Long distance directional growth of dopaminergic axons along pathways of netrin-1 and GDNF

Different experimental and clinical strategies have been used to promote survival of transplanted embryonic ventral mesencephalic (VM) neurons. However, few studies have focused on the long-distance growth of dopaminergic axons from VM transplants. The aim of this study is to identify some of the growth and guidance factors that support directed long-distance growth of dopaminergic axons from VM transplants. Lentivirus encoding either glial cell line-derived neurotrophic factor (GDNF) or netrin-1, or a combination of lenti-GDNF with either lenti-GDNF family receptor α1 (GFRα-1) or lenti-netrin-1 was injected to form a gradient along the corpus callosum. Two weeks later, a piece of embryonic day 14 VM tissue was transplanted into the corpus callosum adjacent to the low end of the gradient. Results showed that tyrosine hydroxylase (TH(+)) axons grew a very short distance from the VM transplants in control groups, with few axons reaching the midline. In GDNF or netrin-1 expressing groups, more TH(+) axons grew out of transplants and reached the midline. Pathways co-expressing GDNF with either GFRα-1 or netrin-1 showed significantly increased axonal outgrowth. Interestingly, only the GDNF/netrin-1 combination resulted in the majority of axons reaching the distal target (80%), whereas along the GDNF/GFRα-1 pathway only 20% of the axons leaving the transplant reached the distal target. This technique of long-distance axon guidance may prove to be a useful strategy in reconstructing damaged neuronal circuits, such as the nigrostriatal pathway in Parkinson's disease.

Transgene expression in the striatum following intracerebral injections of DNA nanoparticles encoding for human glial cell line-derived neurotrophic factor

A goal of our studies is to develop a potential therapeutic for Parkinson's disease (PD) by a human glial cell line-derived neurotrophic factor (hGDNF) expression plasmid administered to the rat striatum as a compacted DNA nanoparticle (DNP) and which will generate long-term hGDNF expression at biologically active levels. In the present study, we used a DNA plasmid encoding for hGDNF and a polyubiquitin C (UbC) promoter that was previously shown to have activity in both neurons and glia, but primarily in glia. A two-fold improvement was observed at the highest plasmid dose when using hGDNF DNA incorporating sequences found in RNA splice variant 1 compared with splice variant 2; of note, the splice variant 2 sequence is used in most preclinical studies. This optimized expression cassette design includes flanking scaffold matrix attachment elements (S/MARs) as well as a CpG-depleted prokaryotic domain and, where possible, eukaryotic elements. Stable long-term GDNF activity at levels 300-400% higher than baseline was observed following a single intracerebral injection. In a previous study, DNP plasmids encoding for reporter genes had been successful in generating long-term reporter transgene activity in the striatum (>365 days) and in this study produced sustained GDNF activity at the longest assessed time point (6 months).

Atrioventricular valvular angiectasis in Sprague-Dawley rats

Subendothelial heart valve angiectasis has been reported in cows, dogs, pigs, rats, mice, and in human fetuses and newborns. We observed a high incidence (62 in 208 animals examined) of spontaneous angiectasis on the atrioventricular (AV) valves in 10- to 40-week-old Sprague-Dawley rats. The angiectasis was observed predominately on the septal cusp of the right AV valve and located near the AV ostium in 57 of 62 animals. Of the remaining 5 valvular angiectases, 2 were present on the parietal cusp of the right AV valve and 3 were on the left AV valve. The angiectases were single or multiple, ranging from 40 to 300 microm in diameter and were characterized by light microscopy as blood-filled dilatations lined by endothelium. Spontaneously occurring abnormalities in normal laboratory animals, such as the spontaneous valvular angiectasis reported here, need to be differentiated from drug-related lesions.

Downscatter correction and choice of collimator in 123I imaging

(123)I imaging is increasingly used in nuclear medicine but downscatter from high (>300 keV) energy emissions degrades the image and introduces variation in sensitivity with depth when imaging with a low energy collimator. A dual windowing technique using a matched window immediately above the principle window to correct for the effects of downscatter is described. The technique is shown to correct for the variation in sensitivity with depth and to reduce outlying scatter. Quantitative imaging of (123)I using a low energy collimator should always employ downscatter correction.

Predictors of early leaving from the cotton spinning mill environment in newly hired workers

OBJECTIVE

This longitudinal study aimed to identify the predictors of leaving during the first year of employment from the cotton spinning mill environment in newly hired workers.

METHODS

One hundred and ninety eight consecutively appointed new employees were investigated by questionnaire, lung function test, and skin test. They were examined before employment and at the end of the 1st week, and the 1st, 3rd, 6th, and 12th month after starting work and when possible before leaving their job. 572 personal dust sampling and 191 endotoxin measurements were performed to assess the environmental exposure. For the univariate analysis chi2, Student t tests, ANOVA, and Kruskall Wallis tests were used. Cox proportional hazards analysis was used to identify factors associated with leaving the job.

RESULTS

Fifty three per cent of workers left the mill environment during their first working year. Work related lower respiratory tract symptoms reported at the third month were associated with an increase rate of leaving the industry compared to those remaining in the industry (25% v 4.8%; p<0.005). Having respiratory symptoms at the first month of work predicted those leaving the industry at some point in the next 11 months. According to the Cox model, increasing age and having work related lower respiratory tract symptoms were found to be predictors for leaving job at the first working year. Atopic status, dust and endotoxin levels, and lung function changes were not consistently predictive of workers who left the industry in the follow up period.

CONCLUSION

This study demonstrated that work related respiratory symptoms can predict workers likely to leave the cotton mill environment during the first year of employment, but atopy or acute lung function changes do not.

Endotoxin exposure in asthmatic children and matched healthy controls: results of IPEADAM study

Children spend increasing time indoors. Exposure to environmental factors may contribute to the development or exacerbation of the asthmatic phenotype. Inter-relationships between these factors might influence the manifestation of asthma. Endotoxin exposure has been shown to have pro-inflammatory and protective effects in different situations. We investigated the exposure to several indoor pollutants (endotoxin, Der p 1, damp, ETS, PM2.5) in asthmatic and healthy children. The children were recruited from two primary care centers according to their response to a validated questionnaire. Asthmatic children were matched for sex, age and sib-ship size with children living in asthma free households. Of 90 matched pairs, higher levels of endotoxin were found in the living room carpets, but not the bedroom carpet or mattresses of the asthma compared with the control homes (STATA analysis OR: 1.88 (1.11-3.18); P=0.018). Asthmatic children were also more likely to live as part of a single parent family, in a house where the parents self-reported the presence of damp, and where the living room had been redecorated in the 12 months prior to the sampling visits. This study suggests that endotoxin in urban homes is a risk factor for the development of asthma. Moreover, this study found that there were no statistically significant interactions between environmental factors.

PRACTICAL IMPLICATIONS

This study has demonstrated that the home environments of English children (4-17) with asthma and without the disease do not differ greatly. With the exception of endotoxin, the parameters examined in this study, including house dust mite allergens, nitrogen dioxide, ETS and damp are unlikely to be related to the development of asthma. Avoidance of these pollutants may not be beneficial in preventing asthma in this age group.

