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Biomedical subjects

D C Morgan

Publications and source records attributed to D C Morgan.

At least 19 recordsLinked to original sources
PubMed2003

Observation of weak-limit quasiparticle scattering via broadband microwave spectroscopy of a d-wave superconductor.

There has long been a discrepancy between microwave conductivity measurements in high temperature superconductors and the conductivity spectrum expected in the simplest models for impurity scattering in a d-wave superconductor. Here we present a new type of broadband measurement of microwave surface resistance that finally shows some of the spectral features expected for a d(x2-y2) pairing state. Cusp-shaped conductivity spectra, consistent with weak impurity scattering of nodal quasiparticles, were obtained in the 0.6-21 GHz frequency range in highly ordered crystals of YBa2Cu3O6.50 and YBa2Cu3O6.99.

Journal Article↗
PubMed1999

New method for detection of heart allograft rejection: validation of sensitivity and reliability in a rat heterotopic allograft model.

BACKGROUND: Patients with inflammatory heart muscle diseases would benefit from a safe, convenient, rapidly performed diagnostic technique with real-time results not involving tissue removal. We have performed a detailed evaluation of detection of heart allograft rejection by autofluorescence in a heterotopic abdominal rat heart allograft model ex vivo. METHODS AND RESULTS: Recipient rats with allograft (Lewis to Fisher 344; n=71) and isograft (Lewis to Lewis; n=33) hearts, treated with cyclosporine or untreated, were killed at days 2, 4, 7, 14, 21, 28, and 56 after transplant. Nontransplant controls with (n=24) or without (n=24) immunosuppressive therapy were also studied. When the rats were killed, autofluorescence spectra were acquired under blue-light excitation from midtransverse ventricular sections of native and transplanted hearts. Corresponding sections were then evaluated pathologically by a modified International Society for Heart and Lung Transplantation (ISHLT) grading schema. The spectral differences between rejecting and nonrejecting hearts were quantified by linear discriminant functions, producing scores that decreased progressively with increasing severity of tissue rejection. Mean+/-SD discriminant function scores were 2.9+/-1.6, 1.8+/-2.2, -0.1+/-2.8, -1.2+/-2.3, and -2.3+/-3.0 for isografts and allograft ISHLT grades 0, I, II, and III, respectively (Spearman rank-order correlation -0.6; P<0.001, test for trend). Cyclosporine had no detectable effect on the spectra. CONCLUSIONS: The correlation between changes in autofluorescence spectra and ISHLT rejection grade strongly supports the possibility of catheter-based, fluorescence-guided surveillance of rejection.

Animals↗
PubMed1998

Four years' experience of a senior house officer rotation in general medicine including general practice.

A four-month post in general practice was included as an option available to doctors applying for a year-long medical senior house officer (SHO) rotation since August 1993. This study sought the views of SHOs before and after undertaking the general practice post. SHOs gained an understanding of modern general practice and changed their views about certain aspects of general practice. They reported gaining a range of generic skills, which included communication, consultation, and clinical skills. These perceived benefits suggest that such experience merits wider adoption and further evaluation.

Adult↗
PubMed1997

Gonococcal infection in cerebrospinal fluid and the presence of a ventriculoperitoneal shunt.

BACKGROUND: Neisseria gonorrhoeae is one of the most common organisms associated with pelvic disease in a woman of reproductive age. CASE: We present an unusual case of cerebrospinal fluid infection with N. gonorrhoeae in a woman with a ventriculoperitoneal shunt who complained of abdominal pain. Her shunt was removed and after adequate antibiotic therapy, it was re-inserted. CONCLUSION: Sexually active women, especially those with ventriculoperitoneal shunts, should be encouraged to use a barrier method of contraception, and should have a pelvic examination as part of their evaluation when they present with complaints of abdominal pain.

Adult↗
PubMed1997

Resistance to bone resorbing effects of PTH in black women.

