Management of bone disease in cystinosis: Statement from an international conference.

Cystinosis is an autosomal recessive storage disease due to impaired transport of cystine out of lysosomes. Since the accumulation of intracellular cystine affects all organs and tissues, the management of cystinosis requires a specialized multidisciplinary team consisting of pediatricians, nephrologists, nutritionists, ophthalmologists, endocrinologists, neurologists' geneticists, and orthopedic surgeons. Treatment with cysteamine can delay or prevent most clinical manifestations of cystinosis, except the renal Fanconi syndrome. Virtually all individuals with classical, nephropathic cystinosis suffer from cystinosis metabolic bone disease (CMBD), related to the renal Fanconi syndrome in infancy and progressive chronic kidney disease (CKD) later in life. Manifestations of CMBD include hypophosphatemic rickets in infancy, and renal osteodystrophy associated with CKD resulting in bone deformities, osteomalacia, osteoporosis, fractures, and short stature. Assessment of CMBD involves monitoring growth, leg deformities, blood levels of phosphate, electrolytes, bicarbonate, calcium, and alkaline phosphatase, periodically obtaining bone radiographs, determining levels of critical hormones and vitamins, such as thyroid hormone, parathyroid hormone, 25(OH) vitamin D, and testosterone in males, and surveillance for nonrenal complications of cystinosis such as myopathy. Treatment includes replacement of urinary losses, cystine depletion with oral cysteamine, vitamin D, hormone replacement, physical therapy, and corrective orthopedic surgery. The recommendations in this article came from an expert meeting on CMBD that took place in Salzburg, Austria, in December 2016.

Ascitic fluid drainage using a peritoneal dialysis catheter to prevent and treat multi-organ dysfunction in veno-occlusive disease in children undergoing hematopoietic stem cell transplantation.

Veno-occlusive disease (VOD), or sinusoidal obstruction syndrome, is a well-recognised, serious complication associated with the chemotherapy conditioning therapy used in hematopoietic stem cell transplantation (HSCT). Fluid management is typically challenging in children with this condition. We describe effective early use of peritoneal dialysis catheters to drain extravascular, intra-abdominal fluid in children with VOD, allowing intravascular fluid administration to preserve renal perfusion and function, preventing multi-organ dysfunction. All but one of the children are long-term survivors, both of their significant VOD and their HSCT. The child that did not survive died from their underlying metabolic illness, not VOD.

UK Renal Registry 18th Annual Report: Chapter 4 Demography of Patients Receiving Renal Replacement Therapy in Paediatric Centres in the UK in 2014.

A total of 917 children and young people under 18 years with established renal failure (ERF) were receiving treatment at paediatric nephrology centres in 2014.At the census date (31st December 2014), 79.3% of prevalent paediatric patients aged ,18 years had a functioning kidney transplant, 11.2% were receiving haemodialysis (HD) and 9.5% were receiving peritoneal dialysis (PD). In patients aged ,16 years, prevalence of ERF was 60.4 per million age related population (pmarp) and the incidence 9.4 pmarp. The most common primary renal diagnosis was renal dysplasia+reflux, present in 32.6% of prevalent paediatric patients aged ,16 years. About a third of patients had one or more reported comorbidity at onset of renal replacement therapy (RRT). The improvement in rates of pre-emptive transplantation for those referred early has been maintained over the last 10 years at 37.5%, compared to 27.4% in 2000­2004. At transfer to adult services, 90.3% of patients had a functioning kidney transplant. Survival during childhood amongst children commencing RRT was the lowest in those aged less than two years compared to those aged 12 to less than 16 years with a hazard ratio of 4.1 (confidence interval 2.2­8.0), and in those receiving dialysis compared to having a functioning transplant with a hazard ratio of 6.3 (confidence interval 3.9­10.2).

The complexity and difficulty of diagnosing lung cancer: findings from a national primary-care study in Wales.

