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Biomedical subjects

J Ashmore

Publications and source records attributed to J Ashmore.

At least 19 recordsLinked to original sources
PubMed2000

The cochlea.

Explore the source record for details and available documents.

Adaptation, Physiological↗
PubMed2000

Complex obstetric fistulae--two case reports.

Two cases of complex obstetric fistulae are reported. Poor assessment and mismanagement of labour were revealed. The resulting fistulae were vesico-urethro-rectovaginal and vesico-cervico-vaginal. Plastic repair using a modified Martius graft was used in case 1. Considering the young age of the patient, transplantation of the ureters into the rectum or colon was deemed undesirable. The patient's endurance over a period of ten years, with seventeen attempts at repair ultimately was rewarded by achieving both vesical and rectal continence. Repair using the transvaginal route was successful at the first attempt in case 2.

Adult↗
PubMed1999

The role of observer error in antenatal dipstick proteinuria analysis.

OBJECTIVE: To determine the role of inter-observer error and the influence of training upon dipstick urine analysis. DESIGN: A two phase observational and training study. METHODS: Five standard solutions of serum albumin were used to test the accuracy of midwives and nursing auxiliaries involved in dipstick urine analysis at a maternity hospital. The standard solutions were chosen such that they should have resulted in negative (n = 2) and positive (n = 3) dipstick test results, respectively. SETTING: A teaching maternity hospital and academic department of obstetrics and gynaecology. PARTICIPANTS: Twenty midwives, 20 nursing auxiliaries and nine laboratory technicians. RESULTS: For the two nonproteinuric solutions, a higher false positive rate was observed for nursing auxiliaries (40% and 55%), compared with midwives (5% and 30%) (P = 0.020 and P = 0.20, respectively). Before training, laboratory technicians recorded high false positive rates (67% and 89%), but after training these were reduced to 0% and 22% (P = 0.25 and P = 0.023, respectively). Both nursing auxiliaries and midwives recorded false negative rates of between 10% and 45% for the three proteinuric solutions. CONCLUSIONS: Observer error may be reduced by assigning midwives to urine dipstick analysis or by the implementation of directed training. Classification of pre-eclampsia or other hypertensive diseases of pregnancy on the basis of the presence and degree of proteinuria should be confirmed with a 24-hour quantitative protein collection.

False Negative Reactions↗
PubMed1998

Mechanosensation: swimming round in circles.

Studies of inherited deafness disorders in mice and humans are providing new insights into the basis of hair-cell mechanosensitivity; this enterprise has been joined by large-scale genetic screening in the zebrafish, where a number of intriguing mutants defective in mechanosensation have recently been described.

Animals↗
PubMed1998

Hearing.

The aim of this chapter is to describe some of the features of the processing of the auditory world and how different levels of explanation are appropriate to the understanding of hearing. The working of the inner ear is best seen as a the operation of a purposefully structured machine for the extraction of biologically meaningful components from a sound. Physical scales determine in large part the appropriate description of the auditory system.

Animals↗
PubMed1998

How well do we understand the cochlea?

As sensory cells, hair cells within the mammalian inner ear convert sounds into receptor potentials when their projecting stereocilia are deflected. The organ of Corti of the cochlea contains two types of hair cell, inner and outer hair cells, which differ in function. It has been appreciated for over two decades that although inner hair cells act as the primary receptor cell for the auditory system, the outer hair cells can also act as motor cells. Outer hair cells respond to variation in potential, and change length at rates unequalled by other motile cells. The forces generated by outer hair cells are capable of altering the delicate mechanics of the cochlear partition, increasing hearing sensitivity and frequency selectivity. The discovery of such hair-cell motility has modified the view of the cochlea as a simple frequency analyser into one where it is an active non-linear filter that allows only the prominent features of acoustic signals to be transmitted to the acoustic nerve by the inner hair cells. In this view, such frequency selectivity arises through the suppression of adjacent frequencies, a mechanical effect equivalent to lateral inhibition in neural structures. These processes are explained by the interplay between the hydrodynamic interactions among different parts of the cochlear partition and the effective non-linear behaviour of the cell motor.

Animals↗
PubMed1998

Control of the human cell cycle by a bacterial protein, gapstatin.

