Episodic and TRH induced growth hormone release in primary hypothyroidism of man and rat.

In 27 hypothyroid subjects studied over 20 to 120 minutes, the concentration of serum growth hormone (GH) was variable with the amplitude and frequency of the secretory patterns similar to those reported by others for normal individuals. Serum GH, after the administration of thyrotropin releasing hormone (TRH) did not differ from values observed as spontaneous surges, in contrast to a consistent increase in thyrotropin and prolactin. Episodic secretion of GH persisted in thyroidectomized rats and did not differ significantly from that present in intact controls. It is concluded that episodic GH secretion is not abolished in primary hypothyroidism and that TRH is not a constant GH secretagogue in human subjects with hypothyroidism.     

Demonstration of Ia antigens on mouse intestinal epithelial cells by immunoferritin labeling

Several kinds of epithelial cells that express H-2 antigens were studied by immunoferritin labeling with an antiserum reacting only with antigens of theI region of theH-2 complex. Spleen lymphocytes were used to test the labeling system and the effect of the epithelial cell dissociation procedure on Ia antigens. Immunoglobulin-positive B10.BR lymphocytes were labeled with an anti-la^k serum (A.TH anti-A.TL serum absorbed with BALB/c and B10.D2 cells), while congenic B10.D2 lymphocytes were unlabeled. The distribution of labeled Ia antigens on living B10.BR lymphocytes was patchy, while on cells fixed in periodate-lysine-paraformaldehyde before labeling, the distribution of label was continuous. Fixation evidently immobilized Ia antigens in the lymphocyte membrane. Trypsin and collagenase, as used in the epithelial cell dissociation procedure, had no discernible effect on the Ia antigens of lymphocytes. The epithelial cells studied included the columnar absorptive cells of the small intestine, uterine lining epithelium, tracheal brush cells, and pancreatic exocrine and duct cells. These cells were fixed before dissociation from their respective tissues. Ia antigens were detected only on the columnar absorptive cells of the small intestine. These cells labeled equally well with an antiserum reacting only with theK -end of theH-2 complex. In both cases, congenic control intestinal cells were unlabeled. Thus, intestinal epithelial cells appear to express theIa, K, and presumablyD regions of theH-2 complex, while the other epithelial cell types express only the K and D antigens. On fixed intestinal epithelial cells, Ia and H-2K antigens were continuously distributed on the lateral and basal cell membranes including the zonula adherens, but the antigens were absent from the apical microvillous membrane and the zonula occludens.     

Demonstration of carbohydrate- and protein-determined Ia antigens by monoclonal antibodies

Ten monoclonal alloantibodies were examined by submitting each antibody to five independent tests in order to determine whether they reacted primarily with the glycoprotein or glycolipid class of Ia antigens. The tests employed were as follows: (1) the ability to precipitate an la-like protein from the cell surface as detected by SDS-PAGE; (2) inhibition by protein-la extracts free of CHO-Ia; (3) inhibition by CHO-Ia extracts free of protein-la; (4) neuraminidase sensitivity of the antigen and (5) inhibition by simple sugars. Using these tests, three of the ten monoclonal antibodies were shown to recognize a CHO-Ia antigen while seven recognized the protein class of Ia antigens. The three CHO-Ia-specific monoclonal antibodies recognized Ia specificities 2,9 and 17. Monoclonal antibodies recognizing protein-defined Ia.2 and 17 specificities were also characterized. These results imply that some Ia specificities, as defined by genetic testing, can occur both as carbohydrate-defined and protein-defined determinants.— Sugar inhibition studies showed that CHO-Ia.2 has D-glucosamine as its immunodominant sugar while CHO-Ia. 17 shows preference for a- linked galactose. Furthermore, studies with neuraminidase demonstrated that sialic acid plays a role in the antigenic determinants of CHO-Ia.9 and CHO-Ia.17. Finally, it is noteworthy that CHO-Ia.2, the private specificity of thek haplotype, appears to be expressed only on cells and not in serum. These studies clearly demonstrate the existence of the two Ia antigen classes and emphasize the complexity of the murineI region.     

