Direct and quantitative detection of HIV-1 RNA in human plasma with a branched DNA signal amplification assay.

AIM: To determine the relative effect of sample matrix on the quantitation of HIV RNA in plasma. METHOD: Two HIV-positive specimens were diluted into five and 10 different HIV-negative plasma samples, respectively. Branched DNA signal amplification technology and reverse-transcriptase polymerase chain reaction were used to measure the viral load. RESULTS: In one sample the viral load by polymerase chain reaction ranged from undetectable to 1.9 x 10(5) copies/ml, and the branched DNA results ranged from 2.6 x 10(4) to 4.2 x 10(4) HIV RNA equivalent/ml. In the other sample the corresponding figures were 6.3 x 10(4) to 5.5 x 10(5) copies/ml and 5.7 x 10(4) to 7.5 x 10(4) HIV RNA equivalents/ml. CONCLUSION: In contrast to reverse-transcriptase polymerase chain reaction the branched DNA signal amplification assay does not require a separate extraction step or enzymatic amplification of the target. Therefore this measurement is less affected by the sample matrix and the signal generated is directly proportional to the viral load.

Auscultated forced expiratory time as a clinical and epidemiologic test of airway obstruction.

OBJECTIVE: Seeking an inexpensive, readily available, clinical, screening, and field surveillance test of airway obstruction, we determined the validity of current dogma that forced expiratory time (FET) is a good clinical test of airway obstruction yet is of no epidemiologic use given excessive intrasubject variability. SUBJECTS AND METHODS: Two hundred twenty-nine white male plumbers and pipefitters were evaluated by spirometry, chest roentgenography, and a standardized respiratory questionnaire during a union-sponsored asbestos screening program. Subjects were classified as having large airway obstruction (LAO), small airway obstruction (SAO) alone, or no obstruction, on the basis of standard spirometric prediction equations. Two physicians, blinded to clinical and spirometric data, independently measured FET while auscultating the trachea with a stethoscope. The FET was defined as the time taken for an individual to forcefully exhale through an open mouth from total lung capacity until airflow became inaudible. Five such times were recorded for each subject. The mean of the three times having the narrowest range was deemed the FET for calculating test sensitivity and specificity. Based on previous literature, an FET greater than or equal to 6 s was considered abnormally prolonged. RESULTS: Two hundred five subjects completed both spirometry and FET testing; 67 had LAO, 5 SAO, and 133 no obstruction. A total of 83 percent had three FETs reproducible within a range of less than or equal to 1 s. The sensitivity and specificity of FET for LAO were 92 and 43 percent, respectively, while for SAO alone, 60 and 44 percent, respectively. Overall, FET misclassified 56 percent of nonobstructed subjects. Adjusting the normal-abnormal cutoff points for both FET and SAO minimally improved the performance of FET. CONCLUSION: Although FET is a simple, inexpensive, sensitive, and fairly reproducible clinical test of LAO, it cannot be recommended as a clinical or an epidemiologic tool because of its extremely low specificity.

A seroepidemiologic study of Chlamydia pneumoniae in Rhode Island. Evidence of serologic cross-reactivity.

OBJECTIVE: Although Chlamydia pneumoniae is considered a common cause of pneumonia worldwide, the evidence is mainly serologic. Therefore, we examined whether the currently used chlamydial microimmunofluorescence (MIF) antibody test is specific for C pneumoniae infection. DESIGN AND SETTING: Secondary analysis of data from a cohort study of sarcoidosis among the graduates of ten consecutive apprenticeship classes of firefighters and police officers. PARTICIPANTS: One hundred forty-seven young adult men. MEASUREMENTS: Immunoglobulin G and M antibodies to C pneumoniae, 15 serovars of C trachomatis, and 2 strains of C psittaci as measured by MIF. RESULTS: Evidence of previous C pneumoniae and C trachomatis infection (IgG > or = 1:16 yet < 1:512) was present in 108 (73 percent) and 59 (40 percent) subjects, respectively. Serologic evidence of recent C pneumoniae and C trachomatis infection (IgM > or = 1:16 or IgG > or = 1:512) was present in 19 (13 percent) and 14 (10 percent) subjects, respectively. Chlamydia pneumoniae and C trachomatis IgM titers were highly correlated (r = 0.80; 95 percent CI, 0.73 to 0.85) while C pneumoniae and C trachomatis IgG titers were fairly correlated (r = 0.44; 95 percent CI, 0.30 to 0.56). CONCLUSIONS: The C pneumoniae seroprevalence of 86 percent is the highest yet reported. The correlations between C pneumoniae and C trachomatis antibody titers suggest that chlamydial MIF may be less specific than is generally appreciated. Moreover, the observed 13 percent seroprevalence of recent C pneumoniae infection in a healthy working population challenges the serologically based belief that this agent accounts for 6 to 10 percent of community-acquired pneumonia. A more objective, more specific test is needed in the serodiagnosis of C pneumoniae infection.

