Biomedical subjects

M Katz

Publications and source records attributed to M Katz.

At least 19 recordsLinked to original sources

PubMed2006

Risky behaviors among Ohio Appalachian adults.

This article describes the prevalence of risky behaviors known to be associated with increased cancer morbidity and mortality among Ohio Appalachian adults. These behaviors, or risk factors, include: 1) tobacco use; 2) energy imbalance (involving poor diet, obesity, and physical inactivity); and 3) sexual behaviors. We report current estimates of the prevalence of these behaviors among Ohio Appalachian adult residents and review social, psychological, and biological variables associated with these risky behaviors. We also present recent empirical studies that have been completed or are in progress in Ohio Appalachia. Finally, we discuss how these studies help bridge well-documented gaps in the literature.

Adult↗

PubMed2006

Leisure activities and the risk of amnestic mild cognitive impairment in the elderly.

OBJECTIVE: To study the influence of leisure activity participation on risk of development of amnestic mild cognitive impairment (aMCI). METHODS: The authors examined the relationship between baseline level of participation in leisure activities and risk of aMCI in a prospective cohort of 437 community-residing subjects older than 75 years, initially free of dementia or aMCI, using Cox analysis adjusted for age, sex, education, and chronic illnesses. The authors derived Cognitive and Physical Activity Scales based on frequency of participation in individual activities. RESULTS: Over a median follow-up of 5.6 years, 58 subjects had development of aMCI. A one-point increase on the Cognitive (hazard ratio [HR] 0.95, 95% CI 0.91 to 0.99) but not Physical Activities Scale (HR 0.97, 95% CI 0.93 to 1.01) was associated with lower risk of aMCI. Subjects with Cognitive Activity scores in the highest (HR 0.46, 95% CI 0.24 to 0.91) and middle thirds (HR 0.52, 95% CI 0.29 to 0.96) had a lower risk of aMCI compared with subjects in the lowest third. The association persisted even after excluding subjects who converted to dementia within 2 years of meeting criteria for aMCI. CONCLUSIONS: Cognitive activity participation is associated with lower risk of development of amnestic mild cognitive impairment, even after excluding individuals at early stages of dementia.

Aged↗

PubMed2006

Kernel least-squares models using updates of the pseudoinverse.

Sparse nonlinear classification and regression models in reproducing kernel Hilbert spaces (RKHSs) are considered. The use of Mercer kernels and the square loss function gives rise to an overdetermined linear least-squares problem in the corresponding RKHS. When we apply a greedy forward selection scheme, the least-squares problem may be solved by an order-recursive update of the pseudoinverse in each iteration step. The computational time is linear with respect to the number of the selected training samples.

Computer Simulation↗

PubMed2005

Dementia incidence may increase more slowly after age 90: results from the Bronx Aging Study.

BACKGROUND: Dementia incidence increases dramatically from age 65 to age 85, with many studies reporting a doubling every 5 years. The incidence beyond age 85 is not established. OBJECTIVE: To estimate the incidence of dementia as a function of age, with a particular focus on persons aged 85 and over. METHODS: The Bronx Aging Study began in 1980 with 488 healthy, nondemented community-dwelling individuals, age 75 to 85. Persons in the study received clinical examinations and cognitive testing approximately every 12 months until death or loss to follow-up. The diagnosis of dementia was made using Diagnostic and Statistical Manual of Mental Disorders-III-R at diagnostic case conferences. Dementia incidence rates were calculated for 5-year age bands using person-time of follow-up as the denominator. RESULTS: The relative incidence rate ratios of dementia for age 80 to 84 vs 75 to 79 was 2.32 (95% CI 1.23 to 4.37), the relative rate for age 85 to 89 vs 80 to 84 was 1.89 (95% CI 1.26 to 2.83), the relative rate for age 90 to 94 vs 85 to 89 was 1.49 (95% CI 0.86 to 2.58), while the relative rate for age 95 to 99 vs 90 to 94 was 1.31 (95% CI 0.38 to 4.46). Similar results were seen for men and women considered separately. Had the rate of increase from age 75 to 89 continued into the 90s, the study would have had 73% power to detect a significant difference between the rates for age 90 to 94 and 85 to 89 given the amount of observed follow-up time. CONCLUSIONS: Whereas dementia incidence continues to increase beyond age 85, the rate of increase appears to slow relative to that of 65- to 85-year-olds. These results suggest that dementia in the oldest old might be related not to the aging process itself but with age-associated risk factors.

