Alphavirus-induced apoptosis in mouse brains correlates with neurovirulence

Sindbis virus induces apoptotic cell death in cultured cell lines, raising the possibility that apoptosis of infected neurons and other target cells in vivo may contribute to the resulting disease and mortality. To investigate the role of apoptosis in Sindbis virus pathogenesis, infected mouse brains were assayed by the in situ terminal deoxynucleotidyltransferase-mediated dUTP nick end-labeling technique and for DNA ladder formation. Infection with recombinant Sindbis virus strain 633 resulted in widespread apoptosis in newborn mouse brains and spinal cords, but few apoptotic cells were observed following infection of 2-week-old animals. This finding correlates with the age-dependent mortality observed in mice. The more neurovirulent virus TE, which differs from 633 by a single amino acid in the E2 glycoprotein, induced significant apoptosis in brains and spinal cords of 2-week-old animals, consistent with its ability to cause fatal disease in older animals. Double-labeling experiments demonstrated that the apoptotic cells were also infected with Sindbis virus. Thus, Sindbis virus-induced apoptosis appears to be a result of virus infection and is likely to reflect pathogenic mechanisms for other viruses.

Neurogenic genes and vertebrate neurogenesis

The neurogenic genes of the Delta-Notch signalling pathway mediate lateral inhibition--a mechanism that controls cell commitment in many tissues and serves in the developing nervous system to single out cells for a neural fate. Recent work has revealed the outlines of the signal transduction pathway from Notch to the nucleus, has clarified the mechanisms by which lateral inhibition causes adjacent cells to become different, and has shown that vertebrates use essentially the same lateral inhibition machinery as flies and worms to regulate neurogenesis.

Early ear development in the embryo of the zebrafish, Danio rerio

The zebrafish provides an important model for vertebrate inner ear development. The otic placode becomes visible at approximately 16 hours (at 28.5 degrees C) and forms a vesicle with a lumen by cavitation at approximately 18 hours. Two otoliths appear in the lumen by 19.5 hours, and at about 24 hours the first sensory hair cells are seen, grouped in two small patches, one beneath each otolith, corresponding to future maculae. Staining with fluorescent phalloidin reveals 10-20 hair cells in each macula by 42 hours; between 3 days and 7 days the numbers grow to approximately 80 per macula. Neurons of the statoacoustic ganglion are first visible by staining with HNK-1 antibody at about 24 hours. Serial sections and time-lapse films show that the neuronal precursors originate by delamination from the ventral face of the otocyst; the peak period of delamination is from 22 hours to 30 hours. The system of semicircular canals forms between 42 hours and 72 hours by outgrowth of protrusions from the walls of the otocyst to form pillars of tissue spanning the lumen. Three further clusters of hair cells also become visible in this period, forming the three cristae. Thus, by the end of the first week, all key components of the ear are present. Subsequent growth produces thousands more hair cells; additional neurons probably derive from proliferation of neuronal precursors within the ganglion. Although the timetable is species-specific, the principles of inner ear development in the zebrafish seem to be the same as in other vertebrates.

Coinfection with chlamydia and gonorrhoea among pregnant women and bacterial vaginosis

The role of sexual transmission of microorganisms in bacterial vaginosis (BV) is controversial. If sexual intercourse were a risk factor for BV, then we would expect that women with BV would also be coinfected with other sexually transmitted diseases (STD). We investigated the prevalence of STD among pregnant women a low socio-economic status with bacterial vaginosis in Indonesia. Among these women, 23.3% had at least one STD (chlamydia, gonorrhoea, syphilis or trichomoniasis). Chlamydial infection was the most prevalent (19.5%), followed by trichomoniasis (3.8%), gonorrhoea (3.2%) and syphilis (0.4%). Compared to the rates of STD observed in a previous study of all pregnant women (with or without BV) in Indonesia, pregnant women with BV have more than a 2-fold increase in chlamydia (19.5% vs 8.2%) and a 6-fold increase in gonorrhoea (3.2% vs 0.5%). Because detection of BV by Gram stain is easy to perform and economical, detection of BV has potential as a prescreening marker for chlamydia and gonorrhoea among asymptomatic pregnant women of low socio-economic status in Indonesia. Further work is needed to evaluate the usefulness of BV as a prescreening marker for chlamydia and gonorrhoea.

Does ethnicity influence obstetric intervention?

AIMS

To examine whether the high proportion of Polynesian women giving birth at Middlemore Hospital contributes to its low interventional delivery rate.

METHODS

A study of a one-year cohort of women delivering at Middlemore Hospital. Delivery suite records were scrutinised to determine ethnicity and mode of delivery. Statistical comparisons were made.

