Neutral and DEAE dextrans as tracers for assessing lung microvascular barrier permeability and integrity

A generic whole body physiologically based pharmacokinetic model for therapeutic proteins in PK-Sim

Proteins are an increasingly important class of drugs used as therapeutic as well as diagnostic agents. A generic physiologically based pharmacokinetic (PBPK) model was developed in order to represent at whole body level the fundamental mechanisms driving the distribution and clearance of large molecules like therapeutic proteins. The model was built as an extension of the PK-Sim model for small molecules incorporating (i) the two-pore formalism for drug extravasation from blood plasma to interstitial space, (ii) lymph flow, (iii) endosomal clearance and (iv) protection from endosomal clearance by neonatal Fc receptor (FcRn) mediated recycling as especially relevant for antibodies. For model development and evaluation, PK data was used for compounds with a wide range of solute radii. The model supports the integration of knowledge gained during all development phases of therapeutic proteins, enables translation from pre-clinical species to human and allows predictions of tissue concentration profiles which are of relevance for the analysis of on-target pharmacodynamic effects as well as off-target toxicity. The current implementation of the model replaces the generic protein PBPK model available in PK-Sim since version 4.2 and becomes part of the Open Systems Pharmacology Suite.

Chemotherapy-induced changes in cardiac capillary permeability measured by fluorescent multiple indicator dilution

Anthracyclines cause severe irreversible cardiac toxicity. The study of changes in cardiac permeability with chemotherapy could enhance the understanding of mechanisms behind cardiac damage, and provide useful information to evaluate anthracycline cardiotoxicity. Thirty-six rats (12 Sprague-Dawley, 12 Wistar, 12 Fischer-344) were randomly assigned to control (n = 21) or doxorubicin (n = 15), and injected i.p. with a cumulative dose of 18 mg/kg doxorubicin in saline (vehicle) or vehicle alone over 12 days. Echocardiography was performed at baseline and on day 11. An isolated heart experiment was done on day 12 to obtain perfused heart pressure values, and to measure cardiac capillary permeability using a Texas Red/sodium fluorescein multiple indicator dilution method. Control animals had significantly lower average permeability-surface-area-products (0.035 ± 0.013 cm(3)/s) than doxorubicin animals (0.066 ± 0.023 cm(3)/s), PSP ± SD, p < 0.001. These permeability changes correlated with significant functional changes. There was a significant decline in cardiac function with a deleterious effect of chemotherapy on fractional shortening (p < 0.001), left ventricular developed pressure (p < 0.001), contractility (p < 0.001), and relaxation (p = 0.02). Based on our results, cardiac capillary permeability changes can be detected after in vivo chemotherapy treatment using our fluorescent multiple indicator dilution technique, and may provide valuable information in evaluating cardiotoxicity of novel drugs.

Factors associated with risky sexual practices among female sex workers in Karnataka, India

Introduction

The objectives of this study are to develop a summary measure of risky sexual practice and examine the factors associated with this among female sex workers (FSWs) in Karnataka, India.

Materials and Methods

Data were drawn from special behavioral surveys (SBS) conducted in 2007 among 577 FSWs in two districts of Karnataka, India: Belgaum and Bangalore. FSWs were recruited using the two-stage probability sampling design. FSWs' sexual practice was considered risky if they reported inconsistent condom use with any sexual partner and reported experience of one of the following vulnerabilities to HIV risk: anal sex, alcohol consumption prior to sex and concurrent sexual relationships.

Results

About 51% of FSWs had engaged in risky sexual practice. The odds of engaging in risky sex were higher among FSWs who were older (35+ years) than younger (18–25 years) (58% vs. 45%, Adjusted Odds Ratio (AOR): 2.0, 95% confidence interval (CI): 1.2–3.4), who were currently married than never married (61% vs. 51%, AOR: 4.8, 95% CI: 2.5–9.3), who were in sex work for 10+ years than those who were in sex work for less than five years (66% vs. 39%, AOR: 2.6, 95% CI: 1.6–4.2), and who had sex with 3+ clients/day than those who had sex with fewer clients (67% vs. 38%, AOR: 3.7, 95% CI:2.5–5.5).

Conclusion

FSWs who are older, currently married, practicing sex work for longer duration and with higher clientele were more likely to engage in risky sexual practices. HIV prevention programs should develop strategies to reach these most-at risk group of FSWs to optimize the effectiveness of such programs.

Pleural fluid exchange in rabbits

BACKGROUND AND OBJECTIVES

The study was designed to better characterize pleural fluid absorption in rabbits with the following two objectives: to determine the relative absorption of saline versus high-protein solutions, and to identify the relative rates of absorption of dextran molecules of varying sizes.

METHODS

Twenty New Zealand white rabbits received a 12-mL intrapleural injection of saline solution and a 10% protein solution on opposite sides, each solution containing dextran molecules with varying MWs. At sacrifice at 1, 4, 8, 18 and 24 h, the volume of pleural fluid and the concentrations of the dextran molecules were determined.

RESULTS

Saline was absorbed faster than the high-protein fluid (P < 0.001). Dextran concentrations in the saline were significantly higher than those in the protein solution at all times after injection (P = 0.005; P < 0.001, respectively). The higher-MW dextrans were cleared more slowly than the lower-MW dextrans in a continuously graded manner.

CONCLUSIONS

Saline was absorbed faster than a solution with a high protein content. There was a continuous spectrum in the rate of absorption of the dextran molecules, with the larger molecules being absorbed more slowly.