PubMed Health⌕ Search

Biomedical subjects

P Douville

Publications and source records attributed to P Douville.

At least 19 recordsLinked to original sources
PubMed2001

Effects of electric and magnetic fields from high-power lines on female urinary excretion of 6-sulfatoxymelatonin.

In 1998, the authors studied the effect of residential exposure to electric and magnetic fields from high-power lines on female urinary excretion of 6-sulfatoxymelatonin (6-OHMS) in the Quebec city, Canada, metropolitan area. A sample of 221 women living near a 735-kV line was compared with 195 women the same age living away from any power lines. Participants provided morning urine samples on 2 consecutive days and wore a magnetic dosimeter for 36 consecutive hours to measure personal magnetic exposure. The indoor electric field was assessed by spot measurements. After adjustment for other factors associated with low melatonin secretion, such as medication use or light exposure, nighttime concentration of 6-OHMS was similar in the two groups. When either 24-hour or sleep-time exposure to magnetic field or electric field measurements was used, no exposure-effect relation was evident. However, the trend of decreasing 6-OHMS concentration with age was more pronounced for women living near the lines, as was a lower 6-OHMS concentration in women with high body mass index. Chronic residential exposure to magnetic fields from high-power lines may accentuate the decrease in melatonin secretion observed in some vulnerable subgroups of the population.

Adult↗
PubMed2001

Captopril suppression versus salt loading in confirming primary aldosteronism.

This prospective study was designed to compare the captopril suppression test with the salt-loading approach to confirm the diagnosis of primary aldosteronism. A total of 49 patients were referred with a presumed diagnosis of primary aldosteronism. The captopril test was performed in the morning with patients in the seated position after overnight fasting. Blood samples for plasma aldosterone were obtained before captopril administration (25 mg PO) and again 2 hours later. Patients were then subjected to a high salt diet (300 mmol sodium per day for 3 days). On the third day, urinary sodium (24 hours) was measured, and plasma aldosterone levels were measured at 8:00 AM (recumbent) and at noon (standing). Of the 49 patients, 44 had nonsuppressible aldosterone concentrations with all the clinical characteristics of primary aldosteronism: 22 patients had surgically confirmed unique adenoma, and 22 patients had presumed bilateral hyperplasia. There was a significant correlation between plasma aldosterone values of salt-loaded patients (mean of 8:00 AM and noon results) and the values 2 hours after captopril administration (r=0.8, P<0.01). Plasma aldosterone cumulative distribution curves in primary aldosteronism patients (adenoma and hyperplasia) were not significantly different between the 2 suppression tests. Our results showed that the captopril suppression test is as effective as sodium loading in confirming the diagnosis of primary aldosteronism.

Adult↗
PubMed2000

HDL cholesterol and TaqIB cholesteryl ester transfer protein gene polymorphism in renal transplant recipients.

Decreased serum levels of high-density lipoprotein cholesterol (HDL-C) are a well-known risk factor for coronary heart disease (CHD) in the general population and have been suggested as one of the best predictor of CHD after renal transplantation. However, very heterogeneous HDL-C levels have been reported in renal transplant recipients. In this patient population, serum HDL-C levels are determined by complex interactions between hormonal, environmental (such as a high amount of abdominal adipose tissue), and genetic factors and drugs (particularly glucocorticoids). We, therefore, evaluated the effects of the cholesteryl ester transfer protein (CETP) gene TaqIB polymorphism as well as of abdominal obesity on HDL-C levels in 78 male renal transplant recipients who were receiving azathioprine and/or ciclosporin A in combination with prednisone as immunosuppression. The patients were classified into genotypic groups according to the presence or absence of the restriction site (B1 allele or B2 allele, respectively). The distribution of CETP genotypes was similar to that previously described in the general population. Overall, HDL-C levels were 19 and 26% higher in B1B2 and B2B2 patients as compared with B1B1 homozygotes (p < 0.05), even after control for other lipid measurements. Patients with abdominal obesity (waist girth >/=93 cm) showed reduced HDL-C levels as compared with lean (waist girth <93 cm) patients (1.20 +/- 0.28 vs. 1.42 +/- 0.41 mmol/l, respectively, p < 0.01). Moreover, the HDL-C levels were markedly affected by the CETP TaqIB polymorphism in lean patients (+28 and +41% in B1B2 and B2B2 as compared with B1B1 patients, p < 0.05), but no significant difference was observed among obese patients. Significantly lower total cholesterol:HDL-C ratios were obtained in lean B2B2 homozygotes, suggesting that these patients could be less susceptible to atherosclerosis than lean B1B1 homozygotes. In addition, patients with the B1B1 genotype had more documented CHD as compared with patients carrying at least one B2 allele, supporting the protective effect of the B2 allele against CHD. In conclusion, considerable variation in HDL-C levels appears to be explained by the CETP TaqIB gene polymorphism in male renal transplant recipients, but this potential protective gene effect appears strongly reduced by concomitant abdominal obesity.

