Clinical Research Directory

A Study of SI-B001+SI-B003 Combined With Platinum-based Chemotherapy as First-line Treatment in Patients With Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma

This study is a open, multi-center phase II clinical study to explore the efficacy, safety and pharmacokinetic/pharmacodynamic characteristics of SI-B001+SI-B003 combined with platinum-based chemotherapy as first-line treatment in patients with recurrent or metastatic head and neck squamous cell carcinoma.

Efficacy of Topical Insulin Gel as a Coupling Medium in Phonophoresis-Assisted Physiotherapy vs Liposomal Insulin in Management of Joint Inflammation

Although most clinical applications of topical insulin have centered on diabetic wound healing, emerging evidence in animal models supports its use in musculoskeletal inflammation. In osteoarthritic models, insulin was shown to downregulate cartilage-degrading enzymes (MMP-1, MMP-13, ADAMTS4) in synovial fibroblasts by activating the insulin receptor and PI3K/Akt signaling pathways, indicating direct synovial anti-inflammatory effects3. From a physiotherapeutic perspective, therapeutic ultrasound facilitates deeper tissue heating and enhances local circulation, potentially improving the dermal and transdermal absorption of topically applied agents. Therefore, using insulin in gel form as a coupling medium offers dual benefits: enhanced drug delivery via ultrasound and localized modulation of inflammatory processes in joints and soft tissues. This synergy could lead to superior pain relief and functional recovery compared to standard ultrasound gel. * Primary Objective: To evaluate the effect of topical nano-insulin gel on pain reduction and functional improvement compared to standard insulin gel combined with the Phonophoresis technique. * Secondary Objectives: To assess quality of life markers as changes in joint mobility, strength, and incidence of local/systemic adverse effects.

Spectroscopic Assessment of Myocardial Oxygenation Changes in Pediatric Heart Surgery

The goal of this observational study is to investigate the ability of the SpectroCor Tissue Oxygenation Monitor and its accessory SpectroCor Sensor to observe and monitor changes in cardiac oxygen availability in pediatric patients during open-heart surgery. Patients of less than 18 years old who, and whose guardian(s), when applicable according to national legislation, have signed the informed consent, can participate in the study. The primary hypothesis is that the SpectroCor Tissue Oxygenation Monitor and its accessory SpectroCor Sensor can detect myocardial oxygen availability in pediatric open-heart surgery patients. It is expected that the detected tissue oxygenation timely correlates with procedures affecting myocardial perfusion and other clinical parameters during the operation. The secondary hypothesis is that the SpectroCor Tissue Oxygenation Monitor and its accessory, the SpectroCor Sensor, are safe to use, and their usability is acceptable. No comparison group is included in the study. The devices are used by the study investigators during open-heart surgery to collect myocardial tissue spectrometer data from the pediatric population to validate and potentially further develop the monitor and its accessory, the sterile sensor. The follow-up period for each participant ends with discharge from the hospital. No data (such as questionnaires) are obtained directly from the study participants.

Berberol P for Mild-to-Moderate Hypercholesterolaemia

This randomized, controlled, multicentre clinical trial will evaluate the efficacy and safety of Berberol® P compared with Berberol® K in adults with mild-to-moderate hypercholesterolaemia. A total of 255 participants will be randomized in a 1:1:1 ratio to receive Berberol® P 1 tablet daily, Berberol® P 2 tablets daily, or Berberol® K 1 tablet daily for 12 weeks. The study will primarily assess whether Berberol® P is non-inferior to Berberol® K in reducing low-density lipoprotein cholesterol (LDL-C). Changes in other lipid parameters, glucose metabolism, anthropometric measures, blood pressure, and safety will also be evaluated.

Fluoroethyltyrosine for the Evaluation of Intracranial Neoplasm

This is a single center study investigating the use of Fluoroethyltyrosine (FET) in the detection of brain tumors. FET accumulates in malignant cells within intracranial neoplasms and can be used to detect recurrent disease and characterize grade of glial neoplasms.

