Manufacturing Techniques of Biodegradable Implants Intended for Intraocular Application

Polylactic acid and polylactic-co-glycolic acid are biocompatible and biodegradable polymers with wide utility for the design of controlled release systems for drugs. Regarding intraocular application, polymeric sustained-drug release systems are being studied to treat vitreoretinal diseases. Our work aimed to compare the influence of two implant manufacturing techniques, compression and hot molding, on the in vitro degradation of the polymeric matrices and on the release of dexamethasone acetate. The results showed that the manufacturing technique highly influences degradation and drug release processes. The compressed systems degraded faster and allowed one faster release of the drug.     

Optimization of Cav1.2 screening with an automated planar patch clamp platform

Introduction: Ca_v1.2 channels play an important role in shaping the cardiac action potential. Screening pharmaceutical compounds for Ca_v1.2 block is very important in developing drugs without cardiac liability. Ca_v1.2 screening has been traditionally done using fluorescence assays, but these assays have some limitations. Patch clamping is considered the gold standard for ion channel studies, but is very labor intensive. The purpose of this study was to develop a robust medium throughput Ca_v1.2 screening assay in PatchXpress^® 7000A by optimizing cell isolation conditions, recording solutions and experimental parameters. Under the conditions established, structurally different standard Ca_v1.2 antagonists and an agonist were tested. Methods: HEK-293 cells stably transfected with hCa_v1.2 L-type Ca channel were used. For experiments, cells were isolated using 0.05% Trypsin. Currents were recorded in the presence of 30 mM extracellular Ba²⁺ and low magnesium intracellular recording solution to minimize rundown. Ca_v1.2 currents were elicited from a holding potential of ? 60 mV at 0.05 Hz to increase pharmacological sensitivity and minimize rundown. Test compounds were applied at increasing concentrations for 5 min followed by a brief washout. Results: Averaged peak Ca_v1.2 current amplitudes were increased from 10 pA/pF to 15 pA/pF by shortening cell incubation and trypsin exposure time from 2.5 min at 37 °C to 1 min at room temperature and adding 0.2 mM cAMP to the intracellular solution. Rundown was minimized from 2%/min to 0.5%/min by reducing the intracellular free Mg²⁺ from 2.7 mM to 0.2 mM and adding 100 nM Ca²⁺. Under the established conditions, we tested 8 structurally different antagonists and an agonist. The IC₅₀ values obtained ranked well against published values and results obtained using traditional clamp experiments performed in parallel using the expressed cell line and native myocytes. Discussion: This assay can be used as a reliable pharmacological screening tool for Ca_v1.2 block to assess compounds for cardiac liability during lead optimization.     

Time-dependent changes in cardiac growth after kidney transplantation: the impact of pre-dialysis ventricular mass.

BACKGROUND: Left ventricular hypertrophy (LVH) is common in chronic kidney disease (CKD), including kidney transplant recipients. However, time-related left ventricular mass changes (DeltaLVM) from pre-dialysis stage to beyond the first post-transplant year have not been clearly identified. METHODS: We studied a cohort of 60 stages 4-5 CKD patients without overt cardiac disease, who underwent three echocardiograms during follow-up: at pre-dialysis stage, on dialysis and after kidney transplantation (KT). Multiple linear regression was used to model DeltaLVM from baseline study. Cox proportional analysis was used to determine risk factors associated with either de novo LVH or>20% DeltaLVMI over time. RESULTS: Patients with baseline LVH (n=37; 61%) had a higher body mass index (BMI) than those without LVH (n=23; 39%) (P=0.013). BMI, haemoglobin levels (P=0.047) and non-use of angiotensin-converting enzyme inhibitors (ACEI) (P=0.057) were associated with baseline left ventricular mass index (LVMI). Twelve out of 23 patients (52%) with normal LVM at baseline, developed either de novo LVH or>20% DeltaLVMI at follow-up. On the other hand, 29 (78%) of those with initial LVH maintained this abnormality, and 8 (22%) normalized LVM post-transplantation. Factors associated with DeltaLVMI were age (P=0.01), pre-dialysis LVMI (P<0.0001), serum creatinine (P=0.012) and the use of ACEI post-transplantation (P=0.009). In Cox analysis, pre-dialysis LVMI was associated with de novo LVH or>20% DeltaLVMI over time (hazard ratio 1.009; 95% confidence interval 1.004 to 1.015; P=0.001). CONCLUSIONS: Successful KT may not completely normalize LVM post-transplantation. Pre-dialysis LVMI, traditional risk factors and no use of ACEI may perpetuate cardiac growth following KT.     

