Exploring the Mechanisms of Indoxyl Sulfate Production by Oral Tryptophan Challenge Test

December 8, 2019 updated by: Ting-Yun Lin, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation
Cardiovascular disease (CVD) is prevalent in patients with chronic kidney disease (CKD) and is associated with extremely poor prognosis. Traditional risk factors for the general population, such as diabetes mellitus, high blood pressure, and dyslipidemia, are more common in patients with CKD but cannot fully explain the increased risk of this population. New evidence suggests that the uremic milieu itself plays a critical role in the development and progression of CVD. The gut microbiota is markedly altered in CKD, with overgrowth of bacteria that produce uremic toxins. Indoxyl sulfate (IS) is among the most representative gut-derived uremic toxins and has been most frequently implicated as a contributor to the pathogenesis of CVD in CKD. IS is converted from indole, a gut bacteria metabolite of dietary tryptophan, by two hepatic enzymes, CYP2E1 and SULT1A1. The majority of studies have assessed IS toxicity in cultured cells and animal models. However, human data have been conflicting and the benefit of using orally administered adsorbents to reduce IS levels in unselected CKD patients was not supported by results from the recent randomized controlled trials. IS levels may fluctuate widely from time to time with dietary intakes. The investigators hypothesize that a postprandial IS concentration may more reflect its toxicity than a single time point (fasting or predialysis IS) concentration measured in clinical studies. Therefore, the investigators plan to establish an oral tryptophan challenge test (OTCT) by using an oral loading of 2 gm tryptophan to simulate the postprandial increase of plasma IS. The investigators will recruit 60 healthy volunteers to undergo OTCT. A pharmacokinetic study of IS after the OTCT will be performed in 20 of them to verify and simplify the design of OTCT protocol. The results of OTCT will be integrated with whole metagenome analysis of fecal microbiota and genetic polymorphism analysis of CYP2E1 and SULT1A1 to explore the mechanisms of IS production. In addition to the known genes in microbe produces indoles, other supporting bacteria or genes will be examined by using metagenomic shotgun sequencing data.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
42

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

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

  • Taiwan
      • New Taipei City, Taiwan, 231
        • Taipei Tzu Chi Hospital

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

20 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • (1) age older than 20 years
  • (2) no exposure to antibiotics or probiotics within the 3 months before entering the study.

Exclusion Criteria:

  • (1) recent gastrointestinal discomfort (such as nausea, vomiting, abdominal pain, constipation, or diarrhea) or
  • (2) a history of chronic diseases including diabetes mellites, hypertension, CVD, CKD, liver disease, malignancy, and autoimmune disease.
  • (3) pregnancy or breast feeding
  • (4) currently use of antipsychotics, Hypnotics, Demerol, Dextromethorphan, tramadol, pentazocine

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

  • Primary Purpose: Basic Science
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Tryptophan loading
All participants are introduced to receive tryptophan loading test.
Dietary supplement: Doctor's Best L-Tryptophan
2g tryptophan loading once

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Indoxyl sulfate
Time Frame: the area under curve of serum and urine indoxyl sulfate within 72 hours
serum and urine indoxyl sulfate concentration measurement
the area under curve of serum and urine indoxyl sulfate within 72 hours

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Indole-3-acetic acid
Time Frame: the area under curve of serum and urine Indole-3-acetic acid within 72 hours
serum and urine Indole-3-acetic acid concentration measurement
the area under curve of serum and urine Indole-3-acetic acid within 72 hours

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Ting-Yun Lin, MD., Taichung Tzu Chi Hospital

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 (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
October 1, 2019

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
November 30, 2019

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
November 30, 2019

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
September 29, 2019

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 3, 2019

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 7, 2019

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
December 10, 2019

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 8, 2019

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
December 1, 2019

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 08-P-055

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

No

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Cookie Settings

We use cookies to ensure that we give you the best experience on our website. For more details carefully read our Privacy and Cookies Policy. ...>>>You can change your preferences or withdraw your consent at any time by deleting the cookies from your website or computer as described in the policy. Please accept it and choose your preferences by ticking the corresponding boxes in the "Manage Settings" section below. Please carefully read our Terms of Service before you proceed with using any part of this website.
«Manage Settings