Resistance of human regulatory Foxp3+ T cells to normobaric hyperoxia exposure under resting and stimulating conditions.

Oxygen tension levels may modulate immune responses. Evidence shows that hyperoxia influences the risk of infection, autoimmunity and alloreactivity and hence is a possible therapeutic option in a number of disorders. Regulatory T cells (Tregs) play a central role in tolerance maintenance, but their behaviour under hyperoxia is largely unknown. We investigated in vitro the impact of normobaric hyperoxia on human Tregs and their cellular network. Peripheral blood mononuclear cells isolated from six healthy men were cultured under normoxia and escalating duration of normobaric hyperoxia (10 min, 1, 16, 88 h) under resting conditions and at the presence of anti-CD3/CD28 beads. Foxp3+ Tregs' and other T cell subsets' survival, proliferation, activation, maturation and Th1/Th2 markers were assessed by flow cytometry. We observed decreasing CD4+ cell survival with increasing duration of hyperoxia irrespectively of the presence of stimulators. The prevalence of CD4+ CD45RA+ cells increased under stimulation (P=0.001). In stimulated samples, the proliferation and induced Foxp3 expression decreased after 88 h of hyperoxia (both P=0.001). In conclusion, normobaric hyperoxia up to 16 h does not induce significant changes in basic human T cell subsets, including the prevalence naturally occurring Tregs. Prolonged exposure to hyperoxia likely affects all unstimulated T cell subsets in a similar way. In stimulated T lymphocytes, the proliferation is hampered and cell death increases more evidently after prolonged hyperoxia (several days). Inducible Foxp3 expression is likely closely related to these processes. Naive CD4+ T cells are maintained by stimulation during exposure to hyperoxia.

Treatment of growth failure with growth hormone in children with chronic kidney disease: an open-label long-term study.

AIMS: To assess long-term efficacy and safety of recombinant human growth hormone (GH) in children with chronic kidney disease (CKD). METHODS: An open-label, international, multicenter study. Children with CKD and growth failure received GH (0.35 mg/kg/week). The primary efficacy endpoint was a significant change in height velocity (HV) and height standard deviation score (SDS) versus baseline after 12 months of treatment, extended to 24 months, then to 5 years. RESULTS: In total, 81 patients enrolled (CKD Stage 4 - 5 = 37, on dialysis = 27, post-transplant = 17). After 12 and 24 months of treatment, increases were seen in mean (SD) HV (4.6 (3.1) to 9.0 (3.6) cm/year and 4.5 (3.3) to 7.5 (2.9) cm/year, respectively; both p < 0.001), mean (SD) height SDS (-3.7 (1.7) to -3.0 (1.7) and -3.6 (1.5) to -2.5 (1.5), respectively; both p < 0.001) and mean (SD) HV SDS (-2.4 (2.5) to 3.8 (4.5) and -2.4 (2.2) to 1.1 (3.8), respectively; both p < 0.001). A normal height SDS was seen in 1% of children at baseline, 17% after 12 months and 43% after 24 months of treatment. Improvements were similar across CKD subgroups with the greatest improvements in CKD Stage 4 - 5. Among 31 patients who completed about 5 years of treatment, four reached final height. There was no undue bone age acceleration and no deterioration of kidney function. Ten adverse events were related to GH treatment. CONCLUSIONS: In this long-term study, GH treatment was associated with significant improvements in growth and height in children with CKD and growth failure, and was well tolerated.

Cytometry-acquired calcium-flux data analysis in activated lymphocytes.

Flow cytometry enables the sequential determination of calcium levels in millions of stimulated lymphocytes over a short period of time. Current algorithms available are not suitable for the statistical analysis of this large amount of data. The authors aimed to develop a robust algorithm that fits a function to median values of measured data and provides an opportunity for statistical comparison between different calcium-flux measurements. The alteration of calcium signal was monitored in CD4+ cells loaded with calcium binding fluorescent dyes and stimulated with phytohemagglutinin; the alteration of calcium signal was monitored for 10 minutes. The authors also reanalyzed published calcium-flux data of CD3+ cells and Jurkat cells stimulated with different concentrations of anti-CD3 and thapsigargin. The authors fitted different functions to the medians of data per time unit and identified hormesis function as the best fitting one. On the basis of the optimally fitting function, the authors calculated the most relevant biological descriptors such as starting value, peak, time to reach the maximum, and time to reach 50% of maximum before and after the peak. Statistically significant differences in cell activation kinetics at different stimulatory concentrations were also demonstrated. This approach enables us to characterize the kinetics and distribution of calcium-flux data derived by flow cytometry and may be a reliable tool for the characterization of lymphocyte activation (for details see: http://calciumflux.intralab.eu).