AIM: This paper aims to provide a detailed analysis of the diagnostic process of lung cancer from a primary-care perspective. BACKGROUND: Diagnosing lung cancer at a stage where curative treatment is possible remains a challenge. Beginning to understand the complexity and difficulty in the diagnostic journey should enable the development of interventions in order to facilitate timelier diagnosis. METHODS: A national study of significant events was conducted whereby general practitioners (GPs) in Wales were asked to report data relating to the diagnostic process of recent lung cancer diagnoses using a standard template. Both qualitative and quantitative data were analysed. Findings Case reports were received from 96 general practices on 118 patients. A total of 96 patients (81.4%) presented with respiratory symptoms. A total of 79 patients (66.9%) had a GP-initiated X-ray before diagnosis. A total of 23 patients (19.5%) had a chest X-ray that did not initially show suspicion of lung cancer. A total of 25 patients (21.2%) were diagnosed after a GP-initiated acute admission. Analysis of free-text qualitative data showed that, for many patients, their GP behaved in an exemplary manner. However, for some patients, the GP could have made more of the opportunities presented for timelier diagnosis. There were a number of atypical and complex presentations, where the opportunities for more timely diagnosis were more limited. A variety of causes of diagnostic delays in secondary care were reported. These findings will inform health policy, and will inform the design of interventions to try to facilitate more timely diagnosis for symptomatic patients. We encourage greater compliance with diagnostic guidelines and greater vigilance for patients presenting with atypical symptoms, as well as for patients whose initial chest X-rays are normal.

LRIG2 mutations cause urofacial syndrome.

Urofacial syndrome (UFS) (or Ochoa syndrome) is an autosomal-recessive disease characterized by congenital urinary bladder dysfunction, associated with a significant risk of kidney failure, and an abnormal facial expression upon smiling, laughing, and crying. We report that a subset of UFS-affected individuals have biallelic mutations in LRIG2, encoding leucine-rich repeats and immunoglobulin-like domains 2, a protein implicated in neural cell signaling and tumorigenesis. Importantly, we have demonstrated that rare variants in LRIG2 might be relevant to nonsyndromic bladder disease. We have previously shown that UFS is also caused by mutations in HPSE2, encoding heparanase-2. LRIG2 and heparanase-2 were immunodetected in nerve fascicles growing between muscle bundles within the human fetal bladder, directly implicating both molecules in neural development in the lower urinary tract.

UK Renal Registry 16th annual report: chapter 13 clinical, haematological and biochemical parameters in patients receiving renal replacement therapy in paediatric centres in the uk in 2012: national and centre-specific analyses.

INTRODUCTION: The British Association for Paediatric Nephrology Registry (BAPN) was established to analyse data related to renal replacement therapy (RRT) in children. The registry receives data from the 13 paediatric nephrology centres in the UK. This chapter aims to provide centre specific data so that individual centres can reflect on the contribution that their data makes to the national picture and to determine the extent to which their patient parameters meet nationally agreed audit standards for the management of children with established renal failure (ERF). METHODS: Data returns included a mixture of electronic (92%) and paper (8%) returns. Data were analysed to calculate summary statistics and where applicable the percentage achieving an audit standard. The standards used were those set out by the Renal Association and the National Institute for Health and Clinical Excellence. RESULTS: Anthropometric data confirmed that children receiving RRT were short compared to healthy peers. Amongst patients with a height of <2SD between 2001 and 2012, 29.2%were receiving growth hormone if they were on dialysis compared to 11.9% if they had a functioning transplant. Prevalence rates of overweight and obese status in children with ERF remain concerningly high. Blood pressure control remained challenging with wide inter-centre variation although this was significantly better in children with a functioning transplant. Over a quarter of haemodialysis patients and 17.3% of peritoneal dialysis patients were anaemic, compared to only 8.3% of transplanted patients. ESA use in the dialysis population exceeded 90% amongst anaemic patients. The control of renal bone disease remained challenging. CONCLUSIONS: Optimising growth and reducing prevalent excess weight in children on RRT remains challenging. The likelihood of complete electronic reporting in the near future with plans for quarterly reporting in the format of the recently finalised NEW paediatric dataset will hopefully improve quality of data and their reporting, allowing improvements in patient care.

UK Renal Registry 13th Annual Report (December 2010): Chapter 5: demography of the UK paediatric renal replacement therapy population in 2009.