Multiphonon vibrations at high angular momentum in 182 Os

Evidence is presented for multiphonon excitations based on a high-spin (25 Planck) intrinsic state in the deformed nucleus 182 Os. Angular momentum generation by this mode competes with collective rotation. The experimental data are compared with tilted-axis cranking calculations, supporting the vibrational interpretation. However, the lower experimental energies provide evidence that more complex interactions of states are playing a role.

Monocyte CD14 response following endotoxin exposure in cotton spinners and office workers

BACKGROUND

Monocyte cell surface CD14 acts as the major lipopolysaccharide (LPS) binding structure, and as such is of interest in the etiology of LPS induced disease.

METHODS

The objective was to assess change in monocyte cell surface CD14 and CD4+ CD25+ lymphocytes in a group of cotton workers exposed to LPS over a working week, and to compare this to changes in office workers. Twenty-five cotton workers and nine office workers were studied. Monocyte CD14 fluorescence was measured by flow cytometry, on samples taken pre-shift on a Monday morning (baseline/pre-exposure), and subsequently after 6 and 72 hr. The majority of cotton workers were exposed to at least 1 EU/m(3) of endotoxin over a working shift, and some highly exposed (between 100 and 400 EU/m(3)).

RESULTS

After 6 hr of work in the mill, cotton workers developed a significant upregulation in CD14 in comparison to office workers (P = 0.016), whereas CD14 expression had returned to levels not significantly differing from the office workers at 72 hr after first work exposure (P = 0.426).

CONCLUSIONS

We propose that CD14 expression on monocytes may help to determine the mechanism of action of lipopolysaccharide in producing respiratory ill health, and may ultimately play a role in monitoring the health effect associated with LPS exposure in the workplace.

An ex vivo angiogenesis assay utilizing commercial porcine carotid artery: modification of the rat aortic ring assay

The study of angiogenesis as a therapeutic target requires a reliable, physiologically relevant, and technically straightforward assay. An ex vivo assay bridges the gap between cell-based assays, which may not realistically represent the complex process of vessel sprouting, and in vivo assays, which are time consuming and expensive. Porcine carotid arteries provide an ideal tissue source for angiogenesis inhibitor screens due to their availability, physiological relevance and large size. 1.5 mm2 fragments of porcine carotid arteries were incubated in 48-well culture plates and sandwiched between two 100 microliters layers of Matrigel. Sprouting was observed from the explants and quantitated, using a digital imaging system, after two weeks of incubation. Histological analysis using Factor VIII-related antigen (von Willebrand Factor) as an endothelial cell-specific marker identified these sprouts, which were consistent with endothelial cell morphology, supporting the system as a model of angiogenesis. Accordingly, the angiogenesis inhibitors suramin, 2-methoxyestradiol, and the matrix metalloprotease inhibitor Batimastat were shown to completely inhibit sprouting at 50, 0.5, and 5.0 micrograms/ml, respectively and to have ED50 values of 23, 0.15, and 0.14 microgram/ml. This assay shows good reproducibility and eliminates animal to animal variation. The system should prove adaptable to other forms of angiogenic stimulation, ultimately making a variety of assays for angiogenesis available to laboratories of limited resources.

Loss of presenilin 1 is associated with enhanced beta-catenin signaling and skin tumorigenesis

Presenilin 1 (PS1) is required for the proteolytic processing of Notch and the beta-amyloid precursor protein (APP), molecules that play pivotal roles in cell-fate determination during development and Alzheimer's disease pathogenesis, respectively. In addition, PS1 interacts with beta-catenin and promotes its turnover through independent mechanisms. Consistent with this activity, we report here that PS1 is important in controlling epidermal cell proliferation in vivo. PS1 knockout mice that are rescued through neuronal expression of human PS1 transgene develop spontaneous skin cancers. PS1-null keratinocytes exhibit higher cytosolic beta-catenin and beta-catenin/lymphoid enhancer factor-1/T cell factor (beta-catenin/LEF)-mediated signaling. This effect can be reversed by reintroducing wild-type PS1, but not a PS1 mutant active in Notch processing but defective in beta-catenin binding. Nuclear beta-catenin protein can be detected in tumors. Elevated beta-catenin/LEF signaling is correlated with activation of its downstream target cyclin D1 and accelerated entry from G(1) into S phase of the cell cycle. This report demonstrates a function of PS1 in adult tissues, and our analysis suggests that deregulation of beta-catenin pathway contributes to the skin tumor phenotype.

Alteration of Cx43:Cx40 expression ratio in A7r5 cells

Connexins (Cx) 40 and 43 are coexpressed by several cell types at ratios that vary as a function of development, aging, and disease. Because these connexins form heteromeric channels, changes in expression ratio might be expected to significantly alter the connexin composition of the gap junction channel population and, therefore, gap junction function. To examine this possibility, we stably transfected A7r5 cells, which naturally coexpress Cx43 and Cx40, with a vector encoding antisense Cx43. Cx43 mRNA continued to be expressed in the antisense transfected clones, although levels were inversely related to the number of copies of antisense DNA incorporated into the genome. Protein levels, quantified in the clones with the highest and lowest Cx43:Cx40 mRNA ratios, were not well predicted by the mRNA levels, although the trends predicted by the Cx43:Cx40 mRNA ratio were preserved. Electrical coupling did not differ significantly between clones, but the clone with elevated Cx43:Cx40 protein expression ratio and unchanged Cx43 banding pattern was significantly better dye coupled than the parental A7r5 cells. These results suggest that as the Cx43:Cx40 ratio increases, provided alterations of Cx43 banding pattern (phosphorylation) have not occurred, permeability to large molecules increases even though electrical coupling remains nearly constant.

Survey of symptoms, respiratory function, and immunology and their relation to glutaraldehyde and other occupational exposures among endoscopy nursing staff

OBJECTIVES

To find the nature and incidence of symptoms experienced by a large sample of hospital endoscopy nurses. To find whether nurses in endoscopy units develop asthma under current working conditions in endoscopy units. To obtain analytically reliable data on exposure concentrations of glutaraldehyde (GA) vapour in endoscopy units, and to relate them to individual hygiene and work practices. To characterise any exposure-response relations between airborne GA and the occurrence of work related symptoms (WRSs). Due to the growing concern about the perceived increase in WRSs among workers regularly exposed to biocides, all of whom work within a complex multiexposure environment, a cross sectional study was designed.

METHODS

Current endoscopy nurses (n=348) from 59 endoscopy units within the United Kingdom and ex-employees (who had left their job for health reasons (n=18) were surveyed. Symptom questionnaires, end of session spirometry, peak flow diaries, skin prick tests (SPTs) to latex and common aeroallergens, and measurements of total immunoglobulin E (IgE) and IgE specific to GA and latex were performed. Exposure measurements included personal airborne biocide sampling for peak (during biocide changeover) and background (endoscopy room, excluding biocide changeover) concentrations.

