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Biomedical subjects

D E Noakes

Publications and source records attributed to D E Noakes.

At least 55 records · Page 3Linked to original sources
PubMed1991

Bacterial flora of the uterus of cows after calving on two hygienically contrasting farms.

Intrauterine swabs were obtained from cows after calving on two commercial dairy herds with contrasting hygienic environments and incidence of leucorrhea, and cultured aerobically and anaerobically. Of 26 cows with a normal calving and puerperium, eight of 14 (57 per cent) were sterile on farm B where hygiene was poor, compared with five of 12 (42 per cent) on farm A where hygiene was better. Two cows on farm B retained their placentas and subsequently developed metritis/endometritis. Actinomyces pyogenes was the commonest bacterial isolate and Fusobacterium nucleatum, Proteus mirabilis and Bacteroides melaninogenicus were also frequently observed. Similar isolates were obtained from cows on farm B with parturient or puerperal disorders. The contrasting hygienic environments had no influence on either the quantitative or qualitative uterine bacterial flora. Thus, the difference in the incidence of endometritis must have been due to factors other than hygiene.

Actinomyces↗
PubMed1991

Apparent decline in fertility in heifers after repeated oestrus synchronisation with cloprostenol.

Over several years groups of heifers which were repeatedly treated with the PGF2 alpha analogue, cloprostenol, to synchronise oestrus were artificially inseminated. When sperm treatment was optimised, a reduction in conception rate was observed which was related to the number of synchronisation treatments the animals had received. Although factors such as a seasonal reduction in fertility may have contributed to the effect, there appeared to be a decrease in the proportion of animals becoming pregnant after successive synchronisations. Possible explanations for this observation are suggested.

Animals↗
PubMed1990

Use of a uterine pessary to prevent infection of the uterus of the cow after parturition.

A uterine pessary containing penicillin, streptomycin, formosulphathiazole and ethinyloestradiol, was assessed for its efficacy in reducing the frequency and severity of uterine infections in cows after parturition. Fifteen pluriparous Holstein Friesian cows had pessaries inserted into the uterus within 24 hours after calving. Compared with 14 similar untreated cows there were significant reductions in the number infected by Actinomyces pyogenes and in the number exhibiting abnormal uterine discharges.

Animals↗
PubMed1990

Experimental observations on the pathogenesis of necrobacillosis.

Earlier studies showed that the minimum infective dose (greater than 10(6) organisms) of a virulent strain of Fusobacterium necrophorum could be greatly reduced by suspending the fusobacteria in sub-lethal doses of cultures of other bacteria such as Escherichia coli before inoculating mice subcutaneously. In the present study the infective dose of the same strain of F. necrophorum was reduced by a factor of greater than 10(3) by suspending the fusobacteria in sub-lethal doses of 5% homogenate of gaur or wallaby faeces. Sterile faecal filtrate had no such effect. The sites of low grade infection produced by the prior subcutaneous injection of E. coli culture or gaur faecal suspension were susceptible to superinfection by doses of F. necrophorum far below those required to infect normal tissue. This work helps to explain the production of necrobacillosis by the faecal contamination of small wounds. It proved impossible, however, to produce necrobacillosis in mice by the subcutaneous injection of faecal suspensions from 33 farm cattle. This suggests that the proportion of cattle with virulent F. necrophorum in their faeces is low.

Animals↗
PubMed1989

Enhancement of the infectivity of Fusobacterium necrophorum by other bacteria.

