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Biomedical subjects

J E Cox

Publications and source records attributed to J E Cox.

At least 55 records · Page 3Linked to original sources
PubMed1988

Ventromedial hypothalamic and paraventricular nucleus lesions damage a common system to produce hyperphagia.

We investigated the anatomical basis of paraventricular (PVN) and ventromedial (VMH) hypothalamic hyperphagia. Asymmetrical electrolytic lesions, damaging the VMH and PVN contralaterally, produced significant hyperphagia and weight gains (mean = 257.2 g) almost three times those of controls (89.8 g) during 56 postsurgical days. Weight gain in these rats was not significantly different from that in rats with bilateral lesions of the VMH (277.2 g) or PVN (188.2 g). Combined bilateral destruction of the PVN and VMH produced weight gain (272.8 g) almost identical to that seen after bilateral VMH lesions alone. The lack of additivity of these combined lesions and the effectiveness of the asymmetrical lesions are consistent with the hypothesis that lesions of either of these two regions damage a longitudinally running system to produce elevated food intake and body weight. Cell bodies of this system may lie within the PVN and send efferent projections through the VMH. Hyperinsulinemia developed only in rats with bilateral damage in the VMH. Thus, hypothalamic hyperphagia and hyperinsulinemia appear to be dissociable, reflecting damage to separate neural systems.

Animals↗
PubMed1988

The effect of artificial photoperiod at the end of the breeding season on plasma testosterone concentrations in stallions.

Testosterone concentrations in stallions showed a seasonal trend with peak concentrations in the spring (April and May in Britain) and lowest concentrations in the period from December to February. The effect on this pattern of changing the length of the photoperiod at the end of the normal breeding season (mid-summer's day) was studied in 2 experiments. In the first experiment artificial illumination was organised from 21 June to mimic the effect of transfer to a southern hemisphere spring and summer, that is short days becoming longer. The stallions had low concentrations of testosterone in February and high concentrations in April. Concentrations in July, August and September were extremely low with a return to high values in late November/early December. In the second experiment, illumination was maintained at the equivalent of a 16 1/2-hour day from 21 June to mid December. These stallions had high testosterone concentrations in April, after which they fell until August, later rising to a maximum in October. These results are discussed in relation to transfer of stallions between the northern and southern hemispheres.

Animals↗
PubMed1987

Effect of the surface geometry of smooth and porous-coated titanium alloy on the orientation of fibroblasts in vitro.

The migration and orientation of human gingival fibroblasts in relation to the rim of smooth-surfaced and porous-coated titanium discs placed on multilayers in vitro was investigated. Samples were examined after 6 h, 24 h, 3 days, and 7 days of culture using phase-contrast and scanning electron microscopy. The cells migrated from the multilayer onto the smooth-surfaced discs forming bridges between them, and orientated along parallel circumferential grooves in the rim of the discs. This resulted in the cellular bridges orientating at an acute angle to the rim of the disc, and adjacent cells in the multilayer orientating parallel to the rim. Cellular bridges were also formed between the porous-coated discs and the multilayer but, because the cells that migrated onto, and between, the spheres of the porous-coat showed no preferred orientation, the bridges retained their orientation at right angles to the surface of the rim. This in turn resulted in the cells of the adjacent multilayer becoming similarly orientated. These observations suggest that the geometrical configuration of the surface of implants could influence whether a capsule or an orientated fibrous attachment is developed in relation to implants in vivo.

Alloys↗
PubMed1987

In-vitro biosynthesis of C18 neutral steroids in horse testes.

Deuterium, 14C- and 3H-labelled steroid substrates were incubated with minced testicular tissue from stallions of different ages. After extraction and separation of the neutral and phenolic fractions the metabolites were identified by gas chromatography-mass spectrometry. The presence of the expected C19 neutral and C18 phenolic steroids was confirmed. An isomer of 5(10)-oestrene-3,17-diol was also identified.

Androstenediols↗
PubMed1986

Motor vehicle accidents in northeastern Ontario: are preadmission deaths inevitable?

