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J E Pintar

Publications and source records attributed to J E Pintar.

70 records · Page 4Linked to original sources
PubMed1985

Specific cellular expression of monoamine oxidase B during early stages of quail embryogenesis.

Monoamine oxidase-B (MAO-B) is one of two distinct molecular forms of MAO that in part regulate the cellular levels of biogenic amines. In order to determine whether discrete cell populations known to express aminergic properties in the vertebrate embryo also express MAO-B, the distribution of MAO-B-immunoreactive cells was examined in early developing quail embryos. Two major patterns of staining emerge. First, tissues known to express several aminergic characteristics are initially MAO-B positive at early stages of development and continue to express immunoreactivity through Zacchei stage 20, the oldest stage examined. These include cells of the sympathetic and some cranial and trunk sensory ganglia (beginning at stage 13), the pancreas (stage 14), and the brain stem raphe (stage 14). Second, other structures that contain or accumulate biogenic amines are transiently MAO-B immunopositive during early stages of development. These tissues include extraembryonic yolk sac and presumptive gut endoderm (with most intense staining between stages 8 and 13), the ventral trunk neural tube (stages 14 and 16), and the notochord (stages 8-10). MAO-B immunoreactivity disappears from these regions at different stages, and none are MAO-B positive by stage 19-20. Other structures without known aminergic properties during early development also stain; these include liver (stage 20), mesenchymal cells that surround the Wolffian duct and lung buds (stages 14 and 18), and endothelial cells surrounding the dorsal aorta (stages 14 and 20). In general, however, MAO-B appears to be distributed in embryonic tissues that can use this enzyme to regulate biogenic amine levels either transiently or during initial phenotypic expression of aminergic traits.

Animals↗
PubMed1984

Characterization and localization of proopiomelanocortin messenger RNA in the adult rat testis.

Northern blot analysis of total RNA and polyadenylated RNA isolated from adult rat testes showed that a proopiomelanocortin (POMC)-like messenger RNA molecule is present in these extracts. The testicular POMC messenger RNA is comparable in length to amygdala and midbrain POMC messenger RNA and appears to be at least 200 nucleotides shorter than POMC messenger RNA found in the hypothalamus and anterior and intermediate lobes of the pituitary gland. Hybridization in situ showed that POMC messenger RNA is located in Leydig cells, which are the only testicular cells that contain immunostainable POMC-derived peptides. These results suggest that local synthesis of POMC occurs in the testis.

Animals↗
PubMed1984

Biosynthesis and processing of pro-opiomelanocortin-derived peptides during fetal pituitary development.

We have investigated the molecular weight forms of pro-opiomelanocortin (POMC)-derived peptides present in rat pituitaries during fetal and early postnatal development (embryonic Day 14 to 3 day neonate). At all early ages examined, the major immunoreactive form of corticotropin (ACTH) was POMC. Only during late fetal and early postnatal stages did progressively larger amounts of 4.5K ACTH, a major POMC processing end product, appear. This form was found almost exclusively in isolated anterior lobes. In contrast, 3.5K size endorphin(s), another POMC derivative, were present in whole glands even at early stages (Day 14), and were the major POMC derivative(s) found in isolated intermediate-posterior lobes of older fetuses. Despite the early appearance of 3.5K endorphin(s), alpha-MSH did not appear until Day 19 and was detected only in isolated intermediate-posterior lobes. We have also cultured dispersed fetal pituitary cells in the presence of radioactive amino acids. After immunoprecipitation using affinity-purified antisera, followed by fractionation of the radiolabeled products, we found that POMC biosynthesis does occur in cultures of Day 14 embryonic pituitary cells, and that the major POMC-derived end product produced is 3.5K size endorphin(s). These findings demonstrate that POMC is synthesized at least by Day 14 of rat pituitary development and that lobe-specific processing characteristic of the corresponding adult lobe is apparent at the earliest stages that the lobes can be separated. The presence of 3.5K-sized endorphins at early ages is consistent with the possibility that POMC synthesis first occurs in the intermediate lobe. The noncoordinate appearance of alpha-MSH, 1-39 ACTH, and endorphins implies that the activities of certain cleavage enzymes and acetylation enzymes responsible for lobe-specific post-translational POMC processing may be expressed at different times during development.

Adrenocorticotropic Hormone↗
PubMed1983

Specificity of antisera prepared against pure bovine MAO-B.