Necrobacillosis is caused by Fusobacterium necrophorum (FN), but other organisms are often present in the lesions. Their possible role was studied in experiments made with a virulent FN strain which, by itself, produced fatal necrobacillosis in mice provided that large doses (greater than 10(6) organisms, subcutaneously) were given. Mice were inoculated subcutaneously with FN suspended in sub-lethal doses (0.1 ml) of undiluted or diluted broth cultures of other bacteria. Undiluted culture of a strain of Escherichia coli reduced the infective dose of FN to less than 10 organisms; in the necrobacillosis lesions that developed, fusobacteria greatly outnumbered E. coli. A heat-killed preparation or sterile filtrate of E. coli culture had little if any effect on FN. Citrobacter freundii and comparatively small numbers of Corynebacterium (Actinomyces) pyogenes produced effects similar to that of E. coli. An alpha-haemolytic streptococcus, Pseudomonas aeruginosa, Bacteroides fragilis and Fusobacterium nucleatum also enhanced the infectivity of FN, though less strikingly than E. coli. FN increased the persistence in vivo of the alpha-haemolytic streptococcus and B. fragilis, and enabled the latter to multiply profusely.

Animals↗
PubMed1988

Sexing of sperm by flow cytometry.

Economics dictate that livestock producers will be under increasing pressure to optimise output. A technique for sex pre-selection could help by reducing the number of females required to produce a given number of progeny of the desired sex; the technique would be particularly useful to the dairy industry. Live mammalian sperm, stained with a vital dye and analysed by flow cytometry, show a bimodal fluorescence distribution. Such bimodality may represent two overlapping subpopulations of X- and Y-chromosome bearing sperm. To test this hypothesis, sperm from the two subpopulations were separated using the sorting capacity of a flow cytometer and were used for the insemination of suitably prepared females. The sex of the resulting progeny was determined either by anatomical criteria or by identification of the sex chromosomes by karyotyping. Insufficient data are available so far to provide statistically significant evidence in support of the hypothesis, but a preliminary sequential analysis indicates a progressive tendency towards significance.

Animals↗
PubMed1985

Uterine tube abnormalities as a cause of bovine infertility.

A total of 2000 bovine reproductive tracts (1000 parous and 1000 nulliparous) from freshly slaughtered animals were examined for uterine tube abnormalities and lesions. Tubal lesions were recorded in 180 tracts (9.0 per cent). More parous tracts (6.4 per cent) had tubal lesions than nulliparous tracts (2.6 per cent). The most frequently identified lesion was ovarobursal adhesions which comprised 80 per cent of all abnormalities and were identified in 6.85 per cent of all the genital tracts examined. The uterine tubes were insufflated with carbon dioxide gas to a maximum pressure of 300 mm Hg; 22 were found to be occluded even though they were macroscopically normal.

Animals↗
PubMed1985

Effect of oestrogen and progesterone on sodium, potassium and water balance in sheep.

The effects of oestrogen and progesterone, injected alone or during successive periods, were studied in mature ovariectomised ewes on sodium intakes ranging from 1 to 4 mmol kg-1 d-1. Progesterone had no effect on fluid and electrolyte balance. Oestrogen (17 beta oestradiol) inhibited drinking but had little effect on water excretion whereas it reduced both food intake and urinary potassium concentration. Since the resulting changes in potassium intake and excretion were very similar, oestrogen had little net effect on potassium balance; neither change lasted beyond the treatment period. Oestrogen had a biphasic effect on urinary and faecal sodium excretion, an initial enhancement of salt loss being followed by sodium retention. Faecal sodium retention and the biphasic effect on renal sodium excretion were independent of changes in food intake. These observations are discussed in relation to the pattern of change of electrolyte balance during the reproductive cycle and the influence of changes in food intake and factors affecting sodium preference. The fact that a variety of responses is involved in a coordinated change of sodium balance is emphasised and its possible importance is considered.

Animals↗
PubMed1984

Persistent vaginal haemorrhage in five mares caused by varicose veins of the vaginal wall.

Persistent bleeding from the vulva was the only presenting clinical sign in five non-pregnant pluriparous mares varying in age from eight to 20 years. These were two hunter types, one shire, one thoroughbred and one Arab pony. The haemorrhage originated from ulcerated varicose veins present on the dorsal wall of the vagina adjacent to the vestibulovaginal junction. All five mares were successfully treated, by submucosal resection (two), ligation of vessels (two) or diathermy (one). In four mares there was evidence of vulval incompetence caused by depression of the perineum. The importance of this and the role of impaired venous return during and after pregnancy are discussed.

Animals↗