Patient case (clinical description): A 47-year-old woman comes to the office complaining of pain in the calf and knee when she bends down. The pain limits her activity. Her medical history is significant for osteoarthritis, for which she uses nonsteroidal anti-inflammatory drugs (NSAIDs) for the past two years. She is living with her husband and has 3 children. She doesn't smoke but drinks alcohol occasionally. Her vital signs are normal. On physical examination, there is a small effusion in the right knee. The effusion grew a little larger and she developed a tender swelling in the popliteal fossa and calf. Both the pain and swelling worsened as she bent and straightened her knee.

Patient's own account: I'm a 47-year-old woman, married with 3 kids. I don't smoke and I drink occasionally. I went to the doctor because of pain in my calf and knee when I was bending down. This has been limiting my daily activities. I have been diagnosed with osteoarthritis for which I have taken anti-inflammatory drugs for the past 2 years. The doctor saw a small fluid buildup in my right knee. This buildup became a bit bigger and I have a swollen calf. The pain is worse when I bend and straighten my knee.

Clinical trial: Effect of Nitrite on Exercise Physiology and Metabolism

Eligibility criteria:
-  INCLUSION CRITERIA:

        Subjects must be 21-45 years of age.

        Subject must be in good health and able to perform cycle ergometry for the length of the
        study.

        Subjects must provide informed, written consent for participation in this study.

        Female subjects of childbearing age must have a negative pregnancy test.

        EXCLUSION CRITERIA:

        Subjects with a history of cardiac, pulmonary, peripheral vascular, or mitochondrial
        disease.

        Subjects with abnormal EKG other than sinus bradycardia.

        Individuals with a future cardiovascular risk greater than 1 % in the next 10 years will be
        excluded from the study. Risk will be calculated using the Framingham risk calculator
        published on the web site: http://hin.nhlbi.nih.gov/atpiii/calculator.asp?usertype=prof.

        Subjects with any physical condition (for example, knee problems) that may impair their
        performance during exercise testing.

        Subjects who have a history of smoking within one year.

        Subjects with anemia (defined as hemoglobin less than 10 g/dL).

        Subjects with a history of reaction to a medication or other substance characterized by
        dyspnea and cyanosis will not participate in this study.

        Subjects with G6PD deficiency.

        Subjects with a baseline methemoglobin level greater than 1%.

        Lactating females who are breastfeeding, will not participate since nitrite crosses into
        breast milk and could cause methemoglobinemia in the infant.

        No volunteer subject will be allowed to take any medication (oral contraceptive agents are
        allowed), vitamin supplements, herbal preparations, nutriceuticals or other alternative
        therapies for at least one month prior to study and will not be allowed to take aspirin or
        NSAIDs for one week prior to study.

        Subjects with a blood pressure of less than 100/70 mmHg on the study day will be excluded
        from the protocol.
No condition on gender to be admitted to the trial.
No healthy subjects accepted to join the trial.
Subject must be at least 21 Years old.
Subject must be at most 45 Years

Eligibility (NLI label): Contradiction