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PubMed1996

[Socioeconomic differences in the use and accessibility of health care services in Spain].

BACKGROUND: One of the main goals of the public health care systems is to assure an equitable accessibility and utilization of health care services according to the need for care. The present study evaluates the extent to which this objective has been reached in the Spanish National Health System from the socioeconomic perspective. POBLATION AND METHOD: The 1993 National Health Survey was used. Doctor consultation, use of inpatient hospital services, dentist consultation and gynaecologist consultation were the indicators of utilization analysed. Accessibility was measured by time spent travelling to the health centre, time spent waiting at health centre and time spent waiting for an ordinary admission to hospital. Educational level was the socioeconomic variable used. RESULTS: Doctor consultation and use of inpatient hospital services were more frequent in individuals with the lowest level of education, while dentist and gynaecologist consultation were in those with the highest level. No statistically significant differences were observed in doctor consultation and use of inpatient hospital services after adjusting for age, sex, health care coverage and several need indicators by using a multiple logistic regression model. On the contrary, the odds ratios for individuals with first, second and third educational level were 1.31 (CI 95% = 1.14-1.51), 1.74 (1.49-2.03) and 2.06 (1.71-2.47) in dentist consultation and 2.01 (1.71-2.35), 2.40 (2.01-2.87) and 2.54 (2.02-3.21) in gynaecologist consultation. On the other hand, individuals with no education showed the longest average waiting times, especially for an ordinary admission to hospital, which was 83.5 days for subjects with no education and 18.8 for those with third educational level. However, the multiple linear regression analysis only found statistically significant results in time spent travelling to the health center and time spent waiting at the health center. CONCLUSIONS: Although no differences in doctor consultation and use of inpatient hospital services by socioeconomic status were found, the results obtained regarding the use of other health care services and waiting times indicate the persistence of barriers limiting the equitable access and utilization of health care services in Spain.

Dental Health Services↗

PubMed1993

Development of a submaximal treadmill jogging test for fit college-aged individuals.

The purpose of this study was to develop a single-stage submaximal treadmill jogging test for the estimation of maximal oxygen uptake (VO2max). VO2max was measured in 129 relatively fit individuals (males = 84, females = 45), 18-29 yr, using a maximal treadmill protocol (mean +/- SD; VO2max = 48.3 +/- 6.2 ml.kg-1 x min-1, range = 35.6 to 62.3 ml.kg-1 x min-1). The treadmill test required subjects to sustain a comfortable, submaximal jogging pace (4.3-7.5 mph; level grade) until a steady-state heart rate was achieved (approximately 3 min). To help ensure that a submaximal level of exertion was realized for the treadmill jogging test, treadmill speed and exercise HR criteria were established that restricted treadmill speed to < or = 7.5 mph for males and < or = 6.5 mph for females and steady-state exercise HR < or = 180 bpm. Multiple regression analysis (N = 66) to estimate VO2max from the treadmill jogging test yielded the following validation (V) model (r(adj) = 0.84, SEE = 3.2 ml.kg-1 x min-1): VO2max = 54.07 + 7.062 * GENDER (0 = female; 1 = male) - 0.1938 * WEIGHT (kg) + 4.47* SPEED (miles.h-1) - 0.1453 * HEART RATE (bpm). Cross-validation (CV) of the treadmill jogging test comparing observed and estimated VO2max (N = 63) resulted in r(adj) = 0.88, SEE = 3.1 ml.kg-1 x min-1. The results indicate that this submaximal single-stage treadmill jogging test based on multiple linear regression provides a valid and convenient method for estimating VO2max.

Adolescent↗

PubMedDate not supplied

Enhanced blood conservation and improved clinical outcome after valve surgery using heparin-bonded cardiopulmonary bypass circuits.

