virus was confirmed by electron microscopy (negative staining) and polymerase chain reaction (PCR). The PCR presents a sensitive and effective molecular-biological method for the diagnosis of viral infections.
    Notizen: Zusammenfassung Es wird über einen 49jährigen Patienten berichtet, bei dem seit Jahren ein Morbus Hailey-Hailey bekannt ist. Bei einem Rezidiv der Erkrankung kam es trotz hoher Glukokortikosteroidgaben zu keiner Remission. Erst die erneute diagnostische Abklärung des Rezidivs durch eine Hautprobe ergab den Verdacht auf eine Herpessimplex-Virus-Infektion, die über elektronenmikroskopische Negativkontrastierung und über Polymerasekettenreaktion (PCR) bestätigt werden konnte. Anhand dieser Kasuistik wird auf ein neueres molekularbiologisches Verfahren hingewiesen, das eine sensitive und schnelle Methode zum Virusnachweis darstellt.
    Materialart: Digitale Medien
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  • 24
    ISSN: 1432-2307
    Schlagwort(e): Adult Niemann-Pick disease ; Generalized AL-amyloidosis ; Progressive liver failure ; Fibroblast culture ; Immunohistochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We report a case in which an adult form of Niemann-Pick disease (type B of NPD) was associated with a rapidly progressive generalized AL amyloidosis of kappa type. Both diagnosis were made by biopsy, the NPD by bone marrow biopsy and fibroblast culture, the amyloidosis by liver biopsy. Malignant non-Hodgkin lymphoma was not found. The patient, a 67-year-old woman, died from hepatic coma subsequent to a progressive liver failure. We discuss possible relations between the lysosomal storage disease and the development and rapid progression of amyloidosis.
    Materialart: Digitale Medien
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  • 25
    ISSN: 1432-0878
    Schlagwort(e): Key words: Node of Ranvier ; Axon ; Horseradish peroxidase (HRP) ; Retrograde axonal transport ; Electron microscopy ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Horseradish peroxidase (HRP) was injected into the left dorsal column nuclei of adult cats. Large dorsal funiculi axons of the C3, C5, C8 and L7 segments were searched for HRP-activity after 12, 24, 36 and 48 h using light and electron microscopy. Accumulations of intra-axonal HRP-positive bodies occurred at nodes of Ranvier in the C3–C8 segments at 12, 24 and 36 h and in the L7 segments at 24, 36, and 48 h. The accumulations of HRP in three spatio-temporally different consecutive patterns, noted earlier at nodes of Ranvier in the peripheral nervous system (PNS) portion of feline alpha motor axons for more than 70 h after an intramuscular injection of the enzyme, were not observed in the present material. We suggest that the differences in the modes in which large PNS and CNS axons interact with retrogradely transported HRP are due to differences in the organization of the respective nodal regions. We also emphasize that endocytosis via axon terminals in the CNS normally represents uptake of material from an extracellular space which is controlled and protected by the blood-brain barrier. This is in contrast to endocytosis via axon terminals in a muscle, which represents uptake of material from an extracellular space openly exposed to influx of different substances from the blood stream.
    Materialart: Digitale Medien
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  • 26
    ISSN: 1432-0878
    Schlagwort(e): Key words: Lateral heart nerve ; FMRFamide ; Allatostatin ; Coexistence ; Mirror-section ; Axosomatic synapses ; Electron microscopy ; Periplaneta americana (Insecta)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Both allatostatin immunoreactivity (AS-IR) and FMRFamide immunoreactivity (FMRFa-IR) have been demonstrated light-microscopically in the lateral heart nerve of Periplaneta americana. The identical labeling of some fibers suggests the coexistence of the two antigens. Electron-microscopically, six granule types in the peripheral part of the lateral heart nerve can be distinguished according to their size and density (types 1–6). These granule types can be subdivided immunocytochemically by means of a new mirror-section technique. Granules of types 4 and 5 always exclusively show FMRFa-IR. In the populations of fibers containing granules of types 1 and 6, axon profiles can be found that contain granules colocalizing FMRFa-IR and AS-IR. Other axon profiles of these populations only contain immunonegative granules of the same ultrastructure. Granules of type 2 can be differentiated immunocytochemically in three forms in the same section: In some fibers, they are nonreactive; in other fibers of the same section, they show FMRFa – IR, whereas in a third fiber type, granules show AS – IR. Finally, granules of type 3 can be observed with FMRFa-IR. In other fibers, they occur with the same ultrastructure but exhibit no immunoreactivity. Two soma types occur in the lateral heart nerve. Soma type I is characterized by the production of electron-dense granules that show FMRFa-IR. Type II is in close contact with various fibers, forming different types of axosomatic synapses, hitherto unknown in Insecta.
    Materialart: Digitale Medien
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  • 27
    ISSN: 1432-0878
    Schlagwort(e): Key words: Spermatozoa ; Acrosome ; Thiols ; Disulphides ; Electron microscopy ; Monomaleimido nanogold ; Macropus eugenii (Marsupialia)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. This study utilised a commercially available monomaleimido-nanogold reagent to directly label cellular thiol groups (SH) of marsupial (tammar wallaby) spermatozoa before and after reduction of disulphides (S-S) with mercaptoethylamine hydrochloride (MEA). The sperm surface, mitochondrial membranes, axoneme and tail fibres were all labelled with gold particles before MEA treatment and the label intensity was increased after S-S reduction. The acrosomal membranes and matrix of spermatozoa contained no detectable SH prior to MEA treatment. However, after moderate MEA treatment (1 mg/ml) gold label was associated with the acrosomal membrane and invaginated acrosomal membrane within the acrosomal matrix. After exposure to 5 and 10 mg/ml MEA, gold particles heavily labelled the acrosomal matrix. Thus, the acrosomal membranes and matrix of tammar wallaby spermatozoa both contain S-S cross-linked structures, and this may contribute to the unusual stability of the marsupial acrosome. Under all treatment conditions the nucleus remained unlabelled. This is consistent with early studies which indicated that cysteine was absent from the nuclear protamines. The study also demonstrated that monomaleimido-nanogold can be used to resolve SH- and S-S-rich cellular structures directly, in addition to its use to label antibodies and Fab fragments for immunochemical localisation.
    Materialart: Digitale Medien
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  • 28
    ISSN: 1432-0878
    Schlagwort(e): Somatotrophs ; Growth hormone ; Growth hormone-releasing factor ; Secretory granule ; Electron microscopy ; Morphometry ; Rat (Fischer 344)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The anterior pituitary tissue of male rats injected with growth hormone-releasing factor (GRF) was either processed for stereology at the light-and electron-microscopic levels, or homogenized for growth hormone (GH) assay 2–60 min after GRF injection. Secretory granules of somatotrophs became smaller but increased in numerical density 2 min after GRF injection. Their volume density began to increase at 5 min. The frequency of exocytosis of the granules was most prominent as early as 2 min after GRF injection and reduced thereafter. GH levels in the tissue were lowest at 2–5 min, and returned to the control value by 60 min. Serum GH levels were highest at 15 min; even at 60 min, this value was higher than in the controls. These findings suggest that secretory granules in somatotrophs are stimulated to divide by GRF, resulting in a decrease in size and an increase in number. The discrepancy between the earlier formation of new secretory granules and the later restoration of intracellular GH levels implies that GRF first stimulates the synthesis of constituents of granules other than GH, and only later the synthesis of GH, and that newly formed small secretory granules contain less GH. From the clearance rate of serum GH and the frequency of granule exocytosis, it can be estimated that about a half million granules are released to maintain 1 ng/ml of serum GH in rats.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 280 (1995), S. 183-188 
    ISSN: 1432-0878
    Schlagwort(e): Blood platelets ; Oxidized LDL ; Cytochalasin D ; Reflection contrast microscopy ; Image analysis ; Electron microscopy ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The adhesion of human blood platelets is studied with an in vitro model using reflection contrast microscopy and an image analysis system. The adhesive feature is promoted by oxidatively modified low density lipoprotein, which also induces functional morphological changes of platelets. However, when washed platelets are pretreated with 0.05 mM cytochalasin D, oxidized low density lipoprotein (100 μg/ml) causes a slower increase of the adhesion area (11.6 μm2/min) compared to untreated platelets (15.7 μm2/min) or platelets treated by oxidized low density lipoprotein alone (20.5 μm2/min, P〈0.01). These results are supported by light transmission analysis and by transmission electron microscopy. Our experiments suggest that cytochalasin D inhibits the change of platelets in shape induced by oxidized low density lipoprotein, hinders the adhesion, but does not prevent the adhesion entirely.
    Materialart: Digitale Medien
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  • 30
    ISSN: 1432-0878
    Schlagwort(e): Nitric oxide synthase ; Vasoactive intestinal peptide ; Immunohistochemistry ; Electron microscopy ; Submucous plexus ; Guinea-pig
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract In the submucous plexus of the guinea-pig ileum, previous light-microscopic studies have revealed that vasoactive intestinal peptide (VIP)-immunoreactive and nitric oxide synthase (NOS)-immunoreactive terminals are found predominantly in association with VIP-immunoreactive nerve cell bodies. In this study, double-label immunohistochemistry at the light-microscopic level demonstrated co-localization of NOS-immunoreactivity and VIP-immunoreactivity in axon terminals in submucous ganglia. About 90% of nerve fibres with NOS-immunoreactivity or VIP-immunoreactivity were immunoreactive for both antigens; only about 10% of labelled varicosities contained only NOS-immunoreactivity or VIP-immunoreactivity. The VIP/NOS varicosities were more often seen in the central parts of the ganglia, close to the VIP-immunoreactive cell bodies. Ultrastructural immunocytochemistry with antibodies to VIP was used to determine if NOS/VIP terminals synapse exclusively with VIP-immunoreactive nerve cell bodies. We examined the targets of VIP-immunoreactive boutons in two submucous ganglia from different animals. Serial ultrathin sections were taken through the ganglia after they had been processed for VIP immunocytochemistry. For each cell body, the number of VIP inputs (synapses and close contacts) was determined. The number of VIP-immunoreactive synapses received by the cell bodies of submucous neurons varied from 0–4 and the number of VIP-immunoreactive close contacts varied from 3–10. There was no significant difference between VIP-immunoreactive nerve cell bodies and non-VIP nerve cell bodies in the number of VIP-immunoreactive synapses and close contacts they received. Thus, the implication from light microscopy that NOS/VIP terminals end predominantly on VIP nerve cells was not vindicated by electron microscopy.
    Materialart: Digitale Medien
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  • 31
    ISSN: 1432-0878
    Schlagwort(e): CD44, adhesion molecule ; Bone ; Osteoclasts ; Osteocytes ; Immunohistochemistry ; Confocal laser scanning microscopy ; Electron microscopy ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract CD44 is a multifunctional adhesion molecule that binds to hyaluronic acid, type I collagen, and fibronectin. We have studied the immunohistochemical localization of CD44 in bone cells by confocal laser scanning microscopy and transmission electron microscopy in order to clarify its role in the cell-cell and/or cell-matrix interaction of bone cells. In round osteoblasts attached to bone surfaces, immunoreactivity is restricted to their cytoplasmic processes. On the other hand, osteocytes in bone matrices show intense immunoreactivity on their plasma membrane. Intense immunoreactivity for CD44 can be detected on the basolateral plasma membranes of osteoclasts. There is considerably less reactivity observed in the area of the plasma membrane that is in direct contact with bone. The pre-embedding electron-microscopical method has revealed that CD44 is mainly localized on the basolateral plasma membrane of osteoclasts. However, the ruffled border and clear zone show little immunoreactivity. A CD44-positive reaction can be detected on both plasma membranes in the contact region between osteoclasts and osteocytes. These findings suggest that: 1) cells of the osteoblast lineage express CD44 in accordance with their morphological changes from osteoblasts into osteocytes; 2) osteoclasts express CD44 on their basolateral plasma membrane; 3) CD44 in osteoclasts and osteocytes may play an important role in cell-cell and/or cell-matrix attachment via extracellular matrices.