Post-transplant diabetes mellitus in children following renal transplantation.

PTDM plays a role in chronic allograft nephropathy and decreases graft and patient survival. Considering the serious outcome of chronic hyperglycemia, the importance of early recognition and the few data in children, in this retrospective analysis we studied the characteristics and risk factors of PTDM in 45 pediatric renal transplant recipients receiving Tac or CyA-based immunosuppression. Fasting blood sampling and OGTT were performed. PTDM has been developed in six patients (13%), while seven children (16%) had IGT, with the overall incidence of a glucose metabolic disorder of 29% in pediatric renal transplants. Patients in the PTDM + IGT group were younger and had higher systolic blood pressure and serum triglyceride level than children with normal glucose tolerance. Multivariate analysis identified Tac treatment, Tac trough level, steroid pulse therapy and family history of diabetes to be associated with the onset of PTDM. In pediatric renal transplants, OGTT and frequent assessment of blood glucose levels might be essential not only in the post-transplant management, but also prior to transplantation, particularly with family history of diabetes. Careful monitoring and modified protocols help to minimize the side effects of Tac and corticosteroids.

Do regulatory T cells contribute to Th1 skewness in obesity?

BACKGROUND: Recent data suggest that an increased prevalence of interferon-gamma (IFN-gamma) producing CD4 (+) cells is present in obesity. Regulatory T cells (Tregs) have a strong impact on activation and proliferation of CD4 (+) lymphocytes. Data are not available about Tregs and their possible contribution to chronic mild inflammation in obesity. DESIGN: We investigated the prevalence of Tregs in obese children. We also collected data about dendritic cells and monocytes (so-called antigen presenting cells, APCs), important modulators of Tregs and we determined the cytokine production of CD4 (+) lymphocytes, the main target cells of Tregs. METHODS: Twelve obese children and 10 healthy age-matched controls have been enrolled. For flow cytometric analyses, peripheral blood mononuclear cells were used. We determined the prevalence of Tregs by Foxp3 expression of CD4 (+) cells; prevalence of myeloid and plasmacytoid dendritic cells (DCs); prevalence of tumor necrosis factor (TNF)-alpha and interleukin(IL)-12 producing monocytes; and prevalence of IL-2, IL-4 and IFN-gamma producing CD4 (+) cells. RESULTS: The prevalence of Tregs, DCs, TNF-alpha and IL-12 producing macrophages, IL-2 and IFN-gamma producing CD4 (+) cells was similar in both groups. The prevalence of IL-4 producing CD4 (+) cells was lower in obese children than in healthy controls (p=0.028). The ratio of IFN-gamma (+)/ IL-4 (+) CD4 (+) cells was higher in obese children than in those with normal weight (p=0.046). CONCLUSIONS: CD4 (+) reactions are polarized toward Th1 direction in obesity. The unaltered number of Treg and APCs suggests that these immune regulator cells do not contribute to altered immune status in obese children.

Investigation of regulatory T cells in anorexia nervosa.

OBJECTIVE: The aim of our study was to determine, how severe calorie restriction in anorexia nervosa (AN) may influence regulatory T (Treg) cells and their cellular networks, that is, their main inducers (dendritic cells (DC) and monocytes) and their target cells, CD4+ lymphocytes. DESIGN: We measured the prevalence of Tregs, myeloid and plasmocytoid DC. The prevalence of tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-12-positive monocytes, IL-2, IL-4 and interferon (IFN)-gamma positive CD4+ cells was determined by intracellular staining after activation. SETTING AND SUBJECTS: In total, 21 AN patients and 19 healthy age-matched controls (body mass index values, median (range): 14.9 (11.1-17.4) vs 23.2 (19.5-27.4) kg/m(2)) have been recruited. RESULTS: Prevalence of Tregs, DCs, TNF-alpha and IL-12-positive monocytes, IL-4 and IFN-gamma-producing CD4+ cells were similar in AN and controls. The prevalence of IL-2-positive CD4+ cells was somewhat lower in AN (% value, median (range): 12.05 (7.50-16.70) vs 14.40 (12.00-22.00), P<0.05). None of these parameters correlated with the patients' clinical characteristics. CONCLUSIONS: Our results suggest that the antigen presenting cell - regulatory T cell - CD4+ lymphocyte axis is not affected by calorie and nutritional deficiency.

