336 TRANSGENIC Stra8-EYFP PIGS: A MODEL FOR DEVELOPING MALE GERM CELL TECHNOLOGIES

Stimulated by retinoic acid 8 (STRA8) is a protein that is required for meiotic initiation in both male and female gametes in vertebrates. It is also expressed in embryonic germ cells and neonatal male germ cells of mice. The utility of using the Stra8 promoter to recognise and isolate pre-meiotic male germ cells has been reported by others in the mouse. In order to mark germ cells in male pigs, we cloned 1.6 kb of the mouse Stra8 promoter and used it to develop a reporter plasmid using mitochondrial-localised enhanced yellow fluorescent protein (mEYFP). The Stra8-mEYFP transgenic male pigs were produced using somatic cell nuclear transfer. The mEYFP reporter was expressed and easily detectable in the live germ cells of the mature animals and could be observed during tissue culture. The mitochondrial-localised expression of the EYFP reporter was helpful in observing the size and stage of the germ cell. The mEYPF protein was found to be expressed only in the testis of the transgenic pigs using Western blot analysis, whereas endogenous STRA8 protein was also detected in the lung and brain. Fluorescent immunohistochemistry of testicular sections of the transgenic pigs indicated a similar expression pattern to that of the endogenous STRA8 protein. There was an overlap in the expression of the mEYFP and the endogenous STRA8 protein; however, it was observed that the mEYFP protein was present at an earlier stage of spermatogenesis than the STRA8 protein. Immunocytochemistry performed on plated tubules similarly showed varying intensity in expression between the mEYFP transgene and the endogenous STRA8. The difference in the timing of protein expression may be due to the model created or the use of the mouse Stra8 promoter for the expression of mEYFP. Alternatively, the lag in expression between that of the endogenous STRA8 and mEYFP protein may be due to attenuated translation of the Stra8 mRNA. This transgenic model should be useful for the study of reproduction, development, transplantation, biotechnology, and culture of the pig male germ line. Supported by North Carolina Agricultural Research Service 02234.

Prolactin and growth hormone receptors

The two hormones prolactin and growth hormone exhibit considerable structural homology as well as exerting similar biological effects, especially the primate hormones. One effect of prolactin that deserves greater attention is its action on the immune system including the stimulation of growth of experimental lymphomas, both in vivo and in vitro. One cultured lymphoma cell line has proved to be a very useful model system in which to examine prolactin receptor synthesis and turnover as well as post-receptor mechanisms of action. Prolactin and growth hormone receptors from rabbit mammary gland and liver respectively have been partially purified and characterized. Polyclonal antibodies to prolactin and growth hormone receptors have been generated. The antibodies have been shown to cross-react with prolactin or growth hormone receptors from a number of species, indicating structural homology among receptors as well as hormones. The polyclonal antisera inhibit the action of prolactin in vivo as well as in vitro. In addition, several of the same antisera also mimic the action of prolactin. As yet the presence of autoantibodies to prolactin or growth hormone receptors in human serum samples has not been recognized.

Effects of light on microalgae concentrations and selenium uptake in bivalves exposed to selenium-amended sediments

The purpose of the current study was to evaluate the role of visible light during trophic transfer of the essential metalloid, selenium (Se) from sediments by way of the microalgae Phaeodactylum tricornutum to bivalves. Initial experiments compared uptake of Se with algal cell number after deposit-feeding (Tellina deltoidalis) and filter-feeding (Soletellina alba) bivalves were exposed for 12 days under 16:8 h light:dark and 24-hour dark regimes to sediments amended with Se (17 mg/kg dry weight). Comparisons of filter-feeding with deposit-feeding organisms indicated >2-fold higher body burdens in the deposit-feeding organisms after 12 days. Darkness failed to significantly and consistently diminish algal cell densities. However, general trends indicated a decrease of pelagic algal numbers in +Se/dark treatments during the 12-day exposure. To determine whether time-dependent patterns were present in the uptake of Se by the deposit-feeding species, a second experiment was conducted using Se-laden sediments under light and dark conditions. Algal cell counts were measured and Se concentrations determined in animals sampled at days 0, 3, 6, 9, and 12. Deposit-feeding animals maintained in the dark accumulated, Se more rapidly than animals on light to dark cycles until 12 days at which time no significant differences were observed between treatments. Concentrations of Se in tissues of deposit-feeding bivalves were not directly related to algal cell density in lighted or dark chambers. These results indicate that pelagic microalgae may only play a key role in Se uptake during early hours of exposure, and feeding behavior may be a more important factor in deposite-feeding bivalves.

