Evidence for widespread changes in the structure, composition, and fire regimes of western North American forests.

Implementation of wildfire- and climate-adaptation strategies in seasonally dry forests of western North America is impeded by numerous constraints and uncertainties. After more than a century of resource and land use change, some question the need for proactive management, particularly given novel social, ecological, and climatic conditions. To address this question, we first provide a framework for assessing changes in landscape conditions and fire regimes. Using this framework, we then evaluate evidence of change in contemporary conditions relative to those maintained by active fire regimes, i.e., those uninterrupted by a century or more of human-induced fire exclusion. The cumulative results of more than a century of research document a persistent and substantial fire deficit and widespread alterations to ecological structures and functions. These changes are not necessarily apparent at all spatial scales or in all dimensions of fire regimes and forest and nonforest conditions. Nonetheless, loss of the once abundant influence of low- and moderate-severity fires suggests that even the least fire-prone ecosystems may be affected by alteration of the surrounding landscape and, consequently, ecosystem functions. Vegetation spatial patterns in fire-excluded forested landscapes no longer reflect the heterogeneity maintained by interacting fires of active fire regimes. Live and dead vegetation (surface and canopy fuels) is generally more abundant and continuous than before European colonization. As a result, current conditions are more vulnerable to the direct and indirect effects of seasonal and episodic increases in drought and fire, especially under a rapidly warming climate. Long-term fire exclusion and contemporaneous social-ecological influences continue to extensively modify seasonally dry forested landscapes. Management that realigns or adapts fire-excluded conditions to seasonal and episodic increases in drought and fire can moderate ecosystem transitions as forests and human communities adapt to changing climatic and disturbance regimes. As adaptation strategies are developed, evaluated, and implemented, objective scientific evaluation of ongoing research and monitoring can aid differentiation of warranted and unwarranted uncertainties.

Work-related asthma in cobalt-exposed workers.

OBJECTIVE: Workers exposed to cobalt may develop two lung conditions, asthma or lung fibrosis. There is a relative lack of awareness of the risk of lung disease from cobalt exposure. METHODS: The state of Michigan requires physicians, and hospitals to report work-related asthma (WRA). A standardized telephone interview of each reported case was conducted. An industrial hygienist evaluated the reported cases's workplace, and a physician reviewed the results to confirm the diagnosis. This is a population-based case series of all workers in whom the exposure to cobalt was confirmed as likely responsible for WRA from 1988 to 2017. We also included an illustrative case report and data on the workplace evaluations. RESULTS: Of the 35 cases identified, 77% were males, 97.1% were white, and 62.9% had a history of smoking cigarettes. Fifteen (44%) cases were involved in manufacturing cutting tools and machine tool accessories. Symptoms improved in 28 cases (80%) when away from work. Fourteen cases (40%) had emergency department visits, while 10 (28.6%) had been hospitalized for breathing problems. Spirometry had been performed for 33 (94.3%) cases. Only 13 (37.1%) reported they were informed by a doctor that their asthma was work-related. Twenty-six inspections were conducted at 21 different workplaces, where 498 coworkers were interviewed, 55 (11%) of which had respiratory symptoms at work. Six workplaces were cited for cobalt air level higher than permissible limits. These inspections resulted in $29,380 in penalties. CONCLUSIONS: WRA secondary to cobalt is associated with significant morbidity. Most of the cases were unaware of their medical diagnosis.

Neuromas as the cause of pain in the residual limbs of amputees. An ultrasound study.

