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Biomedical subjects

M Vernet

Publications and source records attributed to M Vernet.

At least 19 recordsLinked to original sources
PubMed2003

[Bilateral pneumothorax and tamponade after acupuncture].

INTRODUCTION: The "target" of acupuncture is usually the muscle, but it occasionally approaches other anatomical structures such as the pleura, which may subsequently suffer damage. OBSERVATION: During a session of acupuncture, a 25-year-old woman had a malaise with shock and neurological disorders. The initial examinations revealed a bilateral pneumothorax associated with pericardial and peritoneal effusions. Symptomatic reanimation combining dopamine, left pleural draining and pericardial puncture led to rapid haemodynamic improvement. The etiological exploration, having eliminated an underlying pathology, concluded in the diagnosis of tamponade and bilateral pneumothorax following a session of acupuncture. COMMENTS: Our patient presented the association of two traumatic complications of acupuncture: cardiac tamponade due to haemopericardium and bilateral pneumothorax. Although these complications are rare, they must be known.

Acupuncture Therapy↗
PubMed2003

[Fat embolism after total hip prosthesis replacement preserving the femoral stem].

Fat embolism is a known complication of traumatology, especially in long bone fractures. It may also occur in liposuction and articular surgery (0.1%). Fat embolic events are most often clinically insignificant and difficult to recognize since clinical manifestations are varied and there is no routine laboratory or radiographic diagnosis. Classically, fat embolism syndrome presents with the triad of pulmonary distress, mental status changes, and cutaneous manifestations. We report the case of a 33-year-old woman who developed acute respiratory distress 10 days after hip arthroplasty. Several aetiologies such as fibrinocruoric pulmonary embolism, pulmonary aspiration and bacterial pneumonia were discussed. Fat embolism was diagnosed, based on suggestive clinical manifestations, radiographic and laboratory findings, although fat embolism after hip arthroplasty without intramedullary pressurization is infrequent.

Adult↗
PubMed2003

Expression of thymidine kinase driven by an endothelial-specific promoter inhibits tumor growth of Lewis lung carcinoma cells in transgenic mice.

The possibility of inhibiting tumor growth by limiting angiogenesis has raised considerable interest. In this study, we examined the feasibility of inhibiting tumor growth by targeting a suicide gene in the endothelium. Toxicity must be directed solely to angiogenic cells. Therefore, we used the herpes simplex virus-thymidine kinase (TK) gene, in combination with the prodrug ganciclovir (GCV), which affects replicative cells. To test this strategy, we produced transgenic mice carrying the TK gene driven by the vascular endothelial (VE)-cadherin promoter. Lewis lung carcinoma cells were injected subcutaneously to establish tumors and to test the effect of GCV on tumor growth. In two independent transgenic lines, GCV treatment (75 mg/kg/day) resulted in a 66-71% reduction of tumor volume at day 20 postimplantation compared to wild-type mice (650 and 550 versus 1930 mm(3), P<0.02 and 0.01, respectively), whereas no significant difference was observed when vehicle alone was injected. Tumor growth inhibition was accompanied by a marked reduction in tumor vascular density (151 versus 276 vessels/mm(2), P<0.05) and an increase in tumor cell death, suggesting that tumor growth inhibition was caused by a reduction in tumor angiogenesis. Our data support the potential utility of endothelial targeting of suicide genes in cancer therapy.

Animals↗
PubMed2001

Hypopituitarism after surgical clipping of a ruptured cerebral aneurysm.

OBJECTIVE: The causes of hypopituitarism in adult life are most frequently cerebral tumors, pituitary infarction, head trauma, pituitary surgery, or irradiation. We report a case of hypopituitarism after surgical clipping of a ruptured cerebral aneurysm. Two previous cases after the rupture of a cerebral aneurysm have been reported. DESIGN: Case report. PATIENTS: One 42-yr-old man. MEASUREMENTS AND MAIN RESULTS: A 42-yr-old man was admitted as an emergency for unconsciousness. The computed tomography showed a massive subarachnoid hemorrhage, and specific angiography showed an aneurysm in the internal carotid. The aneurysm was successfully clipped through craniotomy. The patient's hospital course was marked by a few episodes of pulmonary infection, and a tracheotomy was performed. The patient was transferred to the rehabilitation unit; he received a rating of 9 on the Glasgow Coma Scale. Seven months after rupture of the aneurysm, the patient was readmitted to the intensive care unit for septic shock, with pulmonary infection associated with vomiting and diarrhea. Despite standard therapy and inotropic support, there was no improvement of his clinical condition. Adrenal failure was then suspected. Treatment was started immediately with hydrocortisone (50 mg) four times a day. Within hours, his clinical condition improved. The following month, the patient was weaned off his tracheotomy and had nearly recovered. Endocrine tests confirmed the cortisol insufficiency but also hypothyroidism and hypogonadotropic hypogonadism secondary to hypopituitarism. CONCLUSION: Our case is the first one reported of hypopituitarism after surgical clipping of a ruptured cerebral aneurysm.

