Interaction of the leucine-rich repeats of polycystin-1 with extracellular matrix proteins: possible role in cell proliferation.

Polycystin-1, the product of the PKD1 gene, is a membrane-bound multidomain protein with a unique structure and a molecular weight of approximately 460 kD. The purpose of this study is to investigate the binding of the cystein-flanked leucine-rich repeats (LRR) of polycystin-1 to extracellular matrix (ECM) components. These interactions may play a role in normal renal development as well as the pathogenesis of autosomal-dominant polycystic kidney disease (ADPKD). In vitro assays were used to assess the binding of a fusion protein containing the LRR of polycystin-1 and that of affinity purified polycystin-1 to a number of ECM components. The results showed that the LRR modulate the binding of polycystin-1 to collagen I, fibronectin, laminin, and cyst fluid-derived laminin fragments. The addition of the LRR fusion protein to cells in culture resulted in a significant dose-dependent reduction in the rate of proliferation. Cyst fluid-derived laminin fragments had a stimulatory effect on cell proliferation, which was reversed by the LRR fusion protein. These results suggest that the LRR of polycystin-1 act as mediators of the polycystin-1 interaction with the ECM. The observed suppression effect of the LRR on cell proliferation suggests a functional role of the LRR-mediated polycystin-1 involvement in cell-matrix and cell-cell interactions. These interactions may result in the enhanced cell proliferation that is a characteristic feature of ADPKD.     

Comparison of 2-dimensional and 3-dimensional acquisition for 18F-FDG PET oncology studies performed on an LSO-based scanner.

Three-dimensional (3D) PET acquisition has the potential to reduce image noise but the advantage of 3D PET for studies outside the brain has not been well established. To compare the performance of 2-dimensional (2D) and 3D acquisition for whole-body (18)F-FDG applications, a series of patient studies were performed using a lutetium oxyorthosilicate (LSO)-based tomograph. METHODS: Comparative 2D and 3D images were acquired for 27 oncology patients using an LSO-based tomograph. Data acquisition (350-650 keV, 6 ns) started 99 +/- 12 min (mean +/- SD) after injection of 624 +/- 76 MBq (18)F-FDG. Bias caused by tracer redistribution and decay was eliminated by acquiring dynamic data over a single-bed position using a protocol that alternated between septa-in and septa-out modes (2D, 3D, 2D, 3D, 2D, 3D). Frames were combined to form 8 statistically independent sinograms: four 2D replicates (105 s) and four 3D replicates (90 s). The different frame durations in 2D and 3D compensated for the different number of overlapping bed positions required for an 85-cm whole-body study. Images were reconstructed with either 2D or fully 3D ordered-subsets expectation maximization (2 iterations and 8 subsets; 2D 6-mm gaussian, 3D 5- and 6-mm gaussian). Image target-to-background ratio was assessed by dividing the lesion maximum by the mean within a neighboring background region. Image noise was assessed by applying background regions of interest to the replicate images and calculating the within-patient coefficient of variation. RESULTS: The difference in target-to-background ratio between the 2D and 3D images, when they were filtered with 6-mm and 5-mm gaussian filters, respectively, was not highly statistically significant (P = 0.16). The mean ratio of 3D to 2D image values was 0.94 with 95% limits of agreement of 0.63-1.41. The within-patient coefficients of variation for the 2D and 3D images were 13% +/- 15% and 9% +/- 10%, respectively (P = 0.0005). CONCLUSION: Under conditions of matched target to-to-background ratios, the 3D mode was found to produce images with significantly less variability than the 2D mode. These data provide support for the use of 3D acquisition with LSO detectors to reduce scan times in whole-body (18)F-FDG applications.     

Long and short-term outcomes in patients requiring continuous renal replacement therapy post cardiopulmonary bypass.

OBJECTIVE: The development of acute renal failure following cardiac surgery is a rare but devastating complication with high morbidity and mortality. This study aimed to assess the incidence of acute renal failure necessitating continuous renal replacement therapy (CRRT) in patients who required cardiopulmonary bypass, to determine the factors associated with mortality and to evaluate long-term outcome. METHODS: Patients who underwent cardiac surgery between October 1997 and 2003 and treated with CRRT were included (n=98). Six patients were then excluded (already in established renal failure pre-operatively) and one patient lost to follow-up. A retrospective analysis was carried out. RESULTS: Overall CRRT was used in 2.9% (92/3172). The mean (SD) age of patients was 68 (10) years. Their mean pre-operative creatinine level and duration of cardiopulmonary bypass were 154 (87)micromol/l and 160 (84)min, respectively. Mean duration from surgery to establishment of CRRT was 50 (42)h. Mean creatinine level prior to hospital discharge was 168 (93)micromol/l. Thirty-day mortality was 42%. Significant risk factors for death were complex procedures (odds ratio=9.9), gastro-intestinal complications (OR=7.2), cross-clamp time over 88min (OR=5.9), re-exploration (OR=4.0) and patients age over 75 years (OR=3.3). Actuarial 1 and 5-year survivals (95% CI) were 53 (43, 63) % and 52 (42, 62) %, respectively. Only 2 (2.2%) patients required long term renal support. CONCLUSIONS: Acute renal failure necessitating the use of CRRT is a rare but serious complication post cardiopulmonary bypass. In the long-term, surviving patients are not likely to require further renal support.     

