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Biomedical subjects

J Drouin

Publications and source records attributed to J Drouin.

At least 109 records · Page 6Linked to original sources
PubMed1985

The pronatriodilatin gene is located on the distal short arm of human chromosome 1 and on mouse chromosome 4.

Atrial natriuretic factors (ANF) are polypeptides having natriuretic, diuretic, and smooth muscle-relaxing activities that are synthesized from a single larger precursor: pronatriodilatin. Chromosomal assignment of the gene coding for human pronatriodilatin was accomplished by in situ hybridization of a [3H]-labeled pronatriodilatin probe to human chromosome preparations and by Southern blot analysis of somatic cell hybrid DNAs with normal and rearranged chromosomes 1. The human pronatriodilatin gene was mapped to the distal short arm of chromosome 1, in band 1p36. Southern blot analysis of mouse X Chinese hamster somatic cell hybrids was used to assign the mouse pronatriodilatin gene to chromosome 4. This assignment adds another locus to the conserved syntenic group of homologous genes located on the distal half of the short arm of human chromosome 1 and on mouse chromosome 4.

Animals↗
PubMed1984

Morphometric analysis of platelets in Bernard-Soulier syndrome: size and configuration in patients and carriers.

Quantitative ultrastructural morphometric analysis has been carried out on thin sections of platelets from two Bernard-Soulier sisters and their parents. Measurements were made for the major and minor axes, axial ratios, cross-sectional circumference and cross-sectional area. Platelets were collected either into CPD anticoagulant or directly into glutaraldehyde. The results confirm that Bernard-Soulier platelets are significantly larger than normals (p less than 0.05) in all the parameters mentioned and indicate (I) that the morphology of platelets from Bernard-Soulier patients is affected by the presence of anticoagulant, and (II) a more spherocytic configuration is characteristic of Bernard-Soulier disease both in patients and carriers.

Blood Coagulation Disorders↗
PubMed1984

Molecular cloning and characterization of DNA sequences encoding rat and human atrial natriuretic factors.

A cDNA copy of the message encoding rat atrial natriuretic factor (ANF) has been cloned in Escherichia coli, and its nucleotide sequence was determined. ANF appears to be synthesized as a larger precursor, atrial pronatriodilatin. The cDNA has an open reading frame potentially encoding a protein of 152 amino acids, of which the first 24 amino acids strongly resemble a signal sequence. This is followed by a sequence with 80% homology to a second vasoactive protein, porcine cardiodilatin. The ANF peptide is contained in the COOH-terminal portion of the protein. The DNA sequence corresponding to human ANF is also presented and displays a high degree of homology to its rat counterpart. These data provide further evidence for the expression in cardiac atria of a multifactor system that may contribute to the regulation of blood pressure and extracellular fluid volume.

Amino Acid Sequence↗
PubMed1984

Intracranial plasmacytoma associated with multiple myeloma.

A 58-year-old man with multiple myeloma presented with a 3-month history of a sensation of occipital pressure, transient blurring of vision and increased bone pain. Funduscopic examination revealed disc swelling, tortuous veins and superficial retinal hemorrhages simulating early hyperviscosity syndrome. Clinical investigation and computerized tomography, however, indicated that an intracranial plasmacytoma was the cause of his papilledema. Cobalt 60 beam therapy and vincristine were added to his treatment regimen. Seven weeks later the intracranial tumour had almost totally disappeared. Symptomatic cerebral compression from an intracranial plasmacytoma associated with systemic disease is uncommon. The diagnosis and management are reviewed.

Brain Neoplasms↗
PubMed1983

Complete structure of the porcine pro-opiomelanocortin mRNA derived from the nucleotide sequence of cloned cDNA.

Polyadenylated RNA isolated from porcine pituitary neurointermediate lobes was used to construct a cDNA library. The library was screened with a rat genomic DNA fragment specific for pro-opiomelanocortin sequences. Two positive clones, pJA-19 and pJA-20, containing respectively 850 bp and 550 bp were characterized. Sequence analysis of the cDNA inserts revealed the complete structure of the porcine pro-opiomelanocortin mRNA. This mRNA would include 129 5'-untranslated nucleotides, 801 nucleotides coding for the 267 amino acids precursor and 162 3'-untranslated nucleotides. Comparison with pro-opiomelanocortin mRNA sequences from other species shows regions of high homology not only in the coding sequences but also in the 5'untranslated region where the first 50 nucleotides are over 80% purines.