AIMS: To describe the demographics of the paediatric RRT population under the age of 16 years in the UK and to analyse changes in demography with time. METHODS: Extraction and analysis of data from the UK Renal Registry (UKRR). RESULTS: There were 751 children <16 years old with established renal failure (ERF) in the UK in December 2009. The reported prevalence under the age of 16 years was 65 per million age related population (pmarp) and the reported incidence 9.3 pmarp. The incidence and prevalence for South Asian patients was much higher than that of the White and Black populations. Of the patients for whom a primary renal diagnosis had been reported, renal dysplasia ± reflux was the most common cause of ERF accounting for 34.0% of prevalent cases. There has been growth in treatment numbers in all paediatric renal centres between 1995 and 2010. Whilst the rate of transplantation within 90 days of commencing RRT has remained at around 25-30% of patients, the use of HD has increased by 4% at the expense of PD. CONCLUSIONS: The paediatric ERF population continued to expand with a slow increase in both incidence and prevalence rates. The high incidence in patients from ethnic minority groups will lead to a greater proportion of the population being from these groups in time. To maintain the high proportion of engrafted patients it will be necessary to encourage living donation in the ethnic minority population.

Improvement in the renal prognosis in nephropathic cystinosis.

BACKGROUND AND OBJECTIVES: Nephropathic cystinosis (NC) is an autosomal recessive disorder occurring in one to two per 100,000 newborns. Because of the rarity of NC, long-term outcome data are scarce. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: 245 NC patients from 18 countries provided data to the ESPN/ERA-EDTA registry. We matched NC patients on renal replacement therapy (RRT) to non-NC children on RRT. RESULTS: Between 1979 and 2008, mean age at the start of RRT among NC children increased by 0.15 year per calendar year (95% confidence interval, 0.10 to 0.21) from 8.8 to 12.7 years, whereas we did not observe this in non-NC children. Five-year survival after the start of RRT improved in NC patients from 86.1% (before 1990) to 100% (since 2000) as compared with the control population (89.6% and 94.0%). NC patients received a renal allograft more often (relative risk, 1.09; 95% confidence interval, 1.00 to 1.17) as compared with matched RRT children, and 5-year graft survival was better (94.0% versus 84.0%). NC dialysis patients were less often hypertensive than non-NC children matched for age, country, and dialysis modality (42.7% versus 51.7%) and had lower parathyroid hormone levels (median, 56 versus 140 pg/ml). Although height at start of RRT slightly improved during the past decade, children with NC remained significantly shorter than non-NC children at the start of RRT. CONCLUSIONS: We demonstrated improved survival of the renal function as well as better patient and graft survival after the start of RRT in a large European cohort of NC patients over the last two decades.

Antithymocyte treatment of steroid-resistant acute rejection in renal transplantation.

To evaluate the outcome of early (ER <3 months) and late (LR >3 months) episodes of corticosteroid resistant acute allograft rejection (CRR) treated with anti-thymocyte globulin (ATG) in pediatric renal allograft recipients. Retrospective study of 15 children, mean age 13.2 y, who received ATG for the treatment of biopsy proven CRR over a 15 year period. Seven children received ATG for ER (median 26 days post transplantation) and 8 for LR (median 763 days). There was a significant improvement in the 3 month eGFR (70.3 ml/min/1.73m(2), SD 22.3, p = 0.018) when compared with the value prior to ATG treatment (23.3 ml/min/1.73m(2), SD 10.2) in the ER group. In the LR group (4 DSA positive) there was no improvement in the eGFR at 3 months (42 ml/min/1.73m(2), SD 10.5, p = 0.32) when compared with the value prior to ATG (38 ml/min/1.73 m(2), SD 9.7). At final review, eGFR in the ER group was 72.3 ml/min/1.73m(2) (SD 33) vs. 37.7 ml/min/1.73m(2) (SD 17.9) in the LR group after a mean follow up of 10.4 y and 1.2 y, respectively. ATG therapy in CRR is associated with reversal of rejection and excellent graft outcome in children with ER. The benefits remain uncertain in LR, the etiology of which is multifactorial.

UK Renal Registry 12th Annual Report (December 2009): chapter 14: demography of the UK paediatric renal replacement therapy population in 2008.