A clinical and structural comparison of industrial methacholine and provocholine.

Methacholine, provided by industrial sources, has traditionally been used in studies of airways responsiveness. In 1986, a Food and Drug Administration approved formulation of methacholine (Provocholine) was released and replaced industrial methacholine in many pulmonary laboratories. To determine whether methacholine and Provocholine cause an equivalent degree of bronchoconstriction, a double blind, cross-over clinical trial was undertaken. After randomization, 19 medicine residents and respiratory therapists each performed methacholine challenge testing using either methacholine or Provocholine. Forty-eight hours later, each participant returned for repeat challenge testing with the alternate agent. The log of the dose-response slope (logslope) was calculated for each test. The mean logslope with methacholine (-0.15 +/- 1.84) and with Provocholine (-0.26 +/- 1.57) did not differ (paired Student's t test, p = 0.64). Further, excellent agreement was found between each subject's logslope with methacholine and with Provocholine (intraclass correlation coefficient rI = 0.82). Proton beam nuclear magnetic resonance revealed no structural differences between the two compounds. These findings suggest that methacholine from industrial sources and Provocholine are clinically and structurally similar and that the two agents may be used interchangeably in nonspecific bronchial provocation testing.

Flock worker's lung: broadening the spectrum of clinicopathology, narrowing the spectrum of suspected etiologies.

STUDY OBJECTIVES: Workers in the nylon flocking industry recently have been found to be at increased risk of chronic nongranulomatous interstitial lung disease. Although a spectrum of cytologic and histopathologic abnormalities has been observed, nonspecific interstitial pneumonia, lymphoid nodules, and lymphocytic bronchiolitis predominated in the 19 previously reported cases of flock worker's lung. Here we describe five additional patients who appear to expand the histopathologic spectrum and add to the evidence suggesting a causative role for respirable-sized nylon fragments. METHODS: We studied all North American patients (n = 5) found in 1998 to satisfy our previous case definition of flock worker's lung. Two pulmonary pathologists independently reviewed each biopsy specimen. RESULTS: All five patients reported cough and dyspnea. Only one patient had crackles on chest auscultation. High-resolution CT scan, interpreted with attention to subtle ground-glass attenuation, remained a highly sensitive diagnostic test. Pulmonary function tests and plain chest radiograph were less sensitive. One patient's wedge biopsy showed previously described prototypical findings. Two others had transbronchial biopsies showing some of the same features. The fourth patient's wedge biopsy showed desquamative interstitial pneumonia. The fifth patient had bilateral synchronous adenocarcinoma but with radiographic evidence of diffuse interstitial fibrosis. These 5 patients and the 19 patients studied previously were exposed to nylon flock manufactured by a rarely used cutting technology. CONCLUSION: Findings in these five patients appear to broaden the spectrum of the clinicopathology of flock worker's lung and add to the evidence incriminating respirable-sized nylon particulates produced during the manufacture and use of rotary-cut nylon flock.

Developing a competency-based preventive medicine curriculum for medical schools.

Trends in patient morbidity and mortality, cost-effectiveness, and national recommendations mandate that we practice more preventive medicine. To address this need, we set out to develop a comprehensive curriculum in preventive medicine for medical schools. We constructed a competency-based (i.e., performance-based) curriculum with specific educational objectives defined by outcomes. Subject areas were subdivided by life stages, and learning objectives were created separately for epidemiology, assessment, and intervention. We hope that adoption of such an educational blueprint by medical schools will measurably enhance the attitudes, knowledge, and skills necessary for the incorporation of preventive principles into all aspects of clinical medicine.

The unexpected result of an investigation of an outbreak of occupational lung disease.

