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PubMed1996

The role of melatonin in the pathogenesis of adolescent idiopathic scoliosis.

STUDY DESIGN: A matched, case-control study comparing melatonin production in female patients with and without adolescent idiopathic scoliosis. OBJECTIVES: To determine whether melatonin production is decreased in adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: A central etiology for idiopathic scoliosis has never been established. Previous authors have produced experimental scoliosis in chickens after pinealectomy, preventable by administration of melatonin. They suggested that a defect in melatonin synthesis might be involved in the pathogenesis of human idiopathic scoliosis. METHODS: Nine female adolescents with no medical problems, normal neurologic examinations, radiographic idiopathic scoliosis of 15-40 degrees, and Risser Stage I-III were in the patient group. Eighteen healthy adolescent girls with no medical problems, a negative school screening, and no family history of scoliosis were control subjects. Patients and control subjects were matched for age, weight, Tanner stage, sleep duration, and light exposure by multiple linear regression. Nighttime and daytime urine samples were analyzed for melatonin by high-performance liquid chromatography. RESULTS: Although nighttime melatonin levels were significantly higher than daytime levels in all volunteers (P < 0.00002), there were no significant differences in nighttime (P > 0.63) or daytime (P > 0.78) melatonin levels between patients and control subjects, even after matching by multiple linear regression analysis. A statistical analysis demonstrated that if a melatonin deficiency of 25% or more did exist in patients with scoliosis compared with control subjects, the likelihood that it would have been detected in this study was more than 98%. CONCLUSION: Although melatonin deficiency may cause scoliosis in the chicken, this study suggests that it is not a mechanism in the pathogenesis of adolescent idiopathic scoliosis in humans.

Adolescent↗

PubMed2001

Reference data and predictive diagnostic models for calcaneus bone mineral density measured with single-energy X-ray absorptiometry in 7428 Chinese.

Calcaneus bone mineral density (BMD) of 7428 Chinese (4126 women, 3302 men; aged 22-94 years) was measured using single-energy X-ray absorptiometry (SXA). A reference range of calcaneus BMD values for healthy Chinese men and women was established and the usefulness of this method for screening and diagnosis in osteoporosis was evaluated. The peak BMD occurred at 20-24 years old and peak BMD in women was significantly lower than in men. BMD loss in the calcaneus started at the age of 35 years for women, and at 63 years in men. BMD loss rate was 1.2%/year for women and 0.56%/year for men after 50 years. The young normal reference for calcaneus BMD was 442.1+/-69.6 mg/cm2 for men and 388.3+/-61.7 mg/cm2 for women calculated from the mean BMD value of subjects whose age ranged from 20 to 49 years. The accumulated BMD loss in the calcaneus is similar to that of Ward's triangle. Multiple linear regression showed that both age and weight were important factors. The incidence of osteoporosis in older men and women (> or = 60 years) is 6.6% and 32.1% respectively. We conclude that calcaneus BMD measurement is useful and sensitive for the screening and diagnosis of osteoporosis. A predictive diagnostic model for osteoporosis based on the calcaneus was constructed using multiple linear regression and the WHO criteria for diagnosing osteoporosis can be applied to calcaneus BMD.

Absorptiometry, Photon↗

PubMed2000

The influence of menopause and body mass index on serum leptin concentrations.

