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Biomedical subjects

D Richter

Publications and source records attributed to D Richter.

At least 343 records · Page 19Linked to original sources
PubMed1984

Differential responses to osmotic stress of vasopressin-neurophysin mRNA in hypothalamic nuclei.

mRNA encoding the vasopressin-neurophysin precursor was quantitated in individual hypothalamic nuclei of rats by a liquid hybridization assay. Drinking of 2% saline for 14 days, a treatment that increased the plasma vasopressin concentration 9-fold, resulted in a 5- and 2-fold increase in mRNA levels in the supraoptic and paraventricular nucleus, respectively. This osmotic stimulus had no effect on vasopressin-neurophysin mRNA content of the suprachiasmatic nucleus. This dissociation in regulation of vasopressin-neurophysin mRNA in hypothalamic nuclei indicates the existence of two separate vasopressin systems that are independently activated.

Animals↗
PubMed1983

The phosphorylation of ribosomal protein S6 from progesterone-stimulated Xenopus laevis oocytes. Kinetic studies and phosphopeptide analysis.

Xenopus laevis oocytes were prelabeled with [32P]orthophosphate overnight before maturation was induced by progesterone stimulation. The phosphorylation status of ribosomal protein S6 from control oocytes and the temporal changes in S6 phosphorylation after progesterone treatment were analyzed by two-dimensional gel electrophoresis. S6 protein was separated in up to five distinct S6 species, which differed in their degree of phosphorylation. 32P labeling of S6, as judged from the shift of radioactivity into more highly phosphorylated S6 derivatives, continuously increased in progesterone-stimulated oocytes even at later times when germinal vesicle breakdown was completed. S6 protein of unstimulated oocytes was labeled to a lower degree. Trypsin cleavage of total S6 protein, isolated from control and maturing oocytes, gave rise to different complex phosphopeptide patterns reflecting the existence of various multiply phosphorylated S6 derivatives in both samples. Two of the more highly phosphorylated S6 derivatives showed considerable differences between the phosphopeptide elution profiles of control and stimulated oocytes indicating that dissimilar sites had been modified under both physiological conditions. Only phosphoserine was detected in the phosphoamino acid analysis of individual S6 derivatives.

Animals↗
PubMed1983

Structural organization of the rat gene for the arginine vasopressin-neurophysin precursor.

The rat arginine vasopressin-neurophysin precursor gene has been isolated from a genomic library cloned in lambda phage Charon 4A. Restriction mapping and nucleotide sequence analysis demonstrated that the gene is 1.85 kilobase pairs long and contains two intervening sequences located in the protein coding region. Exon A encodes a putative signal peptide, the hormone arginine vasopressin and the variable N terminus of the carrier protein neurophysin, exon B encodes the highly conserved middle part of neurophysin and exon C its variable C terminus together with glycoprotein. Thus, the three functional domains of the percursor - arginine, vasopressin, neurophysin, glycoprotein - are encoded on three distinct exons.

Animals↗
PubMed1983

Epithelioid sarcomas. Three cases.

The authors present two cases of epithelioid sarcoma of the hand and one of the foot with clinical interest. This recently described tumor (Enzinger, 1970), is relatively rare. It occurs in the hand, forearm, pretibial region and foot and affects principally young adults. It should be emphasized, and this is borne out in the literature, that this tumor may appear perfectly benign and often has a course of long duration. The difficult of clinical and especially of histologic diagnosis as well as the difficulty of determining the boundaries of extension of the tumor makes it necessary to carry out radical surgery (amputation or rarely block excision). Every author agrees that local excision is to be condemned, there being an 85% recurrence rate. Spread of the tumor is by way of the fascial planes and tendon sheaths. Lymphatic and pulmonary metastases occur particularly when there is vascular invasion.

Adult↗
PubMed1983

Vasopressin and oxytocin precursors as model preprohormones.

Using a combination of in vitro methodology, including cell-free translation, two-dimensional peptide mapping and recombinant DNA techniques, the structure of the precursors of the hypothalamic nonapeptide hormones vasopressin and oxytocin has been elucidated. Both hormone precursors are model cellular polyproteins in that they comprise several different entities within the same polypeptide molecule. In each precursor, the nonapeptide hormone follows immediately the signal peptide and is, in turn, attached to its respective carrier neurophysin. The vasopressin precursor also includes a pituitary glycoprotein at its C-terminus. The posttranslational processing of the precursors to set free the nonapeptide hormones is thus a critical regulatory step, which can in part be simulated in the quasi in vivo system of the Xenopus laevis oocyte. The preprohormones to vasopressin and oxytocin illustrate well the convenience of the in vitro experimental approach in understanding the function of the peptidergic neuron.

Amino Acid Sequence↗
PubMed1983

[Synthesis and spectrum of pharmacologic action of aryl-arylamino- and aryl-aryliminoacetonitriles].

Aminoacetonitriles were synthetized from arylaldehyde, arylamine and cyanhydrogene. Their dehydrogenation led to the iminoderivatives. The compounds were evaluated for spasmolytic activity in vitro. Some aryl-arylaminoacetonitriles showed significant inhibition of the histamine-induced contraction in guinea-pig ileum and acetylcholine-induced contraction in rat ileum. Structure-activity relationships are discussed.