AIM: To explore the morphology of neuromas and to determine the differences, if any, between asymptomatic and symptomatic neuromas using ultrasound. MATERIALS AND METHODS: Eighty patients with symptomatic neuromas were included in this retrospective review. High-resolution ultrasound examination was performed. Transducer pressure allowed real-time analysis of both symptomatic and asymptomatic neuromas. Quantifiable assessment of pain by the patient assigned a pain score of 0, 1, 2, or 3, to each neuroma. RESULTS: One hundred and fifty-nine neuromas were identified in total. Fifty-three neuromas were asymptomatic (pain score=0), very severe pain was recorded in 54 (pain score=3), 16 neuromas were mildly painful (pain score=1) and 36 were moderately painful (pain score=2). The average number of neuromas per patient was 1.98, and the average number of symptomatic neuromas per patient was 1.3. There was no correlation between pain score and patient age, neuroma volume, amputation type, and time since amputation. CONCLUSIONS: High-resolution ultrasound can distinguish between asymptomatic and symptomatic neuromas. Patient age, time since amputation, the type of amputation, and the neuroma volume were not related to the presence of pain.

HLA class II DPB1 and DRB1 polymorphisms associated with genetic susceptibility to beryllium toxicity.

OBJECTIVES: Chronic beryllium disease (CBD) is a hypersensitivity granulomatous pulmonary disease caused by exposure to the metal beryllium (Be²âº). Our objective was to extend current knowledge of the genetics of beryllium disease by examining all HLA-DPB1 and HLA-DPR1 gene polymorphisms and the interactions between them. METHODS: DNA-based typing of HLA-DPB1 and HLA-DRB1 loci at the allele level was performed on 65 CBD, 44 beryllium sensitised (BeS) but without CBD and 288 non-affected, beryllium exposed controls. RESULTS: The DPßE69 residue regardless of zygosity, but particularly if present on non-*0201 alleles, was of primary importance for the development of CBD and BeS, while other negatively charged residues DPßDE55, 56 and DPßDE84, 85 incrementally increased, although not independently, the risk. The DPßE69 positive alleles with charge -7 or -9 were associated with both CBD and BeS. The polymorphic residues DPßE69, DPßDE55, 56 and DPßDE84, 85 were responsible for the -9 charge and the first two residues for the -7 charge. CONCLUSIONS: In the absence of DPßE69, DRßE71 is a risk factor for CBD and BeS. DPßE69 and DRßE71 are adjacent to other amino acids that are also negatively charged, suggesting that the positively charged Be²âº modifies the local environment of the epitopes in a way that promotes interactions between peptides and T cells and results in CBD. Finally, the protective effect of the DPB1*0201 positive haplotype may involve particular polymorphisms outside of the DPB1 gene.

A descriptive study of work aggravated asthma.

BACKGROUND AND AIMS: Work related asthma (WRA) is one of the most frequently reported occupational lung diseases in a number of industrialised countries. A better understanding of work aggravated asthma (WAA), as well as work related new onset asthma (NOA), is needed to aid in prevention efforts. METHODS: WAA and NOA in the United States were compared using cases reported to the National Institute for Occupational Safety and Health (NIOSH) from four state Sentinel Event Notification Systems for Occupational Risks (SENSOR) surveillance programmes for 1993-95. RESULTS: A total of 210 WAA cases and 891 NOA cases were reported. WAA cases reported mineral and inorganic dusts as the most common exposure agent, as opposed to NOA cases, in which diisocyanates were reported most frequently. A similar percentage of WAA and NOA cases still experienced breathing problems at the time of the interview or had visited a hospital or emergency room for work related breathing problems. NOA cases were twice as likely to have applied for workers' compensation compared with WAA cases. However, among those who had applied for worker compensation, approximately three-fourths of both WAA and NOA cases had received awards. The services and manufacturing industrial categories together accounted for the majority of both WAA (62%) and NOA (75%) cases. The risk of WAA, measured by average annual rate, was clearly the highest in the public administration (14.2 cases/10(5)) industrial category, while the risk of NOA was increased in both the manufacturing (3.2 cases/10(5)) and public administration (2.9 cases/10(5)) categories. CONCLUSIONS: WAA cases reported many of the same adverse consequences as NOA cases. Certain industries were identified as potential targets for prevention efforts based on either the number of cases or the risk of WAA and NOA.

