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Biomedical subjects

J R Webster

Publications and source records attributed to J R Webster.

At least 19 recordsLinked to original sources
PubMed1992

Effects of melatonin implants on insulin-like growth factor 1 in male red deer (Cervus elaphus).

Red deer stags have a seasonal pattern of growth, alternating between periods of summer weight gain and winter weight loss that are influenced by photoperiod and by exogenous melatonin. A seasonal pattern of plasma insulin-like growth factor 1, also influenced by photoperiod, underlies the seasonal growth pattern. The present studies aimed to determine the influence of exogenous melatonin, administered at various times of the year, on plasma IGF1 in adult red deer stags in New Zealand at 45 degrees S. In one study, 7-year-old stags (N = 9) were allocated to one of three treatment groups, either control or subcutaneous melatonin (3 x 18-mg coated implants (Regulin) per month) from November to February or from December to February. Blood was sampled, the stags were weighed, and antler status was recorded over 17 months. Melatonin treatment advanced the seasonal patterns of rise and fall of plasma IGF1 and of weight gain and loss. The cessation of melatonin treatment in February produced early antler casting and a second (out-of-season) antler and increased IGF1. In a second study, 4-year-old stags (N = 30) were allocated to one of six treatment groups as follows: three melatonin implants per months for 6 consecutive months beginning on 22 June, i.e., winter solstice, 4 August, 16 September, and 23 October; three melatonin implants per month for 12 months beginning on 22 June; and an untreated group. All animals were sampled as before for 12 months. Melatonin treatment beginning in July and August did not prevent the seasonal peak in IGF1, but the amplitude was lowered and antler casting delayed.

Animals↗
PubMed1992

Iatrogenic complications in high-risk, elderly patients.

BACKGROUND: This study explores the quality improvement potential of reviewing care for long-stay, elderly medicine service patients hospitalized for congestive heart failure, acute myocardial infarction, or pneumonia at a large Midwestern teaching hospital. METHODS: Medical records were reviewed for 120 patients aged 65 years or older who were discharged between January 1987 and June 1989, with hospital stays of 15 days or longer. Patients' severity of illness on admission was rated using the Medicare Mortality Predictor System; process quality of care was rated using a structured implicit review form for judging several dimensions of clinical assessment and decision making. Serious complications were coded by etiology and type and judged as possibly or probably preventable. Logistic regression was used to identify risk factors for iatrogenic events; multiple regression was used to assess potential outcome bias in ratings of overall quality of care. RESULTS: Of 120 medical records reviewed, 70 (58.3%) suffered at least one iatrogenic complication. Forty-three patients (35.8%) suffered an iatrogenic complication rated as potentially preventable. Significant predictors of all iatrogenic complications were quality ratings of initial physician assessment, patients' inability to walk unassisted, and low Glasgow Coma Score. For potentially preventable complications, quality ratings for physician documentation of functional status were also significant. Ratings for overall quality of care were not significantly influenced by the mere presence of death or complications. CONCLUSIONS: Iatrogenic complications are likely to be an extremely common experience for elderly medicine service patients with long lengths of stay. A significant portion of these complications may be potentially preventable with closer attention to initial assessment and documentation of patients' functional status.

Aged↗
PubMed1991

Role of the thyroid gland in seasonal reproduction. II. Thyroxine allows a season-specific suppression of gonadotropin secretion in sheep.

A series of four experiments was conducted to examine the previously described phenomenon that the thyroid gland is required for the breeding season to end in female sheep. Exp 1 tested the hypothesis that the thyroid is required because of its secretion of T4. Ewes thyroidectomized (THX) in the anestrous season either received T4 replacement or no further treatment; seasonal reproductive shifts were compared to those of thyroid-intact controls. All ewes were housed in conditions in which the end of the breeding season results from the expression of an endogenous annual rhythm. The ewes were ovariectomized and given constant-release estradiol (E) implants; reproductive state was assessed from serum LH levels to monitor seasonal shifts in response to E negative feedback. THX did not alter onset of the breeding season (LH rise) but, in the absence of T4 replacement, blocked its end (LH fall). T4 replacement reversed this effect of THX. Exp 2 tested the hypothesis that the thyroid is required only until the onset of the breeding season for reproductive activity to end at its normal time. THX after the breeding season began, however, sustained the elevation in LH, suggesting that the thyroid is required after reproductive onset for the breeding season to end. Exp 3 tested the hypothesis that THX causes a widespread disruption of steroid feedback responses. No effect of THX, however, was observed with respect to either the ability of an E rise to elicit the LH surge or the ability of E, or progesterone, to suppress LH secretion in the breeding season. Of the steroid feedback responses tested, THX altered only the seasonal shift in potency of E negative feedback. Exp 4 examined circulating T4 in thyroid-intact ewes over a 2-yr period. An annual cycle of serum T4 was detected; values reached a peak in winter (late breeding season) and a nadir in summer (late anestrus). Our findings support the concept that the thyroid gland plays a fundamental role in seasonal reproduction in the ewe. In this regard, secretion of T4 after the onset of reproductive activity is required for an endogenously generated change in the neuroendocrine axis that leads to an intensified E negative feedback and an end to the breeding season.

