Biomedical subjects

M Palta

Publications and source records attributed to M Palta.

At least 73 records · Page 4Linked to original sources

PubMed1993

The occurrence of sleep-disordered breathing among middle-aged adults.

BACKGROUND: Limited data have suggested that sleep-disordered breathing, a condition of repeated episodes of apnea and hypopnea during sleep, is prevalent among adults. Data from the Wisconsin Sleep Cohort Study, a longitudinal study of the natural history of cardiopulmonary disorders of sleep, were used to estimate the prevalence of undiagnosed sleep-disordered breathing among adults and address its importance to the public health. METHODS: A random sample of 602 employed men and women 30 to 60 years old were studied by overnight polysomnography to determine the frequency of episodes of apnea and hypopnea per hour of sleep (the apnea-hypopnea score). We measured the age- and sex-specific prevalence of sleep-disordered breathing in this group using three cutoff points for the apnea-hypopnea score (> or = 5, > or = 10, and > or = 15); we used logistic regression to investigate risk factors. RESULTS: The estimated prevalence of sleep-disordered breathing, defined as an apnea-hypopnea score of 5 or higher, was 9 percent for women and 24 percent for men. We estimated that 2 percent of women and 4 percent of men in the middle-aged work force meet the minimal diagnostic criteria for the sleep apnea syndrome (an apnea-hypopnea score of 5 or higher and daytime hypersomnolence). Male sex and obesity were strongly associated with the presence of sleep-disordered breathing. Habitual snorers, both men and women, tended to have a higher prevalence of apnea-hypopnea scores of 15 or higher. CONCLUSIONS: The prevalence of undiagnosed sleep-disordered breathing is high among men and is much higher than previously suspected among women. Undiagnosed sleep-disordered breathing is associated with daytime hypersomnolence.

Adult↗

PubMed1992

Glycemic control in early IDDM. The Wisconsin Diabetes Registry.

OBJECTIVE: A cohort (n = 277) was followed from diabetes diagnosis to evaluate longitudinal glycemic control, urinary C-peptide levels, and certain features of diabetes self-management. RESEARCH DESIGN AND METHODS: Unselected cases with IDDM, who were less than 30 yr of age, were identified at diagnosis from a 28-county area in Wisconsin. Subjects were asked to submit blood every 4 mo for GHb testing, to report aspects of diabetes self-management every 6 mo, and to collect a 24-h urine specimen 4 mo after diagnosis. RESULTS: In the 1st yr of diabetes, the rate of increase (0.23%/mo) in GHb was significant for the cohort (P less than 0.001) and for almost all age and sex subgroups. In the 2nd yr, there was no significant rate of increase for the cohort as a whole (P greater than 0.10). Adolescent males (10-19 yr of age) had a mean GHb level for year 2 higher than males of other age-groups and higher than female adolescents (P less than 0.001). Adolescent males had a significant rate of increase in GHb for year 2 (P = 0.02), unlike all other age and sex subgroups. Adolescents had higher initial 24-h urine C-peptide levels than children less than 10 yr of age (P less than 0.01). During the 2nd yr of diabetes, the percentage of adolescent males reporting three or more insulin injections/day was lower than any other subgroup. CONCLUSIONS: These data-suggest that glycemic control stabilizes during the 2nd yr of IDDM, except in adolescent males, and that this may be due partly to aspects of self-management.

Adolescent↗

PubMed1991

Multivariate assessment of traditional risk factors for chronic lung disease in very low birth weight neonates. The Newborn Lung Project.

All neonates (n = 581) with birth weights less than 1501 gm admitted to seven neonatal intensive care units in Wisconsin and Iowa were candidates for a study aimed at the multivariate assessment of risk factors for chronic lung disease while controlling for baseline severity of respiratory disease. Data from 361 neonates were analyzed for all risk factors except fluids; only neonates weighing less than 1200 gm were included (n = 220). Information on traditional risk factors for chronic lung disease was abstracted. A total of 110 (30%) of the analyzed neonates were oxygen dependent on day 30 of life. The following baseline factors were associated with increased risk of oxygen dependence in a joint multivariate model: lower birth weight (odds ratio 1.4/100 gm), higher baseline severity score (odds ratio 2.7/doubling at 32 weeks gestational age), lower gestational age (odds ratio 2.4/week at severity 0), Apgar score at 1 minute (odds ratio 1.6/2 points), male gender (odds ratio 1.9), and nonblack race (odds ratio 2.2). After adjustment for all baseline factors, patent ductus arteriosus, ventilator pressure at 96 hours, oxygen at 96 hours, and fluid intake were associated with oxygen dependence. Neonates with a low baseline severity score who remained oxygen dependent had a higher intake of fluid relative to output, whereas neonates with a higher baseline severity score had higher fluid intake and output. Lack of weight loss was associated with increased severity but not with oxygen dependence. The results of this study generally confirm the significance of previously reported risk factors for chronic lung disease in a multivariate setting but show that risk factors may not have the same impact in neonates with different baseline severity.