Abdomen↗
PubMed1998

Effect of terminal renal failure on the ratio of free to total prostate-specific antigen.

OBJECTIVES: To evaluate the effect of terminal renal failure on the ratio of free to total prostate-specific antigen (PSA). METHODS: We measured free and total PSA in a group of 48 men on chronic hemodialysis. Samples were taken before dialysis and compared with a control group of 101 men without known prostatic or renal disease. Measurements of total and free PSA were made simultaneously with an ES-300 analyzer from Boehringer Mannheim according to the manufacturer's instructions. RESULTS: Patients on hemodialysis have lower complexed PSA but higher free PSA than controls. Therefore, we observed a markedly higher calculated proportion of free PSA in the dialysis group (0.54 +/- 0.16 vs. 0.33 +/- 0.14, p < 0.00001). The calculated proportion of free PSA decreases progressively as the levels of total PSA increases from 0 to 4 microg/l in both groups. By multivariate analysis, total PSA (p < 0.00001) and dialysis (p < 0.00001) were independent predictors of the fraction of free PSA. Age had no significant effect after correction for total PSA (p = 0.23). CONCLUSION: Patients on hemodialysis have normal total PSA but a significantly higher proportion of free PSA. Caution is therefore recommended for the interpretation of free PSA in that population since cutoff established in patients without renal disease may be inappropriate.

Autoanalysis↗
PubMed1995

Transcription factors interacting with herpes simplex virus alpha gene promoters in sensory neurons.

Interference with VP16-mediated activation of herpes virus immediate-early (or alpha) genes is thought to be the major cause of establishing viral latency in sensory neurons. This could be brought about by lack of a key activating transcription factor(s) or active repression. In this study we find that sensory neurons express all important components for VP16-mediated alpha gene induction, such as the POU transcription factor Oct-1, host cell factor (HCF) and GABP alpha/beta. However, Oct-1 and GABP alpha/beta are only present at low levels and the VP16-induced complex (VIC) appears different. We do not find protein expression of the transcription factor Oct-2, implicated by others as an alpha gene repressor. The POU factor N-Oct3 (Brn 2 or POU3F2) is also present in sensory neurons and binds viral TAATGARAT motifs with higher affinity than Oct-1, indicating that it may be a candidate repressor for competitive binding to TAATGARAT motifs. When transfected into HeLa cells, where Oct-1 and GABP alpha/beta are highly abundant, N-Oct3 represses model promoters with multimerized TAATGARAT motifs, but fails to repress complete alpha gene promoters. Taken together our findings suggest that modulation of alpha gene promoters could contribute to viral latency when low concentrations of the activating transcription factors Oct-1 and GABP alpha/beta prevail. Our data, however, refute the notion that competing Oct factors are able to block alpha gene transcription to achieve viral latency.

Animals↗
PubMed1995

Positive and negative regulation at the herpes simplex virus ICP4 and ICP0 TAATGARAT motifs.