Age Distribution↗

PubMed2005

Child health care centres: an academic model for comprehensive child health care in the community.

The challenge of the discipline of paediatrics in the 21st century is to promote health and development of children in a way that will enable them to maximize their biological and social potential. The community child health centre (CHC) in Israel is a model of community health care service built to provide comprehensive health care to children and adolescents, as well as an academic setting for under- and postgraduate paediatric training. Today there are 34 CHCs in Israel, serving a population of 220 000 children from birth to 18 years of age. The CHC combines the advantages of group practice with those of an academic medical centre and enables flexibility and mutual learning. Further expansion and development are required to realize the CHC's mission of a true comprehensive academic centre for paediatric community health.

Adolescent↗

PubMed2004

Vapor-transport equilibrated near-stoichiometric lithium tantalate for frequency-conversion applications.

Near-stoichiometric lithium tantalate (SLT) crystals were produced from congruent lithium tantalate by a vapor-transport equilibration process. Because of the resultant increase in photoconductivity and reduction in photogalvanism, the crystals showed no observable photorefractive damage at 514.5 nm up to the highest intensity used, 2 MW/cm2. The crystals also exhibited low green-induced infrared absorption, a Curie temperature of 693 degrees C, and a coercive field of 80 V/mm. The SLT samples were periodically poled with an 8-microm-period grating, permitting first-order quasi-phase-matched second-harmonic generation of 532-nm radiation at 43 degrees C. A 17-mm-long sample generated 1.6 W of continuous-wave output power at 532 nm for 50 h. With 150-ns pulses at a 100-kHz repetition rate in the same sample, 5-W average-power, 532-nm radiation was generated for 1000 h. No damage to the crystal and no aging effects were observed during these experiments.

Journal Article↗

PubMed2003

Social learning of food types in zebra finches (Taenopygia guttata) is directed by demonstrator sex and feeding activity.

In this study we examined how social learning of feeding preferences by zebra finches was affected by the identity of different demonstrators. We presented adult zebra finches with two demonstrators, one male and one female, that exhibited different food choices, and we recorded their subsequent preference when given a choice between the two food types. Previously it was found that young zebra finches' patterns of social learning are affected by the sex of the individual demonstrating a feeding behaviour. This result could be explained by the lack of exposure these animals had to the opposite sex, or by their mating status. Therefore, we investigated the social learning preferences of adult mated zebra finches. We found the same pattern of directed social learning of a different type of feeding behaviour (food colour): female zebra finches preferred the colour of food eaten by male demonstrators, whereas male zebra finches showed little evidence of any preference for the colour of food eaten by female demonstrators. Furthermore, we found that female observers' preferences were biased by demonstrators' relative feeding activity: the female demonstrator was only ever preferred if it ate less than its male counterpart.

Animals↗

PubMed2003

The reduction of a nitroxide spin label as a probe of human blood antioxidant properties.

The kinetics of reduction of the radical R*, 5-dimethylaminonaphthalene-1-sulfonyl-4-amino-2,2,6,6-tetramethyl-1-piperidine-oxyl by blood and its components were studied using the EPR technique. The results demonstrate that R* is adsorbed to the outer surface of the membrane and does not penetrate into the erythrocytes. A series of control experiments in PBS demonstrate that ascorbate is the only natural reducing agent that reacts with R*. The observed first order rate of disappearance of the nitroxide radical k, is: k(blood) > k(eryth) > k(plasma) and k(blood) approximately = k(eryth) + k(plasma). The results demonstrate that: a. The erythrocytes catalyze the reduction of R* by ascorbate. b. The rate of reduction of the radical is high though it does not penetrate the cells. c. In human erythrocytes there is an efficient electron transfer route through the cell membrane. d. The study points out that R* is a suitable spin label for measuring the reduction kinetics and antioxidant capacity in blood as expressed by reduction by ascorbate.