BACKGROUND: Recently, heparin-bonded (HBC) cardiopulmonary bypass circuits (CPB) were formed to be associated with improved outcome after coronary artery bypass grafting. There are very few reports on the efficacy and safety of these circuits in valve surgery. METHODS: A retrospective cohort study of all patient populations undergoing first time valve surgery from 1992 to 1995 in a tertiary teaching hospital. Outcomes of 120 patients undergoing valve surgery using HBC and lower anticoagulation HBC were compared to 232 patients treated with conventional circuits and full heparinization (nonheparin-bonded-circuit [NHBC]). RESULTS: Postoperative 24-hour chest tube drainage (558 +/- 466 mL vs 1054 +/- 911 mL, p < 0.00001), and reoperation for bleeding (2.5% vs 8.2%, p = 0.04) were lower in the HBC group. HBC patients required significantly less transfusions (total donor exposure of 6.9 +/- 13.0 units vs 18.6 +/- 26.2 units, p < 0.00001). Multiple linear regression analysis identified CPB time as a predictor of increased homologous blood transfusions, and the use of HBC, a large body surface area, and elective procedure as predictors of decreased transfusions. Perioperative mortality was similar (HBC 2.5%, NHBC 4.7%, p = 0.24). Overall complications were lower in the HBC group (42% vs 56.2%, p = 0.02). Perioperative myocardial infarction (0.8% vs 1.3%, p = 0.58) and cerebrovascular accident (3.3% vs 3.9%, p = 0.53) were similar. Two (1.7%) HBC patients had valve re-replacement compared to none in the NHBC (p = 0.22). Multiple logistic regression model revealed that age and CPB time were associated with increased complications, and the use of HBC with reduced complications. CONCLUSION: Use of HBCs with lower anticoagulation in valve surgery resulted in a significant reduction of transfusion requirements and improved clinical outcome. Because of a potential for early mechanical valve thrombosis, until further data is available, conventional levels of systemic anticoagulation should be achieved when using HBC in valve surgery.

Aged↗

PubMed1993

Effect of antihypertensive therapy on the kidney in patients with diabetes: a meta-regression analysis.

OBJECTIVE: To assess the relative effect of different antihypertensive agents on proteinuria and renal function in patients with diabetes. DATA SOURCES: We used MEDLINE and bibliographies in recent articles to identify studies of the effects of antihypertensive agents on renal function in patients with diabetes. STUDY SELECTION: We selected 100 controlled and uncontrolled studies that provided data on renal function, proteinuria, or both, before and after treatment with an antihypertensive agent. DATA EXTRACTION: Data on blood pressure, renal function, proteinuria, patient characteristics (for example, age, sex, and type of diabetes), and study design (for example, random allocation and the use of a placebo) were extracted from selected studies. DATA SYNTHESIS: Multiple linear regression analysis indicated that angiotensin-converting enzyme (ACE) inhibitors decreased proteinuria independent of changes in blood pressure, treatment duration, and the type of diabetes or stage of nephropathy, as well as study design (P < 0.0001). Reductions in proteinuria from other antihypertensive agents could be entirely explained by changes in blood pressure. Blood pressure reduction in itself was associated with a relative increase in glomerular filtration rate (regression coefficient [+/- SE], 3.70 +/- .92 mL/min for each reduction of 10 mm Hg in mean arterial pressure; P = 0.0002); however, compared with other agents, ACE inhibitors had an additional favorable effect on glomerular filtration rate that was independent of blood pressure changes (3.41 +/- 1.71 mL/min; P = 0.05). CONCLUSION: Angiotensin-converting enzyme inhibitors can decrease proteinuria and preserve glomerular filtration rate in patients with diabetes. These effects occur independent of changes in systemic blood pressure.

Adolescent↗

PubMed1999

Circulating levels of interleukin-6, its soluble receptor and interleukin-6/interleukin-6 receptor complexes in patients with type 2 diabetes mellitus.

We evaluated the relationship between plasma fibrinogen concentration and the serum levels of interleukin-6 (IL-6), its soluble receptor, and their complex in patients with type 2 diabetes mellitus. The study comprised 57 patients with type 2 diabetes and 15 normal healthy controls. Serum levels of IL-6, soluble IL-6 receptor (IL-6R), and circulating IL-6/IL-6R complex were determined by enzyme-linked immunosorbent assays. Correlations between the different study parameters and serum IL-6, IL-6R, or IL-6/IL-6R complex levels were determined by multiple linear regression analysis. Any association between the different study parameters and the serum levels of IL-6, IL-6R, or IL-6/IL-6R complex were determined by stepwise linear regression analysis. The serum IL-6 level in diabetic subjects was significantly higher than in normal healthy controls (3.48 +/- 3.29 pg/ml vs 0.784 +/- 0.90 pg/ml, mean +/- SD, respectively, P = 0.0001). The specific optical density of the serum IL-6/IL-6R complex in diabetic patients was also significantly higher than in normal healthy controls, although there was no significant difference in the serum IL-6R level between diabetic patients and controls. The serum IL-6 concentration was correlated significantly with the HbA(1C) level (beta = 0.58, P = 0. 04) by multiple regression analysis. Stepwise regression analysis revealed that the levels of serum IL-6 (F = 8.251), HbA(1C) (F = 1. 08), and serum urea nitrogen (F = 5.603) were associated with the plasma fibrino gen concentration. These results suggest that hyperglycaemia and increased levels of serum IL-6 can increase the plasma fibrinogen concentration, one of the known risk factors for atherosclerosis in patients with type 2 diabetes mellitus.

