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D G Baskin

Publications and source records attributed to D G Baskin.

126 records · Page 7Linked to original sources
PubMed1980

Functional classification of cell types in the growth hormone- and prolactin-secreting rat MtTW mammosomatotropic tumor with ultrastructural immunocytochemistry.

The aim of this study was to identify the neoplastic endocrine cells which contain growth hormone (GH) and prolactin (PRL), in the MtTW15 mammosomatotropic tumor, with ultrastructural immunocytochemistry. We used tumors recovered after 5 to 11 weeks of tumor development, from normal (untreated) rats and from rats treated with the progestin medroxyprogesterone acetate (MPA)--a stimulator of GH secretion in these tumors. Immunocytochemical staining was done with the peroxidase-antiperoxidase technique on ultrathin sections of tumor that had been fixed in glutaraldehyde and postfixed on osmium tetroxide. Immunospecific staining for PRL was found over small (150 nm) secretion granules, whereas staining for GH was deposited on the larger secretion granules (250 nm). Tumors from MPA-treated rats contained profuse numbers of neoplastic cells with large, GH-positive granules. Immunocytochemical staining for GH and PRL was also found in crinophagic, lysosome-like inclusions, particularly in cells that contained many secretion granules. The results support the hypothesis that GH and PRL are produced by separate neoplastic endocrine cell types in the MtTW15 mammosomatotropic tumor, and demonstrate the value of ultrastructural immunocytochemical analysis for functional classification of cell types in chromophobic pituitary adenomas.

Animals↗
PubMed1980

Heterogeneity of the MtTw15 mammosomatotropic tumor. II. Characterization of parenchymal cells by superimposition immunocytochemistry and electron microscopy.

Large MtTw15 tumors, which secrete growth hormone (GH) and prolactin (PRL), are composed of ovoid, elongated, and angular cells which demonstrated interdigitating processes and junctional complexes. The majority of the cells were essentially agranular, but two types of granulated cells were identifiable. One class of granulated cells contained moderate to sparse populations of round dense-cored granules measuring up to 250 nm in diameter. Rod-shaped to filamentous mitochondria with an electron-dense matrix were characteristic of a second class of granulated cells with plemorphic granules of various sizes and electron densities. Images of exocytotic release of the round dense-cored granules were frequently seen, but were not observed with the pleomorphic granules, many of which were judged to be lysosomes. Superimposition immunocytochemistry revealed hormones only in the granulated cells with round to ovoid granules. Morphometry indicated that hormone specific subpopulations of tumor cells can be identified since PRL secretory granules were significantly smaller than GH secretory granules (149 +/- 6 nm for PRL versus 221 +/- 9 nm for GH, P less than 0.001). The vast majority of immunopositive cells contained only GH or PRL, but a few were observed containing both hormones. Ovoid to irregular-shaped nuclei, large lipid inclusions, numerous free ribosomes and polyribosomes, moderate development of the rough endoplasmic reticulum, and prominent Golig profiles were characteristics of all cell types. Irrespective of the presence or absence of cytoplasmic granular elements, particles resembling viruses were encountered in many tumor cells, and these frequently appeared to be budding into the cisternae of the endoplasmic reticulum.

Animals↗
PubMed1979

Immunocytochemistry with osmium-fixed tissue. I. Light microscopic localization of growth hormone and prolactin with the unlabeled antibody-enzyme method.

Growth hormone and prolactin were localized on thin plastic sections of rat anterior pituitary gland and mammosomatotropic tumor MtTW15 that were fixed with osmium tetroxide (alone,mixed with aldehydes, or after aldehydes). Intense immunocytochemical staining for both antigens was obtained after plastic was removed from sections with an alcoholic solution of sodium hydroxide. The results indicated that antigenic determinants of rat prolactin and growth hormone were not completely destroyed or inactivated by fixation with osmium and embedment in epoxy resin, and that removal of the polymerized epoxy resin was necessary to obtain light microscopic postembedding immunocytochemical staining of these antigens. The results also demonstrated that tissues which have been conventionally processed for morphological evaluation by electron microscopy may be suitable for postembedding immunocytochemical staining of some antigens for light microscopy.

Animals↗
PubMed1976

The fine structure of polychaete septate junctions.

