PubMed Health⌕ Search

Biomedical subjects

M Bonnard

Publications and source records attributed to M Bonnard.

At least 37 records · Page 2Linked to original sources
PubMed1992

Steady-state fluctuations of human walking.

In steady-state walking, fluctuations in space-time behavior are observed for normal adult subjects. In the present study, the intrinsic fluctuations of gait have been analyzed when walking on a subject-driven treadmill (with adjustable inertial forces). Furthermore, these intrinsic fluctuations have been compared with those observed in natural overground locomotion which involves a real subject's displacement and thus an optical flow. Four adult subjects participated in both experimental sessions. It was found that the frequency and amplitude of the instantaneous fluctuations of leg movement were weak and of equal magnitude with or without optical flow. This was also the case for instantaneous fluctuations in displacement speed. Secondly, a low-frequency fluctuation in walking speed was observed when no optical flow information was available to the subject. This fluctuation results from the addition of a series of leg-movement fluctuations, whose values are all either positive or negative. As the optical flow provides information about the displacement speed, it allows the subject to avoid such addition, and thus plays a role in maintaining steady leg movement. Theoretical models linking space-time behavior of rhythmic movement with stiffness strongly suggest that the observed low-frequency fluctuations in speed result from fluctuations in stiffness.

Adult↗
PubMed1992

[Study of the immune profile of pregnant women].

During pregnancy, the fetus is an hemiallograft perfectly tolerated by the mother. With the aim of elucidating the mechanism of this tolerance, we have looked to see whether lymphocyte subsets are modified by pregnancy. Using monoclonal antibodies and flow cytometry, we have studied the changes in the immune profile of normal pregnant women and compared them with non pregnant women. In pregnant women, a significant decrease in the percentage of CD3+ cells is observed in the first trimester (61.1 +/- 14.7% versus 73.8 +/- 6.8%; p less than 0.001). The same data are obtained for CD4+ cells (38.2 +/- 10.7% versus 44.0 +/- 7.0%; p less than 0.05) and CD8+ cells (22.8 +/- 5.6% versus 28.0 +/- 8.9%; p less than 0.05). On the other hand, B lymphocytes (CD19+), monocytes (Leu M3+) and natural killer (NK) cells (Leu7+) remain stable during pregnancy. CD11a+ cells decreased during the 1st and 2nd trimesters. Lastly, activated T lymphocytes (CD3+DR+, CD8+DR+) are not modified. Using absolute numbers, a significant decrease is shown only for CD3+ cells in the 2nd and 3rd trimesters and for CD11a+ cells in the 2nd trimester of pregnancy. The decrease of T lymphocyte subsets, NK and CD11a+ cells during pregnancy partially explains the tolerance for the fetus.

Antigens, CD↗
PubMed1991

[Prevention of late post-traumatic epilepsy by phenytoin in severe brain injuries. 2 years' follow-up].

The high incidence rate and the invalidating nature of post-traumatic epilepsy after severe brain injury have encouraged the authors to review the prophylactic treatment of this type of epilepsy. Thirty-four out of 86 randomised patients with brain injuries admitted into a neurotraumatology intensive care unit were treated prophylactically, immediately after the injury, with an intravenous hydantoin injection in a dose sufficient to provide stable and effective blood levels. This was followed by dose-adjusted oral administration maintained for a minimum period of 3 months. After a 2 years' follow-up, there was a significant difference between treated and untreated patients, since only 6 per cent of the patients treated suffered from post-traumatic epilepsy, as against 42 percent in the untreated group.

Adolescent↗
PubMed1991

Insulin prevents adoptive cell transfer of diabetes in the autoimmune non-obese diabetic mouse.

