Search PubMed⌕ Search

Biomedical subjects

H S Nelson

Publications and source records attributed to H S Nelson.

At least 109 records · Page 6Linked to original sources
PubMed1989

The effect of theophylline and enprofylline on the late cutaneous response to antigen and compound 48/80.

Theophylline and enprofylline have been demonstrated to reduce mast cell-mediator release, inhibit polymorphonuclear leukocyte activation, and have been reported to reduce the late bronchial response to antigen. The effects of theophylline and enprofylline on the late cutaneous response (LCR) to compound 48/80 and antigen were studied in 29 patients enrolled in a placebo-controlled, double-blind study of the effect of the xanthines in mild asthma. Skin testing to a common environment allergen and compound 48/80 was performed during a baseline period and in the second phase of the study after stable drug levels were achieved, at least 6 weeks later. During baseline, the mean immediate wheal diameter (IWD) with antigen was 15.7 mm +/- 0.5, resulting in 27/29 LCRs with a mean wheal diameter of 37.1 mm +/- 5.2. The mean IWD with compound 48/80 was 16.1 mm +/- 0.7, resulting in 26/29 LCRs with a mean wheal diameter of 19.6 mm +/- 2.8. Repeat skin testing during treatment revealed no statistically significant changes in the LCR elicited by antigen or 48/80 in any of the treatment groups. There was little correlation between the size of the immediate wheal produced by antigen or 48/80 and the resulting size of the late response (r = 0.174 to 0.519). However, for the same IWD, the resulting late response was smaller with 48/80 than with antigen (p = 0.003). We conclude that (1) theophylline and enprofylline have no effect on the LCR to 48/80 and antigen and (2) for equivalent immediate wheal sizes, the resulting late response is smaller with 48/80 than with antigen.

Adult↗
PubMed1989

A comparison of six epicutaneous devices in the performance of immediate hypersensitivity skin testing.

Six devices commonly used for immediate hypersensitivity epicutaneous skin testing were compared with regard to precision and diagnostic accuracy. Fifteen subjects were tested on the back to 10 mg/ml of histamine phosphate and 50% glycerosaline by prick technique with a smallpox needle (SN), bifurcated needle (BN), Greer "pen" (GP), and blood lancet, and by puncture with the Morrow-Brown needle (MB) and Multi-Test (MT). Five devices were tested in quintuplicate to histamine and once to glycerosaline in each subject; with MT, five histamine and three glycerosaline sites were used. Analysis of the wheal areas obtained with SN, BN, GP, and MB demonstrated comparable degrees of precision (coefficient of variation). The precision of MT was less than the other devices (p less than 0.05). The blood lancet demonstrated intermediate precision. Twenty-two of 45 (49%) of the glycerosaline skin tests performed with MT were falsely positive, significantly more than the other devices (p = 0.0001). We conclude that MB, BN, GP, and SP are comparable devices for use in immediate hypersensitivity skin testing. The low precision and reliability of MT used for testing on the back would appear to make this device less than adequate for diagnostic or research studies. Its high rate of false positive reactions requires caution in interpretation of results when it is used in the clinical diagnosis of allergy.

Adult↗
PubMed1989

Suppression of immediate skin tests by ranitidine.

The suppression of immediate skin reactions to histamine and compound 48/80 by ranitidine, 150 mg every 12 hours for seven doses, was determined in a double-blind study in 23 subjects. Ranitidine compared to placebo produced a 22% suppression of the wheal-and-flare response to histamine (p less than 0.05) but only a 4% suppression of the wheal and flare with compound 48/80 (not significant). Although the suppression of the histamine skin test was statistically significant, this degree of suppression may be of limited clinical significance in allergy diagnostic testing.

Adult↗
PubMed1989

Circadian variation of skin reactivity and allergy skin tests.

