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Biomedical subjects

R Gray

Publications and source records attributed to R Gray.

At least 307 records · Page 17Linked to original sources
PubMed1985

Percutaneous abscess drainage.

We have drained 50 abscesses in 40 patients. The success rate was 100% for entering the abscess cavities and 98% for establishing catheter drainage. The success rate for treating the abscess (i.e., no surgery required) was 88%. We drained all abscesses for which a safe access route was available, regardless of the abscess's characteristics. Abscesses which are not unilocular may be successfully treated by percutaneous drainage. In critically ill patients and those unsuitable for surgery, catheter drainage is useful until the patient becomes stable. When surgery is not feasible, percutaneous procedures may be the patient's only hope for survival.

Adult↗
PubMed1985

Rectification of single GABA-gated chloride channels in adult hippocampal neurons.

The properties of single chloride channels activated by gamma-aminobutyric acid (GABA) were investigated with hippocampal slices from adult guinea pigs. After the slices were treated with proteolytic enzymes, gigaseal recordings were made from excised patches of pyramidal or granule cell membranes. This newly developed preparation permits the application of patch-clamp techniques to the adult mammalian central nervous system. Guinea pig hippocampal slices were prepared in a conventional manner. Once prepared, the slices were treated with two different enzymes for brief periods and gently agitated. Slices generally split apart along the boundaries of the cell body regions, exposing neuronal somata. Standard patch-clamp techniques were used for the gigaseal recordings from excised patches. Solutions for both sides of the patches consisted of symmetrical concentrations of chloride, with all cation channels blocked. GABA at concentrations of 0.5-1.0 microM was added to the solution for the extracellular side of the patches. At transmembrane potentials negative to the chloride reversal potential (0 mV), the conductance through the GABA-gated chloride channels was approximately 20 pS. When the transmembrane potential was changed to positive values, the chloride conductance increased dramatically. For example, at +40 mV the conductance through the GABA-gated channels was almost 40 pS. Ramp-clamp commands were used to measure the current-voltage (I-V) relationship through single open channels. The open-channel I-V curves displayed outward rectification. The relationship between open-channel conductance and voltage could be fitted reasonably well by a single energy-barrier model for the channel, with the higher energy barrier placed near the cytoplasmic side of the membrane (at a fractional distance through the membrane of 0.73).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Adjuvant tamoxifen treatment of elderly women with stage II breast cancer. A double-blind comparison with placebo.

One hundred seventy elderly women with stage II breast cancer, stratified on the basis of the number of positive axillary nodes and estrogen receptor status, were randomly assigned to receive tamoxifen or placebo for 24 months in a prospective, double-blind, adjuvant trial. The median age was 71 years with a range from 65 to 84 years. The overall percentage of patients disease-free at 4 years was 76% for those given tamoxifen and 52% for those given placebo (p = 0.0004). Benefit was seen in all subgroups of patients treated with tamoxifen. Two years of tamoxifen therapy represents an effective postoperative adjuvant treatment for elderly women with stage II breast cancer, resulting in improved time to relapse, statistically fewer distant first recurrences, and minimal toxicity. No improvement in overall survival has been seen yet.

Aged↗
PubMed1985

Hyperparathyroid bone disease in chronic renal failure.

Much has been learnt over the past 80 years of the pathogenesis and management of hyperparathyroid bone disease in uraemia. Clinically it has changed from a rare disorder of childhood and adolescence to a common and difficult problem in patients maintained on dialysis programmes. Whereas effective treatments are now available for hyperparathyroid bone disease, these are not curative and there is clearly much more work to be done before a full understanding of its pathogenesis, and the best methods of treatment and prevention, can be reached.

Bone Diseases↗
PubMed1984

Effects of hormonal contraceptives on milk volume and infant growth. WHO Special Programme of Research, Development and Research Training in Human Reproduction Task force on oral contraceptives.

