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Biomedical subjects

M Forêt

Publications and source records attributed to M Forêt.

At least 19 recordsLinked to original sources
PubMed2004

[Surveillance of infections in chronic hemodialysis patients].

OBJECTIVE: To confirm rates of infections from a previous survey in chronic hemodialysis patients; to get information about incidents and manipulations of vascular access-site, number and reasons of hospitalisation; to asses a relationship between the frequency of vascular access-site infections (VASI) and quality of care during the procedures of vascular access-site use. DESIGN: Prospective, multicenter survey performed from February 2000 to January 2001, including all patients underwent chronic hemodialysis in 5 participating centers. Standardized definitions used and different clinical and biological risk factors recorded. RESULTS: 429 patients for a total of 4273 dialysis months (DM) were enrolled. 245 infections in 164 infected patients were reported. The overall rate was 5.73 infections per 100 DM (18 VASI, 25 bacteraemia, 84 respiratory, 29 urinary tract, 1 endocarditis and 88 other infections). 50% of infections were microbiologically documented. 19 of 21 antibiotics resistant microorganisms were meticillin resistant Staphylococcus aureus. Compared to the incidence rate of fistula (0.05 per 1000 days of follow-up) or prosthesis related VASI (0.11), the incidence rate of catheter related VASI (0.65) was significantly higher. Poor hygiene and duration of catheter use were the significant risk factors for VASI showed by logistic analysis regression. VASI and bacteraemia occurred more frequently after incident or manipulation of the vascular access-site. The decrease of VASI between the 2 periods of survey was significantly higher in centers having reduced the catheter use and implemented written protocols. CONCLUSIONS: This second period of surveillance has confirmed the frequency of infections rate in chronic hemodialysis patients and particularly bacteraemia and VASI. This study has allowed to establish risk factors for infections and showed that VASI in hemodialysis are related to factors in part preventable.

Aged↗
PubMed1998

[Dialysis in octagenarians: search for mortality risk factors. Consecutive series of 30 patients].

OBJECTIVE: To assess renal replacement therapy in elderly subjects aged 80 years or more in order to depict factors predicting mortality. PATIENTS AND METHODS: We retrospectively studied 30 consecutive patients at the time of starting dialysis from January 1995 to August 1995 and followed this population though March 1996. RESULTS: Only past ischemic heart disease and emergency situations were emphasized as predictor factors of mortality risk. No difference according to mortality between hemodialysis and peritoneal dialysis subgroups was found. CONCLUSION: Excepting usual contraindications for uremic populations, no objective medical criteria are at present time sufficient for excluding chronic renal replacement therapy in very old patients. However, its effect on quality of life must be estimated in order to determine the cost/benefit ratio.

Age Factors↗
PubMed1997

[Mesenteric ischemia in hemodialyzed patients].

OBJECTIVES: Mesenteric ischemia is uncommon in the general population but is frequently encountered in chronic hemodialysis patients. We present here four cases which occurred in our unit within one year while only six cases had been observed in the preceding twenty years. OBSERVATIONS: Four chronic hemodialysis patients (age: 57 to 76 years) with renal failure due to diffuse atheromatous disease, presented non-occlusive mesenteric ischemia. One patient died and one underwent resection of the colon. For the final two patients, prophylactic therapy was initiated. DISCUSSION: Mesenteric ischemia is a severe condition which appears to occur more frequently in end-stage renal disease. In the chronic hemodialysis patient excessive ultrafiltration or a too rapid filtration rate can favor ischemia. Prophylactic measures must be taken at the first sign of ischemia, especially since clinical and biological features of mesenteric ischemia remain largely non-specific.

Aged↗
PubMed1996

[Twenty one years of hemodialysis in a patient with primary hyperoxaluria].

We report a male patient with primary hyperoxaluria from childhood who survived more than 21 years on conventional haemodialysis. Despite the severity of his bone disease, he was married and actively employed up until 2 years before his death. His condition really worsened a few months before his death. He presented with only renal and bone involvement and had hardly any cardiovascular complications, that was probably a reason for his prolonged survival. Such an evolution is very unusual and we speculate that the length of haemodialysis sessions in addition to the large surface of the membrane probably contributed to such an outcome. During the time period on HD, anemia was transiently controlled by recombinant erythropoietin despite oxalate involvement of the marrow. He was refused a liver-kidney transplant and died from malnourishment at 43 years of age. To our knowledge, such an outcome has not yet been reported. It shows that careful prolonged hemodialysis sessions should be helped in admet patients without severe cardiovascular involvement.

Adult↗
PubMed1996

[Ophthalmologic manifestations of dialysis. Retrospective study on 81 patients].