The oral gram-negative bacterium Actinobacillus actinomycetemcomitans is a major pathogen in human periodontal disease. Saline extraction releases a range of surface-associated components from this bacterium, including one which exhibits potent anti-proliferative activity as assessed by its capacity to inhibit DNA synthesis by human and other mammalian cells. Cultures incubated with this bacterial fraction for a prolonged period comprise a high proportion of cells containing a 4n level of DNA. Studies using hydroxyurea-synchronized cultures showed that cells treated with the surface-associated fraction were arrested in the G2 phase of the cell cycle and did not enter mitosis. This G2/M blockade was observed only when the bacterial fraction was added to the cells during early S phase. Our data also suggest that the active bacterial component binds to surface receptors expressed by the human cells and may act by a novel mechanism which involves down-regulation of cyclin B1 expression. The anti-proliferative activity of the bacterial fraction, purified by a combination of ammonium sulphate precipitation, HPLC anion exchange and gel filtration, has been shown to be an 8 kDa protein, which we have called gapstatin. Purified gapstatin was shown to be responsible for the the inhibitory effects of the surface-associated fraction on mammalian cells.

Aggregatibacter actinomycetemcomitans↗
PubMed1998

Knowledge of disease and dietary compliance in patients with end-stage renal disease.

Noncompliance is a common problem in patients with end-stage renal disease. In this study, we assessed the relationship between knowledge of disease and dietary compliance in a cohort of 56 dialysis patients. Based on a health belief model of adherence, we predicted that dialysis patients who knew more about kidney disease and its treatment would be more complaint than those who knew less about these matters. We also examined the relationship between dietary compliance and patients' emotional well-being. We used a composite measure of compliance consisting of serum K, P, and interdialytic weight gain. A 30-item "Kidney Disease Questionnaire" was used to assess patients' knowledge of their illness. Contrary to prediction, compliers did not score higher on the knowledge questionnaire; in fact, the observed correlation of .32 was in the opposite direction. In the same vein, we found no relationship between compliance and emotional well-being. These results, although somewhat surprising, add to a growing body of research which indicates that medical compliance involves more than educating patients about the mechanisms and treatment of their illness.

Adult↗
PubMed1998

Massive ascites and bilateral hydrothorax complicating severe pre-eclampsia.

Massive ascites and hydrothorax as additional complications of pre-eclampsia are rare. The case reported is one of ascites and bilateral hydrothorax in a patient with severe pre-eclampsia. Careful antenatal assessment may help in detecting more cases with this complication, which is often misunderstood and the diagnosis missed.

Adult↗
PubMed1995

Hearing. A gene for deaf ears?

Genetic mutations that lead to hearing losses have been identified in both human and mouse populations; the gene products include members of a class of unconventional myosins.

Animals↗
PubMed1991

Regulation of insulin-like growth factor-binding protein-1 synthesis and secretion by progestin and relaxin in long term cultures of human endometrial stromal cells.

The decidualized endometrium during the first trimester of pregnancy synthesizes and secretes a 32-kDa insulin-like growth factor-binding protein (termed hIGFBP-1) at high levels. IGFBP-1 is the major soluble protein product of this tissue and is principally localized to the differentiated endometrial stromal cell, the decidual cell. In the present study long term culture of stromal cells from the nonpregnant endometrium have been employed to elucidate the hormonal requirements for IGFBP-1 production. Immunoreactive IGFBP-1 was undetectable in control cultures. However, inclusion of medroxyprogesterone acetate (MPA) induced rates of 0.35 +/- 0.09 microgram/0.1 mg cell DNA.day (mean +/- SEM; n = 5) after 20-30 days. In these cultures cells exhibited morphological changes consistent with decidual cell differentiation. In all cultures removal of MPA after exposure for 10-16 days, with or without subsequent inclusion of relaxin (RLX), increased production of IGFBP-1 450- to 4600-fold to rates of 150-710 micrograms/0.1 mg cell DNA.day or 26-131 micrograms/10(6) cells.day on days 24-26. The rates tended to be higher with the inclusion of RLX and were sustained in contrast to cultures without RLX, where rates fell by day 30. Individual cultures responded differently to RLX when added from the initiation of culture, with either a response similar to MPA alone or a cyclical change in production, achieving maximal rates of 190-290 micrograms/0.1 mg cell DNA.day. Cultures in which RLX alone induced high IGFBP-1 high production were obtained from endometrium during the progesterone-dominated luteal phase. In cultures exhibiting high rates of immunoreactive IGFBP-1 production, the protein represented their major secretory protein product. This was confirmed by [35S]methionine incorporation and the presence of IGFBP-1 as the predominant protein in serum-free culture medium. The immunoreactive IGFBP-1 isolated from culture medium was found to be identical, by a number of criteria, with IGFBP-1 derived from decidual tissue. These results were consistent with a primary role of progestin exposure, whether in vivo or in vitro, in converting endometrial stromal cells to cells potentially able to exhibit the high rates of IGFBP-1 production typical of the decidualized endometrium of pregnancy.

Adult↗