Antioxidants↗

PubMed2003

Placental abruption in term pregnancies: clinical significance and obstetric risk factors.

OBJECTIVE: To determine the incidence, obstetric risk factors and pregnancy outcome of placental abruption at term. METHODS: A comparison of all singleton term deliveries (> or = 37 weeks' gestation) complicated with placental abruption to singleton term deliveries without placental abruption. Multivariate analysis was performed to investigate independent risk factors for placental abruption. RESULTS: Placental abruption complicated 0.3% of all term deliveries (n = 72,995). A multiple logistic regression model with backward elimination found the following factors to be independently associated with the occurrence of placental abruption in term pregnancies: pregnancy-induced hypertension (PIH), intrauterine growth restriction (IUGR), non-vertex presentation, hydramnios and advanced maternal age. Perinatal mortality was significantly higher in pregnancies complicated with placental abruption (OR = 30.0, 95% CI 19.7-45.6; p < 0.001). In order to assess whether the increased risk for perinatal mortality was due to the placental abruption or to its significant association with other risk factors, a multivariate analysis was constructed with perinatal mortality as the outcome variable. Placental abruption (OR = 50.5, 95% CI 32.2-79.1), cord prolapse, small for gestational age and congenital malformations were found to be independent risk factors for perinatal mortality. CONCLUSION: Abruption of the placenta at term was found to be significantly associated with PIH, non-vertex presentation, IUGR, hydramnios and advanced maternal age. Owing to the independent association found between placental abruption and perinatal mortality, these conditions should be carefully evaluated in order to reduce the occurrence of placental abruption.

Abruptio Placentae↗

PubMed2002

An improved stereoselective reduction of a bicyclic diketone by Saccharomyces cerevisiae combining process optimization and strain engineering.

The stereoselective reduction of the bicyclic diketone bicyclo[2.2.2]octane-2,6-dione, to the ketoalcohol (1R,4S,6S)-6-hydroxybicyclo[2.2.2]octane-2-one, was used as a model reduction to optimize parameters involved in NADPH-dependent reductions in Saccharomyces cerevisiae with glucose as co-substrate. The co-substrate yield (ketoalcohol formed/glucose consumed) was affected by the initial concentration of bicyclic diketone, the ratio of yeast to glucose, the medium composition, and the pH. The reduction of 5 g l(-1) bicyclic diketone was completed in less than 20 h in complex medium (pH 5.5) under oxygen limitation with an initial concentration of 200 g l(-1) glucose and 5 g l(-1) yeast. The co-substrate yield was further enhanced by genetically engineered strains with reduced phosphoglucose isomerase activity and with the gene encoding alcohol dehydrogenase deleted. Co-substrate yields were increased 2.3-fold and 2.4-fold, respectively, in these strains.

Alcohol Dehydrogenase↗

PubMed2002

Tei-Index in coronary artery disease--validation in patients with overall cardiac and isolated diastolic dysfunction.

