Cumulative exposure to dust and gases as determinants of lung function decline in tunnel construction workers

AIMS

To study the relation between lung function decrease and cumulative exposure to dust and gases in tunnel construction workers.

METHODS

A total of 651 male construction workers (drill and blast workers, tunnel concrete workers, shotcreting operators, and tunnel boring machine workers) were followed up by spirometric measurements in 1989-2002 for an average of six years. Outdoor concrete workers, foremen, and engineers served as a low exposed referent population.

RESULTS

The between worker component of variability was considerably reduced within the job groups compared to the whole population, suggesting that the workers within job groups had similar exposure levels. The annual decrease in FEV1 in low-exposed non-smoking workers was 21 ml and 24 ml in low-exposed ever smokers. The annual decrease in FEV1 in tunnel construction workers was 20-31 ml higher than the low exposed workers depending on job group for both non-smokers and ever smokers. After adjustment for age and observation time, cumulative exposure to nitrogen dioxide showed the strongest association with a decrease in FEV1 in both non-smokers, and ever smokers.

CONCLUSION

Cumulative exposure to nitrogen dioxide appeared to be a major risk factor for lung function decreases in these tunnel construction workers, although other agents may have contributed to the observed effect. Contact with blasting fumes should be avoided, diesel exhaust emissions should be reduced, and respiratory devices should be used to protect workers against dust and nitrogen dioxide exposure.

Dynamic model tracking design for low inertia, high speed permanent magnet ac motors

Permanent magnet ac (PMAC) motors have existed in various configurations for many years. The advent of rare-earth magnets and their associated highly elevated levels of magnetic flux makes the permanent magnet motor attractive for many high performance applications from computer disk drives to all electric racing cars. The use of batteries as a prime storage element carries a cost penalty in terms of the unladen weight of the vehicle. Minimizing this cost function requires the minimum electric motor size and weight to be specified, while still retaining acceptable levels of output torque. This tradeoff can be achieved by applying a technique known as flux weakening which will be investigated in this paper. The technique allows the speed range of a PMAC motor to be greatly increased, giving a constant power range of more than 4:1. A dynamic model reference controller is presented which has advantages in ease of implementation, and is particularly suited to dynamic low inertia applications such as clutchless gear changing in high performance electric vehicles. The benefits of this approach are to maximize the torque speed envelope of the motor, particularly advantageous when considering low inertia operation. The controller is examined experimentally, confirming the predicted performance.

Report from the Faculty of Family Planning and Reproductive Health Care AGM, May 2003: Medical termination of pregnancy in the late first trimester

In the UK, mifepristone and gemeprost are licensed for medical termination of pregnancy (TOP) in the first trimester up to 63 days' amenorrhoea. Current practice, however, is to use low-dose (200 mg) mifepristone and misoprostol. We report a large cohort study using these drugs for medical TOP in the first trimester after 63 days amenorrhoea. Of 415 patients undergoing the procedure, 392 (95%) aborted completely and 96% required only two doses of misoprostol. We conclude that the regime is effective with few complications, however certain safeguards may be necessary for its widespread introduction

Changes in circulating concentrations of inhibins A and pro-alpha C during first trimester medical termination of pregnancy

BACKGROUND

Both inhibin A and inhibin pro-alpha C are detectable in the circulation in increasing amounts during establishment of pregnancy. However, their origins and functions remain to be elucidated. We have studied levels of inhibin A and inhibin pro-alpha C in serum samples collected at various stages during medical termination of pregnancy with consecutive use of mifepristone and misoprostol.

METHODS

Samples were collected from three groups of patients at different weeks of gestation (group A: 6-7 weeks, n = 6; group B: 7-8 weeks, n = 6; group C: 8-9 weeks, n = 6) at the time of administration of oral mifepristone, 48 h later just before administration of vaginal misoprostol and again soon after expulsion of the products of conception. Plasma concentrations of inhibin A and pro-alpha C were assayed using specific and sensitive enzyme-linked immunosorbent assays. Results were correlated with concentrations of hCG and progesterone.

RESULTS

We observed a significant fall in plasma concentration of inhibin pro-alpha C following administration of mifepristone, which continued after administration of misoprostol. In contrast mifepristone had no effect on plasma levels of inhibin A, which fell steeply only after administration of misoprostol.

CONCLUSIONS

These results suggest dissociation between major sources of inhibin A and inhibin pro-alpha C in early pregnancy. Treatment with mifepristone, a competitive antagonist of the progesterone receptor, resulted in a significant and rapid fall in concentrations of inhibin pro-alpha C, identifying a link between production of pro-alpha C and luteal steroidogenesis. In contrast, concentrations of inhibin A did not fall after mifepristone, identifying a predominantly feto-placental origin in early human pregnancy.

