Respiratory symptoms in insect breeders.

BACKGROUND: A number of specialist food suppliers in the UK breed and distribute insects and insect larvae as food for exotic pets, such as reptiles, amphibians and invertebrates. AIMS: To investigate the extent of work-related (WR) symptoms and workplace-specific serum IgE in workers potentially exposed to a variety of biological contaminants, including insect and insect larvae allergens, endotoxin and cereal allergens at a UK specialist insect breeding facility. METHODS: We undertook a study of respiratory symptoms and exposures at the facility, with subsequent detailed clinical assessment of one worker. All 32 workers were assessed clinically using a respiratory questionnaire and lung function. Eighteen workers consented to provide serum for determination of specific IgE to workplace allergens. RESULTS: Thirty-four per cent (11/32) of insect workers reported WR respiratory symptoms. Sensitization, as judged by specific IgE, was found in 29% (4/14) of currently exposed workers. Total inhalable dust levels ranged from 1.2 to 17.9 mg/m(3) [mean 4.3 mg/m(3) (SD 4.4 mg/m(3)), median 2.0 mg/m(3)] and endotoxin levels of up to 29435 EU/m(3) were recorded. CONCLUSIONS: Exposure to organic dusts below the levels for which there are UK workplace exposure limits can result in respiratory symptoms and sensitization. The results should alert those responsible for the health of similarly exposed workers to the potential for respiratory ill-health and the need to provide a suitable health surveillance programme.

Borna disease virus and mental health: a cross-sectional study.

BACKGROUND: Borna disease is an infectious neurological disease of horses, sheep and possibly other animals. A role for Borna disease virus (BDV) in human neurological and psychiatric illness has been proposed, but this hypothesis remains controversial. AIM: To investigate the epidemiology of BDV in UK farming communities. DESIGN: Retrospective cohort study. METHODS: We measured the seroprevalence of BDV in the PHLS Farm Cohort, a representative sample of those employed in agriculture in the UK, and investigated the clinical significance of our findings by comparing the prevalence of symptoms of neurotic psychopathology in those found seropositive and seronegative. RESULTS: Seroprevalence was 2.3% (95%CI 1.3- 4.0%) in 1994, 3.1% in 1996 (95%CI 1.9-5.0%) and 2.6% in 1999 (95%CI 1.5%-4.6%). Those living or working on livestock farms had higher seroprevalence (2.6%) than those on mixed (2.3%) or arable (1.6%) farms, but this was not statistically significant. Exposure to horses, sheep and cats did not increase risk of seropositivity. Seropositives were no more likely to report symptoms of psychiatric morbidity. DISCUSSION: UK farming populations appear to be exposed to Borna disease virus. However, we found no evidence that exposure to BDV was associated with morbidity in this healthy occupational cohort.

Occupational exposure to metalworking fluid mist and sump fluid contaminants.

This paper summarizes the analytical and occupational hygiene findings from a recent survey of occupational exposure to metalworking fluids (MWFs) in the engineering industry. The aim of the survey was to link MWF mist exposure measurements with particular engineering processes and controls, and utilize the data obtained to develop exposure standards. At the same time the opportunity was taken to assess fluid management and control, including bacterial and fines contamination in the machine sumps. In general, occupational exposure to mineral oil MWF mist was controlled to <3 mg/m(3) (8 h time-weighted average) and to <1 mg/m(3) for water-mix MWF mist (in terms of the concentrate). These exposure values do not necessarily represent best practice, but are believed to be achievable and representative of industry as a whole. Gravimetric analysis of the total inhalable particulate was found to be a good predictor of mineral oil MWF mist but not for water-mix MWF mist. Grinding and drilling operations produced higher exposures than turning and milling for water-mix fluids. There were insufficient data to compare machining operations for mineral oil MWFs. On the whole, fluid management was found to be poor, with most sites failing to meet industry good practice or Health & Safety Executive (HSE) standards. Some of the operating procedures utilized were deficient or unsatisfactory. Poor standards of fluid management were found at all sizes of company. High levels of bacteria, endotoxin and fines were found in sumps, and control of other factors, such as water-mix fluid concentration, was often poor. Mineral oils had higher levels of fines than water-mix fluids (medians of 395 and 18 mg/l, respectively), and grinding produced high levels of fines in both types of MWF. Many water-mix sumps contained bacterial levels of >1 x 10(6) CFU/ml, and endotoxin levels of >100 000 EU/ml were not uncommon. The median values were 109 000 CFU/ml and 8039 EU/ml, respectively. Mists could potentially contain extensive contamination from bacteria and endotoxin. Analysis of the data suggests that sumps operating under typical conditions for machining (a temperature of 20 degrees C, a pH of 9 and a fluid strength below 10%), also appear to provide optimum conditions for the proliferation of bacteria. Low levels of benzo[a]pyrene (median 0.03 micro g/g) were found in the mineral oils, and low levels of N-nitrosodiethanolamine (median 0.4 micro g/ml) were found in the water-mix MWFs. The results of this work will contribute to guidance from the HSE, setting out accepted industry good practice, including guide values for MWF mist and sump fluid contaminants, with significant emphasis on sump fluid management (maintenance and monitoring), as well as control issues.

