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Biomedical subjects

H S Nelson

Publications and source records attributed to H S Nelson.

At least 73 records · Page 4Linked to original sources
PubMed1994

A comparison of commercial jet nebulizers.

Seventeen commercially available jet nebulizers from 15 commercial sources were studied (Acorn-I, Acorn-II, AquaTower, AVA-NEB, Cirrhus, Dart, DeVilbiss 646, Downdraft, Fan Jet, MB-5, Misty Neb, PARI LC JET, PARI-JET, Salter 8900, Sidestream, Updraft-II, Whisper Jet). All nebulizers were filled with 2 ml of saline solution plus 0.5 ml of albuterol and powered with the same source (DeVilbiss PulmoAide). We compared total output (TO), time for total output (TTO), and percent output in respirable range (PORR). The TO was obtained by weighing before nebulization and at the point of eight-fold decline in output. The TTO was calculated from initiation of nebulization to the point of eightfold decline in output. The PORR was measured by a laser particle analyzer in continuous nebulization to the same point of abrupt drop in output. The TO varied from 0.98 To 1.86 ml (p < 0.0001) with the Acorn-I, Acorn-II, Updraft-II, and Sidestream, significantly greater than the others (p < 0.05). The TTO varied from 2.28 to 20.95 min (p < 0.0001). The AquaTower, PARI LC JET and PARI-JET, DeVilbiss, and Dart were significantly shorter than the others (p < 0.05). The PORR varied from 21.89 to 71.95 percent (p < 0.0001). The Sidestream was significantly greater than all others (p < 0.05). The PARI LC JET and PARI-JET were, in turn, significantly greater than the remaining models (p < 0.05). To combine these characteristics, we calculated respirable particle delivery rate (RPDR) by dividing TO by TTO and multiplying by PORR. The RPDR varied from 0.03 ml/min to 0.26 ml/min (p < 0.0001). The PARI LC JET (0.24 ml/min) and the PARI-JET (0.26 mg/min) had a RPDR that was significantly greater than the other models except the AquaTower, which, however, had a markedly variable performance. The Sidestream (0.19 mg/ml) did not differ significantly from the above group, nor from the DeVilbiss and Downdraft. All other models had significantly lower outputs (p < 0.05). We conclude that the output characteristics of commercial nebulizers vary greatly and will impact on the time required for treatment as well as the total amount of drug delivered to the lungs.

Aerosols↗
PubMed1994

Comparison of the bronchodilator response to albuterol administered by the OptiHaler, the AeroChamber, or by metered dose inhaler alone.

Eighteen subjects with moderate asthma participated in this double-blind study comparing the bronchodilator response to albuterol or placebo used in conjunction with three inhalation devices; the metered dose inhaler (MDI) actuator alone, the AeroChamber, and the OptiHaler. The principal comparison was the increase in FEV1 over 30 minutes. Also recorded were heart rate, time required to use each device, and patient acceptance of each device. There was a large bronchodilator response with albuterol with each of the devices, but there was no difference in the promptness or the magnitude of the bronchodilator response among the three devices. There was a small but statistically significant increase in heart rate which did not differ among devices. Subject ratings of acceptability were MDI alone best, followed by OptiHaler, then AeroChamber. We conclude (1) the bronchodilator response obtained with use of the MDI alone, the AeroChamber and OptiHaler were not significantly different; (2) patients, as a group, found the MDI required less time to use and they favored it over either spacer; (3) while in subjects employing good MDI technique, the addition of either an AeroChamber or an OptiHaler did not improve bronchodilator response. Spacers may have a role in those with poor inhaler technique or in conjunction with inhaled corticosteroids.

Adult↗
PubMed1994

Effect of RG 12525, a new leukotriene antagonist, on pulmonary function of asthmatic adults.

