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Biomedical subjects

M Leroux

Publications and source records attributed to M Leroux.

16 recordsLinked to original sources
PubMed1992

Isokinetic rehabilitation after arthroscopic meniscectomy.

The aim of this study was to assess the effects in humans of early (2 weeks) and delayed (6 weeks) isokinetic strength training in the recovery of muscle strength following an arthroscopic partial meniscectomy. The peak torque developed in the quadriceps and hamstrings and the torque developed at a knee angle of 1.05 rad were evaluated in 16 subjects, pre-operatively (pre-op), and 2, 6, and 10 weeks post-operatively (post-op), on an isokinetic device at four different velocities (1.05, 2.09, 3.14, and 4.19 rad.s-1). The fatigue characteristics of the muscles were evaluated by having the subject perform 15 maximal contractions at 3.14 rad.s-1. Training was done on the same device (three times a week for 1-2 months), beginning either 2 or 6 weeks post-op. A repeated measures analysis of variance demonstrated a time effect but no differences between groups and no interactions. Torques developed by the knee flexors and extensors were significantly smaller 2 weeks post-op than pre-op, at all velocities tested. Torques developed in the quadriceps recovered to their pre-op values by 6 weeks, and further gained significantly in strength from 6 to 10 weeks. Quadriceps torques remained weaker than the contralateral side at 10 weeks. Hamstrings torques were either higher or similar to pre-op values by 6 weeks, and demonstrated increases from 6 to 10 weeks post-op at 1.05 and 4.19 rad.s-1 only. Total work and average power developed by the quadriceps and hamstrings during the fatigue protocol changed with time in a similar manner to torque.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Reversal of defective lymphoproliferation in postoperative patients with colon cancer.

To establish a method for evaluation of immunological parameters in small blood samples, a whole blood technique was developed for the estimation of mitogen- or antigen-induced proliferation. Studies regarding cellular immunity in patients with colon cancer were done with 108 patients in all tumor stages, aged 32 to 80 years. They were studied before surgery and 10 days after operation. A group of 35 patients were further tested 3 months after surgical treatment. In patients with colon cancer the proliferative responses of peripheral blood lymphocytes to mitogens were significantly lower in comparison to healthy controls. These results were found when the response to concanavalin A, phytohemagglutinin, OKT 3, and pokeweed mitogen were analyzed preoperatively and 10 days postoperatively. There was no relation to the stage of disease. The marked reduction of mitogen responses was followed by a gradual return toward normal values 3 months after surgical resection of neoplastic growth in 80% of the patients. Our studies indicate that the defects were largely restored when testing was performed 3 months after operation. Using this result, it will be possible to perform long-term studies in order to establish if there is a correlation between the return to normal immune reactivity and the survival of individual patients.

Adult↗
PubMed1987

[11q trisomy: apropos of 2 cases].

The authors report two new cases of 11q trisomy, one due to a "classical" (11q; 22q) translocation, one due to a desequilibrated (8q; 11q) translocation (de novo). The 2 phenotypes are compared with the data of the literature on the 11q trisomy syndrome.

Chromosomes, Human, Pair 11↗
PubMed1986

Depression of cellular immunity after open-heart surgery.

Using a whole blood test system we investigated cell-mediated immunity in 45 patients undergoing open-heart surgery. The peripheral blood lymphocytes were stimulated with the nonspecific mitogens phytohemagglutinin, concanavalin A and pokeweed mitogen, one bacterial recall antigen, tuberculin PPD, and one viral antigen, herpes simplex virus. The patients were tested three times: pre-operatively, and seven days and 2 wks post-operatively. There were no significant differences between a control group of healthy blood donors and the patient group tested preoperatively. However, seven days after operation we observed a clear decrease of the reactions to all stimulants. Two weeks after operation there was an increase of lymphocyte proliferation data in regard to tuberculin PPD and herpes simplex virus. Concerning the nonspecific mitogens PHA and PWM, there was only a tendency of an increase. We believe that two weeks after operation is too short an interval to notice a full normalization of the cellular immune functions. In comparison with the conventional system of isolated lymphocytes, the whole blood technique is advantageous in investigating cell-mediated immunity, particularly if the patient groups are large.

Adult↗
PubMed1986

Studies of cellular immunity, serum interferon titers, and natural killer cell activity in schizophrenic patients.

In one of the hypotheses on the causes of schizophrenia it is proposed that viruses may play a role in the etiology and pathogenesis of at least some forms of schizophrenia. In our study, 30 healthy adults and 30 schizophrenic patients were investigated for humoral and cellular immunity against herpes simplex virus (HSV) and cytomegalovirus (CMV). A whole blood test system with several advantages over commonly used procedures was used to study cell-mediated immunity to CMV and HSV. Our data showed no difference between serum antibody levels or cellular immunity of the schizophrenic patients and control individuals as far as HSV and CMV were tested. Serum interferon may be indicative for the presence of a yet unidentified virus. Therefore, we tested interferon levels in the serum of patients. No interferon was detected in any of the samples tested. Further, we tested the activity of natural killer (NK) cells in the blood of schizophrenic patients and controls. NK-activity of the patients' blood cells was not different from that of normal donors.