Cognitive Neuroscience of Autism Spectrum Disorders

Background: * Autism spectrum disorders (ASDs) are a group of developmental disorders that affect communication, social interaction, and behavior. Relatively little is known about the relationship between genetics and behavior among these individuals and their close relatives. Researchers are interested in using interviews and rating scales to better understand these issues, as well as collecting brain scan data and genetic samples for testing and comparison. * By comparing test results and genetic samples from healthy volunteers, people with ASD, and parents (or caregivers or legal guardians) of the first two groups, researchers hope to better understand the neuroscience of ASD. Objectives: * To learn more about the brain in healthy people and in people with autism spectrum disorders. * To study genes that might be involved in autism spectrum disorders by collecting DNA samples from participants. Eligibility: The following groups of participants will be eligible for the study: * Individuals between 5 and 89 years of age who have autism spectrum disorders. * Healthy volunteers between 5 and 89 years of age. * Cognitively impaired children between 5 and 17 years of age. * Parents/caregivers/legal guardians of individuals in the above three groups. Design: * Participants will visit the National Institutes of Health Clinical Center for research tests, which will be administered over multiple visits. Researchers will determine the specific tests to be administered based on the medical history of the study participant. * Researchers will study the brain through interviews, tests of thinking and memory (neuropsychological tests), brain imaging with magnetic resonance imaging (MRI), and magnetoencephalography (MEG). * The study will also collect blood or saliva to obtain a DNA sample.

Bilateral Monofocal Versus Monofocal-EDOF IOL Implantation: Quality of Vision Comparison

The goal of this clinical trial is to compare visual quality after cataract surgery between two groups: bilateral monofocal intraocular lenses (IOL) and monofocal and contralateral extended depth-of-focus (EDOF) IOL implantation. The main question it aims to answer is: • does the combination of both monofocal and EDOF IOLs presents an advantage over bilateral monofocal IOL implantation in the daily life of patients undergoing cataract surgery without the disadvantages of bilateral EDOF IOL implantation? Participants will: * be randomised in either bilateral monofocal group or monofocal and EDOF group * undergo visual acuity testing with and without correction at all distances * be asked to complete a quality of vision questionnaire * undergo non-invasive examinations to measure residual astigmatism, contrast sensitivity, straylight, optical aberrations, reading spead.

Data Collection, Clinical Care and Interventions in CCR, NCI

This study provides cancer care through the National Cancer Institute's Medical Oncology Branch (MOB) to patients who are not enrolled in an active treatment research protocol. Patients receive standard treatments only; no investigational therapies are provided on this protocol. Patients 18 years of age and older may be eligible for this protocol. Candidates are patients for whom an NCI investigator decides that the interests of the patient and the NCI are best served by the patient's enrollment in this protocol to receive care and follow-up within the MOB. This includes patients in the following categories: * Patients previously enrolled in NCI trials whose participation in this protocol may continue to provide researchers important scientific information * Patients who will be eligible for a research protocol within the foreseeable future * Patients whose medical welfare will be seriously compromised by referral back to the community, such as patients with a rare or complex disease for which community resources are inadequate or unavailable * Terminally ill patients who have received most of their specialized medical care at the Clinical Center and for whom humanitarian considerations dictate that they continue to receive their medical care at NIH after going off study for the remaining weeks or months of life * Patients with cancer or HIV, or people at risk for cancer or HIV for whom cancer treatments at the NCI are requested through the MOB consult service * Patients who are participating in a non-treatment NCI research protocol and require standard-of-care therapy * Patients with cancer or HIV or people at risk for cancer for whom cancer treatment or management at the NCI would add significant value to the institute's cancer training program Participants receive standard medical care, including periodic routine laboratory tests, diagnostic x-rays, and nuclear medicine scans to monitor the course of illness and the effects of any treatment. ...

Home-Based Functional Electrical Stimulation for Lower Limb Rehabilitation in Stroke Patients.