OBJECTIVE: The aim of this study was to evaluate the influence of menopausal status, serum estradiol and body mass index (BMI) on serum leptin concentration in a large sample of pre- and postmenopausal women. DESIGN: 434 healthy women (mean age +/-s.d., 52.2 +/- 10.3 years) were recruited at the University of Marburg on the occasion of a routine gynecological visit. Two hundred and eighteen (50.2%) women were premenopausal (mean age, 36.5 +/- 10.4 years) and not on oral contraceptives or hormone replacement therapy (HRT) and 216 (49.8%) women were postmenopausal (mean age 61.8 +/- 8.9 years) not on HRT. To evaluate the influence of menopausal status, estradiol level and BMI on serum leptin concentrations, women were allocated to one of the four groups: (a) premenopausal women BMI <25 kg/m(2) (n=137), (b) premenopausal women BMI >25 kg/m(2) (n=81), (c) postmenopausal women BMI <25 kg/m(2) (n=94) and (d) postmenopausal women BMI >25 kg/m(2) (n=122). RESULTS: Irrespective of the menopausal status, women with a BMI >25 kg/m(2) had significantly higher leptin concentrations in all age groups compared with women with a BMI <25 kg/m(2) (P<0.001). The multiple linear regression analyses showed that BMI was the only statistically significant independent predictor for leptin. In comparison to postmenopausal women, premenopausal women showed a significantly lower mean age, weight, BMI and FSH concentration (P<0. 001), a higher mean height and serum estradiol (P<0.01 and P<0.001 respectively) but significantly lower serum leptin concentration (P<0.01). The multiple linear regression model showed no significant influence of menopausal status or serum estradiol on serum leptin concentration, even after controlling for BMI. CONCLUSIONS: Serum leptin concentrations are significantly higher in pre- and postmenopausal obese women, compared with normal weight controls. Serum leptin concentrations are not influenced by menopausal status or serum estradiol level.

Adult↗

PubMed2003

[Body mass index and triceps skinfold correlation in children from Paulínia city, São Paulo, SP].

UNLABELLED: Body mass index (BMI) has been considered a criterion to define and analyse obesity in adults and children. BACKGROUND: the purpose of this study was to evaluate the correlation between BMI and triceps skinfold (TSF). METHODS: there were studied 4,236 children (3.1-10.9y); 48.3%M:51.6%F, from four studies made in Paul nia, SP-Brazil. Height, weight and TSF (Holtain caliper) were measured. For each children BMI was calculated and transformed in SDS, according to North American data (Frisancho, 1993). Multiple linear regression analysis (stepwise) was used for the whole population and in three groups according to BMI: A) SDS < or = -1.0; B) -1.0 < SDS< 1.0) SDS(3) 1.0. Data were processed with SPSS software. RESULTS: in group A, the TSF (7.8 +/- 2.3) variability was lower when compared with the groups B (10.1 +/- 4.0) and C (17.8 +/- 6.2). In multiple linear regression with the whole population, R = 0.478 for TSF. In groups B and C, R = 0.364 and 0.368 respectively for TSF, and in group A it was only 0.032. CONCLUSIONS: these observations demonstrated a height correlation between BMI and TSF in children with obesity risk (group C). Therefore, we conclude that, in Brazil BMI can be used for children's research of obesity in population studies, instead of TSF.

Body Mass Index↗

PubMed2000

Direct impact of non-fatal occupational injuries.

OBJECTIVE: The objectives of this study were to describe the pattern of certain direct impacts of non-fatal injuries among workers insured by the General Organization of Social Insurance, admitted to hospitals in Al-Khobar City, and to determine factors influencing these direct impacts. METHODS: This cohort study consisted of 65, 915 insured male workers in various industries, followed to determine those who were admitted to 2 private hospitals selected randomly in Al-Khobar City. A data-collection sheet was used to collect the necessary data from patients and their medical records on admission to the hospital. RESULTS: The majority of admissions (78%) were for periods of less than a week. Absence from work was longer than 3 weeks in 35.5% and shorter than 1 week in 25% of admissions. The majority of the cases (65%) visited clinics from 2 to 7 times. Direct medical cost per admission was less than SR2,000 in 64% of the cases in one of the hospitals (one United States dollar = 3.75 Saudi Riyals). Multiple linear regression analysis for period of absence from work, length of hospitalization, and number of clinic visits showed these direct impact variables to be inter-related. Injury outside the work place (road traffic accidents), and the hospital which the injured worker was referred to, were the other main risk factors determining the direct impact of the injury. Multiple linear regression for direct medical cost was positively associated and predicted by the younger age of the worker. CONCLUSIONS: The direct impact of occupational injuries in this study, though less than the same reported from Western countries, were responsible for significant medical charges, human suffering and loss of productivity. Efforts made by different industries to prevent occupational injuries should be encouraged and continued, and the General Organization of Social Insurance may monitor their success by conducting similar studies.