RESULTS

All 18 ex-employees and 91.4% of the current nurses were primarily exposed to GA, the rest were exposed to a succinaldehyde-formaldehyde (SF) composite. Work related contact dermatitis was reported by 44% of current workers exposed to GA, 56.7% of those exposed to SF composite, and 44.4% of ex-employees. The prevalence of WRSs of the eyes, nose, and lower respiratory tract in current workers exposed to GA was 13.5%, 19.8%, and 8.5% respectively and 50%, 61.1%, and 66.6% in the ex-employees. The mean percentage predicted forced expired volume in 1 second (ppFEV(1)) for ex-employees (93.82, 95% confidence interval (95% CI) 88.53 to 99.11) was significantly lower (p<0.01) than that of current workers exposed to GA (104.08, 95% CI 102.35 to 105.73). Occupational peak flow diaries completed by current workers with WRSs of the lower respiratory tract showed no evidence of bronchial asthma (<15% variation). Six per cent of the population had positive latex SPTs. Positive indications of one GA specific IgE and 4.1% latex specific IgE occurred. There was no conformity between the latex specific IgE and positive SPTs. Positive SPTs to latex were associated with WRSs of dermatitis and ocular WRSs, but no other WRSs. Exposures were above the current maximum exposure limit (MEL) of 0.2 mg/m(3) (0.05 ppm) in eight of the units investigated. A significant relation existed between peak GA concentrations and work related chronic bronchitis and nasal symptoms (after adjustment for types of local ventilation) but not to other WRSs. Peak GA concentrations were significantly higher in units that used both negative pressure room and decontaminating unit ventilation.

CONCLUSION

This study documents a significant level of symptoms reported in the absence of objective evidence of the physiological changes associated with asthma. Ex-employees and current workers with WRSs warrant further study to elucidate the cause and mechanisms for their symptoms. Ventilation systems used for the extraction of aldehydes from the work area may be less effective than expected and due to poor design may even contribute to high peak exposures.

Building sickness syndrome in healthy and unhealthy buildings: an epidemiological and environmental assessment with cluster analysis

OBJECTIVES

Building sickness syndrome remains poorly understood. Aetiological factors range from temperature, humidity, and air movement to internal pollutants, dust, lighting, and noise factors. The reported study was designed to investigate whether relations between symptoms of sick building syndrome and measured environmental factors existed within state of the art air conditioned buildings with satisfactory maintenance programmes expected to provide a healthy indoor environment.

METHODS

Five buildings were studied, three of which were state of the art air conditioned buildings. One was a naturally ventilated control building and one a previously studied and known sick building. A questionnaire was administered to the study population to measure the presence of building related symptoms. This was followed by a detailed environmental survey in identified high and low symptom areas within each building. These areas were compared for their environmental performance.

RESULTS

Two of the air conditioned buildings performed well with a low prevalence of building related symptoms. Both of these buildings out performed the naturally ventilated building for the low number of symptoms and in many of the environmental measures. One building (C), expected to perform well from a design viewpoint had a high prevalence of symptoms and behaved in a similar manner to the known sick building. Environmental indices associated with symptoms varied from building to building. Consistent associations between environmental variables were found for particulates (itchy eyes, dry throat, headache, and lethargy) across all buildings. There were persisting relations between particulates and symptoms (headache, lethargy, and dry skin) even in the building with the lowest level of symptoms and of measured airborne particulates (building B). There were also consistent findings for noise variables with low frequency noise being directly associated with symptoms (stuffy nose, itchy eyes, and dry skin) and higher frequency noise being relatively protective across all buildings.

CONCLUSIONS

This is the first epidemiological study of expected state of the art, air conditioned buildings. These buildings can produce an internal environment better than that of naturally ventilated buildings for both reported symptoms and environmental variables. The factors associated with symptoms varied widely across the different buildings studied although consistent associations for symptoms were found with increased exposure to particulates and low frequency noise.

Environmental exposure to air pollution and allergens and peak flow changes

Laboratory-based studies have shown that ozone and nitrogen dioxide can potentiate the effect of allergen in sensitized asthmatic subjects, but it is not known whether this interaction is important under natural exposure conditions. Thirty-five subjects with clinical diagnoses of asthma or chronic obstructive pulmonary disease and with a provocative dose causing a 20% fall in forced expiratory volume in one second methacholine <12.25 micromol (using the Yan method) kept peak expiratory flow (PEF) records for a 4-week period during late summer, with concurrent measurement of spore and pollen counts and pollution levels. Multiple regression analysis was then used to determine the effect on PEF of aeroallergen, and of the interaction between aeroallergen and pollutant levels. A statistically significant interaction was demonstrated between total spore count and ozone, but not nitrogen dioxide. Mean PEF fell in association with increasing spore count (same-day and 24-h lag level) and PEF variability increased with increasing spore count (24-h lag level only); both changes were greater the higher the prior ozone level. These results suggest that ozone can potentiate the effect of aeroallergens in subjects with bronchial hyperreactivity under natural exposure conditions. However, the effect was small, and the clinical significance of the interaction requires further study.

Magnetic resonance imaging of intestinal necrosis in preterm infants

BACKGROUND AND OBJECTIVE

Noninvasive diagnosis of intestinal necrosis is important in planning surgery in preterm infants with necrotizing enterocolitis (NEC). We aimed to assess the potential of magnetic resonance imaging (MRI) for the diagnosis of intestinal necrosis.

STUDY PARTICIPANTS AND METHODS

Abdominal MRI scans were performed in a group of preterm infants with suspected NEC and compared with surgical findings and to MRI results in a group of control infants. In addition, MRI was performed in 2 preterm infants with suspected NEC who did not require surgery.

RESULTS

Six infants with a median birth weight of 1220 g (range, 760-1770 g) and median gestational age at birth of 30 weeks (range, 28-34 weeks) were studied at a median postnatal age of 10 days (range, 4-19 days). Four infants had a bubble-like appearance in part of the intestinal wall, intramural gas, and an abnormal fluid level within bowel lumen. At surgery, NEC was found in 5 infants and sigmoid volvulus in 1. The site of the bubble-like appearance corresponded to the site of intestinal necrosis at surgery. Four control infants with a median birth weight of 1500 g (range, 730-2130 g) and a median gestational age of 31 weeks (range, 26-36 weeks) had abdominal MRI at a median postnatal age of 8 days (range, 4-70 days). None of the above findings were seen in any control infant. The bubble-like appearance was not seen in the 2 infants with suspected NEC who did not require surgery.

CONCLUSION

Abdominal MRI allows the noninvasive diagnosis of bowel necrosis. This may aid the timing of surgical intervention in preterm infants with a clinical diagnosis of NEC.gangrene, ischemia, MRI, necrotizing enterocolitis.