This assessor-blinded, randomized, parallel-group feasibility trial will evaluate the feasibility and preliminary effectiveness of a home-based Functional Electrical Stimulation (FES) system for lower-limb rehabilitation in adults recovering from stroke. The study will be conducted at two sites within the INSTRUCT Network in India. Adults aged 18 years or older who are 1 month to 1 year post-stroke and have mild to moderate lower-limb weakness will be eligible to participate. A total of 70 participants will be randomly allocated in a 1:1 ratio to either a home-based FES intervention group or a control group receiving standard rehabilitation. Participants in the FES group will receive training on safe and independent use of the FES device before commencing home treatment. FES will be delivered to selected lower-limb muscles, including the quadriceps, tibialis anterior, and hamstrings, for 30 minutes per session, 5 sessions per week, for 12 weeks. The intervention will be supported by a smartphone-based telerehabilitation platform that will provide remote clinician support, training, adherence monitoring, and troubleshooting. The FES system is being developed with IoT-enabled monitoring and ECG-based heart-rate safety monitoring to facilitate safe home use. Participants in the control group will receive standard outpatient care and home-based rehabilitation without FES. Both groups will receive equivalent remote clinician contact and education. The primary purpose of the study is to determine the feasibility of home-based FES, including recruitment, retention, adherence to prescribed treatment sessions, safety, and participants' ability to independently operate the device at home. Secondary evaluation will assess preliminary changes in functional walking ability using the 6-Minute Walk Test (6MWT), measured at baseline and after 12 weeks. The study is intended to generate feasibility and preliminary effectiveness data to inform the design of a future, adequately powered randomized controlled trial and to assess the potential for wider implementation of home-based FES rehabilitation for people recovering from stroke.

Predicting Weight Gain and Weight Loss Associated With Overeating or Fasting

This study will investigate how to better predict why some individuals gain or lose weight more easily than others. It will examine whether the increase in the amount of energy a body burns in 24 hours with overeating or the decrease over 24 hours with fasting can help determine how easily someone gains or loses weight. Healthy people between 18 and 60 years of age who have a body mass index (BMI) between 18.5 kg/m(2) and 24 kg/m(2) (for overfeeding study) or a BMI greater than 27 kg/m(2) with a body weight less than 350 pounds (weight loss study) may be eligible for this study. The study requires a 10-week admission to the NIH Clinical Center (2-week baseline, 6-week overfeeding/weight loss, 2-week post-weight change). Participants undergo the following tests and procedures during the hospital admission: * Medical history, physical examination and laboratory studies * Questionnaires to assess eating behavior, food preferences, body composition, and activity level * Body composition assessment (height, weight, waist circumference, and fat mass and muscle content through DXA and MRI scans) * Oral glucose tolerance test * Meal test to measure the response of certain hormones to food * Activity monitors to determine activity level * Metabolic chamber study to measure calories burned over 24 hours and monitor body temperature * Free-living energy use study to measure calories burned under normal home conditions over 7 days * Fat and muscle biopsies * Dietary intervention: Measurements of food intake and energy loss over a 6-week overfeeding (1.5 times the subject s normal food intake) or weight loss (one-half the subject s normal food intake) program Followup procedures after the inpatient stay: * Height and weight measurements at 6 months (overfeeding study participants) and monthly for the first year, at 3-month intervals for the second year, and then yearly for 3 more years (weight loss study participants) * Yearly visits (2-night inpatient stay) for all participants for repeat meal test, DXA, oral glucose tolerance test, behavioral questionnaires and, in women who can become pregnant, pregnancy test

To Evaluate the Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Immunogenicity of LYNC-101 for Injection in Healthy Adult Participants

This Phase I study is designed to evaluate the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), immunogenicity, and cytokine profiles of LYNC-101 for Injection in healthy adult participants. The study consists of 2 parts: Part 1 is a single ascending dose (SAD) study and Part 2 is a multiple ascending dose (MAD) study. In Part 1, participants will receive a single intravenous infusion of LYNC-101 for Injection or placebo across sequential ascending dose cohorts. In Part 2, participants will receive intravenous infusions of LYNC-101 for Injection or placebo once every 3 weeks for a total of 3 doses across sequential ascending dose cohorts.

A Study About the Safety of a Single ASP2020 Eye Injection and if it Helps People With Vision Loss From Stargardt-type Eye Conditions