Two phases of increased cell death in the inner retina following early elimination of the ganglion cell population.

Neurons in the inner nuclear layer (INL) of the vertebrate retina undergo considerable programmed cell death during development, but the determinants of this cell death remain largely unknown. The present study examines the role of retinal ganglion cells in support of INL neurons in the developing ferret retina. The retinal ganglion cell population was eliminated by optic nerve transection at postnatal day (P) 2, and the incidence of cell death was examined using terminal deoxytransferase dUTP nick-end labelling (TUNEL) at various ages during the first 3 postnatal weeks. Significant increases in TUNEL-positive cells were observed in the neuroblast layer (NBL) as early as P3, prior to synapse formation within the inner plexiform layer (IPL), and again in the INL at P22, the normal peak of naturally occurring cell death within the ferret's INL. A decrease in TUNEL-positive cells was found in the NBL at P8. These results show three phases of response to the loss of retinal ganglion cells and suggest that cells in the NBL/INL are normally dependent on retinal ganglion cells for their survival. Recent studies have shown that certain populations of retinal neurons are reduced in adult animals that had lost the population of ganglion cells during early development, so the present study also examined when this reduction could first be detected. The number of parvalbumin-immunoreactive amacrine cells was decreased significantly in the NBL of the manipulated eye as early as P8, when we could first label this population, and this difference persisted through adulthood. The fact that cell death in the NBL has already increased within 24 hours of ganglion cell elimination, coupled with the specificity of this effect on the adult complement of INL cell types, shows that cell-cell interactions controlling survival are already highly specific for particular types of retinal neuron early in development

Structural studies of the tRNA domain of tmRNA.

tmRNA is a small, stable prokaryotic RNA. It rescues ribosomes that have become stalled during the translation of mRNA fragments lacking stop codons, or during periods of tRNA scarcity. It derives its name from the presence of two separate domains, one that functions as a tRNA, and another that serves as an mRNA. We have carried out modeling and transient electric birefringence studies to determine the angle between the acceptor stem and anticodon stem of the tRNA domain of Eschericia coli tmRNA. The results of the modeling studies yielded an interstem angle of 110 degrees, in agreement with the lower end of the range of angles (111 degrees -137 degrees ) determined experimentally for various solution conditions. The range of experimental angles is greater than the angles observed for any of the tRNA crystal structures, in line with the presence of a shortened D stem. The secondary structure of the tRNA domain is conserved for all known tmRNA sequences, so we propose that the angle is also conserved. These results also suggest that the region of tmRNA between P2a and P2b may interact with the decoding site of the ribosome.

RNA scaffolds for minihelix-based aminoacyl transfer: design of "transpeptizymes".

Abstract Some evidence and considerations suggest that RNA minihelices based on the acceptor-TΨC stem-loop of tRNAs are the historical, more ancient part of the tRNA structure. These minihelices are substrates for aminoacylation by tRNA synthetases. In the transition from the RNA world to the theatre of proteins, aminoacyl minihelices may have had a role in early systems of peptide synthesis. Such systems would require bringing together aminoacyl groups into close proximity in order for peptide bonds to form. Here we report the design of RNA scaffolds based on pieces of the structure of the P4-P6 domain of the Tetrahymena ribozyme. RNA minihelices were incorporated into these scaffolds and the resulting RNAs could be enzymatically aminoacylated. The RNA scaffolds containing the minihelix-like pieces associated spontaneously to create the presumptive P4-P6 structure and thereby bring together the substrates for aminoacylation. Thus, peptide synthesis with associating RNA scaffolds that contain minihelix-like motifs appears plausible.

The adaptation of existing personal inhalable aerosol samplers for bioaerosol sampling.

Health-related monitoring of bioaerosol exposures in the workplace should ideally be carried out using size-selective personal samplers that separate the aerosol into biologically relevant size fractions and allow both quantification and identification of the microorganisms present in each fraction. As a first stage in the development of personal bioaerosol samplers a number of collection substrates were assessed for their ability to maintain the viability of the collected microorganisms, so that subsequent culturing and species identification may be carried out. The substrates were tested with bioaerosols of varying robustness, consisting of Saccharomyces cerevisiae cells, Escherichia coli cells, and Penicillium expansum spores, aerosolized under controlled environmental conditions. The survival of microorganisms on each test substrate, assessed on the basis of the culturable fractions of cells recovered, was compared with that of microorganisms collected in a reference glass cyclone sampler. These bioefficiency tests identified the substrate combinations with the potential to fulfill personal sampler design criteria. The substrates were then subjected to further development to evaluate and optimize their particle size selection characteristics. The outcome of this work is two prototype personal bioaerosol samplers in which size-selective substrates are adapted for use in existing designs of personal inhalable sampler. This offers an effective and low-cost solution to personal monitoring of bioaerosol exposures in the workplace.

