Dynamic monitoring of the dust pickup efficiency of vacuum cleaners

This study evaluated a new method that uses an optical aerosol photometer for dynamically monitoring dust pickup efficiency during vacuuming. In the first stage of this study the new method was compared with built-in dirt sensors installed by vacuum cleaner manufacturers. Through parallel testing it has been shown that the widely available built-in dirt sensors are not sensitive enough to register small (< 53 microm) dust particles. Therefore, only the optical photometer was used in the rest of the experiments of this study to monitor the dust pickup efficiency while the vacuum cleaner was operated with different nozzles on clean and soiled carpet and vinyl sheet flooring. This method also was used to monitor dust pickup efficiency when vacuuming carpets originating from lead-contaminated homes. The dust pickup efficiencies obtained with the optical aerosol photometer have been compared with the surface lead concentrations found during different stages of cleaning. Results indicate that the dust mass concentration registered with the optical aerosol photometer at the nozzle outlet correlates well with the dust mass collected in the vacuum cleaner filter bag and with the surface lead level. Therefore, dynamic dust pickup monitoring can provide valuable information about the efficiency of cleaning when a vacuum cleaner is used. This suggests that a small aerosol photometer similar to a light-scattering smoke detector would be beneficial in vacuum cleaners used for cleaning surfaces contaminated with leaded dust and biological particles (including allergens).     

Survival of mycobacteria on N95 personal respirators.

OBJECTIVES: The overall aim of this study was to investigate the survival and possible growth of Mycobacterium tuberculosis simulant bacteria on respirator filters. METHODS: Mycobacterium smegmatis was used as a biochemical simulant for M tuberculosis. Bacterial survival was tested on National Institute for Occupational Safety and Health-certified N95 respirators from three manufacturers. The first experiments simulated one-time respirator use and subsequent storage for 1 to 9 days under ideal conditions for the growth of mycobacteria: 37 degrees C and 85% relative humidity. The bacteria were loaded on the respirator filters under three different nutritional conditions: in the absence of nutrients; in the presence of human saliva (simulating conditions when the respirator is worn); and in the presence of nutrient broth (for ideal growth potential). The subsequent experiments simulated respirator wear for 2 hours under medium work-load conditions at a breathing rate of 56 L/min. RESULTS: It was found that M smegmatis did not grow on the tested respirators, even when the respirators were stored at temperature, humidity, and nutrition conditions most favorable for microbial growth. However, these bacteria could survive on respirators for up to 3 days during storage. The culturability of M smegmatis was not affected by airflow that simulated the breathing rate associated with medium work-load conditions for 2 hours. CONCLUSIONS: This study shows that M tuberculosis surrogate bacteria collected on a respirator are not able to grow and are able to survive only in ideal (ie, not clinically relevant) conditions. Based on these experiments, we conclude that M tuberculosis is unlikely ever to become an infectious problem in the air again, once it is removed by a respirator.     

In Vitro Inhibition of Thyroid Hormone Sulfation by Polychlorobiphenylols: Isozyme Specificity and Inhibition Kinetics

It was recently demonstrated by our laboratory that hydroxylatedmetabolites of polychlorinated biphenyls (PCB-OHs) are inhibitorsof thyroid hormone sulfation. In this study, a more detailedinvestigation on sulfotransferase isozyme specificity and thekinetics of inhibition was performed. Thyroid hormone sulfationwas determined using 3,3'-diiadothyronine (T2) as a substrate,and various sources of sulfotransferase (SULT) enzyme were used;e.g., female and male rat liver cytosol, male brain cytosoland cytclsolic preparations of V79 cells transfected with ratSULT1C1, and human SULT1A1 and human SULT1A3. The inhibitionpattern and IC50 values were very similar for male and femalerat liver and rSULT1C1 and hSULT1A1. PCB-OHs were not able toinhibit the T2 sulfotranferase activity using hSULT1A3. Metabolite3-hydroxy-2,3',4,4',5-pentachlorobiphenyl did not inhibit T2sulfotransferase activity in male brain cytosol, while it wasa very potent inhibitor in male and female rat liver cytosol.IC50 values for the tested PCB-OHs were not different with eitherT2 or 3,3',5-triiodothyronine (T3) as substrate, supportingthe hypothesis that T2 is the preferred iodothyronine substratefor the sulfotransferases catalyzing the sulfation of the activehormone T3. The Lineweaver-Burk plot obtained with rat livercytosol and T2 suggested that the nature of the T2 sulfationinhibition by 4-hydroxy-2',3,3',4',5-pentachlorobipheny is competitive.Finally, it was demonstrated that tested hydroxylated polychlorinateddibenzo-p-dioxins and biphenyls were, albeit poorly, sulfatedby sulfotransferases as measured by the production of ³⁵S-labeledmetabolites.     

