Parvesh Garg

The VPS33B-binding protein VPS16B is required in megakaryocyte and platelet α-granule biogenesis.

Patients with platelet α or dense δ-granule defects have bleeding problems. Although several proteins are known to be required for δ-granule development, less is known about α-granule biogenesis. Our previous work showed that the BEACH protein NBEAL2 and the Sec1/Munc18 protein VPS33B are required for α-granule biogenesis. Using a yeast two-hybrid screen, mass spectrometry, coimmunoprecipitation, and bioinformatics studies, we identified VPS16B as a VPS33B-binding protein. Immunoblotting confirmed VPS16B expression in various human tissues and cells including megakaryocytes and platelets, and also in megakaryocytic Dami cells. Characterization of platelets from a patient with arthrogryposis, renal dysfunction, and cholestasis (ARC) syndrome containing mutations in C14orf133 encoding VPS16B revealed pale-appearing platelets in blood films and electron microscopy revealed a complete absence of α-granules, whereas δ-granules were observed. Soluble and membrane-bound α-granule proteins were reduced or undetectable, suggesting that both releasable and membrane-bound α-granule constituents were absent. Immunofluorescence microscopy of Dami cells stably expressing GFP-VPS16B revealed that similar to VPS33B, GFP-VPS16B colocalized with markers of the trans-Golgi network, late endosomes and α-granules. We conclude that VPS16B, similar to its binding partner VPS33B, is essential for megakaryocyte and platelet α-granule biogenesis.

Necrotizing Enterocolitis in a mouse model leads to widespread renal inflammation, acute kidney injury and disruption of renal tight junction proteins

Background:Necrotizing enterocolitis (NEC) is a devastating condition affecting premature infants and leads to high mortality and chronic morbidity. Severe form of NEC is associated with acute renal failure, fluid imbalance, hyponatremia, and acidosis. We investigated the effect of NEC on tight junction (TJ) proteins in kidneys using a NEC mouse model to investigate the basis for the observed renal dysfunction.Methods:NEC was induced in C57BL/6 mice by formula feeding and subjecting them to periods of hypoxia and cold stress. NEC was confirmed by gross and histological examination. We studied various markers of inflammation in kidneys and investigated changes in expression of several TJ proteins and AQP2 using immunofluorecent staining and western blotting.Results:We found markedly increased expression of NFκB, TGFβ, and ERK1/2 along with claudin-1, -2, -3, -4, -8, and AQP-2 in NEC kidneys. The membrane localization of claudin-2 was altered in the NEC kidneys and its immunostaining signal at TJ was disrupted.Conclusion:NEC led to a severe inflammatory response not only in the gut but also in the kidneys. NEC increased expression of several TJ proteins and caused disruption of claudin-2 in renal tubules. These observed changes can help explain some of the clinical findings observed in NEC.

Transfusion-associated necrotizing enterocolitis in preterm infants: an updated meta-analysis of observational data

Abstract Background: The number of observational studies that report an association between packed red blood cell (PRBC) transfusions and necrotizing enterocolitis (NEC) has increased. The primary objective of this study was to evaluate the association between PRBC transfusions and NEC in observational studies. Methods: Medline, Embase and Cochrane Library databases as well as the Pediatrics Academic Societies abstract archives were systematically searched to identify observational studies that investigated the association between PRBC transfusions and NEC. Key search terms included premature infant, blood transfusion and necrotizing enterocolitis. The generic inverse variance method with a random-effects model was used to meta-analyze selected studies. Odds ratios (ORs) and confidence intervals (CIs) were calculated. Results: A meta-analysis of 17 observational studies that reported the association between PRBC transfusions and NEC was performed. The meta-analysis revealed no evidence of an association between PRBC transfusions and a higher risk of NEC (OR: 0.96; 95% CI: 0.53–1.71; P=0.88). The effect estimates that suggested an association between PRBC transfusion and NEC in matched case-control studies (OR: 1.20; 95% CI: 0.58–2.47; P=0.63) differed from those reported in cohort studies (OR: 0.51; 95% CI: 0.34–0.75; P=<0.01). Conclusions: This updated meta-analysis of predominantly low-to-moderate quality observational studies suggests that there is no significant association between PRBC transfusions and NEC. A higher quality of evidence on this topic is needed.

