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Biomedical subjects

S K Broste

Publications and source records attributed to S K Broste.

14 recordsLinked to original sources
PubMed1992

Relation between magnesium and potassium concentrations in myocardium, skeletal muscle, and mononuclear blood cells.

Potassium and magnesium were measured in 26 cardiac surgery patients (right atrial appendage), 23 autopsy subjects (right atrial appendage, left ventricular free wall, and skeletal muscle), and 9 healthy volunteers (mononuclear blood cells) to determine whether there was a relation between these two ions in the tissues measured. In the cardiac surgery patients, the potassium and magnesium concentrations were 46.35 +/- 3.89 and 4.40 +/- 0.58 (mean +/- SD, mumol/g wet weight tissue), respectively, and were significantly correlated (r = 0.54, P = 0.005). In the autopsy group, the respective concentrations were: for right atrial appendage, 30.54 +/- 10.18 and 3.66 +/- 0.70 mumol/g (r = 0.38, P = 0.14); left ventricular free wall, 60.69 +/- 17.93 and 7.74 +/- 1.73 mumol/g (r = 0.92, P = 0.0001); and skeletal muscle, 93.05 +/- 20.49 and 8.64 +/- 2.06 mumol/g (r = 0.91, P = 0.0001). In the healthy volunteer group, the results for potassium and magnesium in mononuclear blood cells were 42 +/- 9.9 and 3.99 +/- 0.70 fmol/cell, respectively (r = 0.94, P = 0.0001). Thus, potassium and magnesium concentrations were significantly correlated in all the tissues measured.

Aged↗
PubMed1992

ROC curve analysis: an example showing the relationships among serum lipid and apolipoprotein concentrations in identifying patients with coronary artery disease.

Clinical accuracy, defined as the ability to discriminate between states of health, is the fundamental property of any diagnostic test or system. It is readily expressed as clinical sensitivity and specificity, and elegantly represented by the receiver operating characteristic (ROC) curve. To demonstrate the use of ROC curves, we reexamine a study of the ability of serum lipid and apolipoprotein measures to discriminate among degrees of coronary artery disease in patients undergoing coronary angiography. ROC curve analysis reveals that none of these indexes is highly accurate, but demonstrates a modest increase in the accuracy of apolipoprotein over lipid indexes.

Apolipoproteins↗
PubMed1991

Myocardial magnesium: relation to laboratory and clinical variables in patients undergoing cardiac surgery.

Magnesium concentration was measured in the right atrial appendage of 100 patients undergoing cardiac surgery and associations with serum and mononuclear blood cell magnesium, other laboratory values and patient clinical variables were studied. In addition, magnesium was measured in the right atrial appendage and left ventricular free wall in 23 autopsy subjects to determine whether there was a proportional relation between right atrial appendage and left ventricular free wall magnesium. The mean left ventricular free wall/right atrial appendage magnesium ratio was 2.13 +/- 0.39 (r = 0.67, p = 0.0009). In the group with cardiac surgery, the right atrial appendage magnesium concentration correlated inversely with age (r = -0.54, p = 0.001). The mean right atrial appendage magnesium concentration (micrograms/g wet weight tissue) was lower in patients with postoperative cardiac arrhythmia than in those without arrhythmia (103 +/- 13 versus 111 +/- 10, p = 0.009) and in diabetic than in nondiabetic patients (103 +/- 13 versus 109 +/- 12, p = 0.02). The right atrial appendage magnesium concentration also tended to be lower in patients receiving potassium/magnesium-losing diuretics, although this difference did not achieve statistical significance (105 +/- 14 versus 109 +/- 11, p = 0.16). Right atrial appendage magnesium concentration correlated positively with serum creatinine concentration (r = 0.31, p = 0.002) and negatively with serum calcium concentration (r = -0.29, p = 0.013). Serum magnesium did not correlate with right atrial appendage or mononuclear blood cell magnesium concentration or clinical variables. There was a statistically significant correlation between mononuclear blood cell and right atrial appendage magnesium concentrations in some subgroups of patients.

