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 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of discrete lesions of the suprachiasmatic and medial preoptic nucleus on luteinizing hormone-releasing hormone (LHRH) neurons of the female rat were examined. The lesions disrupted the estrous cycle and prevented the preovulatory surge of luteinizing hormone and prolactin. Two to three months following the lesions, control and lesioned animals were perfused, the brains were sectioned, and the tissue processed for LHRH immunocytochemistry using the peroxidase antiperoxidase method and a high-titer, conformational antiserum to LHRH. Faintly stained LHRH cells were observed in the preoptic area and the basal hypothalamus at all stages of the estrous cycle. The number of immunoreactive cell bodies varied from a high of 583 cells on proestrus, to a low of 35 cells on estrus (mean +/- SEM = 323 +/- 59; n = 11). In contrast, the constant estrous animals with lesions showed increased intensity and number of LHRH neurons rostral, lateral and caudal to the lesion. The total number of cells ranged from 625 to 954 cells per animal (mean +/- SEM = 784 +/- 44; n = 8; p less than 0.001 vs. controls). Moreover, all lesioned animals exhibited intense fiber stain in the median eminence region. In conclusion, these data support the hypothesis that persistent estrus is caused by destruction of neurons which directly or indirectly control LHRH neurons.
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PMID:Luteinizing hormone-releasing hormone neuronal system during the estrous cycle of the female rat: effects of surgically induced persistent estrus. 352 98

An experimental model of meningeal carcinomatosis has been produced by subarachnoid inoculation of B16 melanoma cells into C57BL mice. Injection of 10(3) viable cells was sufficient to cause 100% tumor incidence and death within a median survival time of 17 days. The tumor infiltrated diffusely the meninges of the brain and spinal cord and filled the ventricular system. Electron microscopic study of the leptomeningeal tumor revealed newly formed microvessels with fenestrated endothelium. The integrity of the blood-brain barrier was studied by the extravasation of the Evans blue and the Horseradish peroxidase tracers. Barrier disruption became evident from the seventh day on, using Evans blue. Electron microscopy study showed peroxidase activity in the luminal and abluminal sides of the meningeal microvessels, and within the tight junctions. Similar findings were noted in cortical capillaries adjacent to the meningeal tumor. Brain concentrations of Adriamycin (ADR) following administration of an intravenous dose of either 10 mg/kg or 50 mg/kg were measured on days 0 to 14 after tumor inoculation. A significant increase in mean +/- SEM content of whole brain ADR was observed only with the 50 mg/kg dose in days 7 to 14 (0.69 +/- 0.02 micrograms/g wet tissue weight) as compared to tumor-free controls (0.43 +/- 0.01, p less than 0.05). Our study suggests that barrier alteration in meningeal carcinomatosis allows extravasation of tracer solutes. Still, in order to achieve a significant increase in a water soluble drug penetration through the disrupted barrier, a high-dose drug regimen is required.
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PMID:Alteration of blood-brain-CSF barrier in experimental meningeal carcinomatosis. A morphologic and adriamycin-penetration study. 355 64

This paper describes the preparation of charged and uncharged protein molecular probes for study of the permselectivity of renal capillaries. Horse heart myoglobin was used as a neutral myoglobin. Since it contained several fractions with different isoelectric points, it was purified by fast protein liquid chromatography (FPLC). To obtain a negatively charged myoglobin, the original horse heart myoglobin was treated with cyanate, resulting in net charge of -5.7 +/- 0.3 at physiological pH (mean +/- SEM). The charge was determined from the Donnan potential which develops over a semipermeable membrane separating the inside solution in which the protein was dissolved from a surrounding bath of equal ionic strength. Sperm whale myoglobin was similarly purified by FPLC and used as a positively (+1.7 +/- 0.2) charged isomer. Horseradish peroxidase (HRP) was purified by means of gel and ion-exchange chromatography and found to be neutral at physiological pH. Negatively charged (-14.0 +/- 0.5) HRP was obtained by succinylation. Two isomers of lactate dehyrogenase (LDH) were used, namely the slightly positive (+2) LDH-M4 and the strongly negative (-19) LDH-H4. These isomers, which occur naturally, did not require further purification. The Stokes-Einstein radii, as measured by gel chromatography, of inulin, myoglobin, HRP and LDH were 11, 17.5, 32 and 46 A, respectively. The chemical modifications did not alter the Stokes-Einstein radii. In biological studies on rat kidneys samples of both plasma and renal hilar lymph were found to contain radioactive low molecular weight degradation products in addition to the intact proteins. This necessitated separation of all individual samples on small Sephadex columns prior to analysis.
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PMID:Permeability of renal capillaries. I. Preparation of neutral and charged protein probes. 357 14

