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Biomedical subjects

A Garg

Publications and source records attributed to A Garg.

At least 181 records · Page 10Linked to original sources
PubMed1991

Reducing risk for back pain in nursing personnel.

Transferring the clients from toilet to wheelchair was the task ranked as most stressful by nursing assistants in a nursing home. The compressive force to the L5S1 disc by client weight during the toilet to wheelchair transfer exceeded the action limit permitted as safe by NIOSH. Two of the three mechanical hoists were perceived to be as stressful or more stressful than the moment transfer methods with the walking belt. Of the five manual methods for transferring, the use of the walking belt was determined to be least stressful and most comfortable for nursing subjects and clients.

Accidents, Occupational↗
PubMed1991

Range of motion in total knee arthroplasty. A computer analysis.

A three-dimensional computer model of the knee was formulated based on sectional and coordinate data from knee specimens. The model was consistent with published data in terms of contact points and ligament length patterns. Prosthetic components were designed, and surgical placement was simulated. Maximum flexion was limited by tension in the posterior cruciate ligament. Increased dishing of the tibial surface reduced flexion, but some dishing was considered necessary for reduction of contact stresses. Anteroposterior translation of the tibial component had little effect on flexion. Femoral translation had some offset, and posterior positioning reduced flexion. The most important surgical variable was tibial component tilt in the sagittal plane. Posterior tilt increased motion, while anterior tilt decreased motion. The results apply to the choice of total knee system, instrument design, and surgical technique.

Computer Simulation↗
PubMed1990

Use of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors in various forms of dyslipidemia.

The inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase are highly effective in treating severe elevations of serum cholesterol, and are being widely used for this purpose. In our laboratory, these drugs have been used for the treatment of other forms of dyslipidemia including primary moderate hypercholesterolemia, primary mixed hyperlipidemia, diabetic dyslipidemia, hyperlipidemia of the nephrotic syndrome, and primary hypoalphalipoproteinemia. In these conditions, the HMG CoA reductase inhibitors proved effective in substantially decreasing levels of both low-density lipoproteins and very low density lipoproteins, as well as apolipoprotein B. In some patients, they may even increase levels of high-density lipoproteins. The primary mode of action of HMG CoA reductase inhibitors appears to be to increase the synthesis of hepatic receptors for lipoproteins containing apolipoprotein B, although a reduction in synthesis of these lipoproteins has not been ruled out with certainty. Regardless of mechanisms, drugs of this type appear to have the potential for effective therapy of various forms of dyslipidemia beyond primary severe hypercholesterolemia.

Diabetes Mellitus, Type 2↗
PubMed1990

Nicotinic acid as therapy for dyslipidemia in non-insulin-dependent diabetes mellitus.

Recently, nicotinic acid has been recommended as a first-line hypolipidemic drug. To determine the effectiveness of nicotinic acid in dyslipidemic patients with non-insulin-dependent diabetes mellitus, 13 patients were treated in a randomized crossover trial. Patients received either nicotinic acid (1.5 g three times daily) or no therapy (control period) for 8 weeks each. Compared with the control period, nicotinic acid therapy reduced the plasma total cholesterol level by 24%, plasma triglyceride level by 45%, very-low-density lipoprotein cholesterol level by 58%, and low-density lipoprotein cholesterol level by 15%, and it increased the high-density lipoprotein cholesterol level by 34%. However, nicotinic acid therapy resulted in the deterioration of glycemic control, as evidenced by a 16% increase in mean plasma glucose concentrations, a 21% increase in glycosylated hemoglobin levels, and the induction of marked glycosuria in some patients. Furthermore, a consistent increase in plasma uric acid levels was observed. Therefore, despite improvement in lipid and lipoprotein concentrations, because of worsening hyperglycemia and the development of hyperuricemia, nicotinic acid must be used with caution in patients with non-insulin-dependent diabetes mellitus with dyslipidemia. We suggest that the drug not be used as a first-line hypolipidemic drug in patients with non-insulin-dependent diabetes mellitus.

Aged↗
PubMed1990

Doppler assessment of interventricular pressure gradient across isolated ventricular septal defect.

