A cluster of VanD vancomycin-resistant Enterococcus faecium: molecular characterization and clinical epidemiology

VanD-mediated glycopeptide resistance has been reported for an isolate of Enterococcus faecium, BM4339. Three clinical isolates of vancomycin-resistant E. faecium collected from 3 patients during a 6-week period in 1993 had agar dilution MICs of vancomycin and teicoplanin of 128 and 4 microg/mL, respectively. Polymerase chain reaction (PCR) using degenerate primers complementary to genes encoding d-Ala-d-X ligases yielded a 630-bp product that was similar to the published partial sequence of vanD. By use of inverse PCR, vanD, vanHD, and two partial flanking open-reading frames were sequenced. The deduced amino acid sequence of VanD showed 67% identity with VanA and VanB. vanD appeared to be located on the chromosome and was not transferable to other enterococci. The 3 isolates were indistinguishable by pulsed-field gel electrophoresis and differed from BM4339. No other isolates carrying vanD were found in a subset of 875 recent US isolates of vancomycin-resistant enterococci.

Worker exposures to particulates, endotoxins, and bioaerosols in two refuse-derived fuel plants

Exposures of refuse-derived fuel (RDF) production workers to total particulates, endotoxin, and total (viable plus nonviable) bioaerosols were characterized at two RDF production plants. Full-shift personal air monitoring for 35 workers was conducted for total particulates, analyzed by gravimetric analysis; endotoxin, analyzed by chromogenic endpoint assay; and total bioaerosols, analyzed by fluorescent microscopy (FM). Geometric mean values of personal air samples were 0.50 mg/m3 for total dust, 29.0 EU/m3 (2.9 ng/m3) for endotoxin, and 6.8 x 10(5) organisms/m3 for bioaerosols. Significant differences were observed between the two plants only for total endotoxin exposures. The mean concentrations for total particulates, total FM bioaerosols, and endotoxins did not differ among the day, evening, or night shifts. Interjob differences were found for exposures to total dust, total endotoxin, and FM bioaerosols. Individual comparisons for total particulates and endotoxin exposures were significant for comparisons between job categories as a result of the greater exposures for personnel cleaning the plants. Significant correlations were detected between total particulates and total endotoxin measurements and between inhalable and total particulates.

Respiratory, gastrointestinal, and other health effects among workers in two refuse-derived fuel plants

This study was conducted to investigate health effects in workers at two refuse-derived fuel processing plants. Cross-shift pulmonary function testing and self reporting of symptoms from questionnaires formed the basis of a cross-sectional epidemiological study. Other topics addressed were exploration of the possibility of a hand to mouth component resulting in diarrhoea observed historically by the microbiological testing of skin. Symptoms of sinus trouble, headaches, nose irritation, and diarrhoea were reported by over 50% of the employees. Small, but statistically significant, cross-shift decrements of 1.50% and 2.01% were noted for forced vital capacity (FVC) and forced expiratory volume in one second (FEV1), respectively. Workers employed seven years or more had significantly larger cross-shift decrements in FVC and FEV1 than those employed for a shorter period. No active cases of diarrhoea were observed. Low lung function decrements characterise the observed workforce. Elevated reporting of some symptoms and a cross-shift decrement that increases with length of employment indicate that further study is warranted.

Potential significance of airborne fiber dimensions measured in the U.S. refractory ceramic fiber manufacturing industry

BACKGROUND

To determine dimensions of airborne fibers in the U.S. refractory ceramic fiber (RCF) manufacturing industry, fibers collected through personal air sampling for employees at RCF manufacturing and processing operations have been measured.

METHODS

Data were derived from transmission electron microscopy analyses of 118 air samples collected over a 20-year period.

RESULTS

Characteristics of sized fibers include: diameter measurements of <60; 0.19 to 1.0 micron, m of which 75% are less than 0.6 micron and length ranging from < 0.6 to > 20 micron, with 68% of fibers between 2.4 and 20 micron.

CONCLUSIONS

Exposures in RCF manufacturing include airborne fibers with dimensions (diameter < 0.1-0.4 micron, length < 10 micron) historically associated with biological effects in pleural tissues. Air sampling data and a review of studies relating fiber size to pleural effects in animals and humans support the belief that information on fiber dimensions is essential for studies with synthetic vitreous fibers.

