Tissue-specific regulation of pituitary proopiomelanocortin gene transcription by corticotropin-releasing hormone, 3',5'-cyclic adenosine monophosphate, and glucocorticoids

The release of pituitary hormones derived from POMC is under multihormonal and tissue-specific control in the anterior and intermediate lobes of the pituitary where the same single-copy POMC gene is expressed. In order to assess the tissue-specificity of POMC regulation at the gene level, we have previously shown that glucocorticoids inhibit POMC gene transcription in the anterior but not in the intermediate pituitary. In the present work, we have investigated the role of corticotropin-releasing hormone (CRH) and cAMP in the differential regulation of anterior and intermediate pituitary POMC gene transcription. Using pituitary cells in primary culture and nuclear run-on transcription assays, we found that cAMP increases POMC gene transcription rate to the same extent in both anterior and intermediate pituitary cells while CRH only increases anterior pituitary POMC transcription rate. This observation contrasts with the stimulation of ACTH and alpha MSH release from anterior and intermediate pituitary cells, respectively, by both CRH and cAMP. In the anterior pituitary, both CRH and cAMP stimulated as well as basal POMC transcription rates are inhibited by glucocorticoids. In the anterior pituitary, both CRH stimulation and glucocorticoid inhibition of POMC transcription are rapid and do not require de novo protein synthesis. Thus, we report that transcription of the POMC gene is differentially regulated by CRH, cAMP, and glucocorticoids in anterior and intermediate pituitary tissues, in much the same way as the control of POMC processing and release.

A program for the graphic representation and manipulation of DNA sequences

We have developed a program for the graphic representation and manipulation of DNA sequences. The program (named CARTE from the French for 'map') is intended as a tool in the planning and analysis of recombinant DNA experiments. DNA sequences are represented as standard restriction maps, using any desired combination of restriction enzymes. Features of interest, such as promoters or coding sequences, can be highlighted. The sequence can be manipulated to mimic cloning, using deletions, insertions or replacements at specified sites. This process is facilitated by the simultaneous display of a graphic map of the entire sequence, a detailed picture of the work in progress, and a menu of functions.

Thyroid hormone stimulates rat pro-natriodilatin mRNA levels in primary cardiocyte cultures

Pro-natriodilatin (PND) is the precursor for atrial natriuretic peptide (ANP), a hormone which plays an important role in cardiovascular homeostasis. Since the effects of thyroid hormone (T3) on the cardiovascular and renal systems appear to mimic those elicited by ANP, we studied the effect of T3 on PND gene expression using rat neonatal cardiocytes in primary cultures. Treatment of cardiocytes for 48 h with T3 (5 X 10(-9) M) results in a maximal increase in PND mRNA levels; this increase is two fold in atrial and four fold in ventricular cell cultures. These results taken together with a previous report showing decreased plasma ANP in hypothyroid and increased plasma ANP in hyperthyroid rats suggest that at least some of the cardiovascular and renal effects of T3 may be mediated by a T3-dependent increase in PND gene expression.

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The physicians on staff at the Family Medicine Unit of the Medical Centre of Laval University evaluated the quality of medical treatment by a method of control involving objective criteria. This study is based on 88 entries in the medical records of patients who were seen for the dispensing of oral contraceptives. The information contained in these entries was compared to criteria published in the 1985 Canadian Report on Oral Contraceptives. On average, each record contained 60%-80% of the criteria, depending on the type of visit. For each criterion analysed separately, the proportion of entries corresponding to the norm varies between 6% and 95%. Overall, the quality of the entries is good. The standard to be attained is correspondence with the recommendations set out in the 1985

Glucocorticoid inhibition of transcription from episomal proopiomelanocortin gene promoter

Glucocorticoid hormones alter transcription of specific genes. Glucocorticoid-stimulated genes have been especially useful in unraveling molecular events responsible for positive gene regulation in mammals. The gene encoding proopiomelanocortin (POMC), which is under feedback inhibition by glucocorticoids, provides a model system to study negative gene regulation. Using an episomal bovine papilloma virus vector, we now demonstrate that a 769-base-pair fragment containing the rat POMC promoter is sufficient to confer glucocorticoid inhibition. Transcription from the episomal POMC promoter starts at the same site and is inhibited by glucocorticoids to the same extent as POMC transcription in the anterior pituitary. Glucocorticoid inhibition is specific for POMC transcripts; neither bovine papilloma virus nor cellular actin mRNAs are affected by glucocorticoids. Thus, the episomal bovine papilloma virus/POMC system can be used to study the relationship between negative regulation of POMC transcription and chromatin structure.

