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Biomedical subjects

F Schapira

Publications and source records attributed to F Schapira.

At least 37 records · Page 2Linked to original sources
PubMed1978

Location of adult and fetal aldolases A, B, and C by immunoperoxidase technique in LF fast-growing rat hepatomas.

The resurgence of aldolase isozymes in cancerous tissues is a well-known but poorly understood phenomenon. This resurgence poses the problem of whether or not adult and fetal aldolase isozymes are produced by the same cells. For clarification of this question, the immunoperoxidase technique was used to locate aldolases A, B, and C in one type of fast-growing hepatoma, the LF hepatoma and, by comparison, in normal adult liver. Under optical microscopy, aldolases A and C were located in the cytoplasm of almost all of the cancerous cells. An isozyme antigenically identical with aldolase B was also demonstrated to be present in almost all of the cells, but the reaction indicating the presence of this isozyme was weaker. In normal adult liver, only aldolases A and B were demonstrated to be present in almost all the hepatocytes. Under electron microscopy in LF hepatoma, the three isozymes were found to be present mainly in the cytoplasm. These facts suggest that the three types of aldolase are very probably present in the same cells at the same time, and they provide indirect arguments leading us to think that the resurgence of fetal aldolase isozymes in cancer is not the consequence of cellular selection but is due to a disturbance at the gene control level.

Animals↗
PubMed1978

Prenatal diagnosis of galactosemia.

We have monitored 3 pregnancies at risk for galactosemia by deficiency in Galactose-1-Phospho uridyl transferase. Galactosemia was diagnosed in the 1st case; heterozygoty in the 2nd, and a "double heterozygoty" in the 3rd. The latter is the first example of such a diagnosis. Post natal confirmation was obtained in the three cases. Arguments are given for the usefulness of this prenatal diagnosis.

Amniocentesis↗
PubMed1977

Isoelectrofocusing of aldolase B from normal human livers and from livers with hereditary fructose intolerance.

By isoelectrofocusing in thin-layer acrylamide-ampholine gel, normal human aldolase B has been resolved into 5 bands. Moreover we were able to specifically stain (after isoelectrofocusing) the mutated aldolase B in livers with hereditary fructose intolerance, and to show that only the 3 most anodic bands are seen. Some different hypotheses are discussed to account for the microheterogeneity of the normal aldolase B, and for the different isoelectrofocusing pattern found in livers with hereditary fructose intolerance.

Carbohydrate Metabolism, Inborn Errors↗
PubMed1977

Purification of aldolase C from rat brain and hepatoma.

An isolation procedure for rat brain aldolase C has been developed which also permits the isolation of aldolase C from experimental hepatomas. Certain enzymatic properties (specific activity and Michaelis constant towards the two specific substrates: fructose 1,6-biphosphate and fructose 1-phosphate) and physico-chemical properties (molecular weight, N-terminal amino-acid) of the two enzymes have been studied and compared. Moreover, an amino-acid analysis has been carried out for rat brain aldolase C. Within experimental errors, the two enzymes appear to be identical.

Amino Acids↗
PubMed1977

Differentiation in vivo and in vitro of pyruvate kinase isozymes in rat muscle.

The M type isozymes of Pyruvate-kinase have been studied by isoelectrofocusing in thin layer acrylamide ampholine gel, during the ontogeny of rat muscle in vivo and during the differentiation in vitro of myoblasts of a line established by Yaffe. In both cases, multiple subbands have been seen; the most acid (pHi 5.2) was the predominant band in myoblasts and in fetal muscle at the 15th day. Several more cathodic bands appear sequentially in vitro as in vivo, one of them corresponding to the "M2" or "K" band (predominant in kidney). The most cathodic band M1 (pHi 7.3), characteristic of the adult muscle, appears at the 9th day of culture in vitro in multinucleated myotubes and at the 20th day of fetal life in vivo. Kinetic results confirm these electrofocusing results, showing in fetal muscle and in myoblasts a sigmoid saturation curve of pyruvate kinase activity with phosphoenolpyruvate as substrate. This allosteric kinetic is progressively replaced by a Michaëlian kinetics in vitro as in vivo. Consequently, the studies in vitro may serve as a model for myogenesis in vivo, and may contribute to the understanding of the significance of the multiple forms of pyruvate-kinase during this myogenesis.