Previous investigations of the circadian variation in skin reactivity suggested that results of skin tests obtained in the afternoon could vary from the results obtained in the early morning and therefore could result in a differing assessment of patient sensitivity. To determine whether this was a practical concern in the normal clinical setting, we studied 20 adults and 20 children who had skin prick tests positive (3+ or more) to short ragweed. These patients were skin tested in duplicate at 8 AM and at 4 PM with fivefold serial dilutions of short ragweed extracts (1:20 to 1:12,500, wt/vol) and of histamine hydrochloride (10 to 0.016 mg/ml). Areas of wheal and flare were recorded and measured by computed planimetry. In addition, results were also read according to a conventional scoring system. Mean wheal and erythema areas with ragweed and histamine at each dilution were compared between morning and their corresponding evening values. Although there was a trend for the morning means to be larger than evening means, no significant differences between the two sessions were observed at any dilution. Mean morning skin index scores, as calculated from the combined mean wheal and erythema areas, were larger than mean evening scores for ragweed and histamine, but the differences were not of a degree to be clinically important. This observation was also true for conventional scores. Comparing the results from the two groups of children who had their first set of skin tests performed either in the morning or afternoon session indicated that there was no evidence of a refractory state of the skin during the second test sessions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Comparison of PEFR and FEV1 in patients with varying degrees of airway obstruction. Effect of modest altitude.

Measurements of FEV1 and PEFR performed on a Jones Pulmonor Spirometer (JPF) were compared with PEFR obtained with a mini-Wright peak flow meter (WPF) in 102 patients. Data were converted to percent predicted. Standard deviations of triplicate measurements were: FEV1, 3.01 percent; JPF, 7.22 percent; and WPF, 5.12 percent. Correlation of best of three measurements was FEV1-JPF r = .758; FEV1-WPF r = .744; and JPF-WPF r = .846. The mean percent predicted of the best of three values of FEV1 was 74.8 percent, JPF 91.4 percent, and WPF 94 percent. These higher values for percent predicted PEFR were obtained throughout the range of FEV1 values. Studies on nine normal volunteers in an atmospheric chamber suggested that higher altitudes may account for higher PEFR values. We conclude that PEFR, measured by either waterless spirometer or mini-Wright peak flow meter, has greater intrasubject variability than FEV1, and it tends to underestimate the degree of pulmonary impairment.

Adolescent↗
PubMed1988

Comparison of parallel line skin test assay (PLST) and ELISA inhibition (EI) methods for determination of relative potency of polymerized grass and ragweed antigenic extracts.

Relative potency estimates were performed by parallel line skin test assay (PLST) and ELISA inhibition methods for three polymerized allergen extracts (Bermuda grass, orchard grass, and a copolymer of short and giant ragweed) versus four unmodified RAST standardized reference extracts (Bermuda grass, orchard grass, and giant and short ragweed) in nine subjects. One subject experienced a systemic reaction, requiring treatment at the end of the PLST assay. Another subject had a systemic reaction during limited skin testing performed approximately 72 hours after completion of PLST. Relative potency values for the polymerized extracts obtained by PLST were much lower than those obtained by ELISA inhibition, but results were significantly (r = 0.95; p less than 0.01) correlated. Because polymerized allergen extracts are designed to be hypoallergenic, a skin test assay may underestimate their potency relative to an unmodified reference extract.

Binding, Competitive↗
PubMed1988

Recommendations for the use of residential air-cleaning devices in the treatment of allergic respiratory diseases.

In an attempt to recommend standards for room air-cleaning devices, a committee reviewed (1) the types and performance characteristics of available domestic air-cleaning devices, (2) the available data on concentrations of allergens in the indoor air, and (3) the studies that have examined the health effects of the use of indoor air-cleaning devices. Absense of adequate data on the clinical relevance of indoor ambient allergen levels, as well as the effect of air-cleaning devices on these levels, plus a general lack of health effects by these devices in published double-blind studies precluded any firm recommendations for their use. It was clear, however, that use of room air-cleaning devices in the absence of other forms of environmental control was not reasonable.

Air↗
PubMed1988

The development of subsensitivity to atropine methylnitrate. A double-blind, placebo-controlled crossover study.