Adult↗

PubMed2003

Neural network and multiple regression models for PM10 prediction in Athens: a comparative assessment.

Particulate atmospheric pollution in urban areas is considered to have significant impact on human health. Therefore, the ability to make accurate predictions of particulate ambient concentrations is important to improve public awareness and air quality management. This study examines the possibility of using neural network methods as tools for daily average particulate matter with aerodynamic diameter <10 microm (PM10) concentration forecasting, providing an alternative to statistical models widely used up to this day. Based on a data inventory, in a fixed central site in Athens, Greece, ranging over a two-year period, and using mainly meteorological variables as inputs, neural network models and multiple linear regression models were developed and evaluated. Comparison statistics used indicate that the neural network approach has an edge over regression models, expressed both in terms of prediction error (root mean square error values lower by 8.2-9.4%) and of episodic prediction ability (false alarm rate values lower by 7-13%). The results demonstrate that artificial neural networks (ANNs), if properly trained and formed, can provide adequate solutions to particulate pollution prognostic demands.

Air Pollutants↗

PubMed1969

Correlation between percentage of palmitic acid in adipose tissue and serum cholesterol level in patients with multiple sclerosis.

To investigate mechanisms controlling the concentration of serum cholesterol we studied its relationship to the proportions of fatty acids in the lipids of adipose tissue of patients with multiple sclerosis. In 26 men the serum cholesterol concentration had a significant multiple linear regression on the proportion of palmitic, palmitoleic, and grouped longer-chain acids in adipose tissues. In 29 women the serum cholesterol had a significant regression on the proportion of palmitic acid and age. Whether these observations would hold for normal people must be determined in future studies.

Adipose Tissue↗

PubMed2000

Longitudinal straightening effect of stents is an additional predictor for major adverse cardiac events. Austrian Wiktor Stent Study Group and European Paragon Stent Investigators.

OBJECTIVES: The aim of this study was to perform an investigation of the effects of the longitudinal straightening of coronary arteries by stents and the possible association with major adverse cardiac events (MACE) (primary end point) and angiographic restenosis (secondary end point). BACKGROUND: Stent deployment straightens a tortuous artery, and any consequent arterial longitudinal stretch may contribute to MACE and stent restenosis severity. METHODS: Clinical, qualitative and quantitative angiographic data on 404 patients with single stent implantation were subjected to multivariate nominal logistic regression analysis for the prediction of MACE. The predictive accuracy, sensitivity and specificity values and cut-off points of the continuous variables were determined via receiver operating characteristics curves. The longitudinal straightening effect of stents was characterized through the changes in vessel angle (defined by the tangents to the proximal and distal parts of the stenoses/stents). RESULTS: Follow-up angiography on 354 patients revealed 73 cases of stent restenosis (> or =50% diameter stenosis). Coronary bypass surgery was performed in 4 patients and repeated percutaneous transluminal coronary angioplasty in 56 patients; acute myocardial infarction (AMI) occurred in 2 patients, and 4 patients died during the follow-up. The overall incidence of MACE (death, AMI and revascularization) was 16.3% (66 patients). The best predictive accuracies and sensitivities/specificities of factors indicative of MACE were found for the minimal lumen diameter (MLD) at follow-up (predictive accuracy: 0.9305, sensitivity/specificity: 86.6%), the post-stent MLD (0.773, 77.2%), the percent diameter stenosis (%DS) at follow-up (0.9432, 87.1%), the prestent vessel angulation (0.6797, 68.2%) and the poststent changes in vessel angulation (0.6279, 62.2%). Multivariate nominal logistic regression analysis demonstrated that a poststent MLD < or =2.63 mm (p = 0.0017, odds ratio [OR] = 17.961, 95% confidence interval [CI] = 17.45-20.428), an MLD at follow-up < or =1.7 mm (p = 0.0059, OR = 11.880, 95% CI = 11.490-14.093), a %DS at follow-up > or =42.2% (p = 0.0000, OR = 49.553, 95% CI = 48.024-53.507), a prestent vessel angulation > or =33.5 degrees (p = 0.0477, OR = 5.404, 95% CI = 5.382-7.142) and poststent changes in vessel angulation > or =9.1 degrees (p = 0.0026, OR = 19.161, 95% CI = 18.562-21.750) were significant predictors for MACE. Multiple linear regression revealed that the poststent MLD (multivariate p = 0.0001), the MLD at follow-up (p = 0.0000), the prestent vessel angulation (p = 0.0431) and the changes in vessel angulation after stent implantation (p = 0.0316) were significant independent variables predicting angiographic stent restenosis severity. CONCLUSIONS: The longitudinal straightening effect of coronary artery stents contributes significantly to the occurrence of MACE and angiographic restenosis, and this finding may have an impact on future stent design.