Black women have a lower incidence of vertebral and hip fractures than white women, possibly due to differences in skeletal and mineral metabolism. One suggested mechanism is that blacks have decreased skeletal sensitivity to parathyroid hormone (PTH). To test this hypothesis, we infused h(1-34)PTH in healthy premenopausal black (n = 15) and white (n = 18) women over 24 h and measured serum and urine indices of bone turnover and calcium metabolism throughout the infusion. At baseline, the mean 25-hydroxyvitamin D (25(OH)D) concentration was significantly lower in black women (46%). There were also nearly significant trends toward higher PTH and lower urinary calcium and pyridinoline levels in black women. During infusion, there were no racial differences in the mean (1-34)PTH levels achieved or in resultant elevations of serum calcium or 1,25-dihydroxyvitamin D (1,25(OH)2D) levels. Endogenous parathyroid suppression (measured by (1-84)PTH levels) was also similar between blacks and whites. There was an initial decline in urinary calcium/creatinine in both groups with a greater reduction in black women early in the infusion period (p < 0.05 at 8 h). Furthermore, blacks had lower levels of urinary calcium/creatinine throughout the infusion (p < 0.05 group difference). Bone formation markers (carboxy-terminal propeptide of type I procollagen and osteocalcin) decreased within 8 h and continued to decline throughout the infusion with no distinguishable racial differences (p < 0.05 time trend for both). The most dramatic difference between black and white women in response to PTH infusion was represented by the bone resorption markers. Three separate metabolites of bone resorption (cross-linked N-telopeptide of type I collagen, cross-linked C-telopeptide of type I collagen, and free pyridinoline) all showed substantially greater elevations in white (mean peak increments 399, 725, and 43%) compared with black women (mean peak increments 317, 369, and 17%) during the infusion (p < 0.05 group differences for all three variables). These data strongly suggest that blacks have decreased skeletal sensitivity to the acute resorptive effects of increased PTH. This finding indicates that calcium homeostasis may be accomplished in blacks (during times of relative calcium deficiency) by greater conservation of calcium from nonskeletal sources (most likely renal) with relative preservation of skeletal tissue. These differences in calcium economy could account, at least in part, for the increased bone mass and lower incidence of osteoporotic fractures in black women.

Adult↗
PubMed1988

pH of organ-culture-stored corneas.

Changes in intracorneal and storage-medium pH values of organ-culture-stored cat corneas were monitored over a 4-week period. The intracorneal pH was determined using the phosphorus-31 magnetic resonance spectroscopy (31P MRS) chemical shift of inorganic orthophosphate in conjunction with a standard pH titration curve. We incubated 32 adult cat corneas using two similar standard organ-culture methods, one with chondroitin sulfate (method 1) and the other without (method 2). Time-course data at 0, 1, 3 and 4 weeks of storage were used to calculate the rate of pH change. The intracorneal pH was not changed significantly for either organ-culture method; however, the storage-medium pH rate of change declined significantly for both methods (method 1, 0.15 pH units/week; method 2, 0.12 pH units/week). The difference between intracorneal and storage-medium pH values over time increased at a rate of 0.12 and 0.11 pH units/week for method 1 and method 2, respectively. The declining storage-medium pH in conjunction with the maintenance of intracorneal pH contributes to an increased metabolic demand on the cornea.

Animals↗
PubMed1979

Problems with handling the BE10 series hearing aids among elderly people.

Seven items of activity related to patients' ability to handle behind-the-ear hearing aids (BE11/12) were investigated to establish the effects of age, sex and functional disability. One hundred and thirty-six patients were examined; all were first-time users of hearing aids. Over two-fifths of the sample had problems with manipulating the volume control and over a third had difficulty with inserting the earmould and changing the battery. For both men and women, the difficulties with the volume control and earmould were significantly associated with functional disability. Difficulties with these tasks were also significantly related to age and sex. Patients aged 75 years of age or more had greater difficulties than those who were younger and women had more difficulty than men.

Age Factors↗
PubMed1977

Self-assessment of hearing impairment: test of the expanded hearing ability scale questionnaire on hearing impaired adults in England.

