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Biomedical subjects

J A Parsons

Publications and source records attributed to J A Parsons.

At least 109 records · Page 6Linked to original sources
PubMed1976

Immunocytochemical identification and localization of immunoglobulin A within Paneth cells of the rat small intestine.

Light microscopic immunocytochemistry was used to identify Paneth cells by their lysozyme content and to detect immunoglobulin antigens within a subpopulation of these cells. Antisera specific for the heavy chains of rat or human immunoglobulin A and for immunoglobulin light chain antigens produced specific staining of rat Paneth cells. The distribution of immunoglobulin staining varied between adjacent Paneth cells in the same crypt and between Paneth cells in adjacent crypts, as well as between Paneth cell populations of different animals. No staining of rat Paneth cells was detected using antisera specific for the heavy chain of immunoglobulins G or M. The specific staining of Paneth cells for immunoglobulin A and light chain antigens was blocked by absorption of each antiserum with its respective purified antigen. Absorption of these antisera with purified rat lysozyme did not affect staining and thereby eliminated the possibility of immunologic cross-reactivity between lysozyme and immunoglobulin antigens. It is suggested, in light of current concepts of Paneth cell function, that the immunoglobulin staining of Paneth cells may reflect their ability to phagocytize immunoglobulin A-coated microorganisms or immune complexes containing immunoglobulin A.

Animals↗
PubMed1976

Effects of bone in vitro of bovine parathyroid hormone and synthetic fragments representing residues 1-34, 2-34 and 3-34.

The biological activities of bovine parathyroid hormone (BPTH) and fragments comprising portions of its amino-terminal sequence have been compared in three different assay systems using embryonic rat bone in vitro. Whereas the 3-34 fragment was without significant activity the 1-34 fragment caused all the actions characteristic of BPTH 1-84, extending to bone previous evidence that the amino-terminal residues are sufficient for expression of the biological effects of intact parathyroid hormone. However, the relative potencies of the fragment and the intact hormone were different in the various systems. BPTH 1-34 showed relatively low osteolytic activity and induced anabolic effects in both osteoblasts and cartilage cells of cultivated embryonic mouse radii which were not evoked by the intact hormone. Further work is required to determine the mechanisms responsible for these interesting alterations in relative potency of fragment and native hormone.

Animals↗
PubMed1976

Transplantation of islet tissue in the rat.

Long term reversal of alloxan diabetes has been accomplished by intraperitoneal isotransplantation of enzymatically dispersed neonatal pancreas. In contrast, allotransplanted recipients showed only a transient recovery from the alloxan diabetes followed by a return to the diabetic state at the time of the homograft rejection. These data strongly suggest that the reversal of the diabetic state was a consequence of the transplanted islets. This conclusion is further supported by quantitative analysis of biopsied pancreases from successfully reversed recipients which reveals only 3% of the normal beta cell mass. By comparison, recovery of transplanted islets composed primarily of aldehyde fuchsin positive beta cells was routinely accomplished in these recipients. Utilization of the more specific unlabeled immunoperoxidase method has revealed that some of the transplanted islets are composed of cells positive for glucagon and somatostatin, as well as insulin. Other recovered transplanted islets (generally smaller in size) are composed primarily of one cell type or the other. The presence of insulin, glucagon, somatostatin, and delete pancreatic polypeptide positive cells in the islets of normal rat pancreas has been confirmed. In addition, cells reacting positively for these hormones have been observed in the alloxan diabetic rat pancreatic islets and in islets from reversed recipients. The time required for the disappearance of glycosuria and hyperglycemia (usually occurring from one to eleven weeks posttransplantation) appeared to be related to the amount and age of the donor islet tissue transplanted. Fetal islet tissue was more effective on a per milligram basis in reversing the diabetic state. In addition, while reversal was obtained by transplantation of as little as 5 mg of neonatal islet tissue, relatively large amounts (20 mg) were required before successfully reversed recipients responded normally to glucose tolerance test. By comparison, a similar reversal of diabetes with normal response to glucose load was attained by transplanting only 3 mg of fetal islet tissue. Quantitative morphological evidence of large increases in absolute islet mass, obtained in fetal transplants at the renal subcapsular site suggests that the superiority of fetal islet donor tissue may by in its high growth potential. No adverse effects of an in vitro organ culture period, prior to transplantation, were observed with regard to the ability of neonatal tissue to reverse the diabetic state or for fetal islet tissue to continue to survive at the renal subcapsular site. Likewise, no advantage in regard to amelioration of the homograft rejection response was observed in cultured islet tissue; allotransplants of which were rejected at the kidney site.

Age Factors↗
PubMed1975

A biologically active hormonal fragment isolated from bovine parathyroid glands (BPTH 1-65).