The control of the ICP0 and ICP4 immediate early genes of herpes simplex virus (HSV) can critically determine the course of viral lytic or latent infections. Their promoters contain so-called TAATGARAT motifs that are activated via a multiprotein complex which includes cellular proteins Oct-1 and HCF and the viral activator (VP16 (= Vmw65, alpha TIF). Relative to the ICP4 promoter TAATGAGAT sequence, the ICP0 promoter motif has a 5' extension that includes a full octamer sequence (ATGCTAATGATAT). It seemed possible that this overlapping octamer site might render the ICP0 promoter element more active by allowing tighter binding of the Oct-1/VP16 complex or more vulnerable to repression by other Oct proteins. Our experiments favor the former possibility. On the one hand, the extended ICP0 site shows stronger binding of the Oct-1/VP16 complex compared to the ICP4 site. Moreover, transcription of a reporter gene with multiple ICP0 sites is strongly activated by VP16 in transfected cells. On the other hand, the ICP0 site is largely refractory toward repression by a different Oct factor (N-Oct2 = Brn1) which competes with Oct-1/VP16 for the site. In marked contrast, multiple copies of the conventional TAATGAGAT motif of ICP4 are poorly activated by VP16, and transcription from this site can be completely repressed by N-Oct2. However, inclusion of the neighboring CGGAAR motifs from the ICP4 promoter, which bind factors GABP alpha and beta, results in a strong synergistic activation. This activity, like that of the complete ICP4 promoter, becomes refractory to repression by competing N-Oct2. Thus the standard TAATGARAT motif of ICP4 is by itself less active and more vulnerable to repression than the extended ICP0 motif, and its activation depends upon synergism with neighboring DNA sites and their cognate factors. This difference between the two types of TAATGARAT motifs may allow for a more complex transcriptional regulation by factor combinations.

Base Sequence↗
PubMed1994

A new rapid immunoinhibition pancreatic amylase assay: diagnostic value for pancreatitis.

A new rapid immunoinhibition pancreatic amylase assay was compared to total amylase and lipase in an unbiased sample of 1005 emergency department patients with suspicion of pancreatitis, of which 55 had a final diagnosis of pancreatitis. Imprecision of the assays for both amylases (less than 2.5%) were better than for lipase (less than 6.1%). Correlation (R2) of pancreatic amylase with total amylase was 0.991 but only 0.789 with lipase. Using Receiver Operator Characteristics analysis, the best diagnostic cutoff point for all three enzymes was near the upper limit of the reference interval. With pancreatic amylase, sensitivity, specificity, and predictive values for positive and negative results are, respectively, 85.5, 92.5, 39.8, and 99.1%; we found similar values for lipase but poorer values (78.2, 92.0, 36.1, and 98.7%) for total amylase. Tests combination did not improve the diagnostic performance significantly. In the diagnosis of pancreatitis, pancreatic amylase (p = 0.037) and lipase (p = 0.049) had better diagnostic performance than total amylase. The correct diagnosis of pancreatitis could be achieved in 47 instead of 43 patients with either pancreatic amylase or lipase as opposed to total amylase among 1005 patients in this study. We conclude that pancreatic amylase and lipase are incrementally better diagnostic tools than total amylase for the diagnosis of pancreatitis.

Acute Disease↗
PubMed1992

Nonintegrin laminin receptors in the nervous system: evidence for lack of a relationship to P40.

Laminins are extracellular matrix proteins that mediate their effects on cells through integrin and nonintegrin receptors. Two receptors of 67 and 110 kD that bind laminin with a high affinity (Kd approximately nM) have been reported in neural cells. Here, we discuss these and other nonintegrin laminin receptors that have been implicated in neural function. In addition, we report studies characterizing a 43 kD protein, (P40), immunologically related to the 67 kD laminin receptor, which may be involved in retinal development. In our studies, polyclonal antisera (anti-P-20-A) to a synthetic peptide derived from the sequence of a cDNA for a putative high-affinity laminin receptor (67 kD) detected a protein of 43 kD in immunoblots of adult rat retinas. Immunohistochemistry with this antiserum showed that the retinal immunoreactivity was predominantly localized in the ganglion cell layer of both adult chicken and rat retinas where it appeared to be intracellular. Retinal ganglion cells were shown to be immunoreactive by retrogradely labeling them from the superior colliculus with a lipophilic dye and subsequently with anti-P-20-A antisera. Consistent with the preferential localization of the P-20-A immunoreactivity in ganglion cells, there was a substantial decrease in the amounts of P40 on Western blots following optic nerve section and resulting retinal ganglion cell death. Screening of a rat (PC12 cell) cDNA library with the anti-P-20-A antiserum further confirmed the specificity of the antiserum for the rat homologue of P40. Rat P40 is 97% identical to the mouse and 87% identical to human P40 at the nucleic acid level and 98% at the protein level. Restriction mapping of the rather abundant positive clones in the library that cross-hybridized with a human cDNA probe for P40 indicated that the full-length cDNA of 1.2 kb was the major and perhaps the only cDNA in the library. In Northern blots of adult rat retina, these clones hybridized to a single 1.2-kb transcript. Electroblots of retinal homogenates probed with radioiodinated laminin demonstrated binding to a broad band at 110 kD, but none at 43 kD. Taken together these findings suggest that P40 may not be a laminin receptor and are in keeping with the hydrophilic composition of the protein, its intracellular localization, as well as other features predicted by its nucleic acid sequence.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1992