Absenteeism↗

PubMedDate not supplied

A computerized method for measuring respiratory mechanics during mechanical ventilation.

In order to monitor respiratory mechanics in anesthetized ventilated subjects, an automated method was developed and tested on a physical model. The model was composed of an endotracheal tube (curvilinear resistance) coupled to a rigid air-filled box (elastance). Theoretical resistance was determined during steady-state flow experiments and theoretical elastance was estimated from the dimensions of the box. The physical model was connected to a volume-cycled ventilator. Pressure (P) and air flow (V) were measured at the outlet of the tube, and the time integral V of V was calculated. Elastance (E) and curvilinear resistance (R + K/V/) were identified by multiple linear regression analysis, for each ventilatory cycle, according to equation P = EV + RV + K/V/V. When linear regression analysis of P on V, V and /V/V was performed over the entire ventilatory cycle, E was found equal to its estimate, whereas R and K appeared different from their theoretical values. In order to improve determination of R and K, resistive pressure (Pr = P - EV) was calculated using the previously obtained value of E, and multiple linear regression of Pr on V and /V/V was performed over different fractions of the ventilatory cycle. When determined over the expiratory phase corresponding to decreasing flows, R and K were found close to their expected values. Such a method to calculate elastance and curvilinear resistance should prove convenient and efficient in measuring respiratory mechanics during mechanical ventilation.

Computers↗

PubMedDate not supplied

The use of midazolam for prehospital rapid-sequence intubation may be associated with a dose-related increase in hypotension.

OBJECTIVE: To investigate the incidence of hypotension associated with the use of midazolam for prehospital rapid-sequence intubation (RSI). METHODS: A retrospective review was performed using charts from the two aeromedical agencies servicing the authors' region. The RSI protocols used by crews from the northern (north) and the southern (south) parts of the region were identical, with the exception of midazolam dosing. The north crews used 0.1 mg/kg for all patients, while the south crews used 0.1 mg/kg up to a maximum of 5 mg. All patients receiving midazolam for prehospital RSI were pooled, with multiple linear regression used to investigate the relationship between midazolam dose and both hypotension and a decrease in systolic blood pressure (SBP) following RSI. Patients weighing >50 kg and patients with traumatic brain injury (TBI) were evaluated separately to determine differences between north and south with regard to midazolam dosing and incidence of hypotension. Multivariate logistical regression was used to test for these differences and for potential confounders such as age, initial SBP, and Glasgow Coma Scale score (GCS). RESULTS: A total of 219 patients were identified from the north (n = 75) and the south (n = 144). Multiple linear regression revealed a statistically significant relationship between midazolam dose and both hypotension and an SBP decrease following RSI. There was no difference between north and south with regard to age, sex, incidence of TBI, initial SBP, or GCS. In patients >50 kg, those from the north received higher doses of midazolam and had a higher incidence of hypotension than those from the south. This relationship was also present in 184 patients with TBI. CONCLUSION: The use of midazolam with prehospital RSI is associated with a dose-related incidence of hypotension.

Adult↗

PubMed1990

Amphotericin B revisited: reassessment of toxicity.

