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Biomedical subjects

R W Weber

Publications and source records attributed to R W Weber.

At least 37 records · Page 2Linked to original sources
PubMed1997

Thoracoscopic management of descending necrotizing mediastinitis.

Descending necrotizing mediastinitis (DNM) is a lethal process originating from odontogenic, pharyngeal, or cervical infectious sources that descends along fascial planes into the mediastinum. Despite earlier use of antibiotics and surgical drainage, the mortality (>50%) has changed little since the first large series reported in the preantibiotic era. The surgical management remains controversial, with support ranging from cervical drainage alone to cervical drainage and routine thoracotomy. We report a case of thoracoscopic drainage and debridement of a mediastinal abscess resulting from descending necrotizing mediastinitis. The decreased morbidity of this approach compared with posterolateral thoracotomy and the improved drainage of the mediastinum compared with cervical drainage support this method as an attractive management of patients with DNM.

Abscess↗
PubMed1995

Latex allergen in respirable particulate air pollution.

OBJECTIVE: Urban air samples contain numerous irregular respirable black particles, which may be airborne tire fragments. A major component of tires is natural latex. Proteins of natural latex can act as adjuvants and as antigens capable of eliciting immediate hypersensitivity, making their presence in particulate air pollution an important clinical issue. METHODS: Particulate air pollutants were collected by volumetric sampling devices and characterized by optical microscopy, chemical solubility tests, and mass spectrometry. Extracts of rubber tire fragments were tested for elutable latex antigens by antibody inhibition assays. RESULTS: Identification of latex in air samples and milled material from automobile tires was supported by mass spectrometry results and was further confirmed by physical appearance and chemical solubility studies. Competitive immunoassay confirmed the presence of extractable latex antigens from rubber tire fragments. CONCLUSIONS: Latex antigens are extractable from rubber tire fragments, which are abundant in urban air samples. Given the adjuvant and sensitizing effects of latex, these airborne particles could contribute, through direct and indirect mechanisms, to the increase in both latex sensitization and asthma. The impact of these particles should be considered in the issue of morbidity and mortality rates associated with respiratory diseases and air pollution.

Air Pollutants↗
PubMed1995

The prevalence of Dermatophagoides mite allergen in Colorado homes utilizing central evaporative coolers.

OBJECTIVE: The prevalence of mite allergen was studied in homes in which the indoor relative humidity may be increased by use of an evaporative cooler. METHODS: Colorado homes in which central evaporative coolers are used and control homes were evaluated. ELISAs with monoclonal antibodies specific for Der p 1 and Der f 1 were performed on dust samples from each home in May and August. Indoor relative humidity and temperatures were recorded daily. RESULTS: May samples did not show significant levels of mite allergen ( < 2 micrograms/gm dust). Of the August samples, 48 of 95 samples from homes with evaporative coolers (50.5%) had levels of Der p 1 and Der f 1 of 2 micrograms/gm dust or greater, but only 5 of 95 control samples (5.2%) had levels of 2 micrograms/gm dust or greater (p < 0.00001). Twelve of 19 homes with evaporative coolers (63%) were positive for mite allergen. Five of 19 (26%) control homes were positive (p < 0.05). The homes with evaporative coolers had average indoor relative humidity of 51% or greater: control homes had average relative humidity of less than 45%. CONCLUSION: Altering the indoor environment by raising indoor relative humidity through use of evaporative coolers leads to conditions that may facilitate Dermatophagoides survival.

Animals↗
PubMed1995

Analysis of meteorologic variables and seasonal aeroallergen pollen counts in Denver, Colorado.

BACKGROUND: The observation of low levels of weed pollens following a freeze and an early autumn snowfall in Denver, Colorado led to this analysis of meteorologic variables and pollen counts. OBJECTIVE: The purpose of this study was to examine, in depth, the relationship between observed pollen counts and a selection of independent meteorologic variables. METHODS: We prospectively studied in 1991 daily high and low temperature, relative humidity, precipitation, barometric pressure, percent sunshine, wind velocity and direction, tree, grass, and weed pollen, as well as dates of the first frost/freeze. Similar data were retrospectively analyzed for 1987-1990. RESULTS: Correlation coefficients for the prospective data were as high as .611 for high temperature and cottonwood and .718 for high temperature and maple (P < .001). High and low temperature showed strong correlations with the combined weed counts (.598 and .628, respectively, P < .001). CONCLUSIONS: Denver weed pollens appear impacted more by temperature and less by precipitation and humidity, while the converse is true for tree and grass pollen. However, weed pollen, especially sage, may appreciably rebound after freezing temperatures. While separate meteorologic variables may have high correlations with specific pollen counts in a given year, such effect is not consistent and varies from year to year.