Genetic mapping of the integrin alpha 1 gene (Vla1) to mouse chromosome 13.

The integrin alpha 1 chain (Vla1) associates with the beta 1 chain to form a heterodimer that functions as a dual laminin/collagen receptor in neural cells and hematopoietic cells. We have used an interspecies backcross gene-mapping technique to map the Vla1 gene to the distal end of chromosome 13 in the mouse genome. The Vla1 locus is located 3.5 cM distal to Ctla-3 and 7.8 cM distal to Htrla. We have further characterized this locus in recombinant inbred (RI) mice by examining the strain distribution patterns of nine genomic DNA restriction fragment length variants detected with alpha 1 cDNA probes. The RI gene mapping did not show linkage to previously mapped genes or mutants in the AXB, BXA, or AKXD RI sets and therefore defines a new genetic marker for the distal end of chromosome 13 in these RI sets.

Animals↗
PubMed1991

Visceral perception in health and functional dyspepsia. Crossover study of gastric distension with placebo and domperidone.

The symptoms of functional dyspepsia are still unexplained. To evaluate the possible role of abnormal visceral perception, we studied the symptomatic responses and the pressure variations during progressive gastric distension in 10 female healthy control subjects (mean age 33.6 years) and in 10 female patients with functional dyspepsia (mean age 35.2 years). A rubber balloon was positioned 4 cm below the lower esophageal sphincter (LES) and inflated with progressively larger volumes of air by steps of 50 ml; pressures at the gastric fundus and at the LES were continuously recorded by perfused manometric catheters. Each subject was studied on two separate occasions after randomized double-blind administration of either placebo or 20 mg of domperidone. Symptomatic responses and the manometric data were analyzed at the time of the initial recognition of distension (bloating step) and at the time of reporting pain or up to a maximum of 700 ml of balloon inflation (pain or 700-ml step). On placebo, the volumes of gastric distension were more than two times lower in patients than in control subjects at the bloating step (185 +/- 32 ml vs 470 +/- 40 ml, P = 0.001) and at the pain or 700-ml step (265 +/- 54 ml vs 600 +/- 34 ml, P less than 0.005), while the pressure gradients (pressure at inflation steps minus baseline pressure before beginning inflation) were not statistically different between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Determination of serum activity of placental alkaline phosphatase].

The authors have developed an enzymatic method for the measurement of serum placental alkaline phosphatase (PLAP) based on the hydrolysis of paranitrophenyl phosphate into para-nitrophenol. The specificity for the isoenzyme involved is achieved by means of its characteristics thermostability. After one hour incubation at 60 degrees C, PLAP still maintains its full activity, while other isoenzymes are completely inactivated. The sensitivity of the method was improved (less than 1 U/l) by optimizing parameters such as the volume of specimen, the nature of the buffer (2-methyl-amino-ethanol), the reaction time and the pH. Analysis of the method performances has revealed a lower detection limit of 0.12 U/l, a linearity from 0 to 50 U/l, a precision lower than 10% for most of the analytical range and a complete enzyme recovery. The reference range was estimated from 0 U/l to 0.33 U/l in a group of 125 non-smokers without any cancerous disease.

Alkaline Phosphatase↗
PubMed1988

Adult celiac sprue: changes in the pattern of clinical recognition.