    Materialart: Digitale Medien
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  • 32
    ISSN: 1432-0878
    Schlagwort(e): Nitric oxide synthase ; Coronary vasculature ; Electron microscopy ; Immunocytochemistry Rat (sprague Dawley) ; Guinea-pig (Dunkin Hartley)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Ultrastructural investigation of nitrix oxide synthase-immunoreactive nerves closely associated with blood vessels in rat and guinea-pig hearts revealed many labelled nerve fibres in the walls of the main branches of the coronary arteries, and in arterioles, capillaries and post-capillary venules. The number of nitric oxide synthase-containing nerve fibres associated with different vessels, even those of the same calibre, varied. Terminal regions of nitric oxide synthase-immunoreactive fibres were observed in the endocardium and myocardium. Nitric oxide synthase-labelled fibres displayed electrondense immunoproduct in both varicose and intervaricose regions. Immunoreactive axonal varicosities contained both small and large synaptic vesicles. The characteristics of the nitric oxide synthase-immunoreactive nerve fibres observed in the heart and the possibility that these fibres represent the processes of intracardiac neurones and/or sensory neurones of extrinsic origin are discussed.
    Materialart: Digitale Medien
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  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 281 (1995), S. 69-76 
    ISSN: 1432-0878
    Schlagwort(e): Periodic lamellar granule ; Primary granule ; Chronic myeloproliferative disorder ; Neutrophils ; Electron microscopy ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Granules consisting of periodically arranged membranous lamellae and amorphous electron-opaque material, i.e., periodic lamellar granules, are present in human neutrophils. To date, no extensive ultrastructural studies have been carried out on these granules because of their infrequent presence in neutrophils. The bone marrow of 18 cases of chronic myeloproliferative disorders, including one case of chronic neutrophilic leukemia in which periodic lamellar granules were frequently seen in neutrophils, was investigated by electron microscopy. Periodic lamellar granules were seen in neutrophils in 12 of the 18 cases at varying frequencies. They were preferentially seen in immature neutrophils. The transverse profiles of these granules revealed concentric complete/incomplete rings or periodic parallel straight lines, i.e., various patterns of lamellar arrangement were present. Periodic lamellar granules were positive for myeloperoxidase and lysozyme at the electron-microscopic level. These results suggest that these granules represent a primary neutrophil granule subtype. However, their functional and pathologic significance remains unknown.
    Materialart: Digitale Medien
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  • 34
    ISSN: 1432-0878
    Schlagwort(e): Key words: Ellipsoids ; Spleen ; Electron microscopy ; Fluorescent microspheres ; Oncorhynchus mykiss (Teleostei)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. The ultrastructure of ellipsoids in the spleen of rainbow trout (Oncorhynchus mykiss) is described. The endothelium of terminations of arterioles bulged into the lumen, and gaps between the endothelial cells were evident. A continuous basal lamina was not present, and there were extensive interdigitations between the endothelial cells and surrounding reticular cells. The interdigitating processes were rich in microfilaments. Intravenously injected colloidal carbon, approximately 0.03 μm in diameter, was held in the reticular matrix of the ellipsoidal wall and taken up by macrophages that extended cellular processes among the reticular and endothelial cells. The intravenous injection of fluorescent polystyrene microspheres of known diameter showed that microspheres with a diameter of 0.5 or 1.0 μm were localised in the red pulp, whereas microspheres with a diameter of 0.15 μm were retained in ellipsoidal walls. Thus, the terminations of splenic arterioles in rainbow trout were found to be consistent with descriptions of ellipsoids in other vertebrates in that they possessed a specialised cuboidal endothelium, lacked a continuous basal lamina, were surrounded by a sheath of macrophages and reticular cells, and had a role in the selective filtration and retention of blood-borne particles.
    Materialart: Digitale Medien
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  • 35
    ISSN: 1432-0878
    Schlagwort(e): Lateral heart nerve ; FMRFamide ; Allatostatin ; Coexistence ; Mirror-section ; Axosomatic synapses ; Electron microscopy ; Periplaneta americana (Insecta)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Both allatostatin immunoreactivity (AS-IR) and FMRFamide immunoreactivity (FMRFa-IR) have been demonstrated light-microscopically in the lateral heart nerve of Periplaneta americana. The identifical labeling of some fibers suggests the coexistence of the two antigens. Electron-microscopically, six granule types in the peripheral part of the lateral heart nerve can be distinguished according to their size and density (types 1–6). These granule types can be subdivided immunocytochemically by means of a new mirror-section technique. Granules of types 4 and 5 always exclusively show FMRFa-IR. In the populations of fibers containing granules of types 1 and 6, axon profiles can be found that contain granules colocalizing FMRFa-IR and AS-IR. Other axon profiles of these populations only contain immunonegative granules of the same ultrastructure. Granules of type 2 can be differentiated immunocytochemically in three forms in the same section: In some fibers, they are nonreactive; in other fibers of the same section, they show FMRFa-IR, whereas in a third fiber type, granules show AS-IR. Finally, granules of type 3 can be observed with FMRFA-IR. In other fibers, they occur with the same ultrastructure but exhibit no immunoreactivity. Two soma types occur in the lateral heart nerve. Soma type I is characterized by the production of electron-dense granules that show FMRFa-IR. Type II is in close contact with various fibers, forming different types of axosomatic synapses, hitherto unknown in Insecta.
    Materialart: Digitale Medien
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  • 36
    ISSN: 1432-0878
    Schlagwort(e): Suprachiasmatic nucleus ; Catecholamines ; Dopamine ; Electron microscopy ; Vasoactive intestinal peptide ; Vasopressin ; Rat (Sprague Dawley)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Catecholaminergic fibers in the suprachiasmatic nucleus of adult rats were investigated by use of light- and electron-microscopic immunocytochemistry. The suprachiasmatic nucleus receives a modest density of tyrosine hydroxylase-containing axons, homogeneously distributed in the nucleus and forming varicosities throughout its entire rostro-caudal extension. Immunolabeling with antibodies against dopamine showed that this catecholamine input comprises a dopaminergic component. Many tyrosine hydroxylase-positive cells were localized at the immediate periphery of the suprachiasmatic nucleus. With electron-microscopic examination, dendrites of these neurons were found within the limits of the nucleus as well as at a border zone between the suprachiasmatic nucleus proper and the optic tract where they received unlabeled synapses, providing a morphological support for a possible role of dopaminergic neurons in the integration and/or transfer of light-related signals. More than 91% of catecholaminergic axonal varicosities were found to establish morphologically defined synapses with dendrites. To investigate whether these synapses might be shared with neurons of one or both of the two main peptidergic populations of the nucleus, namely vasoactive intestinal peptide- and vasopressin-containing neurons, we carried out doublelabeling experments combining immunoperoxidase and immunogold-silver labeling. Results showed only a few cases of direct association of the catecholaminergic terminals with these peptidergic categories. In both types of dually stained sections, catecholaminergic synapses were preferentially made with unlabeled dendrites. The homogeneous distribution of tyrosine hydroxylase-immunoreactive fibers in the suprachiasmatic nucleus could therefore reflect a lack of significant catecholaminergic innervation of both vasoactive intestinal peptide- and vasopressin-synthesizing neurons.
    Materialart: Digitale Medien
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  • 37
    ISSN: 1432-0878
    Schlagwort(e): Pituitary ; Gonadotrops ; Crinophagy ; Electron microscopy ; Enzyme cytochemistry ; Immunocytochemistry ; Autoradiography ; Catfish, Clarias gariepinus (Teleostei)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The possible function of globules and irregular membrane-bound masses in the gonadotropin cells of the pituitary of Clarias gariepinus was studied. Strong secretory stimulation led to the disappearance of the secretory granules from gonadotropin cells but globules and irregular masses remained present. Acid phosphatase was detected enzyme-cytochemically in both globules and irregular masses. Radiolabelling with tritiated amino acids followed by autoradiography demonstrated that globules received radioactive material after secretory granules. The latter received radioactive material within 75 min of administration of radioactive amino acids but globules and irregular masses did not. Although some globules became radioactively labelled within 24 h of the administration of radioactive amino acids, irregular masses remained unlabelled during this period. Secretory granules reacted positively with antisera against α and β gonadotropin subunits, whereas globules and irregular masses only reacted with the antiserum against the β subunit. A moderate anti-7B2 immunoreactivity was demonstrated in secretory granules and globules, whereas irregular masses labelled strongly. The combined cytological results indicate that globules and irregular masses are degradative, possibly crinophagic structures which develop by fusional events from secretory granules to globules and then to irregular masses.
    Materialart: Digitale Medien
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  • 38
    ISSN: 1432-0878
    Schlagwort(e): Key words: Pituitary ; Gonadotrops ; Crinophagy ; Electron microscopy ; Enzyme cytochemistry ; Immunocytochemistry ; Autoradiography ; Catfish ; Clarias gariepinus (Teleostei)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. The possible function of globules and irregular membrane-bound masses in the gonadotropin cells of the pituitary of Clarias gariepinus was studied. Strong secretory stimulation led to the disappearance of the secretory granules from gonadotropin cells but globules and irregular masses remained present. Acid phosphatase was detected enzyme-cytochemically in both globules and irregular masses. Radiolabelling with tritiated amino acids followed by autoradiography demons trated that globules received radioactive material after secretory granules. The latter received radioactive material within 75 min of administration of radioactive amino acids but globules and irregular masses did not. Although some globules became radioactively labelled within 24 h of the administration of radioactive amino acids, irregular masses remained unlabelled during this period. Secretory granules reacted positively with antisera against α and β gonadotropin subunits, whereas globules and irregular masses only reacted with the antiserum against the β subunit. A moderate anti-7B2 immunoreactivity was demonstrated in secretory granules and globules, whereas irregular masses labelled strongly. The combined cytological results indicate that globules and irregular masses are degradative, possibly crinophagic structures which develop by fusional events from secretory granules to globules and then to irregular masses.
    Materialart: Digitale Medien
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  • 39
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 280 (1995), S. 183-188 
    ISSN: 1432-0878
    Schlagwort(e): Key words: Blood platelets ; Oxidized LDL ; Cytochalasin D ; Reflection contrast microscopy ; Image analysis ; Electron microscopy ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. The adhesion of human blood platelets is studied with an in vitro model using reflection contrast microscopy and an image analysis system. The adhesive feature is promoted by oxidatively modified low density lipoprotein, which also induces functional morphological changes of platelets. However, when washed platelets are pretreated with 0.05 mM cytochalasin D, oxidized low density lipoprotein (100 μg/ml) causes a slower increase of the adhesion area (11.6 μm2/min) compared to untreated platelets (15.7 μm2/min) or platelets treated by oxidized low density lipoprotein alone (20.5 μm2/min, P〈0.01). These results are supported by light transmission analysis and by transmission electron microscopy. Our experiments suggest that cytochalasin D inhibits the change of platelets in shape induced by oxidized low density lipoprotein, hinders the adhesion, but does not prevent the adhesion entirely.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 40
    ISSN: 1432-0878
    Schlagwort(e): Key words: Suprachiasmatic nucleus ; Catecholamines ; Dopamine ; Electron microscopy ; Vasoactive intestinal peptide ; Vasopressin ; Rat (Sprague Dawley)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Catecholaminergic fibers in the suprachiasmatic nucleus of adult rats were investigated by use of light- and electron-microscopic immunocytochemistry. The suprachiasmatic nucleus receives a modest density of tyrosine hydroxylase-containing axons, homogeneously distributed in the nucleus and forming varicosities throughout its entire rostro-caudal extension. Immunolabeling with antibodies against dopamine showed that this catecholamine input comprises a dopaminergic component. Many tyrosine hydroxylase-positive cells were localized at the immediate periphery of the suprachiasmatic nucleus. With electron-microscopic examination, dendrites of these neurons were found within the limits of the nucleus as well as at a border zone between the suprachiasmatic nucleus proper and the optic tract where they received unlabeled synapses, providing a morphological support for a possible role of dopaminergic neurons in the integration and/or transfer of light-related signals. More than 91% of catecholaminergic axonal varicosities were found to establish morphologically defined synapses with dendrites. To investigate whether these synapses might be shared with neurons of one or both of the two main peptidergic populations of the nucleus, namely vasoactive intestinal peptide- and vasopressin-containing neurons, we carried out double-labeling experiments combining immunoperoxidase and immunogold-silver labeling. Results showed only a few cases of direct association of the catecholaminergic termin als with these peptidergic categories. In both types of dually stained sections, catecholaminergic synapses were preferentially made with unlabeled dendrites. The homogeneous distribution of tyrosine hydroxylase-immunoreactive fibers in the suprachiasmatic nucleus could therefore reflect a lack of significant catecholaminergic innervation of both vasoactive intestinal peptide- and vasopressin-synthesizing neurons.