Macular dystrophies are a group of inherited eye conditions that affect the macula. The macula is in the center of the retina, the light sensitive part at the back of the eye. In people with macular dystrophies, some of the cells in the macula gradually stop working and may die over time. This leads to loss of central vision, which can make it harder to read, recognize faces or see fine details. What's seen out of the corner of the eye (peripheral vision) is mostly unaffected. Stargardt disease (STGD) is a type of macular dystrophy which is caused by 1 faulty gene (ABCA4). Vision loss most typically begins in childhood or teenage years but may also develop in adulthood. As well as STGD, there are other macular dystrophies that look very similar to STGD and are called STGD-like macular dystrophies. These are caused by many other different genes. Together, STGD and STGD-like conditions can be called STGD-type macular dystrophies. This is an early development study of ASP2020 in adults, teenagers, and children with STGD-type macular dystrophies. ASP2020 are human stem cells which have been changed into cells found in the macula. In this study ASP2020 will be given to people for the first time. The main aim of the study is to check the safety of ASP2020 and how well people tolerate it. Other aims are to learn if people have an immune reaction to ASP2020, and if there are signs that the stem cells replace damaged cells in the retina, and vision improves for people with STGD-type macular dystrophies. ASP2020 will be given as a single injection into the eye, under the retina. This requires a surgical procedure where the person is put to sleep by a general anesthetic. At the end of surgery, a steroid will be injected into the eye to reduce any swelling. The study has 2 parts. In Part 1, different small groups will receive a lower to higher dose of ASP2020. This is done to find a suitable dose to use in Part 2. The adults will receive the lower dose and higher dose before the teenagers. There will be a 6-month gap between the last adult receiving the lower dose of ASP2020 and the first teenager receiving the same lower dose. This will also happen for the last adult receiving the higher dose of ASP2020 and the first teenager receiving the higher dose of ASP2020. Any medical problems will be recorded for each dose in each group. Children will not receive ASP2020 in Part 1. In Part 2, different groups of adults, teenagers and children will receive the most suitable dose of ASP2020 worked out from Part 1. People will be in the study for about 1 year and they will visit the clinic several times. In both parts of the study, safety checks will be done at each visit, and the study doctors will continue to check for any medical problems throughout the study. Various eye tests and eye imaging will be done throughout the study. Blood tests will also be done at some of the visits during the study.

Performance and Safety of LightForce® Therapy Lasers on Shoulder Soft Tissue Inflammation Pain Reduction

DJO UK Ltd (ENOVIS) is conducting this study to assess the effectiveness of LightForce® Therapy Lasers on pain reduction in shoulder soft tissue inflammation. In detail this study will assess superiority of LightForce® Therapy Lasers combined with standard of care, represented by physiotherapy/exercise program compared to sham laser combined with standard of care (physiotherapy/exercise program) on pain reduction in subjects with shoulder soft tissue inflammation due to Impingement (Subacromial impingement syndrome (SAIS)) or Rotator Cuff Tendinopathy (RCT),. In addition, this study allows to collect post market clinical data on the safety and performance of LightForce® Therapy Lasers, when used, following the normal clinical practice, in accordance with its approved and CE marked intended use.

Sleep Efficacy Randomized Evaluation of a Novel Digital Therapeutic for Insomnia

This study is a multicenter, randomized, double-blind, sham-controlled clinical investigation designed to evaluate the effectiveness and safety of BELL-001, a digital therapeutic developed to improve symptoms of insomnia. Insomnia is a common sleep disorder that can significantly affect daytime functioning, mood, and overall quality of life. Many patients continue to have difficulties despite lifestyle changes or medication, and safer, non-pharmacological treatment options are increasingly needed. BELL-001 is a smartphone-based therapeutic that delivers personalized auditory stimulation during the pre-sleep period. The device is intended to promote relaxation and support the transition into sleep by analyzing individual breathing patterns and providing synchronized sound feedback. The study will compare BELL-001 with a sham (placebo-like) digital device that looks identical but does not provide the active therapeutic functions. Adults diagnosed with insomnia will be randomly assigned to either the BELL-001 group or the sham group. Participants will use the assigned device for four weeks. Throughout the study, sleep-related symptoms, daytime functioning, fatigue, and quality-of-life measures will be assessed. The primary outcome is the change in Insomnia Severity Index (ISI) scores after four weeks of treatment. Safety will be monitored regularly through participant reports and clinical evaluations. This trial is being conducted at multiple hospitals in Korea and follows ethical guidelines, including review and approval by institutional review boards (IRBs). Participation is voluntary, and all individuals will provide informed consent before any study procedures begin. The results of this study are expected to provide key evidence for the clinical use of a digital, non-pharmacological intervention for adults with insomnia.

