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Biomedical subjects

M Germain

Publications and source records attributed to M Germain.

At least 19 recordsLinked to original sources
PubMed1992

Pre-acclimatization to high altitude using exercise with normobaric hypoxic gas mixtures.

Pre-acclimatization was conducted using a new method elaborated in our laboratory, combining high intensity exercise while breathing hypoxia normobaric gas mixtures. The training consisted in a daily training during three weeks, 6 days a week, two hours a day, on bicycle ergometer. Eighteen subjects aging 22.2 +/- 1.4 years (11 males, 7 females) were matched in two similar groups: one group trained in normoxic conditions (NG) while the other group (HG) trained with a progressive decrease of the fraction of inspired oxygen (from 12.2% to 10.0%). Maximal oxygen uptake (VO2max) were measured before and after the protocol period in both hypoxic (VO2max H, FIO2 = 10.4%) and normoxic (VO2max N) conditions, for the 2 groups. Training induced a similar O2max N increase in the two groups. The ratio VO2max H/VO2max N was calculated. As expected, in NG group, this ratio decreased significantly (from 63.9 +/- 4.3 to 57.5 +/- 3.1%, p < 0.01) after the training period compared to the initial value, diminution associated with an elevation of VO2max N (from 48.4 +/- 9.0 to 52.9 +/- 9.0 ml.min-1 x kg-1, p < 0.01). Conversely, in HG group, this ratio was not significantly diminished (from 61.7 +/- 3.8 to 60.5 +/- 5.2%, NS) in spite of a similar increase of VO2max N (from 47.5 +/- 5.5 to 50.7 +/- 4.9 ml.min-1 x kg-1, p < 0.01). This does not follow the diminution of the ratio usually described when VO2max N reach higher values.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗
PubMed1992

Converting-enzyme inhibitors potentiate bradykinin-induced relaxation in vitro.

Experiments were designed to study the effects of converting-enzyme inhibitors (captopril and S 10211) on the endothelium-dependent relaxation to bradykinin in isolated porcine arteries. Rings of femoral arteries with and without endothelium were suspended in organ chambers to record isometric tension. Rings of coronary arteries without endothelium were used as bioassay tissue to record release of endothelium-derived relaxing factor (EDRF) from perfused femoral arteries. In organ chambers, bradykinin induced endothelium-dependent relaxation and, inconsistently, endothelium-independent contraction of the femoral artery rings. The relaxation is mediated by endothelial B2 bradykinin receptors, the contraction through B1 bradykinin receptors. Converting-enzyme inhibitors induced a weak potentiation of the contractile response and weak or no potentiation of the endothelium-dependent relaxation. In the presence of indomethacin, the response to bradykinin was not modified and no potentiation from the inhibitor could be observed. Blockade of the contractile response with a B1 bradykinin antagonist did not unmask a potentiation of the bradykinin endothelium-dependent relaxation by the converting-enzyme inhibitors. However, in the presence of B2 bradykinin antagonist, when high concentrations of bradykinin are required to induce relaxation, converting-enzyme inhibitors potentiated the effects of bradykinin. In contrast, in bioassay conditions with a perfused vascular segment, converting-enzyme inhibitors selectively enhanced the release of EDRF by bradykinin. This effect is observed in the bioassay tissue and in the donor segment. These results suggest that converting enzyme is indeed a powerful modulator of bradykinin action and that other enzymatic pathways of bradykinin metabolism present in the vascular wall could mask its action.

Acetylcholine↗
PubMed1992

[Distal arterial bypass surgery for lower limb salvage].

From 1988 to 1990, 34 operations for distal arterial revascularization aimed at lower limb salvage were carried out in 29 patients with arteritis lesions at stage IV with distal necrosis (52%), severe stage III arteritis (10%), severe acute or subacute ischemia (38%). The indications and therapeutic modalities are described and discussed. The results are compared with the data found in the literature. This is an availability and emergency surgery, the last means to avoid life-saving amputation. The rate of patent revascularization after one year can be as high as 85 to 90%. Almost 9 extremities out of 10 can be saved.

Adult↗
PubMed1992

[Colonic perforation during colonoscopy. 100 cases].

