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Biomedical subjects

J Philippe

Publications and source records attributed to J Philippe.

At least 91 records · Page 5Linked to original sources
PubMed1995

[Occupational exposure and malignant hemopathies: a case-control study in Lyon (France)].

A hospital based case-control study was carried out in Lyon with the aim of assessing the association between haematologic malignancies and occupational exposures to 320 compounds. Job histories were obtained by questionnaire for 118 cases (52 non Hodgkin lymphomas, 48 acute myeloid leukemia, 18 others leukaemias), and 118 controls with diseases other than cancer from the same general hospital; controls were matched for sex, age and nationality. Systematic coding of exposures based on a blind analysis of job histories, was done by a team of experts in chemistry and occupational health. Mantel-Haenszel analysis was performed. Significantly elevated odds-ratio were observed for non Hodgkin lymphomas and exposure to mineral oils (14.86; 2.76-80.0), excavation dusts (3.91; 0.94-15.95), alkali compounds (2.90; 1.09-7.68), inks (2.47; 1.09-5.17). For inks, a dose-response relation was observed. Elevated odds-ratios appeared for acute myeloid leukaemias and arsenic compounds (3.02; 0.90-10.13) and lead compounds (3.70; 1.09-13.44). When regarding industrial activities, two of them are more frequently found: food industries (14 cases/5 controls), public works (12 cases/0 control). When regarding jobs, winding (6 cases/0 control), glass workers (8 cases/1 control) and warehousemen (10 cases and 4 controls) are more often seen among cases.

Adult↗
PubMed1995

[Malignant non-Hodgkin lymphoma of cardiac localization. Apropos of a case].

Malignant non-Hodgkin's lymphomas are rare in the absence of human immunodeficiency virus infection and it is exceptional for a cardiac site to be the prominent feature. In our case, the malignant lymphoma was revealed by pericardial effusion in a context of alteration of the general state. Echocardiography revealed a heterogeneous mass in the right atrium and an abundant circumferential pericardial effusion. Thoracic computed tomography allowed local staging and magnetic resonance imaging (MRI) allowed a better definition, than CT scan, of the extension of the tumour into the various cardiac structures. The histological diagnosis was established on biopsy of a mediastinal lymph node. The patient died 7 months after the diagnosis, despite chemotherapy. The authors emphasize the contribution of echocardiography in the diagnosis of cardiac tumours, computed tomography in local staging, and MRI in the analysis of the various cardiac structures.

Heart Neoplasms↗
PubMed1995

[Systemic cholesterol embolism].

The authors report two cases of cholesterol embolism and review the literature on this subject. Cholesterol crystal emboli are very serious complication of atheroma, generally situated in the aorta and usually in patients in their sixties. The frequency of cholesterol embolism is 20% in autopsy studies in this population. The embolic process accounts for the polymorphic clinical feature. Clinical signs are always delayed in relation to triggering factors. The symptoms can sometimes simulate a systemic disease. Cutaneous signs are present in 40 to 75% of cases. Acute renal failure is present in 30% of cases. Other signs may also be observed: alteration of the general state, fever, neurological disorders, pain of the lower limbs, myalgia, gastrointestinal haemorrhage or perforation, ischaemic colitis, pancreatitis, mesenteric or coronary angina. A triggering factor is revealed in 80% of cases: aortic surgery, retrograde aortic catheterization, fibrinolysis or oral anticoagulant treatment. The prognosis is poor due to the clinical context, the patient's age and the absence of any specific treatment. The short-term mortality is 60 to 80% according to various series. The best treatment is prevention: carefully assess the indication for an endovascular procedure in an atheromatous patient; if necessary, perform transoesophageal ultrasonography to evaluate the risk; whenever possible change the incision in vascular investigations or operative procedures in high-risk patients.

Aged↗
PubMed1994

Ablation of islet endocrine cells by targeted expression of hormone-promoter-driven toxigenes.