The organization of cytoskeletal proteins in whole-mount adherent platelets from African green monkeys and normal human volunteers has been studied by SEM, high vacuum electron microscopy (HVEM) and conventional (120 kV) electron microscopy. We describe three distinct organizational zones, the Central Matrix, the Trabecular Zone and the Peripheral Web in spread platelets from both sources. The Central Matrix is an ill-defined superstructure of 80-100 A filaments of short length which enshrouded the granules, dense bodies, mitochondria and elements of the open-channel and dense-tubular systems. The latter, identified through the use of peroxidase cytochemistry with the whole mounts, is an anastomosing network of elongate saccules having diameters of 600-1200 A. The Trabecular Zone, which encircles the Central Matrix, contains 165, 80-100 and 30-50 A filaments in an open lattice of irregular lattice spacing. The outermost region of the cells, the Peripheral Web, is comprised of 70 A filaments organized in a honeycomb lattice with center to center spacing in the range 150-300 A. This pattern for the spread cells is not consistently observed in cells during the early stages of adhesion; therefore, correlations of SEM and TEM observations are made for the various stages of adhesion/activation.
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PMID:Cytoskeletal changes during adhesion and release: a comparison of human and nonhuman primate platelets. 373 17

Synovial fluid cells in Reiter's syndrome were studied by cell subset specific monoclonal antibodies and avidin-biotin-peroxidase complex staining. Mean leucocyte count was 9842/mm3 (9.842 X 10(9)/l), and 71% of all cells were polymorphonuclear leucocytes. 26 +/- 11 (SEM)% and 47 +/- 5% of all mononuclear cells in synovial fluid were M1+ monocytes and Ia+ cells, respectively. T11+ T lymphocyte was the predominant synovial fluid mononuclear cell (61 +/- 8%) but, in contrast to the inflammatory joint effusions in rheumatoid arthritis, T4+ cells clearly outnumbered T8+ cells in Reiter's syndrome. Thus the synovial fluid in Reiter's syndrome contains the immunocompetent and accessory cells required for immune response, which in fact is activated as suggested by lymphocyte Ia expression. Furthermore, in contrast with rheumatoid arthritis inducer/helper cells with T4 phenotype seem to be involved preferentially in the local pathogenetic mechanisms in Reiter's syndrome.
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PMID:Synovial fluid cells in Reiter's syndrome. 390 72

We used fracture-label to establish ultrastructural localization of glycoproteins in cross-fractured nuclei of duodenal columnar and exocrine pancreatic cells. Mannose residues were detected in cell nuclei by labeling freeze-fractured tissues with concanavalin A-horseradish peroxidase X colloidal gold (Con A-HRP X CG) or direct concanavalin A X colloidal gold (Con A X CG); fucose residues were detected with Ulex Europaeus I X colloidal gold (UEA I X CG) markers. Areas of the three main intranuclear compartments (euchromatin, heterochromatin, and nucleolus) exposed by freeze-fracture were determined by automated image analysis. Colloidal gold particles bound to each nuclear subcompartment were counted and the results expressed in number of colloidal gold particles per square micrometer +/- SEM. Duodenal and pancreatic tissues fractured and labeled with Con A-HRP X CG complex or direct Con A X CG conjugates showed that the vast majority of Con A binding sites was confined to euchromatin regions with only sparse labeling of the heterochromatin and nucleolus. UEA I labeling of duodenal columnar cells showed that colloidal gold particles were almost exclusively confined to cross-fractured areas where euchromatin is exposed. Trypsinization of the fractured tissues before labeling with Con A and UEA I abolished 95-100% of the original label. Our results show that, within the nucleoplasm, mannose and fucose are residues of glycoproteins preferentially located within the regions of euchromatin.
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PMID:Preferential association of glycoproteins to the euchromatin regions of cross-fractured nuclei is revealed by fracture-label. 394 91