The analysis of 100 cases of colon perforation during colposcopic examinations highly demonstrates such a statement. The perforation risk during colposcopies is generally of the order of 0.2% for a diagnosis coloscopy. According to the statistic data used, it can reach 0.5 to 3% in therapy coloscopy. This is a risk inherent to the technique used. It is thus required to analyse the causes and take the appropriate measures to reduce it to a minimum. Mortality due to such a complication remains high (14%), i.e about 0.015 to 0.1% (#2/10000) of all colposcopies. In 11% of the patients, serious sequelae are to be observed. This demonstrates the significance of the medico-legal problem set by these perforations during colposcopies. The whole personnel responsibility can be involved: colposcopist, surgeon, anesthetist and hospital unit.

Adult↗
PubMed1992

Low protein catabolic rate and serum albumin correlate with increased mortality and abdominal complications in peritoneal dialysis patients.

We retrospectively reviewed 167 consecutive peritoneal dialysis patients with regard to serum albumin (Alb), mortality and abdominal complications. In addition, 25 patients were studied with serial measurements of urea kinetics. The patients were divided into four groups based on their dialysis index (DI) and normalized protein catabolic rate (NPCR) (Table I). 12/167 patients were identified with abdominal catastrophes. Before these complications occurred, the M Alb in this group was 2.67 + 0.24 (compared to age, sex and disease matched controls of 3.55 + .11 P < .05). Six of these patients died from abdominal complications. In the 26 patients with serial urea kinetic studies, 4/11 patients in group IV died (low NPCR and low DI) (P < .05 compared to Group I, II or III). We conclude that urea kinetic modeling is predictive of outcome in those patients with presumed poor nutrition and inadequate dialysis and that abdominal catastrophes are more common in those patients with poor nutrition. Prospective interventional studies should be designed in an attempt to improve the poor outcome in this group of patients.

Humans↗
PubMed1991

Vegetative response during imagined movement is proportional to mental effort.

Measurement of cardiac and respiratory activity during mental simulation of locomotion at increasing speed revealed a covariation of heart rate and pulmonary ventilation with the degree of imagined effort. The degree of vegetative activation of a subject mentally running at 12 km/h was comparable to that of a subject actually walking at 5 km/h. This effect cannot be explained by an increase in peripheral (e.g. muscular) metabolic demands. Indeed, oxygen uptake decreased during motor imagery. This finding is suggestive of a commonality of neural structures responsible for mental imagery of movement and those responsible for programming actual movement. In addition, it provides an quantifiable way of testing mental imagery in relation to movement by using easily accessible biological markers.

Adolescent↗
PubMed1991

[The posterior interparietoperitoneal spaces or retroperitoneal spaces. 1: Normal topographic anatomy].

The posterior spaces between the wall and peritoneum or extraperitoneal spaces are located between the visceral retrocolic and retro-duodenopancreatic fascias anteriorly and the parietalis fascia posteriorly. They were studied using an anatomic and computed tomographic comparison. The propria fascia (lateroconal fascia) divided into the anterior and posterior layers of the perirenal fascia. The fascias delimitate two anterior and posterior pararenal spaces around the kidney compartment and two anterior and posterior perirenal spaces in the compartment itself. These spaces extended above and below the renal compartment from the diaphragm to the pelvis. These large spaces composed of fat and organs can assume the guided migration of pathologic processes or their spread according to the importance of the fascias barriers. They below to the genito-urinary region. The extraperitoneal spaces are related anteriorly to the retroperitoneal alimentary organs: duodenum, pancreas, ascending and descending colon depending of the alimentary region. They are related posteriorly with the abdominal wall and its own fat. The individuality and the interdependance of these three territories (alimentary, genito-urinary and abdominal wall) and their consequences for pathologic CT scan imaging will be discussed in the second part of this paper.

Humans↗
PubMed1991

[The posterior interparieto-peritoneal or retroperitoneal spaces. 2: Pathological x-ray computed tomographic image].

