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D G Kern

Publications and source records attributed to D G Kern.

At least 19 recordsLinked to original sources
PubMed1995

Rapid and precise quantification of HIV-1 RNA in plasma using a branched DNA signal amplification assay.

The level of human immunodeficiency virus type 1 (HIV-1) RNA in human plasma has been quantitated directly with use of a solid-phase nucleic acid hybridization assay, based on branched DNA (bDNA) signal amplification technology with chemiluminescent detection. Signal amplification is accomplished by the incorporation of sites for 1,755 alkaline phosphatase-labeled probes per genome of HIV-1, after successive hybridization of target-specific oligonucleotides and bDNA amplifier molecules. The assay is performed in microwells, much like an immunoassay, and is amenable to routine laboratory use. Reproducibility and specificity studies indicated that the bDNA method was precise and showed no reactivity with seronegative donors. HIV-1 RNA levels were quantitated for 348 seropositive specimens, with a detection rate of 83% for those specimens from patients with < 500 CD4+ T-cell counts. Plasma RNA levels were found to change with disease stage, and in response to antiviral therapy. Quantitation of HIV-1 RNA in the plasma of HIV-1-infected patients, with use of the bDNA assay, may be a useful method for monitoring HIV-1 disease progression and therapeutic response.

Acyclovir↗
PubMed1994

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.

Humans↗
PubMed1994

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.

Adult↗
PubMed1994

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.

Adult↗
PubMed1993

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.

DNA, Viral↗
PubMed1993

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.

Adult↗
PubMed1993

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.

Adult↗
PubMed1993

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.

Adult↗
PubMed1992

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.

Air Pollutants, Occupational↗
PubMed1991

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.

Accidents, Occupational↗
PubMed1991

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.

Asbestosis↗
PubMed1990

Treating asthma.

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Asthma↗