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Biomedical subjects

A Larcan

Publications and source records attributed to A Larcan.

At least 109 records · Page 6Linked to original sources
PubMed1982

[Physiopathology and treatment of vascular spasms].

Vasomotricity and tonus of arterial and arteriolar vessels yield to nervous regulation (central and peripheral, hormonal, metabolic) as well as to local myogenic regulation. The main mediators of vasomotricity are catecholamines which, by their alpha and beta effects, have an effect on the second mediator (3'5' AMP) and on calcic exchanges, angiotension, serotonin and prostaglandins which "modulate" vasomotor reactions. Metabolic factors: pH, PO2, PCO2 and electrolytes balance: Na, K, Mg, Ca have to be considered. The role of the metabolism of the wall and the role of red blood corpuscles (ADP) and of platelets (released substances of granules) have to be mentioned. The physiopathology of spasm must take into account topographic variations. One can distinguish spasms by nervous regulation, by catecholamines discharge and by extreme and lasting muscular contraction. Medicines of the spasm can have an effect on the peripheral sympathetic nervous system, catecholamines, the 3'5' AMP and especially on the smooth muscular fibre, more accessorily on red blood corpuscles, platelets and coagulation. Na nitroprussiate and calcium chelating agents are the most active substances to-day.

Animals↗
PubMed1982

[Climatologic parameters and risk of acute vascular, neurologic and cardiac incidents].

In order to discover a possible correlation between climatic parameters and the occurrence of acute neurological vascular accidents (thrombosis, hemorrhages) and of cardiac accidents (myocardial infarction), the data of a meteorological card-index including climatological parameters [atmospheric pressure in millibars, temperature of the air under shelter in degrees Celsius, relative humidity, speed and direction of the winds, hydrometeors and electrometeors) as well as parameters of solar and ionospheric activity (daily flare index (DFI), index of the geomagnetic activity (AA), daily planetary index (AP), phases of the moon] were compared. The study concerned a period of 731 days and the parameters, subdivided into classes and gradients, were compared with the admission to hospital of 535 patients with myocardial infarction and of 378 patients with stroke. The statistical study consisted in searching for correlations between the parameters considered two by two and in applying the method of the factorial analysis of correspondence for a more extensive analysis. The frequency of the vascular accidents increased when the temperature of the air was less than 12 degrees, when there was hoar-frost with fog, rain or snow and when the DFI was less than 530. The factorial analysis of correspondence enabled to consider 3 fields in which correlations were suggestive for 3 distinct affections: myocardial infarction, cerebral hemorrhages and cerebral thrombo-embolisms.

Cerebrovascular Disorders↗
PubMed1981

[Blood viscosity. Measurement and applications (hyper--and hypoviscosity syndromes) (author's transl)].

Blood has particular rheological properties which partly condition its flow, especially in capillary vessels, and its ability to deliver oxygen. It is not subject to gravitation, pseudoplastic, thixotropic and visco-elastic. Blood viscosity depends upon macroscopic factors, such as erythrocyte aggregation and deformability. Hyperviscosity is observed in cases of increased haematocrit (polycythaemia and relative polycythaemia), increased serum proteins and changes in protein balance (e.g. rise in fibrinogen and immunoglobulins, fall in albumin) as seen in inflammation and dysglobulinaemia, drop in temperature (hypothermia), increased erythrocyte aggregation (shock, fat embolism) or imparied deformability due to various acquired or inherited disorders of red cell membrane or cytoplasma (e.g. sickle cell anaemia, renal failure, hyperlipoproteinaemias, thrombosis, diabetes). The various factors may be combined, as in diabetes. Conversely, hypoviscosity may result from decreased haematocrite, fall in blood proteins and fibrinogen, or hyperthermia. Hyperviscosity can be corrected by acting on its various constituents. Treatments include haemodilution, plasmapheresis, anti-aggregants and drugs improving red cell deformability.

Blood Proteins↗
PubMed1981

Deformation and orientation of red blood cells in a simple shear flow. Theoretical study and approach at small angle light scattering.

On the basis of a simple theoretical model representing the rheological behaviour of the erythrocyte membrane, the authors have proceeded with a theoretical and experimental investigation on the light-scattering diagrams at small angles of normal red blood cells subjected to Couette flow. The results show that the light-scattering diagrams take into account not only cell deformation, but also cell orientation. The prospects for applying this method to the analytical separation of cells with different deformabilities are considered.

Biophysical Phenomena↗
PubMed1981

[Air embolus after Caesarean section (author's transl)].

This is case history of a primigravid woman on whom Caesarean section was carried out in normal conditions for fetal distress, the patient being placed in Trendelenburg position. After the abdomen had been closed there was a sudden collapse with cyanosis, right bundle branch block and then coma with hypertonicity, hyperreflexia and transitory hemiplegia. The only possible diagnosis that could be made was of air embolus following Caesarean section in the light of many investigations that were carried out and the improvement under hyperbaric oxygen treatment and the very irregular progress of the neurological symptoms. Published case histories are rare [12] (published by Walrop, 1953 and Nelson 1960) and over all the result has been unfavourable. The diagnosis can be proven when gas has been found in the blood vessels at autopsy or by the finding of certain clinical signs which indicate the presence of air in the heart or in the blood vessels (water mill sound and the sound of air in the blood vessels). Diagnosis is made by exclusion. The differential diagnosis must be made with amniotic fluid embolus and the other cerebro-vascular accidents, as well as obstetrical shock. The principal factors that bring about air embolus are the entry of air into the dilated uterine veins which is helped by the negative pressure achieved by the Trendelenburg position. As soon as this diagnosis is made it is important to start hyperbaric oxygen treatment and symptomatic resuscitation.

