MK-801- and ethanol-induced activity in inbred long-sleep and short-sleep mice: dopamine and serotonin systems

Low doses of (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine (MK-801; dizocilpine) or ethanol induce less locomotor activation in inbred long-sleep (ILS) than short-sleep (ISS) mice. These differences may involve altered dopamine and/or 5-hydroxytryptamine (serotonin; 5-HT) neurotransmission. To address this possibility, the dopaminergic and serotonergic mechanisms underlying the locomotor-stimulant effects of MK-801 and ethanol in ILS and ISS mice were studied. Dopamine D1, D2 and 5-HT(2A) receptor antagonists reduced MK-801-stimulated activity in ILS mice without having any effect in ISS mice. The 5-HT reuptake inhibitor fluoxetine potentiated MK-801-stimulated activity selectively in ILS mice. Strain differences in 5-HT transporters do not explain this selective effect of fluoxetine in ILS mice since [3H]citalopram binding and [3H]5-HT uptake studies found no differences in the affinity, number or function of 5-HT transporters between ILS and ISS mice. Ethanol-induced activity in ISS mice was depressed by dopamine D2 and 5-HT(2C) receptor antagonists and enhanced by a 5-HT(1A) receptor antagonist. These results suggest that in ILS mice the locomotor-stimulant effects of MK-801 require increased dopamine and/or 5-HT neurotransmission. Conversely, in ISS mice, the effects of MK-801 appear to be monoamine-independent. Thus, even though both MK-801 and ethanol inhibit N-methyl-D-aspartate receptors, their stimulant effects appear to involve different neuronal systems.     

Synthesis of ketone analogues of prolyl and pipecolyl ester FKBP12 ligands

The recently discovered small-molecule ligands for the peptidyl and prolyl isomerases (PPIase) of FKBP12 have been shown to possess powerful neuroprotective and neuroregenerative effects. Ketone analogues of the prolyl and pipecolyl esters, which mimic only the FKBP binding domain portion of FK506, are proposed and an efficient synthetic strategy is presented in this report, along with the preliminary results of in vitro and in vivo biological studies.     

Safety assessment for hair-spray resins: risk assessment based on rodent inhalation studies

The methods involved in the safety assessment of resins used in hair-spray products have received little peer review, or debate in the published literature, despite their widespread use, in both hairdressing salons and the home. The safety assessment for these resins currently involves determining the type of lung pathology that can be caused in animal inhalation exposure studies, and establishing the no-observable-effect level (NOEL) for these pathologies. The likely human consumer exposure is determined by techniques that model the simulated exposure under "in use" conditions. From these values it is then possible to derive the likely safety factors for human exposure. An important part of this process would be to recognize the intrinsic differences between rodents and humans in terms of the respiratory doses that each species experiences during inhalation exposures, for the purpose of the safety assessment. Interspecies scaling factors become necessary when comparing the exposure doses experienced by rats, compared to humans, because of basic differences between species in lung clearance rates and the alveolar area in the lungs. The rodent inhalation data and modeled human exposure to Resin 6965, a resin polymer that is based on vinyl acetate, has been used to calculate the safety factor for human consumer exposure to this resin, under a range of "in use" exposure conditions. The use of this safety assessment process clearly demonstrates that Resin 6965 is acceptable for human consumer exposure under the conditions considered in this risk assessment.     

Role of cytochrome P450 1a1 and 1b1 in the metabolic activation of 7,12-dimethylbenz[a]anthracene and the effects of naturally occurring furanocoumarins on skin tumor initiation