Aged↗

PubMed2005

Exploring the relationship between hydrologic parameters and nutrient loads using digital elevation model and GIS - a case study from Sugarcreek headwaters, Ohio, U.S.A.

Ohio is typical among the Midwestern and Eastern United States with high levels of water pollutants, the main sources being from agriculture. In this study, we used a digital elevation model in conjunction with hydrological indices to determine the role of landscape complexity affecting the spatial and temporal variation in pollutant levels, in one of the most impaired headwater streams in Ohio. More than eighty five percent of the study area is dominated by agriculture. Spatial distribution of slope (S), altitude and wetness index along with other watershed parameters such as flow direction, flow accumulation, stream networks, flow stream orders and erosion index were used within a Geographic Information Systems framework to quantify variation in nitrate and phosphate loads to headwater streams. Stream monitoring data for nutrient loads were used to correlate the observed spatial and temporal patterns with hydrological parameters using multiple linear regressions. Results from the wetness index calculated from a digital elevation model suggested a range of 0.10-16.39, with more than 35% having values less than 4.0. A Revised Universal Soil Loss Equation (RUSLE) predicted soil loss in the range of 0.01-4.0 t/ha/yr. Nitrate nitrogen levels in the study area paralleled precipitation patterns over time, with higher nitrate levels corresponding to high precipitation. Atmospheric deposition through precipitation could explain approximately 35% of total nitrate levels observed in streams. Among the different topographic variables and hydrological indices, results from the step-wise multiple regression suggested the following best predictors, (1) elevation range and upstream flow length for nitrate, (2) flow direction and upstream flow length for ammonia-nitrogen and slope, and (3) elevation range for phosphate levels. Differences in the landscape models observed for nitrate, phosphate and ammonia-nitrogen in the surface waters were attributed partly to differences in the chemical activity and source strengths of the different forms of these nutrients through agricultural management practices. The results identify geomorphologic and landscape characteristics that influence pollutant levels in the study area.

Ammonia↗

PubMed1988

Subjective hunger relationships with meal patterns in the spontaneous feeding behavior of humans: evidence for a causal connection.

The relationship between the subjective state of hunger and objective food intake was investigated using a diary self-report method. Thirty-one adult humans were paid to record in a diary, for 7 consecutive days, everything that they either ate or drank, the time that they ingested it, and how hungry they were on a seven point scale. The diary entries were encoded and entered into a computer. Meals were identified according to 5 different definitions and meal compositions, estimated stomach contents, and intermeal intervals calculated. Univariate and multiple linear regression predictions of self-reported hunger and meal size were calculated from these data. Self-reported hunger was found to be related negatively to the energy content and the proportion of protein in the stomach at the time of meal ingestion. Meal size was also found to be related to these same factors and also positively to self-rated hunger. These results suggest that protein has a unique satiating property beyond its contribution to total food energy. When self-rated hunger and the premeal stomach contents were all used in a multiple regression prediction of meal size the premeal stomach contents influence became nonsignificant leaving subjective hunger as the only significant predictor of meal size. These results suggest that subjective hunger represents an intermediary step in the cause-effect sequence between gut filling and cessation of meal ingestion.