Health care worker disability due to latex allergy and asthma: a cost analysis

OBJECTIVES

The reported prevalence of occupational allergy to natural rubber latex is 8% to 17%, and that of latex-induced occupational asthma is 2.5% to 6%. Conversion of medical facilities to "latex-safe" can reduce employee sensitization, impairment, and disability. The purpose of this study was to determine the cost of a latex-safe approach, compared with that of continued latex glove use, and to identify the level of worker disability required to make the latex-safe approach financially preferable to a health care institution.

METHODS

The costs of 2 strategies--latex-safe vs the status quo--were calculated from the perspective of 3 health care institutions. A break-even point was calculated for each facility.

RESULTS

In all facilities, the cost of using nonlatex gloves exceeded the cost of using latex gloves. In all 3 facilities, however, 1% or fewer of those at risk would have to become fully disabled or fewer than 2% would have to become partially disabled for the continued use of latex gloves to exceed the cost of the latex-safe approach.

CONCLUSION

Health care facilities, regardless of size, are likely to benefit financially from becoming latex-safe even if latex-related disability levels are extremely low.

Functional localization of a melanoma tumor suppressor gene to a small (< or = 2 Mb) region on 11q23

We have previously demonstrated the existence of a melanoma tumor suppressor gene(s) on the long arm of chromosome 11 through suppression of tumorigenicity assays. Although loss of heterozygosity studies also support this finding, only a large critical region (44 cM) has been identified to date on 11q22-25. To further localize a tumor suppressor gene(s) within this region, we have now generated and characterized nine melanoma microcell hybrids, each retaining an introduced fragment of 11q. Of the nine hybrids, four were suppressed for tumor formation in nude mice, while five formed tumors at the same rate as the parental melanoma cell line (UACC 903). Molecular analysis of the hybrids with 118 microsatellite markers narrowed the location of a putative suppressor gene to a small (< or =2 Mb) candidate region on 11q23 between the markers D11S1786 and D11S2077 and within the larger region frequently deleted in melanoma tumors and cell lines. While multiple tumor suppressor genes are likely to reside on 11q22-25, the presence of this region in all four suppressed hybrids supports the simplest model that a single locus is responsible for the suppressed phenotype observed in UACC 903.

Clinical practices in the management of new-onset, uncomplicated, low back workers' compensation disability claims

Recent consensus guidelines delineate what appears to be the most successful and cost-effective management of low back pain (LBP), and some recent studies have suggested that better outcomes occur with the least aggressive forms of medical intervention. The purpose of this study was to describe how practitioners manage new-onset, uncomplicated low back workers' compensation (WC) disability cases. A sample of cases was randomly selected from a large insurance carrier's national data source. An effort was made to select only uncomplicated cases, which would be expected to have relatively minimal need for medical intervention. There was an apparent overuse of diagnostic and treatment modalities. Diagnostic imaging was overutilized, not only in terms of the number of studies done (65% had plain films, 22% had magnetic resonance imaging scans) but also in the time frame in which they were performed (38% had plain films on the first clinic visit). Ninety percent received at least one medication, and 38% received more than one prescription for opioid analgesics. Expensive non-steroidal anti-inflammatory drugs were prescribed more often than acetaminophen (61% versus 6%, respectively). Sixty-two percent received physical therapy that often included modalities with as yet unproven efficacy. Overutilization of either diagnostic or treatment procedures increases the likelihood of iatrogenic complications, is not cost-effective, and may adversely impact clinical and occupational outcomes.

Comparison of NucliSens and Roche Monitor assays for quantitation of levels of human immunodeficiency virus type 1 RNA in plasma

We compared the performance of Organon Teknika's NucliSens and Roche Diagnostic Systems' Monitor quantitative human immunodeficiency type 1 RNA assays. Both had similar linearity and sensitivity over most of the dynamic range of the assays, although the Monitor assay was superior at the low range of RNA values while the NucliSens assay was more consistent at higher RNA values. NucliSens generally showed less interassay variability.