The author describes the discovery of a cluster of cases of interstitial lung disease among employees of a textile manufacturing plant and the difficulties he and his university-hospital occupational medicine team encountered in attempting to identify the cause of the disease. At first accepted in a consultant capacity by the plant's management, the team met increasing resistance to its efforts as it uncovered evidence of a work-related cause of the disease and attempted ientists to communicate findings important to the health of the public, and the physician's overarching professional responsibility to his or her patients.

Outbreak of the reactive airways dysfunction syndrome after a spill of glacial acetic acid.

The reactive airways dysfunction syndrome (RADS) defines a chronic asthmalike illness with airway hyperresponsiveness that develops within 24 h of a single, brief, highly irritating inhalation exposure. Support for the syndrome has been limited to case reports. A chemical spill, exposing hospital employees to 100% acetic acid, offered an opportunity to more convincingly establish the existence of RADS. All 56 exposed subjects were asked both to complete a questionnaire focusing on their preexposure health status, potential for exposure, and symptom development after the accident, 8 months after the spill, and to undergo methacholine challenge testing to detect airway hyperresponsiveness. An industrial hygienist, blinded to clinical data, estimated each subject's exposure. Preemployment health history forms were reviewed to assess recall bias. The study questionnaire was returned by 51 (91%) subjects; 24 (47%) consented to methacholine challenge, including 7 of the 8 with RADS-consistent symptoms. Diagnostic criteria for RADS were satisfied by none of 7 (0%) subjects with low exposure, 1 of 30 (3.3%) with medium exposure, and 3 of 14 (21.4%) with high exposure (test of trend p value = 0.021). The odds ratio estimate of the relative risk of RADS in subjects with high exposure was 9.8 (95% Cl, 0.902 to 264.6). Neither stratified analysis nor review of the preemployment health history forms revealed evidence of confounding or recall bias, respectively. The reactive airways dysfunction syndrome appears to be a valid clinical entity. Further study of RADS is especially appropriate given increasing evidence that airway inflammation may be etiologically important in all asthma.

Lead poisoning in precious metals refinery assayers: a failure to notify workers at high risk.

Lead poisoning in a precious metals refinery fire assayer and a routine OSHA inspection prompted an investigation of the index facility, a survey of the industry, and efforts to notify assayers of this previously unrecognized hazard. Air and blood samples were obtained at the index facility. Management personnel from all fire assay laboratories in Rhode Island and southern Massachusetts were interviewed. The industry's trade association, OSHA, NIOSH, trade unions, and the media were asked to assist in a nationwide notification effort. Assayers at the index facility had excessive exposures to lead due to an age-old, lead-based assaying method that remains the industry gold standard. Blood lead levels of the three assayers (mean 61.3 micrograms/dl, range 48-86 micrograms/dl) were considerably higher than those of 16 other refinery workers (mean 27.4 micrograms/dl, range 13-49 micrograms/dl). The industry survey revealed inadequate knowledge of both the lead hazard and the applicability of the OSHA lead standard. Notification efforts failed in large part due to economic obstacles. The notification of workers at high risk of lead exposure and the eradication of occupational lead poisoning will require greater attention to economic forces.

Asthma risk and occupation as a respiratory therapist.

In the modern hospital environment, many health care workers are exposed to hazardous substances. Among these hazards are respiratory sensitizers, irritants, and infectious agents. A previous cross-sectional study of Rhode Island respiratory therapists reported an excess risk of asthma after entry into that profession. Before the results of that study were published, we conducted a confirmatory mailed questionnaire survey of 2,086 Massachusetts respiratory therapists and 2,030 physical therapists and physical therapy assistants. Neither the survey questionnaire nor the accompanying cover letter revealed the focus of our investigation. A history of physician-diagnosed asthma was reported by 16% of respiratory therapists and 8% of control subjects. When analysis was restricted to those who developed asthma after entry into their profession, respiratory therapists still had a significant excess, 7.4 versus 2.8%. The odds ratio for respiratory therapy was 2.5 (95% Cl, 1.6 to 3.3) after adjustment for age, family history, atopic history, smoking, and gender. These results confirm the previous report of excess risk of asthma among respiratory therapists. This excess risk develops after entry into the profession and does not appear to be explained by bias or confounding. Efforts should be directed to identifying potential agents responsible for this form of occupational asthma.

Occupational asthma following kapok exposure.