Antisera have been prepared against purified bovine MAO-B that appear to react selectively with MAO-B and not MAO-A, Rabbit and mouse antisera indirectly immune precipitated [125I]bovine MAO-B using inactivated Staphylococcus aureus cells, and binding of antibodies to bovine and rat MAO-B did not inhibit enzyme activity. Two continuous rat cell lines, hepatoma line MH1C1 and glioma line C6, were used to elucidate the specificity of the antisera. MH1C1 cells, which express both MAO-A and MAO-B, showed immune-specific staining with rabbit antiserum, and staining was blocked with pure MAO-B. Further, MAO-B activity and [3H]pargyline-labeled MAO molecules could be immune precipitated from solubilized mitochondrial preparations of MH1C1 cells; and immune fixation of mitochondrial proteins following SDS polyacrylamide gel electrophoresis (SDS-PAGE) revealed staining of the MAO-B, but not of the MAO-A, flavin-containing subunit. In contrast, no immune-specific immunocytochemical staining was observed in C6 cells, which have only MAO-A activity; no MAO-A activity or [3H]pargyline-labeled MAO could be immune precipitated from solubilized mitochondrial preparations of these cells, and no stained bands were observed for mitochondrial proteins resolved by SDS-PAGE and processed for immune fixation. Further support for the selectivity of this antiserum for MAO-B comes from immunocytochemical staining of rat tissues which express varying amounts of MAO-A and MAO-B activities. Hypothalamus and liver, with high levels of MAO-A and MAO-B activities showed a large number of immunoreactive cells, whereas spleen, heart and superior cervical ganglia, with high MAO-A and low MAO-B activities showed only a few or no stained cells. Catecholamine neurons in the substantia nigra, thought to contain MAO-A, did not show immune-specific staining. Skeletal muscle cells with low MAO-A and MAO-B activities did not stain. These studies provide additional evidence that MAO-A and MAO-B are distinct molecules, differentially expressed in different cell types.

Animals↗
PubMed1982

Monoamine oxidase (MAO) activity as a determinant in human neurophysiology.

Several lines of evidence indicate that monoamine oxidase (MAO) activity can regulate levels of biogenic amines and neuronal activity in the nervous system. The two types of MAO activity, A and B, appear to have different domains of activity in the body. Brain tissue has both types of activity, although adrenergic neurons are thought to contain exclusively MAO-A. MAO activity can also be measured in peripheral tissues: MAO-A in cultured skin fibroblasts and placenta, and MAO-B in platelets and lymphocytes. These two types of activity are mediated by different enzyme molecules and are regulated independently by endogenous and exogenous factors including genetic determinants, hormones, and aging. In humans, inhibition of MAO-A activity leads to mood elevation in depressed patients; in contrast, low MAO-B activity in platelets has been associated with an increased susceptibility to psychopathology. In order to assess further the role of MAO activity in human mood and behavior, it will be important to measure both forms of the enzyme independently and to establish correlations between levels of activity and discrete phenotypic traits.

Adrenergic Fibers↗
PubMed1982

Immunocytochemical demonstration of monoamine oxidase B in brain astrocytes and serotonergic neurons.

An antiserum to monoamine oxidase B (MAO-B) was used to define the distribution of this metabolic enzyme in the adult rat brain immunocytochemically. MAO-B is specifically located in two major central nervous system cell classes, astrocytes and serotonin-containing neurons. Double-immunofluorescence experiments using antisera to glial fibrillary acidic protein and MAO-B showed that both protoplasmic and fibrillary astrocytes throughout the brain contain MAO-B, whereas oligodendrocytes do not contain the enzyme. Areas lacking a blood-brain barrier, such as the specialized circumventricular organs, also contain MAO-B-positive cells. A double-immunofluorescence experiment using antisera to serotonin and MAO-B enabled the positive identification of neurons containing both molecules. The catecholamine-containing neurons of the brain did not contain detectable amounts of MAO-B. The specific distribution of MAO-B in the adult central nervous system indicates that the role of MAO-B in monoamine metabolism may be more specifically defined than previously believed.

Animals↗
PubMed1981

Analysis of developmentally homogeneous neural crest cell populations in vitro. IV. Cell proliferation and synthesis of glycosaminoglycans.

Glycosaminoglycans (GAG) have been implicated as regulators of morphogenesis and differentiation. We have cultured two different homogeneous populations of quail trunk neural crest cell with different predictable phenotypes after equivalent times in culture, and used these populations to distinguish changes in GAG synthesis before and after cell differentiation from changes that depend on time in culture, and that thus may reflect a non-specific response to in vitro culture conditions. Cells derived from the outgrowths surrounding explanted neural tubes remained undifferentiated. These crest cells showed a decrease in [3H]glucosamine incorporation into total GAG with time in culture. A similar decrease in total GAG, and, in addition, a slight decrease in the proportion of hyaluronic acid (HA) was observed in cultures of cluster-derived cells that homogeneously differentiated into melanocytes. Putative mouse neural crest cells that did not form melanin under the present culture conditions showed, similarly to the quail neural crest cells, a high incorporation of [3H]glucosamine into HA relative to sulfated GAG. The proportion of HA did not decrease with time in culture in these mouse crest cells. When pigment granules appeared in avian crest cells, the proliferation rate decreased drastically, whereas the proliferation rate of cells that did not form pigment granules remained constant. The results indicate that time in culture rather than either a differentiation per se or a change in the rate of proliferation, is largely responsible for the observed changes in GAG synthesis.