Ontogenic relationships between the different types of endocrine cells in the islets of Langerhans were explored by generating transgenic mouse embryos in which cells transcribing the glucagon, insulin, or pancreatic polypeptide genes were destroyed through the promoter-targeted expression of the diphtheria toxin A chain. Embryos lacking glucagon- or insulin-containing cells did not exhibit alterations in the development of the nontargeted islet cell types, whereas embryos lacking pancreatic polypeptide gene-expressing cells also lacked pancreatic insulin- and somatostatin-containing cells. These results show that neither glucagon nor insulin gene-expressing cells are essential for the differentiation of the other islet endocrine-cell types. These results also suggest that pancreatic polypeptide gene-expressing cells are indispensable for the differentiation of islet beta and delta cells because the former produce a necessary paracrine or endocrine factor and/or operate through a cell-lineage relationship.

Animals↗
PubMed1994

Functional coupling between the cyclic adenosine monophosphate pathway and cholecystokinin secretion in RIN cells.

The cellular events associated with cAMP-dependent cholecystokinin (CCK) release were investigated with an X-ray induced rat pancreatic tumor cell line (RIN 1056 E). Forskolin dose-dependently stimulated the release of CCK. Agents that increase [Ca2+]i (thapsigargin, Bay K 8644, ionomycin) also stimulated the release of CCK. Conversely, absence of extracellular Ca2+ or cell treatment with various calcium channel blockers strongly reduced the forskolin-induced CCK release. Finally, the cAMP-kinase inhibitor H89, the calmodulin antagonist W7 and the Ca/calmodulin-dependent protein-kinase II inhibitor KN62 strongly inhibited the forskolin-evoked CCK secretion. We conclude that the release of CCK via a cAMP-dependent pathway is dependent on the activation of voltage-dependent calcium channels and may implicate protein kinase A, calmodulin and the Ca/calmodulin-dependent protein kinase II.

Adenoma, Islet Cell↗
PubMed1994

Glucagon gene expression is negatively regulated by hepatocyte nuclear factor 3 beta.

Pancreatic expression of the glucagon gene depends on multiple transcription factors interacting with at least three DNA control elements: G1, the upstream promoter element, and G2 and G3, two enhancer-like sequences. We report here that the major enhancer of the rat glucagon gene, G2, interacts with three protein complexes, A1, A2, and A3. A2 is detected only in islet cells, and impairment of its binding to mutant G2 causes a marked decrease in transcriptional activity. We identify A1 as hepatocyte nuclear factor 3 beta (HNF-3 beta), a member of the HNF-3 DNA-binding protein family found in abundance in the liver which has been proposed to play a role in the formation of gut-related organs. HNF-3 beta binds G2 on a site which overlaps A2 and acts as a repressor of glucagon gene expression, as demonstrated by mutational analyses of G2 and by cotransfection of HNF-3 beta cDNA along with reporter genes containing G2 into glucagon-producing cells. Our data implicate HNF-3 beta in the control of glucagon gene expression and strengthen the idea of endodermal origin of the islet cells.

Animals↗
PubMed1994

cis-regulatory elements and trans-acting factors directing basal and cAMP-stimulated human renin gene expression in chorionic cells.

Much knowledge was accumulated in the regulation of plasma renin activity and renin secretion during recent years. However, the mechanisms of renin gene transcription, especially for the human gene, have been poorly studied because of the lack of cell lines expressing renin. Cells derived from chorion tissue were used to study renin gene transcription because these cells express renin and regulate renin secretion in a similar way to JG cells. The present study was performed to determine the cis-regulatory elements and the trans-acting factors involved in human renin gene expression using chorionic cells. Transient DNA transfections were performed with various constructs containing the 5'-flanking region of the human renin gene. 5'-Deletion analysis of the human renin promoter (from -2616 to -67 bp) revealed the presence of two proximal negative cis-regulatory elements between -374 and -273 bp and between -273 and -137 bp. These elements were not present in a non-renin-producing cell line, JEG-3 cells. DNase I footprinting revealed that two sequences located within these regions bind trans-factors present in chorionic cellular nuclear extract: AGE3-like sequence (-293/-273) and apolipoprotein A1 regulatory protein-1-like sequence (-259/-245). The first 110 bp of the renin promoter were sufficient to direct specific expression in chorionic cells and contained two footprints sharing homology with ets (-29/-6) and pituitary-specific factor (Pit-1) (-70/-62) sequences. Furthermore, one footprint (-234/-214) contained the sequence TAGCGTCA, which shares strong homology to the cAMP-responsive element (CRE) binding site. Gel shift analysis showed specific DNA/protein complexes within this region, which were displaced by the somatostatin consensus CRE. Finally, luciferase analysis of 5'-deletion mutant revealed that -273 to +16 bp of the renin promoter was sufficient to confer complete forskolin stimulation, whereas deletion to -130 (deletion of the CRE) decreased cAMP responsiveness by 50% and those to -67 bp (deletion of the CRE and Pit-1-like sequences) suppressed it. Thus, these latter two sequences probably act together to confer complete cAMP responsiveness.