Anestrus↗
PubMed1991

Role of the thyroid gland in seasonal reproduction. III. Thyroidectomy blocks seasonal suppression of gonadotropin-releasing hormone secretion in sheep.

Previous studies demonstrated that the thyroid gland is required for the changes in LH secretion that lead to the end of the breeding season of female sheep, a reproductive transition generated within the ewe by an endogenous annual rhythm. The present study tested the hypothesis that this role of the thyroid is mediated via the GnRH neurosecretory system. The pulsatile secretion of GnRH into hypophyseal portal blood and LH into peripheral blood, as well as the neuroanatomical distribution of GnRH neurons and their light microscopic morphology, were compared among anestrous ewes and thyroidectomized (THX) ewes that failed to make the transition to the anestrous season. The study was conducted under photoperiodic conditions in which the transition to anestrus was generated by the endogenous rhythm. Each animal was ovariectomized and treated sc with a constant release implant of estradiol to normalize gonadal steroid status among thyroid-intact and THX ewes. High frequency pulses of GnRH and LH were evident in THX ewes that failed to make the transition to anestrus, whereas pulsatile secretion of GnRH and LH was generally not observed in thyroid-intact controls that had entered anestrus. This marked effect of thyroidectomy on GnRH secretion was not associated with widespread changes in the total number, distribution, or light microscopic morphology of GnRH neurons in the hypothalamus and preoptic area. Our finding that pulsatile secretion of GnRH is elevated in THX ewes that fail to make the transition to anestrus supports the hypothesis that the thyroid gland is required for the endogenously generated switch in function of the GnRH neurosecretory system that leads to the end of the breeding season of the ewe.

Animals↗
PubMed1991

Effects of melatonin implants on reproductive seasonality of male red deer (Cervus elaphus).

Red deer stags were treated with melatonin implants in 2 experiments designed to examine the control of reproductive seasonality. In Exp. 1, stags (n = 24) were allocated to 4 treatment groups: 2 groups were treated with 3 implants per stag each month from 8 November to 5 February (EM) or 9 December to 5 February (LM), 1 untreated group of control stags remained with the melatonin-treated stags (CC) and the other untreated control group remained isolated (IC). Melatonin treatment advanced the seasonal changes in scrotal circumference, liveweight, antler state and coat type compared with control stags. The extent of advancement was greater in EM than LM stags. In EM and LM stags, size of testes regressed rapidly and antlers were cast shortly after melatonin implants became exhausted in March. This was followed by an additional antler cycle and reproductive development and decline from June to November. EM and LM stags became synchronized with control stags 14-15 months after melatonin treatment began. The extra cycle of seasonal changes was more pronounced in EM than in LM stags. In Exp. 2, stags (n = 30) were allocated to 6 treatment groups: 4 groups were treated with 3 implants per stag at monthly intervals for 6 months from 22 June (J), 4 August (A), 16 September (S) and 23 October (O), a further group of stags was treated in the same manner for 12 months from 22 June (Y), and the remaining group was untreated (C). Compared with control stags, testicular regression and antler casting was delayed in Groups J, A and Y. These events occurred at the same time as in control stags in Groups S and O. Subsequent reproductive development was advanced in Groups S and O and delayed in Groups J, A and Y. The results demonstrated that treatment with melatonin implants in November or December advanced reproductive development. However, when stags were treated with melatonin implants from June to August, reproductive development was delayed, indicating a change in response to melatonin treatment during the year. The change in response to melatonin treatment between late winter and early spring was interpreted as a resetting of an endogenous circannual rhythm caused by a photoperiodic cue responsible for initiating the final stages of reproductive regression.

