Disruption of Urate Transport in Familial Renal Glucosuria and Report on SGLT2 Expression in Normal and Pathological Kidney

Familial renal glucosuria (FRG) is a rare co -dominantly inherited benign phenotype characterized by the presence of glucose in the urine. It is caused by mutations in the SLC5A2 gene that encodes SGLT2, a Na+ -glucose co -transporter. The purpose of our current work was twofold: to characterize the molecular and phenotype findings of an FRG cohort and, in addition, to detail the SGLT2 expression in the adult human kidney. The phenotype of FRG pedigrees was evaluated using direct sequencing for the identification of sequence variations in the SLC5A2 gene. The expression of SGLT2 in the adult human kidney was studied by immunofluorescence on kidney biopsy specimens. In the absence of renal biopsies from FRG individuals, and in order to evaluate the potential disruption of SGLT2 expression in a glucosuric nephropathy, we have selected cases of nucleoside analogues induced proximal tubular toxicity. We identified six novel SLC5A2 mutations in six FRG pedigrees and described the occurrence of hyperuricosuria associated with hypouricaemia in the two probands with the most severe phenotypes. Histopathological studies proved that SGLT2 is localized to the brush -border of the proximal tubular epithelia cell and that this normal pattern was found to be disrupted in cases of nucleoside analogues induced tubulopathy. We present six novel SLC5A2 mutations, further contributing to the allelic heterogeneity in FRG, and identified hyperuricosuria and hypouricaemia as part of the FRG phenotype. SGLT2 is localized to the brush -border of the proximal tubule in the adult human normal kidney, and aberrant expression of the co -transporter may underlie the glucosuria seen with the use of nucleoside analogues.

Chronic Allograft Dysfunction - Is There a Treatment?

BACKGROUND: The major causes of renal transplant loss are death and chronic allograft dysfunction (CAD). The aims of this study were to determine the incidence of CAD in our population and the relation between allograft survival and immunosuppressive regimens. METHODS: We studied retrospectively 473 patients who received deceased donor kidney transplants with at least 1 allograft biopsy between January 1990 and May 2007. Clinical data included age, gender, biopsy data, and immunosuppression before and after kidney biopsy. Mean age was 45.4 +/- 12.7 years including 65% males with a mean follow-up of 6.7 +/- 4.5 years. CAD was observed in 177 of 473 biopsies: 48 patients showed interstitial fibrosis (IF); 101 chronic rejection (CR); 16 transplant glomerulopathy (TG); and 12, CR and TG. Mean follow-up since the discovery of the histologic feature was 60.5 +/- 50.5 months for IF; 38.3 +/- 40.8 for CR, and 18.2 +/- 19.2 for TG. RESULTS: CAD, which was more common in younger patients (P = .03), correlated upon univariate and multivariate analysis with CKD stage 5d development (P < .001). Deposition of C4d in peritubular capillaries was more frequent among CAD patients (P = .004), an association with particular relevance to recipients with CR (P = .02) and TG (P < .001). When we analyzed CAD subpopulation, we observed a positive correlation between allograft survival and immunosuppression modification after biopsy. Substitution of sirolimus (40/177) was shown in univariate, multivariate and Cox regression analyses to be a renal protector (P < .002). Allograft survival was also correlated with initial mycophenolate mofetil versus azathioprine, (62/177) immunosuppression (P < .001). CONCLUSION: CAD, a frequent histologic feature, may benefit from sirolimus conversion.

Specificity and Sensitivity of Screening for Anti-HLA Antibodies in Kidney Allograft Dysfunction

BACKGROUND: Prospective testing for posttransplant circulating anti-HLA antibodies seems to be a critical noninvasive tool, but confirmatory data are lacking. MATERIALS AND METHODS: Over the last 3 years, peritubular capillary (PTC) C4d deposition was prospectively sought by an immunofluorescence technique applied to frozen tissue in biopsies obtained for allograft dysfunction. Screening for circulating anti-HLA class I/II alloantibodies (AlloAb) by the flow cytometric test was performed simultaneously. RESULTS: We evaluated 132 sets of biopsies and simultaneous serum samples. PTC C4d deposition was demonstrated in 15.9% (21/132) of biopsies. Circulating anti-HLA I/II AlloAb were detected in 25% (33/132) of serum samples. Employing receiver-operator characteristic (ROC) curves for all C4d-positive biopsies, screening for AlloAb showed a global specificity of 82% and sensitivity of 61.9%. When this analysis was restricted to biopsies obtained in the first month posttransplantation, the sensitivity increased to 81.8%, but the specificity decreased to 76.9%. After the first month posttransplantation, we observed sensitivity of 40.0% and a specificity of 86.4%. In the first month posttransplantation, all patients with a diagnosis of acute antibody-mediated rejection displayed circulating anti-HLA class I/II, but not always at the same time as the C4d-positive biopsy. CONCLUSIONS: In the first month posttransplantation, prospective monitoring of anti-HLA antibodies may be useful. The high sensitivity allows the identification of patients at risk, affording an earlier diagnosis of antibody-mediated rejection. After the first month, the test can be used to evaluate allograft dysfunction episodes, since positivity is highly suggestive of an antibody-mediated process.