Epidermal septate junctions of Nereis sp. and Cirriformia sp. fixed with OsO4 or glutaraldehyde/OsO4 display variable structure in electron micrographs. In transverse section the septa are often indistinct and obscured by opaque material that fills the junctional cleft. Septa (spaced at 180--280 A) are more clearly defined in slightly oblique transverse section; they exhibit an electron lucent center and appear to be linked by arms. En face views of the junction show a honeycomb pattern. Cytoplasmic faces of junctional membranes are backed with plaques opposite the septa. Lanthanum used as a tracer delineates junctional structure in negative contrast. In transverse section a chain-like lattice is present in the junctional cleft. En face vies show parallel rows of pleated elements often linked by arms into honeycomb arrays. Oblique sections demonstrate that these pleated elements are continuous with the chain-like lattice seen in transverse sections. Lanthanum does not pass entirely through the junction. Lanthanum reveals that the septa have a very intricate substructure, but it is difficult to visualize the architecture that could generate the various images presented by these junctions when seen in different orientations. However, it is clear that these junctions possess some features that are diagnostic of several supposedly different types of septate junctions in invertebrates.

Animals↗
PubMed1976

Electron microscopic study on the gill bars of amphioxus (Branchiostoma californiense) with special reference to neurociliary control.

Both primary and secondary (tongue) bars of the pharyngeal gill basket are covered by epithelial cells that are continuous with the cells that line the atrium. Anterior and posterior faces of the gill bars are covered with lateral ciliated cells, which possess a single cilium, ringed by microvilli, and an elaborate basal mitochondria-rootlet apparatus. Pharyngeal faces of the gill bars are covered with ciliated pharyngeal cells, atrial faces by mucus secreting atrial cells. The surface epithelium rests on a stromal septum, a flattened tube of basal lamina which dilates to form the visceral blood vessel (along the pharyngeal face) and skeletal blood vessel (along the atrial face). This basal lamina surrounds paired skeletal rods which run through the longitudinal axis of the gill bars near the atrial face. Between the skeletal rods and atrial cells of primary gill bars is a coelomic channel lined by epithelioid coelomic cells. Neuronal processes, some with neurosecretory granules, are located among the bases of the atrial cells. Some axons may contact lateral ciliated cells where the latter meet atrial cells, but synaptoid endings have not been found here or elsewhere in the gill bars. Nervous tissue has not been identified among lateral ciliated cells even though ciliary activity of these cells is supposedly regulated by atrial nervous tissue.

Animals↗
PubMedDate not supplied

Gamma-endorphin-like peptides in pituitary tissue: evidence for their existence in vivo.

Beta and gamma endorphin-like peptides were measured by radioimmunoassay in whole pituitary. Boiling of acetic acid extracts prior to tissue disruption increased the concentration of both beta E- and gamma E-like peptides. The gamma E-like immunoreactivity from the neurointermediate lobe of the pituitary co-eluted with synthetic gamma E upon gel permeation chromatography. Immunoreactivity for beta E-like and gamma E-like peptides in the intermediate lobe of the pituitary was also shown by immunoperoxidase staining. The results suggest that gamma E-like peptides are present primarily in the pars intermedia in vivo and do not arise as artifacts of acid extraction of pituitary tissue.

Animals↗
PubMedDate not supplied

Characterization and localization of 3H-arginine8-vasopressin binding to rat kidney and brain tissue.

Anatomic, behavioral and pharmacologic evidence suggests that arginine8-vasopressin (AVP) serves as a CNS neurotransmitter or neuromodulator. We have characterized AVP binding to membrane and tissue slice preparations from brain and kidney, and examined the anatomical distribution of these binding sites. Conditions for the binding assay were optimized using kidney medullary tissue. Binding of 3H-AVP (S.A. = 30-51 Ci/mmol, NEN) to brain and kidney membranes and tissue slices was saturable, temperature dependent, linearly related to protein concentration (or number of tissue slices), reversible, and specific since the ability of cold AVP to displace 3H-AVP from binding was greater than oxytocin and other related peptide fragments. Autoradiographic localization of 3H-AVP binding was restricted to kidney medullary tissue. In brain tissue, 3H-AVP binding was found to occur in concentrated foci. Brainstem areas such as the nucleus tractus solitarius (NTS) showed a high density of AVP binding sites. Since local injections of AVP into the NTS have been shown to influence blood pressure, the present study presents the first anatomical evidence for the presence of AVP specific binding sites which might mediate this effect.

Adenylyl Cyclases↗
PubMedDate not supplied

Somatostatin in epithelial cells of intestinal mucosa is present primarily as somatostatin 28.

