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Biomedical subjects

D Ball

Publications and source records attributed to D Ball.

At least 91 records · Page 5Linked to original sources
PubMed1997

Knowledge and attitudes of teachers towards epilepsy in Zimbabwe.

OBJECTIVE: As a preliminary to designing a health education programme on epilepsy for teachers in Zimbabwe, we evaluated the knowledge and attitudes to epilepsy of teachers in Epworth, a poor, high density suburb of Harare, Zimbabwe. MATERIALS AND METHODS: All teachers in Epworth were invited to awareness workshops on epilepsy. A questionnaire on knowledge and attitude of epilepsy was distributed to all consenting participants. RESULTS: 165 teachers (Male:Female 1:1.9) responded. Of the respondents 89% had heard or read about epilepsy, while 70.6% had observed an epileptic seizure. Epilepsy was considered hereditary by 34.6%, while 12.6% thought it was a form of insanity. Only 0.6% thought evil spirits were a cause, 22.6% thought that epilepsy was contagious, 82% would allow their child to play with an epileptic child, 76% would marry an epileptic while 55.7% would employ an epileptic. The majority would accommodate an epileptic and teach an epileptic child in class. CONCLUSIONS: These positive attitudes towards epilepsy by teachers may be attributed to their higher level of education and may imply that with increasing levels of formal education in the general African population, a more tolerant attitude towards epilepsy can be expected.

Adult↗
PubMed1997

The effect of sodium citrate ingestion on the metabolic response to intense exercise following diet manipulation in man.

Feeding a high-carbohydrate (CHO) diet and administration of alkalinizing agents have both been shown to improve performance in high-intensity exercise. The effect of these treatments in combination was investigated in the present study. Six healthy male subjects exercised to exhaustion on an electrically braked cycle ergometer at a power output equivalent to 100% of their maximum oxygen uptake (VO2,max) on four separate occasions. Each subject consumed either a diet with the same composition as his normal diet (termed the experimental normal (N) diet; 54 +/- 7% CHO, 13 +/- 2% protein, 33 +/- 7% fat) or a high-CHO diet (81 +/- 2% CHO, 13 +/- 2% protein, 6 +/- 1% fat) that had the same energy and protein content for the 3 days prior to the exercise tests. Subjects then ingested either a placebo (CaCO3) or trisodium citrate (0.3 g (kg body mass)-1) 3 h before exercise. Time to fatigue was not different between experimental conditions. Consumption of the high-CHO diet had no effect on blood acid-base status, but the ingestion of sodium citrate induced a mild metabolic alkalosis after both the N diet and the high-CHO diet. This alkalinizing effect was also evident after exercise, since blood pH, plasma bicarbonate and blood base excess were higher (P < 0.05) after the ingestion of sodium citrate than under the placebo conditions. The changes in blood lactate, pyruvate and glucose and plasma glycerol after exercise were similar for all experimental conditions. Blood lactate, glucose and pyruvate and plasma glycerol concentrations increased from resting values (P < 0.01) following exercise but this increase was similar under all experimental conditions. These data demonstrate that when the energy and protein content of the diets is the same, exercise capacity and the metabolic response to intense exercise are similar following consumption either of a high-CHO diet or a more normal diet. Acute ingestion of sodium citrate prior to exercise resulted in a reduction in post-exercise acidosis despite a blood lactate concentration that was similar to that observed after the ingestion of a placebo, but did not affect exercise performance under the conditions of this study.

Acid-Base Equilibrium↗
PubMed1996

The acute reversal of a diet-induced metabolic acidosis does not restore endurance capacity during high-intensity exercise in man.

