Dutasteride prevents the growth response to testosterone in benign and androgen-sensitive malignant prostate cells.

We show that the dual 5-α reductase enzyme inhibitor dutasteride prevents enhanced growth of both benign and malignant prostate cell lines, incubated with physiologic to supraphysiologic doses of testosterone. Using androgen-sensitive benign BPH-1 cells, LNCaP cancer cells, their derivative C4-2 cells, or Dunning rat cancer cells, we subjected 30,000 cells/well to concomitant treatment with 10(-9), 10(-8), or 10(-7) M testosterone in the presence of low (0.25 µM) or high (1.0 µM) doses of dutasteride. Both low- and high-dose dutasteride abrogated testosterone-stimulated growth of all 4 cell lines. If the in vitro data mimic conditions in men undergoing testosterone replacement, concomitant dutasteride use might make testosterone safe for men with benign prostatic hypertrophy, latent prostate cancer and perhaps even aggressive prostate cancer. Testosterone might also be used to prevent the rare anti-androgen side effects of dutasteride when used for benign prostatic hypertrophy and baldness. Further clinical investigation is indicated.

Drug interactions and pharmacogenetic reactions are the basis for chloroquine and mefloquine-induced psychosis.

BACKGROUND: Chloroquine and mefloquine used for prophylaxis and treatment of malaria sometimes causes severe mental status changes, through mechanisms that are poorly understood. PRESENTATION OF THE HYPOTHESIS: Psychosis is caused by interactions with other drugs or by pharmacogenetic vulnerabilities that cause heightened responses to chloroquine or mefloquine alone, mediated through dopamine, acetylcholine, serotonin, P-glycoprotein, inhibited cortical activity, deranged calcium homeostasis, and impaired synaptogenesis. TESTING THE HYPOTHESIS: Retrospective studies can identify all other drugs taken coincident with chloroquine or mefloquine psychosis. Various genes from patients could be cloned and compared to those from individuals who tolerated chloroquine and mefloquine, culminating with transgenic animal studies. Identification of candidate genes may be aided by pharmacogenomic analysis of single nucleotide polymorphism maps. Finally, prospective studies with cerebrospinal fluid analysis and PET scanning could help verify the hypothesis. IMPLICATIONS OF THE HYPOTHESIS: If this hypothesis is correct, the incidence of chloroquine and mefloquine psychosis can be greatly reduced by avoiding interacting medications and by conducting genetic screening prior to initiating chloroquine and mefloquine. Validation of the hypothesis would also provide a paradigm to follow for avoiding neuropsychiatric side effects if antidepressants and neuroleptics are used to overcome chloroquine resistance, if new antimalarial drugs chemically related to chloroquine and mefloquine are developed and if chloroquine and mefloquine are used for non-malarial applications such as HIV and cancer.

Gene transfer to brain and spinal cord using recombinant adenoviral vectors.

Recombinant adenoviral (Ad) vectors are derived from human adenoviruses: nonenveloped, encapsidated linear, double-stranded DNA viruses that commonly cause respiratory and gastrointestinal infections. Forty-three different human adenovirus serotypes have been characterized. Details about production of recombinant Ad vectors are given in Chapter 1. Ad vectors in widespread use are derived from human Ad serotypes 2 and 5 (Ad2 and Ad5), Ad5 being more common for applications in the central nervous system (CNS). Ad5 replication-impaired vectors most often contain deletions in the E1 and E3 regions, with transgenes driven by a variety of promoters including viral promoters, and those that are neuron-specific (2). Recently fiber-modified and "gutless" Ad vectors, and those based on canine adenovirus serotype 2, have been developed for use in brain (3-9).

Towards therapy using RNA interference.

Small interfering RNA (siRNA) molecules are short sequences of double-stranded RNA 19-27 bp in length, which suppress expression of target genes by inducing the breakdown of the cognate mRNA through mechanisms that are still being elucidated. siRNA molecules can be chemically synthesized or prepared through digestion of larger double-stranded RNA molecules using recombinant dicer or RNAase III enzyme. siRNA molecules can also be encoded by plasmid or virus vectors or expressed in transgenic animals. Design of siRNA sequences that efficiently suppress target genes can sometimes be challenging, although digestion of large double-stranded RNA species with recombinant dicer or RNAase III may remove the necessity for testing multiple candidate siRNA. Exogenous siRNA can suppress translation for varying amounts of time depending on the half-life of the protein targeted. Vector-mediated approaches may improve duration but their use can be limited by the permanency and efficiency of transduction. Potential therapeutic targets for siRNA include viral and non-viral pathogens, cancer, neurodegenerative diseases, septic shock and macular degeneration. Suppression of expression via siRNA is also an extremely useful research tool for ascertaining gene function. Looking ahead to clinical applications, it will be important to know the consequences of inadvertent suppression of non-targeted sequences. If safety can be established, siRNA has the potential to significantly impact the field of molecular medicine.

Ethacrynic acid can be effective for refractory congestive heart failure and ascites.

Ethacrynic acid is a loop diuretic little used today because of its side-effect profile and the availability of multiple alternative agents. However, in our clinical experience, ethacrynic acid can alleviate acute congestive heart failure and ascites resistant to other diuretics. Two patients aged 89 and 94 in life-threatening pulmonary edema were stabilized by ethacrynic acid after furosemide proved ineffective. A third patient, aged 83, with a pleural effusion and ascites secondary to end-stage hepatitis B and C, responded to ethacrynic acid when spironolactone and furosemide produced little urine output. Ethacrynic acid may have a unique niche as a diuretic of last resort, especially in geriatric practice.

Transduction of neurons lining the cerebral external capsules in mice with feline immunodeficiency virus based vectors.

Gene therapy in the brain has focused mainly on neurons (gray matter), with little comparable research on white matter. In this study, injections into mice cerebral white matter of mice were done to assess the distribution of gene transfer with recombinant feline immunodeficiency virus vectors expressing either beta-galactosidase or beta-glucuronidase. Our results show that vectors were preferentially distributed along the white matter of the external capsule, which was the site of vector injection as confirmed by horseradish peroxidase labeling. Moreover, we found gene transfer almost exclusively to NeuN(+) cells lining the external capsule, which then robustly secreted recombinant beta-glucuronidase throughout the white matter of the entire external capsule on the injected side. These results may have application to lysosomal storage diseases with widespread central nervous system deficits, and other disorders such as multiple sclerosis and human immunodeficiency virus dementia.

Widespread dispersal of cholera toxin subunit b to brain and spinal cord neurons following systemic delivery.

We have discovered novel transport properties of cholera toxin subunit b beyond well-known anterograde and retrograde axonal transport. Injection of 1500 microg of CTb intraperitoneally or intravenously in young adult mice resulted in generalized enhanced labeling of motor nuclei at all levels of the brain stem and spinal cord (oculomotor, trochlear, abducens, facial, trigeminal, vagal, hypoglossal, cervical, and lumbar). There was also extensive labeling of trigeminal and spinal primary afferent fibers, bulk labeling of the area postrema, and finally numerous labeled neurons in the periventricular and supraoptic hypothalamic nuclei. Generalized labeling of motor, sensory, and hypothalamic neurons could also be produced on a more limited scale from intramuscular injections of 500 microg of CTb in the tongue. Neuronal uptake of peripherally administered CTb may be useful as a research tool, or, when fused to therapeutic peptides, enzymes, growth factors, or gene therapy vectors, may have application in amyotrophic lateral sclerosis, diabetic neuropathy, motor neuronopathic lysosomal storage diseases, and other neurodegenerative disorders.