Biomedical subjects
Publications and source records attributed to M A Sharaf.
Dosimetric properties of g-irradiated modern coral and bioactive glass (Bio-G) samples analyzed with electron spin resonance (ESR) have been separately reported (Hassan et al., 2004; Sharaf and Hassan, 2004) and compared with alanine. These are combined here to allow a three-way comparison between these materials.
Bioglass (Bio-G) samples were irradiated with 60Co gamma-rays to study radicals for dosimetric materials with electron spin resonance (ESR). The ESR spectrum of Bio-G is characterized by two main signals. The first signal at g approximately = 4.3 corresponds to Fe3+ impurities and the second signal at g approximately = 2.0130 with line-width 10.85 G is ascribed as a hole center. The gamma-ray dose response and thermal stability were studied to establish the suitability of bioglass as an ESR dosimeter. A radical formation efficiency, G-value, of 0.53 +/- 0.11 was obtained. The lifetime of radicals and the activation energy were estimated from Arrhenius plots to be approximately 255 +/- 46 days and 0.71 eV, respectively.
Division in chemostat cultures of Chlamydomonas reinhardi was synchronized by daily cycles of both temperature and light. In response to 8 h cool (20 degrees C) - dim light/16 h warm (28 degrees C) - bright light cycles and continuous dilution that removed half the cells daily, the cells replicated nuclear DNA late in the warm-bright phase; released an average of two daughter zoospores early in the warm-bright phase of the next cycle. In these synchronized green algal cultures all ATP and most cAMP were intracellular; most cGMP (approximately 91%) was extracellular. Early in the warm-bright phase ATP doubled after which cAMP level fell 25%. During DNA replication cAMP level doubled, rising to a modest peak reached as replication ended.
An enzyme exhibiting both 3 beta and 20 alpha steroid reductase activities from calf fetal red blood cells was purified to homogeneity as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 3 beta,20 alpha-Hydroxysteroid oxidoreductase (3 beta,20 alpha-HSD) was found to be a single-stranded polypeptide with a molecular weight of 55 000 +/- 1 000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Sephadex G-100 chromatography. The amino acid composition of 3 beta,20 alpha-HSD was obtained. 17 beta-Hydroxy-5 alpha-androstan-3-one and progesterone were substrates for the enzyme's 3 beta and 20 alpha reductase activities, respectively, which required NADPH for both 3 beta [Km = 9.4 microM; Vmax = 2.4 nmol min-1 (nmol of enzyme)-1] and 20 alpha [Km = 2.5 microM; Vmax = 2.4 nmol min-1 (nmol of enzyme)-1] reductase activities. 17 beta-Hydroxy-5 alpha-androstan-3-one competitively inhibited (Ki = 35 microM) 20 alpha reduction of progesterone. Incubating 3 beta,20 alpha-HSD with 19-nortestosterone 17-bromoacetate at pH 7.0 and 25 degrees C caused simultaneous, time-dependent, and irreversible losses of 3 beta and 20 alpha activities by a first-order kinetic process. Similar incubations with either of the 3 beta or 20 alpha substrates present at concentrations equal to their respective Km values practically doubled the time required for loss of 3 beta and 20 alpha enzyme activities. These data lead us to conclude that the active site of 3 beta,20 alpha-HSD contains 3 beta and 20 alpha dual activity.
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NADPH-dependent 20 alpha-hydroxysteroid oxidoreductase (20 alpha-HSD; EC 1.1.1.149) from bovine fetal erythrocytes was obtained for the first time free of hemoglobin by a new 2,500-fold purification scheme. This was achieved by a sequence of calcium phosphate gel absorption, ammonium sulfate fractionation, and affinity chromatography. The present results lead us to believe that the NADPH-dependent 3 beta-hydroxysteroid oxidoreductase activity, which was co-purified with 20 alpha-activity, may originate at the active site of 20 alpha-HSD (2).
Forty-three previously untreated Egyptian patients with Hodgkin's disease and thirty-five patients with non-Hodgkin lymphoma were studied with several readily available tests of immune function, number of peripheral blood lymphocytes, delayed hypersensitivity to two recall antigens, in vitro blastoid transformation by PHA, the capacity of E-rosette formation and surface marker criteria. The results were correlated to the histology, stage of disease and to the presence of general symptoms and signs.
The sequence of a protein can be graphed as a discrete function and a cross-correlation between any two such number sets produces a similarity score. The scores are used to prepare a phylogenetic tree involving hierarchical cluster analysis, non-linear mapping, and minimal spanning routines. Changes are suggested in the sequences of cytochrome c's from Mediterranean fruit fly, locust, and rattlesnake. The method is faster than existing procedures and does not require human intervention at any stage.