WHO conducted a three-centre study in Hungary and Thailand to evaluate the effects of hormonal contraception on lactation and infant growth. Women choosing oral contraceptives were randomly assigned to a combined oral contraceptive containing 30 micrograms ethinyl estradiol and 150 micrograms levonorgestrel (N = 86) or a progestin-only preparation containing 75 micrograms dl-norgestrel (N = 85). Identical packaging and treatment schedules allowed double-blind observation. One-hundred-and-eleven women using no contraception or non-hormonal methods acted as controls. In the two Thai centres 59 women using depot-medroxyprogesterone acetate formed an additional comparison group. All subjects were healthy women with normal deliveries, whose infants had normal birth weights and satisfactory growth in the neonatal period. Breast milk volume was determined by pump expression using standardized procedures. Information was obtained on nursing frequency and supplementation, infant growth and morbidity. Pretreatment observations at 6 weeks post-partum were used as a baseline, and subjects were followed-up at 9, 12, 16, 20 and 24 weeks post-partum. Women using combined oral contraceptives had a decline in milk volume within 6 weeks of initiating treatment, whereas no significant decrease was observed in the other treatment groups. After 18 weeks of treatment, combined oral contraceptive users experienced a 41.9% decline in milk volume, compared to 12.0% with progestin-only minipills and 6.1% in the non-hormonal controls. The prevalence of complementary feeding and withdrawals due to inadequate milk supply were comparable in the four treatment groups. However, data were not available on the daily amounts of complementary feeds. There were no significant differences in growth of infants between treatment groups. Thus, women may have compensated for declines in milk volume by more supplementary feeding or by more prolonged and intense suckling episodes. We conclude that 30 micrograms estrogen-containing combined oral contraceptives impair milk secretion, but in the selected healthy group of mothers and children studied with the prevailing level of supplementary feeding, this did not adversely affect infant growth.

Adult↗
PubMed1984

Improved control of bulky prostate carcinoma with sequential estrogen and radiation therapy.

Patients with bulky prostate cancer have usually been treated by palliative measures because the likelihood of tumor control with definitive irradiation has been low and the development of distant metastases high. The addition of estrogen to irradiation has not been shown to be of value. However, we believe the method of estrogen administration may have been the cause for the apparent lack of benefit. Estrogen had been started either concurrent with irradiation or had been used for palliation and was given for long and unscheduled time periods prior to irradiation. We have used estrogen for two months prior to and concurrent with irradiation. We postulated that in those patients with estrogen responsive cancer, the reduced tumor burden prior to irradiation could enhance tumor control and survival. Between 1975 and 1980, 25 patients with bulky prostate cancer received sequential estrogen and irradiation, 12 patients irradiation alone and six patients irradiation after having become refractory to long-term estrogen use. One patient was lost to follow-up. Eighteen of 25 (72%) treated by sequential estrogen and irradiation, 14/17 (82%) with estrogen responsive cancer and 4/8 (50%) with estrogen resistant cancer had a complete tumor response. Six of 11 (55%) patients treated by irradiation alone and 2/6 (33%) treated by irradiation for estrogen refractory cancer had a complete tumor response. Disease-free survival was observed in 13/25 (52%) treated by sequential estrogen and irradiation, and 8/17 patients (47%) with irradiation. It is also possible the improved survival in the estrogen responsive group was a direct result of improved local control. Persistent local disease can act as a source for distant metastases. Distant metastases was observed in 15% of patients when the primary tumor was controlled and 30% when there was persistent or recurrent local disease. Also, progressive local disease can be an important cause of death. This was most evident in our patients with estrogen refractory cancer. Almost all patients in this group had progressive local disease that caused serious urinary bleeding and urinary infection that were considered the major cause of death. Our results suggest bulky prostate cancer should be aggressively treated when first diagnosed. The value of adjunct estrogen is unproven. Our results with the use of estrogen prior to and concurrent with irradiation is encouraging. Estrogen may shrink the cancer and allow for a more favorable geometry for external irradiation. Tumor control and survival may be thereby improved.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1984

Nasal septal chondrosarcoma (a long-term follow-up report).

A case of nasal septal chondrosarcoma is presented which, after radical surgery, recurred after seven and a half years. The post-mortem findings showed gross local spread and dural seedlings. The clinical implications are discussed and the literature reviewed.