Association of actin filaments with axonal microtubule tracts

Axoplasmic organelles move on actin as well as microtubules in vitro and axons contain a large amount of actin, but little is known about the organization and distribution of actin filaments within the axon. Here we undertake to define the relationship of the microtubule bundles typically found in axons to actin filaments by applying three microscopic techniques: laser-scanning confocal microscopy of immuno-labeled squid axoplasm; electronmicroscopy of conventionally prepared thin sections; and electronmicroscopy of touch preparations-a thin layer of axoplasm transferred to a specimen grid and negatively stained. Light microscopy shows that longitudinal actin filaments are abundant and usually coincide with longitudinal microtubule bundles. Electron microscopy shows that microfilaments are interwoven with the longitudinal bundles of microtubules. These bundles maintain their integrity when neurofilaments are extracted. Some, though not all microfilaments decorate with the S1 fragment of myosin, and some also act as nucleation sites for polymerization of exogenous actin, and hence are definitively identified as actin filaments. These actin filaments range in minimum length from 0.5 to 1.5 microm with some at least as long as 3.5 microm. We conclude that the microtubule-based tracks for fast organelle transport also include actin filaments. These actin filaments are sufficiently long and abundant to be ancillary or supportive of fast transport along microtubules within bundles, or to extend transport outside of the bundle. These actin filaments could also be essential for maintaining the structural integrity of the microtubule bundles.

The use of TEPC for reference dosimetry

The radiation fields on board aircraft are quite complex and cover an energy range that is unusual in ordinary radiation protection work. Usually dosemeters measure only one radiation quality and the mixture found on board makes measurements complicated. There is also some doubt when it comes to the best choice of quantity for this application and no radiation standards exist for this kind of radiation field. For those reasons there is a need to find a standard measurement procedure that could serve as a reference for other, maybe simpler, measurements or for calculations of route doses. The only direct reading dosemeter that both measures the absorbed dose to tissue and the radiation quality (in terms of lineal energy) is the tissue-equivalent proportional counter (TEPC). The instrument was originally developed for scientific purposes and is still used as such. The detector consists of a gas filled cavity surrounded by a few mm thick wall. Both wall and gas consists of tissue-like material. The measurement principles are explained. Results observed with TEPC instruments are demonstrated. A preliminary collection of data reported by different groups from measurements on board aircraft will be shown. The results agree within +/- 20%. The conclusion is that TEPC instruments have the capacity of serving as reference instruments.

Physics of cosmic radiation fields

This paper glances at the knowledge of composition and energy spectra of galactic cosmic rays and briefly discusses the mechanism of solar modulation and of shielding against these particles by the earth's magnetic field. A short review of the properties of solar particle events is given, in which particles emitted from the sun enter the atmosphere. Particle production in the earth's atmosphere in hadronic and electromagnetic cascades is described and the altitude variations of the different particle components are investigated. Typical energy spectra in the atmosphere are presented for some types of particles.

Exposures of geotechnical laboratory workers to respirable crystalline silica

Geotechnical laboratory testing involves the determination of the physical properties of soil, rock, and other building materials for engineering purposes. Individuals working in these laboratories are exposed to airborne soil, rock, and other dusts during the preparation and testing of these materials. Crystalline silica as quartz is a common constituent of these materials and represents a potential hazard to geotechnical laboratory workers when airborne as a respirable dust. The authors conducted an examination of the potential for geotechnical laboratory workers to be exposed to respirable dust and respirable quartz during the performance of three routine laboratory tasks. A task-based exposure assessment strategy was used. Although respirable dust was generated during the performance of each of these tasks, its impact on exposures was generally overridden by the presence of respirable quartz in the dust. Quartz content in the respirable dust ranged from below the detection limit to greater than 50 percent. Mean exposure to respirable quartz, based on the duration of the task and assuming no other exposures for the rest of the 8-hour day, exceeded the National Institute for Occupational Safety and Health (NIOSH) "action level" (the exposure level at which certain actions must be taken) of 0.025 mg/m3. If exposure was assumed to continue for the rest of the 8-hour day at the measured concentration, mean exposure to respirable quartz exceeded the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) time-weighted average (TWA), the Occupational Safety and Health Administration (OSHA) PEL, and the NIOSH REL. Seven percent of 57 individual task exposure measurements exceeded the TLV-TWA and the PEL, 18 percent exceeded the REL, and another 12 percent exceeded excursion limits as defined by ACGIH. The results of this study support the conclusion that geotechnical laboratory workers are potentially exposed to respirable crystalline silica as quartz at levels that may be harmful. Because the quartz content of the materials being tested in these laboratories is highly variable and is almost never determined prior to testing, all materials being tested in the geotechnical laboratory should be assumed to contain quartz. Appropriate controls should be used to protect workers from inhaling dusts generated from these materials.