AIMS: To describe the demographics of the paediatric RRT population in the UK and analyse changes in demographics with time. METHODS: Extraction and analysis of data from the UK Paediatric Renal Registry and the UK Renal Registry (UKRR). RESULTS: The UK paediatric established renal failure (ERF) population in December 2008 was 905 patients. The prevalence under the age of 16 years was 56 per million age related population (pmarp) and the incidence 7.4 pmarp. The incidence and prevalence for South Asian patients was much higher than that of the White and Black populations. Renal dysplasia was the most common cause of ERF accounting for 33% of prevalent cases. Diseases with autosomal recessive inheritance were a common cause of ERF in all ethnic groups, 23.5% of prevalent and 18% of incident cases. Whilst the incidence and prevalence of diseases with autosomal recessive inheritance in the South Asian population was 3 times that of the white population, this was not the sole reason for the increased proportion of South Asian patients with ERF, as diseases with no defined inheritance were twice as common in this ethnic group than in White patients. Prevalent mortality stood at 9.4%. Most deaths were in patients presenting with ERF early in life and mortality varied markedly according to the aetiology of ERF. The proportion with new grafts from living donors has steadily risen to 54%. Children from ethnic minority groups were less likely to have an allograft and living donation was less frequent in this population. For those on dialysis, 56% were receiving peritoneal dialysis. This was the main treatment modality for patients under 4 years of age. CONCLUSIONS: The paediatric ERF population continued to expand slowly. Incidence and prevalence rates were stable and similar to other developed nations. The high incidence in patients from ethnic minority groups will lead to a greater proportion of the population being from these groups in time. To maintain the high proportion of engrafted patients it will be necessary to encourage living donation in the ethnic minority population. Case note analysis of the factors involved in mortality would be valuable.

Intravenous methylprednisolone in idiopathic childhood nephrotic syndrome.

The aim of our study was to determine the clinical course of children with idiopathic childhood nephrotic syndrome (ICNS) who received intravenous methylprednisolone (ivMP) following failure to achieve remission with standard oral prednisolone therapy. This study was designed as a retrospective case record review from 1993 to 2007. Sixteen children received ivMP over the 15-year study period, of whom ten responded, achieving clinical remission. The remaining six children with steroid resistant nephrotic syndrome (SRNS) underwent biopsy [four focal segmental glomerulosclerosis (FSGS), two minimal change disease (MCD)]. Three responders developed late secondary steroid resistance (two FSGS, one MCD). At the latest follow-up (mean 6.7 years), three of the ten ivMP responders and none (0/6) of the children with SRNS had heavy proteinuria and chronic kidney disease (CKD) stage 3-5. The remaining 13 children demonstrated significant steroid dependency but had achieved stable remission following cyclophosphamide and/or ciclosporin therapy. The majority of children with ICNS who do not respond to 4 weeks of daily prednisolone therapy will enter remission following three to five doses of ivMP, thus avoiding a renal biopsy at initial presentation. These children are likely to develop steroid dependency, and the majority will require treatment with alkylating agents and/or ciclosporin to maintain remission. The requirement for ivMP in this setting appears to be associated with a risk of developing CKD in the longer term.

UK Renal Registry 11th Annual Report (December 2008): Chapter 13 Demography of the UK paediatric renal replacement therapy population.

AIMS: To describe the demographics of the paediatric RRT population in the UK and analyse changes in demographics with time. METHODS: Extraction and analysis of data from the UK paediatric Renal Registry. RESULTS: The UK paediatric established renal failure (ERF) population in April 2008 was 875 patients. The prevalence under the age of 16 years was 55 per million age related population (pmp) and the incidence 7.92 pmp. The incidence and prevalence for South Asian and Other ethnic groups were 3 times that of the White and Black populations. Renal dysplasia was the most common cause of ERF accounting for 33% of prevalent cases. Diseases with autosomal recessive inheritance were more common in patients from ethnic minority groups. The spectrum of diseases seen has changed over a generation. Overall 5 year survival for children with ERF was 91.8%. Five year survival of infants starting dialysis was just 62%. Transplanted patients accounted for 74% of the current population. The proportion with grafts from living donors has steadily risen to 34%. Children from ethnic minority groups were less likely to have an allograft and living donation was less frequent in this population. For those on dialysis, 57% were receiving peritoneal dialysis. This was the main treatment modality for patients under 4 years of age. CONCLUSIONS: The paediatric ERF population continued to expand slowly. Incidence and prevalence rates were stable and similar to other developed nations. The high incidence in patients from ethnic minority groups will lead to a greater proportion of the population being from these groups in time. To maintain the high proportion of engrafted patients it will be necessary to encourage living donation in the ethnic minority population. The spectrum of diseases seen has already changed over a generation with the treatment of young children with diseases such as congenital nephrosis. The incidence of cystinosis causing ERF was reduced, probably reflecting better early treatment.