The present experiment was designed to investigate whether a diet-induced metabolic acidosis was a major factor in the earlier onset of fatigue during high-intensity exercise. Six healthy males cycled to exhaustion at a workload equivalent to 95 percent of maximum oxygen uptake on four separate occasions. Exercise tests were performed after an overnight fast and each test was preceded by one of four experimental conditions. Two experimental diets were designed, either to replicate each subject's own normal diet [N diet, mean (SD) daily energy intake (E) = 13 (0.7) MJ, 14.5 (0.8) percent protein (Pro), 37.5 (2.2) percent fat (Fat) and 47.5 (2.1) percent carbohydrate (CHO)], or a low-carbohydrate diet [E = 12.6 (0.8) MJ, 33.6 (1.3) percent Pro, 64.4 (1.5) percent Fat and 2.2 (0.4) percent CHO]. These diets were prepared and consumed within the department over a 3-day period. Over a 3-period prior to the exercise trial subjects ingested either NaHCO(3) or CaCO(3) (3.6 and 3.0 mmol*kg body mass), thus giving four experimental conditions: N diet and treatment, N diet and placebo, low-CHO diet and treatment and low-CHO diet and placebo. Treatments were assigned using a randomised protocol. Arterialised venous blood samples were taken for the determination of acid-base status and metabolite concentrations at rest prior to exercise and at intervals for 30 min following exhaustion. Consumption of the low-CHO diet induced a mild metabolic acidosis which was reversed by the ingestion of NaHCO(3). Blood pH, bicarbonate (HCO-(3)) and base excess (BE) were higher following NaHCO(3) ingestion after the normal diet than all of the other experimental conditions (P <0.01). Exercise time following the low-CHO diet was less than on the normal diet conditions (P <0.05): bicarbonate ingestion had no effect on exercise time on either of the diet conditions. Post-exercise blood pH, HCO-(3); and BE were higher following the ingestion of NaHCO(3) irrespective of the pre-exercise diet (P <0.05). Blood lactate concentration was higher 2 min after exercise following the N diet with NaHCO(3) when compared to the low-CHO diets with either NaHCO(3) or placebo (P <0.05). Plasma ammonia accumulation was not significantly different between experimental conditions. These data confirm previous data showing that the ingestion of a low-CHO diet reduces the capacity to perform high-intensity exercise, but it appears that the metabolic acidosis induced by the low-CHO diet is not the cause of the reduced exercise capacity observed during high-intensity exercise under these conditions.

Acid-Base Equilibrium↗
PubMed1996

Allelic association between a Ser-9-Gly polymorphism in the dopamine D3 receptor gene and schizophrenia.

We examined a Ser-9-Gly polymorphism in the dopamine D3 receptor gene for allelic association with schizophrenia in 133 patients currently treated with clozapine and 109 controls. Allele 1 (Ser-9) was significantly more frequent in the patients (69%) than in the controls (56%) (P = 0.004). The 1-1 genotype was more common (43% vs 30%) and the 2-2 genotype less common (5% vs 18%) in patients than in controls. When the patient group was subdivided on the basis of clinical response to clozapine, using a 20-point improvement in the global assessment scale as cut-off, genotype 1-1 was found to be more frequent among the non-responders (53% vs 36%, P = 0.04). To place our results in the context of previous studies of this polymorphism and schizophrenia, we performed a meta-analysis of all published data including the present sample. The combined analysis shows evidence for a modest association between genotype 1-1 and schizophrenia (odds ratio 1.25, 95% confidence interval 1.05-1.49, P = 0.01). These results suggest that the Ser-9 allele, or a nearby polymorphism in linkage disequilibrium, results in a small increase in susceptibility to schizophrenia.

Alleles↗
PubMed1996

Radiation treatment of superior sulcus lung carcinoma.

The survival of patients with superior sulcus lung carcinoma and the effects of treatment were reviewed. From a prospective database of 4123 consecutive new patients with lung carcinoma, 131 (3.2%) cases of superior sulcus lung carcinoma were identified. Seventy-four patients were planned to receive radiation with palliative intent, 53 radical radiotherapy and one was observed only. The remaining three patients, with small-cell carcinoma, were treated with chemotherapy with or without radiotherapy. Of the 53 radically treated patients, nine were treated with pre-operative radiation prior to intended radical resection. Analysis was carried out on the effect on survival of performance status, nodal involvement, weight loss, vertebral body or rib involvement, treatment intent and radical combined modality treatment compared with radical radiation alone. The estimated median survival for the whole group was 7.6 months; for those treated radically it was 18.3 months, while for the palliatively treated patients it was 3.7 months. Radically treated patients with no initial nodal involvement had an estimated median survival of 22 months, while radically treated patients with nodal involvement had an estimated median survival of 8.4 months (P = 0.003). There were no statistically significant differences in survival between radically treated patients grouped according to initial weight loss, performance status, or vertebral body and rib involvement. Patients treated with pre-operative radiation did not survive significantly longer than patients treated with radiation alone, although the numbers are small.

