Search PubMed⌕ Search

Biomedical subjects

R Rasmussen

Publications and source records attributed to R Rasmussen.

42 records · Page 3Linked to original sources
PubMedDate not supplied

Toxicity of chemical components of ambient fine particulate matter (PM 2.5) inhaled by aged rats.

The toxicity of two important chemical components of fine ambient particulate matter (PM 2.5)-ammonium bisulfate (ABS) and elemental carbon (C)-was studied using aged (senescent) rats. The study tested the hypotheses that fine particle exposure can damage lungs and impair host defenses in aged rats and that ozone would potentiate the toxicity of these particles. Ammonium bisulfate aerosols were generated by nebulization of dilute aqueous solutions. Elemental carbon was generated from an aqueous suspension of carbon black. Carbon and ABS mixtures were generated by nebulization of a suspension of carbon black in a dilute aqueous solution of ABS. Rats were exposed, nose-only, for 4 h a day, three consecutive days a week, for 4 weeks. The rats were exposed to one of six atmospheres: (1) purified air; (2) C, 50 microg m(-3), 0.3 microm mass median aerodynamic diameter (MMAD); (3) ABS, 70 microg m(-3), 0.3 microm MMAD; (4) O3, 0.2 ppm; (5) ABS + C, 0.46 microm MMAD; and (6) ABS + C + O3, 0.45 microm MMAD. Data were analyzed using ANOVA and Tukey multiple comparison tests; a two-tailed significance level of 0.05 was used. The nuclei of lung epithelial and interstitial cells were examined to determine the labeling of the DNA of dividing cells by 5-bromo-2-deoxyuridine and to identify the location of injury-repair-related cell replication. Increased labeling of both epithelial and interstitial lung cells occurred following all pollutant exposures. Although epithelial cells are most likely impacted by inhaled particles first, the adjacent interstitial cells were the cells that showed the greatest degree of response. Exposure to the ABS + C + O3 mixture resulted in losses of lung collagen and increases in macrophage respiratory burst and phagocytic activities that were statistically significant. Our results demonstrate that ozone can increase the toxicity of inhaled particles (or vice versa), and suggest that detailed study of mixtures could provide a more comprehensive understanding of the mechanisms by which inhaled pollutants adversely affect human health.

Aerosols↗
PubMedDate not supplied

A regional study of sources of apathy toward membership in the American Society of Radiologic Technologists.

The problem of this study is to determine the reasons why registered technologists do not join The American Society of Radiologic Technologists (ASRT). This was accomplished with an instrument developed by the authors using a modified Delphi Technique and a five item Likert scale. A stratified random sample of technologists was selected from the Houston area to response to the instrument.

Attitude of Health Personnel↗
PubMedDate not supplied

Variability in creatinine clearance (CCR) and KT/V due to different methods of calculating volume and CCR.

OBJECTIVE: This study aimed to compare the correlations between KT/V and creatinine clearance (Ccr) calculated by different methods and to determine and compare the correlations between KT/V and Ccr. DESIGN: Nonrandomized, retrospective analysis of data. SETTING: Continuous ambulatory peritoneal dialysis (CAPD) outpatient clinic in a teaching hospital. PATIENTS: All patients were included for analysis if the data collection was complete for the calculations of KT/V and Ccr using five different methods. INTERVENTIONS: Volume of distribution for urea (V) was estimated by four methods: Watson nomogram, ideal body weight (IBW), actual body weight, and total body surface area. Ccr was determined by five methods: Dialysate Ccr was calculated by creatinine (Cr) uncorrected and corrected for the presence of glucose; urinary Ccr was calculated using urinary Cr alone and the average urinary clearance of urea and Cr; and by the Cockcroft and Gault method. MAIN OUTCOME MEASURES: Correlations between KT/V and Ccr. RESULTS: Sixty-three data sets were collected from 52 CAPD patients. The correlations between weekly KT/V and Ccr normalized to 1.73 m2 body surface area were found to be highly variable from one method to another (r2 = 0.012 -0.494). For obese patients (20% above IBW), KT/V values obtained were more variable using the Watson nomogram compared to the IBW and BSA methods. CONCLUSION: KT/V calculated using the Watson nomogram and the Ccr determined using average of urinary urea and creatinine clearance gave the best correlation (r2 = 0.49).

Body Constitution↗