In this work, we looked at the results of a retrospective study carried out in our unit on the ocular manifestations in the dialysed chronic renal failure patient. Eighty-one of our 189 patients had an ophtalmic examination. Thirty-six showed a retinopathy, 26 suffered from a corneoconjunctival alterations, 19 from a cataract, 6 a vascular thrombosis, 4 a glaucoma and one motor-ocular paralysis. There was no significant difference for age and sex between the 81 patients and the group of 108 who did not have an ophtalmic examination. But this difference was positive for duration of time on dialysis (p = 0.01). There is a correlation between the presence of a cataract and the age of the patients (p = 0.01). There was no link between the different types of ophtalmic problems on the one hand, and the age, sex, time on dialysis, type of dialysis, original nephropathy, hypertensive history or anterior renal transplantation on the other hand.

Cataract↗
PubMed1995

[What are the prerequisites for establishing a peritoneal dialysis treatment? (Training center, the place of private practice nurses, the administrative structure of management)].

In spite of the same quality of results in term of five year survival by peritoneal dialysis (PD) compared to hemodialysis (HD), this method of renal substitutive therapy is concerning no more than 7% ESRF patients in France. What structural inadaptations could account for such striking differences between the two modalities? We present here the results of a French multi-center survey and our proposal for improving the actual tendency. Nonante PD centers were included representing a total number of 1592 patients, among them 90% were on continuous ambulatory peritoneal dialysis. We could observe a predominant proportion of public district services and non-profit associations. Sixty per cent of PD units were part of hemodialysis centers and 20% were totally independent. Patient mean age was very old, with limited autonomy, necessitating frequent visits of liberal nurses for 57% patients. We suggest to reinforce the role of non-profit making associations and to reorganize the existing centers on two levels in term of facilities, personal services and on functional modalities according to the number of treated patients.

France↗
PubMed1993

Effects of a heterogeneous set of xenobiotics on growth and plasma membranes of mammalian and fungal cell cultures.

A comparison of the toxicity of 45 selected, heterogenous substances on two test organisms of different taxonomic levels, the yeast Saccharomyces cerevisiae and Chinese hamster ovary (CHO) cells, was made. In addition, effects on the yeast plasma membrane-integrated H(+)-ATPase and on the CHO adenosine uptake system were investigated. For all test systems, log EC50 values highly correlated with log EC20 values. Good correlations were obtained between CHO proliferation rate and yeast growth rate (r = 0.80). However, CHO cells were about four times more sensitive than yeast. A good accordance was also found between effects on yeast cell growth and on the H(+)-ATPase, indicating a plasma membrane impairment as a major cause of cytotoxicity. These findings were supported by correlations of log EC20 values with the log Pow as a measure for lipophilicity. Although the test systems demonstrated different dependencies, the main trend reflected an increasing toxicity with increasing lipophilicity. Comparisons with data from in vivo test systems suggest that these in vitro test systems could be implemented for initial estimation of basic toxicity and the detection of outliers thereby reducing the number of tests with higher animals.

Adenosine↗
PubMed1991

Interaction of xenobiotics on the glucose-transport system and the Na+/K(+)-ATPase of human skin fibroblasts.

The effects of individual and combined xenobiotics on functional properties of the plasma membrane of human skin fibroblasts were investigated. Good correlations between toxic effects on the D-glucose transport system or the Na+/K(+)-ATPase and the lipophilicity of the substances could be observed. The linear regression coefficients plotting log EC20 values (doses, leading to 20% inhibition) versus log Pow (octanol/water partition coefficient) were r = 0.95 (P less than 0.05). The combination of lipophilic with less lipophilic xenobiotics, such as pentachlorophenol with 4-chloroaniline, leads to additional effects. However, when the detergent sodium dodecyl benzenesulfonate was combined with the herbicide 2,4-dichlorophenoxyacetate (2,4-D), the toxic effect of 2,4-D on the Na+/K(+)-ATPase decreased considerably. The results support in general the assumption that the inhibition of integral functional proteins is based on an accumulation of xenobiotics in the plasma membrane, probably due to the enhanced membrane fluidity. Thus, the basic toxicity of xenobiotics can be predicted by their physicochemical properties.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1991

Interaction with functional membrane proteins--a common mechanism of toxicity for lipophilic environmental chemicals?

1. The effects of several phenols, anilines and aliphatic alcohols on yeast plasma membrane H(+)-ATPase and purine transport system as well as on Na+, K(+)-ATPase and adenosine uptake by Chinese hamster ovary cells (CHO) were investigated. 2. In all cases an inhibition was observed, which could be correlated with the octanol/water partition coefficients of the substances tested, thus making quantitative structure-activity predictions possible. 3. The observed effects correlated well with the influence of the chemicals on cell growth. 4. The results suggest a common mechanism of toxicity by the action of hydrophobic xenobiotics on biomembranes.