PURPOSE: Although amphotericin B remains the mainstay of therapy for serious fungal infections, numerous acute and chronic toxicities make clinical usage difficult. Nevertheless, utilization of amphotericin B has increased dramatically in recent years. Accordingly, a study to reassess toxicity associated with the use of amphotericin in the modern era and to determine the aggregate impact toxicities have on the overall therapeutic course of patients was undertaken. PATIENTS AND METHODS: The charts of 50 patients at our institution who had received amphotericin B were retrospectively reviewed for the occurrence of drug-related acute and chronic toxicities and their impact on therapy. Patients evaluated were at least 21 years of age, had received at least 100 mg of amphotericin B, and were treated for at least 3 days. An analysis to investigate associations between drug administration variables and toxicities was also undertaken. RESULTS: The mean age of study subjects were 54 years, the average duration of therapy was 19 days, and the mean cumulative dose of amphotericin B was 582 mg. Acute toxicities accompanying infusion occurred in 66% of all patients. Fever was experienced by 34% of study subjects and chills by 56%, with rates of 2.6 and 3.5 mean episodes per patient per treatment course, respectively. Other acute toxicities including hypotension were rare, and no patients exhibited bronchospasm or anaphylaxis. Nephrotoxicity occurred in 30 patients (60%). Baseline creatinine values in these patients rose by a mean of 1.55 mg/dL (137 mumol/L), with increases in creatinine ranging from 0.2 to 5.2 mg/dL (18 to 460 mumol/L). Analysis of six drug administration parameters by stepwise multiple linear regression failed to reveal any significant associations with nephrotoxicity. The mean nadir potassium value was 3.1 mEq/L (3.1 mmol/L) (range: 2.3 to 4.8 mEq/L [2.3 mmol/L]), with 45 of 50 patients (90%) receiving potassium supplementation (average daily supplement = 69 mEq). Only increasing amphotericin B concentration was correlated with an increased requirement for potassium supplementation (p less than 0.01, stepwise multiple linear regression). CONCLUSION: Although clinically important toxicities continue to occur with usage of amphotericin B despite current methods of infusion and premedication, these are usually manageable and rarely limit the course of therapy.

Adult↗

PubMed1998

Relationships between isoinertial lumbar dynamometry parameters and demographic parameters in chronic low back pain patients.

The purpose of this study was to investigate which demographic parameters are most important in relation to lumbar dynamometry performance in patients with chronic low back pain (LBP). Forty-five chronic LBP patients participated in this study. Gender, age, weight and height were determined and a lumbar dynamometry measurement was carried out, using the Isostation B200. Student's t-test, ANOVA techniques and correlation coefficients were used to investigate the relationships between each demographic parameter and lumbar dynamometry performance. Stepwise multiple linear regression analyses were performed afterwards to determine which demographic parameters are most important in relation to lumbar dynamometry performance. Results indicate significant relationships (1) between gender, height, weight and all lumbar dynamometry parameters and (2) between age and three of the six isometric torque parameters. No significant relationship was found between age and maximum velocity parameters. Results of the stepwise multiple linear regression analyses show that the demographic parameters explain 27-47% of the variance in maximum isometric strength parameters and 19-25% of the variance in maximum velocity parameters. Gender is the most important demographic parameter, being related to nearly all maximum isometric torque parameters (percentage explained variance 6-37%) and height is the only important demographic parameter related to the velocity parameters (percentage explained variance 19-25%). Weight and age account for only a small amount of variance in lumbar dynamometry parameters (percentage explained variance 5-7%), meaning that these parameters are non-relevant predictors.

Adult↗

PubMedDate not supplied

Dialysis adequacy and health related quality of life in hemodialysis patients.

Patients with end-stage renal disease have significant impairments in health related quality of life (HRQOL). The determinants of HRQOL, including the effect of dialysis adequacy, have not been well studied. This study was designed to investigate whether dialysis adequacy is associated with HRQOL in hemodialysis patients. A cross-sectional survey of 128 patients who had been on hemodialysis for more than 6 months was conducted. Baseline information on demographic factors and detailed clinical information was collected. Average Kt/V levels (for the 3 months preceding HRQOL assessment) were determined. HRQOL was assessed with the Kidney Disease Quality of Life Short Form, the Short Form-36 (SF-36), and the EuroQol EQ-5D. Multiple linear regression was performed to control for differences in important baseline covariates. Patients with average Kt/V levels greater than or equal to 1.3 had better HRQOL as measured by significantly higher scores (p < 0.05) in 4 of 11 kidney disease targeted domains, 6 of 8 SF-36 domains, and on the EQ-5D visual analog scale and index score. Using multiple linear regression to control for important covariates, the adjusted EQ-5D index score was higher by 0.036 (95% confidence intervals 0.015, 0.057) for each 0.1 increment in Kt/V, which is both statistically and clinically significant. Dialysis adequacy was significantly associated with HRQOL in hemodialysis patients. Controlled studies that examine the effect of increasing Kt/V on HRQOL are needed.

