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PubMed1996

The care of older persons with diabetes mellitus: families and primary care physicians.

OBJECTIVES: To determine the extent to which family members participate in the day-to-day management of diabetes mellitus in older persons, and in older diabetics' medical encounters, and to identify patient and family member characteristics associated with this participation. DESIGN: A longitudinal observational study, with baseline data being reported herein. SETTING: Three primary care practice settings in Seattle, Washington, Boston, Massachusetts, and Indianapolis, Indiana. PARTICIPANTS: Family members of patients 70 years of age or older participating in the Patient Outcomes Research Team (PORT) Study of type II diabetics. MAIN OUTCOME MEASUREMENTS: The two dependent variables represent, respectively, the extent of family members' assistance with diabetes-related care and participation in older diabetics' medical encounters. RESULTS: The 357 family members enrolled were older (mean age = 66.3 years), were mostly women (76.2%), and were usually the spouses of diabetic patients (71.3%). Between 22% and 50% of family members reported helping with various aspects of diabetes care; 35.6% of family members participated regularly in their diabetic patients' medical encounters. A multiple linear regression model relating family assistance with diabetes-related care to patient and family member characteristics included four variables: patients' physical function, and the family member's relationship to the patient, assistance with basic activities of daily living (ADLs), and understanding of diabetes management issues (all P < .05). A multiple logistic regression model relating family member participation in the medical encounter to patient and family member characteristics also included four variables: patient age and physical function, and family member assistance with instrumental activities of daily living (IADLs) and with diabetes-related care (all P < .05). CONCLUSION: The family members studied frequently assisted older diabetics with diabetes-specific care; more than one-third were regular participants in older diabetics' medical encounters. Family member involvement in the day-to-day management of diabetes and in the medical encounter was more likely when patients were functionally disabled. Health care systems and physicians need to educate their older patients, and involved family members when patients are frail, about diabetes-related care issues and support them in their roles in the management of diabetes as well as other chronic diseases.

Activities of Daily Living↗

PubMed1998

Low plasma ascorbic acid independently predicts the presence of an unstable coronary syndrome.

OBJECTIVES: This study sought to investigate the relations between plasma antioxidant status, extent of atherosclerosis and activity of coronary artery disease. BACKGROUND: Previous studies indicate that increased antioxidant intake is associated with decreased coronary disease risk, but the underlying mechanisms remain controversial. METHODS: Plasma samples were obtained from 149 patients undergoing cardiac catheterization (65 with stable angina, 84 with unstable angina or a myocardial infarction within 2 weeks). Twelve plasma antioxidant/oxidant markers were measured and correlated with the extent of atherosclerosis and the presence of an unstable coronary syndrome. RESULTS: By multiple linear regression analysis, age (p < 0.001), diabetes mellitus (p < 0.001), male gender (p < 0.001) and hypercholesterolemia (p = 0.02) were independent predictors of the extent of atherosclerosis. No antioxidant/oxidant marker correlated with the extent of atherosclerosis. However, lower plasma ascorbic acid concentration predicted the presence of an unstable coronary syndrome by multiple logistic regression (odds ratio [OR] 0.59, 95% confidence interval [CI] 0.40 to 0.89, p = 0.01). The severity of atherosclerosis also predicted the presence of an unstable coronary syndrome (OR 1.7, 95% CI 1.14 to 2.47, p = 0.008) when all patients were considered. When only patients with significant coronary disease were considered (at least one stenosis >50%), ascorbic acid concentration (OR 0.56, 95% CI 0.37 to 0.85, p = 0.008) and total plasma thiols (OR 0.52, 95% CI 0.34 to 0.80, p = 0.004) predicted the presence of an unstable coronary syndrome, whereas the extent of atherosclerosis did not. CONCLUSIONS: These data are consistent with the hypothesis that the beneficial effects of antioxidants in coronary artery disease may result, in part, by an influence on lesion activity rather than a reduction in the overall extent of fixed disease.

Aged↗

PubMed2007

Quantification of diacylglycerol species from cellular extracts by electrospray ionization mass spectrometry using a linear regression algorithm.

