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Biomedical subjects

D S Gray

Publications and source records attributed to D S Gray.

At least 19 recordsLinked to original sources
PubMed2006

Fibrous myopathy as a complication of repeated intramuscular injections for chronic headache.

Two cases of fibrous myopathy associated with repeated, long-term intramuscular injections for treatment of chronic temporomandibular joint pain and chronic headache, respectively, are described. Both patients developed severe, function-limiting contractures in upper and lower extremity muscles used as injection sites. In one of the cases, the contractures were painful. Electrophysiological testing, magnetic resonance imaging and muscle biopsy results were all consistent with myopathy and replacement of skeletal muscle with noncontractile fibrous tissue. These cases are presented to increase awareness of fibrous myopathy and to promote surveillance for this serious potential complication of long-term intramuscular injections in chronic headache and other pain patients.

Adult↗
PubMed2002

Mitigation of tokamak disruptions using high-pressure gas injection.

High-pressure gas-jet injection of neon and argon is shown to be a simple and robust method to mitigate the deleterious effects of disruptions on the DIII-D tokamak. The gas jet penetrates to the central plasma at its sonic velocity. The deposited species dissipates >95% of the plasma by radiation and substantially reduces mechanical stresses on the vessel caused by poloidal halo currents. The gas-jet species-charge distribution can include >50% fraction neutral species which inhibits runaway electrons. The favorable scaling of this technique to burning fusion plasmas is discussed.

Journal Article↗
PubMed2001

Shape retention in porcine-septal cartilage following Nd:YAG (lambda = 1.32 microm) laser-mediated reshaping.

BACKGROUND AND OBJECTIVE: Photothermal heating of mechanically deformed cartilage accelerates stress relaxation and results in sustained shape change. In this study, shape retention was measured in Nd:YAG laser reshaped porcine septal cartilage. MATERIALS AND METHODS: Specimens were laser reshaped either 4 (Group I) or 28 hours (Group II) following extraction from the crania. Specimens were bent into approximately semicircular shapes and irradiated half way between the endpoints of the semicircle. Resultant bend angle was calculated based on linear measurements. Shape retention was calculated by comparing resultant curvature with pre-irradiation measurements. RESULTS: Mechanical deformation alone resulted in initial bend angles varying from 188 degrees to 229 degrees. Resultant bend angles varied from 84 degrees to 194 degrees corresponding to shape retention varying from 58 to 75%. Non-irradiated cartilage retained less than 46% of the original bend. Shape retention was greater in Group II, compared to Group I. In Group I, no cephalocranial difference in shape retention was observed, though in Group II greater shape retention was observed in rostral specimens. CONCLUSION: While laser heating does significantly reshape cartilage, clinical use of this technology will require "overbending" of the cartilage graft to compensate for this memory effect. The degree of overbending is likely to vary with cartilage type and location.

Animals↗
PubMed2000

Preliminary outcome analysis of a long-term rehabilitation program for severe acquired brain injury.

OBJECTIVES: To describe the general characteristics and functional outcomes of individuals treated in a publicly funded, long-term, acquired brain injury rehabilitation program and investigate variables affecting functional outcomes in this patient population. DESIGN: Retrospective database review of demographic, descriptive, and functional outcome assessment data. SETTING: Publicly funded, comprehensive, multidisciplinary, long-term, residential brain injury rehabilitation program in Alberta, Canada (64 beds). PATIENTS: All rehabilitation patients admitted to and discharged from the brain injury program from February 1991 to March 1999 (n = 349). INTERVENTIONS: Multidisciplinary rehabilitation program. MAIN OUTCOME MEASURES: Demographic and descriptive information included sex, age at admission, type and severity of injury, time from injury to long-term program admission, and length of stay (LOS). Functional outcome information included level of care required at admission and discharge, admission and discharge Rappaport disability rating scale scores, and admission and discharge FIM instrument and Functional Assessment Measure scores for a subset of patients. RESULTS: Fifty-nine percent of the subjects had severe traumatic brain injuries (TBI) and 41% had severe nontraumatic brain injuries (NTBI) of various causes. Mean age at admission was older and LOS was longer for NTBI compared with TBI; there were no other differences between the groups in demographic or descriptive measures. The TBI group had significantly lower admission motor subscale scores than the NTBI group, but the groups did not differ on cognitive scores. All functional assessment measures showed statistically significant improvement from admission to discharge, and 85.6% of patients were discharged to community living after a mean LOS of 359.5 days. Functional status at admission, age at admission, length of time between injury and admission, and LOS in the rehabilitation program significantly correlated with functional improvement. CONCLUSIONS: Patients with severe TBI and NTBI who were not candidates for other more conventional forms of rehabilitation showed significant improvement in functional outcomes after extended program admissions. Consideration was also given to the potential insensitivity of commonly used outcome assessment measures in this population.