Early intensive insulin treatment is thought to improve subsequent Beta-cell function in Type 1 (insulin-dependent) diabetic patients. Prophylactic insulin administration also reduced diabetes incidence in diabetes-prone animals. To study the mechanisms by which these effects occur, we tested the ability of insulin therapy in the model of non-obese-diabetic mice, to prevent the penetration of committed T cells into the islets and subsequent Beta-cell destruction. Sublethally irradiated non-obese-diabetic males of 8 weeks of age were adoptively transferred with splenocytes from diabetic donors and treated with the maximum tolerable dosage of fast-acting insulin (0.5 U, twice daily) until 30 days after cell transfer. Diabetes incidence was compared to control animals injected with the same concentration of insulin diluent. After one month of treatment, the cumulative diabetes frequency was significantly less within the insulin-treated group (4 of 15, 26.6%) than in the control group (15 of 18, 83.3%; p less than 0.01). Pancreatic histological analysis of insulin-treated animals revealed a lower severity of insulitis and Beta-cell necrosis and a higher percentage of normal islets (46.6 +/- 10% vs 2.3 +/- 2%, p less than 0.01), including five (33%) mice with no lesions. Immunoperoxydase staining of pancreatic sections indicated similar insulin and ganglioside staining of Beta cells from insulin-treated mice and control animals. Insulin-treated mice had comparable pancreatic insulin content to normal mice. Flow cytometry analysis of spleen cell populations indicated that insulin increased the number of Thy1,2+ and Lyt-2+ T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Intentional compensation for selective loading affecting human gait phases.

The locomotor strategies used by 12 subjects, instructed to hold their walking speed constant, were examined under various dynamic conditions in order to determine the means by which subjects can act upon their basic locomotor synergy. The dynamic conditions were modified either by adding a load or applying an impeding force. These modifications were designed to selectively affect either the stance phase or the swing phase. The results show that (a) subjects were able to rapidly calibrate their efforts to hold their walking speed constant, (b) in all conditions, the same walking speed was achieved with the same stride lengths and durations, and (c) at the within-cycle level, a change in duration synergically affected both phases and not just the perturbed one. The above results are discussed in terms of intentionally controlled parameters. Because cadence is closely linked to walking speed, it can be used as feedback; the control of walking speed in our experiments may thus be achieved simply by increasing the exerted force until the same cadence is produced.

Journal Article↗
PubMed1990

Phenotypic analysis of a large number of normal human bone marrow sample by flow cytometry.

Bone marrow aspirates from 48 healthy donors (34 adults, 14 children) were analyzed by flow cytometry (FACS Analyzer) after purification of low-density bone marrow cells (Ld BMC) on a density gradient (d = 1,077) and labelling with 23 anti-hematopoietic cell monoclonal antibodies. Based on physical properties, these Ld BMC could be divided into four different populations called E, My, Mo and L, which comprised 14% +/- 9%, 31% +/- 16%, 10% +/- 5% and 45% +/- 14% of these cells, respectively. The phenotypic analysis of these different populations enabled the identification in E, of erythrocytes (Glycophorin A+, Rhesus D+, but negative for early erythroid differentiation markers such as the transferrin receptor (Tf. R) and the FA6-152 antigen); in My of cells of the myeloid lineage (VIM2+, HLA DR-); in Mo of cells of the monocytic lineage (VIM2+, CD14+) plus some myeloblasts (VIM2+, CD14-, HLADR+) and finally in L of a heterogeneous population including: 1. T lymphocytes labelled to the same extent by CD2, CD3, CD5 and CD6 (28% +/- 10%), B lymphocytes assessed by CD19 and CD20 (12% +/- 8%), Pre-B cells (CD10+ = 8% +/- 7%), less than 5% of "natural killer" cells (CD16+ or Leu7+) and finally, less than 6% of myelomonocytes (CD14+ and/or VIM2+). 2. The erythroid lineage (rhesus D+ = 42% +/- 20%, Tf.R+ and FA6-152+ = 32% +/- 12%). 3. Undifferentiated cells or progenitor cells (CD34+ = 7% +/- 5%). 4. Cells unlabelled by any antibodies (approximately 6%). We observed no difference between bone marrow samples from adults or children, with respect to physical properties, and with all but four immunological markers. A significantly higher proportion of B cells (CD19+ and CD10+) (P less than 0.001) and undifferentiated cells (CD34+ and HLADR+) (P less than 0.02) was observed in children. These data, obtained from a large number of bone marrow samples, could be used to quantify the imbalance of some bone marrow disorders.

Adolescent↗
PubMed1989

Quantitative analysis of cultured thymic reticulo-epithelial cells labelled by different antibodies: a flow cytometric study.