A large proportion of deaths associated with motor vehicle accidents occur before the victim arrives at hospital. To determine whether these deaths are inevitable, we reviewed the autopsy records of 279 such patients in the Sudbury, Ont., region. The score on the abbreviated injury scale (1980 revision) was calculated for each case; 160 patients had a score of 6 (single fatal injuries) and were excluded from the study. The remaining 119 patients were considered to have had some potential for survival. The main injuries contributing to death were hemorrhage, airway dysfunction, pulmonary contusions and head injuries. Of the 119, 60 had evidence of central nervous system (CNS) injury. The mean injury severity scores (ISSs) for those with and without CNS injury were 37.3 and 33.3 respectively. Of the 64 patients with an ISS of 40 or less, 52 were judged to have had a likelihood of survival if improved trauma care before admission to hospital had been available in the Sudbury region.

Accidents, Traffic↗
PubMed1986

Behaviour of the false rig: causes and treatments.

The false rig is a castrated horse which shows masculine behaviour of one sort or another. The behaviour patterns reported to the author by owners of such animals and the possible causes are discussed here. Some such horses can show all the behaviour patterns of the entire, including erection and intromission. Evidence is presented that the behaviour is not hormonally induced or hormone dependent. The thesis is put forward that the behaviour shown is part of the normal social interaction between horses and possible treatments are discussed in the light of this possibility.

Aggression↗
PubMed1986

Cholecystokinin interacts with prefeeding to impair runway performance.

Previous experiments demonstrated the ineffectiveness of the C-terminal octapeptide of cholecystokinin (CCK-8) for impairing runway performance by food-deprived rats. These results were consistent with the proposal that CCK-8 does not reduce food intake by inhibiting appetitive motivation but instead acts late in the meal to prematurely trigger satiety. For further evaluation of this hypothesis, the effect of CCK-8 on runway performance was assessed after 21 h food-deprived rats consumed a partial meal of 30% sucrose. Injection of 1.0 micrograms/kg CCK-8 after rats were allowed 3 min (6.2 ml consumed) or 5 min (9.7 ml) access to 30% sucrose produced significant reductions in running speed of 43% and 70%, respectively. After 5 min prefeeding, 0.25 and 0.50 micrograms/kg CCK-8 also produced significant decreases in speed of 20% and 59%, respectively. By contrast, CCK-8 had little or no effect without prefeeding. Doses of 0.25 and 0.50 micrograms/kg failed to affect running speed on these tests and 1.0 micrograms/kg produced a small (7%) though significant decrease. These results suggest that inhibition of feeding motivation after CCK-8 administration develops during the course of the meal through interaction with signals generated by the ingestion of food.

Animals↗
PubMed1986

Sham feeding in rats after ventromedial hypothalamic lesions and vagotomy.

Sham feeding was examined in female rats with ventromedial hypothalamic (VMH) lesions with or without abdominal vagotomy. In Experiment 1, intact rats consumed more than twice as much sweet milk during 1-hr tests of sham feeding (M = 13.0 ml) as they did when feeding normally (M = 5.5 ml). Rats with VMH lesions showed exaggerated sham feeding, which was elevated almost fourfold (M = 56.6 ml) over their already high normal feeding baseline (M = 15.1 ml). In Experiment 2, vagotomy substantially reduced sham feeding in rats with VMH lesions. After vagotomy, VMH rats sham fed half as much (M = 23.7 ml) as nonvagotomized VMH rats did (M = 46.8 ml). Vagotomy did not, however, reduce sham feeding to control levels (M = 13.1 ml). These results are consistent with the hypothesis that VMH hyperphagia arises from exaggeration of orosensory responsiveness, which is, in part, a consequence of perturbed vagal function.

Animals↗
PubMed1986

Comparison of the measurement of plasma testosterone and plasma oestrogens for the diagnosis of cryptorchidism in the horse.