Adult↗
PubMed2000

Slow-to-recover severe traumatic brain injury: a review of outcomes and rehabilitation effectiveness.

Severe traumatic brain injury may result in very severe disability with prolonged recovery. Because of this slow recovery, survivors of severe traumatic brain injury may not be considered as good candidates for typical brain injury rehabilitation programmes and, thus, there is relatively little published information concerning the nature of this group. The recent literature regarding functional outcomes and the effectiveness of rehabilitation for this sub-population of brain-injury survivors is reviewed and suggestions for further research are discussed. The existing evidence suggests that this emerging but important group of brain-injury survivors is capable of significant functional recovery over a period of months-to-years after injury, and that rehabilitation may serve to further ameliorate disability and reduce longterm costs of care. It is suggested that further research focus on delineating the nature of recovery in the slow-to-recover brain injury population, exploring the current prevalence of slow-to-recover brain injury survivors, and assessing the effectiveness of currently existing programmes specializing in rehabilitation of this type.

Brain Injuries↗
PubMed1996

Placement of ureteral stents in pregnancy using ultrasound guidance.

Urolithiasis is one of the most common causes of pain in pregnancy. Renal calculi can create a diagnostic and therapeutic challenge; left untreated, they can adversely affect maternal and fetal outcome. Although most cases of obstructive uropathy can be managed conservatively, some require relief of obstruction, usually by placement of a ureteral stent. We describe the use of ultrasound to identify an obstructed collecting system and provide guidance for placement of a double-pigtail ureteral stent in two pregnant patients. The technique used to manipulate the guide wire and stent into the renal pelvis under real-time ultrasound monitoring is discussed.

Adult↗
PubMed1995

The clinical uses of dietary fiber.

Dietary fiber has received considerable attention in both the popular press and the scientific literature. Fiber is a complex mixture of substances, and research on its effects is difficult to interpret. Dietary fiber has significant gastrointestinal effects, and it is a mainstay of treatment for constipation and hemorrhoids. Insoluble fiber, such as wheat bran, is most effective for treatment of these conditions. Increased intake of soluble dietary fiber appears to benefit patients with diabetes mellitus and hyperlipidemia. High-fiber, low-fat diets have been recommended by a variety of authorities to decrease the incidence of heart disease and certain types of cancer. Any increase in dietary fiber intake should be accompanied by an increase in water intake.

Diabetes Mellitus↗
PubMed1993

Body fat and fat distribution by anthropometry and the response to high-fat cholesterol-containing diet in monkeys.

Considerable variability exists among individuals in the response of plasma cholesterol to changes in dietary fat and cholesterol, and obesity is one variable reported to affect this response. This study was performed to determine the relationship between body fat and changes in plasma cholesterol in cynomolgus monkeys fed a high-fat cholesterol-containing diet for 12 months. The animals gained significant body weight (body mass index increased from 30.5 +/- 0.5 to 35.7 +/- 2.8 kg/m2) and skinfold parameters of body fat increased as well. Total cholesterol increased from 109 +/- 4 to 390 +/- 25 mg/dl (P < 0.001), and there were also significant increases in LDL- and HDL-cholesterol and triglyceride. While there was very little relationship between body fat and plasma lipids before the diet, after 12 months, there were significant negative correlations between total and LDL-cholesterol and anthropometric measures of body fat (r ranged from -0.37 to -0.55, P < 0.01). The correlations were not affected when the effects of baseline body mass index and serum cholesterol and total food intake were controlled by partial correlation analysis. In this sample of animals, the acquisition of greater body fat appeared to protect against rises in cholesterol in response to consumption of a high-fat cholesterol-containing diet.