Aged↗
PubMed1991

The effect of epilepsy or diabetes mellitus on the risk of automobile accidents.

BACKGROUND: Previous studies of possible associations between chronic medical conditions and traffic safety have been inconsistent and subject to bias because of the incomplete identification of affected persons. Recent advances in the diagnosis and management of epilepsy and diabetes mellitus have improved the control of these disorders and suggest a need to reexamine the risk of traffic mishaps among patients with these conditions. METHODS: We conducted a population-based retrospective cohort study of 30,420 subjects 16 to 90 years of age, with and without epilepsy or diabetes mellitus. Subjects included all the licensed drivers in seven contiguous ZIP Code areas in which the Marshfield Clinic and St. Joseph's Hospital, Marshfield, Wisconsin, are the primary sources of medical care. Standardized rates of moving violations and accidents over a four-year period (1985 through 1988) were compared in affected and unaffected cohorts. RESULTS: Standardized mishap ratios for subjects with diabetes were 1.14 for all moving violations (P = 0.23) and 1.32 for accidents (P = 0.01); for subjects with epilepsy the ratios were 1.13 for moving violations (P = 0.26) and 1.33 for accidents (P = 0.04). CONCLUSIONS: We conclude that drivers with epilepsy or diabetes mellitus have slightly increased risks of traffic accidents as compared with unaffected persons. The increases in risk observed in our study were generally smaller than those in previous studies, and we believe they are not great enough to warrant further restrictions on driving privileges.

Accidents, Traffic↗
PubMed1991

Characteristics of alcohol use by school children in a northcentral Wisconsin county.

Before a school-based substance abuse prevention program was introduced, students in grades 5 through 12 in a northcentral Wisconsin county completed a questionnaire on their experience with tobacco, alcohol, and other drugs. Alcohol abuse was widespread, even among the youngest students surveyed. Commencement of alcohol use in the 5th grade or earlier appears to be increasing in recent years. There was a dose response relationship observed between the amount of alcohol consumed and the reported frequency of poor grades, thoughts and attempts of suicide, driving after drinking, remorse, and memory loss. Physicians caring for adolescents need to consider the possible role of alcohol abuse in a number of clinical situations. Because of their unique expertise and stature in the community, physicians also have an important role in community-oriented substance abuse prevention programs.

Adolescent↗
PubMed1990

Statistical methods in SUPPORT.

The analysis and interpretation of the data collected in SUPPORT provide great potential for understanding the relationships among treatment choices, patient and physician values and preferences, perceptions about the risks and benefits of treatments, institutional characteristics, and outcomes (as measured by quality of life, survival, and satisfaction). The complicated analyses required to elucidate these relationships will pose many technical challenges in dealing with longitudinal observational data collected from seriously ill patients at multiple sites. Major challenges include the handling of incomplete data, proper parameterization of treatment effects, strategies to avoid various potential biases, validating predictive models, and constructing endpoints that combine survival with quality of life. Within the structure of the SUPPORT study, mechanisms have been established to guide the analyses and to ensure their quality and validity.

Confounding Factors, Epidemiologic↗
PubMed1990

Apolipoproteins A-I and B as predictors of angiographically defined coronary artery disease.