    Materialart: Digitale Medien
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  • 41
    ISSN: 1432-0878
    Schlagwort(e): Key words: Thyro-parathyroidectomy ; Parathyroidectomy ; Enamel formation ; Light microscopy ; Electron microscopy ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. The effects of thyro-parathyroidectomy, parathyroidectomy or thyroidectomy upon enamel formation in the rat incisor were studied. One control group and four groups of surgically treated rats were used: parathyroid autotransplanted, thyroidectomized, parathyroidectomized, and thyro-parathyroidectomized. One month after surgery, the incisors were processed for light and electron microscopy. The present study revealed perturbations of the Tomes’ process morphology, of the rod pattern in the inner enamel formation, of the enamel surface, and of the mineralization after thyro-parathyroidectomy. After parathyroidectomy, only mineralization defects could be visualised. No effects were observed in enamel after thyroidectomy. A severe hypocalcemic state as seen in thyro-parathyroidectomized rats affects the enamel shape, and mineralization, and the morphology and function of secretory ameloblasts. Knowledge of the way in which the alteration of the enamel surface is produced should contribute to a better understanding of the development of tooth enamel.
    Materialart: Digitale Medien
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  • 42
    ISSN: 1432-0878
    Schlagwort(e): Meninges ; Cerebrospinal fluid ; Electron microscopy ; Aging ; Multilamellar bodies ; Surfactant ; Goldfish ; Carassius auratus (Teleostei)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract In the optic tectum of goldfish, the outer, middle and inner layers of the endomeninx were evident in animals ranging in age from 1 month to several years. The outer layer in young animals consisted of closely overlapping cells with intertwined processes, whereas in the older animals it contained large extracellular spaces. The intermediate layer cells were always arranged in a single continuous layer, but in young animals they overlapped extensively with one another toward their edges whereas in the oldest animals they became extremely flat and non-overlapping. The inner layer included an outer tier of cells with their bases adhering to the intermediate layer, and an inner tier of cells detached from both the intermediate layer and the basal lamina overlying the brain parenchyma. Inner layer cells contained many large vacuoles that were in continuity with the extracellular space. With age, the extracellular space and the vacuolar system expanded, and the inner layer evolved into a meshwork of attenuated cytoplasmic processes embedded in the granular extracellular matrix. Another age-related feature was the accumulation adjacent to the basal lamina of uniform disc-shaped membranous structures, resembling multilamellar bodies of lung surfactant. These “disc bodies” were apparently generated by the coalescence of vesicles formed at the surface of the inner layer cells, possibly as a by-product of protein secretion by these cells.
    Materialart: Digitale Medien
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  • 43
    ISSN: 1432-0878
    Schlagwort(e): Key words: Nitric oxide synthase ; Vasoactive intestinal peptide ; Immunohistochemistry ; Electron microscopy ; Submucous plexus ; Guinea-pig
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. In the submucous plexus of the guinea-pig ileum, previous light-microscopic studies have revealed that vasoactive intestinal peptide (VIP)-immunoreactive and nitric oxide synthase (NOS)-immunoreactive terminals are found predominantly in association with VIP-immunoreactive nerve cell bodies. In this study, double-label immunohistochemistry at the light-microscopic level demonstrated co-localization of NOS-immunoreactivity and VIP-immunoreactivity in axon terminals in submucous ganglia. About 90% of nerve fibres with NOS-immunoreactivity or VIP-immunoreactivity were immunoreactive for both antigens; only about 10% of labelled varicosities contained only NOS-immunoreactivity or VIP-immunoreactivity. The VIP/NOS varicosities were more often seen in the central parts of the ganglia, close to the VIP-immunoreactive cell bodies. Ultrastructural immunocytochemistry with antibodies to VIP was used to determine if NOS/VIP terminals synapse exclusively with VIP-immunoreactive nerve cell bodies. We examined the targets of VIP-immunoreactive boutons in two submucous ganglia from different animals. Serial ultrathin sections were taken through the ganglia after they had been processed for VIP immunocytochemistry. For each cell body, the number of VIP inputs (synapses and close contacts) was determined. The number of VIP-immunoreactive synapses received by the cell bodies of submucous neurons varied from 0–4 and the number of VIP-immunoreactive close contacts varied from 3–10. There was no significant difference between VIP-immunoreactive nerve cell bodies and non-VIP nerve cell bodies in the number of VIP-immunoreactive synapses and close contacts they received. Thus, the implication from light microscopy that NOS/VIP terminals end predominantly on VIP nerve cells was not vindicated by electron microscopy.
    Materialart: Digitale Medien
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  • 44
    ISSN: 1432-0878
    Schlagwort(e): Key words: CD44 ; adhesion molecule ; Bone ; Osteoclasts ; Osteocytes ; Immunohistochemistry ; Confocal laser scanning microscopy ; Electron microscopy ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. CD44 is a multifunctional adhesion molecule that binds to hyaluronic acid, type I collagen, and fibronectin. We have studied the immunohistochemical localization of CD44 in bone cells by confocal laser scanning microscopy and transmission electron microscopy in order to clarify its role in the cell-cell and/or cell-matrix interaction of bone cells. In round osteoblasts attached to bone surfaces, immunoreactivity is restricted to their cytoplasmic processes. On the other hand, osteocytes in bone matrices show intense immunoreactivity on their plasma membrane. Intense immunoreactivity for CD44 can be detected on the basolateral plasma membranes of osteoclasts. There is considerably less reactivity observed in the area of the plasma membrane that is in direct contact with bone. The pre-embedding electron-microscopical method has revealed that CD44 is mainly localized on the basolateral plasma membrane of osteoclasts. However, the ruffled border and clear zone show little immunoreactivity. A CD44-positive reaction can be detected on both plasma membranes in the contact region between osteoclasts and osteocytes. These findings suggest that: 1) cells of the osteoblast lineage express CD44 in accordance with their morphological changes from osteoblasts into osteocytes; 2) osteoclasts express CD44 on their basolateral plasma membrane; 3) CD44 in osteoclasts and osteocytes may play an important role in cell-cell and/or cell-matrix attachment via extracellular matrices.
    Materialart: Digitale Medien
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  • 45
    ISSN: 1432-0878
    Schlagwort(e): Key words: Nitric oxide synthase ; Coronary vasculature ; Electron microscopy ; Immunocytochemistry ; Rat (Sprague Dawley) ; Guinea-pig (Dunkin Hartley)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Ultrastructural investigation of nitric oxide synthase-immunoreactive nerves closely associated with blood vessels in rat and guinea-pig hearts revealed many labelled nerve fibres in the walls of the main branches of the coronary arteries, and in arterioles, capillaries and post-capillary venules. The number of nitric oxide synthase-containing nerve fibres associated with different vessels, even those of the same calibre, varied. Terminal regions of nitric oxide synthase-immunoreactive fibres were observed in the endocardium and myocardium. Nitric oxide synthase-labelled fibres displayed electron-dense immunoproduct in both varicose and intervaricose regions. Immunoreactive axonal varicosities contained both small and large synaptic vesicles. The characteristics of the nitric oxide synthase-immunoreactive nerve fibres observed in the heart and the possibility that these fibres represent the processes of intracardiac neurones and/or sensory neurones of extrinsic origin are discussed.
    Materialart: Digitale Medien
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  • 46
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 281 (1995), S. 69-76 
    ISSN: 1432-0878
    Schlagwort(e): Key words: Periodic lamellar granule ; Primary granule ; Chronic myeloproliferative disorder ; Neutrophils ; Electron microscopy ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Granules consisting of periodically arranged membranous lamellae and amorphous electron-opaque material, i.e., periodic lamellar granules, are present in human neutrophils. To date, no extensive ultrastructural studies have been carried out on these granules because of their infrequent presence in neutrophils. The bone marrow of 18 cases of chronic myeloproliferative disorders, including one case of chronic neutrophilic leukemia in which periodic lamellar granules were frequently seen in neutrophils, was investigated by electron microscopy. Periodic lamellar granules were seen in neutrophils in 12 of the 18 cases at varying frequencies. They were preferentially seen in immature neutrophils. The transverse profiles of these granules revealed concentric complete/incomplete rings or periodic parallel straight lines, i.e., various patterns of lamellar arrangement were present. Periodic lamellar granules were positive for myeloperoxidase and lysozyme at the electron-microscopic level. These results suggest that these granules represent a primary neutrophil granule subtype. However, their functional and pathologic significance remains unknown.
    Materialart: Digitale Medien
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  • 47
    ISSN: 1432-0878
    Schlagwort(e): Key words: Blood platelets ; Immunocytochemistry ; Electron microscopy ; Coated vesicles ; Clathrin ; Adhesive proteins ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. Coated membranes and vesicles play an important role in receptor-mediated endocytosis and intracellular trafficking in various cell types, and are also present in blood platelets. Platelets take up certain proteins from the blood plasma, such as von Willebrand factor and fibrinogen, and these substances are transferred to storage granules. The receptors for these plasma proteins on the platelet plasma membrane have been well characterized, but morphological evidence for their transport to the storage granules is not yet available. In an attempt to clarify this aspect, we employed postembedding immunocytochemistry on platelets embedded in the acrylic resin LR White. Clathrin as the major coat component of coated vesicles was localized in the cytoplasm, on the plasmic faces of α-granules and the open canalicular system, and on the plasmic face of the plasma membrane. Colocalizations of the adhesive proteins, von Willebrand factor, fibrinogen and fibronectin, with clathrin could be observed at the same typical locations as coated vesicles were seen in Araldite-embedded material. These colocalizations have not been reported to date and furnish further evidence for a coated vesicle-mediated transport of blood plasma-derived adhesive proteins from their receptors on the outer plasma membrane to the α-granules.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 48
    ISSN: 1432-0878
    Schlagwort(e): Key words: Meninges ; Cerebrospinal fluid ; Electron microscopy ; Aging ; Multilamellar bodies ; Surfactant ; Goldfish ; Carassius auratus (Teleostei)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. In the optic tectum of goldfish, the outer, middle and inner layers of the endomeninx were evident in animals ranging in age from 1 month to several years. The outer layer in young animals consisted of closely overlapping cells with intertwined processes, whereas in the older animals it contained large extracellular spaces. The intermediate layer cells were always arranged in a single continuous layer, but in young animals they overlapped extensively with one another toward their edges whereas in the oldest animals they became extremely flat and non-overlapping. The inner layer included an outer tier of cells with their bases adhering to the intermediate layer, and an inner tier of cells detached from both the intermediate layer and the basal lamina overlying the brain parenchyma. Inner layer cells contained many large vacuoles that were in continuity with the extracellular space. With age, the extracellular space and the vacuolar system expanded, and the inner layer evolved into a meshwork of attenuated cytoplasmic processes embedded in the granular extracellular matrix. Another age-related feature was the accumulation adjacent to the basal lamina of uniform disc-shaped membranous structures, resembling multilamellar bodies of lung surfactant. These ”disc bodies” were apparently generated by the coalescence of vesicles formed at the surface of the inner layer cells, possibly as a by-product of protein secretion by these cells.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 49
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 279 (1995), S. 445-452 
    ISSN: 1432-0878
    Schlagwort(e): Key words: Estradiol receptor ; Breast cancer cells ; Cell culture ; Ultrastructure ; Electron microscopy ; Immunohistochemistry ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. The distribution of estradiol receptor in serial sections of estradiol-deprived and estradiol-stimulated MCF7 cells was studied by using mouse monoclonal antibodies reacting with different domains of the receptor and goat-antimouse IgG/6 nm gold. In the nucleus and the cytoplasm of estradiol-deprived cells, the receptor was detected by all three monoclonals (13H2, HT 65 and MA1-310). The antibodies 13H2 and MA1-310 detected receptor associated to the microfilament bundles in the cytoplasm. Higher densities of antireceptor attachment to the nuclear areas were accompanied by a reduction in the attachment to the cytoplasm after estradiol stimulation of the cells. The results confirm earlier observations on the presence of cytoplasmic estrogen receptor in estradiol-deprived cells and support the premise of an es- tradiol-induced translocation of this ligand-dependent transcription regulator.