Adult↗
PubMed1980

Recurring thrombo-embolic accidents caused by family-related deficiency of the fibrinolysis system.

Several members of the same family underwent examinations on the coagulation and fibrinolysis systems after recurring thrombo-embolic disease was observed in one of the members of the family. The results of biological examinations revealed normal coagulation factors, but a high level of plasminogen activation inhibitors accompanied by an increase in platelet aggregation was observed. These results are compared with the few similar cases reported by other authors. The exact part played in this particular case by the platelets and the inhibitor in the patient's predisposition to venous thrombosis and the spread of the disease is discussed. It would seem that the platelet abnormality merely accompanys the increase in inhibitors which is passed on by recessive autosomal transmission. The authors consider that in all cases of thrombosis, particularly recurring thrombosis, an investigation, comprising a study of the fibrinolysis factors and particularly the inhibitors, must be carried out on the patient's close family.

Adult↗
PubMed1980

[Influence of microaggregate transfusion filters on the rheological properties of blood].

Micro-aggregate transfusion filters have been suggested in order to prevent pulmonary complications in cases of shock after massive transfusions and cerebral complications after ECC. It is important to have prior knowledge of performance, in particular with regard to perfusion flow rate and the efficacy of filtration. Eight filters have been thoroughly studied: Bentley PF 127, Bentley PFF 100, Biotest, Fenwal 4C2417, Fenwal 4C 2423, Intersept, X Pall Ultipor SQ 40 S, Swank IL 40 S. For each of them, study included the following: perfusion flow rate, filtration pressure (Swank technique) of whole blood distal or proximal to the filter, viscosity and various haematological parameters (CBC, free haemoglobin, red cell ATP). Finally, the deposit retained by the filter must be studied morphologically by sweep electron microscopy. It would seem that good aggregate elimination power (decrease in filtration pressure of 75 to 95 per 100) often coincides with a poor flow rate and the need to rapidly change the filter. Efficacy is virtually the same for all filters with the exception of Pall filter where it seems to be less. The Bentley PF 100 and Fenwal 4C 2423 filters combine this efficacy with an adequate flow rate, resulting in easy use in practice. By contrast, the Pall filter with a very satisfactory flow rate is less effective than the other with regard to the retention of aggregates. Other parameters are only very slightly modified by filtration. The deposit collected on the filters consists of fibrinogen, deformed red cells (echniocytes), leucocytes and platelets.

Blood Transfusion↗
PubMed1980

[Modifications in hemorheological parameters following acute medical emergencies (author's transl)].

Various hemorheological parameters were studied in venous blood samples taken during the initial stages of acute medical emergencies in patients admitted to the Intensive Care Unit. These included more particularly: cerebrovascular accidents, recent acute arterial or venous thrombosis, pulmonary embolism, acute renal failure, pregnancy toxemia and emergencies occurring during pregnancy or in the puerperium, coagulation disorders, gas embolism... The examinations conducted were:--measurement of apparent--blood viscosity (eta a) and plasma viscosity--platelet aggregate fixation after fixing in formalin according to the method described by Wu and Hoak--blood filterability through filters with pores 5 microns in diameter. The principal modifications observed, often correlated were raised blood and plasma viscosity, reduction in the aggregation index, and diminution in filterability. It should be noted that the increase in viscosity, constant in all groups, is significant at low shearing speeds in the thrombosis cases, and that this significance is present in nearly all the pathological groups with high shearing speeds. Variations in the aggregation index are very dispersed and of low significance.

Blood Viscosity↗
PubMed1980

[Ergotism of therapeutic origin. A report of 4 new cases (author's transl)].

The observations concern ischemic accidents with various localizations (lower limbs, tongue, uterus, intestine, heart, liver) corresponding to 4 observations for which ergot derivatives (ergotamine tartrate) can be responsible. The most typical accidents are localized at the level of limbs and especially of lower limbs. In the greatest part of observations, a specific terrain (puerperium, vasomotor disorders, suspicion of temporal arteritis) can be considered and favouring factors (infection, and especially associated medicinal treatments with triacetyloleandomycin [2 observations] and Doxycyclin [1 observation]). The posologies of ergot alcaloïds were either superior to the limit prescription or normal. The duration of prescription was variable, but generally short. The arteriography confirms a vascular spasm. In an observation with very severe evolution, various ischemic localizations inducing amputation, two intestinal resections and an hemodialysis for lactic acidosis were noted. These ischemic accidents have to be noticed as early as possible in order to start a treatment; the best one seems to be the association of sodium nitroprussiate in intravenous perfusion with peri-dural anesthesia in an antalgic aim.

Adolescent↗
PubMed1979

[Light and electron microscopic study of hepatic lesions in the course of hyperlactatemia in diabetic patients (author's transl)].

Histopathological study of the liver has been undertaken on twenty-one diabetics with hyperlactatemia exceeding 5 mEq/1 of whom seven were treated with phenformin, six with metformin and eight not biguanide-treated. Hyperlactatemia occurred during the course or during resolution of severe ketoacidosis or of hyperosmolar coma. Hepatic lesions were invariably present. By light microscopy, massive steatosis, steatonecrosis or necrosis of variable extent were observed. Ultrastructural study showed constant mitochondrial abnormalities. These results support the hypothesis of a major role for mitochondrial changes in hepatic cells in provoking pathological hyperlactatemia. In diabetic patients, these mitochondrial lesions could be induced either by an anoxic process resulting from a variety of metabolic insults or by some as yet undefined toxic action of biguanides or by the combination of both of these factors.

Adult↗