Magnetic resonance imaging of the brain in a cohort of extremely preterm infants

To define magnetic resonance imaging (MRI) appearances of the brain in extremely preterm infants between birth and term, a sequential cohort of infants born at a gestational age <30 weeks was studied with a dedicated neonatal magnetic resonance scanner. Images of infants (n = 41) with a median gestational age of 27 weeks (range 23 to 29 weeks) were initially obtained at a median age of 2 days (range 1 to 20 days) and then repeatedly studied; 29 (71%) infants had MRI at a median gestational age of 43 weeks (range 38 to 52 weeks) (term MRI). On the initial MRI scan 28 of 41 infants had abnormalities: either intraventricular hemorrhage, germinal layer hemorrhage, ventricular dilatation, or diffuse and excessive high signal intensity in the white matter on T(2)-weighted images. When magnetic resonance images for preterm infants at term gestation were compared with those of infants in the control group born at term, 22 of 29 infants had dilatation of the lateral ventricles, 24 of 29 had squaring of the anterior or posterior horns of the lateral ventricles, 11 of 29 had a widened interhemispheric fissure or extracerebral space, and 22 of 29 had diffuse and excessive high signal intensity in the white matter. There were no cases of cystic periventricular leukomalacia. We conclude that MRI abnormalities are commonly seen in the brain of preterm infants on whom images are obtained within 48 hours of birth and that further abnormalities develop between birth and term. A characteristic appearance of diffuse and excessive high signal intensity in the white matter on T(2)-weighted images is associated with the development of cerebral atrophy and may be a sign of white matter disease. These MRI appearances may help account for the high incidence of neurodevelopmental impairment in extremely preterm infants.

Ventilatory function and personal breathing zone dust concentrations in Lancashire textile weavers

BACKGROUND

To report findings on ventilatory function and estimations of concentrations of personal breathing zone dust in Lancashire textile weavers. Weaving room dust is considered to be less harmful than that encountered in the cardroom or spinning room and weavers are generally thought to have less respiratory disability than carders or spinners. However, this occupational group has not been extensively studied.

METHODS

Each person was given a respiratory symptom questionnaire (modified Medical Research Council, UK, questionnaire on respiratory diseases). Ventilatory function tests, forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were performed on each person. A representative sample of workers from each occupational group underwent dust sampling in their personal breathing zone. Dust concentrations and ventilatory tests were analysed statistically with the Student's t test, Pearson's correlation coefficient, and forward step regression for relations with symptoms and environmental factors. Significance was p > or = 0.05.

RESULTS

The FEV1 and FVC were reduced in workers with respiratory symptoms (non-specific chest tightness, shortness of breath, persistent cough, and wheezing) as well as in preparation room workers, current and former smokers, Asians, those working with predominantly cotton fibre (> 50% cotton) and starch size. Mean total dust concentration (pd1) in the personal breathing zone was 1.98 mg/m3. The corresponding value for total dust with large fibres lifted off the filter paper (pd2) was 1.55 mg/m3. There was a strong correlation (r = 0.94, p < 0.0001) between pd1 and pd2. Non-specific chest tightness was predicted by low dust concentrations and persistent cough by high dust concentrations. On regression analysis, impairment of ventilatory function (FEV1, FVC) was predicted by smoking, male sex, age, not working in the weaving shed, not being white, and personal dust concentrations.

CONCLUSIONS

The FEV1 and FVC were impaired in smokers and those exposed to high dust concentrations in the personal breathing zone. Symptoms were inconsistently related to dust concentrations in the personal breathing zone.

Respiratory symptoms in Lancashire textile weavers

OBJECTIVES

To investigate a large population of cotton textile weavers for reported respiratory symptoms relative to occupational factors, smoking, and exposure to dust. Cotton processing is known to produce a respiratory disease known as byssinosis particularly in the early processes of cotton spinning. Relatively little is known about the respiratory health of the cotton weavers who produce cloth from spun cotton. By the time cotton is woven many of the original contaminants have been removed.

METHODS

1295 operatives from a target population of 1428 were given an interviewer led respiratory questionnaire. The presence of upper and lower respiratory tract symptoms were sought and the work relatedness of these symptoms determined by a stem questionnaire design. Also occupational and demographic details were obtained and spirometry and personal dust sampling performed.

RESULTS

Byssinosis was present in only four people (0.3%). Chronic bronchitis had a moderate overall prevalence of about 6% and was related predominantly to smoking. There were several other work related respiratory symptoms (persistent cough 3.9%, chronic production of phlegm 3.6%, chest tightness 4.8%, wheezing 5.4%, and breathlessness 2.3%). All of these were predicted predominantly by smoking (either past or present), with no consistent independent effect of exposure to dust. Work related eye and nasal symptoms were more common (10.4% and 16.9% respectively).

CONCLUSION

Byssinosis is a rare respiratory symptom in cotton weaving. Other work related respiratory symptoms were reported but their presence was predominantly related to smoking with no consistent effects of exposure to dust.

Reasons for testing and exposure sources among women of childbearing age with moderate blood lead levels

The purpose of this study was to examine the circumstances under which women receive blood lead tests in New York State and to characterize the sources of lead exposure among women of childbearing age with moderate blood lead levels. Telephone interviews were conducted with 135 women between the ages of 18 and 45, with blood lead levels from 10 through 25 micrograms/dl, were used to collect information on the reason for their blood lead test and possible sources of lead exposure. It was found that the two most common reasons to be tested for blood lead were workplace screening (47%) and pregnancy (27%). Occupational exposure was the primary source of lead exposure in this population (46%). Another common source of lead exposure was home renovation (24%). A significant proportion (31%) of women with blood lead levels from 10 through 25 micrograms/dl had no known current source of lead exposure. Based on New York's sample, there are a significant number of women of reproductive age with potentially fetotoxic blood lead levels.

Attempting to control mite allergens with mechanical ventilation and dehumidification in British houses

BACKGROUND

Allergen avoidance is of considerable interest in the treatment and even prevention of asthma. Attempts to control house dust mites have included environmental manipulation in homes in an attempt to reduce humidity below a level that favors mite survival. This appears to have some benefit in Scandinavia, but a previous attempt with mechanical ventilation heat pump recovery (MVHR) units in the UK failed to achieve the desired results.

OBJECTIVE

We report a study using an additional central dehumidification modification of the MVHR (MVHRcd) in an attempt to reduce allergen levels in houses of asthmatic subjects.

METHODS

Ten houses of asthmatic patients allergic to dust mites and 10 architectural control houses were studied. The active houses were fitted with an MVHRcd unit in November/December 1994 and activated in January 1995. The active and control houses were monitored continuously for internal temperature and humidity by using digital sensors in the asthmatic and control bedrooms. Dust samples were collected to determine allergen levels at baseline (January 1994) and 3, 6, 9, and 15 months after switching on the units.

RESULTS

The winter seasonal average humidity fell from 50% relative humidity (RH) in control bedrooms to 37% RH in asthmatic bedrooms compared with 72% RH in the ambient air as measured on the intake of the MVHRcd systems. There was no corresponding change in seasonal mean temperature within the houses. Although the temperature and humidity weekly and seasonal means remained below the study target of 45% RH or 7 g/kg absolute humidity at 21 degrees C, there were transient rises in humidity detected by the sensors in the houses with MVHRcd systems. Allergen levels fell both in active and control houses during the study period, but there was no significant advantage gained from the installation of MVHRcd systems.