Association of interferon gamma T+874A and interleukin 12 p40 promoter CTCTAA/GC polymorphism with the need for respiratory support and perinatal complications in low birthweight neonates.

BACKGROUND: Data support the role of interferon (IFN)gamma and interleukin (IL)12 in perinatal complications. IFNgamma T(+874)A and IL12 p40 promoter CTCTAA/GC polymorphisms may have an effect on cytokine production. METHODS: DNA was extracted from dried blood samples of 153 low birthweight (LBW) infants and 172 healthy term infants. IFNgamma and IL12 genetic polymorphisms were determined to investigate the association between polymorphisms and ventilation characteristics, bronchopulmonary dysplasia (BPD) and other perinatal disorders. RESULTS: The IFNgamma(+874)A allele was over-represented in LBW infants. Carriers of the IFNgamma(+874)T allele required mechanical ventilation and oxygen supplementation for time periods 41% and 35%, respectively, shorter than those required by those not carrying the IFNgamma(+874)T allele. Stepwise logistic regression analysis showed that carriers of the IFNgamma(+874)T allele were protected against BPD (odds ratio (OR) 0.35 (95% confidence interval (CI) (0.12 to 0.99))) and patent ductus arteriosus (OR 0.43 (95% CI 0.19 to 0.97)), whereas carriers of the IFNgamma(+874)A allele were at higher risk of severe hypotension (OR 3.40 (95% CI 1.01 to 11.52)) and respiratory distress syndrome (OR 4.03 (95% CI 1.30 to 12.50)). Carriers of the IL12 GC allele were protected against pneumonia (OR 0.32 (95% CI 0.14 to 0.75)). Carriers of the IL12 CTCTAA allele were at higher risk of developing necrotising enterocolitis (NEC; OR 2.37 (95% CI 1.01 to 5.53)). CONCLUSIONS: Carrier state of the IFNgamma(+874)A allele presents an increased risk for premature birth and lung damage, as well as other perinatal complications. The risks of pneumonia and NEC are higher in heterozygotic carriers of the IL12 CTCTAA/GC polymorphism. Further studies are needed to determine whether these associations are the result of altered cytokine-producing capacity in infants carrying the tested alleles.

Altered mitochondrial response to activation of T-cells in neonate.

UNLABELLED: Mitochondrial functions have a major impact on T-cell functionality. In this study we characterized whether mitochondrial function in the neonatal T-cells differs from that in the adult T-cells during short T-cell activation. METHODS: We used flow cytometry methods to test mitochondrial mass and to monitor mitochondrial Ca²âº levels, mitochondrial potential and superoxide generation in parallel with cytoplasmic Ca²âº levels during phythohaemagglutinine-induced activation of CD4+ and CD8+ T-cells of 12 term neonates and 11 healthy adults. RESULTS: Baseline mitochondrial mass of CD4+ and CD8+ cells was lower in the neonate than in the adult. In comparison with the adult, neonatal resting CD4+ T-cells had lower cytoplasmic Ca²âº levels and this was associated with normal activation induced Ca²âº-response. During short-term activation cytoplasmic Ca²âº-response was lower in neonatal than in adult CD8+ T-cells. Mitochondrial Ca²âº uptake was increased in CD4+ neonatal T cells while it decreased in CD8+ T-cells. Mitochondrial depolarization was increased in CD4+ and decreased in CD8+ neonatal T-cells compared to adults. Superoxide generation was higher and equal in neonatal CD4+ and CD8+ cells, respectively, compared to the adult ones. CONCLUSION: Our data suggest that neonatal T-cells exhibit marked differences in mitochondrial function and superoxide generation compared to adult T-cells.