Wound Healing After Gingivectomy

Gingival enlargement caused by chronic inflammation may require surgical intervention when non-surgical periodontal therapy is insufficient. Gingivectomy and gingivoplasty are commonly performed procedures to remove excessive gingival tissue and restore normal gingival contour. However, postoperative wound healing may be affected by factors such as microbial contamination and the inflammatory response. Medical ozone therapy has antimicrobial, anti-inflammatory, and biostimulatory properties that may enhance tissue regeneration and accelerate wound healing. The aim of this randomized split-mouth clinical trial is to evaluate the effect of adjunctive gaseous ozone therapy on wound healing following gingivectomy/gingivoplasty in individuals with chronic inflammatory gingival enlargement. Twenty-four systemically healthy participants diagnosed with chronic inflammatory gingival enlargement will be included. Surgical sites will be randomly assigned in a split-mouth design to either the test group (gingivectomy/gingivoplasty with adjunctive gaseous ozone application) or the control group (gingivectomy/gingivoplasty alone). Clinical periodontal parameters (Plaque Index, Gingival Index, Bleeding on Probing, Probing Pocket Depth, and Clinical Attachment Level) will be assessed at baseline and post-operative Day 21. Histopathological outcomes (Superficial Cell Index and Keratinization Index) will be evaluated at baseline and on post-operative Days 1, 3, 7, and 21. The results of this study are expected to provide clinical and histopathological evidence regarding the potential benefits of adjunctive ozone therapy in periodontal wound healing.

Effect of Utilizing Virtual Reality With Pulmonary Rehabilitation on Depression in COPD Patients

The goal of this study is to find the effect of utilizing virtual reality with pulmonary rehabilitation on depression in COPD patients. The main question it aims to answer is: Does utilizing virtual reality with pulmonary rehabilitation reduce depression in COPD patients?

Effects of Meal Macronutrients on Postprandial Lipids

Background: Abnormal fats in the blood can lead to many problems, including heart disease. Researchers want to learn more about how eating meals with different levels of nutrients affects fats in the blood. Specifically, they want to study people with too much body fat, too little body fat, and a kidney problem called nephrotic syndrome. Objective: To learn more about how different types of foods affect fat levels in the blood. Eligibility: People aged 18 years or older with a health condition that affects how their body handles fats. Healthy volunteers are also needed. Design: Participants will have 2 overnight stays in the clinic within 6 months. At each visit, after staying overnight, they will eat a breakfast casserole. At 1 visit, breakfast will be a high-fat, low carbohydrate meal. At the other, it will be a high-carbohydrate, low-fat meal. Participants will have a tube inserted into a vein in their arm. They will have blood drawn via the tube 12 times in 8 hours: 2 times before they eat the breakfast and 10 times after. Participants will have other tests during their stays: * A resting metabolic test captures the air they exhale and measures how much energy they use at rest. * A dual energy X-ray absorptiometry (DXA) scan measures how much fat and muscle they have. * A Fibroscan is a special type of ultrasound of the liver. * A body surface scan uses lasers to measure the total area of the body. * A bioelectric impedance (BIS) exam measures how fast small electric currents move through their body. Participants may opt to have a third visit. At this visit, the breakfast will be high in protein....

Effects of Oculomotor Exercises in Patients With Non Traumatic Cervical Dizziness

To investigate the effects of oculomotor exercises on pain disability, dizziness and gaze stability in patients with non-traumatic cervical dizziness.

Acute Effects of Vibration Versus High-Intensity Resistance Conditioning on Neuromuscular Performance

The purpose of this randomized crossover study was to compare the immediate effects of high-intensity resistance conditioning and whole-body vibration conditioning on lower- and upper-body neuromuscular performance in recreationally resistance-trained young adults. Twenty participants were enrolled, and 19 completed both experimental conditions. After a preliminary assessment and familiarization session, participants completed the resistance-conditioning and vibration-conditioning protocols in a randomized order during two experimental sessions separated by 24 hours. The resistance-conditioning protocol included three squat repetitions at 90% of estimated one-repetition maximum before countermovement jump testing and three bench-press repetitions at 90% of estimated one-repetition maximum before an isometric push-up assessment. The vibration-conditioning protocol included lower- and upper-body vibration exercises performed on a vibration platform before the corresponding performance assessments. Lower-body performance was assessed using countermovement jump height, flight time-to-contraction time ratio, and relative peak power. Upper-body performance was assessed using peak force during an isometric push-up. All performance outcomes were measured using dual force desks.

