Inositol 1,4,5-trisphosphate (IP3) induced rapid formation of thromboxane B2 in saponin-permeabilised human platelets: mechanism of IP3 action

The mechanism of IP3-induced activation of saponin-permeabilised platelets has been examined. Saponin permeabilization resulted in the leakage of low-Mr substances into and from the cells without loss of cytoplasmic proteins. Addition of IP3 rapidly induced a dose-related formation of thromboxane B2 and release into the medium, leading to the responses of shape change, aggregation and [14C]5HT release. These responses were inhibited by the thromboxane A2 receptor antagonist AH23848. The IP3-induced release of 45Ca from intracellular stores was not affected by indomethacin. Synthesis of thromboxane was inhibited if Ca2+ elevation was prevented by using Ca-EGTA buffers during permeabilization. These studies indicate that IP3-induced activation was due to Ca2+ mobilisation leading to phospholipase activation and thromboxane synthesis.     

Immunologic effects of interleukin 2 in primary immunodeficiency diseases

Five children with primary deficiencies of T cell function were studied to assess the effects of highly purified exogenous Interleukin 2 (IL 2) on their in vitro T cell responses. The lymphocytes from one child with Nezelof's T cell deficiency demonstrated absence of endogenous IL 2 production and improved proliferative responses to mitogen or alloantigen in the presence of exogenous IL 2. Moreover, during in vitro mixed lymphocyte culture in the presence of exogenous IL 2, his lymphocytes were able to develop into cytotoxic effector cells. A second child with Nezelof's syndrome demonstrated a different type of defect. The lymphocytes from this child had less impairment of endogenous IL 2 production. Although IL 2 increased the proliferation of his cells in response to PHA, similar augmentation was not seen after stimulation with OKT3 or alloantigen. In cell-mediated cytotoxicity assays, after mixed lymphocyte culture, natural killer-like activity was strongly boosted in the cultures that contained IL 2, but T cell-mediated cytotoxicity was not. The lymphocytes from three patients with severe combined immunodeficiency did not show improved proliferative responses in the presence of IL 2. Thus, only one of the five patients demonstrated the combination of defective endogenous IL 2 production, but preservation of the ability to respond appropriately to exogenous IL 2. This child may therefore have suffered from a T cell defect pathophysiologically similar to that seen in nude or aged mice.     

Evaluation of the phagocytosis of microspheres in V79 cells by flow cytometry

Phagocytosis of microspheres in V79 Chinese hamster lung cells was investigated by flow cytometry. Fluorescent microspheres (1.8 micron diameter) were used as the ingesta. Change in the number of V79 cells containing fluorescent microspheres was measured as an index of phagocytic activity. With time there was a sigmoidal increase in cells containing microspheres. The phagocytosis of microspheres is partially explained by two parameters introduced to describe the sigmoidal curves.     

Influence of paternally imprinted genes on development.

The parental origin of chromosomes is critical for normal development in the mouse because some genes are imprinted resulting in a predetermined preferential expression of one of the alleles. Duplication of the paternal (AG: androgenones) or maternal (GG/PG: gynogenones/parthenogenones) genomes will result in an excess or deficiency of gene dosage with corresponding phenotypic effects. Here, we report on the effects of paternally imprinted genes on development following introduction of the AG inner cell mass into normal blastocysts. There was a striking increase in embryonic growth by up to 50%, and a characteristic change in embryonic shape, partly because of the corresponding increase in length of the anterior-posterior axis. These changes, between e12-e15, were proportional to the contribution from AG cells to the embryo. However, a contribution of AG cells in excess of 50% was invariably lethal as development progressed to e15. A limited number of chimeras were capable of full-term development provided there was a relatively low contribution from AG cells. The distribution of AG cells in chimeras was not uniform, especially later in development when there was a disproportionate presence of AG cells in the mesodermally derived tissues. Their contribution was consistently greater in the heart and skeletal muscle, but was considerably lower in the brain. Chimeras detected after birth were either dead or developed severe abnormalities of the skeletal elements, particularly of the ribs which were enlarged, distorted and fused, with greatly increased cartilaginous material with an absence of normal ossification. These phenotypic effects in chimeras are reciprocal to those observed in the presence of GG/PG cells, which resulted in a substantial size reduction approaching 50%.(ABSTRACT TRUNCATED AT 250 WORDS)     

On the Estimation of Mean Infecundable Period Following Childbirth (Using Information on Lactation Period)—A Competing Risk Theory Approach

The methodological paper envisages to provide two measures of infecundable period following childbirth; one based on the lactation period when expiry period of amenorrhoea (P.P.A.) follows the same immediately. The other one is based on P.P.A. when expiry of P.P.A. precedes the lactation period. The weighted average of the two measures (duly weighted by the probabilities of both the events) has been given as the estimate of the mean infecundable period. A competing risk oriented approach is adopted to evolve the methodology.     

Expanded bed protein A affinity chromatography of a recombinant humanized monoclonal antibody: process development, operation, and comparison with a packed bed method.

We show that expanded bed protein A affinity chromatography using Streamline rProtein A media is an efficient method for purifying a recombinant humanized monoclonal antibody from unclarified Chinese hamster ovary cell culture fluid and that it provides purification performance comparable to using a packed bed. We determined that the dynamic capacity of the expanded bed media is related to flow rate (measured in column volumes per hour) by a power function, which allows a high capacity at a low flow rate. At 250 cm h-1 with a 25 cm bed height (10 column volumes h-1), the dynamic capacity is 30 g l-1. The yield and purity (measured by the amount of host cell proteins, DNA, SDS-PAGE, and turbidity) of the antibody purified by expanded bed is comparable to the yield and purity obtained on a standard packed bed method using Prosep A media.     

Altered fatty acid composition in regulatory mutants of Streptomyces cinnamonensis

Abstract cDNA-RNA liquid hybridization analysis was used to compare the RNA sequence homology between two members of the Nudaurelia β virus family, Trichoplusia ni virus ( T.ni V) and Dasychira pudibunda virus ( D.p V). Heterologous hybridization experiments demonstrated that these viruses shared little sequence homology. Using oligo(dT) chromatography and oligo(dT)_12–18 as a primer for cDNA synthesis it was shown that neither T.ni V nor D.p V RNA genomes possess a poly(A) tract at the 3' end.