The old reports about the interparieto-peritoneal spaces described particularly the renal space and its environment. The CT scan has modified the in vivo study of the extraperitoneal spaces (E.P.S.) and brought the question of the acquired knowledge up again. An anatomical research was performed in the first part of this study which describes the structures limited between the parietalis fascia and visceral peritoneal fascias. These are the true EPS which the main element is the propria fascia of Sappey (lateroconal fascia) and its anterior and posterior renal double layers. All these lamellar structures limits spaces variably infiltrated with fat tissue: the anterior pararenal space almost virtual, the posterior pararenal space which continues till the Bogros space and the anterior and posterior renal spaces of the renal compartment which the fat continues till the bladder and accompanies the ureter. The second part of this study precises some notions of general topography which are necessary for reading abnormal CT scan images. This part reminds the aortic and arterial general organization of the vertebrates as described by Mackay. It underlines the architectural importance of the three areas so defined: parietal or peripheral, intermediate or mesoblastic genitourinary and deep lateral or digestive endoblastic. These three areas corresponds to the three vascular aortic circles. It emphasized the importance to accept in practice the notion of visceral joining fascia which has been proved in adult people. The longitudinal architecture of the compartments is precise with respect to their appartenance to one among the three arterial arches of Mackay. What the anatomy suggest, the pathology can prove. Several pathological processes are studied on CT scan: large hemorrhagic or necrotic collections in acute pancreatitis, abnormalities or diseases of renal or adrenal compartments, extraperitoneal mesenchymomas, diseases of the psoas compartment. All these observations are analysed in order to explain anatomical and CT scan findings. This study refers not only to the oldest researches which are still valuable but also to the most recent controversies. All the questions are not solved using the clearest schemes.

Abdomen↗
PubMed1990

Arterial vascularization of the operated stomach: highly selective vagotomy, anterior lesser curve seromyotomy, esophageal replacement by transposed stomach after esophagectomy or circular pharyngolaryngectomy.

The rich vascularisation of the stomach is well known and the remarkable tolerance of the organ to vascular ligatures has been emphasised. However, some clinical observations as well as more and more detailed anatomical studies suggest some modification of this classical concept, especially when operating on the viscus. The aim of this work was to evaluate particularly the importance of parietal ischemia which follows hyperselective vagotomy and the more recent anterior seromyotomy, on the one hand, and the gastrolysis that precedes gastro-esophagoplasty after esophagectomy or circular pharyngolaryngectomy on the other hand. The stomachs of 40 unembalmed adult cadavers were studied by angiography in various ways, according to the operation which was being considered. The findings indicated that hyperselective vagotomy caused an avascular band 2 cm wide along that part of the lesser curve affected by the surgical intervention, and that anterior seromyotomy (allowing for some technical artifacts) caused almost no parietal ischemia, and lastly, that the ischemia from gastro-esophagoplasty varied according to the technique used. Useful conclusions, supported by numerous illustrations, will allow the surgeon to define better the vascular requirements when choosing the procedure to be used, taking account of the clinical situation.

Arteries↗
PubMed1989

Lack of correlation between clinic and 24 hour ambulatory blood pressure in subjects participating in a therapeutic drug trial.

Although previous studies document that blood pressure measured in the clinic may differ significantly from blood pressure recorded over 24 hours, the impact of these differences on patient selection for therapeutic drug trials is unknown. A placebo controlled double-blind evaluation of an experimental antihypertensive agent was conducted. Of 30 patients entered, 21 were admitted to the active drug phase of the protocol on the basis of a clinic supine diastolic blood pressure greater than or equal to 95 mmHg; 9 subjects with lower levels of diastolic blood pressure were dropped. Noninvasive ambulatory blood pressure monitoring was performed during the placebo period. Comparison of the two subgroups demonstrated similar levels of 24 hour blood pressure (142 +/- 13/86 +/- 7 vs 137 +/- 10/82 +/- 10). Analysis of individual patient data showed that 24 hour mean diastolic blood pressure was apparently normal (less than or equal to 80 mmHg) in 5/21 (24%) "admitted" and 3/9 (33%) "dropped" subjects. Circadian blood pressure pattern were similar in the two subgroups. A statistically large difference was noted between clinic and 24 hour blood pressures in the "admitted" subgroup (20 +/- 18/13 +/- 7 vs 7 +/- 12/4 +/- 6, p less than 0.08/p less than 0.001), suggesting that patients exhibiting a marked blood pressure rise in the clinic setting were preferentially selected.