RESULTS

In Maori, Pacific Island and European women the caesarean section rates were 6.5%, 9.5% and 11.5% respectively. Maori women have a significantly lower rate of caesarean section than Pacific Island women and both groups have a significantly lower rate than European women. The spontaneous vaginal delivery rates in Maori, Pacific Island and European women were 89.0%, 87.4% and 74.8% respectively.

CONCLUSION

The high proportion New Zealand Maori and Pacific Island women contributes to, but does not fully explain, the low interventional delivery rate at Middlemore Hospital.

A mouse model for beta 0-thalassemia

We have used a "plug and socket" targeting technique to generate a mouse model of beta 0-thalassemia in which both the b1 and b2 adult globin genes have been deleted. Mice homozygous for this deletion (Hbbth-3/Hbbth-3) die perinatally, similar to the most severe form of Cooley anemia in humans. Mice heterozygous for the deletion appear normal, but their hematologic indices show characteristics typical of severe thalassemia, including dramatically decreased hematocrit, hemoglobin, red blood cell counts, mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration, as well as dramatically increased reticulocyte counts, serum bilirubin concentrations, and red cell distribution widths. Tissue and organ damage typical of beta-thalassemia, such as bone deformities and splenic enlargement due to increased hematopoiesis, are also seen in the heterozygous animals, as is spontaneous iron overload in the spleen, liver, and kidneys. The mice homozygous for the b1 and b2 deletions should be of great value in developing therapies for the treatment of thalassemias in utero. The heterozygous animals will be useful for studying the pathophysiology of thalassemias and have the potential of generating a model of sickle cell anemia when mated with appropriate transgenic animals.

Isolation and characterization of a beta-D-glucuronidase-producing strain of Escherichia coli serotype O157:H7 in the United States

A phenotypic variant of Escherichia coli serotype O157:H7 (G5101) was isolated from a patient with bloody diarrhea. Strain G5101 does not ferment sorbitol but is beta-D-glucuronidase and urease positive. Serotyping and colony hybridization using a serotype-specific DNA probe confirmed that the isolate was O157:H7. G5101 produces Shiga-like toxins I and II and contains an eae gene that is highly conserved in the O157:H7 serotype. This strain would have been missed by laboratories that screen for the sorbitol-negative, beta-D-glucuronidase-negative phenotype in isolating E. coli O157:H7 from clinical and food specimens.

TB exposure: are you prepared?

1. The elderly have the highest case rates for TB disease. 2. Residents need to be screened for TB infection on admission with a Mantoux skin test. 3. Employees need to be screened for TB by the Mantoux skin test on hire and annually. 4. A chest x-ray is not adequate to screen for TB infection.

The prevalence and prophylaxis of gout in England

The prevalence of gout in England was reported as having nearly doubled in the 1970s to about 3 per 1000, and it is possible that it has continued to increase. There may also have been some change in the level of prophylactic therapy compared with the 44.8% recorded in 1979. In this study, data were provided from their morbidity registers by 40 volunteer practices with a combined population of over 300,000 patients. Analyses of prevalence by age and sex, and of the extent of prophylaxis were made. The male:female ratio and the increase with age found were in line with earlier work, but overall prevalence was much higher at almost 10 per 1000. There was considerable inter-practice variation: 20% of this could be accounted for by the age and sex structure of the practice populations, but neither economic status nor broad geographical factors appeared to be significant, and it did not appear to be due to variation between practices in the level of special interest in gout. Prophylactic therapy--almost entirely allopurinol--was being prescribed for 48% of the sufferers; though practices varied widely in their propensity to give it, as a group the amount of allopurinol they used was close to the national average. The increase found in the prevalence of gout may be related to an increase in obesity in the population.

A cap-binding protein complex mediating U snRNA export

Cap structures are added cotranscriptionally to all RNA polymerase II transcripts. They affect several processes including RNA stability, pre-messenger RNA splicing, RNA export from the nucleus and translation initiation. The effect of the cap on translation is mediated by the initiation factor eIF-4F, whereas the effect on pre-mRNA splicing involves a nuclear complex (CBC) composed of two cap binding proteins, CBP80 and CBP20. A role for CBC in the nuclear export of capped RNAs has also been proposed. We report here the characterization of human and Xenopus CBP20s. Antibodies against recombinant CBP20 prevent interaction of CBC with capped RNAs in vitro. Following microinjection into Xenopus oocytes, the antibodies inhibit both pre-mRNA splicing and export of U small nuclear RNAs to the cytoplasm. These results demonstrate that CBC mediates the effect of the cap structure in U snRNA export, and provide direct evidence for the involvement of a cellular RNA-binding factor in the transport of RNA to the cytoplasm.