Fresh frozen bovine parathyroid glands were defatted in acetone, when extracted with phenol. Following trichloroacetic acid precipitation, the resultant peptides were chromatographed on Sephadex G-100. Parathyroid hormone (BPTH) characteristically elutes in the fourth peak. However, we also observed significant hormonal activity, both biological and immunological, in the fifth elution peak. The peak V material had potent hypercalcemic activity in the rat and chick, and stimulated adenylate cyclase activity in the rat renal cortex bioassay. This material was further purified by ion exchange chromatography on carboxymethylcellulose in 8 M urea. The biological activity of the purified peptide (3700 MRC units/mg) was equivalent to that of the native hormone on a molar basis. Amino acid analysis, carboxypeptidase digestion, and partial Edman sequence analysis identified this material as BPTH 1-65, a hormonal fragment lacking the C-terminal 19 residues of the 84 residue hormone molecule. Several immunoassays using different anti-PTH antisera had variable reactivity toward the BPTH 1-65 fragment, showing that it may be useful for further characterizing antibody recognition sites. The presence of a lysine residue at position 65 suggests a tryptic-like cleavage may be responsible for the genesis of this hormonal fragment. Further investigation will be necessary to determine if this peptide has physiological significance.

Amino Acid Sequence↗
PubMed1975

Prolactin and growth hormone cells in the human hypophysis: a study with immunoenzyme histochemistry and differential staining.

Growth hormone and prolactin cells were immunostained in human hypophyses with antibody against rat growth hormone or prolactin and the peroxidase-antiperoxidase complex. Growth hormone cells were round and, in normal pituitaries, arranged in sizable groups. Prolactin cells occurred singly and were less numerous; they were often extensively branched. Only a few prolactin cells stained with carmoisine. Incubation of the antibody with an excess of the appropriate antigen greatly diminished or abolished immunostaining; absorption of anti-prolactin with growth hormone often enhanced it. Prolactin cells were somewhat hypertrophied and hyperplastic in a neonate. Many of them stained with carmoisine. An even greater hypertrophy and hyperplasia of these cells (which pushed apart the growth hormone cells) was found in a lactating woman. Immunostained giant prolactin cells were also observed. Staining of the prolactin cells with carmoisine was extensive. Upon prolonged exposure to anti-growth hormone antibody, ACTH/MSH cells also showed immunostaining which was abolished by absorption of the antiserum with growth hormone but not with synthetic 1-24ACTH. Growth hormone cells evidently correspond to the alpha acidophils of Romeis, prolactin cells in lactation to his eta cells; the relation of his epsilon cells to the pleomorphic "resting" prolactin cells is not clear.

Adult↗
PubMed1975

Immunocytochemical localization of somatostatin in cell bodies of the rat hypothalamus.

Cell bodies of small to moderate-sized neurons in the female rat hypothalamus were stained specifically for somatostatin (SRIF) by means of the unlabeled antibody-peroxidase-antiperoxidase immunocytochemical method. SRIF-positive perikarya were scattered throughout the periventricular nucleus in a limited region extending from the middle of the optic chiasm to the rostral margin of the median eminence. The same neurons were revealed with either rabbit (R) or guinea pig (GP) anti-SRIF antisera. Positive cell bodies were more readily assessed with GP antibodies because nonspecific background staining was much less with these than with R anti-SRIF. Positive perikarya were not observed in other hypothalamic nuclei and ependymal elements were also immunocytochemically negative.

Animals↗
PubMed1975

A modification of the unlabeled antibody enzyme method using heterologous antisera for the light microscopic and ultrastructural localization of insulin, glucagon and growth hormone.

The requirement of using homologous antisera (primary antiserum and peroxidase-antiperoxidase (PAP) complex raised in the same species) in the unlabeled antibody enzyme method has been investigated at the light and electron microscopic level using the localization of insulin, glucagon and growth hormone as model systems. Optimum immunocytochemical staining for all three antigens was observed when sheep or goat antirabbit gamma-globulin (S-ARgammaG or G-ARgammaG) were used to couple rabbit peroxidase-antiperoxidase complex with either guinea pig antisera to insulin (GP-AIS) or glucagon (GP-AGS), or monkey antisera to rat growth hormone (M-ARGH). The cross-reactivity between S-ARgammaG or G-ARgammaG and immunoglobulins in these primary antisera were substantiated by immunoelectrophoresis and radioimmunoassay. S-ARgammaG was shown to produce precipitation arcs with GP-AIS and M-ARGH that were similar to those seen when the latter were reacted with rabbit antiguinea pig gamma-globulin antiserum and goat antimonkey gamma-globulin antiserum, respectively. Radioimmunoassay results revealed that immunoprecipitation of 6-10% as compared to homologous antisera controls yielded excellent staining localization when S-ARgammaG was used for immunocytochemistry. Thus, heterologous antisera (primary antiserum and PAP complex raised in different species) may be used in the unlabeled antibody enzyme method as long as the coupling antiserum shows cross-reactivity with immunoglobulins of the primary antiserum and the PAP complex.

Animals↗