The use and effectiveness of electrocardiographic telemetry monitoring in a community hospital general care setting.

UNLABELLED: The purpose of this study was to determine if rates of telemetry events differ between patients whose monitoring is appropriately "indicated" versus "not indicated" by systematically applying rigorous criteria for appropriateness of electrocardiogram (ECG) telemetry usage. We performed a retrospective cohort study on 1097 telemetry admissions between January 1, 2000 and March 31, 2000. A convenience sample of 218 patients generated 236 telemetry admissions. One-hundred-sixty-two arrhythmic events were detected during 400 "indicated" telemetry days. Nine arrhythmic events were detected during 345 "not indicated" telemetry days. The relative rate for arrhythmic events was significantly different, at P < 0.0001, with the incidence rate ratio of 15 indicating a very large effect size. Consequently, current use of ECG telemetry may not be optimal, and a prospective analysis of the application of rigorous indications for ECG telemetry needs to be undertaken. IMPLICATIONS: The application of standard criteria to electrocardiogram telemetry admissions found that the majority of abnormal heart rhythms were found when patients met appropriate criteria.

Radiation risk estimation in human populations: lessons from the radiological accident in Brazil.

The development of radiological and nuclear technologies and the deployment of nuclear weapons have made ionizing radiation one of the most studied human mutagens. Exposure to ionizing radiation produces DNA damage which can result in mutation and cancer, making the risk associated with human exposure a critical issue. In this paper we estimate the risk associated with radiation exposure for individuals exposed to 137Cs during the 1987 Goiânia radiological accident. Using combined regression slopes from both the in vivo hprt mutant frequency and micronucleus frequency data we estimated a doubling dose of 173 (+/-47) cGy for these two endpoints. This is in close agreement with the published estimates for low dose rate and chronic exposure to low-LET radiation. We obtained risk estimates of about 24-fold increase in dominant disorders in the post-exposure generation of the directly exposed population. No detectable increase was found in the population at large. The risk of carcinogenesis in the directly exposed population was found to be increased by a factor in the range of 1.4 to 1.5. The small sample size in this study requires a large element of caution with respect to risk estimates interpretation. Moreover, the doubling dose estimates prepared here are derived from lymphocytes. This somatic data may require additional considerations for both cancer and certainly germ-line events. Nevertheless, the risk of carcinogenesis and genetic harm for this population are good indicators of the potential genetic damage imposed by ionizing radiation to the Goiânia population.

Molecular analysis of T-lymphocyte HPRT- mutations in individuals exposed to ionizing radiation in Goiânia, Brazil.

We have characterized 54 HPRT- point mutations in T-lymphocytes from 17 individuals exposed to ionizing radiation of 137Cs in Goiania, Brazil and compared this spectrum to that of 30 HPRT- mutants from 9 unexposed Brazilian controls. The average internal exposure of the exposed group was 205 mCi, and the average external exposure was 1.7 Gy. The average HPRT- mutant frequency for the exposed group was 13.3 x 10(-5), approximately a 10-fold increase over the mutant frequency of the unexposed controls, which was 1.56 x 10(-5). The types of point mutations characterized included base substitutions, small deletions, frameshifts, insertions, complex mutations, and losses of exon sequences from the mRNA. The relative frequency of the different mutation types was similar in the two studied groups. However, in our study the distribution of events within the hprt coding sequence seemed to cluster at the same regions of the gene. These observations imply that the hprt gene does not present a homogeneous target to radiation mutagenesis, and perhaps this class of information may be used to detect radiation exposure in human populations.

Increased hprt mutant frequencies in Brazilian children accidentally exposed to ionizing radiation.

We have examined the effects of ionizing radiation on somatic mutations in vivo, using the hprt clonal assay. The study was performed on blood samples obtained from children exposed during a radiological accident that happened in 1987, in Goiânia, Brazil. The group of children exposed to ionizing radiation includes six males and four females ranging in age from 6 to 14 years at the time of exposure. The radiation doses ranged from 15 to 70 cGy. A Brazilian control group, not exposed to ionizing radiation, was also analyzed under similar conditions. the mean hprt mutant frequency for the exposed group was 4.6 times higher than the control group, although the cloning efficiency from the exposed group was significantly reduced. Linear regression analysis of the mutant frequency and ionizing radiation dose did not show a significant relationship between these two parameters. However, a reliable inverse relationship was demonstrated when the regression analysis was performed with nonselective cloning efficiency and ionizing radiation dose. It was demonstrated that nonselective cloning efficiency diminishes as ionizing radiation dose increases. To correct mutant frequencies for clonal events, the clonal relationship between the hprt mutant clones was examined by T-cell receptor analysis. The majority of the mutants analyzed represented individual clones, thus validating the observed mutant frequencies.

Monitoring hprt mutant frequency over time in T-lymphocytes of people accidentally exposed to high doses of ionizing radiation.

Modern technologies have provided the opportunity to monitor mutations in people in vivo. The subjects of this study were accidentally exposed to 137Cesium in a radiological accident that occurred in September 1987 in Goiânia, Brazil, during which more than 150 people received doses greater than 0.1 Gy and as high as 7 Gy. The objective of this study was to determine how long the hprt mutant T-cells in the peripheral blood contribute to mutant frequency by examining the time-course of the T-lymphocyte response to ionizing radiation. This report describes the results obtained over a period of 2.3 to 4.5 years subsequent to the accident, from 11 subjects with doses ranging from 1 to 7 Gy, and from nine control subjects selected from the same population. The mean In MF (+/- SE) of the control group was 2.5 (+/- 0.2) + In10(-6). The exposed group had a significantly increased mutant frequency; the mean In MF (+/- SE) were 3.3 (+/- 0.3) + In10(-6), 2.8 (+/- 0.2) + In10(-6), and 2.3 (+/- 0.2) + In10(-6), in the years 1990-1992 respectively. Based on the decline of mutant frequency and using Buckton's models [Buckton et al. (1967): Nature 214:470-473], we demonstrated that mutant T-cells have a short-term memory with a half-life of 2.1 years. This relatively short half-life limits the effective use of the hprt assay as the method of choice to monitor past exposure. The data also demonstrate a positive correlation with age, and an inverse correlation with plating efficiency.

The relationship between apartment living and fertility for blacks, Mexican-Americans, and other Americans in Racine, Wisconsin.

Recently published data from a sample of Bogotá, Colombia public housing residents show that apartment dwellers, but not house dwellers, reduced their fertility in a tight housing market. We propose that the utility-cost theory of fertility accounts for this finding, and, using this theory, we predict that (a) apartment residents will not decrease their fertility in an open housing market and (b) higher fertility will be associated with larger dwellings. Longitudinal data from a sample of Midwest urban blacks, Mexican-Americans, and other Americans support both predictions. The substantive implications are discussed.