Whether a distinct kapok allergen exists or whether the fiber's allergenicity is due to contamination by other allergens has never been resolved. Several years ago, we evaluated a patient who appeared to develop occupational asthma to kapok. We performed an environmental assessment, cross-shift spirometric testing of the patient's co-workers, and the first reported bronchoprovocation challenge with kapok. The disappearance of the patient's asthma following cessation of kapok exposure, with now 7 years of follow-up, our inability to incriminate any other agent, and the patient's positive specific bronchoprovocation challenge strengthen the evidence, but do not prove definitively, that kapok fiber itself is allergenic.

Asthma in respiratory therapists.

STUDY OBJECTIVE: To test the hypothesis that work as a respiratory therapist is associated with an increased risk of developing asthma. DESIGN: Cross-sectional questionnaire study comparing respiratory therapists with controls (physical therapists and radiologic technologists). Subsequent validation of reported asthma with methacholine challenge studies. SUBJECTS: All respiratory therapists and physical therapists and a random 50% sample of radiologic technologists working in the state of Rhode Island as of June 1986. METHODS: All subjects received a mail questionnaire with questions about the presence or absence of asthma, time of onset, and important covariates. Responses were analyzed for all subjects, and again after excluding those subjects with pre-existing asthma. Subjects who reported physician-diagnosed asthma were asked to have methacholine challenge testing. RESULTS: Respondents included 194 respiratory therapists (response rate, 69.5%) and 517 controls (response rate, 75.3%). After excluding respiratory therapists from the hospital at which the hypothesis was generated, there were 34 respiratory therapists (18.7%) and 30 controls (5.8%) reporting physician-diagnosed asthma. After controlling for age, smoking status, family history, atopic history, and other covariates using logistic regression, respiratory therapy carried an odds ratio of 3.2 (95% CI, 1.9 to 5.5). With analysis restricted to those who developed asthma after entering their profession, the odds ratio for respiratory therapy was 4.6 (95% CI, 2.0 to 10.4). In the validation study, 10 of 14 respiratory therapists (71%) and 6 of 10 controls (60%) had evidence of bronchial hyperreactivity. CONCLUSIONS: These results suggest a previously unrecognized excess of asthma in respiratory therapists. The excess develops after entry into the profession, and does not appear to be explained by confounding, information bias, or selection bias.

Asbestos-related disease in the jewelry industry: report of two cases.

We describe two cases of asbestos-related pulmonary disease in jewelry workers. Exposures occurred during the hand-mixing of asbestos powder used to make jewelry soldering boards.

Malignant mesothelioma in the jewelry industry.

We conducted a clinical, environmental, pathologic, and mineral lung burden investigation of a 61-year-old man with malignant mesothelioma. For 35 years, up until three weeks prior to pneumonectomy, the patient made asbestos soldering forms at a costume jewelry production facility. Only chrysotile asbestos was used at the plant during the last decade of the patient's employment, and recent environmental sampling of the work-place identified no other asbestos fiber type. Anticipating that the patient would add to the very small number of cases of mesothelioma attributable solely to chrysotile, we found instead that the patient's lung tissue contained large numbers of both coated and uncoated amosite asbestos fibers but, surprisingly, no chrysotile. We subsequently learned that a distributor of both chrysotile and amosite supplied the company during the first 25 years the patient was fabricating soldering forms. The findings underscore the futility of estimating environmental exposure to chrysotile on the basis of fiber counts in lung tissue. Although we previously described non-neoplastic asbestos-related disease among patients engaged in similar work, this case, to the best of our knowledge, represents the first report of mesothelioma in the commercial jewelry industry. As such, it prompted us to initiate a public health campaign to replace asbestos soldering forms in this industry with readily available, safer alternatives.

Identification of a galactose-binding lectin on Fusobacterium nucleatum FN-2.