Antibodies, Viral↗
PubMed1986

[Decision strategy: effect of the proportion of total response time taken by choice reaction time].

Results from two series of studies on decision strategies suggested that subjects appeared to chose between two response modes. Subjects could use a decision strategy based either on anticipatory responses or on reaction responses. It appeared that certain characteristics specific to the task could be responsible for the discrepancy in the response mode. The aim of the present study was to ascertain whether the choice of a decision strategy could be dictated by the proportion of total response time taken up by the choice reaction time (TRC). For instance, if the TRC takes up a large proportion of the total time, reducing it in view of an anticipatory response could considerably reduce the total time. The advantage to be gained from an anticipatory response could thus be considered sufficient to warrant adoption of a decision strategy based on anticipation. On the contrary, when TRC takes up only a small portion of total time, a decision strategy based upon reactions is preferred since the cost related to an error in response would largely exceed the advantage related to anticipation. Results from the two series of experiments presented in this paper support the importance of this variable. More specifically, results revealed that the error that an individual allows himself to make depends upon the proportion of total time that is devoted to choice reaction time. An extension of the model presented by Proteau et al. is proposed in order to account for the present observations.

Choice Behavior↗
PubMed1985

A whole-blood lymphoproliferation assay for measuring cellular immunity against herpes viruses.

A whole blood test system was established to study cell-mediated immunity to cytomegalovirus (CMV) and herpes simplex virus (HSV) in a large number of healthy blood donors. Cellular immunity was measured by the in vitro proliferative response (LP) of peripheral lymphocytes. These responded vigorously to several mitogens. Lymphocytes of most individuals responded to HSV, but only a limited number were reactive towards CMV. In parallel, antibodies against CMV and HSV were measured by an ELISA technique. For HSV, good correlation was observed between serological and lymphocyte proliferation results. For CMV, no clear correlation was obtained, only 21 of 40 donors positive in the antibody test being positive in the LP test. The majority of seronegatives were negative in the LP test. Use of virions purified by sucrose gradient centrifugation, or an additional strain of CMV (strain Davis) did not increase the number of donors positive in the LP test. One explanation might be that individuals possessing antibodies against CMV as measured by ELISA but no capacity to react in the LP test had suffered from a CMV infection a long time before, and now showed waning cellular immunity, but antibody still detectable. Use of the whole blood technique on 108 individuals showed that this very simple test works well with various mitogens and at least some antigens.

Antigens, Viral↗
PubMed1985

Proliferation and interferon production in whole blood samples and isolated lymphocyte preparations.

To establish a method for the evaluation of immunological parameters in small blood samples, a whole blood technique was developed for the estimation of mitogen induced cell proliferation and interferon (IFN) production. The results obtained were compared with data using isolated peripheral blood lymphocytes (PBL). Mixtures of heparinized whole blood and culture medium or equal numbers of PBL of healthy volunteers or of patients were cultured with the mitogens concanavalin A, phytohemagglutinin, pokeweed mitogen or the monoclonal antibodies OKT3 and anti-Leu-4. Cell proliferation as measured by 3H-thymidine incorporation and interferon production were found to be of higher magnitude in the whole blood assay. The only situation in which results were similar was pokeweed mitogen induced cell proliferation. Since in the whole blood assay the cell populations are present in their natural distribution, this test system may reflect the in vivo situation better than the test using isolated lymphocytes. Furthermore, our data indicate that whole blood samples may be used clinically for the evaluation of different immune parameters, as data on a limited number of patients with Hodgkin's disease have shown.

Antibodies, Monoclonal↗
PubMed1985

Decreased production of interferon alpha and interferon gamma in leucocyte cultures of schizophrenic patients.

In a first approach to measure the activity of the interferon system in schizophrenic patients, leucocyte cultures of schizophrenic patients and normal control individuals were set up using a whole blood assay. In this system both lymphoproliferation and the induction of interferon was tested. The lymphoproliferation (LP) test was performed with one bacterial recall antigen (PPD) and four different mitogens (phytohemagglutinin (PHA), concanavalin A (Con A), pokeweed mitogen (PWM) and a novel mitogen derived from mycoplasma arthritidis - MAS). For induction of interferon two inducers of interferon alpha (Corynebacterium parvum and Newcastle disease virus (NDV] and two inducers of interferon gamma (PHA and Con A) were tested. Leucocytes of the patients responded to C. parvum, NDV and Con A with significantly lower titers of interferon, whereas the responses to PHA were lower than those of normals, but this difference was not significant. Regarding the LP test, significantly lower responses of the patients were obtained with PHA and Con A, whereas there were no significant differences when the responses to MAS, PWM or PPD were compared. Although our data cannot rule out a role of the medications in the defects observed, they may be indicative of a defect in the interferon system of schizophrenic patients.