Aged↗

PubMed2000

Influence of metabolic state and diabetes on the outcome at the end of first year after gastric banding.

BACKGROUND: The influence of metabolic state and the presence of diabetes before surgery on the weight changes following non-adjustable gastric banding, were studied. METHODS: The total of 50 patients referred for gastric banding had the following parameters measured: insulinemia, glycemia, total cholesterol, triglycerides (TAG), dehydroepiandrostendione (DHEA) and its sulphate (DHEA-S), triiodothyronine, thyroxine, and thyroxine-stimulating hormone. We evaluated 28 of these, who completed at least 6 months of follow-up. 12 of these patients had diet-treated non-insulin dependent diabetes mellitus (NIDDM) and 16 were non-diabetics, and 9 of them had a positive family history of NIDDM (FH DM). We compared the change in weight of the diabetics, non-diabetics and those with positive FH DM, at 3, 6 and 12 months after the operation. Multiple linear regression tested the influence of the measured parameters on patients' weight. RESULTS: Weight loss was greatest in the group of patients without a positive family history of diabetes, and lowest in the diabetic group. Due to the high dispersion, differences in the t-test are not significant. When individual factors and their influence on weight development were tested by multiple linear regression, weight loss was greatest in patients with high TAG and low insulin levels and lowest in patients with diabetes or positive FH DM. CONCLUSIONS: Although post-operative weight can be influenced by other factors, eg. psychological ones, it is advisable to test each patient pre-operatively for insulin and TAG levels, and to establish family history of diabetes and presence of diabetes to give an idea of the prognosis of weight change.

Adult↗

PubMed1996

Specific and total carotenoid intakes among oral contraceptive and estrogen hormone users in the United States.

OBJECTIVE: To compare carotenoid intakes between hormone users and nonusers in a nationally representative sample of US women by demographic and lifestyle characteristics and to identify those with potentially greater risk for disease. DESIGN: Data from the 1987 National Health Interview Survey's-Epidemiology Supplement food frequency questionnaire were linked to the USDA-NCI Carotenoid database to estimate mean total and specific carotenoid intakes. SUBJECTS: Women (n = 8,962) were grouped by menopausal status and classified by hormone use into premenopausal oral contraceptive users/nonusers (n = 5,918) and postmenopausal estrogen replacement hormone users/nonusers (n = 3,044). STATISTICAL ANALYSES PERFORMED: Mean carotenoid intakes and standard errors were weighted using SUDAAN and adjusted for potential confounding factors using multiple linear regression analysis. Statistically significant differences were at p values < 0.01. RESULTS: Compared to nonusers, oral contraceptive users had lower specific carotenoid intakes. Demographic and lifestyle characteristics differed between oral contraceptive users/nonusers and were examined in relation to carotenoid intakes. More oral contraceptive users than nonusers were married, highly educated, drank alcoholic beverages, and smoked. After adjustment for these factors in a multiple linear regression model, the associations between oral contraceptive use and carotenoid intake remained statistically significant. Mean carotenoid intakes were not significantly different among estrogen hormone replacement users versus nonusers. CONCLUSIONS: Oral contraceptive users have lower dietary carotenoid intakes than nonusers. Since oral contraceptive users smoke and drink more than nonusers, and both factors are associated with lower carotenoid intakes, oral contraceptive users form a potential high risk group for disease.

Alcohol Drinking↗

PubMed2003

Procollagen II C propeptide level in the synovial fluid as a predictor of radiographic progression in early knee osteoarthritis.