Adult↗

PubMed1997

[Pediatric ocular trauma: a retrospective survey].

PURPOSE: To determine the risk factors for pediatric ocular injuries, especially those resulting in severe visual impairment, and to identify the trends and preventable causes. METHODS: A retrospective survey was conducted for all pediatric trauma cases at Zhongshan Ophthalmic Center from January 1989 through December 1992. Four hundred eighty-seven cases of 15 years old or younger were recruited in this study. Stepwise regression analysis was used to identify the relations between the visual prognosis and the potential risk factors (age, gender, time after injury, type of injury, and cause of injury) RESULTS: The male to female ratio was approximately 3:1, and most were 4 to 8 years old. Non--perforating trauma in the anterior segment was the most common type of injury. The final recorded best corrected visual acuity was 0.3 or better in 65% of the patients, while 19% were found to be 0.05 or worse with best correction. The following formula was generated by multiple linear regression model: Visual outcome = 0.963775 - 0.0896543 x (type of injury). CONCLUSION: Pediatric ocular trauma may cause severe visual impairment and occurs most frequently at the age of 4 to 8 years. The visual outcome is mainly associated with the type of injury.

Adolescent↗

PubMed2000

Comparison of several approaches of therapeutic drug monitoring of cyclosporin A based on individual pharmacokinetics.

OBJECTIVE: The clinical outcome of patients after organ transplantation is correlated with cyclosporin A (CyA) exposure. It is generally accepted that the area under the concentration-time curve (AUC) provides a reliable means for drug exposure. However, in routine therapeutic drug monitoring (TDM) of CyA, trough levels are mostly used. Currently, a number of different new concepts of CyA-TDM, including approaches such as single, double or triple time-point and abbreviated AUC determinations, have been introduced. The purpose of this study was to compare the predictive value of the different strategies of TDM. METHODS: Calculations were based on 40 individual concentration time profiles after oral administration of CyA to patients who had been included into an ongoing prospective clinical trial. Non-compartmental analysis was used to calculate the AUC0-12h. Multiple linear regression was performed to describe the relationship between the different sets of blood concentrations and the respective AUC0-12h as well as to evaluate their predictive value regarding AUC. Predictive performance was assessed by prediction bias and prediction precision, which were estimated as the mean prediction error and root mean squared error, respectively. RESULTS: When comparing the various combinations of time points, it was found that one-point approaches showed the strongest differences with regard to the predictive value; the associated r2 values differed from 0.203 to 0.792. The two and three time-point approaches showed lower differences - r2 0.802-0.972. The four-point and five-point approaches (r2 0.942-0.982) were the strongest predictors for CyA AUC0-12h. Relative bias ranged from -27.7% to 63.8% and changed significantly when multiple-point predictors were used. In those cases, the predictive performance improved. Considering the predictive performance as well as the smallest bias and highest prediction precision, C3, C1 + C3, C1 + C3 + C6 and C1 + C2 + C3 + C6 were the best predictors. CONCLUSION: The results of this study indicate that in kidney transplant patients a clinically sufficient precise estimation of the CyA AUC is possible using two or three concentration time points.

Adult↗

PubMed1998

Response rate as an endpoint for evaluating new cytotoxic agents in phase II trials of non-small-cell lung cancer.

BACKGROUND: Response rate (RR) has been used as a defining endpoint of new-agent phase II trials for non-small-cell lung cancer (NSCLC). However, tumor responses to chemotherapy do not always result in prolonged survival of patients with this disease. DESIGN: Single-agent phase II trials were identified by a MEDLINE search of the period from 1976 to 1995. Associations between RR, median survival time (MST) and characteristics of patients who entered the trial, including tumor extent, performance status and prior chemotherapy, were studied by using the logistic regression model. RESULTS: A total of 183 treatment arms in 176 trials (including 10 randomized phase II trials) were identified. The overall RR in the 6768 evaluable patients was 11%. Eleven drugs, cisplatin, epirubicin, ifosfamide, edatrexate, irinotecan, vinorelbine, docetaxel, paclitaxel, etoposide, vindesine, and 254-S, produced a RR of more than 20%. An MST of eight months or longer was obtained with 12 drugs, but there were cases in which no objective responses were produced by these drugs. MST was correlated with RR (r = 0.504, P < 0.0001), but ranged broadly at a given level of RR. Multiple linear regression analysis showed a significant correlation between RR and MST (regression coefficient = 0.60, P = 0.00003) after adjustment for other variables. CONCLUSIONS: RR was significantly correlated with MST in single-agent phase II trials for NSCLC, but there is room for further consideration of the endpoint of these trials.