N-linked sialyated sugar receptors support haematopoietic cell-osteoblast adhesions.

Haematopoietic progenitor cells proliferate and develop predominantly when they adhere to bone marrow stromal cells such as osteoblasts. Therefore, changes in adhesion may be a common mechanism by which stem cells survive, mature and properly traffic between the bone marrow and the circulation. To characterize these adhesion molecules, we reduced the bone marrow cavity to a simple adhesion assay between KG1a (a CD34+ haematopoietic cell line) and osteosarcoma monolayers (MG-63 or SaOS-2). The data demonstrated that adhesion was mediated by cell-to-cell rather than cell-to-matrix contact, was sensitive to trypsin, calcium chelators and glycosylation inhibitors. Selective pretreatment attributed the constitutive binding to N-linked glycans on KG1a. When carboprocessing was inhibited later at the high mannose intermediate (via deoxymannojirimycin), adhesion was retained. Surprisingly, binding of KG1a to SaOS-2 increased past constitutive levels as doses of tunicamycin or deoxymannojirimycin dropped. Selective pretreatment suggested that this 'inducible' binding resides with molecule(s) on SaOS-2. If the terminal sialic acid was digested (via neuraminidase), this induced response was duplicated. These data, verified in primary cells, suggest that the initial tethering between blood and bone cells in this model is probably due to heavily glycosylated, rapidly processed protein(s) on both cell types.

Is there a haemodynamic advantage associated with cuffed arterial anastomoses?

The development of intimal hyperplasia at arterial bypass graft anastomoses is a major factor responsible for graft failure. A revised surgical technique, involving the incorporation of a small section of vein (vein cuff) into the distal anastomosis of PTFE grafts, results in an altered distribution of intimal hyperplasia and improved graft patency rates, especially for below-knee grafts. Numerical simulations have been conducted under physiological conditions to identify the flow behaviour in a typical cuffed bypass model and to determine whether the improved performance of the cuffed system can be accounted for by haemodynamic factors. The flow patterns at the cuffed anastomosis are significantly different to those at the conventional end-to-side anastomosis. In the former case, the flow is characterised by an expansive, low momentum recirculation within the cuff. Separation occurs at the graft heel, and at the cuff toe as the blood enters the recipient artery. Wall shear stresses in the vicinity of the cuff heel are low, but high shear stresses and large spatial gradients in the shearing force act on the artery floor during systole. In contrast, a less disturbed flow prevails and the floor shear stress distribution is less adverse in the conventional model. In conclusion, aspects of the anastomotic haemodynamics are worsened when the cuff is employed. The benefits associated with the cuffed grafts may be related primarily to the presence of venous material at the anastomosis. Therefore, caution is advised with regard to the use of PTFE grafts, pre-shaped to resemble a cuffed geometry.

Numerical investigation of the haemodynamics at a patched arterial bypass anastomosis.

Intimal hyperplasia at arterial bypass graft anastomoses is a major factor responsible for graft failure. A revised surgical technique, incorporating a Taylor vein patch into the distal anastomosis of PTFE grafts, results in a decrease in intimal hyperplasia and improved patency rates. Numerical simulations of pulsatile, non-Newtonian blood flow through life-like femorodistal bypass models have been performed to determine whether haemodynamic benefits arise from the modified geometry of the Taylor anastomosis. In a conventional bypass, the distal anastomotic flow exhibited considerable spatial and temporal variations. Steep spatial gradients in the shearing force acted along the floor during systole. The effect of the Taylor geometry was to reduce gradually the momentum of the blood approaching the junction. Thus, flow disturbances were abated, undesirable flow separation at the toe was diminished, and a less adverse floor shear stress distribution prevailed in that case. Intimal thickening should be alleviated at the toe in the Taylor model where separation is reduced, and where the thrombogenic graft surface is replaced with a vein patch. Intimal hyperplasia on the floor may be inhibited in the Taylor model due to more favourable shear stresses. The improved flow through the patched anastomosis should contribute to its enhanced performance.