Impact of Renal Dysfunction on Liver Transplantation: a Retrospective Study in 708 Orthotopic Liver Transplant Recipients

Renal dysfunction often complicates the course of orthotopic liver transplant recipients and is associated with increased morbid -mortality. The aims of this study were to determine the incidence of chronic renal disease and its impact on patient survival. Clinical data included age, gender and weight,aetiology of hepatic failure, presence of diabetes,hypertension, hepatitis B and C infection, renal dysfunction pretransplant and immunosuppression. Laboratory data included serum creatinine at days 1, 7, 21, month 6, 12 and yearly. The glomerular filtration rate was determined by Cockcroft-Gault equation. We studied retrospectively from September 1992 to March 2007 708 orthotopic liver transplant recipients. Mean age 44±12.6 years, 64% males, 17% diabetic, 18.8% hypertensive, 19.9% with hepatitis C and 3.8% hepatitis B. Renal dysfunction pretransplant was known in 21.6%. Mean follow-up was 3.6 years. Mean transplant survival 75% at 12 months. 154 patients died. Univariate and multivariate analyses were performed and a p<0.05 was considered significant. Acute kidney injury occurred in 33.2%. Chronic kidney disease stage 3 was observed in 34.3%,stage 4 in 6.2% and stage 5 in 5.1%. At the time of this study, 46.4% were on Cyclosporine A, 44.7% on tacrolimus and 8.9% on sirolimus. Using multivariate analysis, renal dysfunction was correlated with renal dysfunction pre -orthotopic liver transplant (p<0.001), acute kidney injury (p<0.001), haemodialysis development (p<0.001), and inversely correlated with the use of mycophenolate mophetil (p<0.001); mortality was positively correlated with renal dysfunction pretransplant (p=0.03),chronic kidney disease stage 4 (p=0.001), chronic kidney disease stage 5 (p<0.001) and inversely correlated with the use of tacrolimus (p=0.006). In conclusion orthotopic liver transplant recipients are disposed to renal complications that have a negative impact on survival of these patients.

Peritubular Capillaries C4d Deposits in Renal Allograft Biopsies and Anti HLA I/II Alloantibodies Screening. Incidence and Clinical Importance

Aim: To characterise clinically the patients with C4d in peritubular capillaries deposits (C4dPTCD) and/or circulating anti-HLA class I/II alloantibodies. To determine the correlation between positive C4dPTCD and circulating anti-HLA class I/II alloantibodies during episodes of graft dysfunction. Subjects and Methods: C4d staining was performed in biopsies with available frozen tissue obtained between January 2004 and December 2006. The study was prospective from March 2005, when a serum sample was obtained at the time of biopsy to detect circulating anti-HLA class I/II alloantibodies. Results: We studied 109 biopsies in 86 cadaver renal transplant patients. Sixteen of these (14.7%) presented diffuse positive C4dPTCD. There was a 13.5% rate of +C4dPTCD incidence within the first six months of transplantation and 16% after six months (p>0.05). Half of the +C4dPTCD in the first six months was associated with acute humoral rejection. After six months, the majority of +C4dPTCD (n=7/8) was present in biopsies with evidence of interstitial fibrosis/tubular atrophy and/or transplant glomerulopathy. The C4dPTCD was more frequent in patients with positive anti-HCV antibodies(p<0.0001), a previous renal transplant (p=0.007), and with a panel reactivity antibody (PRA) ≥ 50%(p=0.0098). The anti-HCV+ patients had longer time on dialysis (p=0.0019) and higher PRA(p=0.005). Circulating anti-HLA I/II alloantibodies were screened in 46 serum samples. They were positive in 10.9% of samples, all obtained after six months post transplant. Circulating alloantibodies were absent in 92.5% of the C4d negative biopsies. Conclusion: We found an association between the presence of C4dPTCD and 2nd transplant recipients,higher PRA and the presence of anti-HCV antibodies. The presence of HCV antibodies is not a risk factor for C4dPTCD per se, but appears to reflect longer time on dialysis and presensitisation. In renal dysfunction a negative alloantibody screening is associated with a reduced risk of C4dPTCD (<10%).