Region-specific antisera to [Tyr14]-SS28(1-14) were used to identify cells containing immunoreactivity to the SS28(1-14) fragment of somatostatin 28 (SS28) in gastric and intestinal mucosal epithelium and in pancreatic islets by immunoperoxidase staining. Radioimmunoassay with iodinated [Tyr14]-SS28(1-14) identified one antiserum (F4) to SS28(1-14) that cross-reacted equally with SS28(1-12), SS28(1-14) and SS28. Two other antisera (F3 and F8) to SS28(1-14) did not cross-react with SS28(1-12) and showed insignificant cross-reactivity to SS28. Immunostaining results showed that F4 stained the same cells that reacted with antiserum AS-10, which is specific for the cyclic tetradecapeptide somatostatin, SS28(15-28). Antisera F3, F4, and F8 all reacted with islet D cells and with somatostatin cells in the antral mucosa. However, only antiserum F4 detected immunoreactivity in mucosal epithelial cells; F3 and F8 did not bind to these cells. After sections of intestine were exposed to trypsin, however, epithelial cells containing immunoreactivity to SS28(1-14) were detected in intestinal mucosa with antisera F3 and F8. These results were obtained for duodenum, jejunum, ileum, and colon, but most of the epithelial cells with immunoreactivity to SS28(1-14) were in the duodenum. Both radioimmunoassay and immunostaining results suggest that F3 and F8 bind to a region of SS28(1-14) that is unavailable to antibodies in the intact SS28 molecule.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Insulin binding in the hypothalamus of lean and genetically obese Zucker rats.

Recent reports have suggested that the obesity and hyperphagia of the genetically obese Zucker rat may be related to defective insulin action or binding in the hypothalamus. We used quantitative autoradiography to determine if insulin binding is altered in specific hypothalamic nuclei associated with food intake. Insulin binding was measured in the arcuate (ARC), dorsomedial (DMN), and ventromedial (VMN) hypothalamic nuclei of 3-4-month-old lean (Fa/Fa) and genetically obese (fa/fa) Zucker rats. A consistently reproducible 15% increase in the total specific binding of 0.1 nM [125I]-insulin was found in the ARC of the obese genotype. A slight increase in insulin binding in the DMN was also found. No difference in specific insulin binding was found between genotypes in the VMN. Nonlinear least squares analysis of competitive binding studies showed that the Kd of the ARC insulin binding site was 33% higher in the lean rats than in the obese rats, indicating an increased affinity for insulin. No difference in site number (Bmax) was found in the ARC, DMN or VMN, and no evidence was found for reduced insulin binding in the hypothalamus of the obese (fa/fa) genotype. The results suggest that hyperphagia and obesity of the obese (fa/fa) Zucker rat genotype may be associated with increased insulin binding in the arcuate nucleus.

Animals↗
PubMedDate not supplied

Insulin binding to brain capillaries is reduced in genetically obese, hyperinsulinemic Zucker rats.

In order to study the role of plasma insulin in regulating the binding of insulin to the endothelium of the blood-brain barrier (BBB), insulin binding to a purified preparation of brain capillaries was measured in both genetically obese Zucker rats and lean Zucker controls. We found a reduction of 65% in brain capillary insulin binding site number in the obese compared to lean rats with no change in receptor affinity. Furthermore, specific insulin binding to brain capillaries was negatively correlated (p less than 0.05) to the plasma insulin level, suggesting a role for plasma insulin in regulating insulin binding. A similar relationship was observed between insulin receptor number in liver membranes and the plasma insulin level. We conclude that obese, hyperinsulinemic Zucker rats exhibit a reduction in the number of BBB insulin receptors, which parallels the reduction seen in other peripheral tissues. Since insulin receptors have been hypothesized to participate in the transport of insulin across the BBB, the reduction observed in the obese rats may account for the decrease in cerebrospinal fluid insulin uptake previously demonstrated in these animals.

Animals↗
PubMedDate not supplied

Localization and measurement of neurotransmitter receptors in rat and human brain by quantitative autoradiography.

Receptors for neurotransmitters can be visualized and characterized using in vitro tissue slice binding techniques and quantitative autoradiography. In this article, the general methods used in studies of this type are outlined and specific application to the study of catecholamine and neuropeptide receptors in rat and human brain tissue are described. Receptor autoradiography is used to examine regulation of dopamine receptor density in response to denervation and replacement of dopamine using brain transplants. Morphological and pharmacological aspects of vasopressin receptor ontogeny in the rat brain are examined. Finally, autoradiographic data on catecholamine receptor localization and characterization in the human hypothalamus, locus coeruleus, and frontal cortex are presented and discussed with reference to their applications in the study of neuropsychiatric disorders such as schizophrenia and senile dementia of the Alzheimer's type.

Animals↗