Plasma 5-aminolevulinic acid concentration and lead exposure in children

The relationship between concentration of 5-aminolevulinic acid in plasma (ALAP) and other biomarkers of lead exposure and effect was investigated in lead-exposed children. We measured ALAP by chemical derivatization and high-performance liquid chromatography with fluorescence detection. The study population consisted of 103 children: 78 from a referral clinic for children with lead poisoning and 25 from a general pediatric clinic. Blood lead concentration (PbB), age, and ALAP were higher in lead clinic subjects than in general clinic subjects. ALAP was significantly correlated with PbB (Spearman r=0.38, P=0.0007) and free erythrocyte protoporphyrin concentration (r=0.41, P=0.0002) in lead clinic subjects. PbB was a significant predictor of ALAP (P=0.0001) by multiple linear regression in all subjects. The average PbB in the 3- to 12-month period prior to blood collection correlated with ALAP to the same degree that current PbB correlated with ALAP. Possible associations between ALAP and adverse health outcomes, particularly neurobehavioral effects, should be investigated in children to assess the predictive value of ALAP for these endpoints.

Healthcare utilization and referral patterns in the initial management of new-onset, uncomplicated, low back workers' compensation disability claims

Most episodes of low back pain are considered non-specific in nature, with the vast majority resolving within 2 weeks and almost all resolving within 6 weeks regardless of the medical intervention. Recently published clinical guidelines have clearly delineated a limited set of circumstances that would indicate the need for specialist referral. The purpose of this study was to describe the healthcare utilization and physician referral patterns for new-onset, uncomplicated, low back workers' compensation disability cases randomly selected from a large insurance carrier data source. The provision of care in urgent care centers and emergency departments for both initial and main sources of care occurred more frequently than was probably indicated. For this selected group of uncomplicated low back pain cases, specialist care was provided more commonly than would be expected or indicated (36% of the sample was seen by a surgeon, while only 2% received surgery). In addition, referral to specialists (other than occupational medicine specialists) was often made sooner than would be expected or indicated, with a median of 13 days for such referrals. Such overutilization of resources can reasonably be expected to increase overall medical costs.

Hepatitis C virus E1 protein induces modification of membrane permeability in E. coli cells

The E1 gene of hepatitis C virus (HCV) has been cloned and expressed in BL21(DE3)pLys Escherichia coli strain by pET3a vector to analyze changes in membrane permeability produced by this protein. We showed that the expression of E1 (aa 192-383), as well as of two C-terminal fragments (aa 331-383 and aa 341-383) corresponding to the transmembrane (TM) region of this protein, induced a rapid lysis of cells. On the contrary, the expression of a mutant of E1 (aa 192-340), lacking the last 40 amino acids, did not cause cell lysis. The analysis of permeability changes revealed that modification of membrane permeability to several compounds were observed only in clones expressing E1 and C-terminal fragments, while the synthesis of the C-terminal-deleted mutant had little or no effect on permeability. These findings demonstrate that the TM domain of E1 protein has membrane-active properties that may be involved in some aspects of virus-cell interaction.

In vitro loss of heterozygosity targets the PTEN/MMAC1 gene in melanoma

Gross genetic lesions of chromosome 10 occur in 30-50% of sporadic human melanomas. To test the functional significance of this observation, we have developed an in vitro loss of heterozygosity approach in which a wild-type chromosome 10 was transferred into melanoma cells, where there was selection for its breakage and regional deletion to relieve its growth suppressive effects. The overlap of these events was at band 10q23, the site of the recently isolated PTEN/MMAC1 tumor suppressor gene, suggesting it as a potential target. Although the gene was expressed in the parental cells, both of its chromosomal alleles contained truncating mutations. In vitro loss of heterozygosity resulted in loss of the chromosomally introduced wild-type PTEN/MMAC1, and ectopic expression of the gene caused cell growth suppression. Thus, this approach identified PTEN/MMAC1 as a target in malignant melanoma and may provide an alternative means to localizing tumor suppressor genes.

