Gail Anderson - US grants

Patients with epilepsy experience a variety of endocrine-related problems, of which the most widely reported is the effect on sexual function. A precise etiology for the effect on sexual function has not been established. Both a direct effect on steroid hormone levels and an indirect CNS effect have been suggested. The specific aims of this proposal are based on the hypothesis that antiepileptic drugs (AEDs) cause endocrine-related effects by interacting with adrenal and gonadal enzymes involved in steroid synthesis and/or hepatic enzymes involved in steroid degradation. Specifically, we evaluated the effects of the AED known as valproic acid. Adrenal glands, liver, testicles and ovaries from Macaca nemestrina were obtained from the tissue program at the Washington RPRC. In the initial studies we determined the optimal culture conditions for adrenal glands, testes and ovaries. Valproic acid had a direct effect on cortisol production in adrenal cells and estradiol production in ovarian and testicular cells, suggesting that the endocrine side effects of valproic acid are caused by direct interaction with the enzymes involved in steroid synthesis and/or degradation.

DESCRIPTION (provided by applicant): Gaining a better understanding of interactions between antibiotics and cranberry juice is of critical importance to a patients with urinary tract infections (UTI). With annual 7 to 8 million office visits for UTIs, addressing this interaction is also of public health concern. Men are less prone to UTIs than women; 20% of women have at least one UTI and a substantial portion have recurrent UTIs. Similarly, children are afflicted with UTIs, albeit at a lower frequency but with the added risk of pyelonephritis and chronic renal dysfunction with undertreatment. The bacterial pathogens in UTI are typically responsive to trimethoprim-sulfamethoxazole, quinolones, and the beta-lactams (penicillins, cephalosporins). The cephalosporin antibiotics are especially useful in the cases of resistance to amoxicillin and trimethoprim-sulfamethoxazole and treatment of chronic or recurrent infections. Cranberry juice is widely used to prevent and treat UTI in spite of limited evidence of efficacy. Recent studies have shown that other fruit juices (i.e., grapefruit, orange and apple juice) can alter the bioavailability of drugs. Grapefruit juice inhibits intestinal CYP 3A, significantly increasing the plasma concentrations of drugs that undergo extensive pre-systemic CYP 3A metabolism. The furanocoumarins and bioflavonoids, which are present in these juices and cranberry juice, inhibit intestinal OATP activity and co-administration of grapefruit, orange or apple juice significantly reduced the oral absorption of the OATP substrate fexofenadine, which is a commonly used antihistamine. These findings represent the first example of food-drug interactions involving altered activity of epithelial (i.e., intestinal) drug transporter function. The intestinal absorption of many beta-lactam antibiotics is mediated by peptide transporters (e.g. PepT1) and possibly OATP. Moreover, the renal clearance of several penicillin and cephalosporins involves proximal tubular secretion, which is governed by organic anion transporters (viz. OATs) and peptide transporters (viz. PepT2) at the basolateral and apical membranes of the tubular epithelium, respectively. Since cranberry juice contained bioflavonoids as in the citrus juices and a high content of organic acids (e.g. benzoic acid), we hypothesize that cranberry juice has the potential to modulate the absorption and renal excretion of many beta-lactam antibiotics. This altered transport could lower the urinary concentrations of select beta-lactam antibiotics and the effectiveness of the antibiotic in treating the UTI. The proposed studies are designed to first, determine whether concurrent cranberry juice administration lowers the urinary concentrations of two commonly used beta-lactam antibiotics, amoxicillin and cefaclor, in children. Secondly, to conduct a rigorous study on amoxicillin pharmacokinetics in adult healthy women that will separate the actions of cranberry juice on intestinal absorption and renal clearance of this prototype beta-lactam antibiotic. The in vivo pharmacokinetic studies will be accompanied by a comprehensive series of experiments in vitro that should reveal the precise effects of cranberry juice and its ingredients and metabolites on the individual transporters of concern.

DESCRIPTION (provided by applicant): Traumatic brain injury (TBI) is a major cause of long-term disability in the United States. Although more individuals survive traumatic brain injury than in the past, the survivors endure residual physical, cognitive, emotional and/or behavioral impairments from the cascade of biochemical responses resulting from TBI. The etiology of secondary brain injury is multi-factorial, with a host of likely interrelated processes: mitochondrial energy failure, excessive generation of reactive oxygen species, activation of destructive enzymes such as poly (ADP-ribose) polymerase (PARP), membrane disruption, neuronal death, thrombosis due to intravascular coagulation in small vessels, increased synaptic concentrations of excitatory amino acids, and activation of innate inflammatory responses. As secondary brain injury is multi-factorial, pharmacological strategies of neuroprotection must include drugs that target multiple mechanisms of the secondary injury. Translation of positive pre-clinical experimental studies into large randomized, controlled trials has been uniformly negative. The reason for the failure of the trials is probably due to many factors also. Specifically relevant to this proposal, the pre-clinical studies often failed to optimize the dose and dosage regimen, doses were often administered at non-clinically relevant times, i.e. pre-injury or immediately after injury with an overall absence of pharmacokinetic data to guide rational dosing. The primary objective of the proposal is to determine the optimal multi-drug therapy to promote neurological recovery in an animal model of traumatic brain injury using behavioral, histological and gene expression markers of neuroprotection to select the drugs and maximize the dosage regiment 1) by identifying combination therapy that targets the maximum number of molecular, cellular and biochemical secondary effects of TBI based on the pharmacologic properties of the drugs and 2) by determining the optimal dosage regimen in animals which would correlate to the proposed treatment of TBI in humans based on pharmacokinetic properties. Optimization includes the time of first dose, the dosage interval and the duration of treatment. PUBLIC HEALTH RELEVANCE: Trauma to the head is a major cause of long-term disability in the United States. People who survive a head injury often have chronic health problems, including physical, emotional and behavioral problems. The cause of the long-term health problems may be due to many different biochemical effects that start occurring immediately after the head injury as the brain attempts to heal itself. There have been many failed studies of single drugs in patients with head injuries suggesting that combinations of drugs may be more effective. This study will help to identify combinations of drugs that could be used to prevent the long-term effects.