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S Rubinstein

Publications and source records attributed to S Rubinstein.

60 records · Page 4Linked to original sources
PubMedDate not supplied

Mitogen-activated protein kinase and cell cycle progression during mouse egg activation induced by various stimuli.

A very sensitive method was established for detecting the activity of mitogen-activated protein (MAP) kinase in mouse eggs, and used to follow temporal changes of this kinase during fertilization and spontaneous or chemically-induced parthenogenic activation. MAP kinase activity increased between 1 and 2.5 h post-insemination, at which time the second polar body was emitted and sperm chromatin was dispersed; its activity decreased sharply at 8 h. when pronuclei were formed. Both calcium ionophore A23187 and ethanol simultaneously induced pronuclear formation and MAP kinase inactivation in aged eggs 8 h after incubation but less effectively in fresh eggs. The protein kinase inhibitor staurosporine induced pronuclear formation and MAP kinase inactivation more quickly than other treatments, with MAP kinase inactivation occurring slightly proceeding pronuclear formation. Okadaic acid, a specific inhibitor of protein phosphatase 1 and 2A, induced increase in MAP kinase activity, and overcame pronuclear formation induced by various stimuli. MAP kinase inactivation preceded pronuclear formation in eggs spontaneously activated by aging in vitro, perhaps due to cytoplasmic degeneration and thus delayed response of nuclear envelope precursors to MAP kinase inactivation. These data suggest that MAP kinase is a key protein kinase regulating the events of mouse egg activation. Increased MAP kinase activity is temporally correlated with the second polar body emission and sperm chromatin decondensation. Although different stimuli (including sperm) may initially act through different mechanisms, they finally inactivate MAP kinase, probably by allowing the action of protein phosphatase, and thus induces the transition to interphase.

Animals↗
PubMedDate not supplied

Sudden death in adolescent asthma.

There has been an increase in mortality from asthma in the adolescent age group in the past several years. Although the exact cause of this is not known, a number of factors probably contribute. We have identified four areas of major concern which we believe place adolescents with asthma at high risk. These include physiological factors such as night-time worsening of disease (or "dipping"), non-compliance with the medical regimen, stress associated with daily living and parental expectation, and depression/suicide with asthma as the modality. Identification of those individuals who are at risk and intervention into the contributory factors may reduce asthma deaths.

Adolescent↗
PubMedDate not supplied

A novel method for evaluating the acrosomal status of mammalian spermatozoa.

A novel method was developed to evaluate the acrosomal status of mammalian spermatozoa. The method is based on the ability of the lectin Pisum sativum agglutinin (PSA) to bind specifically to glycoproteins of the acrosomal matrix released during the acrosome reaction. The amount of released acrosomal content is proportional to the fraction of spermatozoa that underwent acrosome reaction. The released glycoproteins present in the supernatant separated from the cells were detected via an ELISA-like assay. The authors suggest that one of these glycoproteins might be the acrosin as identified by anti-acrosin antibodies, using Western blot analysis. The new method (demonstrated here with ram and bull spermatozoa) correlates well with the results obtained by conventional methods. Its advantages are simplicity, objectiveness, rapidity, and low cost. In addition, many samples can be processed in parallel. The method can be used in experimental as well as clinical applications.

Acrosin↗