RG 12525 is a new oral leukotriene D4 (LTD4) antagonist with proven activity in animal and human models of leukotriene-induced bronchoconstriction. In this randomized, double-blind, parallel-group, placebo-controlled study the bronchodilator effects of single oral doses of RG 12525 of 25 and 200 mg or placebo were evaluated in 62 adult asthmatic patients. All patients had previously demonstrated 20% reversibility of FEV1 with an inhaled beta-agonist. They had an unmedicated FEV1 less than 80% of predicted value at the time of the study. Bronchodilator activity was assessed by spirometry before and at multiple time points after dosing for eight hours. A single 200-mg dose of RG 12525 of mg resulted in statistically significantly greater increases in mean maximum change above baseline for FEV1 and FEF25-75% than placebo. The peak effect was observed four to five hours after dosing. The RG 12525 dose of 25 mg dose induced better bronchodilation than placebo but the differences were not significant. Adverse clinical experiences or laboratory abnormalities were not noted.

Adolescent↗
PubMed1993

Comparative performance of five commercial prick skin test devices.

Five commercially available devices for performing prick skin testing were compared for reproducibility, patient acceptance, occurrence of false-negative skin test results, and size distribution of reactions at the negative control sites. Reproducibility of skin testing with 10 mg/ml histamine base, as expressed by coefficient of variation, was similar. However, a clear range of trauma to the skin was produced by the devices. This trauma was least with the Hollister-Stier and ALK Laboratories lancets, intermediate for the bifurcated needle by either prick or puncture, and greatest for the Multi-Test and DermaPIK devices. The more traumatic devices produced larger mean wheals and more frequent and large reactions at saline control sites, and were less acceptable to subjects. However, except for the Multi-Test device, they less often yielded false-negative responses. It is proposed that for each device a different size of wheal must be produced at the allergen site to have confidence that it exceeds the control site. The wheal size necessary for 99% specificity were as follows: Hollister-Stier lancet, 2 mm; ALK lancet, 3.0 mm; bifurcated needle prick, 4.0 mm; bifurcated needle puncture, 4.5 mm; Multi-Test device, 5.0 mm; and DermaPIK device, 5.5 mm. An additional observation was the presence of a significant gradient of reaction size on the back to both histamine and allergen (p < 0.0001), with the smallest reactions in the upper third and the largest in the lower third of the back.

False Negative Reactions↗
PubMed1993

Double-blind trial of a heated nasal aerosol in the treatment of perennial allergic rhinitis.

BACKGROUND: The effect of heated, moisturized air, delivered at 40 L/min and 43 degrees C, on allergic rhinitis was evaluated in two studies. METHODS: In the first study patients with chronic nasal symptoms and long-term exposure to a perennial allergen to which they were sensitive underwent 1 week of baseline observation and 1 week of treatment with either heated or room temperature moisturized air for 30 minutes twice daily. The effect of treatment was assessed by changes in nasal symptoms and nasal blockage index and by a global evaluation by the subjects at the end of the treatment period. In the second study subjects with a documented history of grass or weed pollen allergic rhinitis underwent titrated nasal pollen challenges immediately after treatment with either heated or room temperature moisturized air. The outcome was assessed by the end point of the nasal challenge and change in blockage index at the end point. RESULTS: In both models there was no significant difference in the response between those treated with heated and those treated with room temperature moisturized air. CONCLUSION: This study did not demonstrate any evidence of a therapeutic effect of heated, moisturized air in the treatment of allergic rhinitis.

Adult↗
PubMed1993

A double-blind, placebo-controlled evaluation of sublingual immunotherapy with standardized cat extract.