CONCLUSION

The MVHRcd system failed to confer a benefit in terms of mite allergen reduction despite apparently adequate control of temperature and humidity.

Comparative personal exposures to organic dusts and endotoxin

The aims of the study were to provide valid comparative data for personal exposures to dust and endotoxins for different occupations and to calculate comparative data for the contamination of organic dusts with endotoxin. Nine different occupational settings were studied, drawn from the textile, agricultural and animal handling industries. Samples were collected by personal sampling techniques, using the Institute of Occupational Medicine (IOM) sampling head, glass fibre filters and rechargeable sampling pumps. The dust exposures were calculated by gravimetric analysis and using the calculated volume of air sampled were expressed as mg/m3. Endotoxin exposures were measured using a simple water extraction from the collected dusts, followed by a quantitative turbidimetric assay. Results were expressed as ng/m3, using the calculated volume of air sampled. In addition, the levels of the contamination of dusts with endotoxin for individual industries were expressed as ng/mg of collected dust. Two hundred and fifty-nine samples, collected from 9 different industries and across 36 different sites were analysed. This represented a sampling rate of 25% for the total work force. The average sampling time was 4.62 h. For all the dusts collected, a significant correlation between the collected dust and endotoxin was seen (r = 0.7 and p < 0.001). The highest dust exposures occurred during cleaning activities (grain handling: 72.5 mg/m3). The individuals exposed to the highest median level of dust and endotoxin were the animal handlers (poultry handlers, dust: 11.53 mg/m3, endotoxin: 71,995 ng/m3). Weaving and mushroom cultivation had the lowest exposures for dust and endotoxins. The mostly highly contaminated dusts (median values expressed as ng of endotoxin per mg of collected dust) were found in the animal handling (poultry: 1,030 ng/mg, swine: 152 ng/mg) and cotton spinning (522 ng/mg) industries. Processing of cotton and wool fibres was found to reduce the levels of contamination of dusts with endotoxin. In the study, valid comparative data for personal exposures to organic dusts and endotoxins have been presented. The highest exposures were found amongst animal handlers and during cleaning activities. The results highlight that dust exposures are greater in a number of industries than the set exposure standards. In addition, endotoxin exposures are found to be greater than levels at which harmful effects have been demonstrated.

Prevalence and predictors of work related respiratory symptoms in workers exposed to organic dusts

OBJECTIVES

The aims of this study were to document the prevalence of work related upper and lower respiratory tract symptoms in workers exposed to organic dusts and to identify variables predictive of their occurrence.

METHODS

A cross sectional survey with an administered questionnaire (a previously validated adaptation of the Medical Research Council (MRC) respiratory questionnaire) was performed. Symptoms were classified as work related by their periodicity. Demographic data, smoking habits, and occupational histories were recorded. Personal exposures to dust and endotoxin were measured and individual subjects ascribed an exposure value specific to occupation, site and industry. Cox's regression techniques were used to identify variables predictive of work related upper and lower respiratory tract symptoms. Information was stored using Dbase 3 and analysed with SPSS.

RESULTS

1032 Workers (93% of the target population) were studied in nine different industries. The highest prevalences of work related lower respiratory tract symptoms (38.1%), upper respiratory tract symptoms (45.2%), and chronic bronchitis (15.5%) were found among poultry handlers. White workers were significantly more likely to complain of upper and lower respiratory tract symptoms. An individual in the swine confinement industry had a symptom complex compatible with byssinosis. Increasing current personal exposures to dust or endotoxin were found to be predictive of upper and lower respiratory tract symptoms, chronic bronchitis, and byssinosis. In a univariate analysis a relation between current exposures and the organic dust toxic syndrome was found. Present smoking and previously documented respiratory tract illness were significantly predictive of work related lower respiratory tract symptoms. Women were more likely to report work related upper respiratory tract symptoms.

CONCLUSIONS

People exposed to organic dusts may have a high prevalence of work related respiratory tract symptoms which are related to dust exposures and smoking habits. Action should be taken to reduce exposures to dust and endotoxin and stopping smoking should be promoted among workers exposed to organic dusts to reduce morbidity.

A comparison of performance of two personal sampling heads for cotton dust

Cotton dust sampling for monitoring worker exposure was traditionally performed by work area sampling. A change to an exposure limit based on personal sampling has recently been agreed. The choice of sampling head for personal monitoring exposure was hampered by the use of two different sampling heads in the major epidemiological studies of textile workers which had incorporated personal sampling techniques. The purpose of this study was to compare the results of exposure measurements using these two sampling heads. This study has examined the performance of the two sampling heads, by performing dual sampling on cotton operatives during normal working activities. Each operative included wore two samplers randomly allocated to left or right side. A minimum of 200 minutes of sampling was accepted and the relative concentrations calculated. The IOM total dust sampler produced repeatedly higher measurements than the Manchester head. The ratio overall was 1.33 (95% C.I. 1.20-1.49). The performance was similar across the ranges of dust exposure from low (< 1 mg/m3-ratio 1.28), medium (1-3 mg/m3-ratio 1.43) to high exposure (> 3 mg/m3-ratio 1.24). The two heads give reproducibly proportionate dust measurements with approximately 30% greater results obtained with the IOM total dust sampler. Either dust sampling head could be used for worker monitoring and the results adjusted accordingly for reference to the Maximum Exposure Limit.

Chronic bronchitis in textile workers

BACKGROUND

Exposure to cotton is known to produce a specific occupational disease known as byssinosis. A large population of textile workers was investigated to determine whether such exposure was also associated with chronic bronchitis once other possible aetiological factors had been accounted for.

METHODS

A total of 2991 workers were investigated for the presence of symptoms compatible with chronic bronchitis. An MRC adapted respiratory questionnaire and MRC definition of chronic bronchitis were used for diagnostic labelling. Current and lifetime exposure to dust was estimated by personal and work area sampling, and the use of records of retrospective dust levels previously measured over the preceding 10 years. Airborne endotoxin exposure was measured using a quantitative turbidometric assay. Lung function tests were performed to measure forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). A control group of workers exposed to man-made fibre textiles was identified. The comparative prevalence of chronic bronchitis in the two populations was assessed, allowing for sex, age, smoking habit, and ethnic origin. Two case referent studies were also performed; cases of chronic bronchitis were separately matched with controls from the cotton and control populations to determine the effect of the symptomatic state on lung function.

RESULTS

After controlling for smoking (pack years), workers in a cotton environment were significantly more likely to suffer from chronic bronchitis and this was most marked in workers over 45 years of age (odds ratio 2.51 (CI 1.3 to 4.9); p < 0.01). Regression analysis of all possible influencing parameters showed that cumulative exposure to cotton dust was significantly associated with chronic bronchitis after the effects of age, sex, smoking, and ethnic group were accounted for (p < 0.0005). In the intra-cotton population case control study a diagnosis of chronic bronchitis was associated with a small decrement in lung function compared with controls: percentage predicted FEV1 in cases 81.4% (95% CI 78.3 to 84.6), controls 86.7% (84.9 to 88.5); FVC in cases 89.9% (95% CI 87.0 to 92.9), controls 94.6% (92.8 to 96.4). After controlling for cumulative past exposure and pack years of smoking the effect of the diagnostic state remained significant for both FEV1 (p < 0.01) and FVC (p < 0.05).

