Ocular pharmacokinetics of cephalosporins using microdialysis.

The purpose of this study was to delineate the ocular pharmacokinetics of cephalosporins and investigate the presence of peptide transporters in the retina. New Zealand albino rabbits were kept under anesthesia. A concentric microdialysis probe was implanted in the vitreous chamber and linear probe across the cornea in the aqueous humor. Isotonic phosphate buffer saline was perfused through the probes, and samples were collected every 20 min over a period of 10 hr. A 500 microg dose of cephalexin, cephazolin, and cephalothin was administered intravitreally. Inhibition experiments were carried out in vivo, using gly-pro and gly-sar. The vitreal half-lives of cephalexin, cefazolin, and cephalothin were 185.38 +/- 27.25 min, 111.40 +/- 17.17 min, and 146.68 +/- 47.52 min, respectively. Cephalexin generated higher aqueous humor concentrations compared to cefazolin. The pharmacokinetic parameters of cephalexin in the presence of gly-pro, i.e., AUC (44452.06 +/- 3326.55 microg x min/ml), clearance (0.0013 +/- 0.0004 ml/min) and vitreal half-life (825.12 +/- 499.95 min) were different from that of the control (14612.83 +/- 4036.47 microg x min/ml, 0.0036 +/- 0.0011 ml/min, and 187.96 +/- 65.12 min, respectively). Gly-pro did not inhibit cefazolin, and gly-sar showed no effect on the pharmacokinetics of both drugs. These studies indicate the involvement of a peptide carrier in the transport of cephalosporins across the retina. Although gly-pro inhibited the elimination of cephalexin from the vitreous, the effect of an alpha-amino group on peptide carriers was not clearly evident.     

Changes in microRNA (miRNA) expression during pancreatic cancer development and progression in a genetically engineered KrasG12D;Pdx1-Cre mouse (KC) model

Differential expression of microRNAs (miRNAs) has been demonstrated in various cancers, including pancreatic cancer (PC). Due to the lack of tissue samples from early-stages of PC, the stage-specific alteration of miRNAs during PC initiation and progression is largely unknown. In this study, we investigated the global miRNA expression profile and their processing machinery during PC progression using the Kras^G12D;Pdx1-Cre (KC) mouse model. At 25 weeks, the miRNA microarray analysis revealed significant downregulation of miR-150, miR-494, miR-138, miR-148a, miR-216a, and miR-217 and upregulation of miR-146b, miR-205, miR-31, miR-192, and miR-21 in KC mice compared to controls. Further, expression of miRNA biosynthetic machinery including Dicer, Exportin-5, TRKRA, and TARBP2 were downregulated, while DGCR8 and Ago2 were upregulated in KC mice. In addition, from 10 to 50 weeks of age, stage-specific expression profiling of miRNA in KC mice revealed downregulation of miR-216, miR-217, miR-100, miR-345, miR-141, miR-483-3p, miR-26b, miR-150, miR-195, Let-7b and Let-96 and upregulation of miR-21, miR-205, miR-146b, miR-34c, miR-1273, miR-223 and miR-195 compared to control mice. Interestingly, the differential expression of miRNA in mice also corroborated with the miRNA expression in human PC cell lines and tissue samples; ectopic expression of Let-7b in CD18/HPAF and Capan1 cells resulted in downregulation of KRAS and MSST1 expression. Overall, the present study aids an understanding of miRNA expression patterns during PC pathogenesis and helps to facilitate the identification of promising and novel early diagnostic/prognostic markers and therapeutic targets.     

Defining erythrocyte internal labeling by phosphorylation.

When erythrocytes are incubated with 32Pi, incorporation of label into phosphoproteins is a gradual process, increasing for at least 2 hours. Membrane phospholipids also are labeled. Exogenous protein kinase substrates are unlabeled in these incubations. This suggests that labeling by 32Pi occurs into polypeptides inside the erythrocytes. When erythrocytes are incubated with [gamma-32P]ATP and active protein kinase, membrane polypeptides are not labeled. Only exogenously added protein kinase substrates and the regulatory subunit of protein kinase (and its contaminants) are labeled. This suggests that labeling from [gamma-32P]ATP and active protein kinase occurs in the compartment outside the erythrocytes. Apyrase (EC 3.6.1.5) eliminates such labeling, demonstrating that it was occurring in the compartment external to the erythrocytes. However, in incubations of cells with 32Pi, apyrase has no effect on the incorporation into membrane polypeptides and phospholipids, demonstrating that this labeling occurs on the inside of the membrane. Thus, additions of apyrase to intact particles incubated with protein kinase substrates and 32Pi provides a method for identifying internally exposed polypeptides in the plasma membranes of a variety of systems.     