Base Sequence↗
PubMed1994

Insulin gene transcription is decreased rapidly by lowering glucose concentrations in rat islet cells.

Glucose is the main physiological regulator of insulin biosynthesis and secretion. To exert an effect on biosynthesis, stimulatory concentrations of glucose act on insulin gene expression at both transcriptional and posttranscriptional levels. The relative importance of these two effects is controversial. Studies on the effect of decreasing glucose concentrations in vitro have been contradictory as to its rapidity and magnitude. We have investigated whether a decrease in glucose concentrations from a stimulatory (11 mM) to a nonstimulatory (2 mM) level regulates insulin gene expression in both isolated rat islets and INS-1 cells, an insulinoma-derived cell line that retains a number of the differentiation characteristics of native beta-cells. We show that, in the presence of a nonstimulatory concentration of glucose, insulin mRNA levels decrease rapidly in both rat islets and INS-1 cells. Low glucose decreases insulin gene expression at the transcriptional level, and this effect is mediated by DNA sequences present within 254 base pairs of the 5'-flank of the rat insulin I gene. We conclude that lowering glucose from 11 to 2 mM decreases insulin mRNA rapidly by a transcriptional effect.

Animals↗
PubMed1993

Regulation of human renin secretion and renin transcription by quantitative PCR in cultured chorionic cells: synergistic effect of cyclic AMP and protein kinase C.

A quantitative PCR was developed to measure human renin mRNA in chorionic cells under various stimuli. An internal standard consisting of a mutated renin mRNA with an insertion of 60 bp was designed to quantify the reaction. Quantitative PCR is a suitable tool for studying human renin gene transcription from a low number of cells. Forskolin alone had no effect on either renin mRNA levels or renin production whereas 10(-7)M PMA stimulated renin mRNA levels and renin production 5- and 2.6-fold, respectively, after 24 hours incubation. PMA and forskolin acted synergistically to increase both renin mRNA levels and renin production in a dose-dependent manner.

Base Sequence↗
PubMed1993

Somatostatin inhibits insulin-gene expression through a posttranscriptional mechanism in a hamster islet cell line.

Insulin secretion is regulated by the interplay of nutrients, local intraislet factors, and hormones. Nutrients involved in the positive control of insulin secretion, such as glucose and amino acid, also act on insulin biosynthesis. SRIF is one of the most potent inhibitors of insulin secretion. To determine whether SRIF also regulates insulin biosynthesis, we studied its effects on insulin-gene expression. SRIF decreases steady-state insulin mRNA levels in a clonal hamster islet cell line, HIT-T15, in a dose- and time-dependent manner; this decrease does not occur at the transcriptional level but essentially at a posttranscriptional level. We conclude that SRIF not only modulates insulin secretion but also affects insulin-gene expression.

Animals↗
PubMed1992

Thyroid emergencies.

