Search PubMed⌕ Search

Biomedical subjects

R L Cooper

Publications and source records attributed to R L Cooper.

At least 145 records · Page 8Linked to original sources
PubMed1986

Trachoma: 1985 update in Western Australia.

Aboriginal preschool and school children were surveyed in the Eastern Goldfields Region and the Eastern Kimberley Region of Western Australia between 1979 and 1985. Statistics from these surveys show that there has been an apparent change in pattern of follicular trachoma since the National Trachoma and Eye Health Programme in some of the communities. The prevalence of follicular trachoma in the 0 to 9 year old age groups had declined from 26.4% in 1977 to 8.8% in 1984/1985 in the Eastern Goldfields and Red Centre combined (0.10 greater than p greater than 0.05). The prevalence reduction occurred in areas where there have been improvements in school hygiene and housing. The prevalence of cicatricial trachoma has also apparently declined from 65% in 1977 to 39% in 1985 in the Red Centre, from 39% in 1977 in the Eastern Goldfields to 21.7% in 1985, and from 58% in 1977 to 24.9% in 1985 in the Eastern Kimberley, Communities at risk were identified and recommendations made for frequency of continued screening, depending on age, distribution and location.

Adolescent↗
PubMed1986

Pituitary function following treatment with reproductive toxins.

Appropriate regulation of reproductive processes are dependent upon the integrity of pituitary function. In this selected review, we evaluate the evidence that certain environmental compounds exert their effect on reproductive function via a direct action on the pituitary gland. We also discuss examples of changes in pituitary hormone secretion that occur in response to changes in neuronal or gonadal control of the pituitary. A limited number of studies suggest that measures of pituitary hormone secretion provide an early and sensitive measure of a compound's potential effects on the reproductive system. However, the most striking aspect of this area is the sparse and inconsistent information describing pituitary function following exposure to environmental pollutants.

Animals↗
PubMed1985

Synergistic effects of estrogen and serotonin-receptor agonists on the development of pituitary tumors in aging rats.

The purpose of this study was to determine if pituitary 5-HT levels change as a function of age or endocrine state, and further if such changes are associated with pituitary pathology. Middle-aged constant estrous (CE) rats had larger (p less than 0.05) pituitary glands containing more (p less than 0.05) serotonin (5-HT) than those from young females or comparably aged, irregularly cycling rats. Ovariectomy lowered pituitary 5-HT content in middle aged CE rats. In contrast, pituitary weight and 5-HT content were increased in young rats of both sexes bearing subcutaneous, steroid-containing capsules that produced elevated levels of serum estradiol 17 beta. However, exogenous estrogen failed to raise pituitary 5-HT concentrations since pituitary weight increased more than 5-HT levels, even though the total amount of amine was significantly increased (p less than 0.05) compared with controls. These findings suggest that pituitary 5-HT increases during aging regardless of ovarian status and in addition, that total 5-HT content of the gland is increased further in hyperestrogenic states such as CE. Since pituitary adenomas occur more frequently in aged CE rats than in diestrous females or males, it was of interest to determine if 5-HT contributes to the tumorigenic effect of estrogen. Thus, the 5-HT receptor agonists zimelidine or quipazine were administered to ovariectomized rats bearing estrogen containing capsules. Rats treated with drugs had larger pituitaries containing more tumors than those receiving the steroid alone. However, these effects were dependent upon estrogen since pituitary pathology did not increase when ovariectomized rats were given 5-HT neuroleptics without the steroid.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1984

Assessing the risk of diabetic retinopathy.

We used multiple logistic regression to analyze cross-sectional data on 1,006 patients with diabetes mellitus who were examined in a rural diabetic screening program. The factors found to have independent and significant associations with the presence of retinopathy were duration of diabetes, albuminuria, serum creatinine, glycosylated hemoglobin, and plasma glucose levels, blood pressure, and percentage of desirable weight. By comparing the contribution of each significant factor to the deviance from the regression models, we estimated the relative importance of each. Duration of diabetes was by far the most important predictive factor. The logistic model provided a good fit to the observed prevalence rates in various risk groups but was less satisfactory for predicting the presence or absence of retinopathy in individual patients. The discovery of presently unknown risk factors may improve this situation.

Adolescent↗
PubMed1984

Effect of luteinizing hormone-releasing hormone antiserum on sexual behavior in the female rat.