CONCLUSIONS

Chronic bronchitis is more prevalent in cotton workers than in those working with man-made fibre and exposure is additive to the effect of smoking. The diagnosis of chronic bronchitis is associated with a small but significant decrement in lung function.

Reduction in humidity as a method of controlling mites and mite allergens: the use of mechanical ventilation in British domestic dwellings

BACKGROUND

Low humidity is an important limiting factor for mite population growth. Reducing humidity can therefore be used as a method to control mites within the home.

OBJECTIVE

This study investigated the effect of mechanical ventilation heat recovery (MVHR) units on house dust mites and mite allergen Der p 1 in typical homes in the North-West of England.

METHODS

Mite counts and Der p 1 levels were measured at 3-monthly intervals over a period of 1 year in 18 houses (nine with MVHR units and nine architecturally matched control houses). Paired dust samples were collected using a vacuum cleaner with an air-flow rate 451/sec, adapted to collect the sample onto a preweighed filter paper. A 1 m2 area of bedroom carpet, living room carpet and mattress was sampled for 2 min. Indoor temperature and relative humidity (RH) levels were recorded for a period of 1 week before and after the winter period (November and February: 3 and 6 months data sets). The environmental questionnaire was completed at the beginning and at the end of the study.

RESULTS

No difference in either Der p 1 concentrations or mite counts in any of the sampling sites at 3, 6, 9 and 12 months as compared with the baseline values was found, both within and between the groups (P > 0.01). The measured levels of RH performed in autumn and winter were found to be lower in the MVHR houses compared to the architectural controls. The indoor temperature during each period did not differ between the groups. Questionnaire data showed that the severity of condensation improved in the MVHR homes, whilst during the winter period, the severity of condensation had increased in the architectural control group.

CONCLUSIONS

The MVHR unit does not reduce indoor humidity to levels capable of retarding the mite population growth and decreasing mite allergens in the type of houses predominantly found in the mild and humid climate of the North-West of England.

Lung function in Lancashire cotton and man made fibre spinning mill operatives

OBJECTIVES

This survey was conducted to investigate current lung function levels in operatives working with cotton and man made fibres. Dust concentrations, smoking history, and occupational details were recorded so that factors influencing lung function could be identified.

METHODS

A cross sectional study of respiratory symptoms and lung function was made in 1057 textile spinning operatives of white caucasian extraction. This represented 96.9% of the total available working population to be studied. Most (713) worked currently with cotton. The remainder worked with man made fibre. Lung function was assessed by measuring forced expiratory volume in one second (FEV1) and forced vital capacity (FVC). Exposure to cotton dust was measured in the work area and personal breathing zones, and retrospective exposure to cotton dust over a working life was estimated with accurate work history and best available hygiene data.

RESULTS

3.5% of all operatives had byssinosis, 55 (5.3%) chronic bronchitis, 36 (3.5%) work related persistent cough, 55 (5.3%) non-byssinotic work related chest tightness, and 56 (5.3%) work related wheeze. A total of 212 static work area dust samples (range 0.04-3.23 mg/m3) and 213 personal breathing zone samples (range 0.14-24.95 mg/m3) were collected. Percentage of predicted FEV1 was reduced in current smokers (mean 89.5, 95% confidence interval (95% CI) 88-91) in comparison with non-smokers (93.1, 90.5-94.1) and FVC was reduced in operatives currently working with man made fibre (95.3, 93.8-96.9) in comparison with cotton (97.8, 96.6-99.0). Regression analysis identified smoking (P < 0.01), increasing age (P < 0.01), increasing time worked in the waste room (P < 0.01), and male sex (P < 0.05) as being associated with a lower FEV1 and FVC. Current and retrospective cotton dust exposures did not appear as predictor variables in the regression analysis although in a univariate analysis, FEV1 was reduced in those operatives exposed to high dust concentrations assessed by personal and work area sampling.

DISCUSSION

This study has documented loss of lung function in association with exposure to cotton dust. Those operatives with work related symptoms had significantly lower FEV1 and FVC than asymptomatic workers. Although lung function seemed to be affected by high dust exposures when operatives were stratified into high and low exposure groups, regression analysis did not identify current dust concentrations as an independent factor influencing loss. Smoking habit was found to explain most of the measured change in FEV1 and FVC. It is likely that smoking and dust exposure interact to cause loss of lung function in cotton textile workers.

Pharmacokinetics, oral bioavailability and tissue distribution of azithromycin in cats

Azithromycin is the first of a class of antibiotics classified as azalides. In an initial experiment four cats were given a single dose of azithromycin 5 mg/kg orally (p.o.), followed 2 weeks later by a single intravenous bolus (i.v.) dose of 5 mg/kg. Subsequently, six cats were given [14C]azithromycin p.o. in a single dose of 5.4 mg/kg for the study of tissue distribution and metabolism. In both experiments, serial blood samples were collected and the plasma assayed for unchanged azithromycin to determine various pharmacokinetic parameters. After p.o. administration, bioavailability was 58% and absorption rapid with a tmax of 0.85 +/- 0.72 h and a Cmax of 0.97 +/- 0.65 microgram/mL. The harmonic mean terminal t1/2 after i.v. administration was 35 h. Tissue half-lives varied from 13 h in fat to 72 h in cardiac muscle. Three metabolites were identified in bile. Unchanged azithromycin accounted for 100% of the total radioactivity in lung and skin tissues when assayed. In comparison with other species, the bioavailability in cats is higher than in humans but lower than in dogs. As in the dog, > 50% of the azithromycin-related material in feline bile was unchanged azithromycin.

Effects of air pollution on symptoms and peak expiratory flow measurements in subjects with obstructive airways disease

BACKGROUND

Evidence from laboratory studies suggests that air pollution can produce bronchoconstriction and respiratory symptoms in selected subjects, but the relevance of these findings to exposure to natural pollution is unclear. This study was performed to determine whether air pollution at typical levels found in the UK has demonstrable effects on respiratory function and symptoms in subjects with airways disease.

METHODS

Seventy five adult patients with diagnoses of asthma or chronic obstructive pulmonary disease (COPD) were studied for a period of four weeks during which they kept records of their peak expiratory flow (PEF) rates, symptoms (wheeze, dyspnoea, cough, throat and eye irritation), and bronchodilator use. Thirty six patients in whom the provocative dose of methacholine causing a 20% fall in FEV1 was below 12.25 mumol were classified as reactors. Ambient air pollution was measured with absorption spectroscopy.