Chronic Disease↗

PubMed1991

Risk of diabetes in siblings and other relatives of IDDM subjects.

The risk of insulin-dependent diabetes mellitus (IDDM) was examined in siblings of an unselected population (n = 194) of newly diagnosed diabetic individuals less than 30 yr old. From 1 July 1984 to 30 June 1987, diabetic subjects (proband) identified within a geographically defined area of southern Wisconsin were studied. IDDM occurred among siblings of probands in 13.5% of families and was associated with proband age at diagnosis. The highest risk was found for diabetic subjects less than 10 yr old at diagnosis (P = 0.04). We did not find an association between sibling IDDM and proband sex, HLA-DR3/4, duration of symptoms, or ketosis at diagnosis. In addition, the odds ratio (OR) for the association of IDDM in the proband with IDDM in parents and second- and third-degree family members was examined by case-control methodology. Diabetic subjects were matched to two types of control subjects (friends and general population) by age stratum and sex. The OR for IDDM was not increased significantly if parental IDDM or non-insulin-dependent diabetes mellitus (NIDDM) was reported. However, there were very few parents with diabetes among diabetic or control subjects. In 6.4% of diabetic subjects, one parent had IDDM, 54% of whom were fathers. In 4.3% of diabetic subjects, one parent had NIDDM, and 57.1% of these were fathers. The OR for IDDM was significantly increased if second- and/or third-degree relatives had IDDM (OR diabetic subjects vs. general population 2.33 [P less than 0.05)] or NIDDM (OR diabetic subjects vs. friends 2.05 [P less than 0.01]).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1991

Analysis of longitudinal data with unmeasured confounders.

Confounding in longitudinal or clustered data creates special problems and opportunities because the relationship between the confounder and covariate of interest may differ across and within individuals or clusters. A well-known example of such confounding in longitudinal data is the presence of cohort and period effects in models of aging in epidemiologic research. We first formulate a data-generating model with confounding and derive the distribution of the response variable unconditional on the confounder. We then examine the properties of the regression coefficient for some analytic approaches when the confounder is omitted from the fitted model. The expected value of the regression coefficient differs in across- and within-individual regression. In the multivariate case, within- and between-individual information is combined and weighted according to the assumed covariance structure. We assume compound symmetry in the fitted covariance matrix and derive the variance, bias, and mean squared error of the slope estimate as a function of the fitted within-individual correlation. We find that even in this simplest multivariate case, the trade-off between bias and variance depends on a large number of parameters. It is generally preferable to fit correlations somewhat above the true correlation to minimize the effect of between-individual confounders or cohort effects. Period effects can lead to situations where it is advantageous to fit correlations that are below the true correlation. The results highlight the trade-offs inherent in the choice of method for analysis of longitudinal data, and show that an appropriate choice can be made only after determining whether within- or between-individual confounding is the major concern.

Analysis of Variance↗

PubMed1990

Development and validation of an index for scoring baseline respiratory disease in the very low birth weight neonate. Severity Index Development and Validation Panels and Newborn Lung Project.

An accurate description of the population at risk for neonatal chronic lung disease is clearly of prime importance for comparative studies and the planning of interventions. Attempts to explain variations in chronic lung disease rates in such studies have been compromised by lack of a way of estimating the severity of the initial pulmonary disease as a risk factor. Therefore, a severity index was developed for use in very low birth weight (less than 1501 g) neonates. Special emphasis was placed on applicability of the index in the multicenter observational setting. Development followed a clinician panel approach, with the resulting index designed to capture clinical judgment of severity. The index was validated prospectively on neonates in a neonatal intensive care unit, and retrospectively using charts from nine hospitals nationwide. Correlations of the index with clinical judgment in the two samples were .95 and .93, respectively. In an additional validation the index combined with birth weight correctly predicted oxygen dependence status at 30 days in 36 of 42 neonates consecutively admitted to five neonatal intensive care units (P = .002). Birth weight and the severity index contributed about equally to the prediction, and therefore they seem to represent partly independent components of baseline propensity for prolonged oxygen dependence.

