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B Gachot

Publications and source records attributed to B Gachot.

54 records · Page 3Linked to original sources
PubMed1994

Zinc transport and metallothionein induction in primary cultures of rabbit kidney proximal cells.

Primary cultures of isolated rabbit renal proximal cells were grown on collagen-coated permeable supports. The confluent epithelia were polarized, making possible the measurement of uptakes and effluxes across the apical and the basolateral membranes. Uptakes of 65Zn were assessed under initial rate conditions, after 0.5 min incubation. The kinetic parameters of apical uptake were a Jmax of 25.1 +/- 5.3 pmol min-1 (micrograms DNA)-1, a Km of 43.3 +/- 7.3 microM and an unsaturable constant of 0.105 +/- 0.029 (n = 7) at 37 degrees C. Cadmium competitively inhibited the zinc uptake, with a Ki value of 24.5 +/- 7.3 microM. Basolateral uptake was characterized by a high capacity (Jmax = 227.9 +/- 46.6 pmol min-1 (micrograms DNA)-1) and an affinity similar to that of the apical uptake (Km = 35.4 +/- 14.2 microM). Cadmium had no effect on the basolateral zinc uptake. Effluxes across the basolateral face of the epithelium always exceeded those across the apical face. Excess zinc in the culture medium induced the synthesis of metallothionein in the epithelia, as judged by the rate of [35S]cysteine incorporation into a fraction of cytosolic proteins. Metallothionein induction did not appear to modify the kinetic parameters of the apical zinc uptake. These data suggest that separate saturable transport systems are responsible for the apical and basolateral zinc uptakes in proximal renal cells. Induction of metallothionein had no apparent effect on apical zinc uptake in this system.

Animals↗
PubMed1993

Septic shock due to toxoplasmosis in patients infected with the human immunodeficiency virus.

PURPOSE: To describe the presentation and clinical course of septic shock due to Toxoplasma gondii in patients infected with the human immunodeficiency virus (HIV). PATIENTS AND METHODS: From April 1988 to February 1992, nine HIV-infected patients were admitted because of predominant septic shock (7 patients) or developed septic shock in the ICU (2 patients). The recent CD4+ cell count ranged from 2 to 84 x 10(6)/L. RESULTS: The main clinical features were (1) a history of fever for longer than 15 days, with a recent increase to more than 39.5 degrees C; (2) a recent history of dyspnea (< 15 days, 8 cases; < 7 days, 3 cases); and (3) recent onset of thrombocytopenia (6 of 9 cases). All patients were in shock (hyperkinetic profile in 6 of 7; hypokinetic in 1 of 7), and 8 of 9 were in respiratory distress (ratio of PaO2 over fractional concentration of oxygen in the inspired gas of 117 +/- 23; range, 88 to 155). Chest roentgenograms revealed diffuse alveolar infiltrates in six of nine cases. The serum lactate dehydrogenase (LDH) activity was 6,510 +/- 5,080 IU/L (range, 1,010 to 15,450 IU/L). Serologic tests for T gondii were negative in two cases. Toxoplasma gondii was isolated from lung (9/9), bone marrow (5/7), or blood (2/2). One, 3, and 2 patients had brain, ocular, and myocardial involvement, respectively. No other microbial pathogens were isolated. Seven patients died, 5 less than 3 days after admission. CONCLUSION: Disseminated toxoplasmosis can cause septic shock in HIV-infected patients. In two cases, the disease was probably a primary infection. The association of high fever, acute dyspnea, recent onset of thrombocytopenia, and a very high level of LDH activity is suggestive of disseminated toxoplasmosis.

AIDS-Related Opportunistic Infections↗
PubMed1992

Continuous positive airway pressure by face mask or mechanical ventilation in patients with human immunodeficiency virus infection and severe Pneumocystis carinii pneumonia.

We reviewed the records of 44 patients with AIDS who had 45 episodes of severe Pneumocystis carinii pneumonia (PCP). While 9 patients required intubation and mechanical ventilation (MV) on admission, continuous positive airway pressure (CPAP) by face mask was the initial measure in 36 episodes. There were 25 patients managed with CPAP alone, 23 of whom survived. Among the reasons for delayed intubation and MV (11 patients) was that treatment failure was strongly associated with non-survival, since all 6 such patients died. The in-hospital mortality for severe PCP in this study was 33% overall, and reached 65% for mechanically ventilated patients. The 1-year survival was 43% (95% confidence interval, 28%-58%). These data confirm the improved prognosis for patients with AIDS and severe PCP, and suggest that mask CPAP may be an adequate mean of ventilatory support in this setting.