BACKGROUND: In light of the controversial status of sublingual immunotherapy in patients with allergic rhinitis, we undertook a double-blind study of this form of treatment. METHODS: Forty-one subjects with cat allergy presenting as rhinoconjunctivitis underwent 105 days of sublingual immunotherapy, with 20 subjects receiving a standardized cat extract (total dose approximately 4,500,000 allergy units) and 21 a matching placebo. Effectiveness of treatment was assessed by changes in symptoms and nasal-blockage index during 90 minutes of exposure in an apartment containing cat dander, which was performed before and after the course of treatment. Changes in cat-specific IgG and IgE levels and skin-test reactions were also monitored. RESULTS: Although there were fewer symptoms and less nasal obstruction on cat dander exposure at the end of the study the changes were not significantly different in those receiving active or placebo treatment. Specific IgG and IgE levels and prick skin test results did not change significantly during the course of the study. CONCLUSIONS: We conclude that sublingual immunotherapy with high-dose standardized cat extract was no more effective than placebo in reducing symptoms or affecting immunologic measures of cat sensitivity.

Administration, Sublingual↗
PubMed1993

Suggested approaches for research protocols involving the potential for life-threatening reactions.

These guidelines are intended to reduce the potential for serious or life-threatening reactions when clinical research is conducted. The following issues were addressed: identifying the risks involved in the research, providing adequate safeguards in the protocol design and during withholding of medication, anticipating risks, minimizing the chances for human error, providing resuscitative equipment sufficient to deal with the most serious anticipated life-threatening reactions, planning for medical support in case of a life-threatening emergency, and optimizing the use of medical personnel and expertise to handle emergency situations. The guidelines also discuss important general issues about protocol design and implementation and the human subject consent form, which should facilitate the approval of protocols by the governing institutional review board. The guidelines are not meant to be inflexible or applicable to all research situations. However, it is our hope that they will allow for clinical research to be conducted in a manner that affords the research subjects a high degree of protection from unnecessary and possibly fatal injuries.

Bronchi↗
PubMed1993

A double-blind study of troleandomycin and methylprednisolone in asthmatic subjects who require daily corticosteroids.

A group of 75 subjects with asthma requiring daily corticosteroids for control were enrolled in a 2-yr, double-blind, placebo-controlled study of the use of troleandomycin combined with methylprednisolone, compared with methylprednisolone alone, for the management of their asthma. The primary outcome variables were determination of the lowest stable methylprednisolone dose and assessment of corticosteroid side effects. Methylprednisolone dose was adjusted to maintain optimal control of asthma symptoms. A total of 30 patients receiving TAO and 27 patients receiving placebo completed 1 yr; 17 on TAO and 8 on placebo completed 2 yr of double-blind participation. Control of asthma was equivalent in both groups. The vast majority of patients in both groups achieved alternate-day dosing (29 of 30 on TAO and 23 of 27 on placebo in the first year). The lowest stable doses of methylprednisolone achieved were 10.4 mg/day (placebo) versus 6.3 mg/day (TAO) in the 1-yr group (p = 0.03). However, the baseline dose was also significantly higher in the placebo group (22.8 versus 17.6 mg/day in the TAO group). Therefore, the reductions in methylprednisolone dose were not significantly different between treatment groups. Differences were observed between the two treatment groups in serum IgG, fasting blood sugar, serum cholesterol, and progression of osteoporosis. In each instance the more unfavorable response occurred in those subjects receiving TAO. We conclude that the addition of TAO to methylprednisolone was not accompanied by a reduction in corticosteroid side effects compared with treatment with methylprednisolone alone. Furthermore, no evidence was found for a subset of "TAO responders."(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Optimal duration of nebulized albuterol therapy.

The output from a jet nebulizer was analyzed for aerosol profile, solution output, and delivery of albuterol at three different initial volume fills to determine the changes that occur during the course of nebulization. Increasing diluent volume led to significantly greater delivery of the albuterol initially placed in the nebulizer. Albuterol delivery from the nebulizer ceased completely following the onset of inconsistent nebulization (sputtering) as determined audibly and by laser particle analysis. Aerosol output rate declined by one-half within 20 s of the onset of sputtering. The albuterol concentration in the nebulizer solution increased significantly once the aerosol output declined. The weight of solution delivered as determined by change in weight of the nebulizer could not be fully accounted for as aerosol volume. It appeared that this discrepancy represented loss of water by evaporation. Aerosolization past the point of initial jet nebulizer sputtering is unproductive.

