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Biomedical subjects

A Geyssant

Publications and source records attributed to A Geyssant.

At least 73 records · Page 4Linked to original sources
PubMed1987

Hemoglobin Grange-Blanche [beta 27(B9) Ala----Val], a new variant with normal expression and increased affinity for oxygen.

Hemoglobin Grange-Blanche [beta 27(B9) Ala----Val] is a new variant found in a Portuguese family. The carriers present moderate erythrocytosis. Upon isoelectric focusing, Hb Grange-Blanche was slightly more cathodic than Hb A. beta Grange-Blanche chain migrated like the G gamma chain when submitted to electrophoresis in the presence of urea-Triton X-100. The precentage of Hb Grange-Blanche was about 50% in the heterozygous state. Oxygen affinity was increased (P50 = 22 mmHg), but heme-heme interaction was normal. An abnormal tryptic peptide (beta T3) was isolated using HPLC. Its composition allowed us to deduce unambiguously the amino acid change. The latter is the third mutation found in position 27 of the beta-chain. Because of its normal expression and its elevated affinity for oxygen, Hb Grange-Blanche contrasts with Hb Knossos [beta 27(B9) Ala----Ser], a beta-thalassemic variant with low affinity.

Adult↗
PubMed1986

Effects of endurance training on capillary supply of human skeletal muscle on two age groups (20 and 60 years).

Two groups of human subjects were submitted to a 20-week endurance training program (1 h a day, 4 days a week, 70-80% max VO2). The first group (G20) consisted of eight 22 +/- 3 years male students, the second group (G60) was composed of seven still very physically active elderly male subjects (62 +/- 4 years). Training significantly increased max VO2 by 15% in G20 and 7% in G60. Muscle samples taken from the vastus lateralis muscle before and after training were histochemically stained for fibre-typing (myofibrillar ATPase), capillary supply and fibre area measurements (amylase PAS and NADH-TR). Fibre-type distribution was unchanged with training. Capillary density (cap X mm-2) increased significantly in both groups from 316 +/- 42 to 396 +/- 73 in G20 and from 308 +/- 48 to 409 +/- 55 in G60. This enhancement of capillary supply was linked to the proliferation of capillaries in G20 where the number of capillaries in contact with ST and FTa fibres (CC) significantly increased from 4.6 to 5.9 and from 4.8 to 6.1 respectively. No significant changes in fibre areas were found in G20. On the contrary, G60 did not show any significant sign of capillary growth (CC unchanged) whereas fibre areas significantly decreased in ST (6,410 to 5,520 micron 2) and FTa fibres (5,830 to 5,090 micron 2). A methodological evaluation of fibre-area measurement was described, with confirmation of the data. It was concluded that this study may illustrate the trainability of skeletal muscle of elderly men in a possibly different way to that seen in a younger age group.

Adult↗
PubMed1985

Lactate determination with the lactate analyser LA 640: a critical study.

Using the new method of sample preparation developed by the manufacturer in 1979, the lactate analyser LA 640 now provides reliable measurements of blood lactic acid from blood micro-samples of 20 microliters within 2 min. Reproducibility is comparable to that obtained by spectrophotometric assay with +/- 0.2 mmol . l-1 for 95% confidence limits. High accuracy was also obtained with 95% linked confidence limits within +/- 0.19 mmol . l-1 and +/- 0.46 mmol . l-1 for blood lactate concentrations of from 2-4 and 7-9 mmol . l-1 respectively. Due to a lactate concentration increase of 0.5 mmol . l-1 . h-1 in whole blood kept at 20 degrees C, the blood must be immediately diluted in the buffer haemolysing solution after withdrawal. This diluted sample can then be stored at room temperature without alteration, provided the concentration in the dilution is lower than 0.8 mmol . l-1. For serial successive measurements, a new sample can be tested before the electrode current reaches its background value.

Blood Chemical Analysis↗
PubMed1985

[Use of the LA 640 for a simple method of measuring the concentration of muscle lactate].