Longitudinal evaluation of cytogenetic aberrations in prostatic cancer: tumours that recur in time display an intermediate genetic status between non-persistent and metastatic tumours

Only limited data are available on chromosomes specifically involved in prostatic tumour progression. This study has evaluated the cytogenetic status of primary prostatic carcinomas, local tumour recurrences, and distant metastases, representing different time points in prostatic tumour progression. Interphase in situ hybridization (ISH) was applied with a set of (peri) centromeric DNA probes, specific for chromosomes 1, 7, 8 and Y, to routinely processed tissue sections of 73 tumour specimens from 32 patients. Longitudinal evaluation was possible in 11 cases with local recurrence and nine cases with distant metastases. The remaining 12 patients showed no evidence of local recurrence or distant metastasis after radical prostatectomy on follow-up (mean 60·5 months) and served as a reference. Numerical aberrations of at least one chromosome were found in 27 per cent of the local recurrences and 56 per cent of the distant metastases. In decreasing order of frequency, +8, +7, and −Y were observed in the recurrences, and +8, +7, −Y, and +1 in the distant metastases. Evaluation of the corresponding primary tumour tissue of the recurrence group showed numerical aberrations in 45 per cent of cases. The aberrations found were, in decreasing order of frequency, −Y, +7, and +8. In the concomitant primary tumour tissue of the distant metastasis group, numerical aberrations were detected in 67 per cent of cases. The aberrations most frequently encountered were +8, −Y, followed by +7. In four cases, a concordance was found between the primary tumour and its recurrence or distant metastasis. Discrepancies might have been caused by cytogenetic heterogeneity. Comparison of the primary tumour tissue of the reference, the recurrence, and the distant metastasis groups showed a significant increase for the percentage of cases with numerical aberrations (P_trend=0·02). Likewise, a trend was seen for gain of chromosome 7 and/or 8 (P_trend<0·05). The number of DNA aneuploid tumours also increased in these different groups (P_trend=0·03). These data suggest that cancers which recur in time display an intermediate position between tumours of disease-free patients and metastatic cancers. © 1998 John Wiley & Sons, Ltd.     

The effect of aerosol size distribution and measurement method on respirator fit

The particle size-dependent leakage into a respirator was examined by measuring the leakage of particle sizes between 0.07 to 4.4 microns through three hole sizes in a negative-pressure half-mask respirator worn by a human subject. This investigation showed that the size distribution of an aerosol test agent and the measurement method have an effect on the leakage measured in a quantitative fit test. For instance, the ratio of percent leakage measured by light scattering between test aerosols with count median diameters of 2.2 and 0.28 microns can be as large at 5:1. Likewise, the ratio of the percent leakage measured by a particle count method vs. a mass method of detection of the same polydisperse aerosol with a count median diameter equal to 2.2 microns can be as high as 4:1. The mass leakage into a mask with a leak is also greater for an exposure aerosol with a count median diameter between 0.15 to 0.30 micron compared to exposure aerosols with larger count median diameters for aerosols with the same mass concentration.     

The vascular nurse in practice: results of prescribed exercise training in patients with intermittent claudication

Intermittent claudication (IC) is a mild stage of peripheral arterial disease that affects between 3% and 7% of the population and up to 1 in 5 patients over the age of 75 years. Risk factors such as hypertension, hyperlipidemia, diabetes, smoking, and genetics increase the incidence of peripheral arterial disease. Patients with IC have limitations in functional capacity and can benefit from regular exercise. Walking is the preferred mode of exercise and improves the symptoms of claudication in several ways. Vascular nurses can play an important role during exercise therapy. A personalized, home-based exercise program can be developed, and nurses can assist and motivate patients during follow-up periods. Helping patients to quit smoking and control other risk-factor modifications (ie, high blood pressure and lipid levels) also has high priority in daily practice of the vascular nurse. This prospective study will illustrate the results of prescribed home-based exercise training by a vascular nurse on the maximum painless walking distance for patients with IC and will be applied to subgroups of vascular pathology.     

A patient with de novo tuberculosis during anti-tumor necrosis factor-alpha therapy illustrating diagnostic pitfalls and paradoxical response to treatment.

In 2005, a 24-year-old man with Crohn disease who had been treated with infliximab for several months was exposed to an individual with smear-positive tuberculosis. Soon after exposure, he complained of malaise, dry cough, and weight loss. Despite normal chest radiograph findings and negative tuberculin skin test results, tuberculosis was considered to be the most likely diagnosis. The results of a whole-blood assay for detection of interferon- gamma production in response to Mycobacterium tuberculosis-specific antigen were positive. Acid-fast staining and polymerase chain reaction of bronchoalveolar lavage fluid samples had negative results, but M. tuberculosis was cultured. After the initiation of 4 antitubercular drugs and the discontinuation of infliximab therapy, the patient developed an immune reconstitution syndrome accompanied by enlarged mediastinal lymph nodes and multiple intrapulmonary miliary lesions. This case of de novo tuberculosis during anti-tumor necrosis factor alpha treatment illustrates the uncharacteristic presentation of the disease and the elusiveness of the diagnosis, as well as the fact that discontinuation of anti-tumor necrosis factor alpha treatment can be accompanied by an immune reconstitution syndrome similar to that observed in human immunodeficiency virus-infected individuals with tuberculosis.