Adrenocorticotropic Hormone↗
PubMed1981

Sequence and organization of the human mitochondrial genome.

The complete sequence of the 16,569-base pair human mitochondrial genome is presented. The genes for the 12S and 16S rRNAs, 22 tRNAs, cytochrome c oxidase subunits I, II and III, ATPase subunit 6, cytochrome b and eight other predicted protein coding genes have been located. The sequence shows extreme economy in that the genes have none or only a few noncoding bases between them, and in many cases the termination codons are not coded in the DNA but are created post-transcriptionally by polyadenylation of the mRNAs.

Base Sequence↗
PubMed1981

Interactions between 17 beta-estradiol and progesterone in the control of luteinizing hormone and follicle-stimulating hormone release in rat anterior pituitary cells in culture.

After preincubation of rat anterior pituitary cells in culture for 48 h with 10(-9) M 17 beta-estradiol (E2), basal LH release is increased 1- to 2-fold, while the concentration of LHRH required to induce a half-maximal stimulation (ED50) of LH release is approximately 50% reduced. The presence of 10(-7) M progesterone (P) alone for 48 h has no effect on LH release, but it inhibits the sensitizing action of E2 on the LH response to LHRH. This inhibitory effect of P on the E2-induced increase of LH responsiveness to LHRH is similar to the effect of androgens. While not affecting the LHRH ED50 for FSH release, P stimulates both basal FSH release and the maximal FSH response to LHRH. This effect of P is potentiated by simultaneous incubation in the presence of E2. The stimulatory effect of E2 alone on LH release is exerted at an ED50 value of 1-2 x 10(-11) M. A similar ED50 value is found for the potentiating effect of E2 on the P-induced stimulation of FSH release. The stimulatory effect of E2 on LH responsiveness to LHRH appears to be due to changes in the sensitivity of the release mechanisms in gonadotrophs, since the total hormone content (release plus cell content) is not affected by E2 under the same experimental conditions. The stimulatory effect of P on FSH release is measured at an ED50 value of 1 x 10(-8) M and is maximal after approximately 8 h of incubation with the steroid. While not affecting total LH, P increases total FSH (release plus cell content), indicating that the stimulatory effect of P on FSH release could be secondary to changes in the hormone content of cells.

Animals↗
PubMed1980

Most of the coding region of rat ACTH beta--LPH precursor gene lacks intervening sequences.

The peptide hormones ACTH, beta-endorphin, alpha- and beta-melanotropin(MSH) and possibly gamma-MSH are synthesized in the pituitary gland by the processing of a 32,000-molecular weight (MW) polypeptide called proopiomelanocortin (POMC). The existence of a further precursor (pre form) to POMC containing an additional N-terminal 'leader' peptide has been suggested by analysis of the in vitro translation products of poly(A)-containing RNA from AtT-20 cells, a mouse ACTH-producing cell line of pituitary origin. Nakanishi et al. cloned and sequenced a cDNA copy of the bovine prePOMC mRNA. This sequence confirmed the known structure of the carboxyl half of POMC and revealed the presence of a new MSH-like moiety, gamma-MSH, within the 16,000-MW amino half of the precursor (16K fragment). Recent experiments have suggested that this peptide may act in synergy with ACTH to increase corticosterone and aldosterone production in vivo and in vitro. We have now isolated from a rat genomic DNA library a segment of a DNA encoding most of POMC, using as probe a mouse 144-base pair cloned cDNA fragment encoding beta-MSH and beta-endorphin. The cloned rat gene is one of two (or more) closely related POMC genes. The DNA sequence obtained shows that the cloned POMC gene is not interrupted by any intervening sequence (IVS) between the codon for amino acid 19 and the presumptive poly(A) addition site. This region of POMC encodes all the biologically active peptides mentioned above. The DNA sequence encoding the putative gamma-MSH and the coding sequence that precedes it are highly conserved between rat and cow. This may indicate an as yet unrecognized biological function(s) for the NH2-terminal portion of the 16K fragment.

Adrenocorticotropic Hormone↗
PubMed1980

Different pattern of codon recognition by mammalian mitochondrial tRNAs.