This is a double-blind, placebo-controlled crossover study designed to assess the effectiveness of nebulized atropine methylnitrate (AMN) with chronic use. We studied 22 patients with asthma, 10 receiving theophylline and inhaled beta-agonists and 12 who were receiving corticosteroids as well. All had demonstrated at least a 15% change in FEV1 either spontaneously or after bronchodilator. Bronchodilator effect was measured serially for 4 h after inhalation of the initial dose and again after 2 wk of four-times-daily use. Significant bronchodilator effect was seen initially with AMN when compared to placebo (p less than 0.01). After 2 wk of use, the bronchodilator effect of AMN was significantly diminished as compared to the initial effect (p less than 0.01) but was still better than placebo (p less than 0.05). Subsensitivity did develop to varying degrees in the patients, but we were unable to identify any clinical parameters that would allow prediction of subsequent subsensitivity. We conclude that the development of subsensitivity to AMN occurs in certain patients with chronic administration but does not reflect a total loss of bronchodilator effect.

Adult↗
PubMed1987

A double-blind evaluation of skin test suppression produced by two doses of terfenadine.

For some patients, terfenadine, in the currently recommended dose of 60 mg twice daily (bid), may be only modestly effective in the treatment of allergic rhinitis. In a double-blind placebo-controlled crossover study of 12 patients, a larger dose (300 mg bid) was evaluated for its suppression of titrated skin tests to histamine and compound 48/80 to determine whether this regimen might result in greater suppression while it maintained the freedom from side effects of the presently recommended dose. In seven patients, skin test suppression by these two doses of terfenadine each administered for 3 days, was compared to that produced in an earlier study by 3 days of treatment with chlorpheniramine (8 mg three times a day). The 300 mg bid terfenadine regimen produced significantly greater skin test suppression (p less than 0.05) than the currently recommended 60 mg bid dose. There was no significant difference in side effects between the two doses, and neither active treatment regimen produced more side effects than placebo treatment. Both doses of terfenadine suppressed cutaneous reactivity significantly more than had chlorpheniramine. It is concluded that the presently recommended dose of terfenadine produces submaximal skin test suppression and that further studies are needed to investigate the clinical efficacy and safety of larger doses of terfenadine in the treatment of allergic rhinitis.

Adult↗
PubMed1987

Bile reflux gastritis.

Bile reflux gastritis is a disabling postgastrectomy condition characterized by abdominal pain, bilious vomiting, and weight loss. The syndrome appears to be caused by free enterogastric reflux of bile and other proximal small bowel constituents. Endoscopic confirmation of bile reflux and documentation of gastritis support the diagnosis but are not specific for it. Results of medical therapy with chelating agents or drugs that promote gastric motility have been disappointing. Diet and antacids frequently aggravate symptoms. The only effective treatment is surgical diversion of bile away from the gastric mucosa. During a recent seven-year period, 15 patients had diversionary operation for bile reflux gastritis diagnosed by history and endoscopic findings. Before operation, medical management had failed to yield improvement in any case. After operation, all patients showed improvement, and pain was relieved in 85%. Based on our experience, we conclude that current medical therapy may alter but not cure symptoms of bile reflux gastritis; Roux-en-Y diversion is the treatment of choice in patients with persistent symptoms; and delayed gastric emptying is a common complication after the Roux-en-Y procedure, but in our series, the incidence was reduced by using the Tanner 19 modification. New cytoprotective agents that may offer an alternative to operation are currently being studied.

Adult↗
PubMed1987

Chronic chlorpheniramine therapy: subsensitivity, drug metabolism, and compliance.

To investigate whether patients develop true subsensitivity to antihistamines during chronic therapy, we studied 14 adult subjects who received chlorpheniramine for 3-day and 3-week trials of therapy. Titrated skin tests to histamine and compound 48/80, chlorpheniramine blood levels (by HPLC), compliance, and side effects were monitored and compared during the two courses of therapy and their respective 72-hour washout periods. We found a significant correlation between chlorpheniramine blood levels and skin test suppression during both the 3-day and 3-week therapies. The 3-day chlorpheniramine therapy was more clinically effective (measured by skin test suppression corrected for serum chlorpheniramine concentration) than the 3-week therapy (P less than .01). Chlorpheniramine serum half-lives and 2-hour chlorpheniramine blood levels were not significantly different after the 3-day and 3-week trials. Compliance was significantly worse (P less than .01) during 3-week therapy. Medication side effects (particularly drowsiness) were frequently reported during both courses of therapy. We conclude that subsensitivity to chlorpheniramine does develop in adult patients receiving 3 weeks of therapy. This subsensitivity is not explained by changes in drug metabolism. In addition to subsensitivity, poor compliance may contribute to sub-therapeutic results during chronic antihistamine therapy. Side effects from antihistamines may also require individualization of therapy for certain patients.