Various components of sexual receptivity were measured in ovariectomized, estrone-primed female rats following direct placement of luteinizing hormone releasing hormone (LH-RH) or a LH-RH antiserum into the medial preoptic area. Two hours after treatment with LH-RH antiserum, rats showed a significant increase in lordosis behavior indicative of increased sexual receptivity. When tested 3 and 7 hours after treatment, both LH-RH antiserum and LH-RH-treated rats displayed increased lordosis behavior. Similar treatment with a specific peripheral LH-RH agonist and antagonist had no effect on sexual behavior. Proceptive behavior was absent or minimal in all groups and therefore was not affected by the different treatments. Similarly, there was no difference in the rejection quotients of the females representing the various treatment groups. These results demonstrate that the same behavioral response can be observed in animals treated centrally with LH-RH and a highly specific LH-RH antiserum. Similar treatments with a specific peripheral LH-RH agonist or antagonist were without effect. These results suggest that the characteristics of LH-RH recognition sites in the brain are different from those in the pituitary.

Animals↗
PubMed1984

Catecholamines in aqueous humour of glaucoma patients.

Aqueous humour catecholamine concentrations were assayed in open angle glaucoma, and cataract patients during surgery, under general anaesthesia. Plasma catecholamines were measured at the same time. Aqueous humour noradrenaline is apparently reduced by pretreatment with adrenaline, timolol and pilocarpine. (Noradrenaline concentrations were 0.599 +/- 0.239 ng/ml in glaucoma, and 0.970 +/- 0.445 ng/ml in cataract patients.) Dopamine was found in two of six cataract patients (0.123 and 0.318 ng/ml), and in all the glaucoma group (0.221 +/- 0.170 ng/ml). Plasma noradrenaline concentration was probably increased in glaucoma, when compared to the cataract patients. These results confirm our findings in the non-human primate, and suggest that adrenaline may act, at least in part, by causing denervation or inhibition of noradrenaline release in the anterior segment of the eye, and probably by release of dopamine into the aqueous humour. The unexplained and new finding of dopamine in the aqueous humour may have some bearing on the action of dopaminergic drugs for the treatment of glaucoma. Future treatment of ocular hypertension may rely more on sympathetic denervation than on conventional adrenergic therapy.

Adrenergic Agonists↗
PubMed1984

Endocrine status versus chronologic age as predictors of altered luteinizing hormone secretion in the "aging" rat.

LH release in response to GnRH injected at 1400 h was measured in young (3-4 months), middle-aged (10-11 months), and old (19-20 months) female rats. Data were compared when animals were grouped by chronological age or according to their vaginal smear pattern 3-4 weeks before treatment, i.e. regular 4-day cycles, constant vaginal cornification (CVC), or persistently leukocytic smears (PL). Compared to young, regularly cycling females (injected on vaginal estrus or diestrus II), the amount of LH released by all age groups with CVC or PL smears was significantly diminished. However, regardless of age, the amount of LH released by CVC females was similar for each dose of GnRH. Similarly, there was no difference in the amount of LH released by the young, middle-aged, and old PL females at each dose of GnRH. Finally, the amount of LH released by the CVC females was uniformly higher than the amount of LH released by age-matched PL females. In contrast, comparison of LH release after GnRH injection in young and middle-aged rats with regular 4-day vaginal cycles showed that the middle-aged rats released significantly less LH on proestrus. These data suggest that changes in the ability of the pituitary to release LH in the older noncycling female rat occurs as a consequence of the altered endocrine status in the animal and not as a result of the chronological age per se. Changes in the ability of the pituitary of the middle-aged, regularly cycling female rat to release LH in response to GnRH may contribute to the age-related disruption of regular ovarian cycling.

Aging↗
PubMed1984

Aqueous humor catecholamines.

The catecholamines norepinephrine, (NE) epinephrine (E) and dopamine (DA) were detected for the first time in the aqueous humor of humans under general anesthesia and monkeys under ketamine. The catecholamine levels in aqueous humor of 9 humans were assayed. NE was 0.796 +/- 0.457 ng./ml., E ranged between 0 and 0.132 ng./ml. in 4 out of 9 subjects, and DA was found in 2 of the 9 eyes. (0. 123ng ./ml. and 0. 318ng ./ml..) Plasma levels were measured in 8 of the human subjects at the time of aqueous sampling -NE was 0.311 +/- 0.171, E ranged between 0 and 0.097 (4 out of 8 subjects) and DA was detected in one subject- 0.037 ng./ml.. Monkey aqueous levels were NE:2.843 +/- 0.668 and DA:0.462 +/- 0.177 ng./ml., with an intact iris. (N = 8 eyes.) NE was 0.497 +/- 0.049, and DA 0.426 +/- 0.218 ng./ml. after total iridectomy. (N = 4 eyes) E was not detected in the monkey under these conditions. Whilst NE may be produced in part by the iris, DA levels were not affected by iridectomy. This implies that DA may be produced by structures unrelated to sympathetic nerve endings of the iris in the anterior segment of the non-human primate eye, perhaps by diffusion from the ciliary body or retina. Ketamine is known to inhibit catecholamine uptake, which may explain the high levels measured in the monkey. Human aqueous catecholamine levels measured under anesthesia may be affected by a variety of the drugs used. It is postulated that dopaminergic neurones and associated receptors may be present in the anterior segment of the eye. This may explain the presence of aqueous humor dopamine and the effects of dopaminergic drugs on intraocular pressure.

