Biomedical subjects
Publications and source records attributed to M Pascal.
Carnitine acyltransferase of liver mitochondria prepared from obese Zucker rats has a higher sensitivity to inhibition by malonyl-CoA compared with carnitine acyltransferase of mitochondria prepared from lean Zucker rats.
A new immunomodulator, LF 1695, was analyzed in vitro for its capacity to induce T cell markers (HTLA and OKT3, 4 and 8 antigens), to enhance the mitogen-induced lymphocyte proliferation, and to increase the Con A-induced suppressor activity. The inductive activity was compared with that of thymic hormone (thymosin fraction V). LF 1695 was capable of significantly augmenting the percentages of HTLA+ cells (10-15%) and of OKT 3+,T4+, or T8+ cells (13-28%) in human bone marrow prothymocytes. Maximum induction was observed at the concentration of 0.5 microgram/ml. In addition, LF 1695 significantly augmented the proliferation of human peripheral blood lymphocytes stimulated by mitogens (Concanavalin A, phytohemagglutinin, pokeweed mitogen and phorbol myristate acetate). LF 1695 also increased the Con A-induced suppressor activity of human lymphocytes. These data indicate that LF 1695 is active both on T cell precursors and on more mature T cells.
The aim of the authors is to give some precisions about the relationship between the cycle of Echinococcus multilocularis and the dynamics of the different potential hosts (rodents and carnivorous) existing on the area under study (Sept-Fontaines, Doubs, France), by analysing the results of rodents trapping operation (mainly on Microtus arvalis) some of it are infested by the parasite. For this purpose they include the parasite in a prey-predator system and show how the behavioural pattern of the different species involved in the system (in one hand, the predator, Vulves vulpes, infested by the adult form of the parasite, in an another hand the prey, different vole species, infested by larvae) allowed a regular circulation of the parasite between rodents and foxes. In the view of increasing our knowledge about the dynamic of parasite transmission they propose an ecological approach which should allowed to realise a real epidemiological study. In the described process the diversity of habitats had been taken into consideration and play a fundamental part.
The salivary composition and flow rate of 78 patients with primary affective disorders and of 49 healthy volunteers were examined. The former were divided into two groups: Group 1--57 patients receiving lithium carbonate and psychoactive drugs, and Group 2--21 patients receiving psychoactive drugs only. A significant correlation between salivary and serum lithium was found in patients on chronic lithium therapy. Significantly reduced salivary flow rates and elevated potassium, calcium, magnesium and IgA concentrations were found in all the patients as compared with those of the healthy volunteers. Salivary sodium concentrations were significantly elevated in patients on lithium carbonate as compared with the levels in patients on psychoactive drugs only. These results indicate that changes in salivary gland function may occur in patients with primary affective disorders and in those receiving drug treatment. The use of saliva analysis for monitoring lithium dosage is recommended.
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It has been proposed that a platelet-derived growth factor (PDGF) may play an important role in the genesis of atherosclerosis by promoting proliferation of smooth muscle cells. The present study shows evidence that fenofibric acid inhibits the growth promoting activity of PDGF on cultured smooth muscle cells. When smooth muscle cells are in a quiescent state by feeding them a PDGF -and lipoproteins- deficient medium, addition of a platelet extract induces DNA synthesis in a synchronous fashion. A 6 hours' exposure of cells to this extract is sufficient for this effect. Fenofibric acid could inhibit this synthesis when the compound was present in the culture medium concomitantly with platelet extract. This result suggests that fenofibric acid target is a cellular event attendant on PDGF-induced growth promotion. Fenofibric acid is a hypolipidemic drug which inhibits 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (HMGCoA reductase) activity, the limiting step of endogenous cholesterol synthesis. If any endogenous cholesterol is available, smooth muscle cell cholesterol needs for proliferation can be supplied by LDL-cholesterol. As the addition of LDL to the culture medium did not overcome fenofibric acid inhibition, this demonstrates a cholesterol independent mechanism for the anti-PDGF growth promoting activity. The fact that fenofibric acid, a hypolipidemic drug, can also inhibit growth promoting activity of PDGF suggests that this drug can be effective on the prevention of atherosclerosis and cardiovascular diseases by at least two independent mechanisms.
The authors report 19 cases of simple arthrolysis of the proximal interphalangeal joint for flexion rigidity. Their cases were limited to isolated lesions of the joint without any flexor or extensor tendon involvement. The technique is described, and the importance of postoperative physical therapy is stressed. The results in these cases, in contrast with those in complicated cases of rigidity, are very satisfactory. The etiology is primarily sprains and dislocations of the proximal interphalangeal articulation, immobilized for too long a time in flexion (in the so-called "functional position").