Adult↗
PubMed2001

Could heart rate variability predict outcome in patients with severe head injury? A pilot study.

Despite major improvements in the resuscitation of patients with head injury, the outcome of patients with head trauma often remains poor and difficult to establish. Heart rate variability (HRV) analysis is a noninvasive tool used to measure autonomic nervous system (ANS) activity. The aim of this prospective study was to investigate whether HRV analysis might be a useful adjunct for predicting outcome in patients with severe head injury. Twenty patients with severe head trauma (Glasgow Coma Scale [GCS] or= 10) to HRV in patients characterized by a worsened neurologic state (GCS < 10). Statistical analysis used the Kruskal-Wallis test, P < .05. To assess whether HRV could predict evolution to brain death, receiver operating characteristic (ROC) curves were generated the day after trauma for Total Power, natural logarithm of high-frequency component of spectral analysis (LnHF), natural logarithm of low-frequency component of spectral analysis (LnLF), and root mean square for successive interval differences (rMSSD). Seven patients died between Day 1 and Day 5 after trauma. Six of those had progressed to brain death. In these six patients, at Day 1, Global HRV and parasympathetic tone were significantly higher. Referring to the area under the rMSSD ROC curve, HRV might provide useful information in predicting early evolution of patients with severe head trauma. During the awakening period, global HRV and the parasympathetic tone were significantly lower in the worsened neurologic state group. In conclusion, HRV could be helpful as a predictor of imminent brain death and a useful adjunct for predicting the outcome of patients with severe head injury.

Accidental Falls↗
PubMed2001

Single-cell gel/comet assay applied to the analysis of UV radiation-induced DNA damage in Rhodomonas sp. (Cryptophyta).

The single-cell gel/comet assay is an electrophoretic technique used to detect single-strand breaks in DNA. Damage is assessed examining individual cells under an epifluorescent microscope. UV-induced DNA damage consists mostly of the formation of pyrimidine dimers; therefore, most of the damage cannot be detected using a standard comet assay. The enzyme T4 endonuclease V breaks DNA strands at sites of pyrimidine dimers. The main objective of this work is to evaluate the comet assay to detect UV-induced damage in DNA after an initial treatment of cells with T4 endonuclease V. This work was conducted on Rhodomonas sp. (Cryptophyta), a marine unicellular flagellate. Cells of Rhodomonas sp. were exposed to 12 h visible + ultraviolet-A + ultraviolet-B (VIS + UVA + UVB) and VIS (control), with and without T4 endonuclease V. Cells exposed to VIS + UVA + UVB showed approximately 200% more damage than control if these were treated with T4 endonuclease V. Rhodomonas sp. were exposed to 3, 6, 9 and 12 h of VIS, VIS + UVA and VIS + UVA + UVB. Damage induced by VIS + UVA + UVB as detected by the comet assay increased along with exposure time. However, damage caused by VIS and VIS + UVA remained relatively constant at all times. Results of this study indicate that the comet assay is more sensitive to UV radiation damage when used in conjunction with T4 endonuclease V. This modification of the comet assay can be used as an alternative technique to detect DNA damage in single cells caused by UV radiation.

Comet Assay↗
PubMed2000

[Assessment of iron status].

Biological tests useful for the assessment of iron status depend on the metabolic compartment to be explored. The transport compartment is explored by the measurement of serum iron, transferrin and its saturation; these tests still play a major role in the screening of iron overload. Assessment of stores is performed by the assay of serum ferritin either for diagnosing depletion or assessing overload. Falsely normal or increased results (inflammation, infection, cancer) can hide a true deficiency. Erythrocyte ferritin and glycosylated ferritin can be useful tools for the interpretation of hyperferritinemia. Soluble transferrin receptor is a specific marker of functional deficiency, not influenced by confounding pathologies.

Ferritins↗
PubMed2000

Difference between office and ambulatory blood pressure or real white coat effect: does it matter in terms of prognosis?