Quantitative measurements of cultured human and murine thymic, and human thymoma reticuloepithelial cells (REC), immunolabeled by different antibodies (Ab) (TE3, TE4, anti-HTLV p19(p19), lu5, K11 and Aks) and by thymic hormones (thymulin and thymosin alpha 1 (Ta1)) within these cells, were performed using a flow cytometric technique. The anti-keratin polyclonal Ab labeled nearly the whole human or murine population. The p19 monoclonal Ab (MoAb), specific for the subcortical/medullary thymic regions, labelled 37-77% of the human REC. The TE3 MoAb, specific for the cortical region, labelled 54-83% of the REC. These percentages suggest that the cultured thymic REC (TREC) had markers of both regions together and therefore that these markers are not absolutely specific to determine their subcortical/medullary or cortical thymic origin. For the three populations there were more cells containing Ta1 than thymulin. The overlap of the percentage of labelled cells suggests that the same cell could synthesize the two hormones and that these hormones could be localized within the TE3 positive cells.

Animals↗
PubMed1988

[Analysis of bone marrow by flow cytometry: morphologic and immunologic aspects].

Bone marrow aspirates from 28 healthy donors (18 adults, 10 children) were analysed by flow cytometry (FACS analyser) after purification of low density bone marrow cells (Ld BMC) on a density gradient (d = 1,077) and labeling with 23 anti-hematopoietic cells monoclonal antibodies. Based on physical properties the Ld BMC could be divided into four different populations called E, My, Mo et L including 13 +/- 8%, 33 +/- 15%, 12 +/- 5% and 42 +/- 14% of these cells respectively. The phenotypic analysis of these different populations allowed us to identify in E, erythrocytes (glycophorin A+, Rhesus D+ but negative for early erythroid differentiation markers like the transferrin receptor and/or the FA6-152 antigen); in My, the myeloid lineage (VIM2+, HLADR-); in Mo, the monocytic lineage (CD14+) and some myeloblasts (CD14-, VIM2+, HLADR+) and finally in L, an heterogeneous population including: 1) leucocyte cells, in which 27.3 +/- 9.0% are T cells labelled to the same extent by CD2, CD3, CD5 and CD6, 13.2 +/- 5.9% are B cells assessed by CD19 and CD20, 8.3 +/- 5.7% are Pré-B (CD10+), less than 5% are "natural killer" cells (CD16+ or Leu7+) and finally less than 6% are myelomonocytes (CD14+ or VIM12); 2) the erythroid lineage (Rhesus D+ = 43.7 +/- 12.9%, transferrin receptor and FA6-152+ 36.7 +/- 9.6%); 3) undifferentiated cells or progenitor cells (CD34+ = 6.5 +/- 3.5%); 4) cells unlabelled with any antibodies (approximatively 6%). We have not observed difference between adults and children bone marrow in regard to physical properties properties and all but also immunological markers. Indeed, a significant (p less than 0.02) higher proportion of B cells (CD19 and CD10) was observed in children. These data get from a large number of bone marrow could be used to quantify the imbalance of some bone marrow disorders.

Adolescent↗
PubMed1987

[Diagnostic and therapeutic problems of osteomeningeal defects and traumatic cerebrospinal fluid defects of the anterior floor of the base of the skull. Apropos of 95 cases].

The authors here report teaching drawn from the latest ninety five cases of osteo-dural defects in basilar skull fractures they have surgically treated. They particularly insist on the following points: Difficulties in establishing a clinical diagnosis when the traumatism is in its acute stage: initially 55% of patients do not show any symptom of rhinorrhea, so that the diagnosis is only based on X-ray data. Previous to any surgical treatment the number of serious septic meningitis is rather high in as much as it reaches 10.55% in this series. Risk of infection together with bone damages incite the authors to suggest a surgical treatment of dural defects in their acute stage, namely within the two weeks following the accident. The study of results shows that due to treatment complications, are not insignificant. The authors then tackle the problems of technics and osteo-dural restoration. They, at last, explain, in this series, the interest of preventive antiepileptic treatment by hydantoins during and after the operation. Despite complications due to treatment the results in this series appear to be significant enough to allow the authors to place the indication of the surgical treatment of traumatic osteo-dural defects in basilar skull at the acute stage of their evolution.

Bone Transplantation↗
PubMed1984

[Comparative hemodynamic effects of midazolam and flunitrazepam in head injury patients under controlled ventilation].