What is the most cost-effective way to identify silica problem worksites?

BACKGROUND: State based surveillance systems to identify cases of silicosis have been developed over the past 18 years to target worksite interventions to reduce the incidence of silicosis. Using data from the Michigan silicosis surveillance system, we conducted an analysis to determine the most cost-effective way to identify problem worksites. METHODS: The initial reporting source of all 470 confirmed cases of silicosis reported to the Michigan surveillance system from 1989 to 1995 was identified. The cost of identifying confirmed cases, worksites, problem worksites, silica problem worksites, and the number of current silica-exposed workers was determined for four reporting sources: hospitals; physicians; workers' compensations; and death certificates. RESULTS: Hospital reports were the first to identify 67% of the confirmed cases, 74% of the worksites, and 58% of the problem worksites. Physician reports initially identified 17% of confirmed cases, 15% of worksites, and 26% of problem worksites. Workers' compensation records initially identified 11% of confirmed cases, 4% of worksites, and 8% of problem worksites. Death certificates initially identified 5% of confirmed cases, 7% of worksites, and 8% of problem worksites. Hospital reports were the most cost-effective way to identify cases (US$ 143), worksites (US$ 313), and problem worksites (US$ 454). CONCLUSIONS: Hospital discharge records identified the greatest number of confirmed cases and problem worksites and was the most cost-effective approach to identify both individuals with silicosis and worksites with problems.

Endovascular stent-graft repair of primary aortocaval fistula with an abdominal aortoiliac aneurysm.

A primary aortocaval fistula is present in less than 1% of all abdominal aortic aneurysms. Until recently, surgical repair was the only method of treatment and was associated with a high incidence of morbidity and mortality. With the rapid development of aortic stent-graft technique, endovascular stent-graft repair may offer an alternative to the management of this often fatal condition. We report a case of an aortoiliac aneurysm with an aortocaval fistula successfully treated with endovascular stent-grafting. The unique hemodynamic changes, technical problems, and complications associated with this case are discussed, and the literature is reviewed.

Kidney disease and silicosis.

AIM: To determine the prevalence of kidney disease in a cohort of individuals with silicosis. METHODS: Review of medical records and questionnaires from patients reported to a state surveillance system for silicosis. Reporting of individuals with silicosis is required by state law. All individuals with silicosis reported as required by law to the State of Michigan. Individuals included in this article were reported from 1987 to 1995. Cases were reported by hospitals, physicians, the state workers' compensation bureau, or from death certificates. Only individuals who met the criteria for silicosis developed by the National Institute for Occupational Safety and Health (NIOSH) were included. RESULTS: Medical records were reviewed of 583 individuals with confirmed silicosis. This was mainly a population of elderly men. Ten percent of the 583 silicotics were found to have some mention of chronic kidney disease, and 33% of the 283 silicotics who we had laboratory tests on had a serum creatinine level >1.5 mg/dl. An association between kidney disease and age and between kidney disease and race was found among this cohort of 583 silicotics. Individuals with silicosis were more likely to have a serum creatinine level >1.5 mg/dl than age- and race-matched controls. However, no relationship between duration of exposure to silica or profusion of scarring on chest X-ray and prevalence of kidney disease or elevated creatinine levels was found. CONCLUSIONS: This study confirms previous case reports and epidemiologic studies of end-stage renal disease that found an association between kidney disease and exposure to silica. The epidemiologic data are conflicting on the mechanism by which silica causes kidney disease and are compatible with silica being able to cause kidney disease by both an autoimmune and direct nephrotoxic effect. Chronic kidney disease should be considered as a complication of silicosis.

Hand-assisted laparoscopic surgery (HALS) with the HandPort system: initial experience with 68 patients.