Thyroid storm is a rapid decompensation of severe hyperthyroidism which can best be described by the three criteria of hyperthermia, tachycardia and altered mental state with severe agitation. There has to be a precipitating factor such as infection, iodine contamination, surgery or even I-131 treatment. Severe hyperthyroidism not fulfilling the criteria of thyroid storm can also be an indication for emergency treatment, particularly in the elderly with heart disease. Suppressed serum TSH and elevated free T4 levels are essential to confirm the diagnosis. When rapidly available, radioiodine uptake of the thyroid can be useful. Therapy aims at rapidly reducing the active circulating hormone pool, hypermetabolic state, tachycardia, and finally hormone synthesis. Thyroid secretion can be blocked by ioipanoic acid or ipodate while hypermetabolic state can be reduced with beta-blockers or calcium channel-blockers. Treatment of hyperthyroidism in patients with iodine contamination is a real therapeutic challenge. Myxoedema coma, a complication of severe hypothyroidism, is defined by hypothermia (rectal temperature less than 36 degrees C), bradycardia, slow mentation, precipitating factor such as infection or drug overdose, and increased serum creatine phosphokinase levels. Diagnosis of severe hypothyroidism should be confirmed by serum measurements of TSH and free T4. Treatment consists of general supporting measures including rewarming, correction of serum electrolyte disturbances, and adequate alimentation. Thyroid hormone treatment should initially be aggressive using either 300-400 micrograms of T4 or 20-40 micrograms of T3 intravenously. Cortisone therapy may be added. Patients should be under close monitoring as arrhythmias and myocardial infarction are frequent complications of myxoedema coma and/or its treatment with thyroid hormones.

Acute Disease↗
PubMed1992

APUDomas: acute complications and their medical management.

APUDomas are rare tumours originating from a variety of endocrine cells localized in different organs. Acute complications from APUDomas usually result from the increased biosynthesis and release of bioactive amines or polypeptide hormones by the tumour. Less frequently, bleeding or compression by the tumour can occur requiring emergency surgery. Increased gastrin production by gastrinomas is the cause of ZES (peptic ulceration and diarrhoea) by gastrin effects on gastric acid secretion. Volume depletion, hypokalaemia, severe bleeding, duodenal perforation, oesophageal stricture and pyloric stenosis are the most dramatic complications. Treatment of these complications and their prevention has been facilitated by the availability of antagonists to H2 receptors and H(+)-K+ proton pump. These medications should control acid output in every patient with ZES. Frequent manifestations of carcinoid tumours, VIPomas and medullary thyroid carcinomas are flushing and diarrhoea. Octreotide, a long-acting somatostatin analogue, has markedly changed the management of these patients, their symptoms decreasing in severity or disappearing in most cases. Octreotide has also been used with success in the prevention and treatment of the carcinoid crisis, a dreaded complication of carcinoid tumours. A better understanding of the pathophysiology of APUDomas has enabled new treatment designs which have considerably ameliorated the quality of life of patients affected by these tumours; efforts must be continued to affect their life expectancy.

Acute Disease↗
PubMed1992

Cyclic adenosine monophosphate prevents the glucocorticoid-mediated inhibition of insulin gene expression in rodent islet cells.

Dexamethasone negatively regulates insulin gene expression in HIT-15 cells. In vivo, however, an excess of glucocorticoids results in an increase in insulin biosynthesis and peripheral hyperinsulinemia. To resolve this contradiction, we have studied the effects of dexamethasone in primary rat islet cells. We show here that dexamethasone decreases insulin mRNA levels in single islet cells, as in HIT-15 cells, but does not affect these levels in reaggregated islet cells and increases them in intact islets of Langerhans. Because cAMP is an important regulator of insulin gene expression and intracellular cAMP content may be decreased in single beta cells, we investigated whether cAMP could prevent the inhibitory effect of dexamethasone on insulin mRNA levels. In the presence of cAMP analogues, the inhibitory action of dexamethasone was not only prevented, but insulin mRNA increased to levels comparable to those observed when cAMP analogues were used alone. We conclude that the insulin gene is negatively regulated by dexamethasone in single islet cells, but that other factors such as cAMP prevent this effect when the native environment of islet cells is preserved. Our results indicate that insulin gene regulation is influenced by cell to cell contacts within the islet, and that intracellular cAMP levels might be influential in this regulation.

Animals↗