The National Center for Health Statistics developed a questionnaire for self-assessment of hearing impairment which has been widely tested in the United States. The performance of this questionnaire was tested on a sample of 131 people in England, known to have hearing impairment and gave results very similar to those obtained in the United States. These results are compared with a randomly selected sample from the general population. Characteristics of the hearing ability scale derived from the questionnaire are discussed and some suggestions made for a modified version of the questionnaire. The relationship between the average pure tone threshold and the score derived from the hearing ability scale questionnaire is described and takes the form of a bounded relationship with scale score indicating the minimum threshold level.

Adolescent↗
PubMed1976

Myocardial infarction: a comparison between home and hospital care for patients.

To compare the results of home and hospital treatment in men aged under 70 years who had suffered acute myocardial infarction within 48 hours 1895 patients were considered for study in four centres in south-west England. Four-hundred-and-fifty patients were randomly allocated to receive care either at home by their family doctor or in hospital, initially in an intensive care unit. The randomised treatment groups were similar in age, history of cardiovascular disease, and incidence of hypotension when first examined. They were followed up for up to a year after onset. The mortality rate at 28 days was 12% for the random home group and 14% for the random hospital group; the corresponding figures at 330 days were 20% and 27%. On average, older patients and those without initial hypotension fared rather better under home care. The patients who underwent randomisation were similar to those whose place of care was not randomised, except that the non-randomised group contained a higher proportion of initially hypotensive patients, whose prognosis was poor wherever treated. These results confirm and extend our preliminary findings. Home care is a proper form of treatment for many patients with acute myocardial infarction, particularly those over 60 years and those with an uncomplicated attack seen by general practitioners.

Adult↗
PubMed1976

Ethanol elimination rates in normal and ethanol dependent animals.

Ethanol elimination rates were determined in rats using an intravenous route of ethanol administration after several experimental manipulations. Twenty-four hr food deprivation resulted in a 30% reduction to 35 mg/100ml blood/hr in elimination rate from a non-deprived rate of 50 mg/100 ml blood/hr. After 2 months of ethanol drinking (5% v/v), 24 hr starvation resulted in only a 10% reduction in elimination rate (45 mg/100 ml blood/hr), and did not increase the non-food-deprived rate (49.2 mg/100 ml blood/hr) over that obtained in the above animals' drinking water rather than 5% ethanol. Animals which chronically overdrank ethanol or water for 3 months on a schedule-induced polydipsia procedure, known to result in ethanol physical dependence, showed a decreased rate of ethanol elimination (37.9 mg/100 ml blood/hr for water drinkers) in the non-food-deprived condition. By providing 750 mg of liver powder daily as a food supplement in the ethanol overdrinking regimen, the ethanol elimination rate remained at a rate comparable to the normal animal (48.4 mg/100 ml blood/hr).

Alcohol Drinking↗
PubMed1975

Chest symptoms in farming communities with special reference to farmer's lung.

Surveys were carried out on random samples of the farming population in Devon and Wales in order to estimate the prevalence of respiratory symptoms and of positive precipitin reactions to thermophilic fungi. Bronchitis, as defined, was common among the Welsh hill farmers, and the proportion of positive serological tests was higher in both the areas surveyed in Wales as compared with Devon. All three surveys confirmed a previous finding that the proportion of positive precipitin tests was higher among non-smokers than smokers. Although the numbers were small there was some indication that measurement of peak expiratory flow showed different relationships with age in non-smokers according to the presence or absence of positive precipitin tests. The difficulty of determining prevalence rates for farmer's lung is discussed, but the results suggest a rate not dissimilar to those found in two areas of Scotland which were more than 20 times higher than any figure previously reported in Britain.

Adolescent↗
PubMed1975

Moving to a health centre--the effect on workload and patients.

A detailed study of the workload of an urban practice was made during a six-month period before and after moving into a health centre to see if the pattern changed after the move. It was found that the services provided enabled a much greater proportion of routine work to be done by the practice nurse so that the doctor could spend more time with the patients seen by him.A survey of the opinion of patients showed that the great majority was pleased with the services offered in the new premises and did not feel that they had lost contact with their own doctor.

Community Health Centers↗