Apolipoprotein A-I and B concentrations were measured in 502 patients undergoing diagnostic cardiac catheterization to assess the predictive power of apolipoproteins B and A-I to discriminate between patients with coronary artery disease and those with normal coronary arteries as defined by coronary arteriography. The strength of the associations was compared with that of the associations between traditional risk factors (eg, smoking status, cholesterol levels) and coronary artery disease. The study population consisted of 154 women (mean age, 62.9 years) and 348 men (mean age, 59.6 years). The apolipoprotein A-I concentration averaged (+/- SD) 124 +/- 25 mg/dL and the apolipoprotein B concentration, 98 +/- 24 mg/dL. In all cases, the apolipoprotein measures showed a larger univariate difference between the "normal" (no coronary artery disease) group (66 patients) and the group with coronary artery disease (436 patients) than did the corresponding standard lipoprotein measures. The variable with the strongest association with coronary artery disease was the ratio of apolipoprotein A-I to apolipoprotein B, followed by apolipoprotein B level. These findings were confirmed using logistic regression, adjusting for other coronary artery disease risk factors. Fasting status did not affect apolipoprotein A-I or B concentrations. We conclude that the use of apolipoprotein A-I and B concentrations gives additional information to that supplied by lipoprotein measures to help predict the presence of coronary artery disease. Since traditional lipid measures may be changed by a meal, apolipoproteins A-I and B might be more useful measures when the fasting status of a patient is in question.

Apolipoprotein A-I↗
PubMed1989

Carcinoma of the cervix and smoking.

There is considerable evidence from epidemiologic and clinical studies that cigarette smoking is associated with the risk of cervical cancer. Definitive clarification of whether this association is causal will likely have to await definitive identification of the sexually transmitted agent which is probably the most important cause of cervical cancer. Only then will it be possible to clarify the contributions of risk factors with weaker associations with cervical cancer, such as cigarette smoking and socioeconomic status.

Carcinoma, Squamous Cell↗
PubMed1989

Hearing loss among high school farm students.

To study the prevalence of hearing loss among teen-aged farm children in central Wisconsin, audiometric threshold testing of 872 vocational agriculture students was carried out over a three-year period. The results indicate an increased prevalence of hearing loss among students actively involved in farm work, as compared to their peers not involved in farm work. Findings also suggest that use of hearing protection may reduce the risk of hearing loss among students who work on the farm, although few students report the use of such devices. These data also suggest that the hearing loss often observed in adult farmers may begin in childhood.

Adolescent↗
PubMed1987

Extension of life-table methodology to allow for left-censoring in survival studies of pacing devices followed by commercial monitoring services.

The actuarial life-table is commonly used to describe lifetime data of living subjects and manufactured products. The life-table method allows subjects to come under observation at different times and, thus, to have differing lengths of follow-up, by assuming all subjects begin their lifetimes relative to the outcome of interest at some common point in time. As time progresses, subjects are withdrawn from the life-table when their period of observation has elapsed. This pattern of follow-up is often termed "right-censoring." An important feature of the classical life table approach is that the time at which the subject is placed at risk is known, and the status relative to the outcome of interest is known for the entire time at risk. Sometimes, however, subjects cannot be observed for some period after the beginning of their lifetimes. The example to be considered involves follow-up data collected by a commercial pacemaker monitoring service, to which patients subscribe, generally at some point following the actual implant of the pacemaker. Since the outcome of interest is device failure after implant, some means of dealing with the lack of information between implant and initiation of follow-up is needed. The extension of the actuarial life-table to accommodate this "left-censoring" will be described in this paper.

Actuarial Analysis↗
PubMed1986

A modified actuarial life-table approach to the analysis of implantable device performance.

The actuarial life-table method is often used by pacemaker manufacturers and the pacing research community to describe pacemaker and lead performance. Most life-table methods allow for differing lengths of follow-up but assume that all devices were followed from implant. Occasionally, however, devices come under follow-up observation sometime after implant. This presentation describes an extension of the actuarial method to accommodate these kinds of data. The specific example to be considered involves follow-up data collected by CardioCare, a commercial cardiac monitoring service, on the performance of Medtronic polyurethane leads. Patients subscribe to this service, generally at some time after actual device implant. Results showed that of 12,112 patients with Models 4002, 6971, and 6972 leads who were followed by CardioCare, only 85 were followed from implant. If one were to exclude patients not followed since implant, more than 99% of the data would be lost. Using the modified approach with allowance for postimplant, entry resulted in an estimated three-year cumulative survival probability for these leads of 95.7%. Treating all patients as if they were followed since implant, the probability would be 96.9%, an optimistic and biased estimate.

Actuarial Analysis↗