Continuous wave Doppler ultrasound was used to estimate the pressure gradient between the right and left ventricle for assessment of pulmonary arterial systolic pressure in 30 patients with isolated ventricular septal defect and for subsequent comparison with similar data obtained on cardiac catheterization. The age of the patients ranged from 8 months to 45 years (6.8 +/- 8.6 years). No patient had right or left ventricular outflow tract obstruction. Doppler measurements were done within 24 h of cardiac catheterization. Pressure gradient across ventricular septal defect on cardiac catheterization ranged from 7 to 95 mmHg (48 +/- 24 mmHg) and that on Doppler assessment ranged from 8 to 78 mmHg (42 +/- 20 mmHg). Doppler measurements of interventricular pressure gradient correlated well with those obtained on cardiac catheterization (r = 0.90, p less than 0.001). Correlation was better in patients with pressure gradient across ventricular septal defect less than 75 mmHg (r = 0.96). Correlation was poor in three of five patients with very small ventricular septal defects (interventricular pressure gradient greater than 75 mmHg) because the jet used was not ideal. Thus continuous wave Doppler ultrasound is an accurate noninvasive means of measuring pressure gradient across ventricular septal defect, which is a useful parameter for assessment of pulmonary artery systolic pressure in patients with isolated ventricular septal defect without right and left ventricular outflow tract obstruction.

Adolescent↗
PubMed1990

Prediction of total knee motion using a three-dimensional computer-graphics model.

Twenty-three knees were sectioned, digitized, and standardized to determine the 'average' three-dimensional bony geometry and ligamentous attachments. Data on normal knee motion were obtained from a cadaveric study. An algorithm was written to simulate three-dimensional patella motion. Verification of the knee model was achieved by determining femoro-tibial and patello-femoral contact locations, as well as ligament length patterns, and comparing the results with published data. The criterion for maximum predicted knee motion with a prosthesis in place was the length of the posterior cruciate ligament. Three total knee replacement surfaces were mathematically generated: flat, laxity and conforming. A greater flexion angle was obtained with a flat tibial surface than for the laxity or conforming. Posterior tibial component displacement increased the range of motion, but only slightly. For all tibial surfaces, increased range of motion was achieved with a 10 degrees posterior tilt of the tibial tray. Anterior femoral component displacement increased motion due to reduction in posterior cruciate tension during flexion. The results are applicable to the design and surgical technique of total knee replacement.

Algorithms↗
PubMed1990

Effects of dietary carbohydrates on metabolism of calcium and other minerals in normal subjects and patients with noninsulin-dependent diabetes mellitus.

Transient hypercalciuria has been noted after high carbohydrate meals which is independent of dietary calcium and is probably due to impaired renal calcium reabsorption mediated by an increase in plasma insulin levels. Based on these observations, some investigators believe that long term intake of high carbohydrate diets may increase the risk of nephrolithiasis and possibly osteoporosis. Using a randomized cross-over design, we compared high carbohydrate diets (60% carbohydrate and 25% fat) with high fat diets (50% fat and 35% carbohydrate) for effects on metabolism of calcium and other minerals in eight normal subjects and eight euglycemic patients with noninsulin-dependent diabetes mellitus. All other dietary constituents, such as protein, fiber, fluid, minerals (including Ca, Mg, Na, K, and P), and caffeine intake, were kept constant. Despite higher daylong levels of plasma insulin on the high carbohydrate diets compared to the high fat diet in both normal and noninsulin-dependent diabetic subjects, no changes in daily urinary excretion of calcium or other constituents, associated with renal stone risk, were observed. Furthermore, there was no change in fractional intestinal 47Ca absorption. Although hypercalciuria may ensue transiently after high carbohydrate meals, we conclude that substitution of simple or complex carbohydrates for fats in an isocaloric manner for a longer duration does not result in significant urinary calcium loss, and therefore, high intakes of digestible carbohydrates may not increase the risk of nephrolithiasis or osteoporosis via this mechanism.

Adult↗
PubMed1990

Management of dyslipidemia in NIDDM.

Coronary heart disease is the leading cause of death among patients with non-insulin-dependent diabetes mellitus (NIDDM). NIDDM patients have a high frequency of dyslipidemia, which along with obesity, hypertension, and hyperglycemia may contribute significantly to accelerated coronary atherosclerosis. Because risk factors for coronary heart disease are additive and perhaps multiplicative, even mild degrees of dyslipidemia may enhance coronary heart disease risk. Therefore, therapeutic strategies for management of NIDDM should give equal emphasis to controlling hyperglycemia and dyslipidemia. The National Cholesterol Education Program recently issued guidelines for treatment of hyperlipidemia in adults including diabetic patients. Because of the unique features of diabetic dyslipidemia, however, we suggest that certain modifications in these guidelines be made to meet specific needs of diabetic patients. For example, therapeutic goals for serum cholesterol reduction should be lower in diabetic patients than in nondiabetic subjects. Particular emphasis should be given to weight reduction in NIDDM patients. In some diabetic patients, monounsaturated fatty acids may be a better replacement for saturated fatty acids than carbohydrates. The target for cholesterol lowering should include both very-low-density lipoprotein and low-density lipoprotein (LDL) (non-high-density lipoprotein) rather than LDL alone. To obtain a substantial reduction of cholesterol levels, drug therapy may be required in many patients. However, first-line drugs for nondiabetic patients (nicotinic acid and bile acid sequestrants) may be less desirable in NIDDM patients than hydroxymethylglutaryl coenzyme A (HMG CoA) reductase inhibitors and even fibric acids. In fact, HMG CoA reductase inhibitors may be the drugs of choice for NIDDM patients with elevated LDL cholesterol and borderline hypertriglyceridemia, whereas gemfibrozil appears preferable for NIDDM patients with severe hypertriglyceridemia.