Demography of renal disease in childhood.

The demography of renal failure in childhood is examined through an analysis of the UK Renal Registry data on patients in established renal failure (ERF) and studies of chronic kidney disease populations. The predominant cause is renal dysplasia and related conditions. Congenital obstructive uropathy is the third largest group overall and the second in early childhood. Males predominate in both these groups. Antenatal diagnoses are frequently not made despite routine scanning. Those children, who present to nephrology after the age of 3 months without an antenatal diagnosis, progress to ERF later than those diagnosed antenatally. Discrepancies exist between the demography of antenatal diagnoses and those seen postnatally. This is likely to represent the limitations of antenatal ultrasound as a diagnostic screening tool.

Successful renal transplantation in children in the presence of thrombosis of the inferior vena cava.

Thrombosis of the inferior vena cava (IVC) has previously been considered to be a contraindication to renal transplantation in children because of the technical difficulties associated with surgery and the increased risk of graft thrombosis. We report three children with previous IVC thrombosis who underwent renal transplantation at our institution over the last 5 years. The pretransplant imaging of these patients included direct venography or magnetic resonance venography to evaluate venous outflow. Two children (19 kg and 36 kg) received deceased donor renal allografts with no surgical complications or delayed graft function. At the latest follow-up 3.0 and 4.6 years posttransplantation, respectively, they were well, with estimated glomerular filtration rates of 52 and 64 ml/min per 1.73 m(2), respectively. The third child underwent a live-related-donor renal transplant at the age of 4.9 years (weight 13.5 kg). There was primary graft nonfunction. Renal vein thrombosis was noted on postoperative day 12, with subsequent graft loss. Children with previous IVC thrombosis can be successfully transplanted with adult-sized kidneys provided detailed evaluation of the venous drainage has been performed. There is substantial risk of graft thrombosis, and detailed counselling regarding the specific risks of the procedure is essential.

Demography and management of childhood established renal failure in the UK (chapter 13).

The incidence and prevalence of ERF in children in the UK are relatively static at 8.0 and 47.7 per million population under the age of 15 years, respectively. The prevalence of ERF in children from the South Asian community is almost three times that of the White population whilst the incidence is over three times that of the White population and similar to the increase seen in the adult population. The high incidence and prevalence are related to the high incidence of inherited diseases which cause ERF in the South Asian community. ERF in children is more common in males than females (male to female ratio 1.54:1). This is due to a preponderance of males with renal dysplasia and obstructive uropathy causing ERF. For the South Asian patients, the gender ratio is 1:1 as the inherited diseases are mainly autosomal recessive. Renal dysplasia is the single most common cause of ERF in childhood, followed closely by glomerular disorders and then obstructive uropathy. The majority of prevalent paediatric ERF patients (76%) have a renal allograft. Of these, 28% are from living donations. The proportion of patients from ethnic minority groups with a functioning allograft is significantly smaller than that in the White population (P < 0.0001). Despite this, the rate of living related donation is no higher in the ethnic minority population. In prevalent patients PD is twice as commonly used as HD with the majority managed with automated PD. For patients at one year from starting RRT, 49% are on PD, 10% on HD and 41% have a transplant.

Outcome of Henoch-Schönlein purpura nephritis treated with long-term immunosuppression.