Antihypertensive Agents↗
PubMed1989

[The Chinese flap in reconstructing the posterior pharyngolaryngeal wall, mouth cavity and in reoperation after failure of pedicled digestive transfer].

The Chinese flap has already been recommended in the context of circular pharyngolaryngectomy. The authors studied its vascularization from an anatomy-focusing project carried out on 40 dissection cases. They broaden the applications of this material to posterior reconstructive pharyngectomy, for which they specify the methods and routes of access. Other applications are proposed: this flap may represent an alternative for reconstitution of the oral cavity, or even as a second-intent surgical procedure where other technics have failed.

Adult↗
PubMed1987

Tympanic temperatures during hemiface cooling.

In adult men the left half of the head was covered with thick heat insulation, and the right hemiface was cooled by spraying a mist of water, and vigorous fanning. The subjects were immersed up to the waist in warm water (42 degrees) to achieve hyperthermia. In control sessions the subjects were rendered slightly hypothermic by preliminary exposure to cold. Under the hypothermic condition during right skin cooling, the right Tty remained low as compared with oesophageal temperature, while the left Tty was raised. Under the hyperthermic condition right hemiface cooling maintained not only the right Tty lower than oesophageal but also, to a lesser extent the left Tty, while the skin on the left side was close to core temperature. This latter result cannot be explained by conductive cooling from the skin to the tympanic membrane and implies a vascular cooling of the left Tty originating from the other side of the head. It is concluded that selective cooling of the brain takes place during hyperthermia. The main mechanism is forced vascular convection, but conductive cooling also occurs.

Adult↗
PubMed1987

The effect of face fanning during recovery from exercise hyperthermia.

Hyperthermia was induced in nine subjects on two separate occasions by a progressive treadmill run, which resulted in an average esophageal temperature (Tes) of 39.77 +/- 0.07 degree C after 30-57 min. Fanning the face during exercise to simulate conditions during running (wind at 3.75 m X s-1) maintained a tympanic temperature (Tty) that was lower than Tes; the difference was 1.5 degrees C at the end of exercise. In one session, face fanning was interrupted at the end of running, whereas in the other it was maintained for 15 min after exercise stopped. Face fanning had no significant influence on the fall of Tes during recovery, but it markedly influenced the course of Tty during this period. When face fanning was stopped at the end of the run, Tty rose by nearly 0.5 degree C, peaked after 4.5 min, and thereafter decreased slowly to a value close to Tes. In contrast, when face fanning was maintained throughout the recovery period, Tty rose only slightly (0.1 degree C) and remained significantly lower than Tes at all times. The results suggest that following hyperthermic exercise, face fanning could be helpful in preventing acute cerebral hyperthermia.

Adult↗
PubMed1979

[Isolation of the yellow fever virus from an egg-cluster and the larvae of the tick Amblyomma variegatum].

The yellow fever virus is isolated in natura from eggs of a Tick Amblyomma variegatum. It is then isolated from larvae issued from the same egg-cluster and also from blood of a monkey bitten by larvae of the same origin. It is reported that the same virus has been previously obtained from adults of the same species of Tick. An acarine appears for the first time as a sylvatic vector and reservoir (at least temporary) of yellow fever.

Animals↗
PubMed1979

[Effect of commonly practiced manoeuvres in vascular microsurgery. Study under the scanning electron microscope (author's transl)].

The authors studied in 100 Wistar rats the manoeuvres that may commonly be carried out during vascular microanastomosis of diameter less than 3 mm (aorta and posterior vena cava): clamping for 30 to 45 minutes, bipolar electrocoagulation of the collateral arteries, more or less marked pinching of the vascular wall. The risk of thrombosis seems all the greater when: --the surgeon is inexperienced: viz. trauma with the forceps, parietal tears at the level of the stitches, two many threads passed for hemostasis (all these factors accentuate the fibrinoid and platelet deposits); --bipolar electrocoagulation of a collateral artery applied too close to the vessel to be anastomosed (less than 1 mm.)The formation of a smooth and regular fibrinous pseudo-intima appears within 48 to 72 hours which may explain the elective onset of thromboses before this delay.

Animals↗