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M Zatz

Publications and source records attributed to M Zatz.

At least 235 records · Page 13Linked to original sources
PubMed1980

The use of concomitant serum pyruvate-kinase (PK) and creatine-phosphokinase (CPK) for carrier detection in Duchenne's muscular dystrophy through discriminant analysis.

Serum pyruvate-kinase (PK) and creatine-phosphokinase (CPK) determinations have been carried out in a sample of 30 obligate carriers for the DMD gene and 50 normal adult control females. In all the subjects under study blood samples have been collected 3 times on 3 independent occasions and the means of these 3 determinations were considered for both CPK and PK activities in the statistical analysis. Discriminant analysis has shown that in the group of 30 obligate carriers the estimated proportions of misclassification using either serum CPK, PK or both enzymes were fourn to be: 10/30 (33.3%) for CPK alone, 6/30 (20%) for PK alone and 5/30 (16.6%) for both enzymes. It is concluded that although a small proportion of carriers still remain undetected the concomitant use of PK and CPK determinations enhances the capability of detecting carriers for the Duchenne gene mainly when compared with CPK alone.

Clinical Enzyme Tests↗
PubMed1979

Intraventricular carbachol mimics the effects of light on the circadian rhythm in the rat pineal gland.

Environmental lighting regulates numerous circadian rhythms, including the cycle in pineal serotonin N-acetyltransferase activity. Brief exposure of rats to light can shift the phase of this enzyme's circadian rhythm. Light also rapidly reduces nocturnal enzyme activity. Intraventricular injections of carbachol, a cholinergic agonist, can mimic both of these effects. Light and carbachol presumably act on the suprachiasmatic nucleus of the hypothalamus. These experiments demonstrate the feasibility of using a neuropharmacologic approach to the mechanisms underlying mammalian circadian rhythms.

Acetyltransferases↗
PubMed1979

A new method for the analysis of age trends in CPK levels with application to Duchenne muscular dystrophy.

Measurement of serum creatine phosphokinase (CPK) is the most commonly applied test for carrier detection in Duchenne muscular dystrophy. About two thirds of all carriers have markedly elevated CPK levels. Age correction of CPK measurements would be straightforward if carriers of all ages could be unambiguously identified. Since such identification is impossible, we elaborate an indirect statistical method which is based on Haldane's theory of the balance between selection and mutation for X-linked lethals. We also apply this method to a large body of data gathered on female relatives of Duchenne muscular dystrophy patients and on controls. The results are compared with earlier partial findings.

Age Factors↗
PubMed1979

Photoentrainment, pharmacology, and phase shifts of the circadian rhythm in the rat pineal.

Photoentrainment of circadian rhythms in mammals is mediated by the retinohypothalamic projection to the suprachiasmatic nucleus of the hypothalamus. It should therefore be possible to mimic or block the effects of light on the circadian pacemaker with appropriate pharmacological agents. Such agents and their effects should be useful in identifying the neurotransmitters involved in photoentrainment and their mechanisms of action on the circadian pacemaker. The effects of light on the circadian rhythm in rat pineal serotonin N-acetyltransferase activity are described. Carbachol, a cholinergic agonist, was found to mimic the effects of light on this rhythm, including the acute reduction of nocturnal activity and phase-shifting of the free-running rhythm. These results raise the possibility that acetylcholine is involved in the photoentrainment of mammalian circadian rhythms.

Acetylcholine↗
PubMed1978

Serum pyruvate-kinase (PK) and creatine-phosphokinase (CPK) in progressive muscular dystrophies.

PK and CPK have been determined in the serum from 208 individuals including 70 normal controls (61 adults and 9 children) and 138 patients with a variety of neuromuscular disorders. In adult controls the mean activity (+/- SE) for PK is 1.2 +/- 0.05 mumol/ml/h. In normal children PK activity was about twice as high as in normal adults and decreases with increasing age. In 26 patients with Duchenne dystrophy the range of serum PK was 4.0-150.4 and in 17 individuals with the Becker type, 3.0 to 148.7. All had elevated PK and CPK levels. Eighteen of 20 patients with the facio-scapulo-humeral (FSH) from of muscular dystrophy had increased PK while only 9 had elevated CPK. Regression analyses have shown an inverse correlation between PK levels and age (or degree of disability in DMD). Kinetic and electrophoretic studies indicate that the PK isozyme found in the serum from affected patients and from heterozygotes for the DMD gene is mainly the M1 type PK, which is the only PK isozyme found in skeletal muscle and brain and the major component from myocardium.

