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Biomedical subjects

F Dumas

Publications and source records attributed to F Dumas.

At least 37 records · Page 2Linked to original sources
PubMed1999

Molecular expression of PSMA mRNA and protein in primary renal tumors.

Human prostate-specific membrane antigen (PSMA), a 100-kDa integral transmembrane glycoprotein, is considered to be a highly specific marker of the prostate gland, and has successfully been used as a marker of circulating prostatic epithelial cells. Extended PSMA homology has been demonstrated with a cDNA found in rat cerebral and renal tissues. In this study, we aimed to evaluate the expression of PSMA mRNA in a variety of human renal cancer tissues (n = 20) and cell lines (n = 12). Using reverse transcriptase-polymerase chain reaction, DNA sequencing, blottings, and specific anti-PSMA labelling with CYT 351 antibody, we identified PSMA mRNA and protein in normal and in neoplastic renal tissue. The sequence of the polymerase-chain-reaction products is identical to that of PSMA cDNA derived from prostate tissue. Immunological staining with the CYT 351 reveals that PSMA is expressed mainly in tubular cells. Since PSMA does not appear to be restricted to prostatic tissue, this novel biomarker may prove useful in the staging of renal cancer and in the search for the hematogenous spread of renal cells.

Adenocarcinoma↗
PubMed1999

Social presence effects in the Stroop task: further evidence for an attentional view of social facilitation.

In contrast with R. B. Zajonc's (1965) classic view about social facilitation-inhibition (SFI) effects, it was found that the presence of relatively unpredictable audiences and forced social comparison with a slightly superior coactor both facilitated performance in the Stroop task while inhibiting automatic verbal processing. Not only do these findings reveal that social presence can help inhibit the emission of dominant responses, providing further support for an attentional view of SFI effects, but they also demonstrate the power of social situations over what has been thought to be invariant automatic processing. As such, they are inconsistent with the view reiterated in more than 500 articles on Stroop interference over the past 60 years and suggest that more attention should be paid to the situations in which cognition takes place.

Adult↗
PubMed1998

[Rapid progress of cirrhosis in hepatitis C: the role of age at the time of viral contamination].

OBJECTIVE: The aim of this study was to assess predictive factors for the progression to liver cirrhosis in hepatitis C. METHODS: One hundred thirty six patients (79 men; 57 women; mean age 39 years) with transfusion or intravenous drug use-associated hepatitis C virus (HCV) infection were studied. Sex, cause of infection, duration of contamination, and genotype were studied as predictive factors of progression to liver cirrhosis. RESULTS: One hundred twenty three patients presented with chronic hepatitis without cirrhosis and 13 had cirrhosis. At the time of liver biopsy, rates of cirrhosis were: 0% before 40 years, 10% between 40 and 60 years, and 47% after 60 years. (p < 0.05). Rates of cirrhosis according to the age at the time of contamination were as follows: 3% before 30 years; 16% between 30 and 50 years; 46% after 50 years even though duration of the disease was comparable in the three groups. In multivariate analysis, two independent factors were associated with liver cirrhosis: age at contamination and duration of infection. CONCLUSION: Duration of infection and especially age at contamination seem better correlated with the probability of cirrhosis than the route of transmission or the genotype 1b. The results of this study suggest that progression to cirrhosis is slower in cases of contamination before 30 years of age than later on. Age at the time of contamination is an important predictive factor of progression to cirrhosis.

Adolescent↗
PubMed1998

Enteral ornithine alpha-ketoglutarate enhances intestinal adaptation to massive resection in rats.

Ornithine alpha-ketoglutarate (OKG) has been advocated in the treatment of critically ill patients for its anabolic effect on protein metabolism. Since OKG is a precursor of glutamine, arginine, and polyamines, key substrates of intestinal metabolism and function, we investigated the influence of OKG on intestinal adaptation and trophicity and on glutamine status after small bowel resection. After massive (80%) small bowel resection, rats were enterally fed for 7 days with a standard diet supplemented with either OKG (2 g/kg/d) or an isonitrogenous amount of glycine. OKG induced an adaptative hyperplasia of the villi, demonstrated in the jejunum by an increase in the villus height to crypt depth ratio (OKG v control, 4.3+/-0.4 v 3.3+/-0.5, P < .01) along with an increase (P < .05) in ornithine decarboxylase (ODC) activity (+80%) and ornithine content (+102%). Plasma glutamine (+25%) and muscle glutamine (anterior tibialis [AT], +43%; extensor digitorum longus [EDL], +54%) and protein (AT, +32%) were significantly higher (P < .05) after OKG administration, supporting its role in the restoration of glutamine pools. In summary, enterally administered OKG, which enhances intestinal adaptation after massive resection and improves muscle glutamine and protein content, could contribute significantly to nutritional management after small bowel resection.

