Donna Rudd

Nephrin - a biomarker of early glomerular injury

Nephrin is a 180 KD trans-membrane protein expressed in glomerular podocytes. It was first identified in children with congenital nephrotic syndrome of the Finnish type (NPHS1). Nephrin forms an integral part of podocytes, which—together with endothelial cells and the basement—form the glomerular filtration barrier. Podocytopathies result in the detection of nephrin in the urine. We reviewed the literature to determine if urine nephrin measurements could become useful as a biomarker to detect early podocyte injury. Our search identified a total of 19 studies that have been published to date. The most common clinical conditions for which urine nephrin analyses were carried out included diabetic nephropathy, glomerulonephritis and pre-eclampsia. Nephrin measurement was carried out using commercially available ELISA kits, the messenger ribonucleic acid real-time polymerase chain Reaction, or electrophoresis. Nephrinuria showed positive correlation with proteinuria and severity of podocyte injury. In two studies, the level of nephrinuria declined in conjunction with clinical improvement in the patient following immunosuppressive treatment. Currently, there is no published data on the value of measuring urinary nephrin in pediatric patients.

Toward a new cold and warm nondepolarizing, normokalemic arrest paradigm for orthotopic heart transplantation

OBJECTIVE Currently, the safe human heart preservation time is limited to around 4 to 5 hours of cold ischemic storage. Longer arrest times can lead to donor heart damage, early graft dysfunction, and chronic rejection. The aim of this study was to examine a new nondepolarizing, normokalemic preservation solution with adenosine and lidocaine for as long as 6 hours of arrest at cold and warmer storage temperatures. METHODS Isolated perfused rat hearts (n = 87) were switched from working to Langendorff (nonworking) mode and arrested at 37 degrees C with 200-micromol/L adenosine and 500-micromol/L lidocaine in Krebs-Henseleit buffer (10-mmol/L glucose, pH 7.7, 37 degrees C) or with Celsior (Sangstat Medical Corp, Fremont, CA). Hearts were removed and placed in static storage at 4 degrees C for 2 and 6 hours or remained on the apparatus and were intermittently flushed at 37 degrees C every 20 minutes for 2 minutes at 68 mm Hg (average arrest temperature 28 degrees -30 degrees C) for 2 and 6 hours. We further investigated the effect of the warmer adenosine-lidocaine solution supplemented with 1- or 5-mmol/L pyruvate. RESULTS Adenosine-lidocaine solution arrested hearts in 16 +/- 2 seconds (n = 32), whereas Celsior did so in 39 +/- 4 seconds (n = 23). After 2 hours of cold static storage, there were no functional differences between the adenosine-lidocaine and Celsior groups, with approximately 70% return of cardiac output. In contrast, after 6 hours of 4 degrees C storage, adenosine-lidocaine hearts had significantly higher functional recoveries (68% +/- 5% cardiac output) than Celsior hearts (47% +/- 14% cardiac output) during 60 minutes of reperfusion. In addition, Celsior hearts took 5 minutes longer to reanimate and showed early reperfusion arrhythmias. At warmer temperatures after 2 hours of arrest, adenosine-lidocaine and Celsior hearts were not significantly different, despite a 43% higher cardiac output in adenosine-lidocaine hearts (80% +/- 3% vs 56% +/- 12%). After 6 hours, adenosine-lidocaine hearts had recovered 55% +/- 3% of prearrest cardiac output, which increased significantly to 75% +/- 4% with addition of 1-mmol/L pyruvate. Adenosine-lidocaine with 1-mmol/L pyruvate hearts spontaneously recovered 106% heart rate, 93% to 105% developed pressures, 70% aortic flow, and 81% coronary flow. Coronary vascular resistance increased 1.7- to 1.9-fold during the 6-hour arrest. In contrast, Celsior hearts did not have return of aortic or coronary flow after 6 hours in these warmer conditions. CONCLUSION A new nondepolarizing, normokalemic adenosine-lidocaine arrest solution in Krebs-Henseleit buffer with 10-mmol/L glucose was versatile at both 4 degrees C and 28 degrees C to 30 degrees C relative to Celsior, and the addition of 1-mmol/L pyruvate significantly improved cardiac output at warmer arrest temperatures. This new arrest paradigm may be useful in the harvest, storage, and implantation of donor hearts.