Pre-transplant obesity in heart transplantation: Are there predictors of worse outcomes?

Objective. Morbid obesity is increasingly observed in patients being evaluated for heart transplantation and represents a relative contraindication. We sought to evaluate the influence of pre-transplant obesity on morbidity and mortality after heart transplantation. Design. We retrospectively reviewed 90 consecutive patients with preoperative obesity (BMI ≥ 30) and 90 age matched patients with normal weight (BMI 19 – 26) who underwent heart transplantation at our institution between January 1997 and December 2005. Results. Morbidly obese patients experienced higher rates of pre-transplant diabetes (29% vs 15%, p < 0.05) and prolonged waiting time before transplantation (191.4±136.1 vs 117.4±143.2 days, p < 0.001). There were no significant differences in post-operative complications including rejection and major and minor infections. There was no difference in actuarial survival between the obese and control groups after a mean follow-up of 4.26±2.95 years (p = 0.513, log-rank statistic 0.452). Causes of death did not differ. Cox proportional hazard analysis revealed increased association of peripheral vascular disease (HR 31.718, p = 0.001), and pre operative inotropic support (HR 33.725, p = 0.013) with increased mortality in the obese group. Conclusions. This study suggests morbid obesity does not affect survival or rates of infection and rejection after heart transplantation.     

Coronary surgery in elderly patients. In-hospital and long-term results]

BACKGROUND: Taking into account the steady increase in the number of elderly patients requiring coronary artery bypass grafting, we sought to analyze the in-hospital and long-term evolution of a group of elderly patients (>/= 75 years) who underwent coronary artery bypass grafting, and to identify clinical predictors of mortality and long-term symptoms. METHODS: Between April 1996 and February 2000, 207 patients older than 75 years of age who had undergone coronary bypass grafting were prospectively and consecutively analyze. Mean age was 78.4 +/- 2.7. RESULTS: An average of 2.6 grafts/patients was constructed. Left mammary artery was used in 93% of patients. The in-hospital incidence of heart failure, atrial fibrillation, preoperative infarction and stroke was 38%, 29%, 4.8% and 2.8% respectively. The in-hospital mortality rate was 5.8%. Mean follow-up was 18 months (25th an 75th percentiles 9-29). Late mortality rate was 4.1% in eight patients. Excluding the in-hospital deaths, the estimated probability of survival (Kaplan-Meier) at 3 years was 94% and the survival freedom from symptoms was 86%. A multivariate analysis showed that only age was predictor of in-hospital mortality (OR 1.16, p = 0.009). Only peripheral vascular disease was found as a predictor of symptoms during the long-term follow-up (p = 0.001). CONCLUSIONS: In this series of senile patients who underwent coronary surgery, those of an older age (> 80 years) showed a higher risk of in-hospital mortality. The presence of peripheral vascular disease is useful in the prognosis assessment of the group.     

Promoter hypermethylation in Indian primary oral squamous cell carcinoma

We evaluated promoter hypermethylation of a panel of tumor suppressor genes as a means to detect epigenetic alterations in oral squamous cell carcinomas (OSCC) of Indian‐origin and compare with North‐American head and neck squamous cell carcinomas (HNSCC). Quantitative‐methylation‐specific PCR was used to investigate the promoter methylation status of DCC, EDNRB, p16^INK4a and KIF1A in 92 OSCC, and compared to 48 paired normal tissues and 30 saliva and sera samples from healthy control subjects. Aberrant methylation of at‐least one of these genes was detected in 74/92 (80.4%) OSCC; 72.8% at EDNRB, 71.7% at KIF1A, 47.8% at p16^INK4a and 58.7% at DCC; and in 5 of 48 (10.4%) normal oral tissues. None of the saliva and sera samples from controls exhibited DNA methylation in these four target genes. Thirty‐two of 72 node positive cases harbored p16^INK4a and DCC hypermethylation (p = 0.005). Thus, promoter hypermethylation in genes analyzed herein is a common event in Indian OSCC and may represent promising markers for the molecular staging of OSCC patients. We found higher frequency of p16^INK4a methylation (47.8%) in this Indian cohort in comparison with a North‐American cohort (37.5%). In conclusion, aberrant methylation of EDNRB, KIF1A, DCC and p16^INK4a genes is a common event in Indian OSCC, suggesting that epigenetic alterations of these genes warrant validation in larger studies for their potential use as biomarkers.