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Biomedical subjects

R Snowden

Publications and source records attributed to R Snowden.

At least 37 records · Page 2Linked to original sources
PubMed1982

Isotoxic oral and inhalation exposure of carbon tetrachloride in Porton-Wistar and Fischer rats.

Male Fischer or Porton-Wistar rats were exposed for 4 h to different atmospheric concentrations of CCl4 or were given increasing oral doses, of CCl4 in order to estimate isotoxic exposures or doses. Animals were killed 20 h after treatment, their serum glutamic-pyruvic transaminase activities were measured and their livers were processed for histological examination. It has been found that the equitoxic oral dose in Wistars is 1.5 times that in Fischer rats and more than 3 times after inhalation. Therefore, the conversion factors from inhalation exposure to oral dose were much higher for Fischer than for Porton-Wistar rats. After oral dosing, the extent of centrilobular damage in Fischer rats was approximately twice that in Porton-Wistar rats. After inhalation exposure, the extent of damage was the same in the two strains, but at least at the two lower exposure levels hydropic degeneration definitely contributed to the size of the damaged areas more in Porton-Wistar than in Fischer rats.

Administration, Oral↗
PubMed1982

The comparative renotoxicology of phenylmercury and mercuric chloride.

The acute renotoxicity of HgCl2 and phenylmercuric acetate (PhHgAc) was compared at two intraperitoneal dose levels: 0.5 and 1.0 mg Hg/kg. There was no difference in the type of proximal tubular damage caused by the two mercurials, but 1.0 mg Hg/kg as PhHgAc produced approximately the same degree of damage as 0.5 mg Hg/kg as HgCl2. At the selected dose levels only HgCl2, but not PhHgAc increased the urinary excretion of alkaline phosphatase. At 12 and 24 h after PhHgAc the content of mercury was higher in blood and lower in the kidneys and urine than after the administration of equimolar doses of HgCl2. As the difference in the rectal mercury contents of HgCl2 and PhHgAc treated groups declined with time, difference in renotoxicity seems to relate only to renal mercury taken up within 24 h of administration. It is suggested that the slower renal extraction of mercury - as in regenerating kidneys (Tandon and Magos 1980) - was responsible for the lower degree of renotoxicity in phenylmercury treated rats.

Alkaline Phosphatase↗
PubMed1982

General assessment of the Multiload Cu250 intrauterine device. UK network of IUCD research clinics.

A total of 803 fittings of the Multiload Cu250 were undertaken between May and December 1979 in the UK IUCD network co-ordinated by the Institute of Population Studies. University of Exeter. Each woman fitted with the device was followed in a prospective study until a pregnancy, expulsion or removal occurred or the woman was released from follow-up after 2 years of continuous use. Because of the large number of fittings undertaken it is possible to compare the experience of groups of women determined by a number of criteria. The most useful distinction was between those of differing parity. Comparisons have been made between nulliparous women, women of low parity (1 or 2) and those of high parity (greater than or equal to 3). By concentrating on the characteristics of the woman receiving the IUCD it is possible to provide those responsible for fitting IUCDs with information that will have predictive value in relation to specific categories of women. The results of the study show that, despite some variation between women of different parity, the Multiload Cu250 is comparable with other IUCDs currently available in the UK in terms of the relative risks of pregnancy and removal of the device after a complaint of bleeding or pain. The removal rate is biased towards complaints of pain among nulliparous women which is also reported to be present at the times of IUCD fitting and removal. As expected with a device of this configuration, the expulsion rate is low when compared with other devices. Once into the uterus this device appears to be an effective contraceptive but fittings in nulliparous women more frequently necessitate dilatation of the cervix and this is associated with more frequent reports of difficulty at fitting and complaints of pain.

Female↗
PubMed1979

The effects of bromosulphophthalein, indocyanine green and bilirubin on the biliary excretion of methylmercury.

The effects of three ligands for ligandin on the biliary excretion of methylmercury were investigated in male rats injected intravenously with 1.0 mg/kg Hg as Me203 HgCl. Bromosulphophthalein and indocyanine green inhibited the biliary excretion of methylmercury, while bilirubin had no such effect. None of the compounds tested which inhibited the biliary excretion of methylmercury decreased bile flow or changed the hepatic concentration of mercury of non-protein thiols. The possibility of the involvement of ligandin in the biliary excretion of methylmercury is discussed.

Animals↗
PubMed1978

The hepatotoxicity of 3-amino-1,2,4-triazole and carbon disulphide in phenobarbitone-treated starved rats.

In phenobarbitone-treated starved male rats 1 g/kg 3-amino-1,2,4-triazole produced moderate liver necorsis and increased the serum glutamic-pyruvic transaminase activity. If half an hour after the administration of aminotriazole animals were exposed for 4 h to 2.0 mg/l CS2, the necrotic damage in the liver was larger and the serum glutamic-pyruvic transaminase activity higher than in rats not exposed to CS2. Carbon-disulphide in phenobarbitone-treated starved male rats caused only a very slight increase in the serum transminase activity in spite of the widespread hydropic degeneration in the liver. These experiments indicated that increase in serum transaminase activity is the consequence of necrosis and not hydropic degeneration; aminotriazole is hepatotoxic in rats when microsomal enzymes are induced and the hepatotoxicity of aminotriazole and carbon disulphide is potentiated by the administration of the other compound.

Alanine Transaminase↗
PubMed1975

Comparison of use of the Dalkon Shield in Dublin and Southampton.

The results of fitting Dalkon Shield I.U.D.s in Southampton and Dublin were compared. At 12 months the continuation rates were 77.4% and 93.4% respectively. There were also differences between the two cities in the major complication rates associated with the use of the device. At 12 months these rates for Southampton and Dublin were: pregnancy 5.6% and 1.4%, expulsion 4.0% and 0.9%, and removal for pain and/or bleeding 12.1% and 3.0%, respectively. Possible reasons for the difference in performance may include the older average age of the users in Dublin, and the greater number and more varied experience of the medical staff responsible for fitting in Southampton. We recommend that population factors be taken into account when comparing data relating to fertility regulation.

Adult↗