A simple technique was elaborated for the measurement of muscle lactate concentration. It was tested on samples of muscle vastus lateralis taken by the Bergström (1962) needle biopsy technique at the end of 20 min exercise bouts corresponding to 60-70% of Vo2 max. The biopsies were freshly frozen in liquid nitrogen, powdered and weighed in a cryostat at -20 degrees C. The extraction were made by saponine and the lactate measured in the saponine solution by an electrochemical-enzymatic method (LA 640). The results concern: the time of taking the biopsies and the freezing time (27 +/- 11 s and 34 +/- 9 s respectively); the accuracy of weighing (inducing a 1% uncertainty in the final result); a comparison of the saponine extraction with the perchloric acid extraction and a checking of the extraction capacity of the former; the accuracy of the whole measurement (the mean relative confidence limits are +/- 8-10%; the reproducibility of the technique through measurement of the variation coefficient (18%) calculated on measurements performed at a 15 days interval in 6 trained subjects. The discussion of the results and their comparison with those of the literature lead to the conclusion that the described method is suitable for muscle lactate measurements.

Animals↗
PubMed1984

[Maximal effort, maximal heart rate and serum lactic acid in exercise electrocardiography. A comparative study].

In exercise stress testing the quantification of effort on which the value and significance of the test depend is based on two simple and practical criteria: theoretical maximal heart rate for age (MHR) and serum lactic acid levels 3 minutes after exercise. Usually only MHR is used, 85% of MHR being the common cut-off point between "interpretable" maximal or "inframaximal" effort and useless effort. Our study was based on 1 000 exercise stress tests performed over a two year period with the same protocol and equipment. Initially, we determined our values of MHR and serum lactic acid in undoubted maximal effort stress tests, as shown by a levelling out of the heart rate during the last load increments, the last stage of exercise being sustained for at least 1.5 minute. The application of both criteria to all the investigations showed significant differences in the evaluation of the exercise obtained when the maximal measured heart rate was between 85 and 95% of MHR. This was also true, to a lesser extent, in patients over 60 years of age or under 30 years of age with maximal measured heart rate of 85% or less than MHR. A discussion of the theoretical basis of the two criteria helps explain this divergence, attributing it to the inaccuracy and unreliability of the MHR. The only obstacle to the use of serum lactate as the preferential indicator of maximal effort is the need for laboratory facilities and the delay in obtaining the result.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

[Methemoglobinemia in acute diarrhea in infants].

8 cases of methemoglobinemia are observed in infants of 28 days to 138 days of age, who have all acute diarrhea. They are divided in two groups. --4 infants who have eaten for a long time a rich nitrate and nitrite content carrot soup. --4 cases of severe diarrhea with probable endogenous nitrification due to microbial proliferation. The methemoglobinemia level is here not very high and represents more a witness that an alarming symptom. Those infants are compared with 10 infants who have diarrhea without methemoglobinemia. Symptoms and treatment of methemoglobinemia are revisited.

Acute Disease↗
PubMed1982

Effect of 40 weeks of endurance training on the anaerobic threshold.

The effect of a 40-week training program on the anaerobic threshold (AT) was studied in five subjects (35 +/- 5 yrs). The training program consisted of a bicycle ergometer exercise 1 h per day 3 days a week at a work load corresponding to 80%-85% of VO2 max. Before training (S0) and at the 10th, 20th, 30th, 40th weeks (S10, S20, S30, S40) of the training program, ventilatory AT (AT vent), lactate AT (AT lact), and 4 mmol AT were estimated using a graded exercise test. In the same period, another test (1) to determine VO2 max, maximal work load (MWL), and net efficiency (2) and a 1-h endurance exercise requiring 85%-90% of VO2 max were performed. After training, AT increased significantly by 10%, 11%, and 18% in AT vent, AT lact, and AT 4 mmol, respectively. MWL and net efficiency increased by 22% and 14% respectively, and there was no significant increase in VO2 max. The AT increase at S20 was delayed as compared to the change in MWL (S10). It is hypothesized that an AT increase provides good evidence for modifications of the muscular oxidative capacities during an endurance training program. A part of this paper is devoted to (1) the study of the reproducibility of AT estimation, (2) a comparison to other methods for determining the definition of AT, and (3) the correlations between the three methods utilized for AT estimation.

Adult↗
PubMed1981

Plasma vasopressin, renin activity, and aldosterone: effect of exercise and training.