    Materialart: Digitale Medien
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  • 50
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 279 (1995), S. 445-452 
    ISSN: 1432-0878
    Schlagwort(e): Estradiol receptor ; Breast cancer cells ; Cell culture ; Ultrastructure ; Electron microscopy ; Immunohistochemistry ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The distribution of estradiol receptor in serial sections of estradiol-deprived and estradiol-stimulated MCF7 cells was studied by using mouse monoclonal antibodies reacting with different domains of the receptor and goat-antimouse IgG/6 nm gold. In the nucleus and the cytoplasm of estradiol-deprived cells, the receptor was detected by all three monoclonals (13H2, HT 65 and MA1-310). The antibodies 13H2 and MA1-310 detected receptor associated to the microfilament bundles in the cytoplasm. Higher densities of antireceptor attachment to the nuclear areas were accompanied by a reduction in the attachment to the cytoplasm after estradiol stimulation of the cells. The results confirm earlier observations on the presence of cytoplasmic estrogen receptor in estradiol-deprived cells and support the premise of an estradiol-induced translocation of this ligand-dependent transcription regulator.
    Materialart: Digitale Medien
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  • 51
    ISSN: 1432-0878
    Schlagwort(e): Blood platelets ; Immunocytochemistry ; Electron microscopy ; Coated vesicles ; Clathrin ; Adhesive proteins ; Human
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Coated membranes and vesicles play an important role in receptor-mediated endocytosis and intracellular trafficking in various cell types, and are also present in blood platelets. Platelets take up certain proteins from the blood plasma, such as von Willebrand factor and fibrinogen, and these substances are transferred to storage granules. The receptors for these plasma proteins on the platelet plasma membrane have been well characterized, but morphological evidence for their transport to the storage granules is not yet available. In an attempt to clarify this aspect, we employed postembedding immunocytochemistry on platelets embedded in the acrylic resin LR White. Clathrin as the major coat component of coated vesicles was localized in the cytoplasm, on the plasmic faces of α-granules and the open canalicular system, and on the plasmic face of the plasma membrane. Colocalizations of the adhesive proteins, von Willebrand factor, fibrinogen and fibronectin, with clathrin could be observed at the same typical locations as coated vesicles were seen in Araldite-embedded material. These colocalizations have not been reported to date and furnish further evidence for a coated vesicle-mediated transport of blood plasma-derived adhesive proteins from their receptors on the outer plasma membrane to the α-granules.
    Materialart: Digitale Medien
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  • 52
    ISSN: 1432-0878
    Schlagwort(e): Ellipsoids ; Spleen ; Electron microscopy ; Fluorescent microspheres ; Oncorhynchus mykiss (Teleostei)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The ultrastructure of ellipsoids in the spleen of rainbow trout (Oncorhynchus mykiss) is described. The endothelium of terminations of arterioles bulged into the lumen, and gaps between the endothelial cells were evident. A continuous basal lamina was not present, and there were extensive interdigitations between the endothelial cells and surrounding reticular cells. The interdigitating processes were rich in microfilaments. Intravenously injected colloidal carbon, approximately 0.03 μm in diameter, was held in the reticular matrix of the ellipsoidal wall and taken up by macrophages that extended cellular processes among the reticular and endothelial cells. The intravenous injection of fluorescent polystyrene microspheres of known diameter showed that microspheres with a diameter of 0.5 or 1.0 μm were localised in the red pulp, whereas microspheres with a diameter of 0.15 μm were retained in ellipsoidal walls. Thus, the terminations of splenic arterioles in rainbow trout were found to be consistent with descriptions of ellipsoids in other vertebrates in that they possessed a speciallised cuboidal endothelium, lacked a continuous basal lamina, were surrounded by a sheath of macrophages and reticular cells, and had a sheath of macrophages and reticular cells, and had a role in the selective filtration and retention of bloodborne particles.
    Materialart: Digitale Medien
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  • 53
    ISSN: 1432-0878
    Schlagwort(e): Spermatozoa ; Acrosome ; Thiols ; Disulphides ; Electron microscopy ; Monomaleimido nanogold ; Macropus eugenii (Marsupialia)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract This study utilised a commercially available monomaleimido-nanogold reagent to directly label cellular thiol groups (SH) of marsupial (tammar wallaby) spermatozoa before and after reduction of disulphides (S-S) with mercaptoethylamine hydrochloride (MEA). The sperm surface, mitochondrial membranes, axoneme and tail fibres were all labelled with gold particles before MEA treatment and the label intensity was increased after S-S reduction. The acrosomal membranes and matrix of spermatozoa contained no detectable SH prior to MEA treatment. However, after moderate MEA treatment (1 mg/ml) gold label was associated with the acrosomal membrane and invaginated acrosomal membrane within the acrosomal matrix. After exposure to 5 and 10 mg/ml MEA, gold particles heavily labelled the acrosomal matrix. Thus, the acrosomal membranes and matrix of tammar wallaby spermatozoa both contain S-S cross-linked structures, and this may contribute to the unusual stability of the marsupial acrosome. Under all treatment conditions the nucleus remained unlabelled. This is consistent with early studies which indicated that cysteine was absent from the nuclear protamines. The study also demonstrated that monomaleimido-nanogold can be used to resolve SH- and S-S-rich cellular structures directly, in addition to its use to label antibodies and Fab fragments for immunochemical localisation.
    Materialart: Digitale Medien
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  • 54
    ISSN: 1432-0878
    Schlagwort(e): Key words: Somatotrophs ; Growth hormone ; Growth hormone-releasing factor ; Secretory granule ; Electron microscopy ; Morphometry ; Rat (Fischer 344)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract. The anterior pituitary tissue of male rats injected with growth hormone-releasing factor (GRF) was either processed for stereology at the light- and electron-microscopic levels, or homogenized for growth hormone (GH) assay 2–60 min after GRF injection. Secretory granules of somatotrophs became smaller but increased in numerical density 2 min after GRF injection. Their volume density began to increase at 5 min. The frequency of exocytosis of the granules was most prominent as early as 2 min after GRF injection and reduced thereafter. GH levels in the tissue were lowest at 2–5 min, and returned to the control value by 60 min. Serum GH levels were highest at 15 min; even at 60 min, this value was higher than in the controls. These findings suggest that secretory granules in somatotrophs are stimulated to divide by GRF, resulting in a decrease in size and an increase in number. The discrepancy between the earlier formation of new secretory granules and the later restoration of intracellular GH levels implies that GRF first stimulates the synthesis of constituents of granules other than GH, and only later the synthesis of GH, and that newly formed small secretory granules contain less GH. From the clearance rate of serum GH and the frequency of granule exocytosis, it can be estimated that about a half million granules are released to maintain 1 ng/ml of serum GH in rats.
    Materialart: Digitale Medien
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  • 55
    Digitale Medien
    Digitale Medien
    Springer
    European archives of oto-rhino-laryngology and head & neck 252 (1995), S. 239-243 
    ISSN: 1434-4726
    Schlagwort(e): Homograft auditory ossicles ; Preservative solutions ; Shelf life ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The ultrastructure of preserved ossicles at different shelf lives was compared. Homograft ossicles were harvested and preserved in 70% alcohol, 1:5000 Cialit (sodium-2-ethyl-mercuri-mercapto-benzoxazole-5-carboxylate), and buffered 4% formaldehyde at pH 7. The ultrastructure of each ossicle was studied by both scanning and transmission electron microscopy and was compared to that of fresh controls placed in 0.9 N saline solution. The results indicated clearly the superiority of 70% alcohol as a long-term preservative and 1:5000 Cialit as a short-term preservative.
    Materialart: Digitale Medien
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  • 56
    Digitale Medien
    Digitale Medien
    Springer
    European archives of oto-rhino-laryngology and head & neck 252 (1995), S. 469-474 
    ISSN: 1434-4726
    Schlagwort(e): Reinke's laryngeal edema ; Electron microscopy ; Immunohistochemistry ; Pathogenesis Neobursa
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Light microscopy of vocal cord mucosa in patients with Reinke's edema revealed highly ramified fissured spaces in the subepithelial tissue that were generally lined with flat cells. The ultrastructure of the parietal cells resembled fibroblasts whose cytoplasmic extensions overlapped in two to three layers in some places. Cell contacts were not observed. Neither electron microscopy nor immunohistochemical testing with antibody against laminin demonstrated a basal membrane. It was possible to distinguish between light and dark cells in the specimens examined. The cytoplasm of the light cells contained intermediate filaments, mitochondria, lysosomes, coated vesicles, caveolae and broad cisternae of rough endoplasmic reticulum. The dark cells were more numerous and typically exhibited a well-developed endoplasmic reticulum and free ribosomes. The parietal cells showed no immunoreaction against human vascular endothelial cells. Immunohistochemical demonstration of mesenchymal intermediate filaments using antibody against vimentin yielded a positive reaction for some of the cells in the walls of the crevices and subepithelial tissue. It was also possible to demonstrate a few cells with monoclonal antibody against macrophages (KiM6). These findings contradict the concept of lymphatic distension in cases of Reinke's edema. Since the parietal cells seen resembled synoviocytes in their structure and immunohistochemical reactions, findings indicate that the hollow spaces of Reinke's edema develop like neobursae from mechanical strain.
    Materialart: Digitale Medien
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  • 57
    Digitale Medien
    Digitale Medien
    Springer
    European archives of oto-rhino-laryngology and head & neck 252 (1995), S. 229-235 
    ISSN: 1434-4726
    Schlagwort(e): Larynx ; Neuroendocrine carcinoma ; Carcinoid tumor ; Immunohistochemistry ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Carcinoid tumors belong to the group of neuroendocrine tumors of epithelial origin, i.e., neuroendocrine carcinomas. These neoplasms usually occur in the gastrointestinal tract or bronchial system but are very rare neoplasms in the larynx. Since carcinoid tumors in this latter site may appear to be undifferentiated by light microscopy, they may possibly be misinterpreted and their neuroendocrine characteristics may remain unrecognized. Using immunohistochemical methods, three carcinoid tumors were studied and showed positive immunostaining for markers of epithelial origin (cytokeratins, epithelial membrane antigen, carcino-embryonic antigen) and, in particular, for markers of neuroendocrine differentiation (chromogranin, synaptophysin, neuron-specific enolase). All tumors expressed calcitonin-, serotonin- and adrenocorticotropic-hormone-like immunoreactivity. In contrast, three poorly differentiated squamous cell carcinomas showed positive immunostaining for epithelial markers but did not show any immunoreactivity with markers of endocrine characteristics. Fine structurally, carcinoid tumor cells contained neurosecretory-type granules scattered throughout the cytoplasm. The present study demonstrated that (1) carcinoid tumors of the larynx possess distinct immunohistochemical characteristics that allow a clear classification, (2) it is advisable to use a battery of primary antibodies rather than rely on specificity and sensitivity of a single marker to establish diagnosis and (3) the fine structural demonstration of neurosecretory-type granules serves as a reliable adjunct to diagnosis.
