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Biomedical subjects

M Levi

Publications and source records attributed to M Levi.

At least 343 records · Page 19Linked to original sources
PubMed1980

A calcium-stimulated alkaline phosphatase associated with synaptic vesicles.

Synaptic vesicles isolated from bovine cerebral cortex were found to contain alkaline phosphatase activity towards p-nitrophenylphosphate and alpha-naphthyl phosphate, but not towards pyridoxal phosphate. The enzyme had an apparent molecular weight of 125,000 and co-purified with the synaptic vesicles in parallel with the specific neurotransmitter content and with the loss of contaminating components, whereas the major phosphatase which was present in the brain homogenate, with an apparent molecular weight of 140,000 purified away. The optimal pH for the enzyme activity on p-nitrophenylphosphate was 9.8. At this pH the activity was 33.4 nmol/mg protein/min, and the apparent Km value was 0.31 +/- 0.05 mM. The pH dependency of the synaptic vesicle phosphatase activity towards p-nitrophenylphosphate differed from that of the Ca2+/Mg2+-dependentt ATP hydrolysis by the synaptic vesicles. Upon mild digestion of lyzed vesicles with trypsin, phosphatase activity was reduced whereas the ATPase activity was retained suggesting that the phosphatase and the ATPase are two different enzymes. The phosphatase was reversibly inhibited by ethyleneglycol bis (aminoethyl ether) N,N'-tetracetic acid (EGTA) and activity was restored by the addition of an equimolar amount of CA2+. Magnesium ions could restore only 30% of the activity. The activity of the synaptic vesicle phosphatase was not affected by o-phenanthroline, zinc ion or by cAMP. Tetranitromethane inactivated the enzyme irreversibly, whereas phenylmethanesulfonylfluoride diisopropylfluorophosphate and p-hydroxymercurybenzoate inhibited the activity partially. The enzyme did not have a diesterase activity. Adenosine mono-, di- and triphosphate inhibited the p-nitrophenylphosphatase activity and were also hydrolyzed by the vesicle preparation. However, the different kinetic parameters obtained with the nucleotide as inhibitors or as substrates suggest that additional enzymes are involved in the hydrolysis of the adenine nucleotides in vesicle preparation.

Alkaline Phosphatase↗
PubMed1980

Personality patterns among hospitalized vs. incarcerated psychopaths.

Subjected MMPI profiles of 80 hospitalized and 80 incarcerated white, male psychopathic personalities to a formal clustering procedure from which five primary types emerged. These types differed along four dimensions of profile pattern, and patients were distinguished from prisoners by a greater frequency of types in which psychopathic features were combined with nonpsychopathic forms of psychopathology. A higher average profile elevation also was obtained for hospitalized than incarcerated Ss, although frequencies of common two-point codes failed to discriminate significantly between these two groups. The results were seen to highlight the heterogeneity of psychopathy, to illustrate the potential of comparative studies of similarly diagnosed Ss from different clinical populations for clarifying this diversity, and to support the practice of deriving MMPI profile types by empirical methods rather than the currently popular two-point code approach.

Adult↗
PubMed1980

Tubulin: an integral protein of mammalian synaptic vesicle membranes.

The major protein in isolated synaptic vesicles from bovine cerebral cortex has been compared to tubulin by sodium dodecyl sulphate-urea polyacrylamide gel electrophoresis, by two-dimensional gel electrophoresis, and by peptide mapping following limited proteolysis of the protein by Staphylococcus aureus protease. The results establish in purified synaptic vesicles the presence of tubulin, which is composed of the alpha and beta subunits. In the presence of ethyleneglycolbis)aminoethyl ether)-N,N'-tetraacetic acid (EGTA) or magnesium in the isolation buffers, the synaptic vesicles contained mainly the alpha-tubulin whereas the beta subunit was less abundant. Similarly, synaptosomal plasma membranes that were prepared in the presence of EGTA also contained more of alpha-tubulin than of the beta subunit. Non-ionic detergents such as Triton X-100 or Nonidet P-40 failed to solubilize the tubulin from the synaptic vesicles. Ionic detergents such as deoxycholate and sodium dodecyl sulphate solubilized all the vesicle proteins, including tubulin. The results indicate that alpha-tubulin is an integral vesicle membrane protein, whereas most of the beta subunit is peripherally attached and can be easily dissociated from the vesicle membrane with EGTA.

Animals↗
PubMed1980

Nuclear division cycle in Neurospora crassa hyphae under different growth conditions.

