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Biomedical subjects

B Petit

Publications and source records attributed to B Petit.

At least 55 records · Page 3Linked to original sources
PubMed1994

Reproducibility of running time to exhaustion at VO2max in subelite runners.

The purpose of this study was to assess the reproducibility of running time to exhaustion (Tlim) at maximal aerobic speed (MAS: the minimum speed that elicits VO2max), on eight subelite male long distance runners (29 +/- 3-yr-old; VO2max = 69.5 +/- 4.2 ml.kg-1.min-1; MAS = 21.25 +/- 1.1 km.h-1). No significant differences were observed between Tlim measured on a treadmill at a 1-wk interval (404 +/- 101 s vs 402 +/- 113 s; r = 0.864); however, observation of individual data indicates a wide within-subjects variability (CV = 25%). In a small and homogenous sample of runners studied, exercise time to exhaustion at MAS was not related to VO2max (r = 0.138), MAS (r = 0.241), running economy (mlO2.kg-1.min-1 at 16 km.h-1) (r = 0.024), or running performance achieved for 3000 m (km.h-1)(r = 0.667). However, Tlim at MAS was significantly related to the lactate threshold determined by the distinctive acceleration point detected in the lactate curve around 3-5 mmol.l-1 expresses in %VO2max (r = 0.745) and to the speed over a 21.1-km race (km.h-1) (r = 0.719). These data demonstrate that running time to exhaustion at MAS in subelite male long distance runners is related to long distance performance and lactate threshold but not to VO2max or MAS.

Adult↗
PubMed1993

Ultrastructural organization of type XI collagen in fetal bovine epiphyseal cartilage.

Type XI collagen was localized with polyclonal antibodies specific for alpha 1 (XI) and alpha 2 (XI) chains in the resting zone of epiphyseal cartilage from calf fetuses. The immunofluorescence technique was used on sections of cartilage, and the immunogold labelling technique for electron microscopy on fibrils isolated from cartilage and, for the first time, in situ on blocks of cartilage fractured in liquid nitrogen. Immunofluorescence showed that without pepsin treatment the staining of type XI collagen was restricted to the pericellular zones; after pepsin treatment, the staining was co-distributed with that of type II collagen. Immunoelectron microscopy performed on isolated fibrils and on cartilage blocks showed that after disruption of fibrils with pepsin, type XI collagen was labelled on small filaments on the fibrils. When the fibrils were not disrupted, labelling was observed in situ only at the ends of the fibrils or on cross-sections of some fibrils. These results indicate that type XI collagen is located inside type II collagen fibrils in fetal bovine epiphyseal cartilage, as already postulated for embryonic chicken sterna.

Animals↗
PubMed1993

[Somatosensory evoked potentials during spinal orthopedic surgery in adult patients].

Somatosensory evoked potentials (SEPs) were recorded in 165 patients from 185 operations for scoliosis and major spinal distortions, lumbar or cervical stenosis, post-traumatic malunions, or tumors. They were obtained by percutaneous stimulation of right and left median and tibial posterior nerves, and recorded on the scalp as recently, motor potentials (MPs) have also been obtained, by a trans-spinous stimulation rostral to the level of intervention. The protocol consists of pre- and post-operative recordings, as well as a continuous intra-operative monitoring. Neuromonitoring is justified in operations implying neurological risks, particularly scoliosis. A durable disappearance of SEPs and MPs was always associated with post-operative neurological disorders. Transient disappearances, not associated with neurological disorders, have been observed during certain manoeuvres such as vertebral traction, osteosynthesis, placing trans-pedicular screws or hooks, leading the surgeon to modify the operation. The role of medullary ischemia on the degradation of electrophysiological signals, obvious in cardiovascular decompensations, seems predominant in the post-operative occurrence of neurological impairment. During the post-operative period, SEPs allow one to discriminate between organic disorders and subjective complaints; they help in diagnosing hematomas, and distinguish between radicular and spinal cord injuries.

Adolescent↗
PubMed1993

Composition and organization of the collagen network produced by fetal bovine chondrocytes cultured at high density.

Fetal bovine chondrocytes isolated from the resting zone of epiphyseal cartilage were maintained in high-density culture for 4 weeks. From Day 2 in culture, the chondrocytes deposited an extracellular matrix composed of Types II, IX, and XI collagen. Types IX and XI collagen were restricted to the pericellular domain from Day 5. By 2 weeks the entire cell layer stained for antibodies to Type II and IX collagens. Type XI could be demonstrated throughout the cell layer by pepsinization of the sections. Results from both rotary shadowing and immunochemistry showed that the fibrils formed in culture were heterotypic, with Type IX collagen arranged along the surface and with Type XI collagen buried in Type II fibrils. Nonspecific Type VI collagen and the glycoproteins tenascin and fibrillin, previously described in cartilaginous tissue, were identified by their ultrastructural characteristics in the cell layer homogenate. Although the cells presented morphological characteristics of chondrocytes and still expressed cartilage-specific collagens, the appearance of Type I collagen in the culture cell layer after 4 weeks of culture demonstrates a partial dedifferentiation of the chondrocytes. The culture system described in this report provides an interesting tool for maintaining chondrocytes in a cartilage-like matrix to study the influence of different physical and chemical factors on the expression and differentiation of the cells.