The haemodynamic effects of midazolam were compared with those of flunitrazepam in 10 patients with severe head injury under controlled ventilation. Right atrial pressure, pulmonary pressure, pulmonary capillary wedge pressure and cardiac output were measured using a Swan-Ganz thermodilution catheter. Arterial pressure (Pa) was recorded by radial arterial canulation. All patients in this cross-over study received midazolam (0.15 mg X kg-1) and flunitrazepam (0.02 mg X kg-1) intravenously randomly, with 24 h between the two injections. The measurements were first carried out before and then 5, 10, 20, 30 and 60 min after injection. The only significant variations after midazolam and flunitrazepam were a fall in Pa (from 93 +/- 12 to 81 +/- 11 mmHg for midazolam and from 89 +/- 14 to 78 +/- 20 mmHg for flunitrazepam) and in cardiac index (from 4.80 +/- 1.03 to 4.17 +/- 1.14 l X min-1 X m-2 for midazolam and from 5.18 +/- 1.32 to 4.54 +/- 1.03 l X min-1 X m-2 for flunitrazepam). The small decrease in heart rate was not significant. The cardiovascular changes after midazolam and flunitrazepam were small and similar for both drugs. It seemed that midazolam and flunitrazepam were safe for sedating head injured patients under controlled ventilation.

Adult↗
PubMed1984

[Early per- and postoperative epileptic seizures during operations on osteomeningeal breaches. Value of preventive treatment with hydantoins].

The value of prophylactic anti-epileptic treatment in surgery of osteomeningeal breaches has been studied. This surgery exposes to a high risk of seizures, 20 to 25 of our cases after conventional surgery. 74 operated cases of osteomeningeal breaches, among then 38 under preventive anti-epileptic therapy are reviewed. The pre and postoperative epileptic fits up to 24 hours after the operation were taken in consideration.

Craniocerebral Trauma↗
PubMed1980

Glutamine metabolism in isolated dog kidney tubules: inhibition by dialysed albumin preparation.

The metabolic fate of L-glutamine (1 and 5 mM) was studied in isolated dog kidney tubules. At 1 and 5 mM substrate concentration, and after 60 min of incubation, glucose represented 40% and 25% of the glutamine removed; the glutamine unaccounted for (which was probably completely oxidized) represented about one-half and one-third of glutamine removal at 1 and 5 mM glutamine concentrations, respectively. Due to contaminating fatty acids, addition of dialysed bovine serum albumin (fraction V) greatly altered the metabolic fate of glutamine. This observation emphasizes the need for using albumin with great caution for experiments with kidney tubules.

Albumins↗
PubMed1978

Lactate and pyruvate metabolism in isolated renal tubules of normal dogs.

The kinetics of lactate and pyruvate (1 and 5 mM in each case) metabolism was studied in isolated dog renal tubules. Utilization of these two substrates and the production of glucose, pyruvate, or lactate, and alanine were determined. The rates of lactate and pyruvate utilization and of glucose production were constant during 60 min of incubation. Glucose production from pyruvate was less than that from lactate. Addition of albumin to the incubation medium greatly inhibited lactate and pyruvate utilization at both substrate concentrations. It stimulated, however, glucose production from 1 mM, but not 5 mM, lactate or pyruvate. These effects were found to be due to the presence of fatty acids in the albumin solution used. In the absence of fatty acids, glucose production represented 35 to 40% of lactate uptake, but represented less than 20% of pyruvate uptake. Fatty acids markedly enhanced the percentage of transformation of lactate and pyruvate into glucose, and that of pyruvate into lactate. Alanine represented 20% or less of lactate and pyruvate uptake. These results suggest that fatty acids have a regulatory influence on lactate and pyruvate dog kidney metabolism.

Alanine↗
PubMedDate not supplied

T lymphocyte disorder after Capnocytophaga ochracea endocarditis.

Capnocytophaga species are gram-negative rods which may cause disease in both non-immunocompromised and immunocompromised hosts. We describe a case of endocarditis due to Capnocytophaga ochracea in a non-immunocompromised patient with a decrease of blood CD4/CD8 ratio and lymphocyte proliferative response to ConA during infection. In vitro experiments showed that C. ochracea decreased lymphocyte proliferation to mitogens (ConA, PHA), cell surface CD4 antigen and IL2 receptor expression on peripheral blood mononuclear cells (PBMC) from normal volunteers.

Capnocytophaga↗