Diacylglycerols (DAGs) play significant roles in both intermediate metabolism and signal transduction. These lipid species are second messengers involved in modulating a plethora of cellular processes. Evaluation of DAG species concentrations has been hampered by the lack of a reliable method for molecular species analysis within a complex mixture of cellular lipids. We describe a new method for quantitative analysis of DAG species from complex biological extracts based on positive mode electrospray ionization mass spectrometry without prior derivatization. Quantification is achieved using internal standards and calibration curves constructed by spiking cell extracts with different concentrations of DAG species containing various acyl chain lengths and degrees of unsaturation. The new mass spectral data processing algorithm incorporates a multiple linear regression model including a factor accountable for possible interactions between experimental preparations and the slope of the curve for the standards, allowing the examinations of the effects of sample origin conditions (such as cell types, phenotypes, etc.) and instrument variability on this slope. Internal standards provide a basis for quantification of 28 DAG molecular species detected in RAW 264.7 cells after stimulation of a G-protein coupled receptor with platelet activating factor. This method displays excellent reproducibility over the established range of concentrations with variations of < or =10% and is highly sensitive with a detection limit of 0.1-0.4 pmol/microL depending upon acyl chain composition. We have shown differential effects on various DAGs in response to a ligand which illustrates the importance of examining lipids at the molecular species level rather than as a single homogeneous entity.

Algorithms↗

PubMed2004

Accelerated progression of coronary calcification: four-year follow-up in patients with stable coronary artery disease.

PURPOSE: To prospectively assess the 4-year progression rate of coronary artery calcium (CAC) in patients with clinically stable coronary artery disease (CAD) with multi-detector row computed tomography (CT). MATERIALS AND METHODS: The study group consisted of 382 consecutive patients. All underwent baseline dual-sector spiral CT, and CT was repeated at 2 and 4 years later. Progression of CAC was assessed with measurement of the increase in total calcium score (TCS) and with repeated-measures analysis and multivariate linear regression models. Logistic regression model was used to predict incidence of new lesions. RESULTS: Eighty-seven percent (333 of 382) of the study group were men, with mean age of 65 years +/- 11, and 13% (49 of 382) were women, with mean age of 68 years +/- 11. The average TCS increased after 4 years by sixfold from baseline in the 1st quartile, and by four-, two- and 1.5-fold in the 2nd, 3rd, and 4th quartiles of baseline TCS (P <.01), respectively. Multiple linear regression analysis included age; sex; natural logarithm of baseline TCS; history of hypertension, diabetes mellitus, current smoking, hypercholesterolemia, and lipid-lowering therapy with cholesterol synthesis enzyme inhibitor (statin); and family history of premature CAD. Results demonstrated that natural logarithm of baseline TCS and history of current smoking were independent predictors of the 4th-year natural logarithm of TCS levels (R(2) = 0.85, P <.001). New lesions were diagnosed in 56 (15%) patients. History of statin therapy (odds ratio = 0.35; 95% confidence interval [CI]: 0.16, 0.77; P <.01), age with an increment of 5 years (odds ratio = 0.76; 95% CI: 0.64, 0.90; P =.01), and natural logarithm of baseline TCS (odds ratio = 0.73; 95% CI: 0.62, 0.86; P <.01) were independent predictors for new calcific lesions during 4 years. CONCLUSION: Accelerated progression of CAC during 4 years was found in clinically stable patients with CAD.

Aged↗

PubMed2005

Elevated plasma level of visfatin/pre-B cell colony-enhancing factor in patients with type 2 diabetes mellitus.

CONTEXT: Visfatin (also known as pre-B cell colony-enhancing factor or PBEF) is a cytokine that is highly expressed in visceral fat and whose blood levels correlate with obesity. Originally isolated as a secreted factor that promotes the growth of B cell precursors and recently found to act as an insulin analog on the insulin receptor, its pathophysiological role in humans remains largely unknown. OBJECTIVES: In this study we investigated whether plasma visfatin level is altered in patients with type 2 diabetes mellitus (T2DM). DESIGN AND PATIENTS: Plasma visfatin as well as adiponectin and resistin concentrations were measured through ELISA in type 2 diabetic and nondiabetic subjects. RESULTS: A total of 61 patients with T2DM and 59 sex- and age-matched nondiabetic subjects were studied. Plasma visfatin was found to be elevated in patients with T2DM (31.9 +/- 31.7 vs. 15.8 +/- 16.7 ng/ml, P = 0.002). In contrast, adiponectin was decreased (4.3 +/- 2.5 vs. 30.8 +/- 10.3 microg/ml, P < 0.001), whereas plasma resistin level did not differ between the groups. Increasing concentrations of visfatin were independently and significantly associated with T2DM. Multiple logistic regression analysis revealed visfatin as an independent association factor for T2DM, even after full adjustment of known biomarkers. The association between adiponectin and T2DM was no longer significant after adjustments for body mass index or waist to hip ratio. In a multiple linear regression analysis, only waist to hip ratio was independently associated with plasma visfatin level. CONCLUSION: Our results indicate that visfatin may play a role in the pathogenesis of T2DM.