Chondrosarcoma↗
PubMed1984

Construction of receiver operating characteristic curves when disease verification is subject to selection bias.

The estimates of ROC curves, which are frequently used in the assessment of diagnostic tests, may be biased if the sample is restricted to subjects whose disease status has been definitively verified. A method to provide an unbiased estimate of the ROC curve under these sample conditions is proposed. The new method requires information on the probability distribution of test results in the population from which the verified sample is drawn. It is illustrated using data from a study of computed tomography for fever of uncertain origin.

Diagnosis↗
PubMed1984

Severe neutropenia associated with sustained-release procainamide.

Neutropenia is a rare complication of procainamide therapy. However, over a period of 20 months, 8 patients developed severe neutropenia while taking a sustained-release preparation of the drug. Seven patients presented with fever and constitutional symptoms and one patient was asymptomatic. Bone marrow examinations showed myeloid aplasia or maturation arrest in 5 patients and myeloid hyperplasia in 1. Neutropenia resolved within 30 days of drug withdrawal, and all patients survived. A case-control study showed a significant association between sustained-release procainamide therapy and severe neutropenia in 5 of 114 patients (4.4%) recovering from open-heart surgery (Mantel-Haenszel chi square = 13.84; p less than 0.001). Thus, life-threatening neutropenia may be common with sustained-release procainamide preparations.

Aged↗
PubMed1984

The uses of corpus cavernosography. A review.

In a series of 18 corpus cavernosograms (CC) we encountered 12 patients with Peyronie's disease, four normals, one with hypoplastic corpora and one with penile fracture. All examinations were successful and there was one complication, a case of post-procedural priapism. CC is a valuable procedure in the evaluation of impotence.

Adult↗
PubMed1984

Nitrosamine carcinogenesis in 5120 rodents: chronic administration of sixteen different concentrations of NDEA, NDMA, NPYR and NPIP in the water of 4440 inbred rats, with parallel studies on NDEA alone of the effect of age of starting (3, 6 or 20 weeks) and of species (rats, mice or hamsters).

A Weibull analysis is presented of the dose and time relationships for the effects on 4 080 inbred rats of chronic ingestion in the drinking water of 16 different doses of N-nitroso-dimethylamine (NDMA) and of N-nitrosodiethylamine (NDEA). The sites chiefly affected were the liver (by both agents) and the oesophagus (by NDEA only). Since the experiment continued into extreme old age, effects became clearly measurable even at a dose of only 0.01 mg/kg per day, which is an order of magnitude lower than previously achieved. (After only two years of treatment, however, the 'TD50' doses needed to halve the proportion of tumourless survivors would have been about 0.06 mg/kg per day of NDEA and about 0.12 mg/kg per day of NDMA.) The general pattern of response was that the log probability of remaining tumourless was given by the product of two terms, the first (the 'Weibull b-value') depending on the dose-rate but not on the duration of exposure, and the second depending not on dose at all but on (approximately the seventh power of) duration. For oesophageal tumours, the 'Weibull b-value' was approximately proportional to the cube of the dose-rate of NDEA (males 21 d3, females 11 d3, where d = dose-rate in mg/kg adult body weight/day, and the background incidence was unmeasurably low. For liver tumours induced by NDEA, the b-value was approximately proportional to the fourth power of dose-rate + 0.04 mg/kg per day (males, 19 (d + 0.04)4; females, 32 (d + 0.04)4), although the relationships were slightly different for the different subsites of liver tumour. This one formula implies both approximate linearity at low doses and an approximately cubic relationship within the higher range of doses that was studied. For liver tumours induced by NDMA, the Weibull b-value was approximately proportional to the sixth power of dose rate + 0.1 mg/kg per day (males, 37 (d + 0.1)6; females, 51 (d + 0.1)6), again with variation between liver subsites, and again implying approximate linearity at low doses. The difference between the latter two relationships may represent differences in the induction of particular DNA repair enzymes by NDMA and NDEA, or in the effects of those enzymes on methylated and on ethylated DNA. These formulae should, of course, be trusted only in the range of doses from which they were derived, and particularly not for those above it.(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors↗