Animals↗
PubMed1990

Submandibular gland tumors. Adverse histologic factors and therapeutic implications.

We reviewed our 41-year experience with tumors of the submandibular gland to determine what factors influence outcome and their implications for treatment. The most common benign neoplasm was pleomorphic adenoma (21), while among malignant tumors the adenoid cystic variety (37) predominated. For the 86 patients who had malignant tumors, the 2- and 5-year survivals by the life table method were 82% and 69%, respectively. For patients with malignant tumors, histology, size, perineural invasion, and prior treatment did not affect overall survival. Factors adversely affecting outcome were extraglandular soft-tissue extension and lymph node metastasis. Local-regional control was enhanced in patients with soft-tissue extension if they were treated by surgery followed by radiotherapy rather than by surgery alone.

Adenocarcinoma↗
PubMed1986

[Vascular malformations of the colon. A frequently undetected etiology of lower digestive hemorrhage].

Angiectasia of the right colon is a new entity which must be considered in cases of lower intestinal haemorrhage. Moore's classification is the one that is generally accepted today; it distinguishes between 3 types the most interesting and best individualized of which is type I. It consists of acquired lesions occurring after the age of 60, often multiple, localized in the right colon and frequently associated with aortic stenosis and atheroma. The diagnosis of these vascular malformations is usually delayed because the lesions are submucosal and not visible at endoscopy. Bimesaraic arteriography may show typical images where extravasation of contrast medium is associated with vascular tuft or "tuff". Even the anatomicopathological confirmation of the diagnosis is difficult, since the lesion can only be located by special techniques, such as intra-arterial injection of a silicone-containing substance. Owing to the failure of modern techniques such as embolization, the only possible treatment is surgical, based on resection of the colonic segment involved.

Arteriovenous Malformations↗
PubMed1983

[Automatic recording of venous hysteresis. Results in the normal subject and in varicose patients].

The measurement of the venous distensibility by straingauge plethysmography during a semi-continuous variation (3 mm Hg every 20 seconds) of the cuff pressure during its inflation from 0 to 100 mm Hg and its deflation allow to record the venous hysteresis and to determine accurately the venous pressure. The standardized and automatic (Periflow J.S.I.) new method is highly discriminative between controls and varicose patients.

Adult↗
PubMed1981

Hyperplasia of the exocrine pancreas after small bowel resection in the rat.

The effect of a 90% small bowel resection on the exocrine pancreas was investigated over a three month period in adult Wistar rats. Control animals underwent a sham-resection consisting of a transection and reanastomosis of the small intestine. After jejunoileal resection, the wet weight of a gland increased significantly (52%) from the 15th day. The parallel increase in total protein, DNA and RNA content without any modification in the ratios of pancreatic weight, protein, and RNA to DNA suggests that there is cellular hyperplasia but not hypertrophy. Small intestinal resection decreased significantly the amount of amylase when expressed per unit pancreatic weight; it reduced slightly but not significantly that of chymotrypsin, while it did not modify the amount of lipase. However, the total amount of these enzymes in the pancreas remained unaltered when compared with controls. It is concluded that a massive resection of the small bowel induces cellular hyperplasia in the rat exocrine pancreas; this could compensate that reduced level of enzymes in acinar cells.

Adaptation, Physiological↗
PubMed1980

The therapeutic efficacy of human immunoglobulins as a function of their in vitro antibody activity toward circulating antigens in children with recurrent infections of the upper respiratory tract.

Children with recurrent infections of the upper respiratory tract were treated by injections of human immunoglobulins. Of the 58 children who were followed after treatment, the clinical outcome and the results of laboratory tests, i.e. serum protein profile and level of circulating immune complexes, were improved in 33. The improvement was significantly related to the in vitro antibody reaction of the immunoglobulin batch that was used for injections with unidentified antigens present, before treatment, in the patient's serum.

Antigen-Antibody Complex↗
PubMed1979

Fetal breathing patterns in intrauterine growth retardation.

Fetal breathing movements were studied with real time ultrasound in 21 normal fetuses and 30 fetuses born small-for-dates (less than the 5th centile). The events of the study period were recorded on punched paper tape which was subjected to computer analysis. In the normal group the percentage time of breathing was 54 +/- 12.7 (mean +/- SD). The breath to breath interval was 1.34 +/- 0.25 seconds and the coefficient of variation of this interval was 49.6 +/- 7.7 per cent. In 17 of the small-for-dates group amount of breathing was reduced with short breathing episodes and long apnoea intervals. In the other 13 patients in the small-for-dates group the coefficient of variation for the breath to breath interval was significantly reduced (39.6 +/- 7.9 per cent, p less than 0.01).

Female↗