Adiponectin↗

PubMed1997

The relationship of drinking and birth outcome in a US national sample of expectant mothers.

Alcohol consumption by pregnant women and birth outcome were studied in 9953 livebirths, 3309 fetal deaths and 5332 infant deaths from the 1988 National Maternal and Infant Health Survey. In crude analyses, race, age, mother's education, prenatal care, parity, low birthweight, gestational age, smoking and alcohol consumption during pregnancy were significantly related to the occurrence of fetal deaths and infant deaths. Among women having livebirths, race, age, mother's education, prenatal care, prematurity, gestational age, smoking and alcohol consumption during pregnancy were significantly related to having a low birthweight baby (< 2500 g). In this group, women who drank more during pregnancy also smoked more, were younger and less educated than women who drank at lower levels or not at all. The relationship of alcohol consumption during pregnancy and infant birthweight for those women having livebirths was studied using multivariable linear regression. The results indicated that race, mother's education, baby's sex, parity, mother's height, mother's body mass index and smoking, but not alcohol consumption, were significantly related to birthweight. Multivariable logistic regressions were performed for the occurrence of low birthweight, fetal death and infant death. The effect of alcohol was significant in all these analyses. These results indicate that alcohol has an important relationship with birth outcome, but that for the drinking reported in this study, the alcohol effect on mean birthweight is small relative to that of other risk factors, accounting for the non-significant result in the multiple linear regression.

Adult↗

PubMed2005

Cine MR imaging of myocardial contractile impairment in patients with hypertrophic cardiomyopathy attributable to Asp175Asn mutation in the alpha-tropomyosin gene.

PURPOSE: To prospectively investigate the relationship between myocardial contractile impairment and left ventricular (LV) hypertrophy measured at cardiac magnetic resonance (MR) imaging in patients with hypertrophic cardiomyopathy (HCM) caused by the substitution of aspartic acid 175 with asparagine (ie, Asp175Asn mutation) in the alpha-tropomyosin gene (TPM1). MATERIALS AND METHODS: The study protocol was approved by the hospital ethics committee, and all subjects gave written informed consent. LV mass, maximal LV wall thickness, and myocardial fractional thickening during systole were measured at cine MR imaging in 24 subjects (11 male, 13 female; mean age, 42 years; age range, 17-68 years) with the Asp175Asn mutation in TPM1 and in 17 healthy volunteers (eight men, nine women; mean age, 38 years; age range, 23-60 years). The proportion of hypokinetic LV segments was calculated as the number of LV segments with fractional thickening of less than 30% divided by the total number of segments measured. Anthropometric and biochemical correlates of LV hypertrophy were determined. Univariate and multiple linear regression analyses were used to investigate the association of the proportion of hypokinetic segments and other correlates of LV hypertrophy with LV mass and maximal wall thickness. RESULTS: The proportion of hypokinetic segments was higher in patients with HCM than in control subjects (37% +/- 20 [standard deviation] vs 12% +/- 12, P < .001). In stepwise multiple regression analysis, the proportion of hypokinetic segments accounted for 42% (P < .001); the LV end-diastolic volume, for 24% (P = .003); and male sex, for 10% (P = .014) of the variability in LV mass in patients with HCM. The proportion of hypokinetic LV segments, which accounted for 48% of the variability in LV maximal wall thickness (P < .001), was the only variable significantly associated with maximal wall thickness. CONCLUSION: The extent of myocardial contractile impairment is strongly and independently related to LV mass and maximal wall thickness in patients with HCM attributable to the Asp175Asn mutation in TPM1.

Adult↗

PubMed1993

Independent associations between plasma lipoprotein subfraction levels and the course of coronary artery disease in the St. Thomas' Atherosclerosis Regression Study (STARS).