The association between systemic vascular endothelial growth factor and retinopathy of prematurity in premature infants: a systematic review

Retinopathy of prematurity (ROP), a vasoproliferative disorder exclusive to premature infants is an important cause of childhood blindness. The number of premature infants surviving with this condition is expected to increase globally. Animal models of oxygen-induced retinopathy studies have shown vascular endothelial growth factor (VEGF) to be a key player in the pathogenesis of ROP. This has led to increased use of VEGF antagonist as an alternative treatment for ROP. The purpose of this systematic review is to determine the association between VEGF and ROP in human newborn. The literature review identified 12 studies to date which fulfilled the search criteria. Investigators used cord blood, serum, plasma and tissue samples to investigate the association between ROP and VEGF. Studies that measured VEGF in cord blood found mixed results, with low VEGF (at birth) associated with ROP in one study and no difference noted in two others. Mixed results were also seen in studies determining VEGF in postnatal venous samples. Four studies showed no difference in VEGF level between premature infants with and without ROP, one study showed an increased VEGF level in premature infants with ROP and another study found serum VEGF to be low in premature infants with ROP. The most recent study demonstrated an initial increase in serum VEGF followed by a decline at the time of treatment. These contradictory results indicate that we are yet to fully understand the role of VEGF in human premature infants and question the rationale of treating ROP with anti-VEGF. Anti-VEGF therapy results in systemic effect on serum VEGF levels for up to 2 months and this could have an effect on neurodevelopmental outcome. The effect of this on other developing organs is currently unknown. More studies are required to determine the mechanistic relationships between systemic VEGF and ROP in premature infants.

Early reperfusion with warm, polarizing adenosine–lidocaine cardioplegia improves functional recovery after 6 hours of cold static storage

OBJECTIVE Rewarming and reanimating the donor heart from cold static storage predisposes the organ to injury and graft dysfunction. Our main aim was to investigate the effects of 5 minutes of continuous rewarming with a normokalemic, oxygenated, polarizing adenosine-lidocaine arrest solution after 6 hours of cold static storage (4°C) in adenosine-lidocaine or Celsior (Genzyme Corp, Cambridge, Mass) solutions. METHODS Male Sprague-Dawley rats (350-450 g, n = 40) were randomly assigned to one of 5 groups: (1) adenosine-lidocaine cold arrest with modified Krebs-Henseleit rewarming, (2) adenosine-lidocaine cold arrest with adenosine-lidocaine rewarming, (3) Celsior cold arrest with Celsior rewarming, (4) Celsior cold arrest with Krebs-Henseleit, and (5) Celsior cold arrest with adenosine-lidocaine arrest rewarming. Hearts were perfused in working mode, arrested (37°C), removed and stored for 6 hours at 4°C, reattached in Langendorff mode, and rewarmed for 5 minutes (37°C). Hearts were switched to working mode, and function was compared with prestorage values. Myocardial oxygen consumption and effluent lactate and pH values were measured during rewarming and recovery. RESULTS Cold adenosine-lidocaine hearts rewarmed with Krebs-Henseleit recovered 40% aortic flow and 58% coronary flow at 60 minutes of reperfusion. Rewarming with adenosine-lidocaine arrest solution led to significantly higher aortic flow (63%) and coronary flow (77%) at 60 minutes. Cold Celsior hearts rewarmed with Celsior had 9 times higher effluent lactate values with acidosis (pH 6.5) during the last minute of rewarming compared with all groups, and this was associated with early myocardial, vascular, and electrical stunning. At 5 and 10 minutes of recovery, the aortic flow was 1.0 and 8 mL/min, respectively. If cold Celsior hearts were rewarmed with adenosine-lidocaine, they generated 18-fold higher aortic flow and 16-fold higher coronary flow at 5 minutes. At 60 minutes, cold Celsior with Celsior-rewarmed hearts recovered 35% aortic flow and 50% coronary flow compared with 44% aortic flow and 67% coronary flow (P < .05) for Celsior with adenosine-lidocaine-rewarmed hearts. Celsior with Krebs-Henseleit-rewarmed hearts recovered 39% aortic flow and 51% coronary flow and were not significantly different from Celsior-rewarmed hearts. The myocardial oxygen consumption in the last minute of rewarming was 1.6 times higher for cold adenosine-lidocaine hearts rewarmed with adenosine-lidocaine compared with cold Celsior and Celsior hearts (19 vs 12 μmol O(2)/min/g dry weight) along with low lactate values and no acidosis. CONCLUSIONS Rewarming the rat heart after cold static storage in polarizing adenosine-lidocaine arrest solution resulted in significantly higher aortic flow, coronary flow, and cardiac output compared with that seen after Krebs-Henseleit or Celsior rewarming. Rewarming cold Celsior hearts with adenosine-lidocaine solution reduced stunning. Adenosine-lidocaine cardioplegia might offer a new reperfusion strategy after cold static storage.