    Materialart: Digitale Medien
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  • 58
    Digitale Medien
    Digitale Medien
    Springer
    European archives of oto-rhino-laryngology and head & neck 252 (1995), S. 53-56 
    ISSN: 1434-4726
    Schlagwort(e): Parotid gland ; Amyloidosis ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A case of an organ-limited amyloid tumor of the left parotid gland is described with a history of recurrence. A slowly growing parotid mass was the only symptom. After 5.5 years following local excision, the patient was readmitted with a slowly growing recurrence in the superficial lobe of the previously treated gland. Lateral parotidectomy was performed with wide excision of the infiltrated tissue and preservation of the facial nerve. Primary amyloidosis of the AL type was confirmed with immunohistochemical studies revealing staining for lambda but not kappa light chains of immunoglobulins. There has been no clinical or laboratory evidence of systemic amyloidosis or recurrence after 2 years. To the best of our knowledge, this is the first report of a recurrent amyloid tumor of the parotid gland.
    Materialart: Digitale Medien
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  • 59
    Digitale Medien
    Digitale Medien
    Springer
    European archives of oto-rhino-laryngology and head & neck 252 (1995), S. 249-254 
    ISSN: 1434-4726
    Schlagwort(e): Middle ear ; Glycoconjugate ; Wheat germ agglutinin ; Electron microscopy ; Guinea pig
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract To evaluate the protective function of the mucous blanket (MB) against lectin substances, we examined at the ultrastructural level whether intraluminal colloidal gold-labelled wheat germ agglutinin (WGA) could enter the MB-covered epithelial cell surface of the guinea pig tubotympanic mucosa. Post-embedding staining with WGA/gold on thin tissue sections was done in parallel for comparison. The cell surface glycoconjugate of the eustachian tubal and transitional epithelium had a typical bilayered structure: the outer MB and the microvilli-associated glycocalyx (MAG), which were interposed by the interciliary fluid zone. In squamous epithelium of the distal middle ear, the MB adhered to the MAG, thereby forming a monolayered coat of glycoconjugates at the cell surface. In the pre-embedding staining, WGA/gold did not bind with the MB and MAG in the eustachian tube, and exclusively bound with MB in the transitional area. Direct binding was also found with MAG and the apical plasmic membrane in the squamous epithelium. These findings indicate that MAG is occluded by MB lined with the interciliary fluid zone for luminal access of lectin at the proximal lumina of the tubotympanic epithelium. It is also suggested that MB existing at two sites possesses a different WGA-binding capacity: shielding as a “dust cover” in the eustachian tube and entrapping as a “flypaper” against lectin in the transitional area of the middle ear.
    Materialart: Digitale Medien
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  • 60
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 631-638 
    ISSN: 0006-3592
    Schlagwort(e): Saccharomyces cerevisiae ; fermentation ; on-line simulation ; state estimation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: In order to study and control fermentation processes, indirect on-tine measurements and mathematical models can be used. In this article we present a mathematical on-line model for fermentation processes. The model is based on atom and partial mass balances as well as on equations describing the acid-base system. The model is brought into an adaptive form by including transport equations for mass transfer and unstructured expressions for the fermentation kinetics. The state of the process, i.e., the concentrations of biomass, substrate, and products, can be estimated on-line using the balance part of the model completed with measurement equations for the input and output flows of the process. Adaptivity is realized by means of on-line estimation of parameters in the transport and kinetic expressions using recursive regression analysis. These expressions can thus be used in the model as valid equations enabling prediction of the process. This makes model-based automation of the process and testing of the validity of the measurement variables possible. The model and the on-line principles are applied to a 3.5-L laboratory tormentor in which Saccharomyces cerevisiae is cultivated. The experimental results show that the model-based estimation of the state and the predictions of the process correlate closely with high-performance liquid chromatography (HPLC) analyses. © 1995 John Wiley & Sons, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 61
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 659-666 
    ISSN: 0006-3592
    Schlagwort(e): methanogenic activity ; ethylene ; dechlorination ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Kinetics were determined for methanogenic activity and chlorinated ethylene dehalogenation by a methanol-enriched, anaerobic sediment consortium. The culture reductively dechlorinated perchloroethylene (PCE) to trichloroethylene (TCE), 1,1-dichloroethylene (1,1-DCE), vinylchloride (VC), and ethylene and ethane. The absence : of methanol or the addition of 2-bromoethanesulfonic. acid in the presence of methanol suppressed both methanogenic activity and dechlorination. In contrast, acetate production continued in the presence of 2-bromoethanesulfonic acid. These results suggest that dechlorination was strongly linked to methane formation and not to acetate production. A kinetic model, developed to describe both methanogenesis and dechlorination, successfully predicted experimentally measured concentrations of biomass, methane, substrate, and chlorinated ethylenes. The average maximum specific dehalogenation rates for PCE, TCE, 1,1-DCE, and VC were 0.9 ± 0.6, 0.4 ± 0.1, 12 ± 0.1, and 2.5 ± 1.7 μmol contaminant/ g. DW/day, respectively. This pattern for dechlorination rates is distinctly different than that reported for transition metal cofactors, where rates drop by approximately one order of magnitude as each successive chlorine is removed. The experimental results and kinetic analysis suggest that it will be impractical to targeting methanol consuming methanogenic organisms for in situ ground-water restoration. © 1995 John Wiley & Sons, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 62
    ISSN: 0006-3592
    Schlagwort(e): bovine serum albumin ; growth factor ; hollow-fiber culture ; perfusion culture ; antibody production rate ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The effects of the high-molecular-weight growth factors, transferrin and bovine serum albumin (BSA), on antibody production were analyzed quantitatively in continuous hollow-fiber cultivation over a period of 60 days. Transferrin enhanced cell growth but had no significant effect on the specific antibody production rate, whereas BSA significantly enhanced antibody production. The antibody production rate was increased 4- and 14-fold respectively by feeding BSA at 2 and 5 g L-1 into the EC side of the system (the side connected to the cell-containing outer part of the hollow-fiber unit) compared with the production achieved without BSA. Addition of 5 g L1 BSA into the IC side of the system (the side connected to the inner part of the hollow-fiber unit) resulted in a 2.5-fold increase in the antibody production rate. The effect of BSA was also analyzed using the perfusion culture system with a separation unit. When fresh medium containing either 2 or 5 g L-1 BSA was fed into the reactor, both the specific growth rate and specific death rate increased, while the specific antibody production rate was increased 2- and 25-fold, respectively, by feeding BSA at these two concentrations compared with no addition. Comparing the two systems, the increase in the antibody production rate achieved with the hollow-fiber system was threefold greater than that in the perfusion culture system with the same concentration of BSA feeding. © 1995 John Wiley & Sons, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 63
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 132-140 
    ISSN: 0887-3585
    Schlagwort(e): protein folding ; protein stability ; mutational effects ; φ, ψ distribution ; Ramachandran map ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Changes in amino acid side chains have long been recognized to alterthe range and distribution of φ, ψ angles found in the main chain of polypeptides. Altering the range and distribution of φ, ψ angles also alters the conformational entropy of the flexible denatured state and may thus stabilize or destabilize it relative to the comparatively conformationally rigid native state. A database of 12,320 residues from 61 nonhomologous, high resolution crystal structures was examined to determine the φ, ψ conformational preferences of each of the 20 amino acids. These observed distributions in the native state of proteins are assumed to also reflect the distributions found in the denatured state. The distributionswere used to approximate the energy surface for each residue, allowing the calculation of relative conformational entropies for each residue relative to glycine. In the most extreme case, replacement of glycine by proline, conformational entropy changes will stabilize the native state relative to the denatured state by -0.82 ± 0.08 kcal/mol at 20°C. Surprisingly, alanine is found to be the most ordered residue other than proline. This unexpected result is a result of the high percentage of alanines found in helical conformations. This either indicates that the observed distributions in the native state do not reflect the distributions in the denatured state, or that alanine is much more likely to adopt a helical conformation in the denatured state than residues with longer side chains. Among those residues with φ, ψ angles compatible with helix incorporation the percentage of alanines actually in helices is very similar to other residues. This and the consistent ordering of alanine relative to other residues regardless of secondary structure are evidence that φ, ψ distributions in native states reflect those in the denatured states. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 64
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 154-167 
    ISSN: 0887-3585
    Schlagwort(e): iron-sulfur proteins ; electron transfer ; oxidation-reduction potentials ; solvent accessibility ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Molecular dynamics simulations of Clostridium pasteurianum rubredoxin in the oxidized and reduced forms have been performed. Good agreement between both forms and crystal data has been obtained (rms deviation of backbone atoms of 1.06 and 1.42 Å, respectively), which was due in part to the use of explicit solvent and counterions. The reduced form exhibits an unexpected structural change: the redox site becomes much more solvent-accessible, so that water enters a channel between the surface and the site, but with little actual structural rearrangement (the rms deviation of backbone atoms between the oxidized and reduced is 0.77 Å). The increase in solvent accessibility is also seen, although to a much lesser extent, between the oxidized and reduced crystal structures of Pyrococcus furiosus rubredoxin, but no high resolution crystal or nuclear magnetic resonance solution data exist for reduced C. pasteurianum rubredoxin. The electrostatic potential at the iron site and fluctuations in the potential, which contribute to both the redox and electron transfer properties, have also been evaluated for both the oxidized and the reduced simulations. These results show that the backbone plays a significant role (62-70 kcall/mol/e) and the polar sidechains contribute relatively little (0-4 kcal/mol/e) to the absolute electrostatic potential at the iron of rubredoxin for both forms. However, both groups contribute significantly to the change in redox state by becoming more polarized and more densely packed around the redox site upon reduction. Furthermore, these results show that the solvent becomes much more polarized in the reduced form than in the oxidized form, even excluding the penetrating water. Finally, the simulation indicates that the contribution of the charged side chains to the electrostatic potential is largely canceled by that of the counterions. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 65
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 191-192 
    ISSN: 0887-3585
    Schlagwort(e): lipopolysaccharide ; lipid A ; endotoxin ; protein structure ; acyltransferase ; X-ray crystallography ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Crystals of UDP-N-acetylglucosamine O-acyltransferase (lpxA) fromEscherichia coli have been obtained from solutions of sodium/potassium phosphate and dimethylsulfoxide. These crystals belong to the cubic space group P213 (a = 99.0 Å), diffract X-raysto approximately 2.5 Å resolution and contain one subunit of the enzyme in the asymmetric unit. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 66
    ISSN: 0887-3585
    Schlagwort(e): hydrophobic moment ; peptide-cell ; membrane interactions ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Multiple linear regression was used to quantify the dependence of the antimicrobial activity of 13 peptides upon three calculated or experimentally determined parameters: mean hydrophobicity, mean hydrophobic moment, and α-helix content. Mean hydrophobic moment is a measure of the amphiphilicity of peptides in an α-helical conformation. Antimicrobial activity was quantified as the reciprocal of the measured minimal inhibitory concentration (MIC) against Escherichia coli. One of the peptides was magainin 2, and the remainder were novel peptides designed for this study. The multiple linear regression results revealed that the amphiphilicity of the peptides was the most important factor governing anti-microbial activity compared to mean hydrophobicity orα-helix content. A better regression cf the data was obtained using In(1/MIC + constant) as the dependent variable than with either 1/MIC or In(1/MIC). These results should be useful in designing peptides with higher antimicrobial activity. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 67
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 168-181 
    ISSN: 0887-3585