Associations between plasma lipoprotein subfractions and changes in coronary artery diseases (CAD) were examined in 74 men who completed the St. Thomas' Atherosclerosis Regression Study (STARS). Plasma lipoproteins were isolated by stepwise, preparative ultracentrifugation at repeated intervals during the 38-month trial. Paired coronary angiograms were quantitatively analyzed by a computerized method. In univariate linear regression analysis, changes in mean absolute width (delta MAWS) and minimum absolute with (delta MinAWS) of coronary segments were significantly correlated with in-trial concentrations of cholesterol in intermediate-density lipoprotein ([IDL] d = 1.006 to 1.019 kg/L), low-density lipoprotein ([LDL2] d = 1.019 to 1.040 kg/L; LDL3, d = 1.040 to 1.063 kg/L), and high-density lipoprotein ([HDL3] d = 1.125 to 1.210 kg/L) subfractions; no significant associations were found with other lipoproteins. IDL, LDL3, and HDL3 cholesterol were then selected for multiple linear regression analysis because these variables were not co-correlated and because they attained a significance of P less than or equal to .1 in univariate regression. In this analysis, only LDL3 cholesterol level was a significant negative predictor (P < .05) of both delta MAWS and delta MinAWS; a positive association between delta MinAWS and HDL3 cholesterol level just failed to reach conventional statistical significance (P = .066). Correlations between changes in coronary luminal dimensions and LDL3 cholesterol level were independent of age, smoking, weight, and blood pressure. Most patients showing regression of coronary atherosclerosis had an LDL3 cholesterol level of less than 1.8 mmol/L. The findings suggest that LDL3 is the plasma lipoprotein subfraction that exerts the single most powerful effect on the course of CAD in middle-aged men with hypercholesterolemia.

Analysis of Variance↗

PubMed1997

Handgrip strength and insulin levels: cross-sectional and prospective associations in the Normative Aging Study.

Hyperinsulinemia is associated with insulin resistance and with the development of diabetes, hypertension, and coronary heart disease. Physical activity appears to be negatively associated with insulin resistance, although the mechanism is unclear. The relationship between physical activity and insulin resistance could be mediated, in part, by direct effects on skeletal muscle, a significant site for insulin-mediated glucose disposal. This report examines the relationship between skeletal muscle strength (as measured by handgrip dynamometry) and fasting insulin levels in a cohort of men in the ongoing Normative Aging Study (NAS). Handgrip strength was negatively associated (P = .013) with logarithmic (log) fasting insulin in cross-sectional data from 655 subjects after adjustment for potential confounders including age, body mass index (BMI), ratio of abdominal girth to hip breadth (AG/HB), usual physical activity level, and alcohol intake in a multiple regression model. In data collected prospectively among 1,195 subjects, handgrip strength measured at study entry was negatively predictive of log fasting insulin (P = .017) measured 22.9 +/- 2.6 years later, after adjustment for age, BMI, and AG/HB at study entry in a multiple linear regression model. A cross-sectional association was confirmed in an analysis of prospective data on the relationship between handgrip strength and fasting insulin levels. The findings suggest that skeletal muscle weakness may precede and predict the development of insulin resistance, and raise the intriguing possibility of some common cause in skeletal muscle pathophysiology.

Adult↗

PubMed2000

Inequalities in access to coronary angiography and revascularisation: the association of deprivation and location of primary care services.

BACKGROUND: Coronary artery surgery reduces re-infarction rates and mortality in patients with ischaemic heart disease. This study examines inequality in relation to primary care services. AIM: To determine the effect of primary care services on access to coronary angiography and revascularisation. METHOD: A cross-sectional survey of all 180 Nottinghamshire practices in the Trent region that were in existence between 1993 and 1997. The numbers of coronary bypass grafts, angioplasties, and angiographies were determined from the regional National Health Service database and linked to a database of general practice characteristics. Poisson regression analysis was used to determine the relationship between the angiography and revascularisation rates and the following practice characteristics: deprivation score, distance from nearest secondary or tertiary referral centre, medical cardiology admission rate for ischaemic heart disease, fundholding status, and partnership size. Multiple linear regression analysis was used to determine the relationship between practice characteristics and the waiting times for revascularisation and angiography. RESULTS: Practices with high deprivation scores had significantly lower rates of utilisation of angiography and revascularisation procedures. Their patients also waited longer for angiography. Practices that were 20 km or further from a revascularisation centre had significantly lower angiography and revascularisation rates. On average, their patients had to wait more than twice as long for an angiography compared with patients from nearer practices. Fundholding practices had higher angiography rates but similar revascularisation rates compared with non-fundholding practices. CONCLUSION: The results suggest that there may be some under-investigation and/or treatment of patients with ischaemic heart disease from 'deprived' practices and for those from practices far from a secondary or tertiary referral centre.