Adolescent↗
PubMed1978

Sensitivity and cyclic nucleotides in the rat pineal gland.

beta-Adrenergic stimulation induces serotonin N-acetyltransferase (SNAT) activity in the rat pineal gland. The magnitude and some of the characteristics of this response vary as a function of the gland's previous exposure to stimulation. A period of stimulation results in a subsensitive response to subsequent stimulation. A period without stimulation provides a supersensitive response to subsequent stimulation. Investigations concerned with the mechanisms regulating the rat pineal's sensitivity to beta-adrenergic stimulation are described. These have focused on the regulation of cyclic AMP metabolism. Several of the components involved in the induction of SNAT activity appear to participate in the regulation of sensitivity. These include the beta-adrenergic binding sites, the catecholamine-sensitive adenylate cyclase, the cyclic nucleotide phosphodiesterase, and the cyclic AMP-dependent protein kinase. Thus, the rat pineal's sensitivity to beta-adrenergic stimulation appears to be regulated at multiple sites. Other investigations have focused on the regulation of pineal cyclic GMP metabolism. Unlike cyclic AMP, the stimulation of cyclic GMP synthesis requires the presence of intact nerve endings and of extracellular calcium. Some of the characteristics of pineal cyclic GMP regulation are described.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1978

Effects of reproductive compensation and genetic drift on X-linked lethals.

A revival of interest in Haldane's equilibrium theory for X-linked lethals has been stimulated by the introduction of accurate tests for the detection of female heterozygotes in Lesch-Nyhan disease. Application of these tests appears to indicate an excess of familial cases. This excess can be attributed to ascertainment bias, a difference in female and male mutation rates, genetic drift, and reproductive compensation. Reproductive compensation will be particularly effective in increasing the proportion of familial cases if (1) birth control is widespread; (2) selection against affected males acts in utero; (3) affected sons show symptoms at an early age; and (4) sons are more highly valued than daughters. We demonstrate how only a few generations of reproductive compensation are sufficient to achieve an approximate equilibrium between selection and mutation showing a high proportion of familial cases. We also discuss the random fluctuations around equilibrium caused by genetic drift.

Contraception↗
PubMed1977

Efflux of cyclic nucleotides from rat pineal: release of guanosine 3',5'-monophosphate from sympathetic nerve endings.

Potassium and norepinephrine stimulate the efflux of adenosine 3',5'-monophosphate (cyclic AMP) and guanosine 3',5'-monophosphate (cyclic GMP) from intact pineal glands. The postsynaptic beta-adrenergic receptor mediates the efflux of cyclic AMP. In contrast, the efflux of cyclic GMP requires calcium and intact nerve endings. It appears that sympathetic nerve endings may release cyclic GMP into the synaptic space.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1977

The spectrum of myopathies in the city of São Paulo.

A fifteen-year study was made in the neurologic clinic of the school of medicine, of the City of Sao Paulo; 466 patients were examined clinically and with EMG determination of enzymes, biopsies and genetic counsel. The diagnosis varied much and some important findings at heart level, with overload, were discovered in some cases. In the cases in which the diagnosis was not confirmed; CPK was determined, which was increased in all cases, but was not so with GOT, GPT and LDH. A family pattern was found in the Duchenne Becker distrophy, limb-girdle syndrome, fascioscapulohumeral and oculopharyngeal. The biopsy exposed 15 of the 18 polymyositis cases. Genetic counsel was given to heterozygotes with PMD genes of great risk of presentation. An acute stage, detected by CPK dosage, was foreseen for adolescent heterozygotes.

Adult↗