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Biomedical subjects

L Jenkin

Publications and source records attributed to L Jenkin.

5 recordsLinked to original sources
PubMed1995

Paradigm: towards an integrated platform for registration of patients in clinical trials.

A generalised registration-randomisation package, known as paradigm, has been developed by the Netherlands Cancer Institute and the MRC Cancer Trials Office initiated in association with the EORTC within the EuroCODE project and partially funded by the European Community. This randomisation software takes into account requirements of four major data centres in Belgium, France, The Netherlands and the UK and is suitable for use at further European Clinical Trial data centres to enable remote entry of patients into trials. The system became operational at the start of 1994, and is now in use at three hospitals and data centres.

Data Interpretation, Statistical↗
PubMed1995

Oxytocin and prostatic function.

It is now well established that oxytocin is present in the mammalian testis and there is growing evidence that the peptide plays a role in the male reproductive tract by both assisting sperm transport and modulating steroidogenesis. In the testis, oxytocin has been shown not only to modulate testosterone production but also to increase the activity of the enzyme 5 alpha-reductase which converts testosterone to dihydrotestosterone (DHT). The prostate is an androgen-dependent organ with DHT being the active steroid. Oxytocin is present in the mammalian prostate. We have shown in the rat that levels of the peptide can be regulated by androgens, prostatic oxytocin concentrations being decreased by testosterone and increased following castration or treatment with an antiandrogen. Oxytocin treatment increases 5 alpha-reductase activity in the prostate of healthy young rats but, unlike the testis, this rise in enzyme activity is only transient. We thus propose that a local feedback mechanism may act to control prostatic levels of DHT and hence prostatic growth. Benign prostatic hyperplasia (BPH) is a common disease which affects both men and dogs. The aetiology of the disease is complex but both DHT and aging are important factors. Oxytocin levels are raised in prostatic tissue from dogs with BPH and the increase in peptide is accompanied by increased 5 alpha-reductase activity. Preliminary findings also suggest that prostatic oxytocin levels are raised in tissue from men with BPH. These data lead us to suggest that oxytocin may be involved in the pathophysiology of the prostate gland.

Aging↗
PubMed1983

A preliminary evaluation of the use of an automatic impedance tympanometer in the diagnosis of otitis media with effusion in children: a report from the Dunedin Multidisciplinary Health and Development Research Unit.

Microscopic examination by two trained examiners, conventional impedance tympanometry by a trained audiometrist, automatic impedance tympanometry by a person with minimal training and puretone audiometry by trained audiometrists were compared in 468 ears, studied blind. There was complete examiner agreement in microscopic examination in 465 (99.3%) ears, minor disagreement in three (0.7%) ears. There was a more complex relationship between examination methods, with microscopic evidence of effusion being present in 88.2% of ears showing B tympanograms to conventional tympanometry and in 66.7% of ears to automatic tympanometry. Automatic tympanometry provides a reasonably accurate method of detecting middle ear effusion, but tends to overdiagnose this condition compared to alternate methods.

Acoustic Impedance Tests↗
PubMedDate not supplied

Evidence for the regulation of prostatic oxytocin by gonadal steroids in the rat.

Oxytocin and its receptor are present in the mammalian prostate, and the peptide has been shown to increase prostatic growth, 5alpha-reductase activity, and contractility. This study was performed to investigate whether local concentrations of the peptide were regulated by gonadal steroids in order to establish whether oxytocin has a physiological role in the prostate. Both intact and castrated adult Wistar rats were treated daily for 7 days with either testosterone propionate or the antiandrogen cyproterone acetate. Animals were then killed, and plasma hormone and prostatic oxytocin concentrations were measured. A separate group of rats was treated with the 5alpha-reductase inhibitor finasteride to investigate whether testosterone or dihydrotestosterone (DHT) was involved in regulating oxytocin concentrations. In a further series of experiments, rats were treated with diethylstilbestrol (DES) or the antiestrogen tamoxifen. Treatment with testosterone significantly decreased prostatic oxytocin, whereas reduction of androgens by castration or by administration of cyproterone acetate increased prostatic peptide concentrations without altering circulating levels of the peptide. Treatment with finasteride increased plasma testosterone but decreased DHT concentrations. Prostatic oxytocin concentrations were higher in finasteride-treated animals than in control animals with comparable testosterone levels. The data suggest that both testosterone and DHT are capable of decreasing prostatic oxytocin concentrations. Treatment with DES did not significantly alter prostatic oxytocin, but administration of tamoxifen decreased concentrations of the peptide, suggesting that low levels of estrogen may be necessary for oxytocin production. These data provide evidence that oxytocin is regulated by androgens, and we hypothesize that this regulatory mechanism may be involved in controlling prostatic growth.

5-alpha Reductase Inhibitors↗