Use of anti-hypertensive medications and post-transplant renal allograft function in children.

Post-transplant hypertension is a common occurrence in children. The relative effect of this hypertension on renal allograft function is uncertain. Examining the accumulated data for pediatric renal transplant recipients at our institution from monthly visits for up to three years, we determined whether the use of anti-hypertensive medications (anti-HTN medications) was associated with allograft dysfunction. Monthly clinical data included height, weight, serum creatinine, cyclosporin A (CsA) trough levels, number of acute rejection episodes, and number of anti-HTN medications. Estimated glomerular filtration rate (eGFR) was calculated monthly for each patient using the Schwartz formula. Time post-transplant was grouped into 6-month intervals. One thousand three hundred and sixty-three monthly data sets from 6 months (n = 76 patients) to 3 yr post-transplant (n = 47 patients) were analyzed. Overall mean eGFR was 75 mL/min/1.73 m2 at 6 months and 54 mL/min/1.73 m2 at 3 yr. A lower eGFR was found at all post-transplant time intervals for patients receiving anti-HTN medications compared with those who were not (p < 0.01). This lower eGFR was found at some but not all times post-transplant when patients were grouped by donor type or history of acute rejection episodes and analyzed separately. Mean CsA trough levels were higher at all post-transplant time intervals in patients receiving anti-HTN medications (p < 0.05). While a causal relationship between post-transplant hypertension and graft dysfunction cannot be established from this study, we conclude that the need for anti-HTN medications is associated with worse allograft function.

Serial estimation of glomerular filtration rate in children after renal transplant.

Evaluation of serial monthly estimated glomerular filtration rate (eGFR) may be useful for studying pediatric renal allograft outcome. To determine the validity of this approach, we reviewed our single-center experience in pediatric renal transplant recipients to determine the effect of risk factors for renal allograft failure on eGFR. Clinical parameters recorded monthly through 5 years post transplant allowed serial assessment of eGFR. Monthly clinical data included height, weight, serum creatinine, cumulative number of acute rejection episodes, cyclosporine dose, and cyclosporine trough levels. From these data, eGFR was calculated monthly for each patient using the Schwartz formula. Time post transplant was grouped in 6-month intervals and plotted against mean eGFR to compare eGFR in patients grouped by demographic and clinical factors; 1,786 monthly data sets from 6 months post transplant (n=76 patients) to 5 years post transplant (n=25 patients) were analyzed. Overall mean eGFR from 6 months to 1 year was 75 ml/min per 1.73 m(2) and from 4. 5 to 5 years 46 ml/min per 1.73 m(2). eGFR was lower at all time intervals for recipients of cadaver versus living-related donor grafts, and patients with >/=1 versus 0 acute rejections (P<0.01). After 1 year, eGFR was lower in black patients compared with white or Hispanic patients (P<0.01). Cyclosporine dose greater than 5 mg/kg per day was associated with better early and worse late graft function. These results are similar to those reported in multi-center studies using the outcome variable of graft failure and suggest that serial eGFR may be valid as an outcome variable to study chronic renal allograft dysfunction in children.

Oxygen Concentration in Isolated Chloroplasts during Photosynthesis.

The O(2) concentration in intact and osmotically disrupted isolated spinach (Spinacia oleracea, L.) chloroplasts during photosynthesis was estimated. The chloroplasts were allowed to reduce 3-phosphoglycerate, CO(2), or ferricyanide in light until the rate of O(2) production was linear. When the light was turned off O(2) evolution from the chloroplasts continued for a few seconds. This prolonged O(2) evolution is due to an O(2) surplus inside the chloroplasts which equilibrates with that in the medium. From this surplus the O(2) concentration inside the chloroplasts at the moment when the light had been switched off was calculated. In all experiments the O(2) concentration inside the photosynthesizing chloroplasts was higher than that outside, but was dependent upon the O(2) concentration of the chloroplast medium. At low external O(2) concentration (30 mum) the ratio of the internal to the external O(2) concentration was about 5, whereas at concentrations corresponding to those in airsaturated water this ratio was close to 1. With osmotically broken chloroplasts this ratio was 1.2 at 30 mum O(2) and almost 1 from 150 mum onward. When the O(2) surplus found in broken chloroplasts during photosynthesis was related to the volume of the thylakoids, a ratio of about 2.3 was observed.