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Biomedical subjects

E J Williams

Publications and source records attributed to E J Williams.

At least 73 records · Page 4Linked to original sources
PubMed1991

Parasites of domestic and wild animals in South Africa. XXVIII. Helminth and arthropod parasites of Angora goats and kids in Valley Bushveld.

Two adult Angora goats were slaughtered each month for 24 consecutive months on a farm in Valley Bushveld in the eastern Cape Province. On the same farm 2 Angora goat kids were slaughtered each month for 2 consecutive years from the time they were 1 week old until they reached 12 months of age. All these goats were processed for the recovery of helminth and arthropod parasites. Fourteen nematode species, 2 nematode genera and 1 cestode species were recovered. Worm burdens were generally low in the adult goats. Nematode burdens increased erratically in the kids reaching the greatest numbers when they were 1 year old. The tapeworm, Moniezia expansa, was present in kids at 3 or 4 months of age and had usually disappeared by the time they reached 7 months of age.

Animals↗
PubMed1991

Parasites of domestic and wild animals in South Africa. XXV. Ixodid ticks on sheep in the north-eastern Orange Free State and in the eastern Cape Province.

The tick burdens of 115 Merino sheep, slaughtered over a period of 15 consecutive months on a farm in the north-eastern Orange Free State, were determined. A total of 7 ixodid and 1 argasid tick species were recovered and the seasonal abundances of Boophilus decoloratus, Hyalomma marginatum rufipes, Margaropus winthemi and Rhipicephalus evertsi evertsi were determined. One hundred and forty-nine Merino sheep were slaughtered over periods varying from 10 to 25 months on 3 farms in Eastern Province Thornveld in the eastern Cape Province and their tick burdens determined. Fourteen ixodid tick species were recovered from these animals and the seasonal abundances of Amblyomma marmoreum, B. decoloratus, Haemaphysalis silacea, R. evertsi evertsi and Rhipicephalus nitens were ascertained. On a farm in Valley Bushveld in the eastern Cape Province, 2 Dorper sheep were slaughtered each month for a period of 24 consecutive months. These 48 sheep harboured 10 ixodid tick species and the seasonal abundances of A. marmoreum, H. silacea, Rhipicephalus appendiculatus and Rhipicephalus glabroscutatum were determined. A total of 17 ixodid tick species, of which 12 had reached the adult stage, where recovered from the sheep on the 5 farms.

Animals↗
PubMed1991

Parasites of domestic and wild animals in South Africa. XXVI. The mosaic of ixodid tick infestations on birds and mammals in the Mountain Zebra National Park.

Sixteen species of ixodid ticks were collected over varying periods of time from 6 species of ground-frequenting birds and 15 species of small and large mammals in the Mountain Zebra National Park, Karoo, Cape Province. Margaropus winthemi followed by Rhipicephalus glabroscutatum and Rhipicephalus evertsi evertsi were the most abundant species. The host preferences of 14 tick species and the seasonal abundances of 13 species were determined. Small numbers of immature stages of only a few tick species were generally recovered from ground-frequenting birds, mice and rats. Amongst the slightly larger animals the smallest number of ticks and species were recovered from springhares and the largest numbers from scrub hares. Amongst the larger mammals, very few ticks were harboured by springbuck and black wildebeest, while heavy infestations of several species were encountered on Cape mountain zebras and eland.

Animals↗
PubMed1991

Parasites of domestic and wild animals in South Africa. XXVII. Ticks on helmeted guineafowls in the eastern Cape Province and eastern Transvaal Lowveld.

Seventy-six helmeted guineafowls (Numida meleagris) were shot in the Andries Vosloo Kudu Reserve and on an adjacent farm in the eastern Cape Province during the period May 1985 to January 1987 and their tick burdens determined. A total of 10 ixodid tick species were recovered, of which Amblyomma hebraeum, Amblyomma marmoreum and Haemaphysalis silacea were the most abundant. The seasonal abundances of these 3 species and of Hyalomma marginatum rufipes were ascertained. A marked difference between the total number of A. hebraeum recovered from the birds in the reserve and those on the farm is ascribed to the treatment of domestic stock on the farm with an acaricide. The tick burdens of 118 helmeted guineafowls, shot in the southern part of the Kruger National Park, eastern Transvaal Lowveld, from August 1988 to August 1990, were also determined. Ten ixodid tick species and the larvae of an argasid species were recovered. A. hebraeum, A. marmoreum and the Argas sp. were the most abundant and their seasonal abundances and that of Rhipicephalus zambeziensis were determined. Only 2 of the 54,659 ixodid ticks recovered from the birds at the 3 localities were adults and the presence of these is ascribed to accidental infestations.