UK laboratory intercomparison on internal dosimetry

A laboratory intercomparison for internal dose assessment from a variety of intake scenarios is described. This is the first UK intercomparison using the revised ICRP Human Respiratory Tract and biokinetic models. Four United Kingdom laboratories participated and six cases were assessed. Overall, the agreement in internal dose assessments between laboratories was considered satisfactory with 79% of the assessed committed effective doses, e(50), for cases within a band of +/- 40% of the median value. The range (highest/lowest) in e(50) estimated by the laboratories was smallest (1.2) for a case involving inhalation of 137Cs. The range was greatest (6.0) for a case involving a wound with, and possible inhalation of, 238Pu, 239Pu and 241Am; the variation between laboratories in assessment of intakes could not be considered to be satisfactory in this case. Judgements on the most appropriate data to use in estimating intakes, choice of parameter values for use with the ICRP models and allowing for the effects of treatment with DTPA were important sources of variability between laboratories.

Pharmacokinetics of recombinant factor IX after intravenous and subcutaneous administration in dogs and cynomolgus monkeys

Hemophilia B therapy requires intravenous (IV) infusions of large volumes of factor IX due to the low concentration of factor IX in concentrates (approximately 100 IU/mL). High concentration recombinant factor IX (rFIX) could be a significant advance since it would reduce the large volumes necessary for IV dosing and allow for low-volume subcutaneous (SC) administration. To evaluate high concentration factor IX, we produced formulations with either 2,000 or 4,000 IU/mL and studied the SC bioavailability in beagle dogs, cynomolgus monkeys and hemophilia B dogs along with efficacy in hemophilia B dogs. Beagle dog SC bioavailability was 86.4% using a 2000 IU/mL formulation and 77.0% using a 4000 IU/mL formulation. Monkey bioavailability of a 4000 IU/mL formulation of rFIX was 34.8%. A single SC administration of 200 IU/kg (4000 IU/mL) of rFIX to hemophilia B dogs, produced factor IX clotting activity above 5% for 5 days with a bioavailability of 48.6%. High concentration SC rFIX has an acceptable pharmacokinetic profile in monkeys and dogs, and produces a sustained FIX activity in hemophilic dogs.

Ruptured superior thyroid artery from central vein cannulation: treatment by coil embolization

Central vein cannulation is associated with several complications, some of which may be fatal. This case report describes a life-threatening complication after insertion of a central venous line. An obese female patient with end-stage renal failure due to nephrotic syndrome developed a huge neck swelling and sudden airway obstruction after attempted cannulation of the internal jugular vein for haemodialysis. Tracheal intubation was achieved using a gum-elastic bougie. Investigations revealed abnormal blood clotting. The coagulopathy was treated, but the neck swelling continued to increase in size. Carotid angiography showed a ruptured right superior thyroid artery. The haemorrhage was controlled by coil embolization of the artery. This case report demonstrates the usefulness of the gum-elastic bougie in the presence of a difficult airway and of interventional radiology in the management of vascular accidents.

Effects of blasting fumes on exposure and short-term lung function changes in tunnel construction workers

OBJECTIVES

This study attempts to determine the effects of exposure to blasting fumes and its influence on the lung function of tunnel workers.

METHODS

Two groups of tunnel workers, one using ammonium nitrate fuel oil (ANFO) as the explosive and the other using size-sensitized emulsion (SSE), with 24 workers per group, were compared with a reference group (N=34) with low exposure. Spirometry was used to determine lung function. Personal exposure to total and respirable dust, alpha-quartz, volatile organic compounds, oil mist and vapors, formaldehyde, nitrogen dioxide, and carbon monoxide was measured.

RESULTS

The ANFO workers were more exposed to all the agents than the reference group and more exposed than the SSE workers to all the agents except total dust and carbon monoxide. The SSE workers were significantly more exposed to total dust and alpha-quartz than the reference group. High peak exposures to nitrogen dioxide (up to 20 ppm) occurred for the ANFO workers in contrast to the SSE workers, whose exposure did not exceed 2 ppm. The lung function of the ANFO workers significantly decreased by 3% for forced vital capacity, 7% for forced expiratory volume in 1 second, and 8% for forced expiratory flow rate from 25% to 75% of the forced vital capacity over the 11-day period. The changes were reversible. There were no significant changes among the SSE workers and the outdoor workers. The ANFO workers had a significant decrease in FEV1.0 when compared with both the SSE and outdoor workers.