Alcohol and Smoking as Risk Factors in Chronic Pancreatitis and Pancreatic Cancer

The aim of this study was to compare alcohol andsmoking as risk factors in the development of chronicpancreatitis and pancreatic cancer. We considered onlymale subjects: (1) 630 patients with chronic pancreatitis who developed 12 pancreatic and 47extrapancreatic cancers; (2) 69 patients withhistologically well documented pancreatic cancer and noclinical history of chronic pancreatitis; and (3) 700 random controls taken from the Verona pollinglist and submitted to a complete medical check-up.Chronic pancreatitis subjects drink more than controlsubjects and more than subjects with pancreatic cancer without chronic pancreatitis (P < 0.001).The percentage of smokers in the group with chronicpancreatitis is significantly higher than that in thecontrol group [odds ratio (OR) 17.3; 95% CI 12.6-23.8; P < 0.001] and in the group with pancreaticcarcinomas but with no history of chronic pancreatitis(OR 5.3; 95% CI 3.0-9.4; P < 0.001). In conclusion,our study shows that: (1) the risk of chronic pancreatitis correlates both with alcoholintake and with cigarette smoking with a trendindicating that the risk increases with increasedalcohol intake and cigarette consumption; (2) alcoholand smoking are statistically independent risk factors forchronic pancreatitis; and (3) the risk of pancreaticcancer correlates positively with cigarette smoking butnot with drinking.     

Increased plasma atrial natriuretic factor in catecholamine-producing tumor patients.

The aim of this study was to evaluate plasma levels of ANF in patients with catecholamine-secreting tumors with and without hypertension and to relate ANF secretion to levels of plasma and urinary catecholamines and blood pressure. Twenty-one pheochromocytoma (15 with sustained, 6 with paroxysmal hypertension), 6 neuroblastoma (1 hypertensive) patients and 28 aged-matched controls were studied in basal conditions. Plasma and urinary norepinephrine (NE),epinephrine (E), dopamine (DA) and DOPA were determined by HPLC-ED and plasma ANF by RIA. Both neuroblastoma and pheochromocytoma patients had significantly higher plasma ANF levels than controls. Neuroblastomas showed higher ANF concentration than pheochromocytomas. No differences were found in plasma ANF between hypertensive and normotensive patients. Pheochromocytomas with ANF levels within the normal range had plasma and urinary NE and urinary DA and DOPA levels significantly higher than patients with high ANF. Plasma ANF levels were unrelated to systolic or diastolic blood pressure or heart rate. A negative correlation between plasma ANF and urinary DA was found only in the patients groups. In conclusion, plasma ANF was increased in pheochromocytoma and neuroblastoma patients. Our data suggest that the excessive catecholamine secretion is not responsible for the increased ANF secretion in these patients. The significance of the relationships among plasma ANF and urinary and plasma catecholamines requires further investigation.     

Lymphoscintigraphy and Lymphatic Mapping for Identification of Sentinel Lymph Nodes

The recently introduced technique of sentinel lymph node dissection (SLND) may replace complete axillary lymph node dissection for axillary staging of early breast cancer. Successful SLND is predicated on meticulous delineation of the lymphatic pathway and sentinel node(s). Currently employed lymphatic mapping materials include vital blue dyes and radioactive tracers. Techniques of intraoperative lymphatic mapping and SLND using dye, tracer, or both have high success rates in the hands of experienced investigators, but their routine and widespread use awaits resolution of questions about the timing, dose, and type of radioactive tracer; the optimal lymphatic mapping technique; indications and contraindications for SLND; and certification of qualified surgeons, pathologists, and nuclear medicine physicians.     

Impact of cold ischemia time on renal allograft outcome using kidneys from young donors

Prolonged cold ischemia time (CIT) is associated with delayed graft function and worse kidney transplant (KT) outcome, but the effect of CIT on long‐term allograft survival in KT from younger donors has not been well established. We investigated the predictive value of CIT exposure on long‐term death‐censored graft loss in 829 KT recipients from younger donors (<50 years) that were performed in our center between 1991 and 2005. Overall death‐censored graft failure rate was significantly higher in CIT≥19 h group versus CIT<19 h group (26 vs. 16.5%; P = 0.002). Significant differences were also observed when patients with primary nonfunctioning graft were excluded (21 vs. 14%; P = 0.020) and in patients who received tacrolimus plus mycophenolate mofetil (12 vs. 4%; P = 0.05). By multivariate Cox analysis, CIT was found to be independently associated with death‐censored graft loss with a 20% increase for every 5 h of CIT [relative risk (RR) 1.04; 95% Confidence Interval (CI): 1.01–1.1; P = 0.021]. Likewise, graft loss risk significantly increased in CIT≥19 h group versus CIT<19 h group (RR 1.5; 95%CI: 1.1–2.1; P = 0.023). Prolonged CIT is an independent predictor of graft survival in KT from younger donors. Efforts at minimizing CIT (<19 h) should improve transplant outcome significantly in this population.