The results of performing 1720 blood tests for equine cryptorchidism are described. Using the paired sample human chorionic gonadotrophin (hCG) stimulation test and measuring testosterone, 6.7 per cent of tests did not give a clear result. If only the testosterone concentration in the pre-hCG blood sample was used, this percentage rose to 14 per cent. The paired sample hCG stimulation test was 94.6 per cent accurate. A comparison was made between the paired hCG stimulation test and the measurement of conjugated oestrogen in a single sample. The latter did not give as many doubtfuls but gave false negatives in donkeys of all ages and in horses less than three years old. Measurement of conjugated oestrogen was found to be 96 per cent accurate when donkeys and young horses were excluded. It is, therefore, recommended as a simpler and more reliable test than the paired sample hCG test, but only in the older horse.

Animals↗
PubMed1986

Dietary obesity: brown fat denervation fails to alter development or recovery.

We assessed the effect of scapular brown adipose tissue (BAT) denervation on dietary obesity in adult female Sprague-Dawley rats. In rats maintained for 32 days on an obesity-inducing regimen, BAT denervation produced significant reductions in food intake (83.4 vs. 94.4 kcal/day), weight gain (66.0 vs. 103.5 g), and carcass fat (19.3 vs. 27.6%). A subgroup of denervates consuming as many calories as controls (94.1 kcal/day) failed to gain more weight (92.2 g) or accumulate more fat (25.4%) than controls. In rats developing obesity for 32 days followed by 8 days on laboratory chow, weight change was unaffected by denervation during either weight gain (89.4 vs. 87.1 g for controls) or weight loss (21.2 vs. 22.1 g) phases, as was carcass fat (21.0 vs. 20.4%). BAT norepinephrine utilization was unchanged in nondenervated obese rats and those recovering from obesity. We did not, therefore, find evidence that under these experimental conditions sympathetic activation of BAT countered obesity during overconsumption or contributed to recovery from obesity.

Adipose Tissue↗
PubMed1985

Paraphimosis in seven debilitated horses.

This paper reports seven cases of penile paraphimosis which occurred in both entire and castrated horses in association with general debility. Two cases were discharged after treatment while still suffering from partial paralysis; one was discharged at the owner's request with complete paralysis; three were destroyed and one died during treatment. Identified causes of debility were malnutrition, severe parasitism, glucose malabsorption and salmonellosis.

Animals↗
PubMed1985

Precise estimation of carcass fat from total body water in rats and mice.

We investigated the utility of carcass water for predicting adiposity in a sample of 373 rats and mice from nine studies involving several models of obesity and experimental manipulations. A single regression equation was derived for estimating percentage carcass fat--%FAT predicted = -1.272 X %WATER + 95.96 (r = -.988). The function is linear across the range of %FAT observed (6.6% to 68.8%) and fits very well the data of each of the nine experiments. Comparisons between this function and the Lee Index as measures of obesity indicate, by contrast, the considerable imprecision of the latter method. Because studies in our analysis employed formalin fixation, we also provide an equation for use with unfixed tissue. This corrected function accounts for 97.8% of the variance in independent data from 19 published reports. We suggest that both of the functions presented here have general applicability for precise determination of body composition of rats and mice and, further, that the body water analysis offers significant advantages in terms of reduced time and expense.

Animals↗
PubMed1985

Infection with Chlamydia trachomatis immunotype J associated with trachoma in children in an area previously endemic for trachoma.

Chlamydia trachomatis immunotype J was isolated from the eye of a five-year-old Navajo child with trachoma. This is the first such isolate from a patient in an area previously endemic for trachoma. Chlamydial infection of the genitals among the Navajo Indians is common, and we have isolated immunotype J from the genital tract of women in this area. This most recent case points to the occurrence of "genital" trachoma. This occurrence adds evidence to the assertion that trachoma may be caused by the "genital" immunotypes of C. trachomatis. Therefore, the traditional distinction between ocular and genital strains may be artifactual.

Antibodies, Monoclonal↗
PubMed1984

Castration of horses and donkeys with first intention healing.

A simple technique for castration of adult horses which results in first intention healing was devised. The technique involves a 'closed' castration with or without a transfixed ligature on the spermatic sac and suturing the scrotal skin with polyglycolic acid suture material. The postoperative course was characterised by mild oedema only and by rapid recovery. The results obtained during the course of removing 311 scrotal testes from horses and donkeys of all ages are described and discussed. The technique is readily applicable in the field.

Animals↗