Adult↗
PubMed1985

Proliferative responses to human cytomegalovirus in lymphocyte cultures of male homosexuals.

29 healthy adults and 32 male homosexuals were investigated for their humoral and cellular immunity against human cytomegalovirus (HCMV). In contrast to 30% of the controls, all homosexuals had HCMV serum antibodies. In addition, 84% of the homosexuals reacted positively in HCMV induced in vitro lymphocyte proliferation as compared to 66% of the controls. The study group also showed significantly higher mean reactivities in the lymphoproliferative response towards HCMV. In the group of homosexuals, a correlation could be established between the humoral and cellular immune reactivity to HCMV.

Adult↗
PubMed1979

Decrease in lung recoil pressure after cessation of smoking.

Tests of lung mechanics and single-breath carbon monoxide diffusing capacity (DLCO) were done in 26 apparently healthy cigarette smokers before and 2 months after cessation of smoking. There was a significant increase in vital capacity and 1-sec forced expiratory volume as well as improvement in frequency dependence of lung dynamic compliance. Slope and phase III and density dependence of maximal expiratory flow showed a borderline improvement DLCO did not change. Static lung pressure-volume curves showed a small but significant (P less than 0.01) shift toward lower pressures. We concluded that the previously reported decrease in lung recoil pressure observed in smokers is even more accentuated after cessation of smoking.

Adult↗
PubMed1977

Measurement of creatine kinase Z in human sera using a DEAE-cellulose mini-column method.

A DEAE-cellulose mini-column method has been developed which allows for the quantitation in human serum of creatine kinase Z, a sub-band of creatine kinase first described by Lim ((1975) Clin. Chem. 21, 975, Abstract 181) and Sax et al. (Sax, S.M., Moore, J.J., Giegel, J.L. and Welsh, M. (1976) Clin. Chem. 22, 87). We have shown that creatine kinase Z is rather unstable in nature, and converts to a form which electrophoreses with creatine kinase MM on agarose gel electrophoresis. CK-Z is not present in normal human serum. CK-Z is present in human heart extracts, in patients with myocardial infarcts and in patients with skeletal muscle trauma. In infarct patients CK-Z levels paralleled changes in the CK-MB levels. CK-Z ranged in activity from 8.8-67.2 I.U. whereas CK-MB ranged from 29.6-121.6 I.U. in infarct patients. CK-Z and CK-MB activity were measured at or close to the peak rise in total CK activity.

Brain↗
PubMed1975

The early detection of airway obstruction.

To assess the sensitivity of tests for early, small airway obstruction, we selected 52 cigarette smokers with a ratio of 1-sec forced expiratory volume to forced vital capacity greater than 70 per cent from a smoking cessation clinic. From these subjects, 29 of the 46 tested demonstrated frequency dependence of dynamic compliance, a finding arbitrarily defined as indicative of small airway obstruction in this group. Dynamic compliance was correlated with the British Medical Research Council questionnaire, routine pulmonary function tests, closing volume as a per cent of vital capacity, maximal expiratory flow-volume curves, and flow dependence of distribution of inhaled boluses of xenon-133 (finite difference Xe). Symptoms of respiratory disease, and abnormal flow-volume curves, specific conductances, and ratios of residual volume to total lung capacity were also present in some subjects, but they correlated very poorly with frequency dependence of dynamic compliance. On the other hand, finite difference Xe was abnormal in 85 per cent of cases with frequency dependence of compliance and closing volume was abnormal in 70 per cent. In 8 of 12 subjects restudied 2 months after they stopped smoking, dynamic compliance was less frequency dependent than before smoking cessation. Similar improvements were noted in finite difference Xe, but closing volume was unchanged. Although closing volume and dynamic compliance tended to be abnormal in the same subject, concordance was not excellent, and the effects of smoking cessation suggested that the 2 tests had different determinants.

Adult↗
PubMedDate not supplied

A multivariable analysis of factors governing the steady-state pharmacokinetics of valproic acid in 52 young epileptics.

A number of factors have been implicated in the interpatient variability of valproic acid (VPA) pharmacokinetics. These include patient age, concurrent anticonvulsant therapy, and dosage of VPA. In the clinical setting, it is important to determine which of these variables exert a major effect on the observed differences in VPA disposition. Accordingly, we analyzed the data from 52 young epileptic patients using multivariate statistical methods. Concurrent anticonvulsant therapy was the major determinant of VPA clearance in this patient population. The half-life of VPA was significantly related to age, but volume of distribution and clearance were not. The dosage of VPA affected the volume of distribution of VPA but not the half-life or clearance of this drug. These results provide a more rational understanding of VPA pharmacokinetics in the clinical setting and have implications for the monitoring and manipulation of VPA therapy in the epileptic population.

Adolescent↗