Clinical Trial on Asthma - Clinical Trials Registry

Study Overview

Status

Completed

Conditions

Detailed Description

The purpose of the study is to determine the role of nitric oxide (NO) in asthma. We determine the effect of promoter polymorphisms in the gene for the NO producing enzyme, nitric oxide synthase (NOS2), on exhaled NO in healthy African Americans and Caucasians. We compare exhaled NO levels between African Americans and Caucasians. Information on race or ethnicity, serum samples, blood pressure, exhaled breath condensate and health questionnaires will be collected.

Three single nucleotide polymorphisms (SNPs) have been identified in Africans that are associated with increases in systemic NO production. These studies determine whether the NOS2 promoter SNPs are associated with differences in basal exhaled NO levels. The study of exhaled NO levels in individuals with asthma is confounded by the presence of cell types besides bronchial epithelium that produce NO, by differences in the severity of asthma and by the use of medications such as corticosteroids which alter exhaled NO levels.

Therefore, in this study exhaled NO levels in asymptomatic healthy African Americans and Caucasians are measured. The initial analysis of exhaled NO levels indicate that a subset of African American samples contained lower levels of NO than previous measurements of exhaled NO levels in Caucasians. Because differences in exhaled NO levels may influence bronchodilation and other airway responses, as part of this study, the exhaled NO levels of the African American subjects are compared to the results of sample collections from Caucasian samples.

In addition to measures of exhaled NO levels, information on race or ethnicity and DNA samples are collected to characterize samples collected from African American and Caucasian subjects. Serum samples, measures of blood pressure and exhaled breath condensate samples are collected from African Americans and Caucasians to control for confounding variables. Repeated measures of exhaled NO levels are collected to control for fluctuations in exhaled NO levels related to upper respiratory infections.

Study Type

Observational

Enrollment (Actual)

420

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

United States
- North Carolina
  - Durham, North Carolina, United States, 27710
    - Duke University Medical Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 40 years (Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

Community sample

Description

Inclusion Criteria:

Willing/able to give informed consent
self declared non-atopic, non-asthmatic
never cigarette smoker,
no significant occupational exposure to respiratory irritants or toxins,
no chronic illness
no chronic use of medications (excluding contraceptive medication),
no historical unstable cardiac or severe lung disease,
within study age parameters of 18 - 40

Exclusion Criteria:

occupational exposure to hay or grain
smoked 20 or more packs of cigarettes in a lifetime.
prior allergen immunotherapy
Allergy and or asthma
Students or employees under direct supervision by protocol investigators are ineligible
Nursing mothers
pregnancy
Other investigational medication within the last 30 days
Other medical or psychological conditions which, in the opinion of the investigator, might create undue risk to the subject or interfere with the subject's ability to comply with the protocol requirements

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
1 African American
2 Caucasian

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

National Institute of Environmental Health Sciences (NIEHS)

Collaborators

Sandler Program for Asthma Research

Investigators

Principal Investigator: Marc C Levesque, M.D., PhD, Duke University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Levesque MC, Hauswirth DW, Mervin-Blake S, Fernandez CA, Patch KB, Alexander KM, Allgood S, McNair PD, Allen AS, Sundy JS. Determinants of exhaled nitric oxide levels in healthy, nonsmoking African American adults. J Allergy Clin Immunol. 2008 Feb;121(2):396-402.e3. doi: 10.1016/j.jaci.2007.09.031. Epub 2007 Nov 26.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

May 1, 2003

Primary Completion (Actual)

June 1, 2008

Study Completion (Actual)

June 1, 2008

Study Registration Dates

First Submitted

May 2, 2008

First Submitted That Met QC Criteria