RESULTS

There were modest but significant increases in PEF variability, bronchodilator use, and wheeze with increasing sulphur dioxide levels; bronchodilator use, dyspnoea, eye irritation, and minimum PEF readings were related to ozone levels. In the subgroup of reactors falls in mean and minimum peak flow and increases in wheeze, dyspnoea, and bronchodilator use were associated with increases in levels of both sulphur dioxide and ozone. Some associations were seen with pollution levels on the same day, but for others the pollution effects appeared to be delayed by 24 or 48 hours. Pollution levels did not breach the WHO guide levels during the course of the study.

CONCLUSIONS

Increases in environmental levels of ozone and sulphur dioxide are associated with adverse changes in peak flow measurements and both ocular and respiratory symptoms in subjects with obstructive airways disease. Although the peak flow and symptom changes were modest, they occurred at pollution levels below current WHO guide levels.

Domiciliary air filtration units, symptoms and lung function in atopic asthmatics

Air infiltration units (AFUs) incorporating a high efficiency particulate air filter are theoretically able to remove almost all potential airborne allergens. This may have implications for subjects with allergic lower respiratory disease. AFUs were placed in the living room of 12 atopic asthmatics, and the internal filters were inserted and removed in a double-blind fashion. No difference in subjective symptom scoring, spirometry or bronchial reactivity was demonstrated. Peak expiratory flow rate (PEFR) variability was significantly improved from baseline readings, and there was a trend towards higher mean PEFRs when the filters were present in the AFU. Trends towards lower levels of airborne micro-organisms were also demonstrated when the filters were present, however no effect upon total airborne dust and airborne Der pI could be demonstrated.

Ocular and nasal irritation in operatives in Lancashire cotton and synthetic fibre mills

OBJECTIVES

To document the prevalence of work related ocular (eyeWRI) and nasal (noseWRI) irritation in workers in spinning mills of cotton and synthetic textile fibres and to relate the prevalence of symptoms to atopy, byssinotic symptoms, work history, and measured dust concentrations in the personal breathing zone and work area.

METHODS

A cross sectional study of 1048 cotton workers and 404 synthetic fibre workers was performed. A respiratory questionnaire was given to 1452 workers (95% of the total available population). Atopy was judged by skin prick tests to three common allergens. Work area cotton dust sampling (WAdust) was carried out according to EH25 guidelines in nine of the 11 spinning mills included in the study. Personal breathing zone dust concentrations were assessed with the IOM sampler to derive total dust exposure (PTdust) and a concentration calculated after the removal of fly (Pless).

RESULTS

3.7% of all operatives complained of symptoms of byssinosis, 253 (17.5%) complained of eyeWRI and 165 (11%) of noseWRI. These symptoms did not relate to atopy or byssinosis, or correlate univariately with any measure of cotton dust exposure (noseWRI v WAdust r = 0.153, PTdust r = 0.118, eyeWRI v WAdust r = 0.029, PTdust r = 0.052). Both of these symptoms on logistic regression analysis were related to being of white origin (P < 0.001), female sex (P < 0.001), and younger age (P < 0.001). With regression analysis, there was a negative relation between dust concentration and prevalence of symptoms.

CONCLUSION

Work related ocular and nasal irritation are the most common symptoms complained of by cotton textile workers. There was no relation between these symptoms and atopy, byssinosis, or dust concentration. It is likely that they relate to as yet unidentified agents unrelated to concentration of cotton dust.

Respiratory symptoms and dust exposure in Lancashire cotton and man-made fiber mill operatives

A cross-sectional study of work-related symptoms and cotton dust exposure was made in 404 man-made fiber and 1,048 cotton operatives in Lancashire spinning mills; 39 cotton-exposed operatives (3.7%) had symptoms of byssinosis. This was associated on regression analysis with cumulative lifetime cotton dust exposure (p < 0.001), total years spent carding (p < 0.001), and currently working in the carding area (p = 0.0041). Smoking habit did not differ significantly between byssinotic and nonbyssinotic workers. Other work-related symptoms were common: chronic bronchitis (CB) and persistent cough. The prevalence of CB correlated positively with dust exposure (r = 0.59). Cotton dust sampling was performed in the work area (SDPRES) and personal breathing zone (PD1). A retrospective estimate of lifetime cotton dust exposure based on SDPRES correlated best with the prevalence of byssinosis (r = 0.797), although correlations with PD1 (r = 0.709) and SDPRES (r = 0.594) were also significant.

A phase I study of the toxicity of regional hyperthermia with systemic warming

This study examines the consequences of allowing moderate systemic hyperthermia during regional heating of the abdomen and pelvis in 29 patients participating in Phase I studies of hyperthermia combined with chemotherapy or radiation therapy. In Group 1 (20 patients, 42 treatments), systemic temperatures were limited by employing surface cooling, while in Group 2 (9 patients, 24 treatments), surface warming and insulation were used so that systemic temperature would rise. Mean time-averaged oral temperatures were 38.4 degrees C and 39.9 degrees C for Groups 1 and 2, respectively. Time-averaged mean regional temperatures were 40.2 +/- 0.7 degrees C and 41.5 +/- 0.2 degrees C for Groups 1 and 2, respectively (p < .001). Regional temperatures > or = 41.0 degrees C were achieved by 64% of Group 1 and all Group 2 patients. The mean time-averaged power required was significantly lower for Group 2 (453 W vs 740 W; p = .032), as was the incidence of pain. Mean maximum pulse rate was significantly higher in Group 2, although this was not associated with symptoms. Allowing systemic temperature to rise decreased power requirements and treatment-related pain, at the cost of an asymptomatic increase in heart rate. The results suggest that regional heating may be more readily achieved in the setting of elevated systemic temperature.

A study of the performance and comparability of the sampling response to cotton dust of work area and personal sampling techniques

In order to compare and contrast the sampling response to cotton dust of two forms of dust sampling 85 work areas were identified over a 2-year period for investigation in eight Lancashire spinning mills. Three hundred and five work area dust samples were undertaken and 252 personal dust samples were performed. Operatives who spent a minimum of 80% of their working shift in the area in which work area sampling was also performed were selected for personal sampling. Work area dust exposures have recently shown an upward trend, with highest concentrations occurring in the ring spinning room (median 1.15 mg m-3, range 0.82-2.06). Personal dust samples showed a reduction in dust exposures as cotton processing progressed, from a high in the opening room (median value of 6.24 mg m-3, range 1.0-41.5) to a minimum of 1.02 mg m-3 (range 0.30-0.93) in the winding room. The ratio of measured personal sampling dust exposure to work area sampling exposure was used to compare the relative performance of the two techniques. This ratio was highest in the early processes. There was a 7.8-fold difference in measurement between the two techniques in the opening processes, falling to 4.9 in carding and 4.2 in the other card-room processes. However in ring spinning the ratio was only 1.4, suggesting a degree of comparability in the methods at this stage of processing. The value rose to 2.5 for the last stage (winding). Respiratory disease is known to occur predominantly in the early stages of processing (opening and carding) where high dust concentrations are found using the personal technique. These data support the use of personal sampling for setting exposure limits to cotton dust in preference to the current recommended method using work area sampling techniques, which may significantly underestimate dust exposure in the high risk work areas and is outdated.