OBJECTIVE: To investigate the prognostic value of procollagen type II carboxy-terminal propeptide (PIICP) level in synovial fluid in relation to early tibiofemoral joint osteoarthritis (OA). METHODS: Data were collected on 172 women (age 40 to 59 years) who had knee pain and tibiofemoral joint OA in the early stage. Standing semiflexed knee radiographs were obtained by fluoroscopy at baseline and at four year follow up and a computerised, magnification corrected measurement system was applied to measurement of minimal joint space width in the tibiofemoral compartment. Synovial fluid sampling was performed at baseline and at the four year follow up. Levels of PIICP in the synovial fluid were measured by enzyme immunoassay. The outcome measures were assessed by radiographic joint space narrowing (JSN) in the tibiofemoral joints over four years. Multiple linear regression analyses were used to examine the relation between radiographic JSN and synovial fluid level of PIICP. RESULTS: The number of women available at both baseline and at four year follow up was 110. The average of radiographic JSN over four years was 0.53 mm (range 0.00-2.01). Body mass index showed a slightly positive association with baseline PIICP level. In multiple linear regression analyses adjusted for age and body mass index, radiographic JSN over four years had a direct positive correlation with baseline PIICP level (r=0.395; 95% confidence interval (95% CI) 0.231 to 0.529; p<0.001). CONCLUSION: In a four year prospective study of women, quantification of synovial fluid PIICP was able to predict subsequent radiographic progression in early tibiofemoral joint OA.

Adult↗

PubMed1996

Changes in cerebral tissue perfusion during the first 48 hours of ischaemic stroke: relation to clinical outcome.

BACKGROUND: One major therapeutic strategy to minimise the extent of infarction after ischaemic stroke is to improve early reperfusion using thrombolytic agents. However, reperfusion may be hazardous and the period during which reperfusion may have a beneficial effect on tissue and clinical outcome is not known. METHODS: Fifty three patients were studied with serial cerebral perfusion (99mTcHMPAO SPECT) during the first 48 hours of ischaemic stroke to determine if changes in tissue perfusion during this time were prognostically significant. Single and multiple linear regression non-parametric analyses were used to include other factors during the same period which may influence outcome. RESULTS: In univariate analysis age, neurological score at admission, SPECT perfusion defect size in the first 24 hours, and percentage change in cerebral tissue perfusion at 24-48 hours (all P < 0.01) correlated significantly with the Barthel score at three months. In multiple linear regression analysis only age (P < 0.01) and percentage change in cerebral tissue perfusion at 24-48 hours (P < 0.01) provided independent prognostic information at three months. CONCLUSIONS: Changes in cerebral tissue perfusion during the first 48 hours of ischaemic stroke are significant outcome predictors and therapeutic effort aimed at increasing perfusion during this period seem to be justified.

Aged↗

PubMed1997

Relationship of cerebellar Purkinje cell simple spike discharge to movement kinematics in the monkey.

The simple spike discharge of 231 cerebellar Purkinje cells in ipsilateral lobules V and VI was recorded in three monkeys trained to perform a visually guided reaching task requiring movements of different directions and distances. The discharge of 179 cells was significantly modulated during movement to one or more targets. Mean simple spike rate was fitted to a cosine function for direction tuning, a simple linear function for distance modulation, and a multiple linear regression model that included terms for direction, distance, and target position. On the basis of the fit to the direction and distance models, there were more distance-related than direction-related Purkinje cells. The simple spike discharge of most direction-related cells modulated at only one target distance. The preferred directions for the simple spike tuning were not uniformly distributed across the workspace. The discharge of most distance-related cells modulated along only one movement direction. On the basis of the multiple linear regression model, simple spike discharge was also correlated with target position, in addition to direction and distance. Approximately half of the Purkinje cells had simple spike activity associated with only a single parameter, and only a small fraction of the cells with all three. The multiple regression model was extended to evaluate the correlations as a function of time. Considerable overlap occurred in the timing of the simple spike correlations with the parameters. The latency for correlation with movement direction occurred mainly in a 500-ms interval centered on movement onset. The correlations with target position also occurred around movement onset, in the range of -200-500 ms. Distance correlations were more variable, with onset latencies from -500 to 1,000 ms. These results demonstrate that the simple spike discharge of cerebellar Purkinje cells is correlated with movement direction, distance, and target position. Comparing these results to motor cortical discharge shows that the correlations with these parameters were weaker in Purkinje cell simple spike discharge, and that, for the majority of Purkinje cells, the simple spike discharge was significantly related to only a single movement parameter. Other differences between simple spike responses and those of motor cortical cells include the nonuniform distribution of preferred directions and the extensive overlap in the timing of the correlations. These differences suggest that Purkinje cells process, encode, and use kinematic information differently than motor cortical neurons.

