Biomedical subjects

J A Deddens

Publications and source records attributed to J A Deddens.

13 recordsLinked to original sources

PubMed1998

Immunologic findings among lead-exposed workers.

A comprehensive panel of immune parameters was evaluated among 145 lead-exposed workers with a median blood lead level (BLL) of 39 micrograms/dL (range: 15-55 micrograms/dL) and 84 unexposed workers. After adjusting for covariates, we found no major differences in the percentage of CD3+ cells, CD4+ T cells, CD8+ T cells, B cells, or NK cells between lead-exposed and unexposed workers, although the association between lead exposure and the number of CD4+ T cells was modified by age. We also found no differences between exposed and unexposed workers in serum immunoglobulin levels, salivary IgA, C3 complement levels, or lymphoproliferative responses. However, among exposed workers, the percentage and number of B cells were positively associated with current BLL, serum IgG was negatively associated with cumulative lead exposure, and the percentage and number of CD4+/CD45RA+ cells were positively associated with cumulative lead exposure. We found no evidence of a marked immunotoxic effect of lead at the exposure levels studied, although some subtle differences in immunologic parameters were noted.

Adult↗

PubMed1998

Modifiers of lung cancer risk in uranium miners from the Colorado Plateau.

Given the scientific consensus that exposure to radon decay products causes lung cancer, most recent studies have focused on the nature of the exposure-response relationship. Since residential radon exposure is now a primary public health issue, a better understanding of the effects of low levels of radon as well as factors modifying risk estimates has become very important. Several factors are shown to affect risk estimates in the latest update of the vital status follow-up (through 1990) and smoking history for the cohort of underground uranium miners in the Colorado Plateau. This analysis confirms earlier results indicating a strong dependence of relative risk estimates upon attained age. Quantitative estimates of relative risk as a function of cumulative exposure to radon decay products (WLM) are provided for three age strata. The non-linearity often reported in the Colorado Plateau data is shown to be at least partially due to an inverse exposure-rate effect, i.e., low exposure rates for long periods are more hazardous than equivalent cumulative exposure received at higher rates for shorter periods of time. However, this effect is shown to diminish at lower exposure rates and cumulative exposures. In addition, use of the new smoking data indicates that the radon/smoking interaction is submultiplicative and may depend upon attained age.

Aged↗

PubMed1997

Increased precision using countermatching in nested case-control studies.

Nested case-control studies in occupational cohorts are often used to estimate exposure effects when development of detailed exposure estimates for all cohort members is too costly. Duration of exposure, which can act as a surrogate for cumulative exposure, is often readily available for all cohort members. Langholz and others have recently proposed a method of control selection called countermatching, which uses data on the surrogate to determine which controls are selected from the risk set for a given case. This method may increase precision relative to the usual random sampling of the risk set. We compare countermatching with random sampling in a nested case-control study of silicosis among miners. Data on cumulative exposure were in fact available for all cohort members, enabling estimation of the parameter of interest in the full cohort. We conducted nested case-control analyses using 100, 20, 10, and 3 controls per case using random sampling and additional analyses using 3 controls per case with two different methods of countermatching. All analyses were replicated 50 times to explore the statistical properties of the estimated exposure parameter. We found that one of the countermatching methods markedly increased efficiency compared with random sampling. Countermatching using 3 controls per case yielded an approximate 25% increase in relative efficiency compared with random sampling; it was approximately equivalent to random sampling using 10 controls.

Case-Control Studies↗

PubMed1997

Effect of travel and rest on performance of professional basketball players.

We have studied 8,495 regular season games in the National Basketball Association over eight seasons (1987-1988 through 1994-1995) to analyze the effects of travel and rest on performance. We found that more time between games improved performance, an effect that was constant over time and statistically significant. More than 1 day between games increased the home team's score by 1.1 points and the visitor's by 1.6 points. Peak performance occurred with 3 days between games. The negative effects of little time between games may be due to lack of time for physical recovery, rather than any effects of circadian rhythm (jet lag). We found few consistent effects of distance traveled or direction of travel. We did find a suggestion of circadian rhythm effects in a subanalysis of games on either coast in which the visitor traveled across the country, while the home team did not travel (n = 101). In these games, the visiting team did four points better (p = 0.07) when they traveled west to east rather than east to west, almost nullifying the home-court advantage. This effect, like similar findings for Monday Night Football games, may be due to West Coast visitors playing night games at an earlier time according to their "internal clock". An incidental finding in our study was that the home-court advantage decreased over 8 years, from about six points to three points (due to relatively lower field-goal percentages and fewer free throws by the home team).

Basketball↗

PubMed1997

Validation of the galactose oxidase-Schiff's reagent sequence for early detection and prognosis in human colorectal adenocarcinoma.