    Schlagwort(e): aspartic proteinase ; enzyme kinetics ; rule-based model ; chromogenic assay ; synthetic substrate ; inhibitor ; molecular modeling ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Aspartic proteinases are produced in the human body by a variety of cells. Some of these proteins, examples of which are pepsin, gastricsin, and renin, are secreted and exert their effects in the extracellular spaces. Cathepsin D and cathepsin E on the other hand are intracellular enzymes. The least characterized of the human aspartic proteinases is cathepsin E. Presented here are results of studies designed to characterize the binding specificities in the active site of human cathepsin E with comparison to othermechanistically similar enzymes. A peptide series based on Lys-Pro-Ala-Lys-Phe*Nph-Arg-Leu was generatedto elucidate the specificity in the individual binding pockets with systematic substitutions in the P5- P2 and P2′-P3′ based on charge, hydrophobicity, and hydrogen bonding. Also, to explore the S2 binding preferences, asecond series of peptides based on Lys-Pro-Ile-Glu-Phe*Nph-Arg-Leu was generated with systematic replacements in the P2 position. Kinetic parameters were determined forboth sets of peptides. The results were correlated to a rule-based structural model of human cathepsin E, constructed on the known three-dimensional structures of several highly homologous aspartic proteinases; porcine pepsin, bovine chymosin, yeast proteinase A, human cathepsin D, andmouse and human renin. Important specificity-determining interactions were found in the S3 (Glu13) and S2 (Thr-222, Gln-287, Leu-289, Ile-300)subsites. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 68
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995) 
    ISSN: 0887-3585
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 69
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 193-196 
    ISSN: 0887-3585
    Schlagwort(e): urea cycle ; frog ; liver ; carbamyl phosphate synthetase ; X-ray diffraction ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Carbamoyl phosphate synthetase I (ammonia; E C 6.3.4.16) was purified from the liver of Rana catesbeiana (bullfrog). Crystals of the protein have been obtained at 22°C by the hanging drop vapor diffusion technique, with polyethylene glycol as precipitant. Tetragonal crystals of about 0.3 × 0.3 × 0.7 mm diffract at room temperature to at least 3.5 Å using a conventional source and are stable to X-radiation for about 12 h. Therefore, these crystals are suitablefor high resolution studies. The space group is P41212 (or its enantiomorph P43212), with unit cell dimensions a = b = 291.6 Å and c = 189.4 Å. Density packing considerations areconsistent with the presence of 4-6 monomers (Mr of the monomer, 160,000) in the asymmetric unit. Amino-terminal sequence of the enzyme and of a chymotryptic fragment of 73.7 kDa containing the COOH-terminus has been obtained. The extensive sequence identity with rat and human carbamoyl phosphate synthetase I indicates the relevance for mammals of structural data obtained with the frog enzyme. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 70
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 199-209 
    ISSN: 0887-3585
    Schlagwort(e): chaperonins ; electron microscopy ; FTIR ; molecular modeling ; structure prediction ; contact prediction ; active site prediction ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The three-dimensional structure of the GroES monomer and its interaction with GroEL has been predicted using a combination of prediction tools and experimental data obtained by biophysical [electron microscope (EM), Fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR)] and biochemical techniques. The GroES monomer, according to the prediction, is composed of eight β-strands forming a β-barrel with loose ends. In the model, β-strands 5-8 run along the outer surface of GroES, forming an antiparallel β-sheet with β4 loosely bound to one of the edges. β-strands 1-3 would then be parallel and placed in the interior of the molecule. Loops 1-3 would face the internal cavity of the GroEL-GroES complex, and together with conserved residues in loops 5 and 7, would form the active surface interacting with GroEL. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 71
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 226-244 
    ISSN: 0887-3585
    Schlagwort(e): photosynthesis ; protein structure ; homology modeling ; molecular mechanics ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The reaction center (RC) from the photosynthetic bacterium Rhodobacter (Rb.) capsulatus has been the subject of a considerable amount of molecular biological and spectroscopic work aimed at improving our understanding of the primary steps of photosynthesis. However, no three-dimensional structure is available for this protein. We present here a model obtained by combining information from the structure of the highly homologous RC from Rhodopseudomonas (Rps.) viridis with molecular mechanics and simulated annealing calculations. In the Rb. Capsulatus model the orientations of the bacteriochlorophyll monomer and the bacteriopheophytin on the branch inactive in electron transfer differ significantly from those in the RCs of Rps. Viridis and Rb. Sphaeroides. The bacteriopheophytin orientational difference is in good accord with previous linear dichroism measurements. A comparison is made of interactions between the pigments and the protein environment that may be of functional significance in Rps. viridis, Rb. sphaeroides, and Rb. capsulatus. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 72
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 210-225 
    ISSN: 0887-3585
    Schlagwort(e): serpin-proteinase complex ; mutants ; deamidation ; α-helix-β-sheet conversion ; homology modeling ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The mechanism of formation and the structures of serpin-inhibitor complexes are not completely understood, despite detailed knowledge of the structures of a number of cleaved and uncleaved inhibitor, noninhibitor, and latent serpins. It has been proposed from comparison of inhibitor and noninhibitor serpins in the cleaved and uncleaved forms that insertion of strand s4A into preexisting β-sheet A is a requirement for serpin inhibitor activity. We have investigated the role of this strand in formation of serpin-proteinase complexes and in serpin inhibitor activity through homology modeling of wild type inhibitor, mutant substrate, and latent serpins, and of putative serpin-proteinase complexes. These models explain the high stability of the complexes and provide an understanding of substrate behavior in serpins with point mutations in s4A and of latency in plasmingoen activator inhibitor I. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 73
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 259-266 
    ISSN: 0887-3585
    Schlagwort(e): homology search ; phosphodiesterases ; sequence analysis ; structure prediction ; threading ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The crystal structure of glycerol-3-phosphate cytidylyltransferase from B. subtilis (TagD) is about to be solved. Here, we report a testable structure prediction based on the identification by sequence analysis of a superfamily of functionally diverse but structurally similar nucleotide-binding enzymes. We predict that TagD is a member of this family. The most conserved region in this superfamily resembles the ATP-binding HiGH motif of class I aminoacyI-tRNA synthetases. The predicted secondary structure of cytidylyltransferase and its homologues is compatible with the α/β topography of the class I aminoacyl-tRNA synthetases. The hypothesis of similarity of fold is strengthened by sequence-structure alignment and 3D model building using the known structure of tyrosyl tRNA synthetase as template. The proposed 3D model of TagD is plausible both structurally, with a well packed hydrophobic core, and functionally, as the most conserved residues cluster around the putative nucleotide binding site. If correct, the model would imply a very ancient evolutionary link between class I tRNA synthetases and the novel cytidylyltransferase superfamily. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 74
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 267-272 
    ISSN: 0887-3585
    Schlagwort(e): α-keratin ; intermediate filaments ; epidermal keratin ; vimentin ; keratinopathies ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: In intermediate filaments (IF) both epidermal keratin and vimentin molecules have been shown to have an eight residue head to-tail overlap between the rod domains of similarly directed molecules. In the case of the epidermal keratins this region has also been shown to have particular structural/functional significance since it represents a hot-spot for mutations in the four keratinopathies characterized to date. While there is good evidence that this head-to-tail overlap is present in IF containing Type III, IV, and V chains, as well as in the epidermal keratin IF (Ib/IIb), there are no data currently available for the hard α-keratin IF (Ia/IIa). Using a variety of data derived from X-ray diffraction and crosslinking studies, as well as theoretical modeling, it is now possible to demonstrate that the overlap region is not a feature of hard α-keratin IF. Indeed, it is shown that there is a nine residue gap between consecutive parallel molecules in the IF. An explanation for this observation is presented in terms of compensating disulfide bonds that occur both within the IF, and between the IF and the matrix in which the IF are embedded. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 75
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 245-258 
    ISSN: 0887-3585
    Schlagwort(e): bacterial muramidase ; peptidoglycan ; structure comparison ; sequence motifs ; structure/function relationships ; evolutionary relationships ; X-ray structure ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The 70-kDa soluble lytic transglycosylase (SLT70) from Escherichia coli is a bacterial exo-muramidase that cleaves the cell wall peptidoglycan, producing 1,6-anhydro-muropeptides. The X-ray structure of SLT70 showed that one of its domains is structurally related to lysozyme, although there is no obvious similarity in amino acid sequence. To relate discrete structural features to differences in reaction mechanism and substrate/product specificity, we compared the threedimensional structure of the catalytic domain of SLT70 with the structures of three typical representatives of the lysozyme superfamily: chicken-type hen egg-white lysozyme, goosetype swan egg-white lysozyme, and phage-type lysozyme from bacteriophage T4. We find a particularly close relationship between the catalytic domain of SLT70 and goose-type lysozyme, with not only a significant similarity in overall structure, but even a weak homology in amino acid sequence. This finding supports the notion that the goose-type lysozyme takes up a central position in the lysozyme superfamily and that it is structurally closest to the lysozyme ancestors. The saccharide-binding groove is the most conserved part in the four structures, but only two residues are absolutely preserved: the “catalytic” glutamic acid and a structurally required glycine. The “catalytic” aspartate is absent in SLT70, a difference that can be related to a different mechanism of cleavage of the β-1,4-glycosidic bond. The unique composition of amino acids at the catalytic site, and the observation of a number of differences in the arrangements of secondary structure elements, define the catalytic domain of SLT70 as a novel class of lysozymes. Its fold is expected to be exemplary for other bacterial and bacteriophage muramidases with lytic transglycosylase activity. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 76
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 273-283 
    ISSN: 0887-3585
    Schlagwort(e): globular proteins ; protein structure analysis ; optimal rigid body superposition ; three-dimensional structural motif ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Protein structures are routinely compared by their root-mean-square deviation (RMSD) in atomic coordinates after optimal rigid body superposition. What is not so clear is the significance of different RMSD values, particularly above the customary arbitrary cutoff for obvious similarity of 2-3 Å. Our earlier work argued for an intrinsic cutoff for protein similarity that varied with the number of residues in the polypeptide chains being compared. Here we introduce a new measure, ρ, of structural similarity based on RMSD that is independent of the sizes of the molecules involved, or of any other special properties of molecules. When ρ is less than 0.4-0.5, protein structures are visually recognized to be obviously similar, but the mathematically pleasing intrinsic cutoff of ρ〉1.0 corresponds to overall similarity in folding motif at a level not usually recognized until smoothing of the polypeptide chain path makes it striking. When the structures are scaled to unit radius of gyration and equal principle moments of inertia, the comparisons are even more universal, since they are no longer obscured by differences in overall size and ellipticity. With increasing chain length, the distribution of ρ for pairs of random structures is skewed to higher values, but the value for the best 1% of the comparisons rises only slowly with the number of residues. This level is close to an intrinsic cutoff between similar and dissimilar comparisons, namely the maximal scaled ρ possible for the two structures to be more similar to each other than one is to the other's mirror image. The intrinsic cutoff is independent of the number of residues or points being compared. For proteins having fewer than 100 residues, the 1% ρ falls below the intrinsic cutoff, so that for very small proteins, geometrically significant similarity can often occur by chance. We believe these ideas will be helpful in judging success in NMR structure determination and protein folding modeling. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 77
    ISSN: 0887-3585
    Schlagwort(e): PCB degrading enzyme ; dioxygenase ; crystallization ; polychlorinated biphenyl ; selenomethionine ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Crystals have been obtained for a 2,3-dihydroxybiphenyl dioxygenase (conventionally called BphC) from a polychlorinated biphenyl (PCB)-degrader, Pseudomonas sp. strain KKS1O2. The crystals were grown using both ammonium sulfate and MPD as the precipitating agents. The crystals belonged to a tetragonal space group (I422) and diffracted to 2.5 Å. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 78
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 287-289 
    ISSN: 0887-3585
    Schlagwort(e): DNA repair ; PCR ; Bacillus subtilis ; herpes simplex virus ; protein-protein interaction ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The uracil-DNA glycosylase inhibitory protein (UGI) from the bacterio-phage PBS-l has been cloned and overexpressed. The nucleotide sequence is identical to that for the previously described PBS-2 inhibitor. The recombinant PBS-l UGI inhibits the uracil-DNA glycosylase from herpes simplex virus type-l (HSV-l UDGase), and a complex between the HSV-l UDGase and PBS-l UGI has been crystallized. The crystals have unit cell dimensions a = 143.21 Å, c = 40.78 Å and are in a polar hexagonal space group. There is a single complex in the asymmetric unit with a solvent content of 62% by volume and the crystals diffract to 2.5Å on a synchrotron radiation source. © 1995 Wiley-Liss, Inc.