Ketogenic diet reverses behavioral abnormalities in an acute NMDA receptor hypofunction model of schizophrenia

[Extract] Recent transcriptomic, proteomic and metabolomics studies suggest that abnormal glucose and energy metabolism may underlie the pathophysiology of schizophrenia (Harris et al., 2013). We hypothesized that interventions that influence energy metabolism might be therapeutically beneficial. One such intervention is the high-fat/low-carbohydrate ketogenic diet (KD) that has been effectively used in drug-resistant epilepsies (Paoli et al., 2013). To test our hypothesis we fed mice with KD for 3 weeks and induced acute NMDA receptor hypofunction by MK-801 (dizocilpine) administration to model the hypo-glutamatergic state that has been hypothesized to contribute to schizophrenia (Amann et al., 2010). We measured psychomotor hyperactivity and stereotyped behavior, social withdrawal and working memory deficits, reflecting the positive, negative and cognitive symptoms of schizophrenia, respectively (Jones et al., 2011).

Intraobserver and interobserver agreement in visual inspection for xanthochromia: implications for subarachnoid hemorrhage diagnosis, computed tomography validation studies, and the Walton rule.

BACKGROUND Visual inspection for xanthochromia is used to diagnose subarachnoid hemorrhage (SAH), to validate computed tomography subarachnoid hemorrhage diagnosis and was used to determine the Walton rule. No study has assessed the reliability of xanthochromia. OBJECTIVE To determine intraobserver and interobserver xanthochromia agreement. METHODS Mock cerebrospinal fluid samples contained increasing concentrations of human oxyhemoglobin, bilirubin, and albumin. Non-color-blind observers randomly assessed samples against a white background twice under significantly differing illumination. Specimens were recorded as red, orange, yellow, or clear. RESULTS Results were obtained for 26 observers (11 male, 15 female observers). We found that 19.2% of samples were misclassified: red, 11.7%; orange, 28.5%; yellow, 29.6%; and clear, 22.1% (χ = 213.2; P < .001). Of the yellow misclassifications, 88% were misclassified as clear. Female observers correctly classified samples significantly more frequently than male observers (P = .03). Intraobserver agreement differed significantly from expected for both male (χ = 105.6; P < .001) and female (χ = 99.9; P < .001) observers regardless of illumination. Interobserver agreement was poor regardless of sex (χ for male observers = 176.96, P < .001; χ for female observers = 182.69, P < .001) or illumination (χ for bright = 125.64, P < .001; χ for dark = 148.48, P < .001). Overall, there was 75% agreement in 46% of the tests and 90% agreement in only 36% of the tests. CONCLUSION This simple laboratory study would be expected to maximize agreement relative to clinical practice. Although non-color-blind female observers significantly outperformed non-color-blind male observers, both intraobserver agreement and interobserver agreement for xanthochromia were prohibitively poor regardless of sex or illumination. Yellow was most frequently misclassified, 88% as clear (ie, true positives were commuted to false negatives). Xanthochromia is therefore highly unreliable for subarachnoid hemorrhage diagnosis and computed tomography validation. The Walton rule requires urgent clinical revalidation.