Based on the multistage and multifocal nature of colorectal carcinogenesis, it is likely that reduction of cancer mortality through early detection and identification of new prognostic markers is an attainable goal. Well-documented changes occur in mucin glycoconjugates during neoplastic progression in the colon, and the nonneoplastic colonic mucosa in colon cancer patients is morphologically and histochemically abnormal. In this retrospective study, 152 archival colorectal tissues from 49 patients were studied for changes in mucin secretions as detected by the galactose oxidase-Schiff's (GOS) sequence. Intensity of the stain was evaluated in histological sections by semiquantitative analysis, and the area percentage of epithelium stained was quantified by image cytometry. The correlation between gender or tumor size, location and reactivity with peanut agglutinin and quantitative expression of GOS-reactive mucins was determined as well as intratumor and inter individual variability. Reactivity with GOS: (a) decreased during neoplastic progression and malignant conversion in the neoplasm; (b) increased in the normal colonic mucosa of patients with progressively more advanced disease; and (c) was of prognostic significance for patient survival or recurrence both in the normal colon of cancer patients and in invasive neoplasms. These data are consistent with the conclusion that GOS reactivity in the normal colonic mucosa is a dosimeter of exposure to environmental/lifestyle colorectal carcinogens rather than a marker for an oncodevelopmental cancer-associated antigen.

Adenocarcinoma↗

PubMed1996

Elevated symptom prevalence associated with ventilation type in office buildings.

The California Healthy Building Study was designed to assess relations between ventilation system type and office worker symptoms in a set of U.S. buildings selected without regard to worker complaints. Twelve public office buildings in northern California meeting specific eligibility criteria were studied in the summer of 1990: three naturally ventilated, three mechanically ventilated (without air conditioning), and six air-conditioned buildings. Questionnaire data were collected from 880 workers in selected spaces within the study buildings. We adjusted effect estimates for various ventilation types for personal, job, and work place factors using logistic regression, and alternatively, using a mixed effects model (SAS/GLIMMIX) to adjust for correlated responses within study spaces. Higher adjusted prevalences of most symptom outcomes were associated with both mechanical and air-conditioned ventilation, relative to natural. With a conservative adjustment for problem building status, the highest adjusted prevalence odds ratios from logistic regression models were for dry or itchy skin [mechanical: odds ratio (OR) = 6.0, 95% confidence interval (CI) = 1.6-22; air-conditioned: OR = 6.0, 95% CI = 1.7-21] and lower respiratory symptoms (mechanical: OR = 2.9, 95% CI = 0.7-11; air-conditioned: OR = 4.0, 95% CI = 1.1-15). GLIMMIX estimates were similar, with slightly wider confidence intervals. Reporting bias was small. These findings of symptom increases within mechanically ventilated and air-conditioned U.S. buildings support previous findings available only from European buildings.

Adult↗

PubMed1995

Mortality among Navajo uranium miners.

OBJECTIVES: To update mortality risks for Navajo uranium miners, a retrospective cohort mortality study was conducted of 757 Navajos from the cohort of Colorado Plateau uranium miners. METHODS: Vital status was followed from 1960 to 1990. Standardized mortality ratios were estimated, with combined New Mexico and Arizona non-White mortality rates used for comparison. Cox regression models were used to evaluate exposure-response relationships. RESULTS: Elevated standardized mortality ratios were found for lung cancer (3.3), tuberculosis (2.6), and pneumoconioses and other respiratory diseases (2.6). Lowered ratios were found for heart disease (0.6), circulatory disease (0.4), and liver cirrhosis (0.5). The estimated relative risk for a 5-year duration of exposure vs none was 3.7 for lung cancer, 2.1 for pneumoconioses and other respiratory diseases, and 2.0 for tuberculosis. The relative risk for lung cancer was 6.9 for the midrange of cumulative exposure to radon progeny compared with the least exposed. CONCLUSIONS: Findings were consistent with those from previous studies. Twenty-three years after their last exposure to radon progeny, these light-smoking Navajo miners continue to face excess mortality risks from lung cancer and pneumoconioses and other respiratory diseases.

Adult↗

PubMed1994

Pancreatitis in patients with end-stage renal disease.

In a population of 716 patients with end-stage renal disease (ESRD), 46 patients (6.4%) were identified as having pancreatitis. Pancreatitis was significantly more common in those with alcohol abuse, systemic lupus erythematosus (SLE), and polycystic kidney disease. It was not significantly associated with hyperlipidemia, biliary tract disease, or hypercalcemia. Acute pancreatitis occurring before the patient developed ESRD was mainly alcohol-related and did not appear to be a significant risk factor for future episodes of pancreatitis during dialysis. Chronic calcific pancreatitis diagnosed before ESRD was almost invariably due to alcohol abuse, and tended to be a marker for recurrent acute exacerbation after development of ESRD, whether alcohol consumption continued or not. Pancreatitis occurring for the first time after ESRD in patients on dialysis was generally benign, and was usually accompanied by an uneventful recovery and few recurrent episodes. However, a significant elevation of the calcium x phosphate product was observed in these patients, occurring in about half the patients without any known precipitating factor. After kidney transplantation, the development of pancreatitis was associated with higher morbidity and mortality. Chronic calcific pancreatitis diagnosed after ESRD occurred only in patients with SLE; reported here for the first time, it may be a manifestation of long-standing disease, chronic steroid therapy, or both.