OBJECTIVE: The blood pressure (BP) response to the doctor's visit, generally referred as the white coat (WC) response, is usually estimated by the difference between office BP (OBP) and ambulatory BP (ABP). The purpose of this study was to determine the validity of this estimation. To that end, we compared the real WC effect and the estimated WC effect (OBP-ABP) in terms of magnitude and consequences on target organs. DESIGN: The study comprised 88 patients referred for hypertension. The real WC effect was measured using a Finapres device and expressed as the maximal WC effect (Max WC) or the average WC effect (Aver WC). For the estimation of target organ damages, the whole hypertensive group was separated into two groups according to the medians of the Aver WC, the Max WC, and the estimated WC effects, successively. Left ventricular mass index, E to A mitral wave ratio and pulse wave velocity were compared between groups as were serum creatinine, cholesterol and glucose levels. RESULTS: The estimated WC effect proved to be a bad index of the real response to the doctor's visit as assessed by their difference of magnitude between the two (20 +/- 17, 12 +/- 12 and 30 +/- 14 mmHg as estimated WC, Aver WC and Max WC effects, respectively), their loose correlations (r=0.31, P=0.004 between estimated WC and Aver WC effects; r=0.27, P=0.01 between estimated WC and Max WC effects), and finally by the fact that they were in agreement in less than two-thirds of the patients for the categorization of the WC response. Concerning target organ damages, no difference in terms of cardiac mass, diastolic function, arterial distensibility, renal function and cardiovascular risk profile could be discerned between the groups with a high and a low WC effect, either real or estimated, when age and ABP were taken into account. CONCLUSION: The present work supports the view that the true WC effect and its estimation are not equivalent. However, the way in which the WC response is defined does not alter its effect on target organs or cardiovascular risk profile.

Adult↗
PubMed2000

Assessment of iron status with a new fully automated assay for transferrin receptor in human serum.

Serum transferrin receptor is considered as a reliable marker of iron status particularly when iron deficiency is associated with chronic disorders such as inflammation, infection or malignancy. The present study aims to illustrate the performances of a new fully automated assay using immunonephelometry. The intra and between-assay precision was found to be very good (CVs < 4%). In healthy subjects there was no statistically significant difference between men and women. With a cut-off of 1.76 mg/l for diagnosing iron deficiency either alone or combined with anemia of chronic diseases, the sensitivity and specificity were respectively 82% and 96.8%. Unlike conventional biochemical and hematological tests, soluble transferrin receptor was unaffected by confounding pathologies. In genetic hemochromatosis the concentration of soluble transferrin receptor was mostly decreased due to the regulatory effect of iron intracellular level. Our study confirms the reliability of soluble transferrin receptor for the assessment of iron status. It is now possible to assay soluble transferrin receptor, ferritin and transferrin on the same apparatus within 15 minutes.

Chronic Disease↗
PubMed1999

The vascular endothelial-cadherin promoter directs endothelial-specific expression in transgenic mice.

Vascular endothelial-cadherin (VE-cadherin) is a calcium-dependent adhesive molecule, exclusively and constitutively expressed in endothelial cells. Analysis of the VE-cadherin promoter fused to a reporter gene in bovine aortic endothelial cells showed three major functional regions. The proximal region alone (-139, +24) promoted nonspecific transcription; the addition of the (-289, -140) and (-2226, -1190) domains abolished transcription in fibroblasts while expression in endothelial cells remained unchanged, suggesting that fragments (-2226, +24) and longer contain the full endogenous promoter activity. To study the transcriptional specificity of the promoter region in vivo, we generated transgenic mice carrying the chimeric construct containing the (-2486, +24) region. The promoter directed reporter expression in all examined organs of adult transgenic mice. During embryonic development, transgene expression was detected at the early steps of vasculogenesis. Later, the expression persisted during development of the vascular system and was restricted to the endothelial layer of the vessels. Together, these data provide evidence for specific regulatory regions within the VE-cadherin promoter. Furthermore, the identification of DNA sequences restricting gene expression to the endothelium has many potential applications for the development of animal models of cardiovascular or angiogenic diseases or for the delivery of therapeutic molecules.

5' Untranslated Regions↗
PubMed1999

Thermococcus barophilus sp. nov., a new barophilic and hyperthermophilic archaeon isolated under high hydrostatic pressure from a deep-sea hydrothermal vent.

