PubMed Health⌕ Search

Biomedical subjects

J H Stewart

Publications and source records attributed to J H Stewart.

At least 19 recordsLinked to original sources
PubMed1992

Risk factors for kidney cancer in New South Wales, Australia. II. Urologic disease, hypertension, obesity, and hormonal factors.

In a population-based case-control study of kidney cancer in New South Wales, Australia, data from structured interviews with 489 cases of renal cell cancer (RCC) and 147 cases of renal pelvic cancer (CaRP) diagnosed in 1989 and 1990, and 523 controls from the electoral rolls, confirmed the link between obesity and RCC. In addition, regular consumption of 'diet' pills independently increased the risk for this cancer. A diagnosis of hypertension at least two years before interview raised the risk for RCC, and regular use of beta-blockers, a class of antihypertensive drug, independently increased the risk for RCC and CaRP (risk ratio = 1.5-1.8). No independent effect was found for use of diuretics. Additional information provided by this study includes increased risks associated with kidney injury (RCC, CaRP)--possibly attributed to recall bias--and kidney infection (CaRP), as well as a nonsignificantly raised risk linked with kidney stones (RCC, CaRP) and a significantly reduced risk for RCC in persons giving a history of lower urinary tract infection. No significant association of RCC was found with hormonal factors (age at menarche or menopause; child-bearing; regular use of oral contraceptives or estrogens; hysterectomy or oophorectomy).

Adult↗
PubMed1992

Risk factors for kidney cancer in New South Wales--I. Cigarette smoking.

In a population-based case-control study of kidney cancer in New South Wales, data from structured interviews with 489 cases of renal cell cancer (RCC), 147 cases of renal pelvic cancer (CaRP) diagnosed in 1989 and 1990, and 523 controls from the electoral rolls confirmed an increased risk associated with cigarette smoking in both types of cancer. The risk among current smokers was consistently higher than among ex-smokers, and was nearly twice as great for CaRP than for RCC. Additional information provided by this study includes reduced risks following cessation of smoking within 12 years for CaRP, but only after 25 years for RCC. Starting to smoke before, rather than after, the age of 18 years is linked independently with almost twice the risk for CaRP, but does not affect the risk for RCC. No independent trend was found with number of cigarettes smoked per day.

Adult↗
PubMed1992

Understanding vascular ultrasonography.

The technology of imaging has progressed rapidly; thus, physicians must stay abreast of the principles of utilization and the interpretation of these new tests. Most of the information about this technology is presented in subspecialty literature that is not readily accessible or easily interpretable by nonspecialists. Herein we review the current literature on vascular ultrasonography and present the information in a simple, practical manner. The safety, utility, and accuracy of the ultrasound devices are delineated for the study of various vascular conditions.

Blood Vessels↗
PubMed1992

Theophylline and salbutamol improve pulmonary function in patients with irreversible chronic obstructive pulmonary disease.

To investigate the efficacy of bronchodilators in patients with irreversible chronic obstructive pulmonary disease (COPD), we conducted a double-blind, randomized, four-phase, crossover comparison between placebo, oral theophylline, inhaled salbutamol, and a combination of both drugs in 12 patients with stable COPD (mean age, 63 years) whose increase in forced expiratory volume in 1 s (FEV1) was less than or equal to 15 percent following 200 micrograms of inhaled salbutamol. Patients received two weeks of therapy with each of the test regimens. Both theophylline and salbutamol resulted in statistically significant improvement in FEV1, forced vital capacity (FVC), slow vital capacity (SVC), residual volume (RV), airway resistance (Raw), and maximum expiratory flow rate at 50 percent of vital capacity (V50). In most instances, there were no significant differences between theophylline and salbutamol. Combination therapy produced significantly greater improvement in FEV1, FVC, V50, Raw, and RV than either agent alone. The two drugs interacted in an additive fashion. Neither of the drugs, used singly, significantly reduced the severity or incidence of symptoms. The reduction in dyspnea and wheeze during combination therapy approached statistical significance (p = 0.06) and patient preference was significantly in favor of the combination regimen. None of the active treatments produced significantly more side effects than placebo. We conclude that theophylline and inhaled salbutamol produce significant, and approximately equal, improvement in pulmonary function in patients traditionally classified as suffering from "irreversible" COPD. The combination of theophylline and inhaled salbutamol generally results in additional improvement over that obtained with either drug used alone and this improvement is reflected by reduced symptomatology and treatment preference.

Administration, Inhalation↗
PubMed1991

Sexing of human clavicles using length and circumference measurements.

Measurement of clavicular length and circumference, and computation of clavicular robustness and length-circumference product from 724 autopsied adults of known age, sex, and body length between the ages of 15 and 96 years produced useful sex-predictive values. This predominantly North American white population contained 560 males and 164 females with intact, nondeformed clavicles. Clavicle length and circumference and particularly their product have been found useful in sexing, but robustness as a single trait has not. Despite a significant overlap of male and female values, the use of single cutoff values allowed correct sex assignment of up to 93% of the entire study population, including 94% of males and 89% of females. The ratios of body length to clavicle circumference and to clavicle length are on average greater in women than in men. The former ratio yields male predictive values greater than 95% for those individuals with ratios falling below the cutoff value of 43, whereas the latter ratio is a relatively poor sex predictor.