Animals↗
PubMed1981

Differences in the structure of A and B forms of human monoamine oxidase.

[3H]Pargyline-labeled polypeptides associated with the A and B types of monoamine oxidase (MAO) activity in human tissues were analyzed by sodium dodecyl sulfate--polyacrylamide gel electrophoresis (SDS-PAGE). [3H]Pargyline was bound to MAO A in a crude mitochondrial fraction from the placental trophoblast of a male newborn and to MAO B in blood platelets from the umbilical vein of the same newborn. [3H]Pargyline was also bound to MAO A and B in a crude mitochondrial fraction from cultured skin fibroblasts of a male adult and to MAO B in blood platelets from the same individual. Specific labeling of proteins associated with type A or type B activity in fibroblast cells was achieved by preincubation with selective B or A inhibitors, respectively. For all tissues, SDS-PAGE of [3H]pargyline-bound samples revealed a labeled protein band of apparent molecular weight 63,000 for MAO A and 60,000 for MAO B. When SDS-solubilized, [3H]pargyline-labeled MAO A and B proteins from the same male newborn were subjected to limited proteolysis and one-dimensional peptide mapping in SDS gels, different patterns of [3H]pargyline-labeled peptides were obtained. These findings indicate that distinct enzyme molecules are associated with the A and B types of human MAO activity.

Adult↗
PubMed1981

Gene for monoamine oxidase type A assigned to the human X chromosome.

Inherited variations in monoamine oxidase (MAO) activity are thought to affect human behavior and expression of disease. The present study has established the chromosomal location of one of the structural genes coding for this enzyme. Mapping was carried out by somatic cell hybridization between normal human skin fibroblasts and mouse neuroblastoma cells. Selective media for growth of cells with or without hypoxanthine phosphoribosyltransferase (HPRT) activity were used to obtain hybrid lines which had retained or lost the human X chromosome, respectively. Cytogenetic techniques, isozyme analysis, and limited proteolysis and peptide mapping of [3H]pargyline-labeled MAO were used to characterize hybrid lines. With one exception, only lines containing the human X chromosome and human forms of two X-linked enzymes (phosphoglycerate kinase and glucose-6-phosphate dehydrogenase) expressed the human form of the flavin polypeptide of type A MAO. The exceptional hybrid line contained a putative translocation of part of the human X chromosome, since it expressed human forms of both MAO and phosphoglycerate kinase but neither the human form of glucose-6-phosphate dehydrogenase nor HPRT activity. This evidence indicates that the structural gene for the flavin polypeptide of MAO-A is on the human X chromosome. This represents the first chromosomal assignment of a human gene coding for an enzyme of neurotransmitter metabolism. This information will help to elucidate the structure of MAO and modes of its inheritance in the human population.

Animals↗
PubMed1978

The histochemical specificity of Streptomyces hyaluronidase and chondroitinase ABC.

Treatment of tissue sections with enzymes wich degrade specific types of glycosaminoglycans should provide a means for localizing glycosaminoglycans in tissue sections. The feasibility of this technique was examined by utilizing endogenously labelled glycosaminoglycans in chick and quail embryos. Less than 8% of the total glycosaminoglycans appear to be lost non-specifically during fixation and dehydration. Both Streptomyces hyaluronidase and chondroitinase ABC degraded more than 90% of their respective substrates and demonstrated minimal non-specific extraction of other glycosaminoglycans. The selectivity of chondroitinase ABC for sulphated glycosaminoglycans was substantially increased by raising the pH of the incubation buffer to 8.6. At this pH, chondroitinase ABC degraded negligible amounts of hyaluronic acid. Use of both Streptomyces hyaluronidase and chondroitinase ABC confirmed that embryonic hyaluronic acid binds Alcian Blue under conditions that were previously believed specific for sulphated glycosaminoglycans. We suggest that this may be due to the increased molecular weight of embryonic hyaluronic acid compared to the hyaluronic acid in adult tissues. The results presented suggest that treatment of adjacent sections with buffer, chondroitinase ABC at pH 8.6, and Streptomyces hyaluronidase and subsequent staining with Alcian Blue provides a method for localizing and quantitating glycosaminoglycans in tissue sections.

Alcian Blue↗
PubMedDate not supplied

Expression of IGF system genes during T-antigen driven pituitary tumorigenesis.

Expression of IGF-I, IGF-II, the Type-I IGF receptor and six IGF binding proteins were examined in three different T-ag-driven mouse tumors. Unlike the widespread expression of IGF-II in pancreatic beta-cell tumors, IGF-II was not widely expressed in the two different pituitary tumors examined indicating that a mechanism independent of focal IGF-II expression can also drive T-antigen tumorigenesis. In addition, multiple IGF binding proteins were expressed in all three tumor types. This expression, however, was generally heterogeneous with no specific changes to indicate a required role for any IGF binding protein in T-antigen tumorigenesis.

Animals↗