Molecular adsorbent recirculating system: albumin dialysis-based extracorporeal liver assist device

Extracorporeal liver assist devices have been used for more than five decades to support patients with liver failure. Numerous modifications have been made to both biological as well as mechanical liver assist devices. Possibly, an ideal liver assist device would be one that would perform optimal detoxification and synthetic functions of the liver, be simple to set up and yet be cost-effective. An albumin dialysis-based device that uses a hybrid albumin-impregnated membrane to get rid of albumin-bound toxins that circulate in abundance in liver failure, called the molecular adsorbent recirculating system (MARS) has been in clinical use for nearly four years now. Results with the use of this device in both acute and acute-on-chronic liver failure have shown consistent improvement in biochemical profile, resolution of encephalopathy, correction in hemodynamics, reduction in intracranial pressure and some improvement in the synthetic function of the liver. In a number of studies, albeit of small sample size, survival advantage has also been observed. The timing of initiation of therapy with MARS, duration of treatment, frequency of sessions and 'maintenance therapy' are still some of the unresolved issues with the use of this device. Large multicentric trials on the use of this technique are expected to throw light on these issues and help optimize the potential of this liver assist device.     

Chemical Asphyxiants and Noise

The damaging effects of noise on auditory function can be altered significantly by exposure to additional agents that may or may not by themselves be ototoxic. This chapter focuses on the ability of chemical asphyxiants present in both occupational settings and ambient environments to potentiate noise induced hearing loss in a laboratory animal model. Since the chemical agents under study do not produce permanent impairment of hearing by themselves, the finding of auditory impairment in excess of that which is produced by noise exposure alone can be defined as noise potentiation. This chapter focuses both on the exposure conditions that favour such potentiation and also on potential mechanisms for potentiation. The data show that low to moderate exposure levels of carbon monoxide (CO) and hydrogen cyanide can potentiate noise induced hearing loss (NIHL) and the relationship between such levels and those permitted in work environments is provided. Finally, evidence is presented that free oxygen radicals may be responsible for potentiation of NIHL by the chemical asphyxiants. First, the ability of a free radical spin trap agent, PBN, to prevent the adverse effects of CO is demonstrated. Then, in an additional experiment, electron paramagnetic spin resonance is used to demonstrate a high level of free radicals in the cochlea with combined exposure to CO + noise while individual exposures to CO and noise do not produce free radicals at levels detectable by this method.     

Aerosolization of lipoplexes using AERx Pulmonary Delivery System

The lung represents an attractive target for delivering gene therapy to achieve local and potentially systemic delivery of gene products. The objective of this study was to evaluate the feasibility of the AERx Pulmonary Delivery System for delivering nonviral gene therapy formulations to the lung. We found that "naked" DNA undergoes degradation following aerosolization through the AERx nozzle system. However, DNA formulated with a molar excess of cationic lipids (lipoplexes) showed no loss of integrity. In addition, the lipoplexes showed no significant change in particle size, zeta (zeta) potential, or degree of complexation following extrusion. The data suggest that complexation with cationic lipids had a protective effect on the formulation following extrusion. In addition, there was no significant change in the potency of the formulation as determined by a transfection study in A-549 cells in culture. We also found that DNA formulations prepared in lactose were aerosolized poorly. Significant improvements in aerosolization efficiency were seen when electrolytes such as NaCl were added to the formulation. In conclusion, the data suggest that delivery of lipoplexes using the AERx Pulmonary Delivery System may be a viable approach for pulmonary gene therapy.     

Herpes zoster infection: a rare cause of acute urinary retention

Herpes zoster (HZ) infection has been reported as a rare cause of acute urinary retention. HZ infection involving sacral, thoracolumbar, and rarely high thoracic dermatomes is believed to occasionally cause motor and sensory neuropathy of the bladder. This is specifically achieved by the interruption of the detrusor reflex causing subsequent bladder atonia. As the course and management of this entity is quite benign, HZ should remain a diagnostic consideration in the management of urinary retention. We report a case of acute urinary retention of approximately 2.5 liters associated with HZ infection and review the proposed pathogenesis and therapeutic considerations in the management of this entity.     

Ethical issues in public health policy

Ethics in public health policy is given the least importance and rarely discussed. Resolving ethical issues in public health is often an arduous task as these are complicated and require careful handling. Using four case studies, we discuss issues pertaining to pertussis and brain damage, water fluoridation and dental caries, infection with the human immunodeficiency virus and the right to marriage, and the debate surrounding universal salt iodization. The core issue in all these examples pertains to the relevance of ethics in public health policy.