C4d Detection in Renal Allograft Biopsies: Immunohistochemistry vs. Immunofluorescence

Introduction. Peritubular capillary complement 4d staining is one of the criteria for the diagnosis of antibody-mediated rejection, and research into this is essential to kidney allograft evaluation. The immunofluorescence technique applied to frozen sections is the present gold-standard method for complement 4d staining and is used routinely in our laboratory. The immunohistochemistry technique applied to paraffin-embedded tissue may be used when no frozen tissue is available. Material and Methods. The aim of this study is to evaluate the sensitivity and specificity of immunohistochemistry compared with immunofluorescence. We describe the advantages and disadvantages of the immunohistochemistry vs. the immunofluorescence technique. For this purpose complement 4d staining was performed retrospectively by the two methods in indication biopsies (n=143) and graded using the Banff 07 classification. Results. There was total classification agreement between methods in 87.4% (125/143) of cases. However, immunohistochemistry staining caused more difficulties in interpretation, due to nonspecific staining in tubular cells and surrounding interstitium. All cases negative by immunofluorescence were also negative by immunohistochemistry. The biopsies were classified as positive in 44.7% (64/143) of cases performed by immunofluorescence vs. 36.4% (52/143) performed by immunohistochemistry. Fewer biopsies were classified as positive diffuse in the immunohistochemistry group(25.1% vs. 31.4%) and more as positive focal (13.2% vs. 11.1%). More cases were classified as negative by immunohistochemistry (63.6% vs. 55.2%). Study by ROC curve showed immunohistochemistry has a specificity of 100% and a sensitivity of 81.2% in relation to immunofluorescence (AUC: 0.906; 95% confidence interval: 0.846-0.949; p=0.0001). Conclusions. The immunohistochemistry method presents an excellent specificity but lower sensitivity to C4d detection in allograft dysfunction. The evaluation is more difficult, requiring a more experienced observer than the immunofluorescence method. Based on these results, we conclude that the immunohistochemistry technique can safely be used when immunofluorescence is not available.

N170 Asymmetry as an Index of Inferior Occipital Dysfunction in Patients With Symptomatic Occipital Lobe Epilepsy

Objective: Localizing epileptic foci in posterior brain epilepsy remains a difficult exercise in surgery for epilepsy evaluation. Neither clinical manifestations, neurological, EEG nor neuropsychological evaluations provide strong information about the area of onset, and fast spread of paroxysms often produces mixed features of occipital, temporal and parietal symptoms. We investigated the usefulness of the N170 event-related potential to map epileptic activity in these patients. Methods: A group of seven patients with symptomatic posterior cortex epilepsy were submitted to a high-resolution EEG (78 electrodes), with recordings of interictal spikes and face-evoked N170. Generators of spikes and N170 were localized by source analysis. Range of normal N170 asymmetry was determined in 30 healthy volunteers. Results: In 3 out of 7 patients the N170 inter-hemispheric asymmetry was outside control values. Those were the patients whose spike sources were nearest (within 3 cm) to the fusiform gyrus, while foci further away did not affect the N170 ratio. Conclusions: N170 event-related potential provides useful information about focal cortical dysfunction produced by epileptic foci located in the close neighborhood of the fusiform gyrus, but are unaffected by foci further away. Significance: The N170 evoked by faces can improve the epileptic foci localization in posterior brain epilepsy.

Acidose Tubular Renal Distal e Surdez Neurossensorial com Mutação no Gene ATP6V1B1

A acidose tubular renal distal é uma doença rara, caracterizada pela incapacidade na acidificação da urina, condicionando acidose metabólica hiperclorémica, hipocaliémia, hipercalciúria e nefrocalcinose, o que poderá causar atraso de crescimento, alteração do metabolismo ósseo e insuficiência renal crónica. A acidose tubular renal distal associada a surdez neurossensorial é uma doença de herança autossómica recessiva, causada por mutações do gene que codifica a subunidade B1 da H+ -ATPase (ATP6V1B1). Os autores relatam os casos de duas irmãs que apresentaram má progressão ponderal, alterações iónicas, do equilíbrio ácido base e surdez neurossensorial. Foi detectada em ambas as crianças a mutação homozigótica no gene ATP6V1B1. Com estes dois casos pretende -se destacar a importância de um diagnóstico precoce nesta patologia rara.