OBJECTIVE: To evaluate the feasibility and potential benefits of hand-assisted laparoscopic surgery with the HandPort System, a new device. SUMMARY BACKGROUND DATA: In hand-assisted laparoscopic surgery, the surgeon inserts a hand into the abdomen while pneumoperitoneum is maintained. The hand assists laparoscopic instruments and is helpful in complex laparoscopic cases. METHODS: A prospective nonrandomized study was initiated with the participation of 10 laparoscopic surgical centers. Surgeons were free to test the device in any situation where they expected a potential advantage over conventional laparoscopy. RESULTS: Sixty-eight patients were entered in the study. Operations included colorectal procedures (sigmoidectomy, right colectomy, resection rectopexy), splenectomy for splenomegaly, living-related donor nephrectomy, gastric banding for morbid obesity, partial gastrectomy, and various other procedures. Mean incision size for the HandPort was 7.4 cm. Most surgeons (78%) preferred to insert their nondominant hand into the abdomen. Pneumoperitoneum was generally maintained at 14 mmHg, and only one patient required conversion to open surgery as a result of an unmanageable air leak. Hand fatigue during surgery was noted in 20.6%. CONCLUSIONS: The hand-assisted technique appeared to be useful in minimally invasive colorectal surgery, splenectomy for splenomegaly, living-related donor nephrectomy, and procedures considered too complex for a laparoscopic approach. This approach provides excellent means to explore, to retract safely, and to apply immediate hemostasis when needed. Although the data presented here reflect the authors' initial experience, they compare favorably with series of similar procedures performed purely laparoscopically.

Caged ATP - an internal calibration method for ATP bioluminescence assays.

ATP bioluminescence, based on the firefly luciferase system, is used for the rapid determination of hygienic practices in the food industry. This study has demonstrated the use of caged ATP as an internal ATP standard and quantified the effects of industrial cleansing solutions, alcoholic beverages and pH on firefly luciferase activity. The light signal was quenched 6-47% by five cleansing solutions at standard working concentrations. Ethanol at 1% (v/v) inhibited bioluminescence by 15% (w/v) whereas concentrations above 4% enhanced the light output. The light signal was quenched by 20-25% at pH values below pH 4 and above pH 10.

Why most workers with occupational repetitive trauma do not file for workers' compensation.