Relationship between packed red blood cell transfusion and severe form of necrotizing enterocolitis: A case control study

ObjectiveTo determine if packed red blood cell transfusion is associated with onset of necrotizing enterocolitis, and whether withholding feed has any association with it.MethodsCase records of 100 preterm neonates, (<34 weeks gestation) who developed necrotizing enterocolitis and 99 random age-and gestation-matched controls were evaluated for any blood transfusion 48 h before onset of necrotizing enterocolitis.ResultsDuring the study period 26% infants received packed red blood cell transfusion within 48-hours prior to onset of disease and 84% of these infants were not fed around the time of transfusion. Infants who developed necrotizing enterocolitis after transfusion were older, of lower gestational age, birth weight and more likely to develop stage 3 disease. They had a lower hematocrit at birth and before onset of disease and withholding feeds around transfusion did not prevent necrotizing enterocolitis. Odds of mortality in these infants was 2.83 (95% CI 0.97-8.9) and survivors had no significant difference in incidence of periventricular leukomalacia and length of hospital stay.ConclusionBlood Transfusion associated necrotizing enterocolitis is a severe, mainly surgical form of disease.

Necrotizing Enterocolitis (NEC): A Devastating Disease of Prematurity

Necrotizing Enterocolitis (NEC) is a common and devastating gastrointestinal emergency that primarily affects premature infants. The incidence of necrotizing enterocolitis is 6-10% among infants with birth weight less than 1500 grams. The mortality due to NEC has not improved significantly despite advances in neonatal care and better understanding of clinical and basic sciences. The pathogenesis of NEC is not well understood and several factors such as prematurity, abnormal colonization with pathogenic bacteria, feeding practices, blood transfusion and altered intestinal barrier function may be involved. The clinical presentation of NEC could be sudden and the treatment plan could vary with the stage and type of presentation. Further research is needed to better understand the pathophysiology of NEC and, biomarkers for prediction, prevention and treatment need to be developed. Further clinical trials are needed to determine prevention and treatment modalities for this devastating disease.

Elevated cranial ultrasound resistive indices are associated with improved neurodevelopmental outcomes one year after pediatric cardiac surgery: A single center pilot study

Objective To determine if a non‐invasive, repeatable test can be used to predict neurodevelopmental outcomes in patients with congenital heart disease. Methods This was a prospective study of pediatric patients less than two months of age undergoing congenital heart surgery at the Childrens Health Childrens Medical Center at Dallas. Multichannel near‐infrared spectroscopy (NIRS) was utilized during the surgery, and ultrasound (US) resistive indices (RI) of the major cranial vessels were obtained prior to surgery, immediately post‐operatively, and prior to discharge. Pearsons correlation, Fischer exact t test, and Fischer r to z transformation were used where appropriate. Results A total of 16 patients were enrolled. All had US data. Of the sixteen patients, two died prior to the neurodevelopmental testing, six did not return for the neurodevelopmental testing, and eight patients completed the neurodevelopmental testing. There were no significant correlations between the prior to surgery and prior to discharge US RI and neurodevelopmental outcomes. The immediate post‐operative US RI demonstrated a strong positive correlation with standardized neurodevelopmental outcome measures. We were able to demonstrate qualitative differences using multichannel NIRS during surgery, but experienced significant technical difficulties implementing consistent monitoring. Conclusions A higher resistive index in the major cerebral blood vessels following cardiac surgery in the neonatal period is associated with improved neurological outcomes one year after surgery. Obtaining an ultrasound with resistive indices of the major cerebral vessels prior to and after surgery may yield information that is predictive of neurodevelopmental outcomes.