Plasma taurine concentrations in normal dogs and in dogs with heart disease

Plasma taurine concentrations were determined in 76 dogs with dilated cardiomyopathy (DCM), 28 dogs with acquired valvular disease (AVD), and 47 normal (control) dogs. The data were collected at 2 referral centers, The Animal Medical Center, New York, NY (AMC), and the University of California, Davis (UCD), and the studies were conducted independently. Different anticoagulants (sodium citrate at AMC and lithium heparin at UCD) were used to collect the plasma samples. Paired analysis of samples showed a significant difference in plasma taurine concentrations, depending on the anticoagulant used. Consequently, results from each clinic were analyzed separately. Plasma taurine concentrations were significantly higher in dogs with AVD (median, 133 nmol/mL; range, 25 to 229 nmol/mL) than in control dogs (median, 63 nmol/mL; range 44 to 224 nmol/mL) and dogs with DCM (median, 72 nmol/mL; range, 1 to 247 nmol/mL) at AMC (P < .001). The number of dogs with AVD at UCD was too small to draw meaningful conclusions. At UCD, the median plasma taurine concentration was 98 nmol/mL (range, 28-169 nmol/mL) in dogs with AVD, 75 nmol/mL (range, 0.1-184 nmol/mL) in dogs with DCM, and 88 nmol/mL (range 52-180 nmol/mL) in control dogs. There were no significant differences in plasma taurine concentrations between dogs with DCM and the control dogs at either hospital. Congestive heart failure and administration of cardiac medication had no significant effect on plasma taurine concentrations. Plasma taurine concentration was low (< 25 nmol/mL) in 17% (13/76) of the dogs with DCM. Seven of the 13 dogs with low plasma taurine concentrations were Cocker Spaniels or Golden Retrievers.(ABSTRACT TRUNCATED AT 250 WORDS)

Primary neurogenesis in Xenopus embryos regulated by a homologue of the Drosophila neurogenic gene Delta

X-Delta-1, a Xenopus homologue of the Drosophila Delta gene, is expressed in the early embryonic nervous system in scattered cells that appear to be the prospective primary neurons. Ectopic X-Delta-1 activity inhibits production of primary neurons and interference with endogenous X-Delta-1 activity results in overproduction of primary neurons. These results indicate that the X-Delta-1 protein mediates lateral inhibition delivered by prospective neurons to adjacent cells, and that commitment to a neural fate in vertebrates is regulated by Delta-Notch signalling as in Drosophila.

Expression of a Delta homologue in prospective neurons in the chick

The product of the Delta gene, acting as ligand, and that of the Notch gene, acting as receptor, are key components in a lateral-inhibition signalling pathway that regulates the detailed patterning of many different tissues in Drosophila. During neurogenesis in particular, neural precursors, by expressing Delta, inhibit neighbouring Notch-expressing cells from becoming committed to a neural fate. Vertebrates are known to have several Notch genes, but their functions are unclear and their ligands hitherto unidentified. Here we identify and describe a chick Delta homologue, C-Delta-1. We show that C-Delta-1 is expressed in prospective neurons during neurogenesis, as new cells are being born and their fates decided. Our data from the chick, combined with parallel evidence from Xenopus, suggest that both the Delta/Notch signalling mechanism and its role in neurogenesis have been conserved in vertebrates.

Clerkship rotation in rural family practice

Every medical student at Memorial University of Newfoundland must do a rotation in rural family practice. This paper describes the organization of this clerkship learning experience and discusses its possible influence upon career choice.

Biopsychosocial changes associated with cessation of cannabis use: a single case study of acute and chronic cognitive effects, withdrawal and treatment

A 35 year old male was cognitively assessed prior to cessation of 18 years of daily cannabis use and monitored for several weeks post cessation. Brain event-related potential (ERP) measures of selective attention reflecting a difficulty in filtering out complex irrelevant information showed no indication of improvement over 6 weeks of abstinence. In contrast, when tested in the acutely intoxicated state prior to cessation of use, a dramatic normalisation of the ERP signature of this individual was observed. A treatment program based on supportive-expressive psychotherapy was administered and depression, anxiety and general psychological health were monitored over the course of withdrawal from cannabis.

Family provision of health and welfare in the mixed economy of care in the late nineteenth and twentieth centuries

The paper begins by discussing the place of the family as a provider of welfare in the context of the changing nature of the 'mixed economy of welfare'. It goes on to explore the nature of social provision by the family at the turn of the century, stressing the way in which the behaviour of people within families was taken as the test of citizenship in an ethical state, and was therefore made the target of volumtary and state intervention. The paper concludes by contrasting this with ideas about family responsibility in the late twentieth century, and the concern to promote family provision as an alternative to state provision.