Adult↗
PubMed1986

Addition of terbutaline to optimal theophylline therapy. Double blind crossover study in asthmatic patients.

The efficacy and side effects of oral or inhaled terbutaline were examined in 13 mild-to-moderate asthmatic patients (ages 12 to 71 years) on maintenance theophylline (levels 10 to 25 micrograms/ml). In a crossover design, each patient received for two weeks oral terbutaline, 5 mg qid, inhaled terbutaline, 400 micrograms qid, or identical placebo tablets or metered-dose inhalers. Prior to each double-blind period, terbutaline was given for two weeks to ensure development of beta-adrenergic subsensitivity. Home-monitored peak flows and need for supplementary bronchodilators were significantly improved with both oral and inhaled terbutaline, but only the inhaled drug significantly decreased symptoms. Long-term terbutaline, either oral or inhaled, added to maintenance theophylline improved the patients' pulmonary function. The inhaled drug also improved the patients' clinical status as reflected by asthma symptom scores and need for extra bronchodilator. Combining terbutaline with theophylline did not produce evidence of cardiotoxicity.

Administration, Intranasal↗
PubMed1986

Assessment of IgE-mediated sensitivity during immunotherapy: comparison of the RAST with and without adsorption of IgG to titrated prick skin tests.

The effect of specific IgG induced by allergy immunotherapy on specific IgE binding in the RAST was assessed by removal of the IgG with staphylococcus protein A bound to Sepharose. In sera from those patients with the highest titers of specific IgG, RAST binding was increased 8% following adsorption of the post-immunotherapy sera while in sera obtained from the same patients before immunotherapy adsorption increased binding only 3%. The effect of allergy immunotherapy on the titrated prick skin test was compared to the effect on the RAST to the same allergen. In nine patients who received the highest dose of grass extract, the area of the titrated prick skin tests was reduced following immunotherapy by 75%. Staphylococcus protein-A adsorption of sera from these patients drawn before immunotherapy resulted in an increase in RAST binding of 2.7% compared to an increase of 6% in sera obtained after immunotherapy, suggesting suppression of RAST binding of only 3% by specific IgG. It is concluded that RAST levels are affected less than prick skin tests by the immunologic response to allergy immunotherapy. Some interference in RAST binding is produced by specific IgG antibody in high titers, but for many critical purposes the degree of interference is not significant.

Absorption↗
PubMed1986

Cardiopulmonary effects of the pneumatic anti-shock garment on swine with diaphragmatic hernia.

The pneumatic anti-shock garment is a widely used prehospital treatment modality for injured patients in shock. Laceration of the hemidiaphragm is a post-traumatic condition that usually is unrecognized during the prehospital phase of trauma care. In order to study the effects of inflation of the pneumatic anti-shock garment on experimental swine with diaphragmatic injury, a premeasured custom-fitted external counter pressure device was applied to the swine both before and after surgically induced laceration to the left hemidiaphragm. At each inflation pressure, several measurements were recorded: blood pressure, heart rate, respiratory rate, tidal volume, pulmonary artery pressures, pulmonary capillary wedge pressure, cardiac output and arterial blood gas determinations. Roentgenograms of the chest were obtained both before and after diaphragmatic laceration and at each inflation pressure after injury. Herniation of abdominal viscera was induced in all swine at 60 millimeters of mercury and was accompanied by statistically significant aberrations in tidal volume, pH, pO2, pCO2, pulmonary capillary wedge pressure and pulmonary artery pressures. Blood pressure increased, in both the injured and noninjured swine, and remained at normal or above normal levels throughout the inflation period in both groups. Extrapolating this phenomenon to the clinical setting when the use of or further inflation of the pneumatic anti-shock garment, or both, is generally determined by blood pressure response alone, patients with blunt trauma and lacerated diaphragms in whom external counter pressure is used may sustain irreversible cerebral hypoxia before any problem is suspected.

Animals↗