In vitro effect of human recombinant growth hormone on lymphocyte and granulocyte function of healthy and uremic children.

The recombinant human growth hormone (rhGH), currently used in supraphysiological doses to promote growth acceleration in chronic renal failure children (CRF), also has the ability to influence their impaired immune functions. The effect of human growth hormone on the lymphoproliferative response in vitro was analyzed in the peripheral blood lymphocytes of 25 healthy and 11 uremic children. In 72% of the uremic cases and in 60% of the healthy individual children the hormone increased the lymphoproliferation alone, and/or when used in combination with phytohaemagglutinine. The range of the effective hormone concentrations differed individually. Using semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) a great variation in the gene expression of growth hormone- (GH)-receptor in peripheral lymphocytes was detected. The respiratory burst activity of peripheral polymorphonuclear leukocytes (PMN) in vitro, in response to GH alone and when combined with suboptimal dose of phorbolester (PMA), was assessed by measuring luminol enhanced chemiluminescence in ten uremic and 18 healthy children. In six out of the ten of the CRF patients and in eight out of 18 of the healthy children the GH enhanced the oxidative burst activity of granulocytes provoked by a suboptimal dose of PMA. However, the effective doses (10, 50 and 300 ng/ml) and incubation times (0, 45 and 90 min) showed individual variations. Our data suggest that rhGH treatment in uremic children could be advantageous considering this population's enhanced susceptibility to bacterial, viral and fungal infections.

Hormonal regulation of water metabolism in children with nephrotic syndrome.

The roles of the antidiuretic hormone arginine-vasopressin (AVP), atrial natriuretic peptide (ANP), renin, aldosterone and catecholamines in the pathogenesis of impaired water excretion were studied in edematous children with nephrotic syndrome. Compared to non-proteinuric children with nephrotic syndrome in remission, edematous children during relapse had lower serum concentrations of sodium and chloride with lower plasma osmolality, but had higher hematocrit values (P less than 0.05, each). Plasma concentration of AVP was higher in edematous children (P less than 0.01). Compared to healthy, normal children, edematous nephrotic children had higher plasma concentrations of AVP, aldosterone, renin, noradrenaline, and adrenaline (P less than 0.01, each), but had similar levels of plasma ANP. Head out water immersion and infusion of 5 ml/kg 20% human serum albumin solution, both procedures known to increase central blood volume, resulted in a reduction of elevated hormone concentrations to near-normal levels and caused a rise in sodium and water excretion. Following albumin infusion, mean ANP rose fivefold, and plasma concentrations of this hormone correlated positively with urine flow (r = 0.64, N = 18, P less than 0.01) and with sodium excretion (r = 0.62, N = 18, P less than 0.01). It is concluded that AVP, renin, aldosterone and catecholamines are stimulated in edematous children with nephrotic syndrome by reduction in effective circulatory blood volume. Central blood volume expansion induced either by water immersion or by infusion of concentrated albumin solution is able to correct elevated hormone levels and to induce salt and water excretion. Plasma ANP appears to trigger the diuretic and natriuretic effects of central volume expansion.

Direct renovascular effect of somatostatin in the dog.

Recently, effects of somatostatin on the renal function have been described and the vasoactive properties of the peptide were proposed to contribute to this action. However, the available data on its effect in the renal vascular bed are very controversial. Therefore, we investigated the effect of local intaarterial somatostatin boluses in a wide range of doses (5 x 10(-11) - 5 x 10(-5) g) on the renal blood flow (RBF) in anesthetized dogs. RBF was measured by an electromagnetic flow probe. Somatostatin did not influence blood pressure or heart rate. RBF exhibited a significant, dose-dependent fall (ranging from 11.6 +/- 11.9% to 31.9 +/- 17.3%), with a threshold at a dose of 5 x 10(-10) g. These results offer conclusive evidence for the contribution of somatostatin-induced direct renal vasoconstriction to its renal effects, in addition to the demonstrated modulation of other vasoactive systems and tubular functions.

Red cell sodium-lithium countertransport and blood pressure in children with insulin-dependent diabetes mellitus.