BACKGROUND: The index "isovolumic contraction time and isovolumic relaxation time divided by ejection time" ("Tei-Index") has been demonstrated to provide useful information about disease severity and prognosis in patients with dilated cardiomyopathy and cardiac amyloidosis. In patients with coronary artery disease (CAD), the diagnostic utility of this index is unclear. We attempted to validate the Tei-Index in CAD patients with overall cardiac or isolated diastolic dysfunction. METHODS AND RESULTS: Sixty subjects were included who underwent left heart catheterization for invasive measurement of left ventricular end-diastolic pressure (LVEDP): 20 symptomatic CAD patients with overall cardiac dysfunction (defined by a LV ejection fraction (EF) < 45% (mean 27 +/- 8%) and a LVEDP > or = 16 mmHg, (mean 22 +/- 6 mmHg), NYHA class 2.7 +/- 0.4, OCD group), 29 symptomatic CAD patients with isolated diastolic dysfunction (defined by an EF > 45% (mean 55 +/- 8%), a normal end-diastolic diameter index (mean 2.8 +/- 0.4 cm/m2) and a LVEDP > or = 16 mmHg (mean 22 +/- 6 mmHg), NYHA class 2.3 +/- 0.4, IDD group) and 11 asymptomatic control subjects (EF 65 +/- 9%, LVEDP 11 +/- 4 mmHg, CON group). After conventional 2-D- and Doppler echocardiographic examination, the Tei-Index was obtained. The Tei-Index was easily and reproducibly measured in all study subjects. In the OCD group, isovolumic contraction time was prolonged and ejection time was shortened in comparison to the CON group, resulting in a significantly increased Tei-Index (0.71 +/- 0.28 vs 0.40 +/- 0.11, p < 0.01). In the IDD group, isovolumic relaxation time was prolonged and isovolumic contraction time was shortened in comparison to controls, resulting in a largely unchanged Tei-Index (0.45 +/- 0.14, p = ns). Receiver operating characteristic curve analysis for the Tei-Index yielded an area under the curve of 0.92 +/- 0.04 for separating patients with vs without OCD. Using a Tei-Index > 0.49 as a cut-off, OCD patients were identified with a sensitivity of 96% and a specificity of 86%. CONCLUSION: The Tei-Index is a valid and readily derived indicator of global cardiac dysfunction in CAD patients with impaired systolic and diastolic LV performance. The use of this index seems to be limited in CAD patients with primary diastolic dysfunction.

Aged↗

PubMed2002

Nail involvement in pemphigus vulgaris.

BACKGROUND: Involvement of the nail unit in pemphigus vulgaris (PV) is thought to be rare. OBJECTIVES: To determine the frequency of nail changes among patients with PV. METHODS: Nail changes were recorded in patients with PV and were analysed retrospectively. Biopsies were taken from the nail bed and nail matrix for histological and immunofluorescence observations. Microscopic (potassium hydroxide) examination and fungal culture were performed. RESULTS: Nail changes were present in 30 of 64 (47%) patients with PV. Sixteen patients had onychomycosis and 14 had nail changes due to PV. These included onychomadesis, discoloration, deformity, onychorrhexis, onycholysis, subungual haemorrhage, subungual hyperkeratosis and paronychia. Onychomycosis affected fingernails and toenails, but changes due to PV occurred only in fingernails, most commonly on the thumb and index finger. No connection was found between the patient's occupation and nail involvement, and there was no correlation with the severity or duration of PV. In a control group of 64 patients of similar sex and age, only two had non-specific fingernail changes. CONCLUSIONS: Nail changes in PV may be more frequent than previously thought.

Adolescent↗

PubMed2002

Post-term pregnancy: should induction of labor be considered before 42 weeks?