CONCLUSIONS

Tunnel workers using ANFO explosive show a temporary reduction in lung function, whereas those using SSE do not. The most likely explanation for the observed changes is peak exposures to nitrogen dioxide.

Dust and gas exposure in tunnel construction work

Personal exposures to dust and gases were measured among 189 underground construction workers who were divided into seven occupational groups performing similar tasks in similar working conditions: drill and blast crew; shaft-drilling crew; tunnel-boring machine crew; shotcreting operators; support workers; concrete workers; and electricians. Outdoor tunnel workers were included as a low-exposed reference group. The highest geometric mean (GM) exposures to total dust (6-7 mg/m3) and respirable dust (2-3 mg/m3) were found for the shotcreters, shaft drillers, and tunnel-boring machine workers. Shaft drillers and tunnel-boring machine workers also had the highest GM exposures to respirable alpha-quartz (0.3-0.4 mg/m3), which exceeded the Norwegian occupational exposure limit (OEL) of 0.1 mg/m3. Shaft drillers had the highest exposure to oil mists (GM=1.4 mg/m3), which was generated mainly from pneumatic drilling. For other groups, exposure to oil mist from diesel exhaust and spraying of oil onto concrete forms resulted in exposures of 0.1-0.5 mg/m3. Exposure to nitrogen dioxide was similar across all groups (GM=0.4-0.9 ppm), except for shaft drillers and tunnel-boring machine workers, who had lower exposures. High short-term exposures (>10 ppm), however, occurred when workers were passing through the blasting cloud.

Dissociation of infectivity and pathogenicity in Borrelia burgdorferi

Clonal Borrelia burgdorferi N40 (cN40) passaged 75 times in vitro (N40-75) infects mice but does not cause disease. N40-75 passaged 45 times further in vitro (N40-120) was no longer infectious and lacked genes encoded on linear plasmids 38 and 28-1, among other differences. These data suggest that B. burgdorferi cN40, N40-75, and N40-120 have distinct phenotypes that can be used to dissect the genetic elements responsible for pathogenicity and infectivity.

Isoenzyme multiplicity and characterization of recombinant manganese peroxidases from Ceriporiopsis subvermispora and Phanerochaete chrysosporium

We expressed cDNAs coding for manganese peroxidases (MnPs) from the basidiomycetes Ceriporiopsis subvermispora (MnP1) and Phanerochaete chrysosporium (H4) under control of the alpha-amylase promoter from Aspergillus oryzae in Aspergillus nidulans. The recombinant proteins (rMnP1 and rH4) were expressed at similar levels and had molecular masses, both before and after deglycosylation, that were the same as those described for the MnPs isolated from the corresponding parental strains. Isoelectric focusing (IEF) analysis of rH4 revealed several isoforms with pIs between 4.83 and 4.06, and one of these pIs coincided with the pI described for H4 isolated from P. chrysosporium (pI 4.6). IEF of rMnP1 resolved four isoenzymes with pIs between 3.45 and 3.15, and the pattern closely resembled the pattern observed with MnPs isolated from C. subvermispora grown in solid-state cultures. We compared the abilities of recombinant MnPs to use various substrates and found that rH4 could oxidize o-dianisidine and p-anisidine without externally added manganese, a property not previously reported for this MnP isoenzyme from P. chrysosporium.

A novel mutation in a family with non-erythroid variant form of acute intermittent porphyria

Acute intermittent porphyria (AIP), an autosomal dominant disorder, is divided into two forms, the classical form (more than 95%) and the non-erythroid variant form, according to erythroid porphobilinogen deaminase (PBGD) activity. In the variant form, the PBGD activity is essentially normal. Detection of presymptomatic mutation carriers relies on a DNA test. This variant form of AIP is very rare, with only nine families carrying five different mutations reported in the literature. Here we report a novel G-to-T transversion in the first position of intron 1 of the PBGD gene in a family with this variant form of AIP. We also review all previously reported cases and propose an effective diagnostic approach.

The value of a screen and treat policy for Chlamydia trachomatis in women attending for termination of pregnancy

We aimed to assess the efficacy of a screen and treat policy for sexually transmitted infections in women requesting termination of pregnancy, with particular reference to Chlamydia trachomatis. A retrospective review of 100 consecutive cases of Chlamydia-positive women between December 1995 and February 1998, was performed. The referral rate to genitourinary medicine (GUM), the subsequent management, contact tracing and treatment of partners were assessed. Ninety-nine women were referred to the GUM department, of whom 72 (71.4%) attended. Eighteen (25%) required further treatment. Seventy-five women identified 89 potentially infected men, of whom 62 (69%) attended for treatment. Identification of positive cases with referral to GUM enabled tests of cure to be carried out, treatment of those reinfected and re-enforcement of behaviour modification, in addition to successful contact tracing. This policy may confer greater benefit for the patient herself and make a significant impact on the reservoir of infection in the community when compared to a policy of blanket prophylactic antibiotic treatment at the time of termination. The implications for future service provision are discussed.