Demonstration of carbohydrate- and protein determined Ia antigens by monoclonal antibodies

Ten monoclonal alloantibodies were examined by submitting each antibody to five independent tests in order to determine whether they reacted primarily with the glycoprotein or glycolipid class of Ia antigens. The tests employed were as follows: (1) the ability to participate an Ia-like protein from the cell surface as detected by SDS-PAGE; (2) inhibition by protein-Ia extracts free of CHO-Ia; (3) inhibition by CHO-Ia extracts free of protein-Ia; (4) neuraminidase sensitivity of the antigen and (5) inhibition by simple sugars. Using these tests, three of the ten monoclonal antibodies were shown to recognize a CHO-Ia antigen while seven recognized the protein class of Ia antigens. The three CHO-Ia-specific monoclonal antibodies recognized Ia specificities 2, 9 and 17. Monoclonal antibodies recognizing protein-defined Ia.2 and 17 specificities were also characterized. These results imply that some Ia specificities, as defined by genetic testing, can occur both as carbohydrate-defined and protein-defined determinants.--Sugar inhibition studies showed that CHO-Ia.2 has D-glucosamine as its immunodominant sugar while CHO-Ia.17 shows preference for a beta-linked galactose. Furthermore, studies with neuraminidase demonstrated that sialic acid plays a role in the antigenic determinants of CHO-Ia.9 and CHO-Ia.17. Finally, it is noteworthy that CHO-Ia.2, the private specificity of the k haplotype, appears to be expressed only on cells and not in serum. These studies clearly demonstrate the existence of the two Ia antigen classes and emphasize the complexity of the murine I region.     

Comparative studies of α-lactalbumin and lysozyme: The proteins of kangaroo (Megaleia rufa and Macropus giganteus) and horse (Equus caballus)

Summary As part of a study of the whey proteins of various mammals, a comparison is made of the -lactalbumins and lysozymes of the kangaroo and horse. In the milk of the red kangaroo (Megaleia rufa) there is only one -lactalbumin and it occurs throughout lactation, but no lysozyme has been detected. There are two -lactalbumins in the milk of the grey kangaroo (Macropus giganteus), one, designated -lactalbumin Zone B, is present throughout lactation; the second, designated -lactalbumin Zone A, is present only in late lactation. One lysozyme is also present. The milk of the horse (Equus caballus) contains one -lactalbumin and at least one lysozyme. Partial amino acid sequences are proposed from sequence determination and from analyses of tryptic peptides compared with the known sequences of other -lactalbumins and lysozymes.     

Cytogenetic study of a large black kindred: Inversions,heteromorphisms, and segregation analysis

Summary Q-and C-band heteromorphisms were determined by sequentially staining cells from 81 members of an American Black kindred. The incidence of heteromorphs is reported for 14-people who married into the family.Small pericentric inversions of chromosome 3 were found in 23 kindred members, three of whom were homozygous. Six complete chromosome 9 inversions and a single partial inv9 were detected. There was no apparent phenotypic effect associated with the inversions, nor were duplication-deficiency chromosomes observed.Evidence for preferential segregation of Q-heteromorphs is reported, and comparison with data from other authors points to chromosome 13 as showing the most distortion.This paper is based on a thesis submitted by the senior author in partial fulfillment of the Ph. D. degree at North Carolina State University, Raleigh.Research supported by the National Heart and Lung Institute Grant HLO-3341, National Institute of Medical Health Grant MH 2671, and National Institute of General Medical Sciences Grant GM 16697; paper number 6280 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, North Carolina.     

Genetic control of the immune response to the H-2Dk private specificity, H-2.32. II. Genetic linkage analysis of a backcross generation.

B10.AKM mice (H-2M) when immunized with H-2k cells showed very low cytotoxic antibody responses to the H-2Dk private specificity H-2.32, whereas AKR.M and (AKR.M X B10.AKM)F1 mice that possess the same H-2m haplotype mounted reasonable anti-H-2.32 antibody responses. The genetic nature of the non-H-2 linked gene(s) controlling the anti-H-2.32 response was analyzed on the backcross progeny raised between (AKR.M X B10.AKM)F1 and B10.AKM mice. The anti-H-2.32 antibody response was found to be predominantly controlled by a single locus. This locus segregated independently of the Ig heavy chain locus, the Ly2 locus, and the Mls locus. Despite the observed difference in antibody production, no significant differences between AKR.M and B10.AKM mice were detected in induction of H-2Dk-specific killer T cells. Thus, the defect in the response of B10.AKM mice to H-2.32 can be detected at the level of B cell function and is controlled by a single non-H-2-linked genetic locus, but is not attributable to genes linked to the major immunoglobulin structural genes nor to the Mls locus.     