    Materialart: Digitale Medien
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  • 79
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 290-292 
    ISSN: 0887-3585
    Schlagwort(e): macroH2A ; specialized nucleosomes ; fusion protein ; crystallization ; X-ray diffraction ; noncrystal-lographic symmetry ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Histone macroH2A has a novel hybrid structure consisting of a large nonhistone region and a region that closely resembles a full-length histone H2A. One key to understanding macroH2A function is determining the structure and function of its nonhistone region. The nonhistone region of one of the two known macroH2A subtypes was expressed in Escherichia coli and purified using affinity and molecular sieve chromatography. Crystals of the protein suitable for structural studies were grown from polyethylene glycol solutions by vapor equilibration techniques. The crystals belong to the hexagonal space group P64 (or its enantiomorph P62) with unit cell parameters: a = b = 106.2 Å, c = 125.9 Å, α = β = 90°, and γ = 120°. There are four molecules in the asymmetric unit. Self-rotation function studies revealed three twofold noncrystallographic rotation axes related approximately by 222 symmetry. These crystals have 47% solvent content and diffract to 3.8 Å resolution. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 80
    ISSN: 0887-3585
    Schlagwort(e): aldolase ; protein complex crystallization ; crystallization screening ; X-ray crystallography ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: X-ray quality crystals of class I deoxyribose-5-phosphate aldolase from Escherichia coli have been obtained for the unliganded enzyme and in complex with its substrate, 2-deoxyribose-5-phosphate. The enzyme catalyzes the reversible cleavage of 2-deoxyribose-5-phosphate to acetaldehyde and D-glyceraldehyde-3-phosphate. The unliganded and complex crystals are prismatic long rods and belong to the orthorhombic space group P212121 with cell dimensions a = 183.1 Å, b = 61.4 Å, c = 49.3 Å and a = 179.2 Å, b = 60.5, Å, c = 49.1 Å, respectively. Two molecules in the asymmetric unit are related by a noncrystallo-graphic 2-fold axis. The crystals are stable in the X-ray beam and diffract to at least 2.6 Å. A new method, reverse screening, designed to minimize protein utilization during the screening process was used to determine supersaturation and crystallization conditions. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 81
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995) 
    ISSN: 0887-3585
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 82
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 73-75 
    ISSN: 0887-3585
    Schlagwort(e): thioesterase ; crystallization ; X-ray diffraction ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Thioesterase II from rat mammary gland has been crystallized in the presence of decanoic acid by the vapor diffusion method. The crystals belong to the orthorhombic space group P212121, and have cell dimensions, a = 52.7 Å, b = 78.0 Å, and c = 133.6 Å. The asymmetric unit likely consists of two protein monomers based on predictions from its calculated Matthews coefficient. Crystals typically diffract to at least 2.5 Å resolution and are suitable for X-ray crystallographic analysis. © 1995 Wiley-Liss, Inc.
    Materialart: Digitale Medien
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  • 83
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 76-78 
    ISSN: 0887-3585
    Schlagwort(e): arthritis ; cartilage ; crystallization ; link protein ; proteoglycan aggregate ; X-ray crystallography ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Cartilage extracellular matrix link protein, having molecular mass of approximately 40 kDa, is a metalloprotein that binds divalent cations and is only soluble in low ionic strength solutions. The link protein was purified from bovine trachea and has been crystallized by a vapor diffusion method using PEG 3350 as precipitant. The crystal symmetry is P1, and the unit cell dimensions are a = 43.55, b = 53.11, c = 60.10 Å, α = 90.44, β = 106.21, γ = 101.51°. The VM of 1.8 Å3/Da is consistent with the presence of two molecules of the link protein in the asymmetric unit. The crystals diffract X-rays from a synchrotron source to 1.7 Å resolution. © 1995 Wiley-Liss, Inc.
    Materialart: Digitale Medien
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  • 84
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 100-109 
    ISSN: 0887-3585
    Schlagwort(e): protein structure ; RNA structure ; lattice model ; chain connectivity ; self-avoiding ; dynamic programming ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: An algorithm based on dynamic programming gives the lattice models having the minimal RMS deviations from the actual folds of protein (RNA, etc.) chains for a given lattice and a given orientation of the macromolecule relative to the lattice. The algorithm is applicable for 3-D lattices of any kind. The accuracy of the lattice approximation increases when the distance between neighbor chain links is not rigidly fixed. Special repulsive potentials facilitate generation of self-avoiding lattice chains. The results of model building show the efficiency and precisionof this proposed general method when compared with others. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 85
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 21 (1995), S. 70-73 
    ISSN: 0887-3585
    Schlagwort(e): cell cycle protein ; crystallization ; X-ray diffraction ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The cell cycle regulatory protein CksHs1 has been crystallized in a form suitable for X-ray studies. CksHsl crystals were grown in the presence of vanadate, a phos-phatase inhibitor, but were also obtained with phosphate or tungstate as a cofactor. They belong to the hexagonal space group P6122 with unit cell dimensions: a=b=94 Å, c=131.6 Å, and γ =120. The crystals grown in the presence of vanadate diffract X-rays to at least 2.8 Å. Molecular replacement results from the homologous human CksHs2 structure reveal that a dimer forms the crystal habit, giving the unusual Vm value of 4.4 Å3/Da or a solvent content of 72%. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 86
    ISSN: 0887-3585
    Schlagwort(e): glucocorticoid receptor ; DNA binding domain ; mutant ; yeast ; transcription factor ; transactivation ; modeling ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Regulation of gene expression involves a large number of transcription factors with unique DNA-binding properties. Many transcription factors belong to families of related proteins that bind to similar but distinct sequences. In this study we have analyzed how amino acid substitutions at a single position in the DNA-binding domain modulate the DNA binding specificity within the nuclear receptor family of transcription factors. All possible amino acids were introduced at the first position in the DNA recognition helix, and the specificities of the mutants were analyzed using response elements containing all combinations of bases at two variable base pair positions. All mutant proteins were functional in DNA binding, and could be divided into classes of mutants with different response element specificities. By combining functional data with analysis of the structural effects of the mutations by molecular modeling, we could identify both prohibitive steric interactions as well as positive interactions, such as hydrogen bonds, that function as important determinants for specificity. Only the residues found naturally in the glucocorticoid and estrogen receptors, glycine and glutamate, produce unique binding specificities. The specificities of the other mutants overlap with each other somewhat but the substitutions clearly have potential to contribute to diversity within the nuclear receptor family. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 87
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 119-131 
    ISSN: 0887-3585
    Schlagwort(e): antiparallel β-sheet ; twist ; protein folding ; side chain interactions ; branched amino acids ; cystine-rich proteins ; side chain packing ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Cross-strand pair correlations are calculated for residue pairs in antiparallel β-sheet for two cases: pairs whose backbone atoms are hydrogen bonded together (H-bonded site) and pairs which are not (non-H-bonded site). The statistics show that this distinction is important. When glycine is located on the edge of a sheet, it shows a 3:1 preference for the H-bonded site. Thestrongest observed correlations are for pairs of disulfide-bonded cystines, many of which adopt a close-packed conformation with each cystine in a spiral conformation of opposite chirality to its partner. It is likely that these pairs are a signature for the family of small, cystine-rich proteins. Most other strong positive and negative correlations involve charged and polar residues. It appears that electrostatic compatibility is the strongest factor affecting pair correlation. Significant correlations are observed for β- and γ-branched residues inthe non-H-bonded site. An examination of the structures showsa directionality in side chain packing. There is a correlation between (1) the directionality in the packing interactions of non-H-bonded β- and γ-branched residue pairs, (2) the handedness of the observed enantiomers of chiral β-branched side chains, and (3) the handedness of the twist of β-sheet. These findings have implications for the formation of β-sheets during protein folding and the mechanism by which the sheet becomes twisted. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 88
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 23 (1995), S. 472-490 
    ISSN: 0887-3585
    Schlagwort(e): drug design ; FKBP ; FK506 ; immunophilin ; MCSS ; DLD ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: An automated method for the dynamic ligand design (DLD) for a binding site of known structure is described. The method can be used for the creation of de novo ligands and for the modification of existing ligands. The binding site is saturated with atoms (sp3 carbon atoms in the present implementation) that form molecules under the influence of a potential function that joins atoms to each other with the correct stereochemistry. The resulting molecules are linked to precomputed functional group minimum energy positions in the binding site. The generalized potential function allows atoms to sample a continuous parameter space that includes the Cartesian coordinates and their occupancy and type, e.g., the method allows change of an sp3 carbon into an sp2 carbon or oxygen. A parameter space formulated in this way can then be sampled and optimized by a variety of methods. In this work, molecules are generated by use of a Monte Carlo simulated annealing algorithm. The DLD method is illustrated by its application to the binding site of FK506 binding protein (FKBP), an immunophilin. De novo ligands are designed and modification of the immunosuppressant drug FK506 are suggested. The results demonstrate that the dynamic ligand design approach can automatically construct ligands which complement both the shape and charge distribution of the binding site. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 89
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 23 (1995), S. 491-501 
    ISSN: 0887-3585
    Schlagwort(e): antibody structure ; viral neutralization ; human rhinovirus ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The structure of the complex between the Fab fragment of a human rhinovirus serotype 2 (HRV2) neutralizing antibody (8F5) and a cross-reactive synthetic peptide derived from the viral capsid protein VP2 has been recently determined by crystallographic methods.1 The conformation adopted by the peptide was very similar to and could be superimposed onto the corresponding region of the viral protein VP2 of human rhinovirus 1A (HRV1A) whose three-dimensional structure is known.2 The structure of the Fab fragment determined in the complex was docked onto the viral capsid using the superimposition transformation found for the peptide. In the resulting model the Fab protrudes almost radially to about 60 Å from the surface of the virion without any major steric problem. The Fab fragment was then placed on each one of the 60 equivalent epitopes using the T = 1 icosahedral symmetry of the virus. The closest pairs of Fab fragments are related by viral 2-fold axes and run almost parallel to each other without clashing. These axes of symmetry from the viral particle could thus be coincident with the dyad axes of the antibodies. Furthermore, comparison of the three-dimensional structure of the Fab/peptide complex with the structure of the Fab fragment alone3 indicates that the flexibility of the antibody's elbow would facilitate bivalent attachment to the same viral particle. In accordance with the docking results, experimental determination of the stoichiometry of binding yielded a ratio of 30 IgG molecules per virion also suggesting bivalent attachment of antibody 8F5 onto the viral particle. The neutralization of viral infectivity, being neither aggregation (this paper) nor inhibition of receptor binding,4 might be mainly achieved by reducing viral spread from cell to cell and/or inhibition of uncoating. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 90
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 23 (1995), S. 502-509 
    ISSN: 0887-3585