Cardiovascular Diseases↗

PubMed2005

Association between uric acid and carotid atherosclerosis in elderly persons.

OBJECTIVE: Several cohort studies have shown a link between serum uric acid (SUA) and subsequent cardiovascular disease. However, such an association did not remain significant after adjusting for concomitant risk factors for atherosclerosis in some studies. Thus, the role of SUA as an independent risk factor remains controversial. We therefore investigated the association between SUA and sclerotic lesions of common carotid atherosclerosis. PATIENTS AND METHODS: We evaluated sclerotic lesions of the common carotid arterial intima-media thickness (IMT) by ultrasonography in 398 men aged 74+/-8 (range, 60-97) years and 521 women aged 75+/-8 (range, 60-104) years. To investigate the relation between SUA and various factors, all subjects were divided into three groups based on the tertile of SUA. RESULTS: Stepwise multiple linear regression analysis using IMT as an objective variable, adjusted by various risk factors as explanatory variables showed that SUA [B, 0.0099; 95% confidence interval (CI), 0.0022-0.0175] was a significant independent contributing factor along with known risk factors such as age, sex, smoking status, systolic blood pressure, diastolic blood pressure, antihypertensive drug use, HDL-cholesterol, and LDL-cholesterol. Multiple logistic regression analysis for carotid IMT as a tertile of SUA and dependent variables showed that the adjusted odds ratio was 1.25 (95% CI, 0.87-1.78) for those in the middle tertile (4.2-5.5 mg/dl), and 1.66 (95% CI, 1.16-2.39) for those in the highest tertile (5.6-14.1 mg/dl) compared to that for subjects in the lowest tertile of SUA levels (0.51-4.1 mg/dl). CONCLUSION: We suggest that SUA is a risk factor or marker for ultrasonographically determined IMT.

Aged↗

PubMed1994

Correlates of left ventricular mass in a population sample aged 36 to 37 years. Focus on lifestyle and salt intake.

BACKGROUND: Echocardiographically determined left ventricular (LV) mass predicts adverse cardiovascular events in the general population. We have assessed the correlates of LV mass in a population-based study focusing on lifestyle and salt intake. METHODS AND RESULTS: A random sample of 120 persons born in 1954 was invited; 93 (42 men) entered the study. The subjects' physical activity and alcohol, tobacco, and coffee consumption were quantified by 2-month dairy follow-up, and sodium intake was quantified by 7-day food records. Blood pressure was averaged for casual cuff measurements made 2 months apart. LV mass was determined by M-mode echocardiography, and stroke volume was determined by Doppler. Hematocrit and serum insulin were measured. In multiple linear regression analysis, LV mass was related positively and independently (P < .05) to body weight, systolic blood pressure, stroke volume, sodium intake, hematocrit, and energy expenditure in leisure-time physical activity. Additional analyses showed that the relation of LV mass to daily sodium intake depended on blood pressure (P < .001 for the interaction); the multiple regression coefficient (+/- SE) was 0.41 +/- 0.11 g.mEq-1 x d-1 (P = .001) in subjects with systolic blood pressure above the population median but statistically nonsignificant (-0.15 +/- 0.10 g.mEq-1 x d-1) in those with lower blood pressure. LV mass was clearly elevated only in persons with both blood pressure and sodium intake above the population medians. CONCLUSIONS: Body weight, blood pressure, stroke volume, sodium intake, physical activity, and hematocrit are independent predictors of LV mass among unselected persons aged 36 to 37 years. The synergistic interaction of dietary salt with blood pressure suggests that high sodium intake may sensitize the heart to the hypertrophic stimulus of pressure load. Prospective studies are needed to confirm these cross-sectional associations.