Adaptation, Physiological↗
PubMed1998

Evaluation of reflex- and nonreflex-induced muscle resistance to stretch in adults with spinal cord injury using hand-held and isokinetic dynamometry.

BACKGROUND AND PURPOSE: In this study, we compared the intertrial reliability of resistive torque measurements obtained with hand-held and isokinetic dynamometers and examined the validity of the hand-held dynamometers for the assessment of spastic hypertonia, defined as reflex- and nonreflex-induced resistance to stretch. SUBJECTS: Nine subjects (mean age = 40.6 years) with a chronic (1-5 years) spinal cord injury participated. METHODS: The plantar flexors were stretched at 5 degrees /s (low velocity [LV]) and 180 degrees /s (high velocity [HV]) with an isokinetic dynamometer while the evaluator attempted to match these velocities with a hand-held dynamometer. Electromyographic activity of the soleus and tibialis anterior muscles as well as ankle displacements were recorded. Resistive torque and velocity, measured at -5 degrees of dorsiflexion, were averaged (n = 4). RESULTS: High intraclass correlation coefficients (ICCs) were found at LV and HV for both the hand-held (ICC = .93 and .84) and isokinetic (ICC = .99 and .93) dynamometers. With the hand-held dynamometer, lower resistive torques were found at LV (0.8 N.m) and HV (1.2 N.m), whereas higher velocities were attained at HV. CONCLUSION AND DISCUSSION: The results indicate that the reproducibility of resistive torques obtained with hand-held dynamometry compares with that obtained with isokinetic dynamometry and allows testing of velocities that can be adjusted to the specific level of resistance to stretch. Electromyography confirmed the validity of hand-held dynamometry for assessing reflex and nonreflex components of SH. [Lamontagne A, Malouin F, Richards CL, Dumas F. Evaluation of reflex- and nonreflex-induced muscle resistance to stretch in adults with spinal cord injury using hand-held and isokinetic dynamometry.

Adult↗
PubMed1998

De novo expression of CD44 in prostate carcinoma is correlated with systemic dissemination of prostate cancer.

AIMS: To evaluate the role of CD44 in early steps in the development of prostate cancer, and to assess the biological significance of preneoplastic lesions in prostate cancer. METHODS: 38 patients with clinically localised prostate cancer were studied. The standard form of CD44 (CD44H) and v6 isoform expressions were semiquantitatively evaluated on paraffin embedded tumour tissue by immunohistochemistry. Disseminated prostatic cells were detected by prostate specific membrane antigen reverse transcriptase polymerase chain reaction in the blood of each patient before radical prostatectomy. RESULTS: In normal or benign prostate glands, only basal cells showed CD44H and v6 labelling. Fourteen of the 38 prostate cancers (37%) had CD44H membranous staining of prostatic tumour cells. In 18 patients (47%), circulating prostatic cells were detected in blood before surgery. Although no correlation between the expression of CD44 and the Gleason score or staging was observed, a significant correlation was found between the expression of CD44H by tumour cells and prostatic cell blood dissemination (p = 0.04). In 28 cases, foci of prostatic intraepithelial neoplasia were observed, and nine had CD44H immunostaining. CONCLUSIONS: De novo expression of CD44 by prostatic tumour cells is associated with systemic dissemination of prostate cells independently of pathological criteria.

Adult↗
PubMed1998

[Evaluation and interest in new molecular markers in colon cancer].