Apgar Score↗

PubMed1989

The effect of saccharolactone on rat intestinal absorption of bilirubin in the presence of human breast milk.

Beta-glucuronidase hydrolyzes glucuronic acid from bilirubin glucuronides. The unconjugated bilirubin that results is more readily absorbed from the intestine. Human breast milk has significant beta-glucuronidase activity, and it has been suggested that the milk may play an etiologic role in the hyperbilirubinemia commonly seen in breast-fed infants. To test whether breast-milk can facilitate intestinal bilirubin absorption, pairs of rats were fitted with bile duct and duodenal catheters. One rat of each pair received an intraduodenal infusion of rat bile plus breast-milk; the other rat received a similar amount of bile and milk plus the beta-glucuronidase inhibitor saccharolactone. Rats receiving saccharolactone excreted significantly less bilirubin in their bile, suggesting that inhibition of beta-glucuronidase decreased intestinal absorption of bilirubin. These findings were not seen in similar experiments when saline was substituted for human breast-milk.

Animals↗

PubMed1988

Essential fatty acid deficiency in premature infants.

To better characterize essential fatty acid (EFA) deficiency in neonates, we assessed 63 premature infants by serial determinations of plasma fatty acids for the level of linoleic acid, the presence of an abnormal trienoic acid (5,8,11-eicosatrienoic acid [20:3 omega 9]), and the ratio of this compound to arachidonic acid, ie, the triene-tetraene ratio. The data indicated that at age 7 d, 67% of these infants had low plasma linoleic acid levels, 62% showed readily detectable 20:3 omega 9, and 44% had a high triene-tetraene ratio. Infants fed by age 2 d had a normal mean linoleate level at 7 d and none showed detectable 20:3 omega 9 by 10 d. In contrast, infants who were not fed until 7 d showed a very high incidence of abnormal fatty acid status. By maintaining a daily record of linoleate intake, we calculated from regression models that the average amount required to achieve normal fatty acid nutrition was 1.19 g.kg-1.d-1.

8,11,14-Eicosatrienoic Acid↗

PubMed1987

Temporal aspects of the electroretinogram in diabetic retinopathy.

We measured the temporal aspects of several components of the electroretinogram in 72 patients with diabetes and 29 control subjects. The measurements consisted of the implicit times of the a wave and oscillatory potentials elicited by a bright-flash stimulus and the implicit time of the b wave in response to a 30-Hz flickering light. The a wave and first three oscillatory potential nodes were significantly delayed in the patients with diabetes compared with the controls; among the diabetics, a significant increase in the delay of the second and third nodes occurred as a function of increasing retinopathy severity. Similarly, the 30-Hz flicker implicit times (with and without a background light) were significantly delayed in patients with diabetes, and the magnitude of the delay increased with increasing retinopathy severity. The correlations of 30-Hz flicker implicit times with retinopathy severity were significant for retinopathy level graded in color fundus photographs as well as for retinal capillary nonperfusion and leakage graded in fluorescein angiograms. A comparison of 30-Hz flicker implicit times in 15 patients with one eye treated with panretinal laser photocoagulation and the other eye untreated (treatment was randomly assigned) showed a significant delay in the treated eyes compared with the untreated eyes (paired eye comparison). This suggests that panretinal laser photocoagulation induces a further delay in the b-wave implicit times of eyes treated for diabetic retinopathy.

Adult↗

PubMed1987

Predicting progression to severe proliferative diabetic retinopathy.

The longer-term progression of retinopathy was observed in a previously described group of 85 diabetic patients enrolled in the Early Treatment Diabetic Retinopathy Study. The probability of progression to severe retinopathy was significantly greater for eyes with the following baseline characteristics: greater overall retinopathy severity, higher fluorescein leakage, higher capillary nonperfusion, and lower electroretinographic oscillatory potential amplitudes. The summed amplitudes of the oscillatory potentials, the overall severity of retinopathy, and the severity of fluorescein angiographic leakage were found to be independent predictors of progression to severe proliferative retinopathy in a regression model; capillary nonperfusion was not found to predict progression independently when fluorescein leakage was included in the model. Probability curves based on the regression model can be used to support clinical decisions concerning when to perform panretinal laser photocoagulation and how often to follow up patients with less than severe proliferative diabetic retinopathy.