Case series: Combined spinal epidural anesthesia for Cesarean delivery andex utero intrapartum treatment procedure

PURPOSE: To report the use of regional anesthesia and iv nitroglycerin to provide anesthesia and uterine relaxation for three Cesarean deliveries (CD) involving ex utero intrapartum treatment (EXIT) of potentially life-threatening airway obstruction in the newborn. CLINICAL FEATURES: Case 1--a 36-yr-old woman at 38 weeks' gestation was scheduled for an elective CD for fetal skeletal dysplasia and micrognathia. Case 2--a 34-yr-old woman at 35 weeks gestation had a fetal ultrasound revealing fixed neck flexion and micrognathia consistent with fetal arthrogryposis. Case 3--a 27-yr-old woman presented at 38 weeks gestation for CD for severe fetal micrognathia, with mandibular growth below the fifth percentile. For each case, a combined spinal epidural anesthetic was performed with 0.75% bupivacaine, fentanyl and morphine intrathecally followed by placement of a multiorifice epidural catheter. Prior to uterine incision patients received a loading dose followed by an iv infusion of nitroglycerin. Uterine relaxation was sufficient in all cases for delivery of the fetus, and allowed for evaluation by direct laryngoscopy and intubation while maintaining fetal-placental circulation. The surgical procedures were completed without incident. CONCLUSIONS: Anesthesia and uterine relaxation for CD and EXIT procedures can be safely provided with regional anesthesia and iv nitroglycerin.     

Promutagenic methylation damage in bladder DNA from patients with bladder cancer associated with schistosomiasis and from normal individuals.

Radioimmunoassays (RIAs) have been used to detect the promutagenic lesion O6-methyldeoxyguanosine (O6-MedG) in DNA isolated from the bladder tissues of Egyptian patients presenting with bladder carcinoma and concomitant schistosomiasis (bilharziasis), a parasitic disease known to be associated with the presence of N-nitrosamines in the urine. Alkylation damage was present in the DNA of the majority of the samples (44/46, 96%); 38 samples were of tumour tissue and 8 from uninvolved bladder mucosa. Levels of O6-MedG ranged from undetectable (ND; i.e. less than 0.01 mumol O6-MedG/mol dG) to 0.485 mumol/mol dG with an overall mean of 0.134 +/- 0.10 mumol/mol dG, including the two samples that were below the limit of detection. In contrast, methylation damage was detected in only 4/12 (33%) of the DNA samples from normal bladder tissue of European origin. In these samples levels of O6-MedG ranged from ND to 0.225 mumol/mol dG with an overall mean of 0.046 +/- 0.082 mumol O6-MedG/mol dG. These results confirm that alkylation events can be detected in the DNA of schistosome-infected human bladder tissue. The methylation of uninvolved and tumour tissue DNA to similar extents suggests that the alkylating intermediate may have been present in the urine. These results indicate the need for further investigation to determine whether relationships exist between levels of DNA damage and the prevalence of schistosome infection and/or the extent and type of bacterial infection that frequently accompanies this disease.     

Release of Proinflammatory Cytokines During Pediatric Cardiopulmonary Bypass: Heparin-Bonded Versus Nonbonded Oxygenators

Background. Heparin bonding of the cardiopulmonary bypass (CPB) circuit may be associated with a reduced inflammatory response and improved clinical outcome. The relative contribution of a heparin-bonded oxygenator (ie, >80% of circuit surface area) to these effects was assessed in a group of pediatric patients.

Methods. Twenty-one pediatric patients undergoing CPB operations were assigned randomly to receive either a heparin-bonded oxygenator (group H, n = 11) or a nonbonded oxygenator (group C, n = 10) in otherwise nonbonded circuits. The two groups were similar in pathology, age, weight, CPB time, and cross-clamp time. Plasma levels of the cytokines tumor necrosis factor-, interleukin-6, and interleukin-8, as well as terminal complement complex, neutrophils, and elastase, were analyzed before, during, and after CPB.

Results. Significant levels of tumor necrosis factor- were not detected in either group. Plasma levels of all other markers increased during and after CPB compared with baseline. Plasma levels of interleukin-6 peaked in both groups 2 hours after the administration of protamine but remained significantly higher in group C 24 hours after operation. Plasma concentrations of interleukin-8 peaked at similar levels in both groups 30 minutes after protamine administration and returned to baseline thereafter. Levels of terminal complement complex and elastase peaked in both groups 30 minutes after protamine administration. Plasma levels of terminal complement complex were significantly higher at the end of CPB and after protamine administration in group C. Elastase levels were significantly higher 2 and 24 hours after CPB in group C. The ventilation time of patients in group H was significantly lower than that of patients in group C: 10 (range, 3 to 24) versus 22 (range, 7 to 24) hours, respectively (p < 0.01).

Conclusions. The present study confirms the proinflammatory nature of pediatric operations and demonstrates a lessened systemic inflammatory response with the use of heparin-bonded oxygenators. This is achieved without bonding of the entire circuit, which could have significant cost-benefit implications by negating the need for custom-built heparin-bonded circuitry.     

Special Immunization Considerations of the Preterm Infant

More changes to the American Academy of Pediatrics Recommended Immunization Schedule have occurred in the past 3 years than in the previous decade. Selection of the optimal immunization regimen is essential to forestall immunization delay. New complications to the schedule pose challenges for the care of preterm infants who are at increased risk of mortality and morbidity from vaccine-preventable diseases. This article reviews the relevant data regarding immunization of preterm infants and suggests strategies for prevention of immunization delay. Protection of preterm infants, especially for pertussis and influenza, involves not just assessing a child's vaccination status but those of other close contacts and household members.