The presence of colonic tumor cells in the circulation may predict colorectal carcinoma recurrence and metastases. We have developed a highly sensitive nested RT-PCR assay, with primers derived from the cytokeratin 20 (CK20) and the carcinoembryonic gene CGM2, to detect occult microdisseminated enterocytes in blood of colorectal cancer patients. Among 82 healthy controls analyzed, 40.2% (33/82) have a positive expression of CK20 mRNA which is not statistically different from the 45.5% (15/33) of positive results found in colon cancer patients. This sensitive method may detect non-tissue specific constitutive low level (illegitimate) expression of CK20 mRNA in peripheral nucleated blood cells (PNBC) of a significant number of healthy control as well as in a number of normal bone marrow. The low specificity of this assay therefore hampers its value to detect blood colon cancer dissemination. In 47 patients with colorectal carcinoma, CGM2 primers detected circulating enterocytes in 25 of them (53%). In disseminated Dukes' stage C disease patients, 17 out of 29 (59%) were found positive whereas in localized adenocarcinoma (Dukes's stage A and B), CGM2 primers detected enterocytes in 44% suggesting that an hematogenous spillage of colonic cells may be a relatively early event in colon cancer. None of the patients suffering from benign colonic pathologies or from diverticulitis were found positive for this assay. The analysis of 56 healthy individuals without known colorectal cancer, of 20 non-colorectal cancer patients and of 6 normal bone marrows provide evidence that this assay is highly specific and may predict an hematogenous spread of colonic cells in patients with organ-confined disease. Nevertheless, the clinical significance of enterocyte detection and the potential applications of this molecular tool merit longer term follow-up.

Biomarkers↗
PubMed1997

Sedimentation field-flow fractionation of cellular species.

More than 15 years ago a pioneering report on the separation of cellular material using sedimentation field-flow fractionation (SdFFF) was published. Surprisingly, only a few reports on SdFFF applications to cell separations are available as yet. The major limitations which seemed to slow the development of SdFFF applications in biology appeared to be related to the development of specific instrumentation. Therefore, guidelines are given for setting up a biocompatible SdFFF apparatus. SdFFF elution of cells with different characteristics was performed to demonstrate the efficiency, completeness, and rapidity of cell separations by this method. Retention data describing the effect of lifting forces on nucleated cells are compared to those for red blood cells (RBC). The effects of flow rates, field intensity, and injection protocol were studied using normal human RBC eluted in isotonic medium as a probe for retention conditions. When possible, data were also compared to previously published reports. Guidelines for elution and separation optimization are given. Using mixtures of nucleated and living red blood cells, viability studies showed a surprisingly high recovery of each type of material.

Cell Fractionation↗
PubMed1997

Molecular sorting of lipids by bacteriorhodopsin in dilauroylphosphatidylcholine/distearoylphosphatidylcholine lipid bilayers.

A combined experimental and theoretical study is performed on binary dilauroylphosphatidylcholine/distearoylphosphatidylcholine (DLPC/DSPC) lipid bilayer membranes incorporating bacteriorhodopsin (BR). The system is designed to investigate the possibility that BR, via a hydrophobic matching principle related to the difference in lipid bilayer hydrophobic thickness and protein hydrophobic length, can perform molecular sorting of the lipids at the lipid-protein interface, leading to lipid specificity/selectivity that is controlled solely by physical factors. The study takes advantage of the strongly nonideal mixing behavior of the DLPC/DSPC mixture and the fact that the average lipid acyl-chain length is strongly dependent on temperature, particularly in the main phase transition region. The experiments are based on fluorescence energy transfer techniques using specifically designed lipid analogs that can probe the lipid-protein interface. The theoretical calculations exploit a microscopic molecular interaction model that embodies the hydrophobic matching as a key parameter. At low temperatures, in the gel-gel coexistence region, experimental and theoretical data consistently indicate that BR is associated with the short-chain lipid DLPC. At moderate temperatures, in the fluid-gel coexistence region, BR remains in the fluid phase, which is mainly composed of short-chain lipid DLPC, but is enriched at the interface between the fluid and gel domains. At high temperatures, in the fluid phase, BR stays in the mixed lipid phase, and the theoretical data suggest a preference of the protein for the long-chain DSPC molecules at the expense of the short-chain DLPC molecules. The combined results of the experiments and the calculations provide evidence that a molecular sorting principle is active because of hydrophobic matching and that BR exhibits physical lipid selectivity. The results are discussed in the general context of membrane organization and compartmentalization and in terms of nanometer-scale lipid-domain formation.