Sodium-lithium countertransport and blood pressure responses, maximal elevated plasma norepinephrine concentrations induced by acute physical work load and the carbohydrate metabolic state were analyzed in 40 children suffering from insulin-dependent diabetes mellitus (IDDM). Patients were selected according to the duration of the disease to get a horizontal insight into the progression of the diabetes. Sixteen healthy children served as controls. Sodium-lithium countertransport (Na-Li CT) was 281 +/- 64 mumol/l red blood cells (RBC) per hour in the control group. Na-Li CT was elevated in all diabetic groups (newly diagnosed: 455 +/- 48; diabetics for 5-7 years: 495 +/- 48; diabetics for 10-13 years: 470 +/- 36). Plasma norepinephrine concentration increased during physical exercise, the elevation was more pronounced in diabetic children being 13.5 +/- 10.4, 10.1 +/- 5.0 and 12.3 +/- 5.4 nmol/l in the three diabetic groups, respectively, which differed significantly from that of controls (7.94 +/- 2.9; P < 0.01). Systolic blood pressure increased significantly during physical exercise in each group. However, maximal elevated systolic blood pressure was higher in children who had diabetes for more than 10 years than in controls (158 +/- 11 vs. 137 +/- 9.7 mmHg; P < 0.001). Na-Li CT correlated positively with the maximal systolic blood pressure measured during physical exercise in those diabetic children who suffered from diabetes for more than 5 years. High activity of Na-Li CT in combination with elevated blood pressure and high plasma concentration of norepinephrine induced by acute physical exercise may represent a risk of renal/vascular complications in patients suffering from IDDM.

Bone mineral content and density in asymptomatic children with coeliac disease on a gluten-free diet.

OBJECTIVES: Osteoporosis is a complication of coeliac disease. A gluten-free diet improves but does not normalize bone mineral density in adult patients. Only limited data are available regarding the influence of the disease and diet on bone mineralization in children. The aim of this study was to evaluate the radial bone mineral content and density in children and adolescents who are asymptomatic on a gluten-free diet. SUBJECTS AND METHODS: The bone mineral content (BMC) and density (BMD) values of the non-dominant radius midshaft in 91 children (53 girls, 38 boys, mean age 11.7 years, mean duration of disease 8.7 years) were determined by single-photon absorptiometry. At the diagnosis and at least three years after commencement of a gluten-free diet, serum calcium, phosphorus, albumin concentrations and alkaline phosphatase activities were measured in all patients, and intact parathormone concentrations in 16 patients. RESULTS: The mean BMC Z-score value in the female adolescent group only was significantly lower than normal (mean Z-score -1.04, P < 0.01). In contrast, the mean BMD Z-score was significantly higher compared to a healthy population both in girls (mean Z-score +1.36, P < 0.001) and in boys (mean Z-score +0.53, P < 0.02), as well as in the total patient group (mean Z-score +1.01, P < 0.001). The radial diameter was significantly smaller than normal in both pre-pubertal and adolescent groups. Serum laboratory parameters of asymptomatic patients were in the normal range. The parathormone mean value was significantly lower after at least three years of gluten-free diet than at diagnosis (mean +/- SD 3.77 +/- 1.07 versus 7.89 +/- 2.54 pmol/l, P < 0.01), but significantly higher compared to controls (2.89 +/- 0.90 pmol/l, P < 0.05). CONCLUSIONS: These data indicate that treated, asymptomatic coeliac children and adolescents have normal or even higher radius mineral density values than controls, but the bone size remains reduced. Although there is no direct evidence of calcium malabsorption in this cohort of coeliac patients, the slightly higher parathormone levels, together with some other factors, particularly delayed puberty, may result in reduced bone size.

Developmental changes in erythrocyte Na(+),K(+)-ATPase subunit abundance and enzyme activity in neonates.