Adult↗

PubMed2006

High monetary costs of dietary patterns associated with lower body mass index: a population-based study.

INTRODUCTION: Food choice is strongly influenced through economic constraints. The monetary costs for foods, especially those foods associated with a lower risk of obesity, have considerably increased during the last years. The purpose of this study was to determine the cost differences between low and high adherence to two dietary patterns which have been inversely associated with body mass index (BMI) and obesity. METHODS: The subjects were Spanish men (n=1547) and women (n=1615) aged 25-74 years who were examined in 1999-2000, in a population-based cross-sectional survey in the northeast of Spain (Girona). Dietary intake was assessed using a food frequency questionnaire. Two dietary quality indices, namely the Mediterranean Diet Score (MDS) and the Healthy Eating Index (HEI), were created. Average food prices were calculated. Anthropometric variables were measured. RESULTS: Adjusted linear regression analysis revealed that an increase in 1 Euro (1.25$) of monetary diet costs per day was associated with a change of 0.46 units (P<0.001) and 2.03 units (P<0.001) in the MDS and HEI, respectively. The magnitude of the association was similar for both scores after standardization. Subjects who closely adhered to the MDS and HEI paid daily 1.2 Euro (1.50$) (P<0.001) and 1.4 Euro (1.75$) (P<0.001) more for food consumption, respectively, than those who weakly adhered to these dietary patterns. Multiple linear regression analysis adjusted for several confounders showed an inverse association of the MDS (P=0.011) and the HEI (P<0.001) with BMI. The risk of obesity (BMI> or =30) significantly decreased across quartile distribution of MDS (P=0.004) and HEI (P=0.001). CONCLUSION: Data showed that a high adherence to the MDS and HEI, both inversely associated with BMI and obesity, led to higher monetary costs as compared to a low adherence. This might be of importance for public health policies in an effort to develop strategies to promote healthy diets preventing weight gain.

Adult↗

PubMed2006

Possible relationship between adiponectin and renal tubular injury in diabetic nephropathy.

Adiponectin is an adipose-derived protein which has anti-inflammatory and anti-atherogenic properties in addition to insulin-sensitizing effects. To date, the role of adiponectin in the pathogenesis of diabetic nephropathy remains unclear. The aim of the present study was to explore the relationship between adiponectin and renal tubular injury in diabetic nephropathy. We determined serum and urinary adiponectin levels in type 2 diabetic patients with normoalbuminuria (n = 19), microalbuminuria (n = 18), and overt diabetic nephropathy (n = 16), and then analyzed the correlations between serum and urinary adiponectin, urinary N-acetylglucosaminidase (NAG) as a clinical marker of renal tubular injury, urinary monocyte chemoattractant protein-1 (MCP-1) as an inflammatory marker in renal tubulointerstitium, and clinical markers of renal disease. Notably, serum and urinary adiponectin levels were significantly increased in patients with overt diabetic nephropathy compared to those with normoalbuminuria and microalbuminuria. In univariate linear regression analysis, serum adiponectin levels were positively correlated with serum creatinine (r = 0.648, P<0.0001), urinary albumin (r = 0.583, P<0.0001), urinary NAG (r = 0.406, P<0.01), urinary MCP-1 (r = 0.514, P<0.0001), and urinary adiponectin (r = 0.691, P<0.0001) levels in all diabetic patients. Urinary adiponectin levels were also positively correlated with serum creatinine (r = 0.729, P<0.0001), urinary albumin (r = 0.799, P<0.0001), urinary NAG (r = 0.701, P<0.0001), and urinary MCP-1 (r = 0.801, P<0.0001) levels in all diabetic patients. Multiple linear regression analysis showed that serum creatinine and urinary adiponectin levels were independently associated with serum adiponectin levels (r(2) = 0.522), and that serum creatinine, urinary NAG, urinary MCP-1, and serum adiponectin levels were independent determinants of urinary adiponectin levels (r(2) = 0.851). These results collectively indicate that renal insufficiency and tubular injury possibly play a contributory role in increases in serum and urinary adiponectin levels in overt diabetic nephropathy. We presume that an increase in circulating adiponectin in overt diabetic nephropathy might be a physiological response to mitigate renal tubular injury and to prevent the further progression of diabetic nephropathy through its anti-inflammatory and anti-atherogenic effects.