Adipose Tissue↗
PubMed1993

Abdominal obesity is associated with insulin resistance.

BACKGROUND: Recent evidence suggests that insulin resistance and hyperinsulinemia may account for many of the medical complications of obesity. This study was performed to determine whether a predominance of body fat in the abdominal region is associated with insulin resistance and hyperinsulinemia. METHODS: Two groups of nine obese women were matched for age and total obesity but differed significantly in the pattern of fat distribution as defined by the waist-to-hip circumference ratio (WHR). The high-WHR group had a WHR of 0.87 (+/- 0.01), and the low-WHR group had WHR of 0.77 (+/- 0.02) (P < .05). RESULTS: Plasma levels of glucose, free fatty acids, and insulin, measured hourly for eight hours while the subjects consumed a diet of regular food, were higher in the high-WHR group. CONCLUSION: The high-WHR group (abdominal obesity) was more resistant to the action of insulin. These results suggest that measurement of the WHR could help define the degree of medical risk for a given obese patient seeking treatment.

Abdomen↗
PubMed1992

Fluoxetine treatment of the obese diabetic.

Fluoxetine, an inhibitor of serotonin re-uptake, has been shown to cause weight loss in humans and animals. In order to determine the effects in diabetic subjects, 48 male and female, obese, type 2 non-insulin dependent diabetics being treated with insulin were randomized to receive fluoxetine 60 mg or placebo once daily in double blind fashion for 24 weeks. In all subjects, this treatment was preceded by four weeks and followed by six weeks of single blind placebo washout treatment. Subjects performed daily home glucose monitoring and were given instruction in a 1200 kcal American Diabetes Association diet. Fluoxetine treated subjects who completed the trial (n = 16) lost more weight than placebo treated subjects (n = 20) (9.3 +/- 2.4 vs. 1.9 +/- 2.9 kg +/- s.e.m, P less than 0.05). Subjects in the fluoxetine group also showed a greater percentage decrease in insulin dose than those in the placebo group (46.9 +/- 7.6% vs. 19.3 +/- 7.6%, P less than 0.01). During active treatment, the change in serum glucose levels did not differ between the two groups, while glycohemoglobin fell more in fluoxetine treated subjects than in placebo treated subjects at two of four follow-up visits. These results suggest that fluoxetine may be of benefit in the treatment of obese patients with type 2 non-insulin dependent diabetes mellitus.

Adult↗
PubMed1992

A randomized double-blind clinical trial of fluoxetine in obese diabetics.

Fluoxetine is an inhibitor of serotonin re-uptake which has been found to produce weight loss in humans and animals. To test the effects of this drug in obese diabetic subjects, 48 male and female, obese type II non-insulin dependent (NIDDM) diabetics who were being treated with insulin were randomized to receive either fluoxetine 60 mg or a placebo once daily in a randomized double-blind fashion for 24 weeks. A four week single-blind placebo lead-in period preceded and a six week single-blind placebo period followed the double-blind treatment period. Subjects performed daily home glucose monitoring and were given instruction in a 1200kcal American Diabetic Association (ADA) diet. Subjects treated with fluoxetine achieved a maximum 8 kg greater weight loss on average than the placebo-treated subjects. At the end of active treatment, fluoxetine-treated subjects had significantly lower glycohaemoglobin levels than the placebo-treated group (9.72 vs. 10.76%, P < 0.05). In addition, fluoxetine-treated subjects showed a greater decrease in total daily insulin dose than placebo-treated subjects (44.5 vs. 20.1% decrease at the end of active treatment, P < 0.05). These results suggest that fluoxetine may be of benefit in the treatment of obese patients with type II non-insulin dependent diabetes mellitus.

Blood Glucose↗
PubMed1991

Use of relative weight and Body Mass Index for the determination of adiposity.

Relative weight and Body Mass Index (BMI) are commonly used as measures of body fatness in epidemiologic and clinical studies. In order to determine their accuracy, they were compared to body fat measured by underwater weighting and total body water determination in 29 males and 75 females who varied widely in body composition. Relative weights calculated from the Metropolitan Life Insurance Tables correlated so highly with BMI that these measures can be considered to be identical (R2 = 0.992 to 0.999). Linear regression analysis showed a significant correlation between BMI and percentage body fat in men (R2 = 0.68, %fat = 0.99 X BMI -1.32, p less than 0.001) and women (R2 = 0.74, %fat = 0.94 X BMI + 10.77, p less than 0.001). We conclude that relative weight and BMI are nearly identical, and that they are reasonable estimates of body fatness.