Clinical efficacy of high-dose acyclovir in patients with human immunodeficiency virus infection: a meta-analysis of randomized individual patient data

A meta-analysis of 8 randomized trials (1792 patients, 2947 patient-years of follow-up) showed that acyclovir (> or = 3200 mg/day) offered a significant survival benefit (P = .006 by log-rank test) in human immunodeficiency virus (HIV) infection. The treatment effect did not vary significantly in patient subgroups of different CD4 cell counts, hemoglobin levels, age, race, and sex, and with or without AIDS diagnosis. Acyclovir treatment (hazard ratio, 0.78; 95% confidence interval [CI], 0.65-0.93), higher CD4 cell count (P < .001), higher hemoglobin level (P < .001), and younger age (P < .001) reduced the hazard of mortality. Acyclovir decreased herpes simplex virus infections (odds ratio [OR], 0.28; 95% CI, 0.21-0.37) and varicella-zoster virus infections (OR, 0.29; 95% CI, 0.13-0.63) but not cytomegalovirus disease or mortality from lymphoma or Kaposi's sarcoma. A survival advantage was seen specifically in studies with high incidence of clinical herpesvirus infections (> or = 25% per year). Given the wide confidence intervals, the small effect in low-risk patients, and recent changes in HIV therapeutics, the results should be interpreted cautiously, but the meta-analysis supports the importance of pathogenetic interactions between herpesviruses and HIV.

Long-term health and employment outcomes of occupational asthma and their determinants

Occupational asthma is common, yet little is known about long-term outcomes in the United States. A case series of 55 (of 72) occupational asthma patients were interviewed in follow-up 31 (+/- 15) months after removal from the cause to evaluate asthma severity and employment outcomes. Standard criteria were used to rate severity. At follow-up, 54 subjects (98%) had active asthma, of which 26 cases (47%) were "severe." Multivariate analysis showed increased risk of "severe" asthma for women (odds ratio [OR] = 13.8; 95% confidence interval [95% CI] = 1.3 to 151.7) and industrial sector workers (OR = 11.9; 95% CI = 1.3 to 109.8). Thirty-eight subjects (69%) were unemployed, risk being greater for those with "severe" asthma (OR = 20.9; 95% CI = 1.9 to 229.8) and for those without a college degree (OR = 7.3; 95% CI = 1.2 to 43.4). These results indicate that occupational asthma is disabling and probably irreversible for most patients referred to a specialty clinic, despite prolonged removal from causative agents. Women, industrial workers, and those with severe asthma or lack of a college degree appear to be at risk for worse outcomes. Greater efforts at primary and secondary prevention should lessen the burden of long-term illness and unemployment due to occupational asthma.

Minimal effects of acrylonitrile on pulmonary and hepatic cell injury enzymes in rats with induced cytochrome P450

Acrylonitrile (AN) has many industrial applications but is a known carcinogen in animals and a suspect human carcinogen. Its toxicity is generally associated with its bioactivation, the initial step of which is epoxidation by cytochrome P450. While the hepatotoxicity and pneumotoxicity of AN in naive rats is generally low, the purpose of this study was to investigate the pneumotoxicity and hepatotoxicity of AN in adult male Sprague-Dawley rats and evaluate interactions with agents that may alter its metabolism. Five agents, phenobarbital, beta-naphthoflavone, pyridine, ethanol, and acetone, were administered prior to AN as inducers of CYP2B, CYP1A, and CYP2E1. Pneumotoxicity was measured as increases in y-glutamyltranspeptidase (GGT) and lactate dehydrogenase (LDH) in bronchoalveolar lavage fluid (BALF). Hepatotoxicity was measured as increases in serum sorbitol dehydrogenase (SDH). AN (1 mmol/kg ip) had little effect on liver or lung, even when given following most of the inducing agents. AN (1.5 mmol/kg) caused an increase in GGT, but had little effect on SDH or LDH. Acetone plus AN caused an increase in mortality and some indication of pneumotoxicity, but lung and liver were histologically normal. Thus AN alone even at a high dose had no effect on the liver or lung and minimal effects following induction of cytochrome P450 by acetone.