Evaluation of fetal kidney growth using ultrasound: a systematic review

PURPOSE To determine the role of ultrasound imaging in evaluating fetal kidney growth. METHODS MEDLINE, CINAHL and EMBASE databases were electronically searched for studies between 1996 and January 2017 and limited to English language. Studies were included if they reported on an ultrasound technique to assess fetal kidney growth and they were not a case report or case series. There was independent selection of studies by two reviewers in consensus with one other reviewer. Data were extracted by one reviewer in consensus with two other reviewers. RESULTS A total of 1785 articles were identified. The full text of 39 of these were assessed for eligibility for inclusion. Twenty-eight studies were then included in the review. Standard two dimensional (2D) fetal renal measurements are easy to perform, however, this review identified that most studies had some methodological limitations. The disadvantage with 2D and three dimensional (3D) fetal renal volumes are that they include the entire kidney and good reproducibility of 3D volumes has not yet been demonstrated. Currently there is limited research on fetal kidney growth in the setting of abnormal fetal growth. Research focussing directly on fetal kidney parenchyma and blood flow is scarce. CONCLUSIONS Some nomograms of 2D and 3D fetal kidney size and volume have been developed. Kidney length is the most popular single fetal kidney measurement; however, it does not seem to be a good indicator of growth. In IUGR fetuses, kidney length remained similar to appropriately grown fetuses whereas AP and TS dimensions were significantly decreased. New ultrasound techniques focusing on the parenchyma of the kidney and perfusion to the kidney should be explored as they may provide more meaningful information on kidney development in the fetus and future kidney function.

Biomarker of Early Glomerular Injury in Pre-eclampsia.

Objectives: Nephrin is an integral part of podocytes that together with endothelial cells and the basement form the glomerular filtration barrier. Placental ischemia triggers a cascade of events that ultimately result in endothelial malfunction, hypertension, podocytopathy and fetal compromise. Methods: We review the literature to determine if urine nephrin measurements could serve as a useful biomarker to detect early podocyte injury in pre-eclampsia. Results: Our search identifies eight studies published to date. The findings of these studies demonstrate that urine nephrin excretion plays a critical role in the pathogenesis of proteinuria during pre-eclampsia and that this is a good indicator of glomerular injury. Conclusion: There is thus an urgent need for a large multi-centre clinical study using standardized recruitment criteria to determine the full potential of this biomarker in clinical practice.

Development of a diet-induced murine model of diabetes featuring cardinal metabolic and pathophysiological abnormalities of type 2 diabetes

ABSTRACT The persistent rise in global incidence of type 2 diabetes (T2D) continues to have significant public health and economic implications. The availability of relevant animal models of T2D is critical to elucidating the complexity of the pathogenic mechanisms underlying this disease and the implications this has on susceptibility to T2D complications. Whilst many high-fat diet-induced rodent models of obesity and diabetes exist, growing appreciation of the contribution of high glycaemic index diets on the development of hyperglycaemia and insulin resistance highlight the requirement for animal models that more closely represent global dietary patterns reflective of modern society. To that end, we sought to develop and validate a murine model of T2D based on consumption of an energy-dense diet containing moderate levels of fat and a high glycaemic index to better reflect the aetiopathogenesis of T2D. Male C57BL/6 mice were fed an energy-dense (ED) diet and the development of pathological features used in the clinical diagnosis of T2D was assessed over a 30-week period. Compared with control mice, 87% of mice fed an ED diet developed pathognomonic signs of T2D including glucose intolerance, hyperglycaemia, glycosylated haemoglobin (HbA1c) and glycosuria within 30 weeks. Furthermore, dyslipidaemia, chronic inflammation, alterations in circulating leucocytes and renal impairment were also evident in ED diet-fed mice compared with mice receiving standard rodent chow. Longitudinal profiling of metabolic and biochemical parameters provide support of an aetiologically and clinically relevant model of T2D that will serve as a valuable tool for mechanistic and therapeutic studies investigating the pathogenic complications of T2D. Summary: We describe a murine model of type 2 diabetes based on chronic consumption of an energy-dense diet. Longitudinal sampling demonstrates metabolic and pathological changes closely simulating progression to overt diabetes.

Female Preterm Indigenous Australian Infants have lower renal volumes than males; a predisposing factor for end-stage renal disease?: Ethnicity, prematurity, gender and renal diseases

Indigenous Australians have an increased risk of developing chronic kidney disease (CKD). Indigenous women have a higher rate of CKD than men. In a cohort of Indigenous and non‐Indigenous preterm neonates, we assessed total renal volume (TRV) (a proxy indicator for nephron number). We hypothesized that there would be no difference in renal volume between these two groups at term corrected (37 weeks gestation).