Elevated CO2 alters anatomy, physiology, growth, and reproduction of red mangrove (Rhizophora mangle L.).

Mangroves, woody halophytes restricted to protected tropical coasts, form some of the most productive ecosystems in the world, but their capacity to act as a carbon source or sink under climate change is unknown. Their ability to adjust growth or to function as potential carbon sinks under conditions of rising atmospheric CO2 during global change may affect global carbon cycling, but as yet has not been investigated experimentally. Halophyte responses to CO2 doubling may be constrained by the need to use carbon conservatively under water-limited conditions, but data are lacking to issue general predictions. We describe the growth, architecture, biomass allocation, anatomy, and photosynthetic physiology of the predominant neotropical mangrove tree, Rhizophora mangle L., grown solitarily in ambient (350 µll-1) and double-ambient (700 µll-1) CO2 concentrations for over 1 year. Mangrove seedlings exhibited significantly increased biomass, total stem length, branching activity, and total leaf area in elevated CO2. Enhanced total plant biomass under high CO2 was associated with higher root:shoot ratios, relative growth rates, and net assimilation rates, but few allometric shifts were attributable to CO2 treatment independent of plant size. Maximal photosynthetic rates were enhanced among high-CO2 plants while stomatal conductances were lower, but the magnitude of the treatment difference declined over time, and high-CO2 seedlings showed a lower Pmax at 700 µll-1 CO2 than low-CO2 plants transferred to 700 µll-1 CO2: possible evidence of downregulation. The relative thicknesses of leaf cell layers were not affected by treatment. Stomatal density decreased as epidermal cells enlarged in elevated CO2. Foliar chlorophyll, nitrogen, and sodium concentrations were lower in high CO2. Mangroves grown in high CO2 were reproductive after only 1 year of growth (fully 2 years before they typically reproduce in the field), produced aerial roots, and showed extensive lignification of the main stem; hence, elevated CO2 appeared to accelerate maturation as well as growth. Data from this long-term study suggest that certain mangrove growth characters will change flexibly as atmospheric CO2 increases, and accord with responses previously shown in Rhizophora apiculata. Such results must be integrated with data from sea-level rise studies to yield predictions of mangrove performance under changing climate.

Can dialysis adequacy be achieved by tailoring the dialysis prescription in an Asian pediatric population on nightly intermittent peritoneal dialysis?

This study was undertaken to determine whether tailoring the dialysis prescription in Asian children on nightly intermittent peritoneal dialysis (NIPD), without adding high-dose therapy for cost-savings purposes, was able to achieve dialysis adequacy and improvement in nutrition. Eight children (age range: 5.5-20 years) on NIPD for a mean of 2.1 +/- 0.6 years, were studied at baseline and at 3 months and 9 months after their dialysis dose was tailored. Dialysis adequacy was measured by weekly Kt/Vurea and creatinine clearance (CCr). Fat-free mass (FFM) and percent body fat (%FAT) as measured by bioelectrical impedance, together with anthropometric measurements, serum total protein, and albumin, were used as indicators of nutrition. After the dialysis prescription was tailored, the mean weekly Kt/Vurea increased from 1.89 +/- 0.35 to 2.12 +/- 0.54 at 9 months, and total CCr increased from 36.4 +/- 11.51 L/1.73 m2 to 48.30 +/- 14.30 L/1.73 m2. The increase occurred despite a decline in residual renal function and was attributable to significant improvements in the peritoneal clearances of urea and creatinine (p < 0.05). The mid arm muscle circumference (MAMC) increased significantly (p = 0.006), while FFM increased from 25.68 +/- 7.92 kg to 26.95 +/- 9.83 kg, and %FAT decreased from 21.56% +/- 8.41% to 18.66% +/- 8.16%. The increase in FFM correlated significantly with a decrease in serum creatinine (r = -0.94, p = 0.005). In conclusion, tailoring the dialysis prescription in NIPD, without adding high-dose therapy, resulted in a trend of improvement in dialysis adequacy and some nutritional parameters.

Minimal change nephrotic syndrome--a complex genetic disorder.

INTRODUCTION: Minimal change nephrotic syndrome (MCNS) is the most common primary nephrotic syndrome in childhood. While the pathogenesis of this disease is still unknown, there is considerable evidence that it is an immune disease. This role of genetic susceptibility in this disease is the subject of this review. METHODS: Reported studies addressing potential genetic factors in MCNS were reviewed. These factors included human leukocyte antigen (HLA) associations, genes involved in the renin-angiotensin system and cytokines. RESULTS: Several authors have reported the presence of familial clustering, human leukocyte antigen (HLA) associations, and association with asthma and atopy, suggesting a genetic susceptibility to the disease. Moreover, recent studies on the role of the renin angiotensin system, cytokines and their respective receptors on the severity and clinical course of the disease, have lent further support to the immunogenetic basis of this disease. CONCLUSION: Knowledge of the genetic basis of MCNS may have important therapeutic implications in this disease, in particular, the role of cytokines and their respective receptors, including the influence of environmental factors on their expression.

Risk factors for steroid dependency in children with idiopathic nephrotic syndrome.

Minimal change disease, the most common cause of idiopathic nephrotic syndrome (INS) in children, has a high relapse rate, with approximately half of patients developing steroid dependency. This study was aimed at determining the predictive risk factors for the development of steroid dependency in children diagnosed with INS. A retrospective study of 123 children with steroid-responsive INS, followed for at least 6 months between December 1974 and December 1999, was conducted. The following parameters were studied as predictors of steroid dependency: age at onset, gender, race, microscopic hematuria at onset, atopy, concomitant upper respiratory tract infections (URTI) during relapses, and days to remission with initial steroid therapy. Of the 91 children who fulfilled the inclusion criteria, 61.5% became steroid dependent. Both univariate and logistic regression analyses revealed that initial remission time of 9 or more days (P=0.02, OR=3.0, 95% CI=1.2-7.9) and concomitant URTI during relapses (P=0.01, OR=3.4, 95% CI=1.3-8.8) were significant predictors of steroid dependency. By identifying those children with predictive factors of steroid dependency, the clinician will be better able to plan the long-term management of these patients and reduce the morbidity seen with the frequent relapses and steroid treatment, in a disease that is otherwise associated with a favorable prognosis.

Eighteen years experience in pediatric acute dialysis: analysis of predictors of outcome.

This study reviewed the 18-year experience of acute dialysis in the pediatric intensive care unit, in order to identify factors that could predict outcome, and to determine whether newer modalities of acute dialysis have influenced this outcome. Sixty-six children (ages 1 day to 19 years) received acute dialysis from May 1980 to April 1998. Factors predicting outcome were analyzed using univariate and Cox regression analysis. Modality of dialysis in the first 15 years was exclusively peritoneal dialysis. with a mortality of 63.9%. However, in the last 3 years, with increasing patient numbers, continuous hemodiafiltration (CHDF) was the modality of choice (56.7%), with a mortality of 73.3%. Univariate analysis showed that age <1 year, coma, acute tubular necrosis, disseminated intravascular coagulopathy, assisted ventilation, and hypotension were associated significantly with poor outcome (P<0.05). Cox regression analysis revealed that mortality was significantly higher in patients on mechanical ventilation (RR 5.96, 95% CI 1.82-19.50), or with age <1 year (RR 2.00, 95% CI 1.08-3.73). In conclusion, despite the increasing use of CHDF over the last 3 years, there was no significant improvement in mortality, probably related to the fact that more critically ill patients were dialyzed.