Neuropsychological Abnormalities in Children with the Panayiotopoulos Syndrome Point to Parietal Lobe Dysfunction

Panayiotopoulos syndrome (PS) is a common epilepsy syndrome associated with rare clinical seizures and unknown localization of the epileptogenic area. Despite findings of normal development in patientswith PS, recent neuropsychological studies point to subtle and diverse cognitive impairments. No well-outlined hypothesis about the localization of the brain dysfunction responsible for these impairments has been proposed.We further explored the cognitive dysfunctions in PS andmade inferences on the most likely anatomical localization of brain impairment. A group of 19 patients (aged 6–12) with PS was rated according to spike activity and lateralization. The patients were submitted to a neuropsychological evaluation to assess general intelligence, memory, language, visual–perceptual abilities, attention, and executive functions. Using 35-channel scalp EEG recordings, the N170 face-evoked event-related potential (ERP)was obtained to assess the functional integrity of the ventral pathway. All patientswith PS showed normal IQ but subtle and consistent neurocognitive impairments. Namely, we found abnormalities in the copy task of the Rey–Osterrieth Complex Figure and in theNarrative Memory Test. There was no correlation between neuropsychological impairments with spike activity and hemispheric spike lateralization. The N170 ERP was normal in all patients except for one. Our neuropsychological findings demonstrate impairments in visual–perceptual abilities and in semantic processing. These findings, paired with the absence of occipital lobe dysfunction in all neuropsychological studies of PS performed to this date, support the existence of parietal lobe dysfunction.

Fratura Proximal do Fémur Bilateral. Incidência e Fatores de Risco de Fratura Contralateral

Nos doentes com fratura osteoporótica da extremidade proximal do fémur, pouco é conhecido sobre a incidência e fatores de risco de fratura contralateral da extremidade proximal do fémur. O objetivo deste trabalho foi, através de um estudo retrospetivo determinar a incidência e os fatores de risco para fratura bilateral da extremidade proximal do fémur não contemporânea. Foram analisados os processos de 1911 doentes com fratura da extremidade proximal do fémur entre 2003 e 2009. Os dados recolhidos sobre as fraturas, tratamentos e comorbilidades foram trabalhados estatisticamente. Um total de 64 doentes (3,24%) teve fratura bilateral da extremidade proximal do fémur, com uma média de idades acima dos 80 anos. Determinou-se que existe uma relação direta entre o tipo da primeira e segunda fratura (intracapsular vs extraapsular), e que 70% das segundas fraturas ocorrem nos primeiros três anos após fratura. Das comorbilidades verificou-se que a doença de Parkinson, Hipertensão Arterial, doença Cardíaca, Anemia e alterações da Visão representam um risco acrescido para fratura contralateral da extremidade proximal do fémur. Propomos um follow-up mais rigoroso nos primeiros três anos após a primeira fratura e estabelecidas melhores formas de prevenção de fraturas e otimização das comorbilidades nos doentes com fatores de risco.

Mid-Term Results of EVAR in Severe Proximal Aneurysm Neck Angulation.

OBJECTIVE: To determine if mid-term outcome following endovascular aneurysm repair (EVAR) with the Endurant Stent Graft (Medtronic, Santa Rosa, CA, USA) is influenced by severe proximal neck angulation. METHODS: A retrospective case-control study was performed using data from a prospective multicenter database. All measurements were obtained using dedicated reconstruction software and center-lumen line reconstruction. Patients with neck length >15 mm, infrarenal angle (β) >75°, and/or suprarenal angle (α) >60°, or neck length >10 mm with β >60°, and/or α >45° were compared with a matched control group. Primary endpoint was primary clinical success. Secondary endpoints were freedom from rupture, type 1A endoleak, stent fractures, freedom from neck-related reinterventions, and aneurysm-related adverse events. Morphological neck variation over time was also assessed. RESULTS: Forty-five patients were included in the study group and were compared with a matched control group with 65 patients. Median follow-up time was 49.5 months (range 30.5-58.4). The 4-year primary clinical success estimates were 83% and 80% for the angulated and nonangulated groups (p = .42). Proximal neck angulation did not affect primary clinical success in a multivariate model (hazard ratio 1.56, 95% confidence interval 0.55-4.41). Groups did not differ significantly in regard to freedom from rupture (p = .79), freedom from type 1A endoleak (p = .79), freedom from neck-related adverse events (p = .68), and neck-related reinterventions (p = .68). Neck angle reduction was more pronounced in patients with severe proximal neck angulation (mean Δα -15.6°, mean Δβ -30.6°) than in the control group (mean Δα -0.39°, mean Δβ -5.9°) (p < .001). CONCLUSION: Mid-term outcomes following EVAR with the Endurant Stent Graft were not influenced by severe proximal neck angulation in our population. Despite the conformability of the device, moderate aortic neck remodeling was identified in the group of patients with angulated neck anatomy on the first computed tomography scan after implantation with no important further remodeling afterwards. No device integrity failures were encountered.