Adult↗
PubMed1996

Molecular mechanisms underlying the plasticity of muscle contractile properties with temperature acclimation in the marine fish Myoxocephalus scorpius

Single fibres were isolated from the fast myotomal muscle of the short-horned sculpin (Myoxocephalus scorpius L.). Fish were acclimated to either 5 &deg;C (10 h:14 h light:dark) or 15 &deg;C (12 h:12 h light:dark) for 1&shy;2 months. Isometric tension (Fmax) and unloaded contraction velocity (Vslack) were determined in maximally activated skinned fibres over the range 0 to 20 &deg;C. Fibres isolated from 5 &deg;C-acclimated and 15 &deg;C-acclimated fish failed to relax completely following activations at 15 &deg;C and 20 &deg;C respectively. In 5 &deg;C-acclimated fish, Fmax increased from 75 kN m-2 at 0 &deg;C to 123 kN m-2 at 10 &deg;C and was not significantly higher at 15 or 20 &deg;C. The relationship between Fmax and temperature was not significantly different for cold- and warm-acclimated fish. Vslack was around 2.8 fibre lengths s-1 in both acclimation groups at 0 &deg;C, but it increased at a significantly faster rate with temperature in 15 &deg;C- than in 5 &deg;C-acclimated fish. At 20 &deg;C, Vmax was significantly higher in 15 &deg;C-acclimated (8.7 fibre lengths s-1) than in 5 &deg;C-acclimated fish (5.3 fibre lengths s-1). In order to investigate the molecular mechanism(s) underlying changes in Vmax, myosin was purified by ion-exchange chromatography. No difference in myosin heavy chain composition could be detected on the basis of peptide mapping with four different proteolytic enzymes. Two-dimensional polyacrylamide gel electrophoresis revealed no myofibrillar protein isoforms unique to either acclimation temperature. However, the ratio of myosin alkali light chain contents (LC3f:LC1f), as determined by capillary electrophoresis, was significantly lower in muscle from 15 &deg;C-acclimated (0.73) than from 5 &deg;C-acclimated fish (1.66). The results suggest that changes in Vmax are achieved via altered expression of myosin light chains independently of myosin heavy chain composition. In support of this hypothesis, the myofibrillar ATPase activity of fast muscle was not altered by temperature acclimation.

Journal Article↗
PubMed1996

Graft surveillance and angioplasty prolongs dialysis graft patency.

BACKGROUND: In the United States of America, vascular access complications are the most frequent cause of death among patients with end-stage renal disease on hemodialysis. The majority of American patients with end-stage renal disease have prosthetic grafts for access. The most common complication of prosthetic graft fistulas is thrombosis. To prolong graft life and decrease the frequency of operations, a university-based dialysis unit adopted a policy of graft surveillance by measuring venous resistance, followed by fistulagram and percutaneous dilatation of identified stenoses. The purpose of this retrospective study is to determine if this policy affected graft patency and graft life. STUDY DESIGN: This retrospective review compares outcomes for two years before adoption of this policy (control group, 210 patients) with the outcomes for three years after adoption (study group, 260 patients). Fifty (24 percent) of the control group and 71 (27 percent) of the study group were defined as "complicated" patients because they underwent more than one intervention over any 12-month period. RESULTS: The 50 complicated patients in the control group underwent 104 operations for thrombosis over two years, 1.04 thrombotic episodes and operations per patient year. Seventy new grafts were placed with a mean primary patency of 3.9 months. Mean graft survival time was 6.3 months. The 71 complicated patients in the study group underwent 111 fistulagrams, 80 angioplasties, and 110 operations over three years, for 0.52 thrombotic episodes per patient year (p < .001). Forty-five new grafts were placed with a primary patency of 11.5 months (p < .001). Mean graft survival time was 15.8 months (p < .001). CONCLUSIONS: This retrospective study demonstrates the effectiveness of a policy of graft surveillance and percutaneous treatment of graft stenosis in prolonging primary surgical patency and graft survival.

Angioplasty, Balloon↗
PubMed1995

Association between clozapine response and allelic variation in 5-HT2A receptor gene.

We report allelic association between a polymorphism (T102C) within the coding region of the 5-HT2A gene (HTR2A, 13q14-21) and response to clozapine in schizophrenic patients. Homozygosity for the C102 allele was more frequent (30/57, 53%) among patients who did not respond to clozapine than in those who responded (23/92, 25%). This finding is evidence that allelic variation of genes which encode neurotransmitter receptors can influence clinical response to antipsychotic drugs.

Alleles↗
PubMed1995

A phase III study of accelerated radiotherapy with and without carboplatin in nonsmall cell lung cancer: an interim toxicity analysis of the first 100 patients.

