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W Alexander

Publications and source records attributed to W Alexander.

At least 37 records · Page 2Linked to original sources
PubMed1995

Endemic work-related febrile respiratory illness among construction workers.

Construction workers building Denver International Airport (DIA) reported work-related respiratory and flulike symptoms of several months duration. We performed a cross-sectional interview study of 495 randomly selected DIA workers from six contractors in comparison with preplacement workers. We defined cases as workers with two work-attributed lower respiratory symptoms and one work-attributed systemic symptom. Case rates were significantly higher among DIA workers (34%) compared with those who had never worked at DIA (2%). Risk factors for illness included exposure to fireproofing (OR, 4.21; 95% CI, 1.95-9.08), work in tunnels and adjoining areas (OR, 3.07; 95% CI, 1.84-5.12), length of DIA employment (OR, 0.65; 95% CI, 0.46-0.92), and preexisting bronchitis (OR, 2.43; 95% CI, 1.17-5.05). Our industrial hygiene investigation revealed alkaline dust (pH 11) present at a worksite associated with elevated risk of illness, and we identified airborne Penicillium mold widely distributed indoors at DIA. Clinical evaluation of 26 self-identified symptomatic DIA employees, including bronchoalveolar lavage and biopsy in 10, revealed work-related asthma in three workers and histologic evidence of chronic bronchitis in four who had never smoked. We concluded that future investigations of endemic work-related febrile respiratory illness among construction workers should evaluate its association with indoor exposure to dusts from alkaline fireproofing, Penicillium mold, mycotoxins, and bacterial bioaerosols.

Adult↗
PubMed1993

Laparoscopic evaluation of the argon beam coagulator. Initial report.

The objective of this study was to evaluate the safety and hemostatic properties of the argon beam coagulator (ABC) at laparoscopy. The study is composed of two parts: laparoscopic results in five anesthetized animals and a preliminary clinical trial in 35 volunteers undergoing laparoscopy. Animals were evaluated during a laparoscopic cholecystectomy training course. Private patients undergoing operative laparoscopy voluntarily consented to a hospital Investigational Review Board-approved protocol to evaluate the ABC. The pigs were 3-month-old, healthy females. The patients were healthy volunteers undergoing laparoscopy for pain, infertility or cholecystectomy. Both pigs and human volunteers underwent operative laparoscopic use of the ABC for hemostasis and selected tissue electrocoagulation using a prototype 10-mm laparoscopic probe. The safety of the ABC was evaluated in the pigs by continuously monitoring heart rate, oxygen saturation and end-tidal CO2. Patients had similar clinical monitoring during operative laparoscopy, with observation of tissue effects of the ABC for hemostasis and tissue electrocoagulation. Laparoscopic use of the ABC in animals and patients produced no observable anesthetic changes, with both pigs and patients recovering normally. The ABC allowed smokeless, hemostatic tissue electrocoagulation, with a rapid non-touching technique easy to apply laparoscopically. We conclude that the ABC can safely be used laparoscopically with excellent hemostasis and effective controlled tissue electrocoagulation. The lack of smoke and the non-touching technique for delivery allow rapid laparoscopic application. The prototype 10-mm delivery probe is cumbersome, and the argon gas flow rate of 4 L/min with firing requires constant venting of the peritoneum with close monitoring of intraperitoneal pressures.

Animals↗
PubMed1992

Gallstone lithotripsy (GSL): results of the Technomed Sonolith 3000 multicenter trials.

Gallstone lithotripsy (GSL) with the Technomed Sonolith 3000 extracorporeal lithotripter was studied in a multisite, international cooperative trial involving the United States, France, and Italy. All participating sites worked under a common protocol to investigate the safety and efficacy of GSL for symptomatic gallstone patients. These collective results are from a mix of 25 academic and community hospital sites using fixed and transportable/mobile versions of the lithotripter. As of November 1, 1990, 661 patients have been treated in this two-arm randomized study (GSL Only vs GSL + Ursodiol [Actigall]). Patients were treated with up to 2,500 shocks per session and only two treatments were allowed. All machines had standardized pressure settings (850 bar nominal) and operator adjustment of output voltage was not allowed. We saw no statistically significantly different results in initial fragmentation between patients pre-loaded with ursodiol for 2 weeks and those treated by GSL alone. Gallbladder clearance rates did vary with the stone number, size, and burden as well as the adequacy of initial fragmentation. In the GSL + Ursodiol Arm of the trial, 46.2% of patients with solitary, 5-to 20-mm calculi are stone-free at 6 months.

Adult↗
PubMed1992

[Outbreak of paratyphoid fever among Peruvian naval personnel].

A retrospective epidemiological study was conducted in connection with an outbreak of paratyphoid fever at a Peruvian naval installation in Callao. The study sought to determine the magnitude of the outbreak, the source of infection, the attack rates, the persistence of bacilli excretion, and the clinical picture of the disease. The source of Salmonella paratyphi B infection had been a meal of chicken and rice served to around 400 members of the naval police. Over a period of three weeks, 21 persons were hospitalized and 52 received outpatient treatment at the naval hospital. In addition, through a questionnaire it was revealed that 86 unreported cases of diarrhea related to the outbreak had occurred. The most common clinical manifestations were fever, headache, weakness, anorexia, abdominal pain, and diarrhea. The general attack rate was 39.8%. In a follow-up survey carried out 37 days after exposure, fecal cultures indicated that 8.5% of the persons affected continued to excrete the microorganism. The high rates of attack and transmission of S. paratyphi B in this outbreak point up the considerable pathogenicity and virulence of some strains of the microorganism and their impact on public health. It is suggested that preventive measures be taken at naval and other similar installations, including the education of workers who handle and prepare food, in order to ensure proper hygiene.

Adult↗
PubMed1991

Genetic analysis of a temporally transcribed chemotaxis gene cluster in Caulobacter crescentus.

Caulobacter crescentus performs chemotaxis by short intermittent reversals of rotation of its single polar flagellum. Tn5 insertions causing a general chemotaxis phenotype, an inability to reverse swimming direction and to form large swarm colonies, have been mapped to an 8-kb region of the C. crescentus genome. These Tn5 mutations had different effects on the methyl-accepting chemotaxis proteins (MCP), and the activities of methyltransferase and methylesterase. The Tn5 insertion mutant SC1130 had no cross-reacting MCP and had reduced levels of activity of the methyltransferase and methylesterase. Other mutants bearing Tn5 insertions retained cross-reacting MCP activity and were altered only in their methyltransferase and methylesterase activities. Using a cosmid library we isolated a clone that complemented SC1130. Complementation studies of the Tn5 mutants using derivatives of the cosmid clone showed that all the Tn5 insertions lie within a single operon that appears to encode many chemotaxis genes. The first gene in this operon was shown to encode an MCP by immuno-blot analysis of strains carrying beta-galactosidase protein fusions to portions of the operon. The promoter of this operon was located by chromosomal integration of subclones of this region and by identifying DNA fragments that were capable of expressing lacZ transcriptional fusions. The transcription of the che operon occurred at a defined time in the cell cycle, prior to cell division.

Bacterial Proteins↗