AIM: To study the relation between erythrocyte Na(+),K(+)-ATPase subunit isoform composition, Na(+),K(+)-ATPase activity, and cation pump function in preterm and term neonates. DESIGN: Erythrocyte Na(+),K(+)-ATPase subunit isoform abundance, Na(+),K(+)-ATPase activity, and cation pump function were studied in blood samples obtained from 56 preterm neonates of 28-32 weeks gestation (group 1), 58 preterm neonates of 33-36 weeks gestation (group 2), and 122 term neonates (group 3) during the first two postnatal days. RESULTS: alpha(1) isoform abundance was higher and beta(2) isoform abundance was lower in group 1 than in group 3 (p = 0.0002). alpha(2) and beta(1) isoform abundance did not change with maturation and there was no evidence for the presence of the alpha(3) isoform. Gestational age was inversely related to Na(+), K(+)-ATPase activity (p = 0.0001) and directly related to intracellular Na(+) concentration (p = 0.0025). CONCLUSIONS: Expression of the alpha(1) and beta(2) Na(+),K(+)-ATPase subunit isoforms is developmentally regulated. The increased abundance of alpha(1) isoforms of immature neonates translates to increased ATPase activity. The lower intracellular Na(+) concentration of immature neonates suggests that their erythrocyte Na(+),K(+)-ATPase cation pump function may also be increased.

Effect of low-dose dopamine on kidney function and vasoactive hormones in pediatric patients with advanced renal failure.

Dopamine (DA) was infused in a dose of 2 micrograms/kg/min in 12 children and adolescents with chronic renal failure to test the vasodilatory reserve capacity of the kidney. Mean basal GFR and ERPF were 17.8 and 93.1 ml/min/1.73 m2, respectively. DA infusion had no significant influence on GFR but effective renal plasma flow (ERPF) increased by 14% (p less than 0.05). After DA, GFR did not correlate with ERPF. There was a significant increase in urinary sodium excretion (+22%). Sodium excretion correlated with osmotic clearance and urine flow rate with free water clearance. Plasma prolactin concentration was decreased (p less than 0.01), whereas noradrenaline, adrenaline and free dopamine increased significantly after DA. Plasma renin activity, aldosterone, arginine vasopressin and atrial natriuretic peptide levels remained unchanged. The data indicate that in pediatric patients with advanced renal failure DA fails to increase filtration capacity, whereas effective renal plasma flow and sodium excretion are stimulated. It is speculated that in this situation preglomerular and tubular renal functions regulated by dopamine receptors are better conserved than those affecting glomerular microcirculation.

Effect of propranolol on heart rate variability in patients with end-stage renal disease: a double-blind, placebo-controlled, randomized crossover pilot trial.

BACKGROUND: Low heart rate variability (HRV) is an independent risk factor of cardiac mortality in patients with end-stage renal disease (ESRD). It has been explained by uremic parasympathetic neuropathy. Sympathetic overactivity can also reduce HRV. Our aim was to determine whether there is vagal activity in ESRD patients that is masked by sympathetic activity. METHODS: The effect of propranolol on HRV was examined in 13 patients with ESRD, aged 20.1 +/- 7.6 years without diabetes. All patients were given intravenous propranolol (0.05 mg/kg) once and placebo once in a randomized, double-blind way, with an interval of 6.6 days (mean, range: 2-9). Propranolol was administered before hemodialysis treatment, after 40 minutes supine resting period. HRV was registered for 10 minutes, during supine, before and after the injection. Patients' HRV data were compared to that of 29 age-matched healthy controls. RESULTS: Initially, both high-(HFV) and low-frequency (LFV) bands of heart rate variability were lower in ESRD patients compared to controls (p < 0.001 for both). Propranolol resulted in a significant increase of HFV (propranolol: AlgHFV = 0.182 (0.027 - 0.337), placebo: deltalgHFV = -0.029 (-0.128 - +0.070); p = 0.032). Elevation of LFV was not significant. Six patients had an elevated plasma norepinephrine and/or epinephrine level. Plasma dopamine level was elevated in all but 1 patient (mean: 432 pmol/l, 95% CI: 320-543) and showed an inverse relationship with the increase of IgHFV secondary to propranolol (r = -0.66, p = 0.014). CONCLUSIONS: Low HFV of ESRD patients can be improved by beta-adrenergic blockade. It demonstrates that there is some vagal activity in ESRD that is masked by sympathetic activity. Therefore, altered sympathovagal balance of ESRD patients should be taken into consideration in the assessment of vagal uremic neuropathy.