Allergens↗
PubMed1994

The role of methotrexate in the management of steroid-dependent asthma.

Severe asthma often requires high-dose corticosteroid therapy. However, steroid therapy is fraught with many side effects. There are conflicting reports in the literature regarding the role of methotrexate in reducing the steroid requirements of these patients. This study examined the role of low-dose methotrexate in the management of steroid-dependent asthma. Eleven subjects with stable steroid-dependent asthma were enrolled in a placebo-controlled double-blind crossover trial. Patients received methotrexate, 15 mg/wk, or placebo each for two 12-week periods. There was significant improvement of pulmonary function and reduction of prednisone requirement in both placebo and methotrexate treatment periods. However, methotrexate was not superior to placebo. Only 3 of 11 patients responded to methotrexate. Although low-dose methotrexate therapy may have a role in a small select group of steroid-dependent asthmatics, it provided no additional benefit overall.

Adolescent↗
PubMed1993

Food additives and allergy.

There is ample evidence that food additives of several sorts may precipitate adverse reactions. Some of these have catastrophic potential such as sulfite sensitivity in asthmatic patients. Fortunately, asthmatic responses to a variety of additives are certainly not as prevalent as once feared, and are probably unusual. Restricted diets are of no general benefit in asthmatic patients. In contrast to asthma, urticarial or other cutaneous reactions to food additives are more common. A restricted diet for a few months' duration may be beneficial, although the mechanism through which this is achieved is unclear. Suspected food additive sensitivities are best documented by oral challenges, preferably in a double-blind manner. Challenges in asthmatic patients need to be done with patients continuing on their routine medications to avoid false positives. All care should be taken to titrate the doses and schedule the doses appropriately, since several of these agents could provoke large drops in pulmonary function. With urticarial patients, an adequate baseline of urticarial activity needs to be established before the challenges so that fluctuations in normal activity are not construed as a positive result. Despite a large number of studies evaluating the role of food additives in hyperkinesis, results are not uniform. Evidence does suggest that there is a small subset of primarily younger children in whom additives will impact on behavior. As with asthma and additives, the problem appears to be much smaller than originally postulated.

Food Additives↗
PubMed1992

Use of standardized and conventional allergen extracts in prick skin testing.

This study examined whether commercially available conventional and standardized allergen extracts differ enough in potency to affect routine prick skin test results. Extracts of white oak, timothy, Bermuda, Russian thistle, short ragweed, sagebrush, Alternaria, and cat dander were examined in allergic patients and in nonatopic subjects with no personal or family history of asthma, rhinitis, or eczema. Conventional nonstandardized extracts (1:10 or 1:20 wt/vol) from two sources were compared with three concentrations (100,000, 10,000, and 1000 AU/ml) of a single standardized extract. Preparations were compared in the allergic patients with computerized planimetry, and in all patients and subjects with a conventional skin test grading system. Skin test area for the conventional extracts generally fell between the 10,000 and 100,000 AU/ml concentrations of the standardized extract. Skin test reactivity to at least one allergen extract occurred in 31% of the nonatopic subjects; there was no difference between the number of 3+ and 4+ reactions for conventional and standardized extracts. Results indicate that standardized and conventional extracts are frequently similar, but are not directly interchangeable.

Adolescent↗
PubMed1992

Aerobiology of the Colorado Rockies: pollen count comparisons between Vail and Denver, Colorado.

Pollen patterns were compared between Vail, CO (8,200 feet elevation), Aspen, CO (7,900 feet) and Denver, CO (5,280 feet) from 1984 through 1988. Counts were obtained at all sites with a volumetric intermittent cycling rotating impaction sampler. Aspen and Denver were compared in 1984, and Vail and Denver from 1985 through 1988. While counts were generally lower in the mountain sites than Denver, certain pollens, especially trees, were quite high. Ragweed was essentially absent from Aspen and Vail, and chenopod-amaranth counts were very low. Cedar, pine, and aspen frequently pollinated despite active snowfall.

Air Pollution↗
PubMed1991

Methotrexate in the treatment of steroid-dependent asthma.