Termination of pregnancy: patients' perceptions of care

BACKGROUND

Little is known about women's perceptions of care in termination of pregnancy (TOP). Developing an understanding of how care is experienced is crucial to improvements in services.

METHOD

Two hundred and eight women undergoing either a medical or surgical TOP reported on their perspectives of the experience and the care received. A mix of questionnaire and open questions analysed by content analysis was used. Women reported on the aspects which were most stressful, helped them to feel more relaxed, were unexpected in some way, and also on the provision of information and on the quality of staff care.

RESULTS

The most stressful aspects for the medical group related to the physical and emotional aspects of the process, whilst for the surgical group it concerned waiting in hospital for the operation. Whilst little was unexpected for the surgical group, many aspects came as a surprise to the medical group. Seeing the foetus was particularly difficult. All information provided was viewed as helpful, with greater information required about the phase following termination. Care from staff was rated positively, although areas for improvement in terms of opportunity to ask questions and ensuring concerns were dealt with were identified. Caring and non-judgemental staff attitudes were viewed as particularly important in helping women to feel as relaxed as possible in a potentially stressful situation.

CONCLUSION

Surgical termination schedules should avoid a long waiting time once the woman has been admitted. More adequate preparation is required for those having medical termination so that they have realistic expectations of what will happen, including the possibility of seeing the foetus. More attention to information about the time following termination, including possible emotional responses, is needed. The importance of positive staff attitudes in the quality of care is emphasised.

Household solvent exposures and childhood acute lymphoblastic leukemia

OBJECTIVES

This study explored the risk of childhood acute lymphoblastic leukemia (ALL) associated with participation by household members in hobbies or other home projects involving organic solvents.

METHODS

Participants in this case-control study were 640 subjects with ALL and 640 matched controls.

RESULTS

Childhood ALL was associated with frequent (> 4 times/month) exposure to model building (odds ratio [OR] = 1.9; 95% confidence interval [95% CI] = 0.7, 5.8) and artwork using solvents (OR = 4.1; 95% CI = 1.1, 15.1). We also found elevated risk (OR = 1.7; 95% CI = 1.1, 2.7) among children whose mothers lived in homes painted extensively (> 4 rooms) in the year before the children's birth.

CONCLUSIONS

In this exploratory study, substantial participation by household members in some common household activities that involve organic solvents was associated with elevated risks of childhood ALL.

Tick bite and Lyme borreliosis risk at a recreational site in England

The risk of tick bite and Lyme borreliosis in a forested area in England with public access was studied over a two-year period. Tick infestation levels were high with more than 1000 members of the public reporting for tick removal at a local clinic. Most of the attached ticks were nymphs (82%) and distinct differences in anatomical sites of attachment were observed in children and adults. Children sustained nymphal bites to the head, neck and axilla region much more frequently than adults (48 vs. 10%), whereas adults were bitten on the lower legs more frequently than children (46 vs. 9%). The vegetation was heavily infested with ticks and high numbers were particularly associated with areas used by deer. The average density of nymphs collected from the vegetation was 14.1 per 10 m2 (range 5.1-43.6). Infection rates of these nymphs determined by PCR and indirect IFA ranged from 5.2-17.0%, and the genospecies Borrelia valaisiana and B. garinii were detected, suggesting that birds may be important reservoir hosts in this area. It is estimated that, at the level of tick challenge observed here, at least 50 persons per year may be bitten by infected ticks at this site. However, no cases of Lyme borreliosis have been reported through the clinic follow-up procedure, and sera from 19 forest workers were negative for antibody to B. burgdorferi sensu lato. Despite the high challenge from tick bites, this particular recreational forest site poses a low risk of infection to the general public, and prophylactic antibiotic treatment or serological testing following a bite is not justified.

The sequence of the preparative procedures affects the success of cryostorage of cassava somatic embryos

Cassava primary somatic embryos were prepared for cryostorage using both physical drying and cryoprotectant application stages. The effects of the sequence by which these preparative events were applied to the material was investigated. The drying of the somatic embryos before the application of the cryoprotectants resulted in a significantly higher viability after cryostorage than when the material was first exposed to the cryoprotectants and then dried. The impact of these preparative procedures on sub-cellular detail was monitored by means of transmission electron microscopy.