Analysis of an almost complete mammalian mitochondrial DNA sequence has identified 23 possible tRNA genes and we speculate here that these are sufficient to translate all the codons of the mitochondrial genetic code. This number is much smaller than the minimum of 31 required by the wobble hypothesis. For each of the eight genetic code boxes with four codons for one amino acid we find a single specific tRNA gene with T in the first (wobble) position of the anticodon. We suggest that these tRNAs with U in the wobble position can recognize all four codons in these genetic code boxes either by a "two out of three" base interaction or by U.N wobble.

Animals↗
PubMed1979

A different genetic code in human mitochondria.

Comparison of the human mitochrondial DNA sequence of the cytochrome oxidase subunit II gene and the sequence of the corresponding beef heart protein shows that UGA is used as a tryptophan codon and not as a termination codon and suggests that AUA may be a methionine and not an isoleucine codon. The cytochrome oxidase II gene is contiguous at its 5' end with a tRNAAsp gene and there are only 25 bases at its 3' end before a tRNALys gene. These tRNA'S are different from all other known tRNA sequences.

Aspartic Acid↗
PubMed1978

Effect of gonadal steroids on the luteinizing hormone and follicle-stimulating hormone response to 8-bromo-adenosine 3',5'-monophosphate in anterior pituitary cells in culture.

-8-Bromo-cAMP stimulated the release of LH (approximately 20-fold) and FSH (approximately 2-fold) in control rat anterior pituitary cells in primary culture. 8-Bromo-cAMP-induced LH release was 2-3 times greater in cells preincubated for 48 h in the presence of 10(-8) M 17 beta-estradiol (E2). The LH response to 10(-10) M LHRH was similarly increased by E2 pretreatment whereas progesterone (P), which had no effect on the response to 8-bromo-cAMP, led to a reduction of the stimulatory effect of E2 on the LH response to the neurohormone. Preincubation with 10(-8) M testosterone (T) decreased the LH response to 8-bromo-cAMP by about 40%, whereas the response to LHRH was 80% inhibited. 8-Bromo-cAMP-induced FSH release was slightly increased in cells preincubated with E2 but was greatly augmented in cells treated with E2 + P. Basal FSH release was slightly increased (40%) after preincubation with P or T whereas the response to 8-bromo-cAMP was not significantly affected. The sensitivity of the FSH response to LHRH was increased by E2 whereas P and T led to a stimulation of the maximal FSH response to LHRH with no significant effect on the LHRH ED50 value. The present data indicate that P and E2 exert their effects on LH and FSH release at steps before and after cAMP formation, respectively. T appears to act at both steps on the release of the two gonadotropins.

Animals↗
PubMed1978

[Specific role of sex steroids on the pituitary level. Sex steroids and anterior pituitary secretion].

Although sex steroids were known to play a role in the control of LH, FSH, TSH and prolactin secretion, in vivo experiments could not discriminate between hypothalamic and pituitary sites of action. In this study, the specific action of sex steroids at the anterior pituitary level could be achieved using rat adenohypophyseal cells in primary culture. While estrogens stimulated the sensitivity of the LH and FSH responses to LHRH, androgens had differential effects on the secretion of the two gonadotropins: marked inhibition of LH and stimulation of FSH secretion. Progesterone, on the other hand, while having no effect in the absence of estrogens, could reverse the stimulatory effect of estrogens on LH release while it led to a stimulation of FSH secretion. Estrogens and thyroid hormone exert respective stimulatory and inhibitory effects on TSH secretion by a direct action at the pituitary level. These effects appear to be mediated changes of the level of adenohy-pophyseal TRH receptors. A close correlation was observed between the specificity of binding of the dopamine agonist (3H)dihydroergocryptine and the control of prolactin release in cells in culture, thus supporting the physiological importance of the dopamine receptor in the control of prolactin release. The high degree precision of this system permits assessment of activity of not only dopamine agonists and antagonists, but also of compounds having mixed agonist-antagonistic activity. Preincubation of anterior pituitary cells with 17beta-estradiol not only stimulated basal and TRH-induced prolactin release but, more unexpectedly, led to an almost complete reversal of the inhibitory effect of dopamine agonists on prolactin secretion. Besides its own interest, the adenohypophyseal cell culture system could well be used as a model system for study of the interaction between estrogens and dopaminergic action.

Androgens↗