Coronary Disease↗
PubMed1989

An evaluation of the NIOSH guidelines for manual lifting, with special reference to horizontal distance.

A laboratory study was conducted to determine the percentage of subjects capable of lifting loads at the maximum permissible limit (MPL) and the corresponding energy expenditure, heart rate, compressive force on the L5/S1 disc, and ratings of perceived exertion. A second objective was to compare MPLs based on measured horizontal distances with those based on the rule of thumb proposed in the National Institute for Occupational Safety and Health (NIOSH) guide (H = 15 + w/2 cm). Thirteen male subjects were required to lift three different boxes (25, 38, and 51 cm wide) at four different frequencies (0.2, 3, 6, and 9 lifts/min) and at two heights (floor level to bench height [0.8 m] and bench height to 1.5 m). Each lift was performed for 1 hr, and horizontal distances for all 13 subjects were measured at the origin of the lifts. MPLs were computed for all lifting tasks. A psychophysical method was used to determine the maximum acceptable weight of a lift. This weight, however, was not allowed to exceed the corresponding MPL. Maximum acceptable weights for all 13 subjects were equal to the MPLs. Of 13 subjects, 9 indicated that they could lift weights significantly greater than the MPLs. MPLs for the bench to 1.5-m height were significantly greater than the corresponding MPLs for the floor to 0.8-m height. The mean heart rate for 1-hr lifting tasks ranged from 104 to 114 beats/min. The estimated compressive force on the L5/S1 disc ranged from 340 to 598 kg. The mean ratings of perceived exertion for floor level to bench height and bench height to 1.5-m lifts were 12 and 9.6 for the back and 9.3 and 13 for the shoulder, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Natural environment surpasses polluted environment in inducing DNA damage in fish.

Measurement of specific DNA adduct concentrations in target tissues of organisms may provide a key biologic end-point of exposure to environmental carcinogens. Using a general and highly sensitive assay with 32-P-postlabeling, we found that natural populations of freshwater fish species chub, barbel, bream and carp, as well as a marine fish mugil, revealed the presence of four to nine qualitatively similar adducts irrespective of whether they were caught from unpolluted or polluted waters. No statistically significant differences were observed between the adduct levels of fish from the unpolluted waters and those of fish from the polluted waters. A dominant feature of the fish DNA adducts was a species specificity. The finding that a vast majority of DNA modifications in fish are caused by natural factors rather than man-made chemicals offers a basis for a more realistic view in assessing the genotoxic risks in any aquatic environment.

Animals↗
PubMed1989

Gemfibrozil alone and in combination with lovastatin for treatment of hypertriglyceridemia in NIDDM.

Hypertriglyceridemic patients with non-insulin-dependent diabetes mellitus (NIDDM) have an increased risk of coronary heart disease (CHD) and acute pancreatitis. To examine the potential of hypolipidemic drugs for therapy of lipoprotein abnormalities in NIDDM, 10 patients maintaining marked (plasma triglycerides greater than 500 mg/dl) and 6 with moderate (plasma triglycerides 250-500 mg/dl) hypertriglyceridemia, despite good glycemic control, were studied in two phases. In the first phase, gemfibrozil alone (600 mg twice daily) was compared with a placebo, and in the second phase a combination of gemfibrozil and lovastatin (20 mg twice daily) was compared with gemfibrozil alone in a randomized, double-blind, placebo-controlled crossover study. In markedly hypertriglyceridemic patients, gemfibrozil reduced plasma triglycerides by 52% and very-low-density lipoprotein cholesterol (VLDL-chol) by 55% and increased high-density lipoprotein cholesterol by 23% compared with a placebo. However, low-density lipoprotein cholesterol (LDL-chol) levels increased (42%), and LDL apolipoprotein B (apoB) levels remained unchanged. Addition of lovastatin to gemfibrozil effectively reduced total cholesterol (25%), LDL-chol (30%), and LDL-apoB (19%). Lovastatin further reduced plasma triglycerides (11%) and VLDL-chol (27%). However, in moderately hypertriglyceridemic patients, gemfibrozil or the combination therapy did not seem to offer benefits over the previously reported study with lovastatin alone. Glycemic control was maintained throughout the study. In conclusion, the beneficial effects of the combination therapy on lipoprotein levels in markedly hypertriglyceridemic NIDDM patients could decrease the risk of development of both acute pancreatitis and CHD.