Adenosine Triphosphatases↗
PubMed1987

Acute anaphylactoid reactions during hemodialysis in France.

A retrospective survey of anaphylactoid reactions during dialysis in France was conducted. In 52 of 112 hemodialysis units surveyed 111 patients who had suffered one or more anaphylactoid reactions during dialysis were identified. According to the Hamilton/Adkinson classification, in 31 patients reactions were minor, in 54 patients moderate, and in 26 patients severe. Four patients died of their reactions. A preponderance of reactions (75 and 11%) occurred with cuprammonium cellulose hollow-fiber and plate dialyzers, respectively. Severe dialyzer reactions were found to occur more frequently after the long (weekend) interdialytic interval. In an in vitro study, six brands of cuprammonium cellulose hollow-fiber dialyzers were rinsed with water and the eluates analyzed by size exclusion chromatography for contaminant particles. Substantial variation in the amount of extractable material was found between dialyzers of different brands, despite the fact that all dialyzers used membranes from the same manufacturer. Previous data by others has suggested that this extractable material is a derivative of cellulose. Results of our epidemiologic survey in France are similar to those previously reported in the United States and suggest an increased incidence of dialyzer reactions with ethylene oxide-sterilized cuprammonium cellulose dialyzers. The presence of cellulose-derived particles in the rinsing fluid of such dialyzers and the possible increased incidence of reactions after the long (weekend) interdialytic interval suggest that allergy to cellulose-derived particles eluted from cellulosic dialyzers may contribute to dialyzer hypersensitivity reactions.

Anaphylaxis↗
PubMed1986

Evaluation and tolerance of a new polycarbonate membrane in elderly patients. Preliminary results.

We studied the performance and tolerance of a new capillary hemodialyzer using a polycarbonate membrane (Gambrane PCD 1000) in a group of 5 elderly patients (mean age 68 years). The ultrafiltration coefficient is 6 (justifying the monitoring control of weight loss) and clearances for small molecules are comparable with cellulosic membranes. A good tolerance during 300 sessions was observed; nevertheless, an important neutropenia was noted in 2 out of 5 patients. The complement activation measured by the dosage of the C3a Desarg fraction existed in all the patients, reaching an average 6 times the initial level compared to 40 times for Cuprophan. Complement activation and neutropenia are considerably reduced by the reuse of the hemodialyzer as it was described for the cellulosic membranes.

Age Factors↗
PubMed1985

Mechanisms of hypersensitivity reactions during hemodialysis.

We suggest that many severe hypersensitivity reactions during dialysis are IgE mediated (classical anaphylaxis). Besides ETO there must be other substances involved which are not extractable from the dialyzer (e.g. heparin). Some severe reactions are not explained by high IgE levels in the serum. However, in vitro complement activation gives no indication of an anaphylatoxin mediated reaction mechanism, at least in the severe cases of hypersensitivity.

Complement Activation↗
PubMed1983

Does 2H2O also protect membrane-bound enzymes?

Thermal inactivation studies performed with several membrane-bound enzymes such as chitin synthase, cytochrome c oxidase, nucleotidase, as well as bacterial, mitochondrial and plasma membrane ATPases from yeast in H2O and 2H2O indicated that most of these enzymes could not be protected by 2H2O against thermal inactivation. Only the Escherichia coli ATPase, which is located at the surface of the membrane, and the cytochrome c oxidase were stabilized by heavy water.

Adenosine Triphosphatases↗
PubMed1978

On the mechanism of substrate binding to the purine-transport system of Saccharomyces cerevisiae.

The yeast Saccharomyces cerevisiae takes up adenine, guanine, hypoxanthine, and cytosine via a common energy-dependent transport system. The apparent affinity of the transport system to these and other purines and pyrimidines is correlated with their capability to be protonated to the positively charged form. Further organic molecules are competitive inhibitors when they are cationic, e.g. guanidine and octylguanidine in contrast to urea, or hexadecyltrimethylammonium in contrast to dodecylsulfate and Triton X-100. The influence of the pH on the kinetic constants of hypoxanthine transport points to a stoichiometry of one proton being associated to the transport system together with one substrate molecule. The pKa values of two ionizable groups that are involved in substrate binding are revealed; one of which (pKa = 1.8) may be attributed to the substrate, the other (pKa = 5.1) to an amino acid residue in the recognition site of the transport system. Studies with group-specific inhibitors indicate that this amino acid residue contains a carboxyl group. The results are in accordance with the assumption that a carboxyl group of the transport system, a proton and a substrate molecule arrange to an uncharged ternary complex.

Biological Transport, Active↗