Phosphoinositide hydrolysis in mitogen-stimulated human peripheral-blood T lymphocytes.

Both phytohaemagglutinin and antibodies to the CD3 molecule induced proliferation and phosphoinositide hydrolysis in human peripheral-blood T lymphocytes, but the magnitude of the inositol phosphate response was small and the rate of accumulation slow [significant increases in Ins(1,4,5)P3 were observed only after 10 min]. Hence this response differs from the well-characterized Ins(1,4,5)P3 responses of many other systems. This slow response, its abrogation in Ca2+-depleted medium, the slow and maintained increase in Ca2+ as measured by Quin-2, and the ability of the Ca2+ ionophore A23187 to stimulate Ins(1,4,5)P3 accumulation all suggest that the increase in Ins(1,4,5)P3 occurs, at least in part, as a result of receptor-mediated Ca2+ influx in mitogen-stimulated T lymphocytes.     

Taxonomic significance of differences in DNA methylation within the 'Mycoplasma mycoides cluster' detected with restriction endonucleases MboI and DpnI

DNA from 22 strains belonging to the ' Mycoplasma mycoides cluster' was tested for methylation of adenine in GATC sequences by its resistance or susceptibility to digestion by the restriction endonucleases MboI , which is inhibited by the methylation, or DpnI , which requires the methylation. Strains of bovine serogroup 7, M. mycoides subsp. mycoides SC, and some M. mycoides subsp. capri strains plus M. capricolum strain Cal Kid lacked the methylation, whereas other strains of M. mycoides subsp. capri and of M. capricolum , plus the F38-like and M. mycoides subsp. mycoides LC strains, possessed it. We conclude that this simple test could provide a valuable criterion in identifying these mycoplamas.     

The conodont controversies

The discovery of fossilized conodont soft tissues has led to suggestions that these enigmatic animals were among the earliest vertebrates and that they were macrophagous, using their oropharyngeal skeletal apparatus to capture and process prey. These conclusions have proved controversial. There is now a consensus that conodonts belong within the chordates, but their position within the clade is hotly debated. Resolution of these questions has major implications for our understanding of the origin of the vertebrates and the selective pressures that led to the development of the vertebrate skeleton.     

A spectral probe near the subunit catalytic site of glutamine synthetase from Escherichia coli. Reduced pyridoxal 5'-phosphate.enzyme complexes.

In order to label phosphate binding sites, unadenylylated glutamine synthetase from Escherichia coli has been pyridoxylated by reacting the enzyme with pyridoxal 5'-phosphate followed by reduction of the Schiff base with NaBH4. A complete loss in Mg2+-supported activity is associated with the incorporation of 3 eq of pyridoxal-P/subunit of the dodecamer. At this extent of modification, however, the pyridoxylated enzyme exhibits substantial Mn2+-supported activity (with increased Km values for ATP and ADP). The sites of pyridoxylation appear to have equal affinities for pyridoxal-P and to be at the enzyme surface, freely accessible to solvent. At least one of the three covalently bound pyridoxamine 5'-phosphate groups is near the subunit catalytic site and acts as a spectral probe for the interactions of the manganese.enzyme with substrates. A spectral perturbation of covalently attached pyridoxamine-P groups is caused also by specific divalent cations (Mn2+, Mg2+ or Ca2+) binding at the subunit catalytic site (but not while binding to the subunit high affinity, activating Me2+ site). In addition, the feedback inhibitors, AMP, CTP, L-tryptophan, L-alanine, and carbamyl phosphate, perturb protein-bound pyridoxamine-P groups. The spectral perturbations produced by substrate and inhibitor binding are pH-dependent and different in magnitude and maximum wavelength. Adenylylation sites are not major sites of pyridoxylation.     

Babesia major: protection of intact calves against homologous challenge by the injection of irradiated piroplasms.

Blood from a splenectomized calf infected with Babesia major was divided into 20 ml aliquots which were γ-irradiated at doses of 0, 23.3, 27.3, 31.4, 35.4 and 39.5 krad and then inoculated into groups of three intact calves. Animals receiving non-irradiated blood had typical mild B. major reactions, but those receiving blood irradiated at 23.3, 27.3 and 31.4 krad and 2 of 3 receiving blood irradiated at 35.4 krad had minimal reactions. The remaining 4 animals had no detectable parasitaemic reactions. When the calves were challenged with a similar number (6.0 × 10⁹) of homologous parasites, they were all immune with the exception of the 4 animals which had not reacted initially. The immune status of individual cattle was reflected accurately in the results of the micro-ELISA test, which detected a significant rise in serum antibody titre of the 4 susceptible animals 7 days after challenge.     

Ecological study of social fragmentation,poverty, and suicide

ObjectivesTo investigate the association between suicide and area based measures of deprivation and social fragmentation.DesignEcological study.Setting633 parliamentary constituencies of Great Britain as defined in 1991.ResultsMortality from suicide and all other causes increased with increasing Townsend deprivation score, social fragmentation score, and abstention from voting in all age and sex groups. Suicide mortality was most strongly related to social fragmentation, whereas deaths from other causes were more closely associated with Townsend score. Constituencies with absolute increases in social fragmentation and Townsend scores between 1981 and 1991 tended to have greater increases in suicide rates over the same period. The relation between change in social fragmentation and suicide was largely independent of Townsend score, whereas the association with Townsend score was generally reduced after adjustment for social fragmentation.ConclusionsSuicide rates are more strongly associated with measures of social fragmentation than with poverty at a constituency level.

Key messages

• Place of residence may affect health, and mortality from most common diseases tends to be higher in areas characterised by low socioeconomic position
• Research dating back over 100 years suggests that social fragmentation may influencesuicide
• In the 1980s and 1990s, parliamentary constituencies with high levels of social fragmentation had high rates of suicide, independent of deprivation
• Constituencies with the greatest increases in social fragmentation between 1981 and 1991 also had the greatest increases in suicide rates over the same period
• Any targeting of suicide prevention may be more effective if aimed at socially fragmented rather than deprived areas

     

Altered bleomycin-induced lung fibrosis in osteopontin-deficient mice

Osteopontin is a multifunctional matricellular protein abundantly expressed during inflammation and repair. Osteopontin deficiency is associated with abnormal wound repair characterized by aberrant collagen fibrillogenesis in the heart and skin. Recent gene microarray studies found that osteopontin is abundantly expressed in both human and mouse lung fibrosis. Macrophages and T cells are known to be major sources of osteopontin. During lung fibrosis, however, osteopontin expression continues to increase when inflammation has receded, suggesting alternative sources of ostepontin during this response. In this study, we demonstrate immunoreactivity for osteopontin in lung epithelial and inflammatory cells in human usual interstitial pneumonitis and murine bleomycin-induced lung fibrosis. After treatment with bleomycin, osteopontin-null mice develop lung fibrosis characterized by dilated distal air spaces and reduced type I collagen expression compared with wild-type controls. There is also a significant decrease in levels of active transforming growth factor-beta(1) and matrix metalloproteinase-2 in osteopontin null mice. Type III collagen expression and total collagenase activity are similar in both groups. These results demonstrate that osteopontin expression is associated with important fibrogenic signals in the lung and that the epithelium may be an important source of osteopontin during lung fibrosis.