Adipose Tissue↗
PubMed1991

The relationship between body fat mass and fat-free mass.

It has been suggested that there is a curvilinear relationship between lean body or fat-free mass and body fat mass. In order to confirm this relationship, body composition was measured by determining body density and total body water using deuterium-labeled water in subjects varying widely in body fat mass. There were 29 males and 75 females with body mass index ranging from 20 to 66 kg/m2. The relationship between fat-free mass and fat mass appeared to be linear over the range of body fat from 10 to 90 kg: males R2 = 0.67 (p less than 0.0001) and females, R2 = 0.47 (p less than 0.0001). The amount of variance explained was not greater when the log of fat mass was used in place of fat mass alone. Multiple regression analysis demonstrated that the relationship between fat-free mass and fat mass remained significant (p less than 0.001) after adjusting for body height, age, and fat distribution. It is concluded that over the range of body fat extending from 10 to 90 kg there is a positive and linear relationship between fat-free body mass and fat mass.

Adipose Tissue↗
PubMed1991

Magnetic-resonance imaging used for determining fat distribution in obesity and diabetes.

Computed-tomography scanning and magnetic-resonance imaging (MRI) have been used to quantify intraabdominal and subcutaneous fat depots. In this study MRI was used to define fat-distribution patterns in 24 obese females with non-insulin-dependent diabetes (NIDDM) and 12 females with simple obesity. Subjects had anthropometric measurements and single-slice abdominal scans performed at the umbilicus. In addition, in 10 of the nondiabetic females, measurements were repeated after 10 wk of a very-low-calorie diet. Nondiabetic females had significantly less intraabdominal fat (P less than 0.01) than did the diabetics but had equivalent subcutaneous fat. There was no significant relationship between waist-to-hip ratio and intraabdominal fat, subcutaneous fat, or their ratio. After a weight loss of 10.6 +/- 3.8 kg there were significant decreases in both intraabdominal and subcutaneous fat (P less than 0.01). Weight loss is associated with decreases in fat in both depots.

Adipose Tissue↗
PubMed1991

Changes in individual plasma free fatty acids in obese females during fasting and refeeding.

In order to determine whether the metabolism of individual free fatty acids is affected by fasting, plasma levels were measured daily in seven obese females during ten days of fasting and four days of refeeding. There was a gradual rise in free fatty acids throughout the fasting period with some variability during the last three days. Free fatty acids remained high during early refeeding followed by a decrease at the end of refeeding. Changes in concentration were most pronounced for oleic (18:1w9) and palmitic (16:0) acids which had the highest initial levels. Expressed as percent change from baseline, oleic, palmitic, and linoleic (18:2w6) acids had similar patterns, while changes were more dramatic for palmitoleic acid (16:1) and less so for stearic acid (18:0) than the others. When expressed as proportion of total free fatty acids, there was very little change in any individual free fatty acid despite the large fluctuations in actual plasma values. It appears that the five major free fatty acids in plasma undergo similar changes during fasting and refeeding, and the palmitic and oleic acids can serve as suitable tracers for metabolic studies.

Adult↗
PubMed1990

Skinfold thickness measurements in obese subjects.

To determine the accuracy of skinfold thickness measurements in body composition assessment, skinfold thicknesses, bioelectrical impedance, body density by underwater weighing, and total body water by deuterium dilution were determined in 105 healthy adults who varied widely in body fatness. Body fat ranged from 2.9% to 61.2% of body weight and a substantial number of obese subjects was included. The correlation between body fat calculated from skinfold equations and body fat measured by underwater weighing was in the same range as that between body fat estimated from impedance and underwater weighing. However, body fat calculated both from skinfold equations and bioelectrical impedance tended to be underestimated compared with body fat calculated from underwater weighing and total body water in the most obese subjects. In obese subjects it was not possible to measure significant numbers of skinfold thicknesses because of the inadequate size of the calipers.

Adult↗