Mapping of the target antigens of the rotavirus-specific cytotoxic T cell response.

The cytotoxic T cell (CTL) response in C57/B16 (H-2b) mice to rotavirus has been analysed using a cognate set of vaccinia virus recombinants covering the 12 primary gene products of the UKtc strain of bovine rotavirus. The gene products of RNA segments 5 (VP5/NSP-1) and 8 (VP7) both elicited a classic CD8+ Class I MHC restricted CTL response. Using L cells transfected with specific Class I MHC loci as targets the VP5/NSP-1 response was found to be restricted at Db and the VP7 response at Kb. Vaccinia virus recombinants expressing VP7 genes from seven G serotypes were used to show that the CTL response to this antigen is completely cross-reactive. By contrast, using the same strategy the CTL response to VP5/NSP-1 was found to be virus strain specific. A vaccinia virus recombinant carrying RNA segment 5 from the deletion mutant P9D delta 5 was used to localize at least one CTL epitope in VP5/ NSP-1 to the first 150 amino acids of the protein. The expression of a number of fragments of VP7 in vaccinia virus recombinants was used to show that the CTL epitope (amino acids 31-40) previously identified through the use of synthetic peptides is virus serotype specific rather than cross-reactive.

Management of the coronary-subclavian steal syndrome with balloon angioplasty. A case report and review of the literature.

A fifty-two-year-old woman with angina pectoris due to coronary-subclavian steal syndrome through a left internal mammary artery graft placed distal to a left anterior descending artery stenosis is presented. Retrograde flow through the mammary artery graft due to severe left subclavian stenosis was observed angiographically. Accordingly, left subclavian balloon angioplasty was performed, restoring normal antegrade flow through the internal mammary artery graft and resulting in resolution of the patient's symptoms. The patient was subsequently discharged with no evidence of angina. Carotid-subclavian bypass surgery was avoided, reducing patient discomfort, procedural risk, and expense.

Is silent ischemia on the routine admission ECG an important finding?

The authors' objective was to determine if, in the absence of known coronary artery disease, ST-T changes suggestive of silent ischemia on the admission electrocardiogram (ECG) identify a group of patients at high risk for cardiac event or death. A prospective cohort study was undertaken at the university hospital of a tertiary care center. All patients admitted to the hospital during the 5-month study period were screened. The authors found 54 patients with risk factors but no symptoms of coronary artery disease whose admission ECGs showed silent ischemia (ischemia group), and 71 patients with similar risk of coronary artery disease but without admission ECGs showing silent ischemia (control group). Three-week and 6-month incidences of angina, myocardial infarction, and death among patients in the silent ischemia and control groups were compared. Seven (13%) patients in the silent ischemia group had cardiac events or noncardiac death in the subsequent 3 weeks versus one (1%) noncardiac death in the control group (p < 0.02). At 6 months, eight (15%) patients in the silent ischemia group versus two (3%) in the control group had cardiac events (p = 0.02). It is concluded that among patients with risk factors but no symptoms of coronary artery disease, silent ischemia on the admission ECG is associated with an increased likelihood of short-term death or cardiac event.

Episodic coma due to acute basilar artery migraine: correlation of EEG and brainstem auditory evoked potential patterns.

Our patient presented with three episodes of deep coma in 5 weeks, followed by a complete recovery. The neuroradiological tests and spinal fluid analysis excluded structural lesions, including subarachnoid hemorrhage, from the diagnosis. A nonconvulsive status was excluded by 24-hour EEG monitoring. The EEGs and brainstem auditory evoked responses were abnormal during ictus, but they reversed to normal with the clinical recovery. Timely neurophysiological tests helped in the diagnosis of basilar artery migraine.

Coronary stents: a review of recent developments.

Coronary stent placement is one of the newest treatments for occlusion of the coronary arteries. This technique has the potential to minimize restenosis and reduce or eliminate abrupt closure, common complications of percutaneous transluminal coronary angioplasty (PTCA). Initial studies in Europe in the mid-1980s indicated a problem with restenosis due to thrombosis and intimal hyperplasia in stented arteries. Recent investigational studies of the Palmaz balloon-expandable stent in the United States, however, show great promise in solving those problems. It is hoped that coronary stenting may be used for lesions now treated by coronary artery bypass graft surgery, as well as for improving the outcome of PTCA.