Atrial natriuretic peptide-like immunoreactivity in neurons and astrocytes of human cerebellum and inferior olivary complex.

Atrial natriuretic peptide (ANP) has previously been localized in areas of mammalian brain associated with olfaction, cardiovascular function, and fluid/electrolyte homeostasis. Despite the presence of several types of natriuretic peptide receptors in mammalian cerebellum, neither intrinsic nor extrinsic sources of the natriuretic peptides have been described. In this report we describe the immunohistochemical localization of both intrinsic and extrinsic sources for ANP in human cerebellum. ANP-like immunoreactivity (ANP-LIR) was observed in climbing fibers in the cerebellar molecular layer that probably originated from isolated immunopositive neurons of the inferior olivary complex. Intrinsic sources of ANP-LIR included small subpopulations of protoplasmic and fibrous astrocytes and Bergmann glia, as well as Golgi and Lugaro neurons of the granule cell layer. These results suggest that, in addition to its presumptive roles in local vasoregulation, ANP may serve as a modulator of the activity of Purkinje neurons.     

Fine structure analysis of interaction of FcepsilonRI with IgE

The high affinity receptor for IgE (FcepsilonRI) plays an integral role in triggering IgE-mediated hypersensitivity reactions. The IgE-interactive site of human FcepsilonRI has previously been broadly mapped to several large regions in the second extracellular domain (D2) of the alpha-subunit (FcepsilonRIalpha). In this study, the IgE binding site of human FcepsilonRIalpha has been further localized to subregions of D2, and key residues putatively involved in the interaction with IgE have been identified. Chimeric receptors generated between FcepsilonRIalpha and the functionally distinct but structurally homologous low affinity receptor for IgG (FcgammaRIIa) have been used to localize two IgE binding regions of FcepsilonRIalpha to amino acid segments Tyr129-His134 and Lys154-Glu161. Both regions were capable of independently binding IgE upon placement into FcgammaRIIa. Molecular modeling of the three-dimensional structure of FcepsilonRIalpha-D2 has suggested that these binding regions correspond to the "exposed" C'-E and F-G loop regions at the membrane distal portion of the domain. A systematic site-directed mutagenesis strategy, whereby each residue in the Tyr129-His134 and Lys154-Glu161 regions of FcepsilonRIalpha was replaced with alanine, has identified key residues putatively involved in the interaction with IgE. Substitution of Tyr131, Glu132, Val155, and Asp159 decreased the binding of IgE, whereas substitution of Trp130, Trp156, Tyr160, and Glu161 increased binding. In addition, mutagenesis of residues Trp113, Val115, and Tyr116 in the B-C loop region, which lies adjacent to the C'-E and F-G loops, has suggested Trp113 also contributes to IgE binding, since the substitution of this residue with alanine dramatically reduces binding. This information should prove valuable in the design of strategies to intervene in the FcepsilonRIalpha-IgE interaction for the possible treatment of IgE-mediated allergic disease.     

Cardiovascular responses to hypoxia in the Adriatic sturgeon (Acipenser naccarii)

The in vivo cardiovascular responses to hypoxia, and the intrinsic functional characteristics of the heart in vitro , were determined, and compared, in the Adriatic sturgeon (Acipenser naccarii). During exposure to hypoxia in vivo , blood oxygen content (Cao₂) declined as water 0₂ partial pressure (Pwo₂) was reduced, despite an increase in haematocrit. The main cardiovascular response was a reduction in dorsal aortic blood pressure, with a slight bradycardia, while cardiac output remained constant. Reduced oxygen content of the perfusate had significant inhibitory effects on the intrinsic performance of the heart in vitro , causing a reduction in the heart rate; a reduction in the sensitivity of responses to increased preload (Frank-Starling response), and a more rapid decline in power output and stroke volume when afterload was increased. Overall, the in vitro results suggest that hypoxia depresses the contractility of the heart (i.e. its inotropic responses). The reduction in dorsal aortic pressure in vivo may, therefore, counteract the depressive effects of hypoxia on heart contractility, and thereby avoid a hypoxic depression of cardiac output.