Adult↗
PubMed1992

Effects of cadmium and copper on zinc transport kinetics by isolated renal proximal cells.

Zinc, cadmium, and copper are known to interact in many transport processes, but the mechanism of inhibition is widely debated, being either competitive or noncompetitive according to the experimental model employed. We investigated the mechanisms of inhibition of zinc transport by cadmium and copper using renal proximal cells isolated from rabbit kidney. Initial rates of 65Zn uptake were assessed after 0.5 min of incubation. The kinetics parameters of zinc uptake obtained at 20 degrees C were a Jmax of 208.0 +/- 8.4 pmol.min-1.(mg protein)-1, a Km of 15.0 +/- 1.5 microM and an unsaturable constant of 0.259 +/- 0.104 (n = 8). Cadmium at 15 microM competitively inhibited zinc uptake. In the presence of 50 microM cadmium, or copper at both 15 and 50 microM, there was evidence of noncompetitive inhibition. These data suggest that zinc and cadmium enter renal proximal cells via a common, saturable, carrier-mediated process. The mechanisms of the noncompetitive inhibition observed at higher concentrations of cadmium or with copper require further investigation, but may involve a toxic effect on the cytoskeleton.

Animals↗
PubMed1991

Zinc uptake by proximal cells isolated from rabbit kidney: effects of cysteine and histidine.

The aim of this study was to characterize the mechanisms of zinc transport in proximal cells isolated from rabbit kidney cortex. Uptakes of 65Zn were assessed under initial rate conditions, after 0.5 min of incubation. The kinetic parameters obtained at 20 degrees C were a Km of 15.0 +/- 1.5 microM, a Jmax of 208.0 +/- 8.4 pmol min-1 (mg protein)-1, and an unsaturable constant of 0.259 +/- 0.104 (n = 8). Cadmium competitively inhibited the zinc uptake, with a Ki value of 13.0 +/- 2.8 microM, while zinc competitively inhibited 109Cd uptake by isolated cells. Cysteine and histidine stimulated zinc transport at an amino acid:zinc molar ratio ranging from 1:1 to 8:1. This stimulation was not observed in the absence of a sodium gradient. At a molar ratio greater than 16:1 (i.e. 400 microM cysteine or histidine and 25 microM Zn), there was evidence of inhibition. These data suggest that zinc enters renal proximal cells (a) as a free ion via a saturable carrier-mediated process or an unsaturable pathway and (b) complexed with cysteine or histidine, by means of a sodium/amino acid cotransport mechanism.

Animals↗
PubMed1990

[HIV infection and "malignant" strongyloidiasis].

Disseminated Strongyloides stercoralis infection occurs in immunocompromised patients. Despite the epidemiological overlap of HIV infection and strongyloidiasis observed in certain parts of the world, only six cases of dissemination have been reported in AIDS patients. The clinical presentation has no special features, except for the frequency of other opportunistic infections. The prognosis is poor. This lack of association between disseminated strongyloidiasis and HIV infection had led to the exclusion of extra-intestinal forms of this paraistosis from the revised classification of AIDS.

HIV Infections↗
PubMed1990

Severe tuberculosis in patients with human immunodeficiency virus infection.

Tuberculosis has now been well documented as a complication of infection with human immunodeficiency virus (HIV), but no studies concern patients requiring admission to the ICU. We report 12 cases of severe disseminated tuberculosis in patients who were seropositive for HIV. Eight patients had diffuse pulmonary involvement responsible for acute respiratory failure, 7 of whom required mechanical ventilation. Four developed septic shock, and in 3 blood cultures were positive for M. tuberculosis. Four patients had central nervous system involvement, with coma requiring mechanical ventilation 3 times. Rapid diagnosis was permitted in 10 patients by acid-fast smears of pulmonary specimens (8 patients) and/or tissue biopsies (4 patients). Seven patients died despite intensive therapy; autopsy was performed in 4 patients, showing disseminated tuberculosis. On the basis of this report, tuberculosis in HIV infection may present as an overwhelming systemic disease and thus requires an aggressive diagnostic and therapeutic approach.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Electrical properties of rabbit early distal convoluted tubule in primary culture.