Bacteriorhodopsins↗
PubMed1997

Audit of percutaneous endoscopic gastrostomy in long-term enteral feeding in a nursing home.

OBJECTIVES: Percutaneous endoscopic gastrostomy (PEG) is now easily used in the event of long-term enteral nutrition. Tolerance of long-term enteral feeding has been documented in different populations but the documentation is incomplete in the case of older and frail people. Our aim was to describe early and late tolerance in this population, and to propose ways in which it could be improved. DESIGN: Retrospective study in two parts: tolerance and quality of care; case-control study for tolerance. SETTING: A nursing home with 240 beds in south-west France. who had undergone PEG insertion between January 1990 and June 1994. Fifty-eight patients were involved, 12 under 65 years (48 +/- 10.6), and 46 over 65 (80.7 +/- 9.3). The gastrostomy insertion was performed because of a vegetative state in 6 patients, swallowing difficulties in 31 and anorexia in 21. A control group was gathered in December 1996, which included all patients for whom the question of nutritional support was mentioned books but where no artificial nutrition had been implemented due to the patients' or families' refusal or to a staff decision. This group included 50 patients, 5 younger than 65 years (54 +/- 8.3), and 45 older (84.7 +/- 7.6). In 22 cases the nutritional problem was swallowing difficulties and in 28 cases anorexia. Pressure ulcers were present before insertion in 34 patients in the PEG group and in 7 of the control group (p < 0.001). MAIN OUTCOME MEASURES: Prognosis, early and late cutaneous digestive (ileus, vomiting, gastroesophageal reflux) and pulmonary (bronchorrhea, dyspnea and aspiration pneumonia) complications for PEG and control groups, and patients with signs of poor behavioural tolerance of PEG were recorded in the chart. Audit of quality of care was performed in the PEG group using eight criteria: two concerned the pre-insertion period, two the early follow-up and four the long-term follow-up. RESULTS: Early mortality (4 weeks) was 13.8% in PEG (vs 10%, NS), mid-term mortality (between 4 and 8 weeks) was 12.1% (vs 14%, NS) and late mortality was 19.0% (vs 42.0%, length of follow-up 63.4 +/- 42.1 weeks compared to 53.1 +/- 63.8 weeks, NS). The duration of follow-up of the living patients was 71.6 +/- 61.8 weeks in PEG compared to 48.0 +/- 70.5 in the control group. Only 20% in PEG were free of any cutaneous complication around the insertion site, and 8 abscesses occurred during the first week. Pulmonary complications occurred in 39% of the PEG group (vs 30.0, NS). Aspiration pneumonia was significantly associated with swallowing difficulties in both groups (p < 0.05). Vomiting occurred for 15.5% of the PEG group (vs 12%, NS), ileus in 13.8% (vs 6%, NS). Gastroesophageal reflux was found in 2 PEG patients, compared to 1 case among the control patients. Pressures sores were healing in 20 out of 34 patients in the PEG group (vs 2 out of 7) and new ulcers appeared in 6 out of 24 (vs 8 out of 43). Fifteen (25.8%) of the PEG patients attempted to withdraw the tube.

Aged↗
PubMed1996

Production of the R2 subunit of ribonucleotide reductase from herpes simplex virus with prokaryotic and eukaryotic expression systems: higher activity of R2 produced by eukaryotic cells related to higher iron-binding capacity.

The R2 subunit of ribonucleotide reductase from herpes simplex virus type 2 was overproduced with prokaryotic and eukaryotic expression systems. The recombinant R2 purified by a two-step procedure exhibited a 3-fold higher activity when produced in eukaryotic cells. Precise quantification of the R2 concentration at each step of the purification indicated that the activity was not altered during the purification procedure. Moreover, we have observed that the level of R2 expression, in eukaryotic cells as well as in prokaryotic cells, did not influence R2 activity. Extensive characterization of the recombinant R2 purified from eukaryotic and prokaryotic expression systems has shown that both types of pure R2 preparations were similar in their 76 kDa dimer contents (more than 95%) and in their ability to bind the R1 subunit. However, we have found that the higher activity of R2 produced in eukaryotic cells is more probably related to a higher capability of binding the iron cofactor as well as a 3-fold greater ability to generate the tyrosyl free radical.

Animals↗