Action Potentials↗

PubMed1998

Evaluation of platelet function by Sonoclot analysis compared with other hemostatic variables in cardiac surgery.

UNLABELLED: Platelet function can be easily measured as time to peak (TP) by Sonoclot Coagulation & Platelet Function Analyzer (Sienco Inc., Morrison, CO) analysis. However a correlation between Sonoclot analysis and platelet aggregation, which is accepted as a test of platelet function, has not been established. In this study, we compared TP and collagen-induced whole blood platelet aggregation in 15 patients undergoing cardiac surgery. Two or three blood samples were randomly obtained from each patient before and after cardiopulmonary bypass (CPB). Sonoclot analysis, collagen-induced whole blood aggregation, and laboratory measurement (including platelet count and coagulation profile) were measured. Seventy-two samples were obtained (35 before CPB and 37 after CPB). TP was correlated with collagen-induced whole blood aggregation (r = -0.652), platelet count (r = -0.671), fibrinogen level (r = -0.598), prothrombin time (r = 0.394), activated partial thromboplastin time (r = 0.486), and use of CPB (r = 0.380). Significant predictors of TP for multiple linear regression modeling were collagen-induced whole blood aggregation, platelet count, and fibrinogen level (r = 0.742). In conclusion, Sonoclot analysis TP predicts approximate platelet function in patients undergoing cardiac surgery. IMPLICATIONS: Approximate platelet function can be easily measured as time to peak by Sonoclot analysis. In this study, time to peak was predicted by platelet count, whole blood platelet aggregation, and fibrinogen level for multiple linear regression modeling.

Cardiac Surgical Procedures↗

PubMed1980

Epidemiology of infant mortality in Rio Grande do Sul, Brazil. The influence of agricultural production.

Infant mortality rates (IMRs) for the 24 districts of the State of Rio Grande do Sul, Brazil, for 1972, have been correlated to 12 variables representative of the state's agrarian structure, as well as five other socioeconomic variables, through Pearson's correlation coefficient and multiple linear regression. The IMR was found to be significantly larger in the districts characterized by large properties, cattle raising and wage earning, rather than in the districts of small properties, agriculture and large rural population. The IMR was not found to be correlated to the variables representing education, housing, medical care or availability of banks, but there was a direct association with the sanitation variable. A multiple linear regression equation was then obtained, in which the agrarian variables accounted for 70% of the variation in the IMR, while the non-agrarian ones accounted for 13%. These findings support the hypothesis that the agrarian structure of Rio Grande do Sul may influence the observed distribution of the IMR in the state, while other variables specifically related to the preservation and restoration of health do not seem to play an important role.

Agriculture↗

PubMed1996

The inhibition of alpha-chymotrypsin predicted using theoretically derived molecular properties.

The structures and molecular properties of 95 aromatic and heteroaromatic ligands previously tested as reversible inhibitors of chymotrypsin catalysis have been calculated using AMl. The properties obtained have been used as input for multiple linear regression analysis and as descriptors for a back-propagation neural network to predict the binding affinity of alpha-chymotrypsin inhibitors. Using polarizability, molecular shape, electrostatic similarity, dipole moment, ClogP, and the diagonalized quadrupole moments of the ligands, correlation coefficients between calculated and experimental affinities of 0.96 for the training set and 0.89 for the test set were obtained using a neural network. The performance of the multiple linear regression was significantly worse, although useful QSARs were also obtained.

Binding Sites↗