A double-blind, placebo-controlled, crossover study was designed to compare steroid requirements between placebo and methotrexate (MTX) treatment in subjects with corticosteroid-requiring asthma. Subjects began with a steroid taper and then were randomized to a 3-month trial of drug or placebo therapy. Subjects received 15 mg of MTX a week or identical placebo. A 1-month washout period was completed before the crossover trial. Symptom scores, peak flow rates, spirometry, and beta-agonist frequency were closely monitored. Ten subjects completed the study. The average dose of prednisone during the placebo-treatment period was 11.97 mg/day compared to 8.37 mg/day while subjects were taking MTX. This was a 30% reduction in daily steroid requirement (p less than 0.01). Symptom scores and spirometry did not differ between the crossover trials, and overall clinical status was not altered. Complications from MTX were mild and included anorexia, alopecia, and stomatitis. All complications resolved with dose reduction or when MTX was stopped at the end of the study. No subjects withdrew from the study because of MTX complications. Low-dose MTX significantly reduced the steroid requirement in this group of subjects with steroid-dependent asthma. This reduction in steroid requirement was obtained without altering clinical status and without significant complication.

Adolescent↗
PubMed1991

Occupational asthma and rhinoconjunctivitis from inhalation of crystalline bovine serum albumin powder.

A 24-year-old white female laboratory technician developed recurrent rhinoconjunctivitis and wheezing immediately following repeated exposure to purified lyophilized bovine serum albumin (BSA). Prick and titrated intradermal skin tests revealed strongly positive results in the patient and negative results in normal controls. A titrated double-blind, placebo-controlled bronchial inhalation challenge with an aqueous BSA solution was positive at 10 mg/mL. Use of an albuterol metered dose inhaler and avoidance of laboratory exposure to BSA have resulted in resolution of symptoms. These results are consistent with an IgE-mediated mechanism, and this case represents the first reported instance of occupational asthma and rhinoconjunctivitis to inhaled BSA powder.

Administration, Inhalation↗
PubMed1990

Chronic urticaria exacerbated by the antioxidant food preservatives, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT).

Two patients with chronic idiopathic urticaria in whom remissions were achieved with dye- and preservative-elimination diet had exacerbations of their urticaria when they were challenged under double-blind, placebo-controlled conditions with butylated hydroxyanisole and butylated hydroxytoluene. After elimination of butylated hydroxyanisole and butylated hydroxytoluene from their diets, there was marked abatement of the frequency, severity, and duration of their urticaria. These antioxidants appear capable of aggravating symptoms in certain patients with chronic urticaria.

Acetaminophen↗
PubMed1989

Hypereosinophilia, neurologic, and gastrointestinal symptoms after bee-pollen ingestion.

A patient developed hypereosinophilia (13,440 cells per cubic millimeter) 6 weeks after beginning the ingestion of bee pollen. Symptoms included generalized malaise, headache, nausea, abdominal pain diarrhea, generalized pruritus, and decreased memory. Evaluation revealed no other known cause for the patient's hypereosinophilia, which resolved after bee-pollen ingestion was stopped. The product contained a mixture of entomophilous and anemophilous pollens to which the patient was skin test positive. An open challenge with the bee pollen later reproduced the presenting symptoms with a concomitant rise of the eosinophil count from 207 to 890 cells per cubic millimeter. The patient has since remained well avoiding bee pollen. This study strongly suggests that hypereosinophilia with attendant pathophysiologic disturbances may be an adverse reaction to bee-pollen ingestion in atopic individuals.

Adult↗
PubMed1989

Evaluation of nasal patency by fiberoptic rhinoscopy.

A novel method of assessing anterior nasal patency by flexible fiberoptic rhinoscopy was evaluated in two centers by comparison with active anterior rhinomanometry. Rhinoscopy and rhinomanometry were performed 20 times on each of 14 subjects during 14 to 26 minutes. The procedure was videotaped, and nasal airway area was measured from a video monitor. The mean coefficients of variation for rhinoscopy and rhinomanometry were 14% and 19%, respectively. Another investigator examined five subjects by rhinoscopy 30 times in 15 minutes; the mean coefficient of variation was 9%. These means were not significantly different. Rhinoscopy and rhinomanometry were performed at 30-minute intervals for a 6-hour period in 13 subjects. Three investigators independently evaluated results for changes in nasal function characteristic of the nasal cycle. Rhinoscopy detected the nasal cycle in an average of 72% of subjects and rhinomanometry in 49%. Both methods detected the response to topically applied oxymetazoline and methacholine. Results indicate that, whereas the two procedures evaluate different aspects of nasal function, their precision is similar. Rhinoscopy additionally permits evaluation of nasal mucosal changes occurring from disease or treatment.

Airway Resistance↗