The influence of endurance-training on hematocrit, plasma vasopressin, renin activity, and aldosterone changes at rest and at the end of an exercise performed until exhaustion at a given and constant relative work-load (87% of maximal oxygen uptake) has been studied in four untrained subjects submitted to a 5-month training. At the end of this period, maximal oxygen uptake increased of 15.2% (p less than 0.01). Hematocrit at rest slightly rose after training, and if exercise constantly induced increases in hematocrit before (p less than 0.001) and after training (p less than 0.005), the per cent increase after training was lower than before (p less than 0.05). Comparison between the importance of weight loss and hematocrit variation showed that when untrained subjects become trained the variation of hematocrit after exercise becomes smaller while weight loss is more important (p less than 0.01). Plasma renin activity (PRA), aldosterone (Aldo) and vasopressin (AVP) levels, compared to control values, displayed a significant increase after exercise before as well as after training. Control values remained unchanged after training for aldosterone and AVP, but were significantly lower (p less than 0.05) for PRA. This latter observation could be explained by the change in blood volume induced by exercise.

Adult↗
PubMed1981

RBC filterability, oxygen saturation, ATP intracellular stock, and cerebral microcirculation.

The filterability of erythrocytes through Nucleopore filters of 5 micrometer has been studied with a new device (Hemorheometer SPO1). A reliable and reproducible index of filterability (IF) can be obtained which depends only on the red blood cell deformability. The results showed an alteration of red blood cell deformability in some pathological circumstances like smoking and that deformability depends on the nature of haemoglobin, the ATP intracellar stock and the saturation of haemoglobin by oxygen. The cerebral microcirculatory consequences of alterations of red blood cell deformability has been studied in vitro by measuring whole blood filterability on 5 micrometer Nucleopore filters with the classical technic of Reid & Dormandy and in vivo by 99mTc cineangioscintigraphy and by determination of the regional cerebral blood flow by the 133Xenon inhalation technic. The results showed an increase of cerebral ascensional time and mean transit time of the cineangioscintigraphy and a decrease of regional cerebral blood flow in patients presenting with a decrease of whole blood filterability flow.

Adenosine Triphosphate↗
PubMed1981

[Plasma renin activity (PRA) and aldosterone (PA) during submaximal exercise. Effect of training (author's transl)].

The effect of training on PRA, PA, hematocrit and weight loss was studied at rest and following an exercise performed until exhaustion. Two groups of subjects were used, the first, a group of 4 young well trained men (88.6% +/- 7.7 V02 max) and the second a group of 4 young untrained men (77.5% +/- 7 V02 max). PRA and PA displayed highly significant increases after exercise in both groups, but PRA resting values were lower in the well trained subjects (p less than 0.05). PRA values were also lower in the latter group after exercise, but the difference in this case was not significant. Further, the variation of hematocrit was less (p less than 0.05) and the weight loss greater in the well trained subjects. In an additional experiment, the same parameters were studied in four subjects submitted to a five month training programme (87% V02 max). Though resting values for PA remained unchanged after training, PRA resting values and PRA post exercise values were significantly lower. A comparison between the magnitude of weight loss and hematocrit variation showed that when untrained subjects became trained, the variation of hematocrit was smaller (p less than 0.05) while weight loss was larger (p less than 0.01). These observations could be explained in terms of the change in blood volume, and/or a decrease in sympathetic nervous activity induced by training.

Adult↗
PubMed1977

[Changes in the affinity of oxygen for hemoglobin during general anesthesia].

The well known effects of the lowering of the intraerythrocyte 2, 3, diphosphoglycerate (2, 3, DPG) level and hypothermia, on the affinity of oxygen for hemoglobin, lead the authors to study the influence of these parameters on this affinity during general anesthesia. The following observations were made in 15 adult subjects, undergoing prolonged general anaesthesia (average time: 3 hrs. 10 minutes): the dissociation curve of oxyhemoglobin (DCO) by the method of mixing, the intraerythrocyte 2,3, DPG level, the hemoglobin concentration and arterial blood parameters (PO2, PCO2, pH). These measurements were recorded before and after the general anaesthesia. The results were the following: a significant reduction of P50, measured under standard conditions (from 27.64 +/- 1.74 torr to 25.57 +/- 2.28, p less than or equal to 0.01) associated with a decrease in 2,3, DPG (from 0.94 +/- 0.31 mol/mol Hb at 0.64 +/- 0.24 p less than 0.01). Among the factors responsible for this variation in the affinity, it was proved that the volume of blood transfused was of importance as well as a decrease in body temperature during the operation. When the temperature is made to vary from 37 degrees C to 35 degrees C. the P50 ranges from 25.57 +/- 2.28 to 22.86 +/- 0.97 (p less than 0.01). To conclude the authors underline the importance of hypothermia and the volume of blood transfused (average time of preservation = 15 days) on the effects of the affinity of oxygen for hemoglobin.

Adult↗