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Biomedical subjects

S Weinman

Publications and source records attributed to S Weinman.

At least 37 records · Page 2Linked to original sources
PubMed1987

Calmodulin in Zajdela hepatoma cell growth.

Calmodulin levels were measured in Zajdela hepatoma cells growing both in vivo and in culture, with respect to the distribution of the cells into G1 and S+G2 phases of the cell cycle and growth conditions. These levels, expressed on a per-microgram of protein basis, were significantly elevated at the G1-S boundary and maintained throughout the remainder of the cell cycle. This elevation of calmodulin took place independently of the culture conditions. Taken together with previous observations, these data suggest that a threshold concentration for calmodulin is required for progression through the cell cycle, DNA synthesis and cell division.

Animals↗
PubMed1986

Immunoelectron microscopic localization of calmodulin and phospholipase A2 in spermatozoa. I.

Using the Lowicryl K4M embedding technique, together with indirect immunoferritin or immunogold labeling on ultra-thin sections, tubulin, calmodulin and phospholipase A2 were distinctly localized in ejaculated bull spermatozoa. Calmodulin was concentrated on the plasma membrane, nucleus, post-acrosomal substance, and, in lesser amounts, between coarse fibers and axonemal microtubules of the flagellum. Phospholipase A2 was distributed evenly along the plasma membrane, nucleus, acrosome, post-acrosomal substance, and in the flagellum, on mitochondria, fibrous sheath, coarse fibers, between coarse fibers and axonemal microtubules. Antibodies to tubulin labeled only axonemal microtubules, including the central pair of microtubules. Patterns of tubulin labeling were identical when ferritin granule- or gold particle-conjugated antibodies were tested. In agreement with our previous biochemical studies demonstrating calmodulin binding to phospholipase A2, concomitant with enhancement of phospholipase A2 activity (Arch Biochem Biophys 241:413, 1985), the overlapping distribution of calmodulin and phospholipase A2 in several parts of the sperm suggests that these proteins may play a concerted role in male gamete function in preparation for or during fertilization. The distinct distribution of tubulin along flagellum microtubules indicates their special function in sperm mobility.

Animals↗
PubMed1986

Calmodulin immunoelectron microscopy: redistribution during ram spermatogenesis and epididymal maturation. II.

Affinity-purified monospecific antibodies and indirect immunogold and immunoferritin labeling on ultra-thin sections of low-temperature Lowicryl K4M-embedded samples were used to study the redistribution of calmodulin in ram spermatids and epididymal spermatozoa at the electron microscopic level. Calmodulin appeared as an integral component of well-defined structures or organelles of these cells. In young spermatids, calmodulin was localized in the nucleus, cytoplasm, and developing acrosome. During spermatogenesis and epididymal maturation, calmodulin left the acrosome to reach the perinuclear substance and finally became concentrated in the post-acrosomal area of the head, although some calmodulin remained associated with the tip of the acrosome. Such a redistribution is consistent with the preferential location of Ca2+ in the post-acrosomal cytoplasm of ejaculated spermatozoa. Calmodulin was also observed in the flagellum associated with the plasma membrane and with the motility apparatus, between coarse fibers and axonemal microtubules. These changes in calmodulin distribution may account for the Ca2+-dependent regulation of spermatogenesis and sperm maturation. Calmodulin therefore appears to be a pleiotropic regulator of male gamete development and functions.

Animals↗
PubMed1985

Calmodulin level and cAMP-dependent protein kinase activity in rat spermatogenic cells and hormonal control of spermatogenesis.

The changes in intracellular calmodulin levels and cAMP-dependent protein kinase activities have been studied in the testis of normally developing and hypophysectomized rats. It appears that the onset of spermatogenesis which occurs on the first days of the postnatal development, is associated with a major (over fivefold) increase in the calmodulin level and enhancement of the cAMP-dependent protein kinase activity. On the contrary, hypophysectomy of adult animals is associated with a progressive decline in the calmodulin level and a rapid and regular decrease in the cAMP-dependent protein kinase activity. Moreover, measurements of the intracellular calmodulin level and cAMP-dependent kinase activity of isolated testicular germ cells or epididymal spermatozoa have shown that testosterone, administered to hypophysectomized rats as subcutaneous implants, maintains the concentration of these regulatory proteins to normal values.

