Effects of theophylline on erythropoietin production in normal subjects in patients with erythrocytosis after renal transplantation

Article Abstract:

After kidney transplantation, many patients develop erythrocytosis, an elevation in the number of red blood cells. The cause is not known, but the production of erythropoietin (a hormone that stimulates red blood cell production) is thought to increase after transplantation. Research evidence suggests that erythropoietin production may be enhanced by adenosine (a nucleotide). Prevention of this action of adenosine could be useful in treating erythrocytosis. To test this, eight kidney transplant recipients with erythrocytosis underwent treatment with theophylline (an adenosine antagonist, which blocks the action of adenosine) for two eight-week periods within a 28-week study period. A variety of blood tests were performed weekly. Five normal subjects underwent the same drug regimen, with blood tests performed less often. Theophylline produced a decline in the hematocrit (the percentage of blood volume due to red blood cells) and in erythropoietin levels in both the transplant patients and the control subjects. The red cell mass was also reduced in the patients. Prior to receiving theophylline, patients underwent weekly phlebotomy, the surgical opening of a vein to withdraw blood, (to reduce the high hematocrit). During treatment, the necessity of phlebotomy was virtually eliminated. Side effects of theophylline included headache, nervousness, and insomnia, but they were treatable, and not sufficiently severe to cause anyone to withdraw from the study. A discussion of the physiological actions of erythropoietin is provided. It appears that the use of theophylline could constitute an alternative to phlebotomy for kidney transplant patients to control erythrocytosis. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Measurement, Drug therapy, Kidneys, Kidney transplantation, Erythropoietin, Theophylline, Polycythemia

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Altered platelet calcium metabolism as an early predictor of increased peripheral vascular resistance and preeclampsia in urban black woman

Article Abstract:

Preeclampsia is a complication of pregnancy marked by high blood pressure, swelling, and protein in the urine, although other symptoms may be observed. The condition occurs in 5 to 6 percent of first pregnancies, and as many as 20 percent of inner-city woman are affected. Various cardiovascular irregularities which accompany preeclampsia are discussed. In this study, 48 young black women who had not previously given birth were studied experimentally. The women all had normal blood pressure, no previous history of high blood pressure, and were not taking medications or illicit drugs. The subjects' vascular system (hemodynamics) was studied during each trimester of pregnancy. Fourteen of the woman (29 percent) developed preeclampsia; the data obtained from these women and those who did not develop the condition were compared and analyzed. Specific measurements of platelets, small cell fragments involved in the blood clotting process, showed no significant difference between the two groups. However, when platelet preparations were treated with the drug arginine vasopressin, changes in platelet intracellular calcium levels were found that indicated impending preeclampsia. These changes may provide an early chemical marker for the development of preeclampsia. This may be an extremely valuable predictor because platelets are easily collected and the test has proven to be very sensitive. (Consumer Summary produced by Reliance Medical Information, Inc.)

Diagnosis, Testing, Causes of, Physiological aspects, Preeclampsia, Blood platelets, Calcium, Calcium (Chemical element)

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Antihypertensive therapy and the risk of type 2 diabetes mellitus

Article Abstract:

Giving patients with hypertension a beta blocker and an ACE inhibitor could lower their risk of developing type 2, or adult onset, diabetes. A study published in 2000 found that hypertensive patients who took beta blockers had a 28% increased risk of type 2 diabetes. ACE inhibitors, thiazide diuretics, and calcium channel blockers did not increase the risk of diabetes. In fact, other studies have shown that ACE inhibitors can lower the risk of diabetes in hypertensive patients. Despite the adverse effect of beta blockers, they are still valuable drugs for treating heart disease.

Editorial, Risk factors, Type 2 diabetes, Adrenergic beta blockers, Adrenergic beta-antagonists, Antihypertensive drugs, Antihypertensive agents

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