OBJECTIVE: To determine the occurrence of maternal and fetal complications in low-risk pregnancies beyond 39 weeks and to re-evaluate the acceptable cut-off (42 weeks) for induction of labor. STUDY DESIGN: A total of 36 160 low-risk pregnancies with reliable dating of gestational age (last menstrual period and early ultrasound examination) were evaluated retrospectively for fetal and maternal complications, including non-progressive labor, cervical tear, retained placenta, postpartum hemorrhage, vacuum delivery, Cesarean section, macrosomia, meconium-stained amniotic fluid, non-reassuring fetal heart rate monitoring and ante-, intra- and postpartum death. Pregnancy outcomes at different gestational ages were compared using univariate and multivariate analysis and receiver operator curves. RESULTS: The rates of non-progressive labor stage I and II, retained placenta, vacuum delivery, Cesarean section, macrosomia, meconium-stained amniotic fluid and non-reassuring fetal heart rate monitoring were found to be significantly higher with increasing gestational age in the univariate analysis. These parameters were evaluated using multivariate analysis and the following were found to be significantly higher: non-progressive labor stage I and II, macrosomia, meconium-stained amniotic fluid and Cesarean section. Statistical analysis (receiver operator curves) showed that the most significant rise in the risk for non-progressive labor occurred after 42 completed weeks of gestation, and after 41 completed weeks for macrosomia, meconium-stained amniotic fluid and Cesarean section. CONCLUSIONS: The rates of non-progressive labor stage I and II, meconium-stained amniotic fluid, macrosomia and Cesarean section were significantly higher with increasing gestational age. In order to decrease the rate of macrosomia, meconium-stained amniotic fluid and Cesarean section, we suggest that induction of labor should be considered before 42 weeks.

Amniotic Fluid↗

PubMed2002

The effect of meconium on perinatal outcome: a prospective analysis.

OBJECTIVE: To evaluate the effect of meconium-stained amniotic fluid (AF) on perinatal outcome. METHODS: A prospective observational study was performed, comparing perinatal outcome of parturients with thick and thin meconium-stained AF to those with clear AF. RESULTS: The rate of meconium-stained AF was 18.1% (106/586). Of those, 78 (13.3%) patients had thin and 28 (4.8%) had thick meconium-stained AF. The rate of oligohydramnios was significantly higher among pregnancies complicated with thick meconium-stained AF (OR 7.2, 95% Cl 2.1-24.1; p = 0.002). A significant linear association, using the Mantel-Haenszel test for linearity, was found between the thickness of the meconium and abnormal fetal heart rate patterns during the first and second stages of labor, low Apgar scores at 1 min and the risk for Cesarean section. A statistically significantly higher risk for neonatal intensive care unit admission was observed among patients with thick meconium as compared to those with clear AF (OR 11.4, 95% CI 2.0-59.3; p = 0.006), even after adjustment for oligohydramnios and abnormal fetal heart rate patterns. CONCLUSIONS: Thick, and not thin, meconium-stained AF, was associated with an increased risk for perinatal complications during labor and delivery. Therefore, thick meconium-stained AF should be considered a marker for possible fetal compromise, and lead to careful evaluation of fetal well-being.

Adult↗

PubMed2002

Ripening of the uterine cervix in a post-cesarean parturient: prostaglandin E2 versus Foley catheter.

OBJECTIVE: To compare the success and complication rates of prostaglandin E2 tablets (PGE2) and a Foley catheter for the ripening of the uterine cervix in post-Cesarean section parturients. STUDY DESIGN: The study population in this retrospective cohort study consisted of parturients in their second pregnancy who had undergone Cesarean section in their previous delivery and who underwent ripening of the uterine cervix by using PGE2 (n = 55) or Foley catheter (n = 161) in the current pregnancy. The control group consisted of 1432 post-Cesarean section parturients without induction of labor. We compared the rates of placental abruption, non-reassuring fetal heart rate patterns, intrapartum fetal deaths (IPFD), uterine rupture, Apgar scores, labor dystocia, severe birth canal lacerations, vacuum deliveries and repeated Cesarean section rates in the three groups by using ANOVA, chi2 analysis and Fisher's exact test when appropriate. RESULTS: A significant increase in the rates of labor dystocia during the first stage (30.4% vs. 11.6%, p < 0.01) and repeated Cesarean deliveries (49.1% vs. 35.2%, p < 0.01) were observed in women in whom the Foley catheter was used as compared to controls, respectively. No such changes were demonstrated in the PGE2 group as compared to the controls. No significant differences were found between the PGE2 group and Foley catheter group as compared to the controls in rates of placental abruption, IPFD, uterine rupture, fetal distress, birth canal lacerations, vacuum deliveries and Apgar scores. CONCLUSIONS: PGE2 was found to be superior to the Foley catheter for ripening of the uterine cervix in a post-Cesarean parturient, as demonstrated by a lower repeated Cesarean delivery rate.