Animals↗
PubMed1990

Helminth and arthropod parasites of Angora goats on irrigated Kikuyu grass pastures in the eastern Cape Province.

Angora goat kids and yearlings grazing irrigated Kikuyu (Pennisetum clandestinum) grass pastures in the eastern Cape Province, became heavily infected with Teladorsagia circumcincta and Trichostrongylus rugatus, leading to high mortality in both age groups. Peak burdens of the former were recorded during March and May, and of the latter during May and June. Larger numbers of the cestode Moniezia expanza, occurred in the kids than in the yearlings. Despite the stress of high helminth burdens, no clinical cases of coccidiosis were seen. Both groups of goats were infested with small numbers of immature stages of the tortoise tick, Amblyomma marmoreum, and the yellow dog tick, Haemaphysalis leachi. Infestation with the biting louse, Damalinia limbata, occurred within 2 d of birth, but never reached very large numbers. Larvae of the nasal botfly, Oestrus ovis, were present only from January to July.

Animals↗
PubMed1989

Preferential induction of the rat hepatic P450 I proteins by the food carcinogen 2-amino-3-methyl-imidazo[4,5-f]quinoline.

1. Administration of the food carcinogen, 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ) to rats gave rise to significant dose-dependent increases in the microsomal O-deethylations of ethoxycoumarin and ethoxyresorufin but had no effect on the O-dealkylation of pentoxyresorufin and the NADPH-dependent reduction of cytochrome c, and decreased the N-demethylation of dimethylnitrosamine. Microsomal cytochrome b5 and total cytochrome P-450 levels decreased following the administration of the carcinogen. 2. Hepatic microsomal preparations from IQ-treated animals were much more efficient than control in activating the premutagen 2-amino-6-methyldipyrido[1,2-a:3',2'-d]imidazole to mutagenic intermediates in the Ames test. 3. Immunoquantification of two of the major families of cytochrome P-450, namely P450 I and P450 II B, using ELISA techniques showed that treatment with IQ induced the apoprotein levels of the P450 I family but not of P450 II B. 4. Immunoblot analysis employing polyclonal antibodies against P450 I revealed that IQ induced both isoenzymes of this family, namely P450 I A1 and A2. 5. It is concluded that IQ is an inducer of the rat hepatic monooxygenases, selectively inducing the P450 I family as predicted by a computer-graphic analysis of its dimensions which showed that it is a large, essentially planar, molecule.

Animals↗
PubMed1989

The food pyrolysis product IQ enhances its own activation.

The metabolic activation of the food pyrolysis product 2-amino-3-methylimidazo (4,5-f) quinoline (IQ) to mutagenic intermediates in the Ames test was studied using hepatic activation systems from control and IQ-treated rats. Hepatic S9 preparations from IQ-treated rats were more efficient than control in converting IQ to mutagens. An increase was also seen when isolated microsomes were employed as activation systems but this was less pronounced. The microsome-mediated mutagenicity of IQ was potentiated by addition of the cytosolic fraction from control and IQ-treated rats, the latter being more effective. It is concluded that IQ, at the doses employed in the present study, enhances its own bioactivation to genotoxic metabolites by stimulating both its microsomal and cytosolic metabolism.

Animals↗
PubMed1986

A homogeneous assay for biotin based on chemiluminescence energy transfer.

Chemiluminescence energy transfer between aminobutylethylisoluminol (ABEI)-biotin and fluorescein-avidin was investigated in order to establish a homogeneous assay for serum biotin in the physiological range. ABEI chemiluminescence was measured at pH 7.4 using microperoxidase-hydrogen peroxide and the chemiluminescence at two wavelengths (460 and 525 nm) measured simultaneously to quantify chemiluminescence energy transfer. ABEI-biotin was synthesized by a mixed anhydride reaction and purified by TLC and HPLC. Binding of ABEI-biotin to fluorescein-avidin resulted in a quenching of the chemiluminescence. Chemiluminescence energy transfer was demonstrated by a 2.5-fold decrease in the ratio of blue (460 nm) to green (525 nm) light emission compared with unbound ABEI-biotin. This energy transfer was used to establish an assay for biotin in the range 1 to 10 nM by relating the concentration of biotin to the ratio of chemiluminescence monitored at 460 and 525 nm simultaneously. The assay was capable of detecting biotin in reference sera and in patients with malabsorption syndromes and chronic alcoholism. The reference range in normal subjects was 1.2 to 4.3 nmol/liter mean +/- SD = 2.41 +/- 0.91 nmol/liter (n = 20). The quenching of the chemiluminescence of ABEI-biotin when bound to fluorescein-avidin appeared to be the result of a direct interaction between the excited state product of ABEI and fluorescein.