    Schlagwort(e): microtubules ; molecular motors ; electron cryomicroscopy ; decorated microtubules ; microtubule organization ; structure of microtubule/motor domain complexes ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: To obtain an overall three-dimensional picture of the interaction between microtubules and the motor proteins of the kinesin family it will be necessary to take account of both atomic resolution structures obtained by X-ray crystallography and medium resolution reconstructions obtained by electron cryomicroscopy. We examine the problems associated with obtaining the required structural information from electron micrographs of vitreous ice-embedded microtubules decorated with motor domains. We find that the minus-end directed motor, ncd, decorates microtubules with an 80 Å periodicity as for kinesin. Our theoretical analysis and experiments with ncd illustrate the difficulty in determining unambiguously the surface lattice organization by diffraction analysis of micrographs. 3D reconstructions of decorated microtubules are required to accurately locate the motor domains. Helical diffraction theory is not usually applicable because microtubules are cylindrical structures that rarely have complete helical symmetry. We propose using a back-projection method based on the long pitch helices formed by individual protofilaments. Model reconstructions show that this approach is feasible. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 91
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 23 (1995), S. 525-535 
    ISSN: 0887-3585
    Schlagwort(e): DNA-protein interaction ; crystal structure ; transcription factor ; gene regulation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Many transcription factors have an α-helix that binds to DNA bases in a specific fashion. The DNA-binding geometry of these recognition helices varies substantially. We define a set of parameters to describe the binding geometry of recognition helices and analyze specific stereochemical elements that determine particular geometries. Because the convex surface of the helix must fit into the concave surface of the DNA major groove, the number of degrees of freedom of the recognition helix is reduced from a possible six to a single angle, which we call α. The chemically interacting DNA bases and amino acid residues must lie along a common line and have the same spacing along it. This pairing of base positions with residue positions seems to restrict the binding geometry further to a set of discrete values for α. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 92
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 23 (1995), S. 510-524 
    ISSN: 0887-3585
    Schlagwort(e): lectin ; demetallized ; peptide bond isomerization ; inter-dimer interactions ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The three-dimensional structure of demetallized concanavalin A has been determined at 2.5 Å resolution and refined to a crystallographic R-factor of 18%. The lectin activity of concanavalin A requires the binding of both a transition metal ion, generally Mn2+, and a Ca2+ ion in two neighboring sites in close proximity to the carbohydrate binding site. Large structural differences between the native and the metal-free lectin are observed in the metal-binding region and consequently for the residues involved in the specific binding of saccharides. The demetallization invokes a series of conformational changes in the protein backbone, apparently initiated mainly by the loss of the calcium ion. Most of the Mn2+ ligands retain their position, but the Ca2+ binding site is destroyed. The Ala207-Asp208 peptide bond, in the β-strand neighboring the metal-binding sites, undergoes a cis to trans isomerization. The cis conformation for this bond is a highly conserved feature among the leguminous lectins and is critically maintained by the Ca2+ ion in metal-bound concanavalin A. A further and major change adjacent to the isomerized bond is an expansion of the loop containing the monosaccharide ligand residues Leu99 and Tyr100. The dispersion of the ligand residues for the monosaccharide binding site (Asn14, Agr228, Asp208, Leu99, and Tyr100) in metalfree concanavalin A abolishes the lectin's ability to bind saccharides. Since the quaternary structure of legume lectins is essential to their biological role, the tetramer formation was analyzed. In the crystal (pH 5), the metal-free concanavalin A dimers associate into a tetramer that is similar to the native one, but with a drastically reduced number of inter-dimer interactions. This explains the tetramer dissociation into dimers below pH values of 6.5. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 93
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 23 (1995), S. 536-547 
    ISSN: 0887-3585
    Schlagwort(e): water ; hydrophobicity ; hydration ; X-ray crystallography ; solvation ; ordered solvent ; molecular recognition ; water-protein interactions ; drug and inhibitor design ; protein surface analysis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Water-protein interactions drive protein folding, stabilize the folded structure, and influence molecular recognition and catalysis. We analyzed the closest protein contacts of 10,837 water molecules in crystallographic structures to define a specific hydrophilicity scale reflecting specific rather than bulk solvent interactions. The tendencies of different atom and residue types to be the nearest protein neighbors of bound water molecules correlated with other hydrophobicity scales, verified the relevance of crystallographically determined water positions, and provided a direct experimental measure of water affinity in the context of the folded protein. This specific hydrophilicity was highly correlated with hydrogen-bonding capacity, and correlated better with experimental than computationally derived measures of partitioning between aqueous and organic phases. Atoms with related chemistry clustered with respect to the number of bound water molecules. Neutral and negatively charged oxygen atoms were the most hydrophilic, followed by positively-charged then neutral nitrogen atoms, followed by carbon and sulfur atoms. Agreement between observed side-chain specific hydrophilicity values and values derived from the atomic hydrophilicity scale showed that hydrophilicity values can be synthesized for different functional groups, such as unusual side or main chains, discontinuous epitopes, and drug molecules. Two methods of atomic hydrophilicity analysis provided a measure of complementarity in the interfaces of trypsin:pancreatic trypsin inhibitor and HIV protease:U-75875 inhibitor complexes. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 94
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 21 (1995), S. 226-236 
    ISSN: 0887-3585
    Schlagwort(e): doeking ; Monte Carlo ; LexA repressor ; DNA binding domain ; protein-DNA interaction ; solution structure ; molecular recognition ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: A structural model for the interaction of the LexA repressor DNA binding domain (DBD) with operator DNA is derived by means of Monte Carlo docking. Protein-DNA complexes were generated by docking the LexA repressor DBD NMR solution structure onto both rigid and bent B-DNA structures while giving energy bonuses for contacts in agreement with experimental data. In the resulting complexes, helix III of the LexA repressor DBD is located in the major groove of the DNA and residues Asn-41, Glu-44, and Glu-45 form specific hydrogen bonds with bases of the CTGT DNA sequence. Ser-39, Ala-42, and Asn-41 are involved in a hydrophobic interaction with the methyl group of the first thymine base. Residues in the loop region connecting the two β-sheet strands are involved in nonspecific contacts near the dyad axis of the operator. The contacts observed in the docked complexes cover the entire consensus CTGT half-site DNA operator, thus explaining the specificity of the LexA repressor for such sequences. In addition, a large number of nonspecific interactions between protein and DNA is observed. The agreement between the derived model for the LexA repressor DBD/DNA complex and experimental biochemical results is discussed. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 95
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 21 (1995), S. 256-260 
    ISSN: 0887-3585
    Schlagwort(e): α/β - barrel ; α/β - hyperboloid - 8 ; three-dimensional structure ; local tight packing of hydrophobic groups ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: An analysis of possible tight packing of hydrophobic groups simultaneously at the both surfaces of β-hyperboloid-8 was conducted. This analysis shows that the disposition of amino acid side chains at the real β-structure's surface is unique. If we sign the mean distance between adjacent β-strands as “a,” and the mean distance along β-strand between Cα atoms, whose side chains are directed to one side of the β-sheet, as “b,” the ratio b/a = √2 very precisely. This ratio ensures the most efficient packing of side hydrophobic groups at the outer surface of β-hyperboloid-8, forming, at the same time, the second by efficiency packing at its inner surface. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 96
    ISSN: 0887-3585
    Schlagwort(e): carboxylate ; magnesium ; hydration ; ligand ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The first coordination shell of an Mg(II) ion in a model protein environment is studied. Complexes containing a model carboxylate, an Mg(II) ion, various ligands (NH3, H2S, imidazole, and formaldehyde) and water of hydration about the divalent metal ion were geometry optimized. We find that for complexes with the same coordination number, the unidentate carboxylate-Mg(II) ion is greater than 10 kcal mol-1 more stable than the bidentate orientation. Imidazole was found to be the most stable ligand, followed in order by NH3 formaldehyde, H2O, and H2S. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 97
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 23 (1995), S. 97-110 
    ISSN: 0887-3585
    Schlagwort(e): bovine pancreatic trypsin inhibitor ; cluster analysis ; conformational searching ; molecular dynamics ; protein tertiary structure ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Using energy minimization and cluster analysis, we have analyzed a 1020 ps molecular dynamics trajectory of solvated bovine pancreatic trypsin inhibitor. Elucidation of conformational sub states in this way both illustrates the degree of conformational convergence in the simulation and reduces the structural data to a tractable subset. The relative movement of structures upon energy minimization was used to estimate the sizes of features on the protein potential energy surface. The structures were analyzed using their pairwise root-mean-square Cα deviations, which gave a global measure of conformational changes that would not be apparent by monitoring single degrees of freedom. At time scales of 0.1 ps, energy minimization detected sharp transitions between energy minima separated by 0.1 Å rms deviation. Larger conformational clusters containing these smaller minima and separated by 0.25 Å were seen at 1 ps time scales. Both of these small features of the conformational landscape were characterized by movements in loop regions associated with small, correlated backbone dihedral angle shifts. On a nanosecond time scale, the main features of the protein energy landscape were clusters separated by over 0.7 Å rms deviation, with only seven of these sub states visited over the 1 ns trajectory. These substates, discernible both before and after energy minimization, differ mainly in a monotonic pivot of the loop residues 11-18 over the course of the simulation. This loop contains lysine 17, which specifically binds to trypsin in the active site. The trajectory did not return to previously visited clusters, indicating that this trajectory has not been shown to have completely sampled the conformational substates available to it. Because the apparent convergence to a single region of conformation space depends on both the time scale of observation and the size of the conformational features examined, convergence must be operationally defined within the context of the simulation. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 98
    ISSN: 0887-3585
    Schlagwort(e): antibody-protein complex ; influenza virus hemagglutinin ; protein recognition ; crystallization ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Fab fragments from two different monoclonal antibodies (BH151 and HC45) which bind to the same antigenic region of the influenza hemagglutinin were crystallized as complexes with the hemagglutinin. The complexes crystallize in PEG 600, pH 6.0, and PEG 2000, pH 8.5, respectively. Both crystals belong to space group P321, with very similar unit cell dimensions. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 99
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 22 (1995), S. 187-190 
    ISSN: 0887-3585
    Schlagwort(e): cytokine ; BCRF1 ; protein structure ; crystal seeding ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Crystals of recombinant human interleukin 10 have been grown from solutions of ammonium sulfate. The crystals are tetragonal, space group P41212 or P43212; the unit cell axes are a = 36.5 Å and c = 221.9 Å. There is the equivalent of one polypeptide chain in the asymmetric unit. The crystals are stable to X-rays and diffract to at least 2.5 Å resolution. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 100
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 21 (1995), S. 345-350 
    ISSN: 0887-3585
    Schlagwort(e): methyltransferase ; methylesterase ; protein modification ; S-adenosyl-L-methionine ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: Bacterial chemotaxis receptor modifying enzymes from Salmonella typhimurium have been crystallized using microseeding techniques. The crystals of the S-adenosyl-L-methionine-dependent methyl transferase, CheR, belong to the monoclinic space group P21 with cell constants a = 55.1 Å, b = 48.1 Å, c = 63.1 Å, β = 112.3°. The crystals of the catalytic domain of the methylesterase, CheB, belong to the trigonal space group P3221 or P3121 with unit cell dimensions of a = b = 63.4 Å, c = 86.8 Å. Both crystals contain one molecule per asymmetric unit and have calculated Matthews' volumes of 2.4 Å3/Da. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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