Antineoplastic Agents↗

PubMed1996

Relaxin secretion in in vitro fertilization pregnancies.

OBJECTIVE: This study was designed to determine whether the late luteal functional status of the corpora lutea in in vitro fertilization cycles alters the secretion of relaxin during pregnancy. STUDY DESIGN: Analysis of serum relaxin, human chorionic gonadotropin, and steroid concentrations in sera of women with pregnancies viable beyond the twelfth week as a result of in vitro fertilization treatment was performed. RESULTS: The serum estradiol and progesterone concentrations decreased 5.5- and 4-fold from days 5 to 6 after human chorionic gonadotropin to days 11 to 13 after human chorionic gonadotropin, respectively. The serum relaxin concentration increased 8-fold between the 11- to 15-day interval and the 16- to 50-day interval after human chorionic gonadotropin and another 6-fold to the 51- to 90-day interval after human chorionic gonadotropin (all p < 0.01). Multiple linear regression analysis showed that the serum estradiol level 11 to 13 days after human chorionic gonadotropin and the serum human chorionic gonadotropin level 11 to 15 days after human chorionic gonadotropin were the most powerful paired predictors of the concentration of serum relaxin measured in the 11- to 15-day interval after human chorionic gonadotropin interval (R2 = 0.39, n = 50), the 16- to 50-day interval (R2 = 0.61, n = 51), and the 51- to 90-day interval (R2 = 0.55, n = 39). CONCLUSION: Secretion of relaxin is determined by an interaction of the late luteal functional status of the corpora lutea and the human chorionic gonadotropin secreted by the implanting pregnancy. These data allow for the hypothesis that inducing functional luteolysis by substituting one or more injections of luteinizing hormone for the human chorionic gonadotropin injection may decrease secretion of steroids, relaxin, and other factors from the corpora lutea during pregnancy, decreasing the risk of premature delivery in multiple gestations and the ovarian hyperstimulation syndrome.

Chorionic Gonadotropin↗

PubMed2001

Acute adaptation of the vestibuloocular reflex: signal processing by floccular and ventral parafloccular Purkinje cells.

The gain of the vertical vestibuloocular reflex (VVOR), defined as eye velocity/head velocity was adapted in squirrel monkeys by employing visual-vestibular mismatch stimuli. VVOR gain, measured in the dark, could be trained to values between 0.4 and 1.5. Single-unit activity of vertical zone Purkinje cells was recorded from the flocculus and ventral paraflocculus in alert squirrel monkeys before and during the gain change training. Our goal was to evaluate the site(s) of learning of the gain change. To aid in the evaluation, a model of the vertical optokinetic reflex (VOKR) and VVOR was constructed consisting of floccular and nonfloccular systems divided into subsystems based on the known anatomy and input and output parameters. Three kinds of input to floccular Purkinje cells via mossy fibers were explicitly described, namely vestibular, visual (retinal slip), and efference copy of eye movement. The characteristics of each subsystem (gain and phase) were identified at different VOR gains by reconstructing single-unit activity of Purkinje cells during VOKR and VVOR with multiple linear regression models consisting of sensory input and motor output signals. Model adequacy was checked by evaluating the residual following the regressions and by predicting Purkinje cells' activity during visual-vestibular mismatch paradigms. As a result, parallel changes in identified characteristics with VVOR adaptation were found in the prefloccular/floccular subsystem that conveys vestibular signals and in the nonfloccular subsystem that conveys vestibular signals, while no change was found in other subsystems, namely prefloccular/floccular subsystems conveying efference copy or visual signals, nonfloccular subsystem conveying visual signals, and postfloccular subsystem transforming Purkinje cell activity to eye movements. The result suggests multiple sites for VVOR motor learning including both flocculus and nonflocculus pathways. The gain change in the nonfloccular vestibular subsystem was in the correct direction to cause VOR gain adaptation while the change in the prefloccular/floccular vestibular subsystem was incorrect (anti-compensatory). This apparent incorrect directional change might serve to prevent instability of the VOR caused by positive feedback via the efference copy pathway.