The current study was designed to determine the mechanistic basis for differences in the effects of naturally occurring furanocoumarins on skin tumor initiation by 7,12-dimethylbenz[a]anthracene (DMBA). Female SENCAR mice were pretreated topically with bergamottin, imperatorin, or isopimpinellin (100-3200 nmol), 7,8-benzoflavone (7,8-BF, 5-40 nmol, a known inhibitor of DMBA skin carcinogenesis in mice), or acetone (vehicle control) 5 min prior to topical treatment with DMBA (10 nmol). Imperatorin, isopimpinellin, and 7,8-BF, but not bergamottin, significantly blocked total DMBA-DNA adduct formation. HPLC analysis of DNA adducts revealed that bergamottin preferentially inhibited formation of anti-DMBA diol-epoxide (DMBADE) derived DNA adducts, imperatorin, and isopimpinellin inhibited both anti- and syn- derived adducts, whereas 7,8-BF showed some selectivity for reduction of syn-DMBADE-DNA adducts. Mouse embryo fibroblast C3H/10T1/2 (10T1/2) cells, and mouse hepatoma-derived 1c1c7 (Hepa-1) cells, which preferentially express P450 1b1 and P450 1a1, respectively, were co-incubated with 2 microM bergamottin, imperatorin, isopimpinellin, and 7,8-BF, and with DMBA (2 microM). Hepa-1 cells (P450 1a1) formed mainly anti-DMBADE-DNA adducts. In contrast, 10T1/2 cells (P450 1b1) formed mainly syn-DMBADE-DNA adducts. Bergamottin inhibited DMBA metabolism to DMBA-3,4-diol and blocked DNA adduct formation in Hepa-1 cells, but had little effect in 10T1/2 cells. In contrast, 7,8-BF completely blocked DMBA metabolism and DNA adduct formation in 10T1/2 cells, but had little effect in Hepa-1 cells. Imperatorin and isopimpinellin inhibited DMBA bioactivation in both cell lines. These results indicate that bergamottin is a more selective inhibitor of P450 1a1 and overall a less effective inhibitor of the metabolic activation of DMBA in mouse epidermis. In contrast, imperatorin, isopimpinellin, and especially 7,8-BF, which block metabolic activation of DMBA in mouse epidermis, appear more selective for P450 1b1. On the basis of our studies using 10T1/2 cells and Hepa-1 cells, it appears that P450 1a1 is primarily responsible for converting DMBA-3,4-diol to anti-DMBADE, whereas P450 1b1 is primarily responsible for converting DMBA-3,4-diol to syn-DMBADE. These data demonstrate the role of P450 1a1 and 1b1 in the metabolic activation of DMBA in mouse epidermis and provide a mechanistic explanation for the differential effects of naturally occurring furanocoumarins (and 7,8-BF) on polycyclic aromatic hydrocarbon skin carcinogenesis.     

Clinical implications of CNS penetration of antiretroviral drugs

The CNS serves as an important sanctuary site for HIV replication. The presence of HIV in this compartment may contribute to neurological complications in individuals infected with HIV. Understanding the CNS penetration capabilities of available antiretroviral agents may help clinicians to design treatment regimens with neuroprotective effects. Although numerous clinical studies and anecdotal reports have examined CSF antiretroviral drug exposure as a marker of CNS penetration, understanding the clinical relevance of these findings is difficult. Challenges with study design and subject recruitment often limit the investigator's ability to collect comprehensive data. Upon review of available data, the antiretroviral agents zidovudine, stavudine, lamivudine, nevirapine, efavirenz and indinavir demonstrate consistent penetration into the CSF. Zidovudine-, stavudine-, lamivudine-, didanosine- and protease inhibitor-based regimens also appear to suppress CSF viraemia or improve HIV neurological disease. These agents may be appropriate candidates for neuroprotective antiretroviral treatment regimens. Despite these data, several unanswered questions about the CSF antiretroviral drug exposure-response relationship still remain. Prospective, controlled studies examining this relationship are needed before absolute clinical recommendations are founded.     

Shark cartilage monograph: a clinical decision support tool

The use, adverse effects, mechanism of action, pharmacology, interactions and supporting evidence of shark cartilage is presented. Dosage, toxicology and safety parameters are also discussed.     

Kava monograph: a clinical decision support tool

The proposed uses, dosing parameters, adverse effects, toxicology, interactions and mechanism of action of kava is systematically reviewed in monograph format.     

Dysfunction and infection of freshly isolated blood myeloid and plasmacytoid dendritic cells in patients infected with HIV-1

Recently it has been shown that the 2 populations of blood dendritic cells (DCs), termed plasmacytoid (pcDCs) and myeloid (myDCs), are reduced in HIV-1 infection. This study aimed to determine whether these 2 populations are targets for HIV-1 infection and whether their ability to stimulate T-lymphocyte proliferation is affected. Highly purified populations of myDCs and pcDCs were isolated from the blood of antiretroviral treatment-naive patients and assessed for the level of HIV provirus by polymerase chain reaction (PCR). We show that both populations are targets for HIV-1 infection as indicated by the presence of provirus in 12 of 14 pcDC and 13 of 14 myDC samples tested. A proportion of this provirus is integrated in myDCs. The ability of both myDCs and pcDCs from HIV-1-infected patients to stimulate allogeneic T-lymphocyte proliferation in a 6-day mixed leukocyte reaction was severely impaired, but was not mediated by secondary infection of T lymphocytes. Thus, in addition to depletion, both myeloid and plasmacytoid DCs are infected and show impaired functional capacity. These findings suggest that infection, depletion, and dysfunction of dendritic cells may contribute to the immunosuppression associated with HIV-1 disease.