Study Comparing AAA817+ARPI Versus Standard of Care in Adult Participants With PSMA-positive mCRPC

The purpose of this study is to determine whether \[225Ac\]Ac-PSMA-617 (AAA817), given for up to 6 cycles at a dose of 10 Megabecquerel (MBq) +/- 10%, plus androgen receptor pathway inhibitor (ARPI), improves the radiographic progression free survival (rPFS) compared to investigator's choice of standard of care (SOC) (ARPI change or taxane-based chemotherapy or \[177Lu\]Lu-PSMA-617 (AAA617)) in adult participants with PSMA-positive metastatic castration resistant prostate cancer (mCRPC) treated with another ARPI as last treatment and who have not been exposed to a taxane-containing chemotherapy in the mCRPC setting nor have received any prior PSMA-targeting radioligand therapy.

Adebrelimab Plus Temozolomide ± Hyperbaric Oxygen for Primary Glioblastoma

This is a prospective, randomized, open-label, multicenter phase II study. Newly-diagnosed primary glioblastoma patients who have undergone maximal safe resection or biopsy and completed standard concurrent chemoradiotherapy will be enrolled. Subjects will be randomized 1:1 into Arm A (Adebrelimab + Temozolomide + Hyperbaric Oxygen Therapy) or Arm B (Adebrelimab + Temozolomide). The primary endpoint is progression-free survival(PFS). Secondary endpoints include overall survival(OS), objective response rate(ORR), disease control rate(DCR), change of KPS score, safety including TRAE, irAE and SAE. Exploratory objectives include correlation analysis between baseline clinical characteristics / hyperbaric-oxygen-related biomarkers and efficacy-safety outcomes.

A Phase I Clinical Trial to Evaluate CMS-F021 Following Single and Multiple Doses in Healthy Participants

"This study is a first-in-human (FIH) trial of CMS-F021 conducted in healthy Chinese adult participants, consisting of two parts: Part 1-a single ascending dose (SAD) study (referred to as Part 1 SAD), and Part 2-a multiple ascending dose (MAD) study (referred to as Part 2 MAD). The study aims to evaluate the safety, tolerability, pharmacokinetic (PK) characteristics of CMS-F021 gel following single and multiple topical administrations in healthy Chinese adult participants. Both parts of the study are designed as randomized, double-blind, placebo controlled, sequential cohort trials. Part 1 SAD plans to include 5 dose cohorts,with 8 participants per cohort (6 receiving CMS-F021 and 2 receiving placebo),for a total of 40 participants. Part 2 MAD plans to include 4 dose cohorts, with 8 participants per cohort (6 receiving CMS-F021 and 2 receiving placebo), for a total of 32 participants."

Multivessel Minimally Invasive Coronary Bypass Grafting as HYBRID Revascularization Versus Conventional Off-pump Coronary Artery Bypass Grafting

The MICRA-HYBRID trial is a prospective, multicenter, randomized controlled study comparing multivessel hybrid coronary revascularization (HCR) as minimally invasive arterial bypass grafting to left-sided coronary targets (LAD and LCx) plus PCI of the RCA versus conventional off-pump coronary artery bypass grafting (OPCAB) via median sternotomy in patients with three-vessel coronary artery disease. The primary goal is to evaluate whether multivessel-HCR provides superior 30-day "textbook" clinical outcomes (mortality, MI, stroke, re-exploration for bleeding, and other complications) while improving perioperative recovery and long-term cardiovascular outcomes.

Immune Cell Response to Stimuli

This study will investigate the response of immune cells (neutrophils, monocytes) to various signals in the test tube to determine how they sense the signals in the body and what substances they produce in response to them. It will determine how the cells may, under certain circumstances, contribute to inflammation, and will measure substances in the blood plasma (the liquid, non-cellular part of the blood) that might stimulate white blood cells, in order to understand how the blood responds to possible disease-related conditions. Healthy normal volunteers 18 years of age and older who weigh at least 110 pounds may be eligible for this study. Participants give about 320 milliliters (mL) of blood (about 1 1/3 cups) or less at each donation. They donate no more than once every 8 weeks and no more than six times a year. On some occasions, less than 320 mL of blood may be drawn. The collected blood is separated into its components and specific cells are exposed to substances to examine their response.