PURPOSE: In 1989 we initiated a multicenter randomized trial to determine if accelerated radiotherapy with or without concurrent carboplatin improves local control and survival in patients with limited nonsmall cell lung cancer. This interim analysis was performed on the first 100 patients to determine whether the toxicity of the four treatment arms is acceptable. METHODS AND MATERIALS: One hundred patients with limited nonsmall cell lung cancer have been randomized to receive one of four treatments: arm I, radiotherapy 60 Gray (Gy) in 30 fractions in 6 weeks; arm II, accelerated radiotherapy 60 Gy in 30 fractions in 3 weeks; arm III, radiotherapy as in arm I plus carboplatin 350 mg/m2 during weeks 1 and 5 of radiotherapy; arm IV, radiotherapy as in arm II plus carboplatin 350 mg/m2 during week 1. Survival was measured for the group as a whole and treatment-related toxicities in the four arms were compared. RESULTS: The estimated median survival for all 100 patients was 17.1 months with 33% estimated survival at 2 years. The major toxicities were hematologic and esophageal. Patients receiving carboplatin had more neutropenia (p < 0.0001) and thrombocytopenia (p = 0.002) than patients receiving radiotherapy alone, and this was most marked in patients on arm III. Both carboplatin and accelerated radiotherapy separately caused more severe esophagitis when compared to conventional radiotherapy alone (p = 0.011 and p = 0.0017, respectively). Esophagitis was more prolonged in patients having accelerated radiotherapy (p < 0.0001, median duration 3.2 months compared with 1.4 months for patients receiving conventional fractionation). Six patients (23%) treated on arm II have required dilatation of esophageal stricture, one dying with a laryngo-esophageal fistula. CONCLUSION: In patients receiving radiotherapy for unresectable lung cancer, overall treatment time can be halved and carboplatin administered concurrently with increased but acceptable esophageal and hematologic toxicity.

Adult↗
PubMed1995

Survival following radiotherapy for post-surgical locoregional recurrence of non-small cell lung cancer.

Long term survival [> 3 years] has been documented in patients treated with radiotherapy for bronchial stump recurrence following surgery for non-small cell lung cancer [NSCLC]. In this retrospective review of 45 patients with locoregional recurrence of NSCLC we measured survival following radiotherapy according to site of recurrence [bronchial stump or elsewhere] and treatment intent. Estimated median survival for all 45 patients from presentation was 10 months. Ten patients whose disease was confined to the bronchial stump had an estimated median survival of 15 months compared with 9 months for patients with recurrence elsewhere [P = 0.4]. Seventeen patients treated with radical intent [dose > 50 Gy] had an estimated median survival of 16 months, with an estimated 41% alive at two years. The overall survival of patients treated with radical intent is not dissimilar to that of a group of our patients treated similarly with primary radiotherapy for inoperable NSCLC. We conclude that a policy of high dose radiotherapy may be justified in selected patients with recurrent NSCLC.

Adult↗
PubMed1995

Correlation of venography, venous pressure, and hemoaccess function.

We analyzed the anatomic features of both grafts and fistulas and correlated these features with access function. We also attempted to determine venous pressures predicting access dysfunction (critical venous pressures) at various blood flow rates (BFRs). Therefore, accesses of 46 chronic hemodialysis patients were studied by venography in a prospective fashion. We defined the incidences of various lesions and the effects of venous collaterals on graft function, and determined critical venous pressures at various BFRs. Eighty-three percent of the accesses had outflow obstruction. Five types of anatomic lesions were identified. The incidences were venous stenosis of the draining vein immediately proximal to the venous anastomosis, 36.4%; central vein, 23.6%; venous anastomosis, 25.5%; arterial anastomosis, 10.9%; and intragraft hyperplasia, 3.6%. Twelve patients had multiple lesions. When the homogenous polytetrafluoroethylene arm graft population was studied for the effect of venous collaterals, we found that venous collaterals conferred protection but did not prevent graft failure. Venous pressure measurements were good predictors of access failure at the lower BFRs. Venous pressures increased with increasing BFRs. A critical venous pressure of 145 mm Hg was found for a BFR of 250 mL/min. At a BFR of 300 mL/min, the critical venous pressure was 170 mm Hg. A critical venous pressure could not be found for a BFR of 400 mL/min.

Arteriovenous Shunt, Surgical↗