Despite the availability of no fault insurance for wage replacement and medical care costs, the majority of workers diagnosed with an occupational disease do not apply for workers' compensation. The objective of the study was to determine the reasons why workers diagnosed with work-related musculoskeletal disease did not apply for workers' compensation benefits. A cross-sectional study of 1598 individuals diagnosed with neck, upper extremity, and low back work-related musculoskeletal disease from April to June 1996 was performed. All individuals were interviewed over the telephone using a standardized questionnaire. The questionnaire included questions about the precipitating event; demographics; health limitations; mood; pain level; and attitudes toward their health care provider, fellow workers, management, work environment, and filing for workers' compensation. Whenever possible, standardized questions from previous surveys were used. The interviewed individuals with work-related musculoskeletal disease were reported by health care practitioners as required by the state of Michigan's occupational disease reporting law. Workers reported during 12 weeks in the spring of 1996 by a Michigan health care professional as having a neck, back, or upper extremity musculoskeletal disorder were eligible to participate. Among the 2703 reports received, 490 individuals could not be reached, 22 did not speak English, 12 had died or were too incapacitated by other medical conditions, and 581 refused. We interviewed 59% of all eligible workers and 73% of all workers who were reachable and capable of responding in English. Only 25% of workers diagnosed with musculoskeletal disease filed a workers' compensation claim. The factors significantly associated with filing a claim were (1) increased length of employment (> 21 years: odds ratio [OR], 3.01, 95% confidence interval [CI], 1.31 to 6.90); 11 to 20 years: OR, 2.34, 95% CI, 1.01 to 5.47; 6 to 10 years: OR, 1.76, 95% CI, 0.73 to 4.25; 1 to 5 years: OR, 2.36, 95% CI, 1.03 to 5.42; < 1 year: OR, 1.00; (2) lower annual income (< $40,000: OR, 1.75, 95% CI, 1.06 to 2.88 vs > or = $80,000: OR, 1.00); (3) workers' dissatisfaction with coworkers (OR, 1.76, 95% CI, 1.01 to 3.06); (4) physician restrictions on activity (OR, 2.16, 95% CI, 1.55 to 3.00); (5) type of physician providing treatment (specialist, including surgeon or orthopedist: OR, 3.63, 95% CI, 2.37 to 5.55); physical and occupational therapist: OR, 2.15, 95% CI, 1.35 to 3.43); family practitioner: OR, 1.33, 95% CI = 0.89 to 2.01; company physician: OR = 1.00); (6) off work > or = 7 days (OR, 14.85, 95% CI, 10.57 to 20.85); (7) decreased current health status (OR, 0.82, 95% CI, 0.70 to 0.96); and (8) increased severity of illness (OR, 1.24, 95% CI, 1.06 to 20.88). This study showed that only 25% of workers with a work-related musculoskeletal condition filed for workers' compensation and refutes the common perception that an individual with a work-related problem is likely to file a workers' compensation claim. The strongest predictors of who would file were those factors associated with the severity of the condition. Other factors were increasing length of employment, lower annual income, and worker dissatisfaction with coworkers. Our study population consisted mainly of unionized autoworkers, and our findings may not be generalizable to the total workforce.

Human osteoblast-like cells and osteosarcoma cell lines synthesize macrophage inhibitory protein 1alpha in response to interleukin 1beta and tumour necrosis factor alpha stimulation in vitro.

Recent investigations have demonstrated that macrophage inhibitory protein 1alpha (MIP-1alpha) plays a critical role in haematopoiesis. In part, MIP-1alpha limits the differentiation of early haematopoietic cells, thereby ensuring that sufficient quantities of blood precursors are available to meet haematopoietic demands. MIP-1alpha is produced by cells of the marrow microenvironment (marrow stromal cells) in response to a variety of stimuli, including interleukin 1beta (IL-1beta) and tumour necrosis factor alpha (TNF-alpha). Our recent investigations demonstrated that normal human osteoblast-like cells (HOBs) maintain the early phenotype of haematopoietic precursors, like other members of the bone marrow stroma. Although the precise molecular mechanisms for these observations have not been determined, the production of MIP-1alpha remains one such possibility. In the present study, we investigated whether cells of the osteoblast lineage under basal, IL-1beta and/or TNF-alpha stimulation produce MIP-1alpha. We observed that IL-1beta and TNF-alpha stimulated HOBs and human osteosarcoma cells to rapidly express MIP-1alpha mRNA and to secrete large quantities of the protein. MIP-1alpha mRNA and protein was not, however, detected under basal conditions. Perhaps more importantly, enriched human CD34+ bone marrow cells in co-culture may be capable of stimulating the expression of MIP-1alpha mRNA by HOBs in vitro. These findings suggest that human osteoblast-like cells may produce MIP-1alpha in vivo to support haematopoiesis at sites where osteoblasts and haematopoietic cells are closely associated.

Surveillance of work-related asthma in selected U.S. states using surveillance guidelines for state health departments--California, Massachusetts, Michigan, and New Jersey, 1993-1995.