Adult↗

PubMed1987

Oscillatory potential amplitudes. Relation to severity of diabetic retinopathy.

The oscillatory potentials of the electroretinogram and other visual function tests were evaluated in a group of 174 diabetic and 54 control subjects. Retinopathy severity in diabetic patients was measured in color fundus photographs and fluorescein angiograms. The summed amplitudes of the oscillatory potentials were significantly lower in diabetic compared with control subjects, and the amplitudes decreased progressively as the retinopathy severity increased. Among diabetic patients, a significant correlation was found between the oscillatory potentials and the other visual function tests; lower amplitudes were associated with lower visual field and visual acuity scores and higher Farnsworth-Munsell 100-hue error scores. Stepwise regression analysis showed that the most important predictors of oscillatory potential amplitudes were retinopathy level, fluorescein leakage, and age; capillary nonperfusion did not add to the predictive power of the model when fluorescein leakage was included.

Adult↗

PubMed1987

Predigested formula for infants with cystic fibrosis.

The object of this study was to assess the growth rates of patients with cystic fibrosis fed various diets and test the hypothesis that the weight of infants could be normalized by 1 year of age if they were placed on predigested formula before age 6 months. A group of 19 newly diagnosed patients placed on Pregestimil were compared with a group who were fed standard formula. At 1 year of age, the Pregestimil group showed significantly greater length and weight and a twofold higher average weight percentile. Growth velocity determined for the period between diagnosis and 12 months of age was better (p less than .001) for babies raised on Pregestimil (556 compared with 423 gm/month). Using weight percentile as the major growth index and values less than the fifth percentile as abnormal at age 12 months, we found that all 19 babies were normal in the group fed Pregestimil, whereas nine were below the fifth percentile in the group fed regular formula (p = .0006).

Birth Weight↗

PubMed1986

Incidence and differences in urban-rural seasonal variation of type 1 (insulin-dependent) diabetes in Wisconsin.

In a hospital-based records study of Type 1 (insulin-dependent) diabetes mellitus among persons aged 0 to 29 years in two Wisconsin, USA counties (1970-79), the age-adjusted yearly incidence rate for white males (16.4/100,000) was significantly higher than for white females (11.6/100,000) (p = 0.006). Overall age-adjusted rates are similar to rates previously reported for the United States and the northern European countries of Denmark and Norway. Seasonal variation in diagnosis was found for total cases and males aged 10 to 19 years. A striking difference also was found in seasonal diagnosis between urban and rural cases. A diagnosis peak in the third and fourth quarter among rural cases contrasted with even quarterly distribution among urban cases. In addition, 52% of rural male cases aged 10 to 19 years were diagnosed during the fourth quarter while no seasonal pattern occurred among urban males the same ages. These findings identify subgroups for focus of future etiologic investigations.

Adolescent↗

PubMed1986

Fetal lung development in male and female nonhuman primates.

Indices of lung maturation were assessed in 58 rhesus fetuses at five gestational ages during the last trimester of nonhuman primate pregnancy to determine whether fetal sex influences lung maturation. In addition to analysis of whole lung phospholipids, glycogen, protein, DNA, and pressure-volume curves surfactant fraction phosphatidylcholine (PC) was quantitated following isolation by sucrose gradient centrifugation and a combination of predictors were assessed by all possible subsets regression to attain a composite "maturity index." For the total population, there was a uniform progression in physical growth characteristics, lung destensibility and stability and phospholipids with advancing gestation. The quantitative change in surfactant fraction PC concentration for both sexes was considerably greater than that observed for whole lung PC between 135 days gestation and term. Further, the increase in surfactant PC occurred in association with improving lung destensibility and deflation stability prior to maximum changes in the whole lung PC or disaturated PC concentration. There were no statistically discernible differences in biochemical or physiological assessment between sexes at any gestational age. These data in nonhuman primates suggest that documented differences in survival from the respiratory distress syndrome between males and females do not result from a discordance in lung maturation as a function of time throughout the last trimester of gestation.

Animals↗

PubMed1986

Discordance between male and female deaths due to the respiratory distress syndrome.