Action Potentials↗

PubMed1990

Between-lot variability in chromatographic and biochemical properties of hMG.

Ten lots of dissociated hMG were characterized by reverse-phase gradient high-performance liquid chromatography. Areas of 12 discrete peaks were directly related to dosages of hMG injected. The lots were further analysed for immunoactive-FSH (41.6-106.2 IU/ampule), immunoactive-LH (11.0-20.4 IU/ampule), bioactive-LH (2.7-17.1 IU/ampule) and bioactive-hMG (149-298 pg E2/mIU immunoactive-FSH/ml). Relationships between integrated areas of the HPLC peaks and biochemical properties of the hMG lots were analysed by stepwise multiple linear regression. Between-lot differences in immunoactive-LH and immunoactive-FSH were related to HPLC peak areas (p less than 0.05); differences in bioactive-LH were not. Areas of 8 peaks were related to differences in bioactive-hMG activity, facilitating close approximation of bioactive-hMG from the derived multi-linear model (p less than 0.001). Rapid characterization of hMG by HPLC is of relevance as recent reports have shown that ovarian responses and pregnancy outcomes of patients are related to the immunoactive and bioactive gonadotropin content of hMG preparations used to induce multiple folliculogenesis before oocyte aspiration, in vitro fertilization, and embryo replacement.

Animals↗

PubMed1998

Effects of long-term organophosphate exposures on neurological symptoms, vibration sense and tremor among South African farm workers.

OBJECTIVES: This study assessed the relationship between long-term exposure to organophosphate insecticides and neurological symptoms, vibration sense, and motor tremor after control for the effect of past poisoning and acute exposure. METHODS: This cross-sectional study included 164 pesticide applicators and 83 nonspraying reference workers on deciduous fruit farms. The workers were tested on the Vibratron II, on tests of dynamic and static tremor, and for a set of neurological and "dummy" symptoms. Exposure was derived with the use of a job-exposure matrix for pesticides in agriculture. RESULTS: Compared with nonapplicators, current applicators reported significantly more dizziness, sleepiness, and headache and had a higher overall neurological symptom score. This association remained statistically significant after multiple logistic regression analyses controlling for a range of confounders and effect modifiers [odds ratio (OR) 2.25, for current applicators having high neurological score, 95% confidence interval (95% CI) 1.15-4.39]. The average lifetime intensity of organophosphate exposure was nonsignificantly associated with both neurological (OR 1.98, 95% CI 0.49-7.94) and "dummy" symptoms (OR 2.37, 95% CI 0.54-10.35). Previous pesticide poisoning was significantly associated with the neurological scores (OR 4.08, 95% CI 1.48-11.22) but not with the "dummy" symptoms. Vibration sense outcomes were associated with age and height, but not with the organophosphate exposure measures. In the multiple linear regression modeling for tremor intensity in the dominant hand, recent organophosphate exposure in the past 10 days was a significant predictor (partial correlation coefficient = 0.04), but none of the long-term organophosphate exposure measures were significant. CONCLUSIONS: Strong evidence was found for an association between symptom outcomes and past organophosphate poisoning and between symptom outcomes and current spray activity. In contrast to symptoms, there was no association between either past poisoning or current spray activity and vibration sense or tremor outcome. Long-term organophosphate exposure did not appear to predict symptoms, vibration sense, or tremor outcome.

Adult↗

PubMed1998

Prediction of maximal aerobic power in healthy Indian males 21-58 years of age.

An attempt has been made in this paper to predict maximal aerobic power (VO2max) in healthy Indian males by three important physical characteristics (viz. age, height and body weight) using the technique of multivariate regression analysis for a wide age group ranging from 21 to 58 years. It has been observed that these characteristics can contribute significantly to the prediction of maximal aerobic power. Three combinations of predictors of two predictors at a time have also been tried to predict maximal aerobic power. Out of these three combinations, the combination of age and body weight has the maximum multiple correlation (R = 0.536, P < 0.001) for a group of 146 subjects of healthy Indian males. A nomogram has been constructed to predict VO2max from age and body weight in order to make the developed multiple linear regression equation of more practical utility to the biomedical scientists who may not be well acquainted with the statistical computational work.

Adult↗