This retrospective study investigated the outcome of 27 children (19 male) with Henoch-Schönlein purpura nephritis (HSN) of International Study of Kidney Disease in Children (ISKDC) grade 3b or higher treated with long-term immunosuppressive therapy in a single centre over a 10-year period. The mean age at presentation was 9.7 years. The median estimated glomerular filtration rate (eGFR) was 91.3 ml/min per 1.73 m(2), with the median urine protein creatinine ratio (UP:UC) 556 mg/mmol. The treatment protocol comprised daily steroids and cyclophosphamide for 8-12 weeks followed by azathioprine and a reducing regimen of alternate-day steroids for 8-12 months. After a mean follow-up period of 7 years following presentation, 37% made a complete recovery, 40.7% had persistent proteinuria, 7.4% had persistent proteinuria and were on antihypertensive therapy and 14.8% had progressed to end-stage kidney failure (ESKF). Children with poor outcome were older at presentation (p 0.005), had more crescents (p 0.015) and had heavier proteinuria 6 months post initial biopsy (p 0.023). All of the four children with ESKF had nephrotic range proteinuria and greater than 50% crescents on initial biopsy. Despite long-term immunosuppression, the majority of children with HSN grade 3b or higher will have persistent renal abnormalities on long-term follow-up.

Differential effects of low and high dose folic acid on endothelial dysfunction in a murine model of mild hyperhomocysteinaemia.

The exact mechanism(s) by which hyperhomocysteinaemia promotes vascular disease remains unclear. Moreover, recent evidence suggests that the beneficial effect of folic acid on endothelial function is independent of homocysteine-lowering. In the present study the effect of a low (400 microg/70 kg/day) and high (5 mg/70 kg/day) dose folic acid supplement on endothelium-dependent relaxation in the isolated perfused mesenteric bed of heterozygous cystathionine beta-synthase deficient mice was investigated. Elevated total plasma homocysteine and impaired relaxation responses to methacholine were observed in heterozygous mice. In the presence of N(G)-nitro-L-arginine methyl ester relaxation responses in wild-type tissues were reduced, but in heterozygous tissues were abolished. Clotrimazole and 18alpha-glycyrrhetinic acid, both inhibitors of non-nitric oxide/non-prostanoid-induced endothelium-dependent relaxation, reduced responses to methacholine in wild-type but not heterozygous tissues. The combination of N(G)-nitro-L-arginine methyl ester and either clotrimazole or 18alpha-glycyrrhetinic acid completely inhibited relaxation responses in wild-type tissues. Both low and high dose folic acid increased plasma folate, reduced total plasma homocysteine and reversed endothelial dysfunction in heterozygous mice. A greater increase in plasma folate in the high dose group was accompanied by a more significant effect on endothelial function. In the presence of N(G)-nitro-L-arginine methyl ester, a significant residual relaxation response was evident in tissues from low and high dose folic acid treated heterozygous mice. These data suggest that the impaired mesenteric relaxation in heterozygous mice is largely due to loss of the non-nitric oxide/non-prostanoid component. While low dose folic acid may restore this response in a homocysteine-dependent manner, the higher dose has an additional effect on nitric oxide-mediated relaxation that would appear to be independent of homocysteine lowering.

Percutaneous real-time ultrasound-guided renal biopsy by automated biopsy gun in children: safety and complications.

BACKGROUND: Percutaneous renal biopsy under real time ultrasound guidance is a routine procedure in pediatric nephrology and allows a histological diagnosis to be made in children with evidence of renal disease. METHODS: Retrospective case note review. RESULTS: Over four years 191 renal biopsies were attempted in 116 patients; 186 biopsies were performed successfully: 102 native and 84 renal allografts. 151 renal biopsies were performed under sedation and 34 biopsies were performed under general anesthetic, one biopsy without sedation. Problems during sedation were recorded in 5/151 (3.3%) cases. All patients remained in hospital overnight for observation following the biopsy. Complications were reported in 23/185 (12%) of biopsies. Macroscopic hematuria was recorded in 13/185 (7%), presenting within 6-hours of biopsy, on first void, in 11 patients. Two patients developed macroscopic hematuria four and six days after the procedure. One patient with macroscopic hematuria required a single blood transfusion. Three patients developed urinary retention requiring catheterization for up to 48 hours post-procedure, two of whom also had macroscopic hematuria. Pain post procedure was reported in 7.6% episodes and was reported significantly more often with elective native biopsies. CONCLUSIONS: Renal biopsy can safely be performed as a day care procedure, if patients are observed for six hours instead of 24-hours post biopsy.