Treatment with picolinic acid blocked Neurospora crassa nuclei in G1, and recovery from the treatment allowed a synchronous wave of deoxyribonucleic acid synthesis to occur. Nuclei, which appeared as compact globular bodies during the period of blockage, assumed a ring shape during the following S phase, which was also maintained in the G2 phase. The proportion of compact globular nuclei was much higher in hyphae growing at lower rates, whereas that of ring nuclei increased when the hyphae were growing at higher rates. Horseshoe nuclei (probably mitotic nuclei) and double ring nuclei were also observed in growing hyphae, but their frequencies were low and fairly independent of the rate of growth. The length of the S phase of the Neurospora nuclear division cycle was determined to be about 30 min. From the frequencies of the phase-specific nuclear shapes, the durations of the G1 phase and the combined S plus G2 phases were calculated. The results showed that variations in the growth rates of the mycelia were mainly coupled with variations in the G1 phase of the nuclear division cycle. For mycelia growing in minimal sucrose, the lengths of all of the phases of the nuclear division cycle were estimated.

Cell Division↗
PubMed1980

Canonical versus factor analytic perspectives on the structure of associations between the MMPI and the Buss-Durkee Hostility Inventory.

A canonical correlational analysis of MMPI profiles versus Buss-Durkee hostility and aggression scales was conducted, resulting in the identification of a general hostility-aggression-maladjustment dimension and three relatively specific aggression-personality relationships. These findings were contrasted with those obtained from a factor analysis of the combination of both sets of scores. Though often used in previous studies of associations between the Buss-Durkee Hostility Inventory and other measures, factor analysis was seen to be less than optimally suited to such a purpose. It was concluded that canonical correlation is preferable to factor analysis when seeking to clarify the multivariate structure of relationships between two sets of variables.

Journal Article↗
PubMed1980

Functional redundancy and the process of professionalization: the case of registered nurses in the United States.

Registered nurses have been attempting to achieve professional status for nearly a century. Historical investigation of their efforts in the United States and a case study of the 1976 Seattle Nurses' strike indicate major obstacles to the professionalizing project. The most important of these are the inability of the nurses to control the labor supply, and their failure to define or monopolize a distinct set of tasks. One result is functional redundancy: there is no job nurses perform that is not also performed by some other occupation.

History of Nursing↗
PubMed1980

Cellular events in growth and germination of giant conidia of Neurospora crassa.

During growth of conidia in 3.22 M ethylene glycol the increase in the number of the nuclei is proportional to the increase in volume only in the phase of maximum growth rate and is lower in the preceding and in the following periods of growth. DNA synthesis similarly initiates later and decreases faster than protein synthesis. The dilution of ethylene glycol is followed by the germination of giant conidia, which is characterized by the absence of a lag phase, a high degree of synchrony and the formation of more than one germ tube per conidium. The number of germ tubes is dependent on the volume reached by conidia at the end of the treatment and does not increase with time. The resuming of DNA synthesis after germination is preceded by a sharp increase in protein synthesis and the division of almost half of the nuclei and shows a synchronized pattern. Results are discussed in the light of models of growth proposed for eukaryotic cells.

DNA, Fungal↗
PubMed1979

25 Hydroxycholecalciferol levels in Beduin women in labor and in cord blood of their infants.

25 Hydroxycholecalciferol levels were measured in eight Beduin mothers in labor and in the cord blood of their infants, and compared with values in 42 Sephardi Israeli women in labor and the cord blood of their offspring. Beduin baby cord blood had a mean 25 hydroxycholecalciferol concentration of 3.78 ng/ml +/- 3.22 (SD) being about half of their mothers' level in labor. Values in Sephardi women and cord blood were 3 times higher. PTH levels were lower and calcium concentrations were higher in cord blood (P less than 0.001) in both groups when compared to their mothers' blood. The relevance of these findings to the high incidence of infantile rickets and hyypocalcemia in Beduin children is discussed.

Calcium↗
PubMed1978

Determinants of multi-employer bargaining in metropolitan hospitals.

To join with the others or go it alone--that is the question faced by every hospital and health care facility where a unionization drive is either on the horizon or in progress. The factors that have entered into the decisions of hospital trustees and administrators on this touchy problem are the subject of this article. The authors discuss the experiences of the hospital industry in six areas across the country and analyze the factors involved in the evolution of different bargaining structures.

Collective Bargaining↗
PubMed1976

[Alithiasic cholecystopathies. Clinical, diagnostic and therapeutic aspects].

The frequency of alithiasic cholecystitis is considered and the various forms are subdivided into diffuse and localized dyskinesia. Symptomatology is described and the former are indicated as being electively medical and the latter surgical forms whether the condition is congenital or acquired. The various forms of cholecystosis are also distinguished with full documentation. Symptomatological techniques and diagnostic conclusions are illustrated for all forms and personal experience with their therapy reported.

Cholangiography↗