Adolescent↗
PubMed1991

Low dose erythropoietin in maintenance haemodialysis: improvement in quality of life and reduction in true cost of haemodialysis.

Human recombinant erythropoietin (r-HuEPO) improves quality of life in patients on maintenance haemodialysis, but the haemoglobin (Hb) level necessary to achieve this improvement is unknown. In this study, quality of life, functional capacity and symptoms of 28 haemodialysis patients with an initial Hb of 67 +/- 2 (mean +/- SEM) g/L were assessed after 0, 6 and 12 months of r-HuEPO, the dose of which was titrated to achieve a stable Hb of between 90 and 100 g/L. At six and 12 months Hb was 97 +/- 2 and 93 +/- 2 g/L, and mean r-HuEPO dose between three and six, and between nine and 12 months was 88 +/- 6 and 62 +/- 9 U/kg/week intravenously respectively. There was a significant improvement in level of activity and satisfaction with various aspects of life, and a reduction in fatigue, weakness, dyspnoea, angina and restless legs. Patients were able to walk 50% further in six minutes. The improvement in quality of life and function was similar to that reported from other centres whose target Hb was between 100 and 120 g/L, and where the r-HuEPO dose was 75% higher than in this study. Costs of r-HuEPO therapy were assessed. The drug itself costs +A3681/yr/patient, to which was added the estimated cost of additional dialyses and medications, bringing the total to +A5177/yr/patient. There was, however, a reduction in both hospitalisation by 8.3 days/yr/patient and medical consultation by 3.9 hours/yr/patient. Five patients commenced full-time work, one took up full-time study aimed at finding work, three transferred to home haemodialysis and six fewer patients drew social security benefits. The net cost saving from using low dose r-HuEPO was more than +A1,000/yr/patient.

Adult↗
PubMed1991

Desferrioxamine enhances the haemopoietic response to erythropoietin, but adverse events are common.

To determine whether the chelation of aluminium enhances the haemopoietic response to recombinant human erythropoietin (r-HuEPO), desferrioxamine (DFO) at a dose of 20-30 mg/kg was given to 7 of 17 transfusion-dependent haemodialysis patients treated with r-HuEPO (40 units/kg/dialysis i.v.). The two randomly allocated groups did not differ in age, initial haemoglobin, plasma aluminium, plasma aluminium after DFO challenge, and ferritin, but, by chance, dialysis time was longer in the DFO group (69 vs. 32 months; p = 0.02). DFO was administered for 16 +/- 4 (SE) dialyses. During this period, Hb rose faster in the DFO group, in relation to time (0.61 vs. 0.29 g/l day; p less than 0.05) and r-HuEPO dose (3.35 vs. 1.88 g/l/100 units r-HuEPO/kg; p less than 0.05). However, in the DFO group, there was a high incidence of side effects, especially visual toxicity. It is concluded that DFO enhances the effectiveness of r-HuEPO in correcting the anaemia of chronic renal failure, but the combination of DFO and r-HuEPO is unsafe under the conditions described.

Adult↗
PubMed1991

Repeated dosing of Uniphyl tablets under fed and fasting conditions: comparison of serum theophylline levels, pulmonary function, and asthma symptoms.

In order to determine the effects of repeated administration under fed and fasting conditions on the bioavailability and clinical efficacy of Uniphyl tablets, 22 adult asthmatics took the drug immediately following their evening meal for seven consecutive days and under fasting conditions for an additional seven consecutive days. For each patient, the daily theophylline dose remained constant throughout the study. Peak and trough serum theophylline concentrations (STC), spirometry, asthma symptoms, side effects and use of beta-agonist inhalers were recorded daily at 0730 and 1900 hours. The mean daily theophylline dose was 818.2 +/- 213.0 mg. The mean peak STC when Uniphyl was taken with food was 14.4 +/- 4.5 mg/L and was 13.1 +/- 3.6 mg/L when taken under fasting conditions (P less than .05). The trough STC was 7.4 +/- 2.8 mg/L with food and 6.9 +/- 2.1 mg/L while fasting (NS). There were no significant differences between the two dosing conditions in terms of spirometry, asthma symptom scores, side effects or use of beta-agonist inhalers. There was no significant difference between the patients' morning and evening FEV1 under either dosing condition. Since the differences in STC between fed and fasting conditions were not clinically significant, we conclude that there is no need to restrict patients to a rigid relationship between Uniphyl dosing and meal conditions. On the basis of patient preference and compatibility with a normal lifestyle, we recommend that patients should generally be instructed to take the drug with or shortly following their evening meal.

Aged↗
PubMed1990

Geographical distribution of cancers of the kidney and urinary tract and analgesic nephropathy in Australia and New Zealand.