A novel barophilic, hyperthermophilic, anaerobic sulfur-metabolizing archaeon, strain MPT (T = type strain), was isolated from a hydrothermal vent site (Snakepit) on the Mid-Atlantic Ridge (depth, 3550 m). Enrichments and isolation were done under 40 MPa hydrostatic pressure at 95 degrees C. Strain MPT was barophilic at 75, 80, 85, 90, 95 and 98 degrees C, and was an obligate barophile between 95 and 100 degrees C (Tmax). For growth above 95 degrees C, a pressure of 15.0-17.5 MPa was required. The strain grew at 48-95 degrees C under atmospheric pressure. The optimal temperature for growth was 85 degrees C at both high (40 MPa) and low (0.3 MPa) pressures. The growth rate was twofold higher at 85 degrees C under in situ hydrostatic pressure compared to at low pressure. Strain MPT cells were motile, coccoid, 0.8-2.0 microns in diameter and covered by a hexagonal S-layer lattice. The optimum pH and NaCl concentration for growth at low pressure were 7.0 and 20-30 g l-1, respectively. The new isolate was an obligate heterotroph and utilized yeast extract, beef extract and peptone for growth. Growth was optimal in the presence of elemental sulfur. Rifampicin and chloramphenicol inhibited growth. The core lipids consisted of a major archaeol and a complex lipid pattern consisting of a major phospholipid. The DNA G + C content was 37.1 mol%. Sequencing of the 16S rRNA gene revealed that strain MPT belonged to the genus Thermococcus and it is proposed that this isolate should be designated as a new species, Thermococcus barophilus.

Atlantic Ocean↗
PubMed1999

Methanococcus vulcanius sp. nov., a novel hyperthermophilic methanogen isolated from East Pacific Rise, and identification of Methanococcus sp. DSM 4213T as Methanococcus fervens sp. nov.

An autotrophic, hyperthermophilic methanogen (M7T) was isolated from a deep-sea hydrothermal chimney sample collected on the East Pacific Rise at a depth of 2600 m. The coccoid-shaped cells are flagellated and exhibit a slight tumbling motility. The temperature range for growth at pH 6.5 was 49-89 degrees C, with optimum growth at 80 degrees C. The optimum pH for growth was 6.5, and the optimum NaCl concentration for growth was around 25 g l-1. The new isolate used H2 and CO2 as the only substrates for growth and methane production. Tungsten, selenium and yeast extract stimulated growth significantly. In the presence of CO2 and H2, the organism reduced elemental sulphur to hydrogen sulphide. Growth was inhibited by chloramphenicol and rifampicin, but not by ampicillin, kanamycin, penicillin and streptomycin. The G + C content of the genomic DNA was 31 mol%. As determined by 16S rDNA gene sequence analysis, this organism was closely related to Methanococcus jannaschii strain JAL-1T. However, despite the high percentage of similarity between their 16S rDNA sequences (97.1%), the DNA-DNA hybridization levels between these strains were less than 5%. On the basis of these observations and physiological traits, it is proposed that this organism should be placed in a new species, Methanococcus vulcanius. The type strain is M7T (= DSM 12094T). During the course of this study, the 16S rDNA sequence analysis placed Methanococcus sp. strain AG86T (= DSM 4213T) as a close relative of M. jannaschii strain JAL-1T. However, the weak level of DNA-DNA hybridization with this strain (< 10%) allowed the proposal that strain AG86T also constitutes a new species, Methanococcus fervens.

Base Composition↗
PubMed1999

Role of vascular endothelial-cadherin in vascular morphogenesis.

Vascular endothelial (VE)-cadherin is an adhesive transmembrane protein specifically expressed at interendothelial junctions. Its extracellular domain exhibits Ca2+-dependent homophilic reactivity, promoting cell-cell recognition. Mice deficient in VE-cadherin die at mid-gestation resulting from severe vascular defects. At the early phases of vascular development (E8.5) of VE-cadherin-deficient embryos, in situ differentiation of endothelial cells was delayed although their differentiation program appeared normal. Vascularization was defective in the anterior part of the embryo, while dorsal aortae and vitelline and umbilical arteries formed normally in the caudal part. At E9.25, organization of endothelial cells into large vessels was incomplete and angiogenesis was impaired in mutant embryos. Defects were more severe in extraembryonic vasculature. Blood islands of the yolk sac and clusters of angioblasts in allantois failed to establish a capillary plexus and remained isolated. This was not due to defective cell-cell recognition as endothelial cells formed intercellular junctions, as shown by electron microscopy. These data indicate that VE-cadherin is dispensable for endothelial homophilic adhesion but is required for vascular morphogenesis.

Animals↗
PubMed1998

Methanococcus infernus sp. nov., a novel hyperthermophilic lithotrophic methanogen isolated from a deep-sea hydrothermal vent.