Animals↗
PubMed1984

Changes in calmodulin level after fertilization and during first cleavage in the egg of the urodelan amphibian Pleurodeles waltlii.

We report three significant calmodulin rises related to Pleurodeles waltlii egg fertilization and following developmental events. These elevations are correlated to the major obvious Ca2+-dependent events: Na+-H+ exchange, activation of NAD kinase, triggering of cortical reaction, resumption of meiotic division II, initiation of DNA synthesis and regulation of cell division. Therefore, it is suggested that alterations in calmodulin level in fertilized egg may be part of the Ca2+-dependent regulatory mechanisms which turn on metabolisms, initiate development and govern cell cleavages.

Animals↗
PubMed1983

Evolution of Ca2+- and cAMP-dependent regulatory mechanisms during ram spermatogenesis.

Calmodulin level and cAMP-dependent protein kinase activity of ram germ cells at different stages of spermatogenesis have been determined. Calmodulin levels decrease during maturation. Simultaneously, calmodulin localization changes during cell differentiation. In round, elongating, and elongated spermatids, calmodulin is closely associated with the developing acrosome; in spermatozoa, it becomes present in the postacrosome, the neck region and the tail. Protein kinase activity is relatively low in testicular cells but increases dramatically during epididymal maturation of spermatozoa. A concerted regulation by cAMP and Ca2+ of biochemical events in spermatogenic cells and spermatozoa is suggested.

Animals↗
PubMed1983

Total IgE, specific IgE and prick-tests against foods in common migraine--a prospective study.

A prospective study of total IgE, specific IgE against 12 common foods, and prick-tests with 11 common food allergens was performed on 50 consecutive migraine sufferers. Total IgE levels were found above 100 kU/l for seven patients, but five of them were atopic. Prick-tests and RAST were positive for four and six patients (class 1), respectively. Food challenge on these six patients did not cause any migraine attacks. This study thus indicates a very low frequency of allergic dietary migraine to common foods.

Adolescent↗
PubMed1981

Immunocytochemical and biochemical evidence for the presence of calmodulin in bull sperm flagellum. Isolation and characterization of sperm calmodulin.

Upon fluorescent staining with a goat antibody anti-ram testis calmodulin, washed bull sperm appears to contain calmodulin in the acrosome, in the post acrosomal region, in the neck region probably associated with the implantation plates and thin laminated fibers, and in a sheath around the upper part of the flagellum. Heads and midpieces + tails were separated by elutriation of sonicated sperm. Immunofluorescent labeling of fragments confirms the presence of calmodulin in implantation plates, where sonication disrupted heads from midpieces, and in a sheath around the midpiece and the upper part of the principal piece. These results were confirmed by electrophoretic and radioenzymatic assays of calmodulin in the fragments, using calmodulin-deficient Ca2+/calmodulin-dependent myosin light chain kinase. Small but significant amounts (approx. 3 micrograms per 10 (10) sperm) are found in midpieces + tails vs. approx. 280 micrograms in the same number of heads. These results are in agreement with a recent report from Jones et al. (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 2772-2776. Sperm calmodulin was purified from a whole sperm 1 M KCl extract and found to exhibit the same characteristics as other mammalian calmodulins isolated so far in terms of ultraviolet absorption spectrum and amino acid composition, including one residue of epsilon-N-trimethyllysine. Its behavior upon SDS-polyacrylamide gel electrophoresis was dependent on the presence or absence of Ca2+. The high performance liquid chromatography tryptic peptide maps were similar, if not identical, to mammalian calmodulin maps (Autric et al. (1980) Biochim. Biophys. Acta 631, 139-147). Sperm calmodulin is therefore probably identical to the somatic cell protein.

Amino Acids↗