Avidin↗
PubMed1986

Parasites of domestic and wild animals in South Africa. XVIII. The crowned guinea fowl (Numida meleagris), an important host of immature ixodid ticks.

The tick burdens of 10 crowned guinea fowl (Numida meleagris), shot at approximately 3-monthly intervals in the Mountain Zebra National Park, and of 21 crowned guinea fowl from the Andries Vosloo Kudu Reserve, the majority of which were shot at monthly intervals, were determined. No adult ticks were recovered from any of the guinea fowl. The birds in the Mountain Zebra National Park harboured 4 species of ixodid ticks of which Amblyomma marmoreum was the most abundant and most prevalent. Three birds also harboured Hyalomma marginatum turanicum. Six ixodid tick species were present on guinea fowl in the Andries Vosloo Kudu Reserve. Of these Amblyomma hebraeum was the most abundant and all the birds were infested. Most of these birds were also infested with A. marmoreum and Haemaphysalis silacea and some harboured Hyalomma marginatum rufipes. The seasonal abundance of ticks on crowned guinea fowl is discussed.

Animals↗
PubMed1985

The variation of finger tremor with age in man.

The variation of the amplitude and frequency of finger tremor was studied in 190 subjects ranging in age from 7 to 77 years. Tremor was measured in various postures with an accelerometer and a transduced signal was analysed by Fourier analysis. The variation of tremor frequency and amplitude with age depended upon the posture adopted for measurement and in certain postures some of the variation was related to changes in stature with age.

Adolescent↗
PubMed1984

Chromatographic analysis of organic compounds in the atmosphere.

Fused silica capillary columns with thick films of cross-linked coatings have been used to separate many of the organic compounds that are present in the volatile fraction of automobile exhaust and in ambient air. Techniques have been developed that allow reversible collection and pre-concentration of organic compounds in ambient air on polymeric sorbents with minimal artifacts. The exhaust samples, which are directly injected without pre-concentration on sorbents, contain many of the same organic compounds that are found in sorbent-collected samples of urban ambient air. Similar anthropogenic organic compounds are not, in general, detected (less than 0.02 ppbV) in air samples from remote, rural areas in Colorado.

Air↗
PubMed1984

Effect on finger tremor of withdrawal of long-term treatment with propranolol or atenolol.

The effect of the withdrawal of long-term beta-adrenoceptor blockade on pulse rate and finger tremor was studied in 27 patients who had been treated for 2 years following an uncomplicated myocardial infarction with either atenolol, propranolol or placebo. During treatment, pulse rate was significantly lower in patients treated with propranolol or atenolol compared with placebo. Compared with the response in the placebo group the mean increase in tremor on withdrawal of propranolol was statistically significant for postural and for work tremor in both hands. A significant increase in tremor on withdrawal of atenolol occurred only in the postural position and in a narrow frequency band (left hand, 7-11 Hz; right hand, 7-9 Hz). The differences in the effect on tremor of withdrawal of treatment with propranolol or atenolol in doses which produced similar reductions in heart rate, emphasise the beta 2 classification of peripheral receptors associated with normal muscle tremor but do not exclude the involvement of beta 1-adrenoceptors.

Atenolol↗
PubMed1981

Digital plethysmography for assessing erythrityl tetranitrate bioavailability.

The bioavailability or oral, sublingual, and chewable tablets or erythrityl tetranitrate (ETN) was evaluated in 15 normal men. In a randomized, complete crossover investigation with nitroglycerin and placebo controls, drug-induced changes in the diastolic amplitude response intensity were measured with a digital plethysmogram. Values for area under the response intensity curve (AUC), maximum response intensity (Imax), and time lapse from dosing to peak response (tmax) were obtained by computer processing and converted to intensity values and AUC segments for specific time intervals. Sublingual nitroglycerin induced a response (p less than 0.05) from placebo within the first hour. Although somewhat slower in reaching peak intensity, all forms of ETN induced significant responses over placebo (p less than 0.05) for 2 hr, with oral (swallowed) ETN different 6 hr. Our results indicate that all the ETN dosage forms were bioavailable, with the longest duration of effect by the oral form.

Administration, Oral↗