Administration, Inhalation↗
PubMed1993

Seasonal variation in immediate skin test reactions.

Seasonal variation in the size of immediate prick skin tests was examined in relation to changes in seasonal pollen exposure. Immediate skin test reactions to serial 5-fold dilutions of: (1) a specific pollen during its season (short ragweed), (2) a specific pollen from an earlier season (tree), (3) a perennial allergen (D farinae, D pteronyssinus, or cat), and (4) histamine were examined at the projected trough of ragweed-specific IgE (2nd week in July), at the peak ragweed pollen count (3rd week August), at the estimated peak in ragweed-specific IgE (4th week in September) and at a time of no pollen exposure (2nd week in February). All 30 subjects had symptoms of rhinitis during the ragweed season and a 3 mm or greater wheal to: 100,000 AU/mL of short ragweed, 1:20 wt/vol of a tree exact, and a perennial allergen either 100,000 AU/mL of cat or 10,000 AU/mL of D farinae or D pteronyssinus. The median equivalent dose (dose of skin test material required to produce the median skin test index score) for the four time periods revealed significant seasonal differences. The reactions in October and February were significantly greater than those in July and August for all skin test agents. Histamine, ragweed, and trees showed maximal sensitivity in October, while perennial allergens demonstrated a peak in skin test sensitivity during mid-February.

Adult↗
PubMed1993

Double-blind trial of pyridoxine (vitamin B6) in the treatment of steroid-dependent asthma.

Pyridoxine has been reported to largely correct an abnormality of tryptophan metabolism present in patients with bronchial asthma and to reduce the symptoms of asthma in long-term studies. We enrolled 31 patients requiring steroids (oral or inhaled) for the treatment of their asthma in a double-blind, placebo-controlled assessment of 9 weeks' treatment with pyridoxine 300 mg per day (13) or placebo (18). Outcome variables included PEFR, FEV1, asthma symptom scores, 24 hour urinary 5-HIAA, skin test reactivity to histamine and compound 48/80 and blood serotonin levels. Plasma pyridoxine levels indicated overall patient compliance with a mean change from baseline to the end of the study of 82.5 +/- 27.7 ng/mL in patients on pyridoxine and -2.9 +/- 10.3 for those on placebo (P = .0001). Furthermore, patients routinely treated with theophylline had lower (10 +/- 8 ng/mL) plasma pyridoxine levels at baseline than those not on it (19 +/- 6 ng/mL; P = .01), suggesting that theophylline may lower plasma pyridoxine levels. There was no significant difference between the pyridoxine and placebo groups in the change from baseline to the last 2 weeks of treatment phase in any of the outcome variables. We conclude that under the conditions of the study, treatment with oral pyridoxine failed to improve the outcome variables in patients requiring steroids for the treatment of their asthma. The results of this study suggest that prescription or usage of oral pyridoxine for the treatment of asthma cannot be justified in such patients.

Administration, Inhalation↗
PubMed1993

Aerosol beclomethasone dipropionate compared with theophylline as primary treatment of chronic, mild to moderately severe asthma in children.

OBJECTIVE: To compare the benefits and adverse reactions of theophylline and beclomethasone (BDP) in the long-term control of mild to moderate chronic asthma in children. DESIGN: Multicentered, double-blind, double-placebo, randomized, controlled trial. PATIENTS: One hundred ninety-five children between the ages of 6 and 16 years with mild to moderate asthma. INTERVENTION: Treatment with either BDP, 84 micrograms four times a day, or sustained-release theophylline administered twice daily in doses adjusted for optimum control of symptoms. MAIN OUTCOME MEASURES: Daily diary record of symptoms, peak flow rates, supplemental bronchodilator and glucocorticoid treatment, doctor and hospital visits, absence from work and school, and side effects. RESULTS: Aerosol BDP and sustained-release theophylline were effective primary treatments for mild to moderate chronic asthma. Beclomethasone resulted in comparable symptom control with less bronchodilator use and fewer courses of systemic steroids than did theophylline. Side effects were observed significantly more frequently with theophylline than with BDP. Growth velocity suppression was noted with BDP and was more pronounced in boys. Suppression was not associated with alterations in cortisol measurements either at baseline or following stimulation. CONCLUSION: Both theophylline and BDP are effective therapy for mild to moderate asthma. Caution must be used with the administration of BDP in children because of possible growth velocity suppression.