Adult↗

PubMed2002

A randomized comparison of psychological (cognitive behavior therapy), medical (fluoxetine) and combined treatment for women with premenstrual dysphoric disorder.

This study examines the relative effectiveness of cognitive behavior therapy (CBT) (ten sessions), fluoxetine (20 mg daily) and combined therapy (CBT plus fluoxetine) in women with premenstrual dysphoric disorder (PMDD). This was a randomized pragmatic treatment trial with three treatment cells. Treatment lasted for 6 months; a naturalistic follow-up was undertaken 1 year post-treatment. One hundred and eight women, satisfying the DSM-IV criteria for PMDD with 2 months' prospective confirmation were recruited into the study; sixty of these had completed 6 months of treatment and all measures before and after treatment. The main outcome measures were premenstrual scores on the Calendar of Premenstrual Experiences (COPE) and percentage of PMDD cases (DSM-IV diagnostic criteria). Significant improvement occurred in all three treatment-groups after 6 months' treatment, assessed by the COPE. Fluoxetine was associated with a more rapid improvement. There were no group differences in the percentage of DSM cases of PMDD post treatment, but at follow-up CBT was associated with better maintenance of treatment effects compared with fluoxetine. In conclusion, CBT and fluoxetine are equally effective treatments for PMDD, but the treatments have some differential effects that can be considered in treatment decisions. There appears to be no additional benefit of combining the treatments.

Adult↗

PubMed2001

Estimation of bivariate measurements having different change points, with application to cognitive ageing.

Longitudinal studies of ageing make repeated observations of multiple measurements on each subject. Change point models are often used to model longitudinal data. We demonstrate the use of Bayesian and profile likelihood methods to simultaneously estimate different change points in the longitudinal course of two different measurements of cognitive function in subjects in the Bronx Aging Study who developed Alzheimer's disease (AD). Analyses show that accelerated memory decline, as measured by Buschke Selective Reminding, begins between seven and eight years before diagnosis of AD, while decline in performance on speeded tasks as measured by WAIS Performance IQ begins slightly more than two years before diagnosis, significantly after the decline in memory.

Aged↗

PubMed2001

Gestational diabetes complicated by hydramnios was not associated with increased risk of perinatal morbidity and mortality.

OBJECTIVE: To determine whether gestational diabetes (GDM) complicated with hydramnios is associated with higher rates of perinatal morbidity and mortality than those with normal amniotic fluid (AFI). STUDY DESIGN: A case control study of 368 pregnant women with GDM was conducted between January 1995 and December 1996. The study group consisted of 184 women with hydramnios (AFI>25 cm) that were matched for maternal age, parity, and gestational age to 184 women with gestational diabetes and normal AFI. A Student's t-test, McNemar test and logistic regression test were used to compare the two groups. RESULTS: Both groups were under strict metabolic control; mean glucose levels of 5.2+/-2.4 mmol/l in the study group and 5.5+/-2.4 mmol/l in the controls (P>0.05). There were no significant differences between groups in the rates of severe preeclampsia, premature rupture of membranes (PROM), cesarean section rate, intrauterine growth restriction (IUGR), antepartum fetal death, fetal distress, prolapse of umbilical cord and placenta abruption. Even though the prevalence of large for gestational age (LGA) and birth weight were significantly higher in the study group (31 versus 19% and 3441+/-477 versus 3232+/-554 g, respectively), the prevalence of neonatal trauma was the same in both groups (2.6%). There was no significant difference in the Apgar scores (1 and 5 min), newborn hypoglycemia, metabolic acidosis and hyperbilirubinemia. CONCLUSIONS: Hydramnios in women with GDM was not associated with increased risk of perinatal morbidity and mortality.

Adult↗