Age-standardised incidence rates for cancers of the renal parenchyma, renal pelvis and bladder and for end-stage renal failure due to analgesic nephropathy for the years 1982-83 were compared between the Australian states and New Zealand, and within New South Wales (NSW), to determine whether these rates paralleled the previous prevalence of consumption of phenacetin-containing analgesics. Whereas little variation was seen within Australasia in respect of the incidence of cancer of the renal parenchyma and bladder, both cancer of the renal pelvis and end-stage renal failure due to analgesic nephropathy had higher incidence rates amongst women in NSW and Queensland than in the other states or New Zealand. Within NSW, the average annual incidence rates during 1973-82 for renal pelvic cancer in the Hunter region of 1.3 (m) and 1.6 (f) per 100,000 were the highest in the state. These high incidence rates coincided with areas known to have had a high prevalence of consumption of compound analgesics containing phenacetin. In an international comparison with populations which had published incidence rates for each of the periods 1973-77 and 1978-82, the rate for cancer of the renal pelvis in women was highest in both time periods in NSW and had increased absolutely at a faster rate.

Adolescent↗
PubMed1990

Neutralized lidocaine with epinephrine for local anesthesia--II.

The pain usually associated with intradermal injection of lidocaine and epinephrine is significantly attenuated by the addition of either sodium bicarbonate or sodium hydroxide to 1% lidocaine with epinephrine. This suggests that sodium bicarbonate attenuates pain by increasing the pH of the anesthetic solution. The clinical effects of a solution of lidocaine (1%) with epinephrine (1:100,000) and sodium bicarbonate (80 meq/L) were assessed after infiltration in skin. Anesthetic stored for 1 week caused nearly equal areas of anesthesia and vasoconstriction as an identical solution prepared on the day of use.

Anesthesia, Local↗
PubMed1990

The distribution of ventilation-perfusion ratios in the lungs of a dysmature foal.

The distribution of ventilation-perfusion (VA/Q) ratios, before and after 100 per cent oxygen, was studied in an induced-premature foal at 4 h and again at eleven days of age, using the multiple inert gas elimination technique. The major finding was an absence of low VA/Q ratios when breathing air, indicating that low PaO2 in the neonatal period was totally attributable to the right-to-left shunt. At 4 h of age the PaO2 was 5.48 kPa and the right-to-left shunt represented 33.4 per cent of the cardiac output. At eleven days of age the PaO2 was 9.76 kPa and right-to-left shunt was 10.1 per cent of cardiac output. At both ages there was a separate high mode where ventilation was greatly in excess of blood flow but at neither age were units with low VA/Q ratios present. Oxygen breathing for 40 mins did not increase the right-to-left shunt, but at eleven days right-to-left shunt decreased when 100 per cent oxygen was administered.

Acid-Base Equilibrium↗
PubMed1989

Pharmacokinetics and clinical efficacy of oral morphine solution and controlled-release morphine tablets in cancer patients.

Twenty-three adult patients with chronic pain due to cancer completed a double-blind, randomized, two-phase crossover trial comparing plasma morphine concentrations and analgesic efficacy of oral morphine sulfate solution (MSS) and controlled-release morphine sulfate tablets (MS Contin [MSC], Purdue Frederick, Inc., Toronto, Ontario, Canada). MS Contin was given every 12 hours to all patients except those whose daily morphine dose could not be equally divided into two 12-hour doses with the tablet strengths available. MSS was given every 4 hours. Patients received both of the test drugs for at least 5 days, and, on the final day of each phase, peripheral venous blood samples for morphine analysis were obtained. Eighteen patients received MSC every 12 hours, and five received it every 8 hours. The same total daily morphine dose was given in both phases. In the 18 patients who received MSC every 12 hours, the daily morphine dose was 183.9 +/- 140.0 mg (mean +/- SD). In this group, the mean area under the curve (AUC) with MSC was 443.6 +/- 348.4 ng/ml/hour, compared with 406.8 +/- 259.7 ng/ml/hour for MSS (P greater than 0.20). Mean maximum morphine concentrations (Cmax) for MSC and MSS were 67.9 +/- 42.1 and 58.8 +/- 30.3 ng/ml, respectively (P greater than 0.05). Mean minimum morphine concentrations (Cmin) were 17.0 +/- 17.7 and 18.3 +/- 15.0, respectively (P greater than 0.30). There was a significant difference (P less than 0.001) between the two drugs in time required to reach maximum morphine concentration (Tmax). Mean Tmax after MSC occurred at 3.6 +/- 2.3 hours. After MSS, it occurred at 1.3 +/- 0.4 hours. In the five patients who received MSC every 8 hours, the findings paralleled those in the principal group, with no significant differences between MSC and MSS in Cmax or Cmin and a highly significant difference between the two in Tmax. However, in this small group of patients, the AUC with MSC was significantly (P = 0.04) greater than that with MSS. All patients had very good pain control throughout the study and both formulations were well tolerated. There were no significant differences between MSC and MSS in pain scores or side effects. Under the conditions of this study there was no clinically significant difference in bioavailability between MSC and oral MSS. When given on a 12-hourly basis in individually titrated doses, the MSC provided therapeutic plasma morphine concentrations throughout the dosing interval.

Administration, Oral↗