Aging↗
PubMed1977

Possible molecular mechanisms of ageing.

While the error theory of ageing has attracted most interest in recent times it cannot yet be regarded as being demonstrated. Posttranslational modifications of proteins genetic theory appears loical but has little in vivo evidence to prove it. Basic mechanisms of ageing probably involve the interaction of several processes.

Aging↗
PubMed1977

[Human myopathy and animal muscular dystrophy].

Two hereditary muscular dystrophies similar to human progressive muscular dystrophy (P.M.D. Duchenne type) have been isolated in animals, one in mouse, the other in chicken. The decrease in the activity of glycogenolytic enzymes is similar to that observed in denervated muscle. Isozymic fetal types for several muscular enzymes have been observed as well in chicken as in man, but this fetal type may also be found in neurogenic atrophy. The release in circulation of muscle enzymes seems more specific. But the origin of the genetic lesion is still unknown. We describe here the three different theories about this problem: i.e. neurogenic, vascular, or myogenic. This last theory implies a trouble of membrane permeability.

Adenosine Triphosphate↗
PubMed1976

Aldolase B in the liver of senescent rats.

The process of enzymatic aging was studied in livers of adult and senescent rats for aldolase B. No "cross-reacting material" was found in livers of 27 to 30-month-old rats, estimated by the ratio aldolase activity-antigen amount. The activity towards the two substrates of aldolase, fructose 1,6-diphosphate and fructose 1-phosphate did not vary in senescent animals. Moreover, other physico-chemical properties of the enzyme such as thermal inactivation, immunological reactivity and Michaelis constant remain unchanged. These results provide arguments against the occurrence of errors in protein synthesis as a cause of aging.

Aging↗
PubMed1976

Aging and accuracy of protein synthesis in man: search for inactive enzymatic cross-reacting material in granulocytes of aged people.

Enzyme activities and immunological reactivities of seven different enzymes have been assayed in the polymorphonuclear leukocytes from 10 newborns, 10 aged (over 80 years old) and 10 young adults (20-30 years old). Polymorphonuclears have been chosen because both in the newborns, and in the aged people, they are young cells whose life span is a few hours only. Five cytoplasmic enzymes have been immunologically studied by means of monospecific antienzyme sera: leukocyte pyruvate kinase by immunoinactivation, glucose-6-phosphate dehydrogenase and glucose phosphate-isomerase by electroimmunodiffusion, lactic dehydrogenase (muscle-type) by radial immunodiffusion. Two lysosomal enzymes (alpha-mannosidase and beta-glycuronidase) have been titrated immunologically with the same polyvalent antihuman leukocyte rabbit serum. Small but significant differences in activity were observed for several of the enzymes. By contrast, no significant difference was found, for any of the seven enzymes, as regards the ratio enzyme activity/immunological reactivity, between newborns, young adults and aged people. These results of not support the theory that a decreased accuracy of the protein synthesis machinery is responsible for aging and death. By contrast, the authors emphasize that the enzyme abnormalities reported by various authors in old animals or in old fibroblast cultures closely resemble those demonstrated to be "post-translational modifications" in the case of human glucose-6-phosphate dehydrogenase.

Adult↗
PubMed1976

[Cataract due to galactokinase deficiency in a premature infant].

Report of a case of galactosemia due to galactokinase deficiency. The author recalls the clinical (opacity of the lens) and biological features (important galactosuria, gallactiloluria, normal aminoaciduria, minimal hyperglycemia following galactose load). Since symptoms of increased intracranial pressure were present in this case, as in another one previously described, the commonly accepted statement that cataract is the only lesion in galactokinase deficiency must be reconsidered.

Cataract↗
PubMed1975

Resurgence of two fetal aldolases in rat duodenal adenocarcinomas.

We have shown, by kinetic, electrophoretical and immunological methods, the resurgence of two intestine fetal aldolases (A and C) in well-differentiated rat duodenal adenocarcinomas. Our findings demonstrate that the resurgence of fetal isozymes in cancer is a general phenomenon, occurring in intestine, as in liver and other tissues.

Adenocarcinoma↗