Endothelia lining the 2 surfaces (arterial and ventricular) of the posterior cusp of aortic valves from normocholesterolemic, New Zealand white rabbits were found to display pleomorphic surface features characterized by differences in cellular shape and orientation to the direction of blood flow, microappendage populations (microvilli and blebs), nuclear contours and the surface reactions of cationic dyes (RR, AB) and peroxidase-conjugated lectins (Con A, Limulin, WGA). With the aid of SEM and TEM, the cells lining the arterial surfaces appeared relatively smooth and flattened with a moderate to heavy reaction of the carbohydrate cell coat at the blood interface. By contrast, the contours of the endothelia lining the ventricular surfaces were noticeably raised with numerous plasmalemmal microappendages and only a moderate dye/lectin reaction. Observations of similar endothelial populations from diet-induced, hypercholesterolemic rabbits (500 mg/dl) revealed a variety of dramatic changes in the cells lining the arterial surfaces of the valvular cusps. No severe changes were observed in the endothelia of the ventricular surfaces. Such findings are suggestive further of the importance of the interaction between the environment and the endothelial cell coat as influencing factors in the onset of intramural lipid infiltration.
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PMID:Surface responses of aortic valve endothelia from diet-induced, hypercholesterolemic rabbits. 399 84

We used concanavalin A (con A)-peroxidase-iron dextran-diaminobenzidine (DAB) technique for the electron microscopic detection of con A binding sites on cell membranes. Normal bladder mucosa showed a sparse distribution of con A binding sites with both transmission (TEM) and scanning (SEM) electron microscopy, but bladder tumors showed a higher concentration in the distribution of con A binding sites in proportion to the histopathological grade of transitional cell carcinoma. Quantitative estimation of the con A binding sites was attempted using scanning X-ray pulse analysis of iron elements contained in the reaction complexes. Con A binding sites were quantitatively the smallest in normal mucosa, increasing proportionate to the grade of the bladder tumor. Some specimens were compared by the ferritin-labelled method and the pattern of ferritin conjugates distribution was similar to that seen with the con A-peroxidase-iron dextran method.
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PMID:Distribution of concanavalin A binding sites on normal human urinary bladder mucosa and bladder tumors by transmission and scanning electron microscopy and X-ray microanalysis. 674 Aug 37

The neural retina of avian embryos was spread on a membrane filter and cut in any desired orientation. Strips cut across the retina of 4- to 7-day chick or 3- to 6-day quail embryos were explanted onto collagen gels. Vigorous neurite outgrowth was seen for about 3 days, by which time many neurites were 3 mm long. Horseradish peroxidase (HRP) labeling showed that the cells producing the neurites were large and formed a layer near the inner limiting membrane, indicating that the neurites in vitro were axons of retinal ganglion cells. The size of the neurite population and the regions from which neurites emerged varied with the donor age, while most neurites sprouted from the side of the explant formerly closest to the optic fissure. This pattern closely resembled that of axon growth in the normal retina, as revealed by SEM, silver staining, and HRP labeling. Mitotic inhibitors (Ara-C and FUdR) did not alter the neurite outgrowth. Pretreatment of retinae with trypsin or collagenase did not disorganize axons at the time of explanation, but tended to equalize neurite emergence on each side of the retinal strips. We suggest that microenvironmental factors, especially the enzyme-labile inner limiting membrane, are important for axon guidance in the retina.
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PMID:Oriented axon outgrowth from avian embryonic retinae in culture. 682 32

Lymphocyte populations extracted and separated from hemal nodes (HN) and peripheral blood of 20 male healthy bovines were characterized by surface markers and the rosette-forming test. After treatment with FITC- or peroxidase-conjugated antibovine IgG, about 22% of cells from HN and peripheral blood showed superficial fluorescence (B cells) and about 13% were able to form "E rosettes" (T cells) with sheep erythrocytes pre-treated with neuraminidase. Nearly equal percentages were obtained from peripheral blood lymphocytes. On the basis of the data shown, we can conclude that the function of HN is, at least in healthy animals, analogous with that of lymph nodes. In this study we also used the SEM to evaluate the possibility of classifying the lymphoid cells as B and T lymphocytes on the basis of their surface morphology. Some authors have stated that B and T lymphocytes have a rough and smooth surface, respectively. In our experience, however, because of cells with a moderate number of surface microvilli exist, this method used on its own is not suitable for lymphocyte identification.
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PMID:Identification of lymphocytes extracted from bovine hemal nodes. 698 50


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