General neonatal mortality statistics and those for the respiratory distress syndrome (RDS) were examined for the State of Wisconsin from 1979 through 1982. The objectives were to ascertain whether there are differences in total neonatal mortality related to sex and birth weight, to determine the veracity of reported gender differences in deaths due to RDS, and to assess the contribution of other risk factors for neonatal mortality to overall and sex-specific deaths occurring secondary to RDS. Additionally, a prospective analysis was performed at one perinatal center during a 5-year period in attempts to determine whether gender remained a significant factor in deaths due to RDS after adjusting for incidence. Overall, the most frequent diagnoses in those who died were RDS (15.6%), deaths due to complications of pregnancy (8%), immaturity (4.2%), and asphyxia (3.4%). The majority of fatalities for both sexes occur in neonates weighing less than 1 kg and the percentage of deaths attributable to RDS is greatest between 1 and 1.5 kg. The difference between sexes is also maximal in the latter weight group. Deaths secondary to RDS are greater for males regardless of Apgar score at one and five minutes, mode of delivery, maternal age, or ancillary diagnosis. These data suggest that deaths secondary to RDS are consistently greater in male neonates and that delivery within a limited "window" of time during gestation increases male susceptibility to fatal RDS.

Apgar Score↗

PubMed1985

Association of hue discrimination loss and diabetic retinopathy.

The results of Farnsworth-Munsell 100-hue, visual acuity, and visual field testing were compared with the severity of retinopathy in a group of 90 diabetic patients. The patients showed significantly higher than expected Farnsworth-Munsell 100-hue scores, with a tritanlike axis, compared with published age norms for nondiabetic individuals. The magnitude of the acquired blue-yellow hue discrimination defect correlated significantly and to a similar extent with both the severity of overall diabetic retinopathy and the severity of macular edema and hard exudate formation. Visual acuity loss correlated somewhat more significantly with macular edema than with overall retinopathy, whereas the converse was true for visual fields. For all visual function tests, the correlations were more significant for fluorescein leakage in the macula than for capillary nonperfusion in the macula. Abnormal hue discrimination was found in 65% (32/49) of eyes with proliferative diabetic retinopathy, suggesting a potential role for this test in screening for proliferative diabetic retinopathy in primary care facilities. Also, because the ability of diabetic patients with color vision deficiency to perform color-dependent tests for urinary and blood glucose may be impaired, such patients should be made aware of this potential problem.

Adult↗

PubMed1985

Short term high density systemic therapy for metastatic breast cancer.

Twenty-three patients with metastatic breast carcinoma were induced with a complex systemic therapy regimen in an attempt to ascertain if a complete remission rate greater than 50% could be obtained with intensive drug exposure. The durability of the remissions was observed by discontinuing therapy after 3 cycles in complete remission or after 6 cycles of treatment, whichever was longer. In 13 patients consolidation radiation therapy to the pre-treatment sites of disease was administered after discontinuing systemic therapy. Each 28 day cycle of the drug regimen consisted of pulses of adriamycin, vincristine, dibromodulcitol, prednisone, methotrexate with leukovorin rescue, hexamethylmelamine, bleomycin (discontinued after entry #17), fluoxymesterone, and tamoxifen. Eighteen of the 23 patients achieved complete remissions (78%) and 3 had partial remissions. The median times to treatment failure and survival were, respectively, 12.3 and 19.4 mos. The times for complete remission patients were, respectively, 13.5 and 23.9 mos. Consolidation radiotherapy at greater than or equal to 40 Gy to drug induced pre-study sites of complete remission was associated with first relapses at pre-study sites in 5/30 (17%) instances, compared to 21/35 (60%) in sites not receiving radiotherapy. Side-effects were commensurate with the intensity of the treatment program and are detailed in the text. Although the achievement of a high complete remission rate is promising, the failure to extend their duration beyond that of historical data suggests that additional conceptual and therapeutic approaches need to be explored.

Altretamine↗

PubMed1985

Consideration of covariates and stratification in sample size determination for survival time studies.

Sample size determination for survival time studies is discussed, taking into account stratification. We present formulas and tables which also apply in the case of multicenter clinical trials. In addition, the same method is used to estimate the sample size requirement when a covariate is grouped into strata. Simulation studies compare the results to covariate adjustment by the Cox proportional hazards model.

Follow-Up Studies↗