A previous study has suggested that Fusobacterium nucleatum FN-2 contains a galactose-binding protein (lectin) on the cell surface (P. A. Murray, V. Matarese, C. I. Hoover, and J. R. Winkler, FEMS Microbiol. Lett. 40:123-127, 1987). In the present study, the molecular specificity and size of this lectin were investigated by several techniques. Whole-cell affinity chromatography with asialofetuin covalently coupled to Sepharose 6MB demonstrated that 81% of 3H-labeled F. nucleatum were specifically eluted by 0.5 M galactose. Specific binding was calcium dependent and did not occur in the presence of calcium chelators. Binding was inhibited by preincubation with galactose. Agglutination of human parotid saliva by F. nucleatum was also inhibited by galactose and its structural analogs. Inhibition by lactose was 2 times that of galactose, inhibition by p-aminophenyl galactosides was 4 times that of galactose, and inhibition by asialoglycopeptides was 100 times that of galactose. Similar inhibition results were obtained for hemagglutination of neuraminidase-treated erythrocytes. These findings suggest that the binding specificity of F. nucleatum FN-2 is more complex than simply the recognition of the monosaccharide galactose. This is consistent with the concept that lectins considered identical in terms of monosaccharide specificity can recognize fine differences in more complex structures. To identify the specific bacterial component(s) involved in galactose recognition, proteins of F. nucleatum FN-2 were separated on a 4 to 11% gradient sodium dodecyl sulfate slab gel, transferred to nitrocellulose paper to renature bacterial binding sites, and then incubated with 125I-labeled asialofetuin. Autoradiographs of the nitrocellulose revealed a band at a range of Mr 300,000 to 330,000 which was not present when the blots were preincubated with galactose. These data support the concept that F. nucleatum FN-2 possesses a lectin that recognizes galactose and galactose-containing substrates.

Investigation of a unique time-space cluster of sarcoidosis in firefighters.

A unique cluster of three cases of sarcoidosis developed recently among 10 white firefighters who trained together as apprentices in 1979. This led us to hypothesize that firefighters are at increased risk of this condition because of the combined effect of smoke exposure and infection with a communicable agent, such as Chlamydia pneumoniae, a recently proposed cause of sarcoidosis. We conducted a case-finding questionnaire survey of 1,282 active and retired male Providence firefighters and police officers and then evaluated both the index apprenticeship class and two control cohorts by chest radiography, seromarkers of T lymphocyte activation (neopterin and sIL-2R), and chlamydial serology. One additional case of sarcoidosis was identified among the 990 (77%) survey respondents. No new cases were detected in the subsequent laboratory investigation of 46 (87%) firefighters from the index 1979 apprenticeship class, 53 (75%) firefighter controls from the 1974 and 1980 classes, or 50 (30%) police officer controls from 1973-1981 classes. The cohorts did not differ with regard to either C. pneumoniae antibody titers or sIL-2R levels, but serum neopterin was elevated (> 9.0 nmol/L) in 20% (eight of 41) of the index cohort, 22% (11 of 51) of firefighter controls, and 4% (two of 48) of police officers. Logistic regression found firefighting to be the only significant predictor of neopterin elevation (odds ratio 5.8; 95% CI, 1.3 to 26.9). Our results suggest that firefighters may be at risk of T lymphocyte activation. Determining whether this reflects an enhanced risk of lymphocytic alveolitis and whether firefighters are more likely to develop sarcoidosis requires further study.

Flock worker's lung: chronic interstitial lung disease in the nylon flocking industry.

BACKGROUND: Two young men working at a nylon flocking plant in Rhode Island developed interstitial lung disease of unknown cause. Similar clusters at the same company's Canadian plant were reported previously. OBJECTIVE: To define the extent, clinicopathologic features, and potential causes of the apparent disease outbreak. DESIGN: Case-finding survey and retrospective cohort study. SETTING: Academic occupational medicine program. PATIENTS: All workers employed at the Rhode Island plant on or after 15 June 1990. MEASUREMENTS: Symptomatic employees had chest radiography, pulmonary function tests, high-resolution computed tomography, and serologic testing. Those with unexplained radiographic or pulmonary function abnormalities underwent bronchoalveolar lavage, lung biopsy, or both. The case definition of "flock worker's lung" required histologic evidence of interstitial lung disease (or lavage evidence of lung inflammation) not explained by another condition. RESULTS: Eight cases of flock worker's lung were identified at the Rhode Island plant. Three cases were characterized by a high proportion of eosinophils (25% to 40%) in lavage fluid. Six of the seven patients who had biopsy had histologic findings of nonspecific interstitial pneumonia, and the seventh had bronchiolitis obliterans organizing pneumonia. All seven of these patients had peribronchovascular interstitial lymphoid nodules, usually with germinal centers, and most had lymphocytic bronchiolitis and interstitial fibrosis. All improved after leaving work. Review of the Canadian tissue specimens showed many similar histologic findings. Among the 165-member study cohort, a 48-fold or greater increase was seen in the sex-adjusted incidence rate of all interstitial lung disease. CONCLUSIONS: Work in the nylon flocking industry poses substantial risk for a previously unrecognized occupational interstitial lung disease. Nylon fiber is the suspected cause of this condition.