Acute Disease↗

PubMed1993

A case study of a recent decline in the dialysis fatality rate.

Geoffrey Berlyne, whom we honor in this Festschrift, has contributed much to the modern understanding of diseases of the kidney, and of the clinical and metabolic disorders that occur in acute and chronic renal failure. The Festschrift highlights the many areas of his contributions. It is important to note that underlying them all is astute clinical observation, incisive analysis and reasoning, a breadth of approach, experimentation that facilitated understanding of the relevant clinical issues, and an unusual clarity of exposition in the literature. As author, editor, and teacher, Geoffrey Berlyne has brought this clarity of approach to a generation in nephrology. The following analysis of clinical data from a working dialysis unit, rendering care to a predominantly underprivileged patient population, is presented in the hope that it throws light on everyday problems in nephrology in a manner similar to that in which Geoffrey has guided the nephrology community.

Case-Control Studies↗

PubMed1990

Clinicians' self-reported reactions to psychiatric emergency patients: effect on treatment decisions.

Masters-level social work clinicians at two urban psychiatric emergency services self-rated their cognitive reactions and conscious feelings toward a total of 783 patients. Negative self-reported affect toward patients was related to their displaying overt psychotic symptoms, having a final diagnosis of substance abuse, being impulsive, unemployed, or having a history of criminal behavior. However, clinicians' reactions did not enter into the model predicting hospitalization, which included opinion of family and friends, degree of psychopathology, suicidal ideation and lack of social supports as the major predictors of whether or not a patient would be hospitalized.

Adult↗

PubMed1989

The psychiatric emergency service holding area: effect on utilization of inpatient resources.

This study compared the rates of hospitalization from two psychiatric emergency services which were similar except that one service had an extended evaluation unit, or holding area, allowing up to 24 hours of evaluation. The rate of hospitalization from the service with the extended evaluation unit was 36%; the rate from the other service was 52%. The difference in admission rates was related to the availability of the extended evaluation unit, which made it possible for many patients to avoid rather than merely postpone admission to the hospital. Clinical determinants of admission and of successful treatment in the unit were also reviewed.

Adolescent↗

PubMed1985

Results of treatment in patients with end-stage renal disease: a multivariate analysis of risk factors and survival in 341 successive patients.

Factors that affect survival in patients with end-stage renal disease (ESRD) are still only partially understood. We report an analysis on a cohort of 341 successive patients who started ESRD treatment in one institution. Survival was calculated from the start of ESRD treatment, whether initial treatment was by dialysis (335 patients) or transplantation (6 patients). Analysis of factors affecting survival was done using the Cox multivariate hazard analysis. Relative risks were calculated for several demographic factors, the primary renal disease, the presence or absence of various high-risk co-morbid factors, and for a first transplant from a living-related or cadaver donor. Older patients, patients with no prior health insurance, those with diabetic nephropathy, and those with small kidneys of unknown cause had statistically significantly higher risks of dying. The risk of dying decreased by year of start of ESRD treatment. Living related donor transplantation was associated with a decreased hazard to age 45 years and older; whereas cadaver donor transplantation was associated with a hazard that increased with age and was significantly increased by age 45.

Actuarial Analysis↗

PubMedDate not supplied

Quantitative sonographic feature analysis of clinical infant hypoxia: a pilot study.

PURPOSE: To determine whether textural features derived from sonographic pixel intensities differ significantly between healthy infants and infants who have had acute clinical hypoxic episodes. METHODS: Neurosonographic and calibration phantom-processed image data were evaluated prospectively from 9 infants (age range, 1 to 163 days) with at least 1 episode of hypoxia and compared with image data from a control population of 16 healthy infants (age range, 1 to 191 days). Custom software was used to make 45 textural feature measurements on 40 x 40-pixel regions of interest within brain parenchyma in the distribution of each major cerebral artery, the thalami, and the cerebellum and in a tissue-mimicking calibration phantom. Means comparison testing was followed by logistic regression to assess statistical variation between the patients and the control group. RESULTS: Nine of 45 textural features showed statistically significant differences between mean values comparing the two groups. Mean gray level was the most sensitive predictor of differences between the two populations (mean gray level for healthy subjects was 46.8; mean gray level for patients was 56.3). An average of mean gray values in areas supplied by the posterior cerebral arteries and the cerebellum was even more sensitive for differentiating healthy subjects from patients. CONCLUSIONS: Quantitative sonographic textural feature analysis showed differences between the brains of healthy infants and those of infants with clinical hypoxia.

Asphyxia Neonatorum↗