HbA1c levels and erythrocyte transport functions in complication-free type 1 diabetic children and adolescents.

Higher erythrocyte sodium-lithium countertransport activity (SLC) is implicated in the development of diabetic nephropathy. Altered glucose homeostasis and genetic susceptibility are claimed to play a role in the elevation of SLC. We aimed to test whether metabolic control or the genetic variants of G protein beta 3 (Gb3) subunits determine SLC and other erythrocyte transport activities in complication-free stage of type 1 diabetes. A total of 96 complication-free type 1 diabetic children and adolescents were enrolled. SLC, Na(+)/K(+)-ATPase (NAK) and Ca(2+)-ATPase (CA) were measured by functional assays in erythrocytes. Gb3-C825T polymorphism was determined by PCR-RFLP. Results were related to HbA(1c) and were compared to those of 97 healthy controls. SLC activity was higher in diabetics (387+/-146 vs. 280+/-65 mmol/RBC. hour) and correlated with HbA(1c) levels (y=0.004x+6.42, r=0.33, n=96, p<0.01). NAK and CA activities were unaltered. The prevalence of (825)T allele was similar in the patient and control groups (0.34 vs 0.37) and no differences in enzyme activities were observed between the (825)T allele-positive and negative subjects. Although metabolic control correlated with SLC, other membrane functions were not affected. Therefore we hypothesize that the relationship between advanced glycation and SLC elevation is not causative. Rather, a genetic susceptibility for the coexistence of poor metabolic control and higher SLC is more likely. However, the presence of Gb3-C825T variant is not likely to be a risk factor for SLC-elevation and altered metabolic control diabetes.

Reproducibility of erythrocyte sodium-lithium countertransport activity and ambulatory blood pressure measurements in type 1 diabetes mellitus.

We aimed to study the reproducibility of sodium-lithium countertransport [SLCT] activity and ambulatory blood pressure monitoring [ABPM] in type 1 diabetes. We did this by performing repeated measurements of SLCT activity and ABPM in 11 recent-onset diabetic children and in 11 patients with longer duration of diabetes. Both parameters were related to microalbuminuria. In the older group of diabetic children a significant correlation [r = 0.78; P<0.005] in SLCT activity between the first and second study was observed [514.3+/-186.4 vs 491.0+/-148.0 micromol/l erythrocytes/h]. Diurnal systolic and diastolic blood pressure were comparable at both time points within the same group of diabetic children [in group 1: 102.6+/-6.1 vs 108.6+/-7.6 mmHg N.S.; in group 2: 113.4+/-10.6 vs 114.0+/-7.8 mmHg N.S. Diastolic blood pressure in group 1: 57.4+/-4.8 vs 65.7+/-6.9 mmHg N.S., in group 2: 70.6+/-9.1 vs 68.5+/-5.3 mmHg N.S.]. Moreover, there was a significant correlation in both diurnal and nocturnal systolic blood pressure between the first and second study in the whole diabetic population. Both SLCT activity and blood pressure values obtained by ABPM were found to be reproducible individual characteristic markers in type 1 diabetic children.

Regional differences in nitric oxide-dependent vascular responses to somatostatin.

The mechanisms of the vascular effects of somatostatin (ST) are not well known. This study compares the direct effect of ST in different vascular regions and species. Isolated perfused segments of the cat superior mesenteric artery in vitro did not exhibit a vascular response in the resting state, however, ST-induced vasodilatation was observed with norepinephrine preconstriction. In contrast, ST only slightly dilated superior mesenteric vein segments. In the artery, NG-nitro-L-arginine inhibited both ST and endothelium-dependent nitric oxide (NO) mediated response. No regular dose-response curves were found when ST was applied on the large mesenteric artery in the cat, but rings of small mesenteric artery from both cats and dogs exhibited dose-dependent relaxations. These effects were also NO-dependent. Local application of ST on the rat saphenous artery in situ elicited NO-mediated dose-dependent vasodilatation. However, ST constricted rat saphenous veins in the case of either adventitial or intraluminal application. It is concluded that ST exerts different actions on the arterial and the venous vessel wall. The major response in arteries is endothelium-mediated vasodilatation seen in various species and vascular beds. Large and small arteries respond differently to ST but these differences require further elucidation.