Adult↗
PubMed1983

Extensive bleeding following extractions in a patient undergoing chronic hemodialysis.

A prolonged epistaxis following routine dental extractions was observed in a 50-year-old woman with a history of chronic hemodialysis. Despite the clinical impression of a significant coagulopathy, extensive hematologic testing failed to reveal any abnormalities. Recent evidence suggests that a prostaglandin (prostacyclin) with platelet antiaggregatory properties may be responsible for episodes of prolonged bleeding reported in patients undergoing hemodialysis.

Epistaxis↗
PubMed1983

Draining pus from the cornea.

Thirteen patients with varying grades of suppurative keratitis were studied with regard to their response to keratoplasty. In all patients there was a rapid improvement in symptoms and signs. In eight of the 13 there was restoration at least of previous function: one patient lost all vision due to secondary closed-angle glaucoma, because he refused further surgery. Corneal graft opacification occurred in three eyes; one other became partially opaque; whilst in a fourth, the lamellar graft remained clear while the original autograft failed. At last follow-up, all eyes were normotensive and free of symptoms. Keratoplasty should assume an important part of the management of suppurative keratitis, from both theoretical and practical considerations.

Adult↗
PubMed1983

Progress in continual eye pressure monitoring.

Observations of intraocular pressure (IOP) variations in response to CO2, adrenaline, speech and compression of the neck veins were documented by continual monitoring of IOP by radiotelemetry. Carbon dioxide increased IOP in the supine, but not in the erect, conscious subject. Adrenaline 2% caused a rapid short-lived painful increase in IOP, followed by a profound decrease. This was due to an increase in facility of outflow and was associated with paralysis of the sympathetic supply to the iris. Speech caused a small rise in IOP which was reversed by rest in silence. Compression of the neck veins caused a variable increase in IOP. These physiological variations in IOP may contribute to the errors of tonometry.

Carbon Dioxide↗
PubMed1982

Altered pituitary responsiveness to gonadotropin- releasing hormone in middle-aged rats with 4-day estrous cycles.

We employed a perifusion system to compare the GnRH responsiveness of pituitaries removed from young (3-6 months old) and middle-age (10-14 months old) female rats with 4-day estrous cycles in order to determine whether changes at this locus may contribute to alterations in LH secretion which precede a loss of regular estrous cycles. Pituitaries were removed and halved on each day of the 4-day cycle; one hemipituitary was retained for measurement (by RIA) of LH content. The second half was perifused for 2.5 h with medium 199 plus BSA, then stimulated for 6 h with 10(-7) M GnRH in medium 199 plus BSA. Results were as follows. 1) Within young and middle-aged groups, the magnitude of GnRH-stimulated LH release varied with stage of the estrous cycle (proestrus, diestrous day 2 greater than estrus, diestrous day 1). General patterns of LH release were similar between age groups; however, pituitaries removed from middle-aged females released significantly less LH on proestrus and diestrous day 1 than did those removed from young females. 2) The time required to reach maximal response to GnRH also varied with the estrous stage; response times were shortest on proestrus and estrus in both age groups. The time to maximal response was significantly longer in the middle-aged vs. the young group on all days of the estrous cycle except diestrous day 2. 3) Within age groups, pituitary LH content varied with the estrous cycle in a pattern similar to that of GnRH responsiveness. Between groups, LH content in middle-age females was equivalent to or greater than that in young females on all days of the cycle. These results indicate that reduced pituitary responsiveness to GnRH may contribute to the delayed attenuated proestrous LH surge that precedes reproductive senescence in the female rat.

Aging↗
PubMed1981

Prevention of corneal burns during high-energy laser iridotomy.

We used a plano hydrophilic bandage contact lens to protect the corneal epithelium and stroma from burns during laser iridotomy. The reduction of energy losses with this method, by the avoidance of corneal epithelial opacities, increases the chance of successful iridotomy when many applications of the laser are needed.

Burns↗
PubMed1981

Image splitting--a technique for measuring retinal vascular reactivity.

The observation of changes of pial vessel calibre has withstood the test of time in assessing cerebrovascular reactivity. A recent refinement has been the adoption of the image splitting television technique of Baez, which allows accurate and rapid measurements of vessel calibre to be made in situ. This method has been successfully applied to the eye, where the retinal vessels are readily visible through the pupil. Results are presented of preliminary experiments in normal persons, in whom an induced increased in intraocular pressure was associated with retinal vasodilatation.

Arterioles↗