Adult↗
PubMed1989

Effect of knee component alignment on tibial load distribution with clinical correlation.

To determine ideal alignment and component placement of total knee prostheses, Kinematic (K) and total condylar (TC) devices were physiologically loaded and interface forces were measured. Laboratory observations were correlated with clinical (roentgenographic) findings. Asymmetric loading of the tibial component has been proposed as causing loosening and radiolucent lines. Misalignment of components is one factor that affects load sharing by bone under the medial and lateral regions of the tibial plateau. Tibial components of K and TC prostheses were inserted without cement into the cut surfaces of artificial tibiae. The mating femoral condylar components were mounted. The tibial and femoral components were individually positioned at 0 degrees (horizontal) and at certain angles of varus and valgus. Pressure-sensitive film was placed between the tibial component and the artificial tibia. A vertical load of 1500 N was used. The experiment was replicated twice. The percentages of the load on the medial and lateral regions of the tibial plateau were calculated from quantitative image analysis of the pressure patterns on the film. Roentgenograms from 532 K and 21 TC patients were examined to determine the orientations of the condylar and tibial components and the presence of radiolucent lines around the tibial component. An even distribution (ideal alignment) of load on the medial and lateral regions of the K tibial component occurred at 9 degrees of valgus tilt of the femoral component and 2 degrees of varus tilt of the tibial component and for the TC at 7 degrees valgus and 0 degrees varus. Misalignment by 5 degrees yielded a 7% change in the load distribution under the K plateau and a 40% change for the TC prosthesis; a 10 degrees misalignment produced changes of 34% and 62% for the K and TC, respectively. Small variations in clinical knee alignment produced the same percentage of radiolucent lines for each alignment group. The location of radiolucent lines was distributed among the medial, lateral, and both tibial plateaus regardless of knee alignment, although there were more medial reactions overall. The smallest incidence (8%) of radiolucent lines occurred with the K prosthesis at 7 degrees of knee valgus, the femoral component placed at 9 degrees valgus, and the tibial component at 2 degrees varus. This correlated with the ideal bench-test findings for the K device.

Humans↗
PubMed1988

Treatment of dyslipidemia in non-insulin-dependent diabetes mellitus with lovastatin.

Coronary artery disease (CAD) is the leading cause of death among whites with non-insulin-dependent diabetes mellitus (NIDDM). Several risk factors--dyslipidemia induced by NIDDM, obesity, hypertension and hyperglycemia--likely contribute to accelerated atherosclerosis. The dyslipidemia in NIDDM is characterized by abnormalities in composition and metabolism of very low density lipoproteins, low-density lipoproteins (LDL) and high-density lipoproteins (HDL). However, because of the lack of long-term prospective epidemiologic studies, the relative importance of lipoprotein risk factors in the causation of CAD in diabetic patients is not clear. The World Health Organization Multinational Study of vascular disease in diabetics observed increased prevalence of CAD in diabetic populations with relatively high levels of plasma cholesterol and supports the concept that lowering cholesterol levels may significantly reduce coronary risk in NIDDM. To determine the effectiveness of lovastatin, an inhibitor of HMG CoA reductase, for lowering cholesterol levels, 16 patients with NIDDM and mild to moderate increases in plasma cholesterol were given lovastatin (20 mg twice daily) in a randomized, double-blind, placebo-controlled manner for 4 weeks. Compared with the placebo, lovastatin reduced concentrations of total cholesterol (233 +/- 10 vs 172 +/- 7 mg/dl [standard error of the mean], p less than 0.001), LDL cholesterol (140 +/- 9 vs 101 +/- 6 mg/dl, p less than 0.001), and LDL apolipoprotein-B (108 +/- 16 vs 80 +/- 16 mg/dl, p less than 0.001). Plasma triglycerides and very low density lipoprotein cholesterol levels also decreased by 31 and 42%, respectively. Although HDL cholesterol levels did not increase, the total cholesterol/HDL cholesterol ratio decreased significantly with lovastatin therapy. No adverse effects were noted and glycemic control was well-maintained.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical Trials as Topic↗