Acetylglucosaminidase↗

PubMed1990

A method for conforming the pH dependence of the michaelis parameters of nonallosteric enzymes to four kinetic schemes.

A nonlinear regression program for the analysis of the effect of pH on enzyme activity has been developed for the IBM micro range and compatible machines. The program conforms the V and Km pH profiles to one of four commonly occurring kinetic schemes. By using multiple linear regression the program computes initial estimates for the nonlinear search which are thus not required from the user. Two nonlinear optimization methods are included in order to effectively handle the nonnegativity constraints on the parameters. The program is user-friendly and provides plots of the fit and residual plots to help the user decide on the goodness of fit obtained. The program was coded in Turbo Pascal version 4.0 and runs on IBM micros or close compatibles with four types of graphics cards.

Algorithms↗

PubMed1996

Factors predicting successful labor induction.

OBJECTIVE: To evaluate maternal parity, the sonographic measurement of cervical length, and the five components of the Bishop score to determine which factors best predict the length of latent-phase labor in women undergoing labor induction. METHODS: Cervical position, cervical consistency, cervical effacement, cervical dilation, station of fetal presenting part, maternal parity, and sonographic measurement of cervical length were studied prospectively in 109 women undergoing labor induction. A multiple regression model was used to determine which factors best predict the length of latent-phase labor. RESULTS: A model using these seven factors was predictive in determining the number of hours of latent-phase labor (F = 32.1, P < .001). Backward stepwise multiple linear regression indicated that only cervical dilation independently predicted the length of latent-phase labor. There was a significant correlation between the clinical assessment of cervical effacement and the sonographic estimation of cervical length, (r = -0.523, P < .001). CONCLUSION: Only cervical dilation appears to predict the length of latent-phase labor. The sonographic evaluation of cervical length and maternal parity do not add significant independent information.

Cervix Uteri↗

PubMed2002

Phenolic antioxidants: electrochemical behavior and the mechanistic elements underlying their anodic oxidation reaction.

Electrochemical analysis has been widely used to assess activities of reductant antioxidants, but the mechanistic factors that determine reducing ability and their corresponding correlations remain to be explored further. In the present paper, the reactivity of a selection of phenolic compounds in anodic oxidation was investigated by cyclic voltammetry (CV). The effects of electron-donation ability, deprotonation equilibrium, stability of radicals and chemical hardness on reducing capacity were studied by computational chemistry methods and multiple linear regression analysis. The results suggested that all these factors made significant contributions to reducing potency although electron-donation ability of the parent molecule plays the most important role in the electrode reaction. With the majority of the compounds examined, the occurrence of multiple electrochemical reactions leading to irreversible anodic oxidation was implied by: (i) the characteristics of the radical cation intermediate; (ii) the propensity of the deprotonation reaction; and (iii) the reactivity of the parent molecule. Upon correlation analysis of oxidation potential and computed physicochemical descriptors, some new light was shed on the mechanism by which phenolic compounds act as antioxidant reductants in free radical reactions. A satisfactory multi-descriptor theoretical QSAR model was derived, which might be of predictive significance in the screening or design of new antioxidants.

Algorithms↗

PubMed1991

Serum human chorionic gonadotropin concentration for predicting multiple gestation in pregnancies conceived with superovulation and intrauterine insemination.

Assisted reproductive technologies are associated with an increased incidence of multiple gestation. Because they provide precise information on the time of ovulation, those technologies afford an opportunity to analyze the association between multiple gestation and maternal serum human chorionic gonadotropin (hCG) concentrations during early pregnancy. We retrospectively evaluated this association in 76 pregnancies (26 multiple) conceived with superovulation and intrauterine insemination. Using multiple linear regression, we discerned that the number of fetuses surviving the first trimester was directly proportional to the log of the hCG concentrations. The mean + 1 SD for the estimated hCG values of singleton pregnancies was selected a priori as the threshold for detecting multiple pregnancies. This threshold value provided a sensitivity of 73%, specificity of 80% and overall accuracy of 78%. Nine of 11 pregnancies with three or more fetuses had hCG concentrations above the threshold values. Although there is a positive correlation between the number of fetuses surviving the first trimester and the hCG concentration early in pregnancy, the predictive value of the hCG concentration is useful only for excluding most triplet and quadruplet pregnancies.

Chorionic Gonadotropin↗