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Biomedical subjects

N Aston

Publications and source records attributed to N Aston.

5 recordsLinked to original sources
PubMed2004

Forgotten vaginal pessary eroding into rectum.

Vaginal pessaries still have a role in the management of uterine prolapse, particularly in elderly patients. However, they are known to cause serious complications if proper care is not taken. We present a case of a rectovaginal fistula, developing secondary to a forgotten vaginal pessary. The shelf pessary was found to have eroded through into the rectum. A review of the relevant literature was undertaken and complications associated with vaginal pessaries are discussed.

Aged, 80 and over↗
PubMed1996

Retrorsine in breast milk influences copper handling in suckling rat pups.

AIMS: To explore the hypothesis that a second xenobiotic agent is required with excess copper to produce Indian Childhood Cirrhosis, this study investigated the effect of the pyrrolizidine alkaloid retrorsine fed to the mother during the suckling period upon the serial changes in neonatal copper status. METHODS: Female Wistar rats with new-born litters were fed either a control or a retrorsine (50 mg/kg) diet. At 0, 4, 8, 11, 15, 18 and 21 days, pups from each litter were weighed, sacrificed and their livers removed for copper, DNA and metallothionein analysis. Serum samples were assayed for caeruloplasmin oxidase activity and albumin. RESULTS: 1) Higher than adult level of hepatic copper in normal rats which rose post-natally before declining from day 11 after birth, 2) raised hepatic copper concentrations and total copper in the retrorsine group from day 15; levels were higher than adult at birth, 3) reduced serum caeruloplasmin oxidase activity and albumin levels in retrorsine group, but both groups lower than adult, 4) lower hepatic metallothionein levels in retrorsine group, but both groups higher than adult, and 5) reduced liver DNA in the retrorsine group when expressed as total DNA and per gram of tissue. These changes were not secondary to under-nutrition as a small study on under-nourished rat neonates showed that copper handling is not significantly altered when compared to well-nourished rats. CONCLUSIONS: Retrorsine passing to rat neonates via breast milk causes: 1) the accumulation of hepatic copper, 2) impairment of the rise in serum caeruloplasmin, which could indicate a decline in synthesis or failure of copper incorporation into the apo-protein, 3) a decrease in hepatic metallothionein and serum albumin levels, again suggesting diminished protein synthesis, and 4) reduced hepatic DNA indicative of decreased cell number but increased cell size. Accumulation of liver copper but reduction of copper-binding proteins could result in free copper and explain the synergistic hepatotoxicity of copper and retrorsine.

Animals↗
PubMed1994

Alpha 1A-adrenoceptor subtype mediates contraction of the rat urethra.

1. The alpha 1-adrenoceptor-mediated responses of the rat urethra to phenylephrine have been examined in vitro. Phenylephrine caused concentration-dependent contractions of the isolated urethra which were antagonized by WB4101 (3-30 nM) and prazosin (10-100 nM) but not idazoxan (1.5 microM). Schild plot analysis of the antagonism by prazosin and WB4101 yielded straight lines with slopes not significantly different from unity. The pA2 value of 9.0 for WB4101 was significantly greater than the value previously obtained at the alpha 1B-adrenoceptor of the rat spleen. 2. 5-Methylurapidil (30 nM) and abanoquil (1 nM) caused dextral shifts of concentration-response curves yielding pKB values of 8.3 and 9.4 respectively. Maximal responses to phenylephrine were also reduced by this concentration of abanoquil. 3. Preincubation with chloroethylclonidine (25 microM for 40 min) failed to alter responses, but removing extracellular calcium or the presence of nifedipine (1 microM) almost abolished contractions to phenylephrine. 4. These results indicate that the responses of the rat urethra to phenylephrine are mediated via the alpha 1A-adrenoceptor subtype and are dependent on the influx of extracellular calcium.

Aminoquinolines↗