Factors associated with fatalities and injuries from hot-air balloon crashes

CONTEXT

Despite the increased popularity of hot-air balloon flight, data on injuries and fatalities associated with hot-air balloon crashes are limited.

OBJECTIVE

To determine factors associated with injury and death in hot-air balloon crashes.

DESIGN

Retrospective review of data collected from reports and investigations by the Civil Aeronautics Board and the National Transportation Safety Board.

STUDY SUBJECTS

Individuals involved in US hot-air balloon crashes from 1964 to 1995.

MAIN OUTCOME MEASURES

Total number of crashes and factors associated with fatality or serious injury.

RESULTS

From 1964 to 1995, a total of 495 hot-air balloon crashes involving 1533 persons were reported and included 92 fatalities and 384 serious injuries. Pilot error or incapacitation was determined subjectively by crash investigators to contribute to 85.1% of the crashes. In univariate analysis, collision with the ground was the most significant predictor of a fatality or serious injury (P<.001), and power-line contact was the most significant predictor of fatality (P<.001). In multiple logistic regression, only the type of object struck by a balloon predicted a fatal crash or a fatality or serious injury.

CONCLUSIONS

Although a number of factors likely contribute to increased severity of hot-air balloon crashes, the object struck during a crash is most predictive of fatality or serious injury. Preventive efforts are needed to decrease future injuries.

Retrospective dosimetry related to chronic environmental exposure

Radioactive contamination of the environment occurred in the early fifties as a result of the releases from the Mayak plutonium production complex (Southern Urals, Russia). The releases of liquid wastes into the Techa river resulted in chronic exposure of 30,000 residents of the riverside communities. Since 1951 90Sr body burdens have been measured for over half of this cohort. This paper presents the analysis of data on 90Sr in humans and describes the reconstruction of internal doses for these people.

Neutron spectra in the atmosphere from interactions of primary cosmic rays

Spectra of neutrons from interactions of primary cosmic rays in the earth's atmosphere are calculated with the Monte Carlo model FLUKA for various depths down to sea level. We discuss the environmental models describing the primary cosmic ray spectrum and details of the calculations. Neutron energy spectra are presented for different depths in the atmosphere and for different geographical locations. By comparing results of calculations to measurements on neutron spectra it is shown that FLUKA may serve as an important tool for the estimation of the radiation environment in the atmosphere.

Strontium transfer from maternal skeleton to the fetus estimated on the basis of the Techa river data

Measurements of 90Sr in human bone of inhabitants of the Techa river region were started in 1951, and since 1974 the Techa river population has been studied with a whole-body counter. One of the dosimetric tasks that could be decided using data on 90Sr measurements is direct evaluation of strontium transfer to the fetus from the maternal skeleton. Six cases were selected for which 90Sr measurements were available both for stillborn infants and their mothers. The ratio of 90Sr concentrations in fetal bone to maternal bone for the year of pregnancy has been evaluated. Two clusters of values were found and the difference between clusters could be explained by age-dependent features of maternal bone formation and remodelling. When the mother's 90Sr intake occurred in the period of intensive compact bone growth, the transfer coefficient was very low (0.012-0.032). If 90Sr ingestion occurred during the woman's reproductive age, the transfer to fetus was equal to 0.21-0.26.

Induction of chromosomal damage in CHO-K1 cells and their repair-deficient mutant XRS5 by X-ray and particle irradiation

The cytogenetic effects of X-rays and Au ions were investigated in repair-proficient CHO-K1 cells and their radiosensitive mutant strain xrs5, which shows a defect in the rejoining of DNA double-strand breaks. Both cell lines were synchronized by mitotic shake off, irradiated in G1-phase with either 250 kV X-rays or 780 MeV/u Au ions (LET: 1150 keV/micrometer) and chromosome aberrations were analyzed in first post-irradiation metaphases. Isoeffective doses of X-rays for the induction of aberrant cells and aberrations per cell were about 14 times lower for xrs5 than for CHO-K1 cells. After high LET radiation the difference in the cytogenetic response of both cell lines was drastically diminished. Furthermore, the analysis of the aberration types induced by sparsely and densely ionizing radiation showed for both cell lines specific changes in the spectrum of aberration types as LET increases. The experimental results are discussed with respect to the different types of lesions induced by sparsely and densely ionizing radiation.