TaqI polymorphism at the 3' end of the human pronatriodilatin gene (hPND)

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XhoI polymorphism at the human pronatriodilatin (hPND) gene locus

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Expression of atrial natriuretic factor gene in heart ventricular tissue

A novel peptide hormone, atrial natriuretic factor (ANF), was recently isolated and characterized in mammalian atria. This hormone has potent natriuretic diuretic and vasorelaxant activities. Since ANF bioactivity was initially found in atria but not in ventricles, it was assumed that the ANF gene is specifically expressed in atria. We now report that ANF mRNA is present in ventricular tissue as well as in atria. This is clearly demonstrated by in situ hybridization and by Northern blot analysis. Rat ventricular ANF mRNA concentration is a hundred-fold lower than in atria. As in atria, the 126 amino acids precursor form of ANF is predominant in ventricles and it is present at a thousand-fold lower concentration. The ten-fold discrepancy in the ratio of ANF mRNA to immunoreactivity between atria and ventricles could reflect a higher rate of peptide release in the latter. Thus, ventricular ANF production may be physiologically significant in view of the much larger ventricular mass.

Characterization of reticulofibroblastoid colonies (CFU-RF) derived from bone marrow and long-term marrow culture monolayers

The maintenance of hemopoietic precursors in long-term liquid bone marrow cultures (LTBMC) is associated with the presence of an adherent stromal layer composed of heterogeneous cell populations. We have used a culture assay to promote the growth of one of its cellular components and characterize its properties. Freshly obtained bone marrow cells and cells derived from the adherent layer of LTBMC were grown in methylcellulose-clotted plasma in the presence of phytohemagglutinin-stimulated leukocyte-conditioned medium (PHA-LCM), hydrocortisone (HC), and citrated normal human plasma. Both sources contained cells (CFU-RF) that gave rise to colonies of cells with a reticulofibroblastoid appearance. In the presence of HC, most colonies contained lipid-laden cells. Colonies could be further propagated as adherent layers when transferred into liquid cultures. These cells produced laminin, fibronectin, and collagen types I, III, IV, and V. They were negative for Von Willebrand factor VIII. The ability to synthesize laminin and collagen type IV distinguished these cells from a population of previously described bone marrow fibroblasts (CFU-F). The relationship of CFU-RF to hemopoietic precursors was investigated using patients with chronic myeloid leukemia and bone marrow transplant recipients. Cells within CFU-RF-derived colonies were uniformly negative for the Philadelphia chromosome, thus making it unlikely that they belonged to the malignant hemopoietic clone. CFU-RF-derived colonies in bone marrow transplant recipients were found to be exclusively of host origin. Both observations support the view that CFU-RF is not part of the repertoire of hemopoietic stem cells.

Structure of the rat pro-opiomelanocortin (POMC) gene

The gene encoding pro-opiomelanocortin (POMC) presents unique regulatory features. In particular, glucocorticoids inhibit transcription of the POMC gene in the anterior pituitary, but not in the intermediate pituitary. In order to study the mechanism leading to transcriptional inhibition of POMC by glucocorticoid and the interaction of the glucocorticoid receptor complex with specific DNA sequences along the POMC gene, we have cloned the rat POMC gene and determined its structure. The gene is composed of three exons and appears to be present at a single copy per haploid genome. Besides the usual regulatory signals like 'TATA' and 'CCAAT' boxes, the upstream region contains sequences homologous to known enhancer sequences and to the glucocorticoid receptor binding site observed in glucocorticoid-responsive genes.

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.

The gene for rat atrial natriuretic factor

Atrial natriuretic factor (ANF), a peptide hormone recently isolated from heart atria, appears to play an important role in the regulation of extracellular fluid volume and blood pressure. Indeed, natural and synthetic ANF rapidly and markedly stimulate natriuresis and diuresis and produce smooth muscle relaxation. Consistent with the hypothesis that ANF is a novel hormone, it was recently shown that ANF is present in circulation, and high affinity membrane receptors specific for ANF have been described in renal, vascular, and adrenal tissues. These important biological activities suggest that conditions like hypertension could be associated with defective ANF gene expression. We and others have shown by cDNA cloning that ANF is part of a larger precursor, pro-natriodilatin (PND). We now describe the isolation and structural analysis of the rat PND gene. Southern blot analysis of rat genomic DNA suggests the presence of a single PND gene per haploid genome. The PND coding sequences are interrupted by two short introns. A long alternating purine-pyrimidine tract (GT)9GATG(GT)27 is found 111 base pairs downstream of the polyadenylation site; such sequences could adopt Z-DNA configuration and they have been associated with sequences that appear very active in intergenic recombination. Comparison of the rat and human PND genomic sequences shows highest homology in 5'-flanking as well as in coding sequences. The rat PND gene will be a useful model to study the physiology and pathology of this important regulator of the cardiovascular system.