The authors used Hunter's technique to treat 16 cases of fixed-flexion deformity of the finger (with irreducible flexion of the joint greater then 70 degrees), secondary to lesions of the flexor tendons. The flexion deformity was corrected in 11 of the 16 cases, and active movement greater than 70 degrees was obtained in only 7 cases. Technical difficulties (particularly cutaneous problems), frequent complications, prolonged reeducation are the reasons that the indications for its use are exceptional, and why there is need for excellent cooperation by the patient.
The structural localization of apo B, the major protidic constitute of low density plasma lipoproteins, was investigated in human dermis using an immunofluorescence procedure and an immunoperoxidase technique. Apo B was found attached to plasmic fibroblast membranes and along collagen fibers. Dermal areas containing apo B were more numerous in patients with coronary disease than in subjects of the same age with healthy coronary vessels. These results are consistent with those of biochemical determinations: concentrations of apo B in the aorta and skin are parallel and vary according to the severity of atheromatous lesions.
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The implication of HDL as a negative risk factor in cardiovascular disease has focused on the need for an accurate but rapid routine method for determining HDL-cholesterol in human serum. A practical approach is the specific precipitation of apo-B-containing lipoproteins (atherogenic lipoproteins) by Concanavalin A (Con. A), a lectin with high affinity for glycoprotein apo-B. Specificity was assessed by radial immunodiffusion of apoprotein B in whole serum and in Con. A supernates. Double-immunodiffusion of isolated LP-fractions against anti-apo-B and Con. A demonstrated immunochemical identity of Con. A precipitable LP with apo-B-containing LP. Con. A precipitated cholesterol in the d : 1.063-1.21 g/ml fraction when apo-B was present. Complete precipitation of low density cholesterol was demonstrated, using a reconstituted serum sample radiolabelled in the d less than 1.063 g/ml fraction. Treatment of a reconstituted serum sample containing radiolabelled 125I-apo-A-I with Con. A demonstrated precipitation of trace amounts only of apo A-I. Con. A precipitated LP-B cholesterol quantitatively even when serum triglycerides (TG) exceeded 37.7 mmol/l. Clinical application of this method revealed that 73% of the patient population demonstrated apo-B in the d greater than 1.063 g/ml fraction.
DNA polymerase-alpha from the cytosol of regenerating rat liver has been highly purified by a procedure which includes affinity chromatography. The purified enzyme sediments at 7.4 S in high ionic strength and at 9--10 S in low ionic strength, i.e. under in vitro polymerization conditions. This enzyme has all the properties of the other mammalian DNA polymerases-alpha: sensitivity to sulfhydryl-blocking agents, to heparin, and to the level of salt in the assay, neutral pH optimum, use of ribonucleotide-initiated DNA templates, and inability to copy the ribostrand of hybrids. After chromatography on denatured DNA-cellulose, the alpha-polymerase is completely devoid of exo- and endonuclease activities. Template competition experiments indicate that the binding of the enzyme to the template can be distinguished from the polymerization itself and that the in vitro synthesis catalyzed by this alpha-polymerase is not distributive in a classical sense. These facts are discussed.
The interaction between the nicotinamide adenine dinucleotide binding domain of calf spleen NAD glycohydrolase and its ligands has been studied. The use of competitive inhibitors, structurally related to different portions of the NAD molecule (i.e. adenosine and nicotinamide moieties), revealed the considerable importance of the binding between the pyrophosphate linkage and probably an arginyl residue of the active site. This interaction allows the positioning of the substrate in a conformation which permits catalysis to occur. The binding between the 2'-hydroxyl of the adenosine moiety and a residue of the active site, which exists in NAD-linked dehydrogenases, is probably missing in the calf spleen NAD glycohydrolase, based on the inhibition by salicylates, 2'-deoxyadenosine 5'-monophosphate and the hydrolysis of the 2'-deoxyadenosine analogue of NAD. The NAD glycohydrolase could be completely inactivated by 2,3-butanedione, an arginyl-modifying reagent. The reaction followed pseudo-first-order kinetics and the modification was found to be reversible. Woodward's reagent K, a reagent for carboxyl residues, partially inactivated the enzyme, which resulted in a change of the NAD glycohydrolase kinetic parameters Km and V. The inactivation rate was complicated by a parallel decomposition of the reagent.
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Glycogen reserves are entirely consumed during total starvation of Bombyx mori L. larvae. While the storage of glycogen is lowering and the dietary supply of carbohydrates stopped, the amount of trehalose also decreases but less rapidly than this of glycogen. Relative homeostasis is maintained but only for the ten first hours of inanition. Quantitative evaluation of blood trehalose, which is preformed more rapidly than glycogen analysis, might be used as an efficient test to characterized some physiopathological states.
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