Lung function, bronchial reactivity, atopic status, and dust exposure in Lancashire cotton mill operatives

A total of 645 cotton mill operatives were administered a respiratory questionnaire. Of these, 85 (13.2%) complained of one or more work-related respiratory symptoms: 23 (3.6%) had byssinosis and the remaining 62 had symptoms not conforming to byssinosis (nonbyssinotic symptomatics, NBS). All byssinotic, 56 NBS, and 84 matched asymptomatic operatives underwent pulmonary function testing (FEV1 and FVC), skin testing to common allergens, and histamine bronchial challenge. Work area and personal breathing zone cotton dust concentrations were assessed, and a cumulative cotton dust exposure index was calculated for each individual. Byssinotic, NBS, and asymptomatic operatives all had reduced FEV1; observed mean liters (95% CI); predicted mean: byssinosis, 2.36 (2.09 to 2.63), 3.02; NBS, 2.94 (2.71 to 3.17), 3.29; and asymptomatic, 3.12 (2.95 to 3.29), 3.31. Only byssinotic subjects had evidence of impaired FVC: 3.31 (2.97 to 3.65), 3.69. The majority of byssinotic operatives (18 of 23) had bronchial hyperreactivity (BHR) in comparison with 21 of 56 NBS and 14 of 84 asymptomatic operatives. Mean log PD20 (95% CI) values were significantly lower in the byssinotic group -0.72 (-1.42, -0.02) than in NBS 0.57 (0.08, 1.06) and asymptomatic subjects 0.57 (-0.26, 1.39). The distribution of atopy did not differ significantly between groups, and lung function did not differ significantly between atopic and nonatopic subjects. The cumulative cotton dust exposure index was the only dust parameter to be significantly greater in those with BHR (mean mg-yr/m3 [95% CI] 14.13 [13.1 to 15.1]) than those with normal reactivity [5.35 (3.9 to 6.8)].

Germfree technique for the rearing of kittens--a research tool

Techniques to derive and rear germfree kittens (Felis catus) for biomedical research were explored and refined. The isolator units, equipment, sterilization procedures, husbandry techniques, and safety issues are discussed. This method proved to be successful for the surgical derivation and hand-rearing of germfree kittens.

Effects of hypertension and sympathetic denervation on cerebral blood flow in newborn pigs

To investigate the potential role of sympathetic nerves in preventing pronounced increases in cerebral blood flow, we evaluated the effects of abrupt hypertension on the cerebral circulation of newborn pigs with intact cerebral sympathetic innervation and after cerebral sympathetic denervation. Epinephrine infusion was used to induce abrupt increases in mean (+/- SEM) arterial pressure (innervated pigs, 62 +/- 3 mm of Hg to 115 +/- 3 mm of Hg; denervated pigs, 71 +/- 4 mm of Hg to 132 +/- 4 mm of Hg) that remained increased for the 3 minutes of the study. Abrupt hypertension increased blood flow to all brain regions. In denervated pigs, the increased flow to the cerebrum was prolonged, compared with that in pigs with intact sympathetic innervation. Differences between pigs of the innervated and denervated groups were not apparent, with respect to blood flow to any other region (caudate region, brain stem, cerebellum). In newborn pigs, sympathetic nerves may attenuate hypertension-induced increases in blood flow to the cerebrum, but do not appear to affect flow to the rest of the brain.

Regional hyperthermia for deep-seated malignancies using the BSD annular array

Forty-four patients were treated using the BSD-1000 Annular Phased Array between April 1983 and December 1986. There were 32 pelvic, nine abdominal, two extremity, and one thoracic sites treated. Mean tumour volume was 646 cc. Thirty-nine patients had concurrent radiation therapy, receiving a mean dose of 38 Gy. Mean average temperature was 41.0 +/- 1.4 degrees C. Most patients experienced local or systemic toxicity, requiring temporary treatment interruption in 33 patients, and termination of treatment in eight. Chronic complications were seen in four, but these were in patients receiving high total radiation doses as well. There were six complete and five partial responses. Among the 32 patients with pelvic tumours, mean tumour volume was 317 cc, mean radiation dose was 42 Gy, and mean average temperature was 41.3 +/- 1.2 degrees C. There were five complete and four partial responses. Achieving tumour temperatures greater than or equal to 42 degrees C with the annular array is difficult, due to both systemic and local toxicity. To improve clinical hyperthermia for thoracic, abdominal, and pelvic tumours, new technologies such as steerable phased array microwave systems; scanned, focused ultrasound; and permanently implantable thermoregulating ferromagnetic seeds, or new approaches such as using drugs to alter blood flow, or combining hyperthermia with antineoplastic drugs or biological agents, will be necessary.

Indomethacin does not alter the circulating catecholamine response to asphyxia in the neonatal piglet

The response of circulating catecholamines to asphyxia in unanesthetized, spontaneously breathing neonatal piglets was measured before and after treatment with indomethacin. Prior to treatment with indomethacin, baseline levels [geometric mean, pg/ml (95% confidence limits)] of D, E, and N were 162 (99-266), 174 (52-579), and 380 (286-506), respectively. Inhalation of 10% O2/9% CO2 for 20 min caused significant increases in arterial levels of all three catecholamines to 389 (230-659, 1514 (993-2306), and 3802 (2731-5293), respectively. Treatment with indomethacin (5 mg/kg, intravenous) did not significantly alter either baseline levels of the catecholamines or the levels after 20 min of the asphyxiating gas. In time control piglets, baseline levels and the response to asphyxia were similar before and after placebo. These results suggest that the circulating catecholamine response to asphyxia of the neonatal piglet is independent of the prostaglandin system.

Vasopressin responses to asphyxia and hemorrhage in newborn pigs

Vasopressin may be important in maintenance of arterial pressure and redistribution of cardiac output in hypotensive and asphyxiated newborns. We used chronically instrumented, unanesthetized, 4-day-old pigs to investigate the effects of hypotensive hemorrhage and asphyxia on plasma vasopressin concentration and to determine the effects of cyclooxygenase inhibition on these responses. Asphyxia [arterial O2 partial pressure (PaO2) = 40-50 Torr, arterial CO2 partial pressure (PaCO2) = 60-80 Torr) increases plasma lysine vasopressin (LVP) from 2.2 +/- 0.8 to 52.4 +/- 15.0 microU/ml. Neither the baseline nor stimulated plasma LVP was affected by indomethacin (5 mg/kg) or meclofenamate (5 mg/kg). Hemorrhage (30 ml/kg) increased plasma LVP from 2.8 +/- 0.8 to 163.4 +/- 28.1 (20 min) and 135.1 +/- 18.5 microU/ml (60 min). The effects of vehicle and indomethacin (5 mg/kg) 20 min after hemorrhage on plasma LVP 60 min after hemorrhage were not different. Changes in plasma vasopressin caused by asphyxia and hemorrhage in the unanesthetized newborn pig are similar to the responses observed in adults of other species. This study does not suggest that prostanoids are involved in these responses in newborn pigs.