PROBLEM/CONDITION: Cases of work-related asthma (WRA) are sentinel health events that indicate the need for preventive intervention. WRA includes new-onset asthma caused by workplace exposure to sensitizers or irritants and preexisting asthma exacerbated by workplace exposures. REPORTING PERIOD: This report reviews cases of WRA identified by state health departments from January 1, 1993, through December 31, 1995, as well as follow-up investigations of cases and associated workplaces conducted through June 30, 1998. DESCRIPTION OF THE SYSTEMS: State-based surveillance and intervention programs for WRA are conducted in California, Massachusetts, Michigan, and New Jersey as part of the Sentinel Event Notification Systems for Occupational Risks (SENSOR) cooperative agreement program, initiated by CDC's National Institute for Occupational Safety and Health (NIOSH). RESULTS: From 1993 through 1995, a total of 1,101 cases of WRA were identified by SENSOR surveillance staff members in California, Massachusetts, Michigan, and New Jersey. Of these 1,101 cases, 19.1% were classified as work-aggravated asthma, and 80.9% were classified as new-onset asthma. Objective evidence substantiating asthma work-relatedness was documented in the medical records of 3.4% of WRA cases identified in the two states (Michigan and New Jersey) where medical records are routinely reviewed for this information. Indoor air pollutants, dusts, cleaning materials, lubricants (e.g., metalworking fluids), and diisocyanates were among the most frequently reported causes of WRA. In addition, a well-recognized cause of occupational asthma - natural rubber latex - was identified in a new setting, the healthcare industry. The most common industries associated with WRA cases included transportation equipment manufacturing (19.3%), health services (14.2%), and educational services (8.7%). Air sampling for agents known to induce occupational asthma was performed in Michigan for comparison with established federal time-weighted average exposure limits. Sixteen (13.4%) of 119 workplaces tested had airborne concentrations exceeding NIOSH recommended exposure limits (RELs); 11 (9.1%) of 121 workplaces had concentrations exceeding permissible exposure limits (PELs) of the Michigan Occupational Safety and Health Act (MIOSHA) program. INTERPRETATION: The surveillance data findings confirm well-recognized causes of asthma and have identified new putative causes (e.g., cleaning materials and metalworking fluids). Because the surveillance program depends on physicians' recognizing asthma work-relatedness and reporting diagnosed cases, the data are considered an underestimate of the magnitude of the WRA problem. The data also indicate that physicians are not commonly performing objective physiologic tests to substantiate a WRA diagnosis. Workplace findings suggest a need to evaluate existing exposure standards for specific agents known to induce occupational asthma (e.g., diisocyanates). Case-based surveillance can help improve the recognition, control, and prevention of WRA. The SENSOR model also provides a mechanism for workers and physicians to request workplace investigations aimed at primary prevention for other workers. PUBLIC HEALTH ACTION: NIOSH and state health department representatives are working to establish a long-term agenda for state-based surveillance of work-related conditions and hazards. The results from the SENSOR WRA programs described in this report support inclusion of WRA as a priority condition warranting surveillance at the state level.

An evaluation of the incidence of work-related asthma in the United States.

The objective of the study was to estimate the incidences of physician-diagnosed cases of work-related asthma (WRA) in Michigan and the entire United States. The statewide surveillance system for WRA in Michigan receives reports primarily from three sources: physicians, hospital discharge data, and worker's compensation claims. Knowledge of the overlap in reports from these sources was used in conjunction with capture-recapture methods to estimate the total number of diagnosed cases of WRA, and incidence rates were calculated using the estimated number of civilian employees in Michigan as the population at risk. For the entire United States, the product of a national incidence rate for asthma among adults and estimates of the proportion that is work-related was used. A total of 933 cases of WRA were reported to the Michigan surveillance program during 1988-1995, of which 904 were reported by at least one of the three main sources and equaled an average incidence of 27 cases/10(6)/year. This estimate was less than the range of estimates 58 to 204 cases/10(6)/year in Michigan arrived at using the capture-recapture methods. The national estimates of WRA ranged from 63 to 441 cases/10(6)/year. The authors' indirect estimates are closer to estimates from Canada, Sweden, and Finland than most existing direct estimates in the United States, but probably still underestimates the magnitude of WRA incidence because of the limitations of physician recognition of the work-relatedness of asthma among adults.