Animals↗
PubMed1991

Effect of melatonin implants on secretion of luteinizing hormone in intact and castrated rams.

Rams were treated with melatonin implants in 2 experiments designed to examine the control of reproductive seasonality. In Exp. 1, rams (n = 12) were allocated to 3 treatment groups: 2 groups were treated with 2 melatonin implants per ram for 4 months from 11 November (N) and 9 December (D) and the remaining group was untreated (C). The seasonal increase in luteinizing hormone (LH) pulse frequency and testes size was advanced in Groups N and D. A second seasonal cycle in LH secretion and testes size occurred in Groups N and D after melatonin implants became exhausted. In Exp. 2, rams (n = 20) were allocated to 4 treatment groups: 10 rams were castrated on 6 October and 1 group of entire rams (EM) and one group of castrated rams (CM) were treated with 2 melatonin implants per ram each month from 3 November until 8 January. The other group of entire rams (EC) and castrated rams (CC) was untreated. An increase in LH pulse frequency occurred after castration. Melatonin treatment increased LH pulse frequency in entire rams and reduced LH pulse frequency in castrated rams. The results demonstrated that the advanced reproductive development as a result of treatment with melatonin implants was due to an effect of melatonin on the hypothalamic pulse generator to increase LH pulse frequency. The ability of melatonin to influence LH pulse frequency in entire and castrated rams indicated that an effect of melatonin on the hypothalamic pulse generator is independent of testicular steroids.

Animals↗
PubMed1991

Unique aspects of respiratory disease in the aged.

Chronic obstructive pulmonary disease (COPD) is a common problem in the elderly, often resulting in reduced pulmonary capacity and serious functional disability. Contrary to commonly-held medical opinion, COPD often has a significant reversible component in the older patient and thus offers an excellent opportunity for successful treatment. Smoking cessation is the single most important measure to manage COPD. In addition, treatment with inhaled bronchodilators and corticosteroids, pulmonary rehabilitation programs, home oxygen therapy, and various preventive strategies are practical components for reversing COPD-induced dysfunction.

Adrenal Cortex Hormones↗
PubMed1989

Obtaining permission for an autopsy: its importance for patients and physicians.

This paper reviews the importance, benefits, and methods of increasing autopsy percentages. Its focus is on specific procedures for obtaining autopsy consent, particularly in terms of addressing the problems that most often interfere with obtaining permission for postmortem examination. Techniques for handling various misconceptions about autopsies are discussed. These guides for postmortem-related discussions with families will lead to improvement in overall physician performance and satisfaction.

Attitude to Death↗
PubMed1989

An autopsy-based study of diagnostic errors in geriatric and nongeriatric adult patients.

One hundred sixty-two consecutive adult autopsies (87 of subjects over age 65 years and 75 of subjects aged 23 to 64 years) performed at a university hospital were studied retrospectively by six internists to determine (1) if diagnostic errors were quantitatively or qualitatively different between the two age groups; (2) if the underlying causes of error (divided into nine categories) were different or age related in any way between the two groups; and (3) any aspects of care that related age to clinical outcome. We found the frequency of major clinical/autopsy discrepancies to be similar to those in previous studies (35%), but in only 7% of cases were these likely to have affected therapy/outcome. Ther was no difference in the frequency of major discrepancies between age groups. There were significantly more "unexpected" minor discrepancies in the older patients, probably related to the multiplicity and complexity of their problems, but these would have affected therapy/outcome in only 1 (3%) of 37 cases. The most common causes of 136 clinical "errors" in 151 autopsies were, in order of frequency: a diagnostic "blind spot," a conscious decision not to pursue a clinical finding (not a real "error"), failure to account for a symptom or sign, atypical presentations, and inadequate follow-up of abnormal laboratory findings. There were no differences between the geriatric and adult groups in terms of frequency or cause of the errors. We conclude that (1) there is no difference in the diagnostic accuracy regarding cause of death between geriatric and nongeriatric patients in the acute hospital environment, and (2) closer attention to basic knowledge and clinical skills and a special focus on judgment and reasoning skills, utilizing autopsy findings among other things, will lead to even further improvement in clinical care at all ages.

Adult↗
PubMed1987

Faculty on call.

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Faculty, Medical↗