Platelet nitrate responsiveness in fasting and postprandial type 2 diabetes.

Vascular responsiveness to exogenous nitrates in type 2 diabetes (T2DM) is attenuated in brachial and coronary vessels. We determined platelet responsiveness to nitric oxide (NO) in T2DM and control subjects. We examined whether the postprandial (PP) state affected platelet sensitivity to NO donors in T2DM patients and the extent of correlation between this and measures of oxidative stress, compared to changes in endothelial function. Twelve T2DM subjects were studied fasting and four hours after a test meal and compared with 15 healthy controls. We assessed the inhibitory effects of NO donors on adenosine 5'-diphosphate (ADP)-induced platelet aggregation. Oxidative stress was assessed by lipid-derived free radicals, ex vivo by electron paramagnetic resonance spectroscopy and markers of lipid peroxidation. Endothelial function was assessed by flow-mediated vasodilatation (FMD) of the brachial artery. Results are expressed as (mean +/- SEM). Fasting platelet aggregation was increased in diabetics versus controls (14.86 +/- 1.1 Ohms vs. 10.76 +/- 1.1 Ohms, p < 0.05). Sodium nitroprusside (SNP) and glyceryl trinitrate (GTN) inhibited ADP-induced aggregation by 73.1 +/- 5.9% and 50.3 +/- 7.7% in healthy controls compared to 15.4 +/- 7% and 19.5 +/- 8.2% in T2DM (p < 0.05). Fasting and postprandial inhibition of platelet aggregation with NO donors in T2DM was similar. T2DM patients had higher levels of oxidative stress in the fasting state and postprandially. There were no PP correlations with platelet NO resistance. In conclusion, there is platelet hyporesponsiveness to NO donors (SNP/GTN) in T2DM compared to controls, with increased ADP-induced platelet aggregation. Platelet abnormalities were associated with increased oxidative stress.

Relationship between S-adenosylmethionine, S-adenosylhomocysteine, asymmetric dimethylarginine, and endothelial function in healthy human subjects during experimental hyper- and hypohomocysteinemia.

Experimental hyperhomocysteinemia after an oral methionine or homocysteine load is associated with impaired nitric oxide-dependent vasodilatation in healthy human beings. However, it remains unproven that this effect is mediated by elevations in plasma homocysteine. There is evidence that an increase in plasma homocysteine may increase the formation of asymmetric dimethylarginine (ADMA), an inhibitor of nitric oxide synthase. The methyl groups within ADMA are derived from the conversion of S -adenosylmethionine to S -adenosylhomocysteine intermediates in the methionine/homocysteine pathway. No previous study has assessed the role of methylation status, its impact on ADMA formation, and their association with endothelial function in healthy human beings. In a randomized, placebo-controlled, crossover study, 10 healthy subjects (mean age, 29.1 +/- 3.9 years) were administered an oral dose of methionine (0.1 g/kg), l -homocysteine (0.01 g/kg), N-acetylcysteine (NAC) (0.1 g/kg), or placebo. Endothelial function as assessed by flow-mediated dilatation (FMD) of the brachial artery was impaired after both the methionine and homocysteine load compared with placebo at 4 hours (36 +/- 15, 67 +/- 23 vs 219 +/- 26 microm, respectively, P < .001). N-Acetylcysteine had no effect on flow-mediated dilatation. Plasma total homocysteine was significantly elevated at 4 hours after methionine (23.1 +/- 6.2) and homocysteine (41.5 +/- 8.9) loading, but significantly reduced after NAC 2.4 +/- 0.6 vs 7.1 +/- 2.1 micromol/L in the placebo (P < .001). Plasma S-adenosylmethionine/S-adenosylhomocysteine ratio was significantly (P < .001) increased at 4 hours after methionine (10.9 +/- 0.7) compared with homocysteine (5.4 +/- 0.4), NAC (5.0 +/- 0.3), and placebo (6.0 +/- 0.5). Plasma ADMA concentrations were not altered by any intervention. Our results suggest that endothelial dysfunction due to methionine or homocysteine loading is not associated with an increase in plasma ADMA or a disruption in methylation status.