Opposite regulation of pro-opiomelanocortin gene transcription by glucocorticoids and CRH

Pro-opiomelanocortin (POMC) is the pituitary precursor for adrenocorticotropin (ACTH), beta-endorphin, beta-lipotropin and the melanotropins. The level of ACTH secretion from the anterior pituitary is largely determined by the competing action of the stimulatory hypothalamic hormone, corticoliberin (corticotropin-releasing hormone, CRH), and the inhibitory effect of glucocorticoids. We now demonstrate that these two hormones, glucocorticoids and CRH, also inhibit and stimulate, respectively, the transcription rate of the POMC gene as measured by nuclear run-on transcription assays. Indeed, we show both by in vivo treatment and with rat anterior pituitary cells in primary culture that glucocorticoids inhibit within 30 min transcription of the POMC gene. Similarly, we find that CRH stimulates POMC gene transcription within 15 min. CRH and glucocorticoids can compete with each other to set the rate of POMC transcription. Our results indicate that CRH and glucocorticoids regulate anterior pituitary POMC gene transcription in addition to their well-documented role in the control of POMC peptide release.

Plasmodium falciparum malaria mimicking autoimmune hemolytic anemia during pregnancy

A 30-year-old woman contracted Plasmodium falciparum malaria in the first trimester of her pregnancy while taking chloroquine for malaria prophylaxis. Her illness was characterized by hemolytic anemia with IgG1 coating of the surface of the erythrocytes and IgG3 in her serum. The hemolysis subsided following treatment of the malaria infection early in the third trimester. She delivered at term an infant who had hypoplasia of the right tibia and fibula and absence of the fifth ray of the right foot. The hemolytic process was attributed to the malaria infection, and the birth defect may have been related to the antimalarial therapy in the first trimester of pregnancy.

Gene structure of human cardiac hormone precursor, pronatriodilatin

Atrial cardiocytes contain granules typical of protein-secreting cells, and atrial extracts are known to contain a powerful natriuretic and diuretic activity and to possess smooth muscle relaxant activity. A variety of active atrial peptides have been isolated, including a family of related peptides showing natriuretic, diuretic and smooth muscle relaxant activities in rat and human atria; these peptides were named atrial natriuretic factor (ANF). Another unrelated peptide from pig atria, cardiodilatin, is thought to possess only smooth muscle relaxant activity. Its partial amino acid sequence shows no homology with ANF sequences. The sequence analysis of a large form (106 amino acids) of ANF and of ANF complementary DNA clones indicates that cardiodilatin and ANF peptides are synthesized from a common precursor. This precursor also contains a signal peptide sequence expected of a secretory protein. We now describe the complete structure and sequence of the human gene for this novel hormone precursor that we call pronatriodilatin.

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.

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.

Intensive plasma exchange therapy in ten patients with idiopathic thrombocytopenic purpura

Intensive plasma exchange therapy with fresh-frozen plasma as the replacement fluid was used to manage ten patients, five with acute and five with chronic immune thrombocytopenic purpura (ITP). Therapy was started because of severe hemorrhage (1 case), failure to respond to steroid therapy (6 cases), or steroid dependence (3 cases). After a median of four exchanges over 6 days (median total volume removed, 11.7 liters), initial responses, defined as a platelet count greater than 100,000 per microliter at the end of the exchange series, were observed in 80 percent of the patients treated. Two adolescents, ages 16 and 17 years, with chronic ITP failed to respond to plasma exchange therapy and subsequently responded to splenectomy. Prolonged remissions of 9 months and greater than 2 years were observed in two patients with acute ITP; in patients with chronic ITP, no prolonged remissions occurred. Neither pre-exchange levels of platelet-associated immunoglobulin G (PAIgG) nor circulating immune complexes predicted the response to plasma exchange, although serially determined PAIgG levels correlated with the severity of ITP and response, or lack of response, to plasma exchange. We conclude that intensive plasma exchange merits further study in patients with acute ITP unresponsive to steroid therapy to determine if the need for splenectomy is reduced. In selected patients with chronic ITP, exchange therapy may provide short-term adjunctive benefit.

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.

Women and work: the more, the better?

An increasing number of women work outside the home, and one might think that the resulting strain would have an adverse effect on women's health. However, studies conducted up to now have disclosed no evidence of harm. Rather, working outside the home often appears to benefit women. However, such results could be due to the `healthy worker effect', whereby the least healthy people do not enter the work force in the first place. When their skills are underutilized and superiors are indifferent to their accomplishments, women show as much vulnerability to stress as men do. Far more research is needed to confirm or disprove these preliminary results, and to understand the various factors involved.

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.