Reduced penetrance alleles for Huntington's disease: a multi-centre direct observational study

OBJECTIVE

To obtain penetrance data for Huntington's disease when DNA results are in the range of 36-39 CAG repeats and assess the consistency of reporting the upper allele from two reference centres.

METHOD

Data were collected anonymously on age of onset or age last known to be unaffected from a cohort of individuals with results in this range. DNA samples were re-analysed in two reference centres. Kaplan-Meier analysis was used to construct an age of onset curve and penetrance figures.

RESULTS

Clinical data and concordant DNA results from both reference centres were available for 176 samples; penetrance figures (and 95% confidence intervals) for this cohort, at age 65 and 75 years, were 63.9% (55.5% to 73.2%) and 74.2% (64.2% to 84.2%), respectively. Inclusion of 28 additional subjects for whom repeat DNA results were unavailable, obtained from only one reference centre, or discrepant by one repeat within this range, gave penetrance data (including 95% confidence intervals) at ages 65 and 75 years of 62.4% (54.4% to 70.4%) and 72.7.% (63.3% to 82.1%), respectively. 238 duplicate results were available from the reference centres; 10 (4.2%) differed by one CAG repeat in the reporting of the upper allele and in two (0.84%) of these cases the discrepancy was between 39 and 40 repeats.

CONCLUSION

When DNA results are in this range, a conservative approach is to say that there is at least a 40% chance the person will be asymptomatic at age 65 years and at least a 30% chance the person will be asymptomatic at age 75 years.

Oral or topical nasal steroids for hearing loss associated with otitis media with effusion in children

BACKGROUND

Otitis media with effusion (OME) is common and may cause hearing loss with associated developmental delay. Treatment remains controversial.

OBJECTIVES

To examine evidence for or against treating children with hearing loss associated with OME with systemic or topical intranasal steroids.

SEARCH STRATEGY

We searched the Cochrane Ear, Nose and Throat Disorders Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library Issue 4 2005, MEDLINE (1966 to 2006), EMBASE (1974 to 2006), and the CINAHL, LILACS, Zetoc, IndMED, SAMED, KoreaMed, MEDCARIB and Cambridge Scientific Abstracts databases in January 2006.

SELECTION CRITERIA

Randomised controlled trials of oral and topical intranasal steroids, either alone or in combination with another agent such as an antibiotic, were included.

EXCLUSIONS

publications in abstract form only; uncontrolled, non-randomised or retrospective studies; studies reporting outcomes with ears (rather than children).

DATA COLLECTION AND ANALYSIS

Data were extracted from the published reports by the authors independently using standardised data extraction forms and methods. The methodological quality of the included studies was independently assessed by the authors as described in the Cochrane Handbook. Dichotomous results were expressed as an odds ratio using a fixed-effect model together with the 95% confidence intervals. Continuous data were analysed using the weighted mean difference in a fixed-effect model. Tests for heterogeneity between studies were performed using a Mantel-Haenszel approach. In trials with a cross-over design, post cross-over treatment data were not used.

MAIN RESULTS

No study prospectively documented hearing loss associated with OME prior to randomisation. Follow up was mainly short term. The odds ratio for OME persisting after short-term follow up in children treated with oral steroids compared to control was 0.22 (95% CI 0.08 to 0.63). The odds ratio for OME persisting after short-term follow up for children treated with oral steroids plus antibiotic compared to control plus antibiotic was 0.37 (95% CI 0.25 to 0.56). However, there was significant heterogeneity between studies included in the latter comparison (P < 0.01). Trends favoured steroids for most other comparisons, but confidence intervals included unity. There was no evidence of benefit for steroid treatment for OME or hearing loss associated with OME in the longer term.

AUTHORS' CONCLUSIONS

Both oral and topical intranasal steroids alone or in combination with an antibiotic lead to a quicker resolution of OME in the short term, however, there is no evidence of longer term benefit.