Distal bright convoluted tubules (DCTb) were microdissected from rabbit kidney cortex and cultured in a hormonally defined medium. The quality and the degree of polarization of the growing epithelia were assessed by indirect immunofluorescence studies using a monoclonal antibody raised against the apical membrane of the DCTb in situ. The cultured monolayers had a high hexokinase activity and a low gamma-glutamyl transferase activity compared with cultured proximal convoluted tubules. Adenosine 3',5'-cyclic monophosphate production was stimulated by calcitonin and insensitive to parathyroid hormone, vasopressin, and isoproterenol. Both 20- and 30-day-old cultures developed an apical-negative transepithelial potential of -3.1 and -22.3 mV, respectively. Amiloride reversibly reduced the voltage by 90% only when applied on the apical side of the monolayers. Phenamil (10(-8), 10(-6) M) had the same effect as amiloride. Calcitonin reversibly decreased the transepithelial voltage. These data support the hypothesis that, in the DCTb in primary culture, the transepithelial voltage is due to the presence of Na channels and that calcitonin modulates this transport pathway.

Amiloride↗
PubMed1988

Patch clamp study on primary culture of isolated proximal convoluted tubules.

Primary cultures were obtained from microdissected rabbit proximal tubules (S1 segments). The growing epithelia were maintained in culture for up to 30 days. Electron microscopy study revealed that the cells formed a monolayer and showed a morphological polarity with apical microvilli and tight junctions. An immunofluorescence technique using two monoclonal antibodies raised against two apical brush border enzymes of the proximal tubule (LAP, DPP IV) revealed that these enzymes were expressed in the cultured cells. Membrane associated and cytosolic enzyme activities were measured on 12, 20 and 30-day-old cultures. Cultured epithelia exhibited leucine aminopeptidase, gamma glutamyl transferase and fructose 1-6 biphosphatase activities that remained constant for up to 30 days, whereas alkaline phosphatase activity decreased in the oldest cultures. Hexokinase activity on the other hand, increased after 12 days of culture. Cyclic AMP synthesis was stimulated by parathyroid hormone at 12, 20 and 30 days of culture and was insensitive to arginine vasopressin. After 20 days of culture the epithelia grown on permeable supports developed a transepithelial potential of -0.13 mV (apical negative) and a transepithelial resistance of 37 omega cm2 that increased to -1.13 mV and 60 omega cm2 respectively in 30-day-old cultures. The patch clamp technique was applied to the apical membrane of 12-15-day-old cultures. In the whole cell recording configuration, a cellular potential of -61.5 mV was measured, which was mainly due to K+ diffusion. A non-selective cationic channel was present in the apical membrane of the cultured cells. In cell-attached patches the channel carried an inward current and had a conductance of 13 pS. On excised patches the channel discriminated poorly between Na+ and K+ and was impermeant to Cl- and its conductance ranged between 20 and 28 pS. The channel activity was not voltage dependent but required a high calcium concentration (1 mM Ca2+) on the cytoplasmic face.

Animals↗
PubMedDate not supplied

Possible prognostic significance of a brief rise in parasitaemia following quinine treatment of severe Plasmodium falciparum malaria.

An increase in parasitaemia is not uncommon after initiation of treatment for Plasmodium falciparum malaria, but its exact significance is unknown. The time-course of parasitaemia was assessed retrospectively in 33 patients with severe imported malaria. In 19 patients (group 1) mean parasitaemia (+/- SEM) fell promptly after starting quinine treatment, from 24.9 +/- 4.1% on day 0 to 9.7 +/- 2.3% on day 1 and 1.8 +/- 0.7% on day 2. In 14 other patients (group 2), parasitaemia did not change significantly or increased, with mean parasitaemia (+/- SEM) of 9.5 +/- 2.1% on day 0, 17.2 +/- 2.6% on day 1, and 3.7 +/- 1.8% on day 2. Simplified acute physiology scores on admission (mean +/- SEM) were 17.4 +/- 1.4 in group 1 and 11.7 +/- 1.0 in group 2 (P = 0.006). The mean number of complications of malaria per patient (+/- SEM) was 2.9 +/- 0.5 in group 1 and 1.6 +/- 0.3 in group 2 (P = 0.046). Two group 1 patients died. Initially, more than 95% of peripheral blood parasites were tiny and small rings in both groups, and this distribution was unchanged on day 1, suggesting that the parasitaemia increase in group 2 was not due to release of sequestered mature parasites. In severe falciparum malaria, a rise in parasitaemia after treatment initiation may be of favourable prognostic significance and should not lead to aggressive therapeutic approaches such as exchange transfusion.

Adult↗