Connective tissue disease and silicosis.

BACKGROUND: To determine the prevalence of connective tissue disease in a cohort of individuals with silicosis, we reviewed the medical records and questionnaires from individuals reported from 1987 to 1995 to a state surveillance system for silicosis. Reporting of individuals with silicosis is required by state law. Cases were reported by hospitals, physicians, the state workers' compensation bureau, or from death certificates. Only individuals who met the criteria for silicosis developed by the National Institute for Occupational Safety and Health (NIOSH) were included in the analysis. RESULTS: A questionnaire was completed for all 583 cases. Medical records were available for 463. There were 24 people with rheumatoid arthritis, one with scleroderma, and one with systemic lupus erythematosus. All were men. The prevalence of rheumatoid arthritis was 5.2% (relative risk (RR) 2.73, 95% confidence limit (CL) 1.75-4.06). The prevalence of scleroderma was 0.2% (RR 15.65, 95% CL 0.21-87.03) and the prevalence of systemic lupus erythematosus was 0.2% (RR 11.37, 95% CL 0.15-63.23). This is an approximately 2.5-15-fold increased risk for these connective tissue diseases compared to estimated prevalences in the general population. Individuals with silicosis and connective tissue disease did not differ from individuals with silicosis but without connective tissue disease by race, age, type of industry where exposed to silica, history of tuberculosis, whether or not they had applied for workers' compensation, and whether or not they had progressive massive fibrosis on chest x-ray. CONCLUSION: Although the association between scleroderma and silicosis has been more widely reported in the literature, the prevalence of rheumatoid arthritis was greater than the prevalence of scleroderma or systemic lupus erythematosus among a cohort of individuals with silicosis.

Osteoblasts and The Hematopoietic Microenvironment.

Cells of the bone marrow are chiefly dedicated to two processes; the production of blood, and the production of bone that houses the hematopoietic organ. The majority of our understanding of these processes comes from data focused on one of these functions. Yet, in vivo the processes are intermixed. Our recent data demonstrate that human osteoblast-like cells have important accessory roles in hematopoiesis. These data include the demonstration that human osteoblast-like cells; support the growth of primitive human hematopoietic progenitors (CD34(+) cells) in short and long term cultures and, synthesize multiple cytokines believed to regulate hematopoiesis. Based upon anatomic and developmental findings characterizing hematopoietic cells in close approximation with endosteal cells, and these findings, we hypothesize that osteoblasts play a critical role in hematopoietic cells development in vivo.

Cardiopulmonary exercise testing in the pre-operative assessment of patients for repair of abdominal aortic aneurysm.

We have investigated the value of cardiopulmonary exercise testing in the pre-operative assessment to patients for abdominal aortic aneurysm repair. Thirty-six patients were entered into the study. All had a pre-operative clinical assessment and investigations including chest radiograph, electrocardiograph, spirometry and echocardiogram with measurement of left ventricular ejection fraction. Each patient performed a symptom limited treadmill exercise test using a STEEP protocol with on-line measurement of respiratory gas exchange. Patients were followed up for 12 months post-operatively by review of casenotes. Thirty out of 36 patients had surgical repair of abdominal aortic aneurysm. There was 1 death in the perioperative period and 2 deaths in the following 12 months. Seven other patients suffered post-operative complications. There were no significant differences in left ventricular ejection fraction, spirometry and peak achieved oxygen consumption (PVO2) between those patients who died or who had post-operative complications and those who had not. However, PVO2 < 20 ml/min/kg was found in 70 per cent of patients who had complications compared with 50 per cent of those who had not. Also 4 patients considered medically unfit for surgery all had PVO2 < 20 ml/min/kg. Cardiopulmonary exercise testing with measurement of PVO2 may be helpful in identifying patients more at risk of post-operative complications but should not be used in isolation without through clinical assessment.