An autotrophic, extremely thermophilic methanogen (ME(T)) was isolated from a deep-sea hydrothermal chimney sample collected on the Mid-Atlantic Ridge at a depth of 3000 m. The heavily flagellated cells are motile and coccoid shaped. The new strain growths between 55 and 91 degrees C, with an optimum growth temperature at 85 degree C. The optimum pH for growth is 6.5, and the optimum sea salt concentration for growth is around 25 g l-1. The organism uses H2 and CO2 as the only substrate for growth and methane production. Tungsten, selenium and yeast extract stimulate growth significantly. In the presence of CO2 and H2, the organism reduces elemental sulphur to hydrogen sulphide. The G+C content of the genomic DNA is 33 mol%. As determined by 16S gene sequence analysis, this organism is closely related to Methanococcus jannaschii strain JAL-1T. However, no significant homology was observed between them with DNA-DNA hybridization. It is proposed that this organism should be placed in a new species, Methanococcus infernus. The type strain is ME(T) (= DSM 11812T).

Anti-Bacterial Agents↗
PubMed1997

A 2.7-kb portion of the 5' flanking region of the murine glycoprotein alphaIIb gene is transcriptionally active in primitive hematopoietic progenitor cells.

The continuous generation of mature blood cells from primitive multipotent progenitor cells requires a highly complex series of cellular events that are still largely unknown. To examine the molecular events associated with the commitment of these hematopoietic progenitor cells to the megakaryocytic lineage, the alpha subunit of the platelet integrin alphaIIb beta3 was used as marker. Despite an abundance of information regarding the role of this integrin in platelet adhesion and aggregation, the mechanisms that control the expression of the genes that code for these proteins are poorly understood and the earliest hematopoietic cell capable of expressing them has not been clearly identified. Thus, a strategy was developed to eradicate, using a conditional toxigene, all the hematopoietic cells capable of expressing the alphaIIb gene in mice. This was achieved by targeting the expression of the gene encoding the herpes simplex virus thymidine kinase (tk), specifically to these cell types, using a 2.7-kb fragment of the 5'-flanking region of the murine alphaIIb gene. Three transgenic lines having 1, 3, and 4 copies of the transgene, respectively were produced and analyzed. Administration of ganciclovir (GCV) to these mice induced a severe thrombocytopenia, which was due to the depletion of the entire megakaryocytic lineage, as shown by bone marrow (BM) culture and electron microscopy analysis. The time required to attain a severe thrombocytopenia was dependent on the level of the expression of the transgene and varied from 7 to 11 days. This condition was completely reversed when GCV treatment was discontinued. Progenitor cell assays showed that the alphaIIb promoter was active in primitive hematopoietic progenitor cells possessing myeloid, erythroid, and megakaryocytic potential and that the transcriptional activity of the promoter decreased progressively as differentiation proceeded towards the erythroid and myeloid lineages.

Animals↗
PubMed1997

The isolated perfused porcine liver: assessment of viability during and after six hours of perfusion.

Isolated liver perfusion was developed for the study of liver physiology and preservation. The recent development of new perfusion devices and appropriate liver preservation solutions prompted us to reconsider liver perfusion for the specific purpose of evaluating viability in terms of biochemical changes, paying special attention to modifications in the histological ultrastructure. Twenty-two isolated pig livers were perfused with autologous blood. Arterio-portal perfusions were carried out using an extracorporeal perfusion circuit with a hollow fibre membrane oxygenator. Four groups of pig livers were studied using three different liver flushing solutions [Ringer's lactate, ELOHES, and University of Wisconsin (UW)] and two different oxygenation modalities. Liver function tests and histological studies were done. Our results revealed that a high partial oxygen pressure (PO2) level was deleterious to the ultrastructural elements of hepatocytes, in particular to the mitochondria. It was also associated with deficient metabolic performance, i.e., poor bile production and lack of aerobic metabolism. Normal blood gas values could be obtained with the use of air for liver oxygenation. Flushing of the liver with Ringer's lactate or a macromolecular solution such as ELOHES was associated with severe liver cell injuries, as reflected by a marked rise in liver enzymes and histological lesions. Satisfactory results were obtained when UW solution was used for liver harvesting. We conclude that an appropriate liver preservation solution, normal blood gas values, and normal physiological arterio-portal pressure and blood flow are essential for appropriate liver function with preservation of liver architecture and of hepatocyte ultrastructures. Total bilirubin in bile and Factor V are sensitive indicators of good liver function.

Animals↗