Comparisons of the molecular evolutionary process at rbcL and ndhF in the grass family (Poaceae)

We examine rate heterogeneity among evolutionary lineages of the grass family at two plasmid loci, ndhF and rbcL, and we introduce a method to determine whether patterns of rate heterogeneity are correlated between loci. We show both that rates of synonymous evolution are heterogeneous among grass lineages and that are heterogeneity is correlated between loci at synonymous sites. At nonsynonymous sites, the pattern of rate heterogeneity is not correlated between loci, primarily due to an aberrant pattern of rate heterogeneity at nonsynonymous sites of rbcL. We compare patterns of synonymous rate heterogeneity to predictors based on the generation time effect and the speciation rate hypotheses. Although there is some evidence for generation time effects, neither generation time effects nor speciation rates appear to be sufficient to explain patterns of rate heterogeneity in the grass plastid sequences.      

内毒素分子结构与肠源性感染

研究表明,内毒素在肠源性感染发病中起重要作用。本文旨在观察内毒素分子结构中的不同组分与肠源性感染的关系。结果示内毒素分子结构中核心多糖链的终末片段的沙门氏菌内毒素(wildtype)及内毒素Ra和Rb造成肠源性感染的发病率分别为54％,83％和92％;而缺乏多糖链终末片断的内毒素Rc,Rd和Re及类脂A均末能造成肠源性感染。核心多糖链的终末片段是内毒素造成肠源性感染的分子学基础。     

Proteins associated with rabbit reticulocyte mRNA caps during translation as investigated by photocrosslinking.

This laboratory previously detected by UV crosslinking a number of proteins associated with cytoplasmic mRNA in mammalian cells, and the data suggested that they are involved in translation. To find out which proteins are associated with caps we made use of reticulocyte mRNA specifically labeled in the cap with 32P together with a cell-free translation system and UV crosslinking. Approximately 8 bands corresponding to proteins crosslinked to the cap itself have been detected by polyacrylamide gel electrophoresis after UV crosslinking and digestion with RNases or tobacco pyrophosphatase. All but one were specific for methylated caps. One was similar in size and partial peptide map to a cap-binding protein, CBP I, previously identified in other laboratories, and most of the others corresponded to proteins previously known to be associated with mRNA but not known to be associated with caps. The results suggest that most mRNA-associated proteins are associated with caps or poly(A). Also, the number of cap-associated proteins may be greater than previously suspected.     

Seasonal variation and time trends in childhood asthma in England and Wales 1975-81.

In England and Wales hospital admissions for childhood asthma almost trebled over the period 1975-81. This may have reflected a true increase in the incidence of acute asthma, a swing from primary to hospital care, or both. The trend was not due to a change in diagnostic fashion. Monthly admissions showed a pronounced seasonal variation with fewest admissions in winter, rising in spring and early summer to peak in the autumn. A deep admission trough was present in August. The monthly admission profile was very similar throughout England and Wales, suggesting that major "trigger" factors were responsible.     

Antisense RNA decreases AP33 gene expression and cytoadherence by <Emphasis Type="Italic">T. vaginalis</Emphasis>

Background  

Host parasitism by Trichomonas vaginalis is complex. Adherence to vaginal epithelial cells (VECs) is mediated by surface proteins. We showed before that antisense down-regulation of expression of adhesin AP65 decreased amounts of protein, which lowered levels of T. vaginalis adherence to VECs. We now perform antisense down-regulation of expression of the ap33 gene to evaluate and confirm a role for AP33 in adherence by T. vaginalis. We also used an established transfection system for heterologous expression of AP33 in T. foetus as an additional confirmatory approach.     

The digestive strategy and efficiency of the West Indian manatee, Trichechus manatus

During the winters of 1982/83 and 1983/84, samples of digesta were collected from nine sites along the gastrointestinal tracts of seven West Indian manatees, Trichechus manatus. The voluminous large intestine of the manatee is responsible for considerable water reabsorption, as well as being the major site of organic matter, nitrogen and crude fat digestion. Cellulose digestion occurs primarily in the cecum and anterior portion of the colon in a pattern similar to terrestrial nonruminant herbivores like the horse. Overall digestibility coefficients for organic matter (71%), nitrogen (61%) and crude fat (77%) are comparable to those of terrestrial herbivores. Manatees have one of the highest digestibility coefficients for cellulose (80%) of any known mammalian herbivore. This high efficiency of cellulose digestion is due primarily to an extremely slow rate of passage. In addition, it appears that seagrasses may be more digestible than terrestrial forages, possibly due to their relatively low lignin content.     

Epileptic seizures after a first stroke: the Oxfordshire Community Stroke Project.

OBJECTIVE: To describe the immediate and long term risk of epileptic seizures after a first ever stroke. DESIGN: Cohort study following up stroke survivors for 2 to 6.5 years; comparison with age specific incidence rates of epileptic seizures in the general population. SETTING: Community based stroke register. SUBJECTS: 675 patients with a first stroke, followed up for a minimum of 2 years. MAIN OUTCOME MEASURES: Occurrence of single and recurrent seizures. RESULTS: 52 patients had one or more post stroke seizures; in 25 the seizures were recurrent. The 5 year actuarial risk of a post stroke seizure in survivors (excluding 19 patients with a history of epilepsy and 3 patients in whom the seizure occurred shortly before death from another cause) was 11.5% (95% confidence interval 4.8% to 18.2%). The relative risk of seizures, in comparison with the general population, was estimated at 35.2 in the first year after stroke and 19.0 in year 2. The risk of seizures was increased in survivors of subarachnoid and intracerebral haemorrhage (hazard ratio for intracranial haemorrhage v cerebral infarction 10.2 (3.7 to 27.9)). The risk of seizures after ischaemic stroke was substantial only in patients presenting with severe strokes due to total anterior circulation infarction. Only 9 of 295 patients (3%) independent one month after stroke suffered a seizure between 1 month and 5 years (actuarial risk 4.2% (0.1% to 8.3%)). CONCLUSION: Stroke patients have about an 11.5% risk of single or recurrent seizures in the first 5 years after a stroke. Patients with more severe strokes or haemorrhagic strokes are at higher risk.