We report the clinical, laboratory, and pathological findings in a series of 52 consecutive patients with adult celiac sprue observed over a 20-year period. The frequency of that diagnosis increased from an average of 0.7 case/year during the period 1966-1975 to 5.8 cases/year during the period 1981-1985. Apart from two patients with dermatitis herpetiformis, nonclassical clinical presentations were observed in 16 of 50 (32%) patients overall and in 13 of 28 (46%) patients diagnosed since 1981. Diarrhea was the most common complaint leading to the diagnosis; since 1981, hematologic abnormalities warranted investigation in 38% of the patients. Decreased iron stores (88%), decreased red cell folate (82%), or both (74%), and abnormal radiographic studies of the small bowel (83%) were the most sensitive tests in the diagnostic investigation. We conclude that atypical or nonclassical presentations of adult celiac sprue, mostly with hematologic abnormalities, are not uncommon.

Abdomen↗
PubMed1987

Evaluation of the average of patients: application to endocrine assays.

Recent work (Cembrowski et al, Am J Clin Pathol 1984;81:492-499) has shown that the average of selected patient data can theoretically be used to demonstrate systematic errors. We formerly demonstrate that the sensitivity or power of the 'average of patients' (AOP) is related to the index (NpSw2)/Sp2 where Np is the number of patient results averaged, Sw the within-run component of the standard deviation of the analytical method and Sp the standard deviation of the trimmed population. The utility of the AOP can therefore be assessed rapidly without power function curves or the calculation of the daily AOP itself. The index showed that, for 12 radioimmunoassays done in our laboratory, the power of the AOP was greatest for T3 uptake, then FTI, then T4. Daily AOP were followed for these tests with control results on parallel Shewhart plots. We also applied an exponential smoothing procedure on the AOP and control results to improve trend detection. These analyses demonstrated that the AOP can improve the detection of systematic errors and the differentiation of true errors from errors affecting only control specimens.

Endocrine System Diseases↗
PubMed1986

HLA-A,B and DR matching in corneal transplantation.

One hundred eighty-five consecutive corneal transplants were performed in recipients selected on the basis of the best available HLA-A,B and DR match. Endothelial rejection-free transplant survival in this group was compared to a retrospective historical control group of 199 consecutive transplants performed in recipients selected on the basis of age and longest wait criteria. The two groups were comparable with regards to primary diagnosis, preoperative corneal vascularization, donor and recipient age, and operative techniques. Thirty-eight transplants in the study group and 28 transplants in the control group were at high risk for endothelial transplant rejection. At 12 months, the estimated rejection-free survival (Kaplan-Meier method) of the high-risk study group transplants was 87% compared to 74% for the high-risk historical control group and transplants. This difference did not reach the significant level of 0.05 with the log-rank test. The 12-month estimated rejection-free survival of low-risk study group and historical control group transplants were similar. In the study group, the 12-month estimated rejection-free survival of well-matched transplants was 95% compared to 83% for poorly matched transplants (log rank, P less than 0.02). These findings suggest that a relationship exists between HLA-A,B and DR compatibility of donor and recipient and the corneal rejection-free transplant survival.

Corneal Transplantation↗
PubMed1983

Performance of the Hitachi 705 evaluated.

We evaluated a new discrete analyzer, the Hitachi 705. The instrument can process sequentially as many as 19 different enzymes or other analytes, with a throughput of 180 tests per hour. We evaluated the spectrophotometer, the sample and reagent probes, and the performance for 11 assays: creatine kinase, aspartate aminotransferase, alkaline phosphatase, gamma-glutamyltransférase, amylase, glucose, urea nitrogen, creatinine, albumin, calcium, and phosphorus. The total imprecisions (within-day plus day-to-day component of imprecision) (CV) were: for the photometer (six concentrations of potassium dichromate), 0.14 to 0.4%; for the serum probe (55 to 20 microL), 0.4 to 1.0%; for the reagents probes (50 to 350 microL), 0.3 to 1.2%; for the enzymatic procedures, 2.0 to 8.0%; and for the other tests (glucose, urea nitrogen, creatinine), 1.0 to 4.0%. Good linearity was obtained in the proposed range for the 11 tests, except for calcium. Comparison of the total analytical error with the medically allowable error at a decision value showed that the test results were acceptable, except for calcium and phosphorus. The instrument showed good reliability and practicability.

Autoanalysis↗