Adolescent↗
PubMed1992

Evaluation of in vivo breast fine needle aspirates by flow cytometry: an efficacy study.

BACKGROUND: Malignancy of the breast is frequently diagnosed through fine needle aspiration. In the hands of a skilled aspirator and cytopathologist, this can be a highly accurate procedure. PURPOSE: This study was undertaken to evaluate whether sufficient residual cells in the bore of the needle could be harvested and analyzed efficiently by flow cytometry analysis. The goal was then to determine the value of routine flow cytometry as an adjunctive technology in the interpretation of breast fine needle aspirations. METHODS: Cells were rinsed from the needles of 83 consecutive diagnostic fine needle aspirates after preliminary inspection had confirmed adequate material was obtained for cytopathology. Cells were washed, and nuclei prepared by detergent treatment. After ribonuclease treatment, DNA was stained with the fluorescent marker propidium iodide. DNA content per cell was determined by flow cytometry by measurement of right-angle fluorescence. RESULTS: Less than 4% of the samples were rejected for inadequate cell numbers. Flow cytometry criteria for evidence of malignancy included the presence of a DNA aneuploid population or an elevated rate of proliferation (13% or higher) of a diploid population. Accuracy of flow cytometry was based on cytopathologic interpretation in all cases except two which were based on results of excisional biopsy. The sensitivity of the flow cytometry analysis was 76%; the specificity was 100%, with results from flow cytometry pivotal in the correct diagnoses for two patients whose cytopathologic results were equivocal. Analysis of histograms indicated acceptable coefficients of variation for all populations. Gating analysis indicated the suitability of the material for this type of study, with an average of 85% of the events selected, or "gated in." Low recoveries were associated with the presence of necrotic debris in the sample. CONCLUSION: Flow cytometry can be a valuable adjunctive technology, capable of providing the cytopathologist with additional information regarding the character of cells analyzed.

Biopsy, Needle↗
PubMed1992

Treatment of peanut allergy with rush immunotherapy.

Peanut and peanut products are a common food in the diet. Peanuts are also one of the most common foods responsible for food-induced anaphylaxis. Patients rarely lose sensitivity to peanuts. Although the ideal treatment is avoidance, this is often not possible because of hidden exposures; therefore, a more effective treatment is needed. Subjects with confirmed peanut allergy were treated in a double-blind, placebo-controlled study with peanut immunotherapy or placebo. Objective measures of efficacy included changes in symptom score during double-blind placebo-controlled peanut challenge (DBPCPC) and titrated end point prick skin tests (PST). Three subjects treated with peanut immunotherapy completed the study. These subjects displayed a 67% to 100% decrease in symptoms induced by DBPCPC. Subjects also had a 2- to 5-log reduction in end point PST reactivity to peanut extract. One placebo-treated subject completed the study. This subject had essentially no change in DBPCPC symptom scores or PST sensitivity to peanut. Two other placebo-treated subjects underwent a second PST session. These subjects had a 1- to 2-log increase in skin test sensitivity to peanut. All peanut-treated subjects were able to reach maintenance dose, and in no case did an anaphylactic reaction occur secondary to the peanut immunotherapy. The current study provides preliminary data demonstrating the efficacy of injection therapy with peanut extract and provides a future line of clinical investigation for the treatment of this potentially lethal disease. It should be noted, however, that the rate of systemic reactions with rush immunotherapy was 13.3%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
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↗