Acetonitriles↗
PubMed1982

In vitro messenger ribonucleic acid directed synthesis and processing of an immunologically identified precursor to tetradecapeptide somatostatin from bovine hypothalamus.

mRNA isolated from bovine hypothalami was used to direct the in vitro synthesis of a precursor to the tetradecapeptide somatostatin. When a rabbit reticulocyte lysate translation system supplemented with [35S]cysteine was used, a protein of apparent molecular weight 15 500 was identified as preprosomatostatin by reaction with specific rabbit antibodies. Cotranslational addition of dog pancreas microsomal membranes yielded an unglycosylated pro form of 14 500 daltons, implying the removal of a short signal sequence.

Animals↗
PubMed1982

Ribosomal protein S6 from Xenopus laevis ovaries. Isolation, phosphorylation in vivo and cross-reaction with heterologous anti-S6 antibodies.

Ribosomal protein S6 from Xenopus laevis ovaries was prepared by ion-exchange chromatography on phosphocellulose and gel filtration on Sephadex G-75. The protein was identified as S6 from its position on two-dimensional polyacrylamide gels and from its immunological cross-reaction with monoclonal antibody raised against chicken liver S6, and from the fact that it is the major phosphorylated protein of the small subunit. When oocytes were incubated with [32P]orthophosphate in the presence of progesterone, 32P incorporation of 40-S ribosomal proteins was stimulated about 10-fold over controls without hormone. The bulk of the 32P radioactivity was incorporated into protein S6.

Animals↗
PubMed1982

Subcellular transport and ribosomal incorporation of microinjected protein S6 in oocytes from Xenopus laevis.

Protein S6 was isolated from 40S ribosomal subunits of Xenopus laevis oocytes, labeled with sodium boro[3H]hydride, and microinjected back into oocytes. In the first 4 h of incubation, the uptake of S6 into the nucleus increased to a maximum, with, however, no detectable incorporation into 40S ribosomal subunits. After this lag period, S6 was progressively integrated into the small ribosomal subunit. When rRNA transcription was inhibited by actinomycin D, the uptake of S6 into the nucleus and its consequent incorporation into the 40S subunit were significantly reduced. Moreover, when enucleated oocytes were microinjected, little or no S6 was found in the 40S subunits, also suggesting that integration of S6 into ribosomes is linked to rRNA precursor synthesis. In contrast to S6, the acidic protein eL12 isolated from Artemia salina or X. laevis oocyte 60S subunits was integrated into the large subunit independently of the nucleus or active rRNA synthesis.

Animals↗
PubMed1982

Nucleotide sequence of cloned cDNA encoding bovine arginine vasopressin-neurophysin II precursor.

The sequence of a cDNA encoding the nonapeptide arginine vasopressin (AVP) and its carrier protein, neurophysin II (NpII) from bovine hypothalamus, proves that the 166-amino acid precursor molecule contains a signal peptide of 19 amino acids followed directly by AVP connected to NpII by a Gly-Lys-Arg sequence. The carboxy-terminal region of the precursor contains a naturally occurring glycopolypeptide of 39 amino acids which is separated from NpII by a single arginine residue.

Amino Acid Sequence↗
PubMed1982

Fingerprint analysis of bovine hypothalamic preprosomatostatin. Identification of somatostatin-28 at the C terminus.

Messenger RNA from bovine hypothalami was used to direct the synthesis in vitro of a precursor to somatostatin (SRIF) of Mr 15,500. Specific antibodies, raised against the chemically synthesized tetradecapeptide SRIF-14, were used for the preliminary characterization. The radioactively labelled preprosomatostatin was then cleaved by trypsin or cyanogen bromide and the products were assayed by two-dimensional fingerprinting techniques. The results conclusively demonstrated the presence of the tetradecapeptide SRIF-14 sequence and its naturally occurring N-terminally extended form, SRIF-28. This 28-amino-acid sequence was shown to occupy the C terminus of the 15,500-dalton precursor and is probably preceded by basic amino acid(s).

Amino Acid Sequence↗
PubMed1982

Interactions between psychosomatic conflicts and gonadotropin secretion.

This present paper represents an attempt to correlate hormonal patterns and psychoanalytical data in 30 patients with secondary amenorrhea. Based on psychoanalytical data and the maximal LH response to GnRH, which were obtained independently, the patients were divided into two groups presenting differing psychosomatic symptomatologies. Patients with severe psychosomatic disease (group A) complaining predominantly of somatic discomfort, exhibited a weak pituitary response to GnRH. Patients presenting mainly mental symptoms were found to be less affected by the psychosomatic disease (group B). The LH responses to GnRH were only moderately impaired in these patients. Seven patients of group A underwent psychotherapy, resulting in a resumption of regular menses in 4 patients. Eight untreated controls of this group who remained amenorrheic exhibited unaltered gonadotropin in levels. All patients of group B being treated by psychotherapy resumed regular menses, while 5 of 7 control patients developed spontaneous menstruation. The progress of sexual maturation in these patients is correlated with increasing pituitary LH response to GnRH. The present study provides evidence that the degree of a psychosomatic disturbance resulting in secondary amenorrhea is reflected by the pattern of plasma LH after GnRH stimulation.

Adult↗