Viral infection causes stress to the endoplasmic reticulum. The response to endoplasmic reticulum stress, known as the unfolded protein response (UPR), is designed to eliminate misfolded proteins and allow the cell to recover by attenuating translation and upregulating the expression of chaperones, degradation factors, and factors that regulate the cell's metabolic and redox environment. Some consequences of the UPR (e.g., expression of chaperones and regulation of the metabolism and redox environment) may be advantageous to the viral infection; however, translational attenuation would not. Thus, viruses may induce mechanisms which modulate the UPR, maintaining beneficial aspects and suppressing deleterious aspects. We demonstrate that human cytomegalovirus (HCMV) infection induces the UPR but specifically regulates the three branches of UPR signaling, PKR-like ER kinase (PERK), activating transcription factor 6 (ATF6), and inositol-requiring enzyme 1 (IRE-1), to favor viral replication. HCMV infection activated the eIF2␣ kinase PERK; however, the amount of phosphorylated eIF2␣ was limited and translation attenuation did not occur. Interestingly, translation of select mRNAs, which is dependent on eIF2␣ phosphorylation, did occur, including the transcription factor ATF4, which activates genes which may benefit the infection. The endoplasmic reticulum stress-induced activation of the transcription factor ATF6 was suppressed in HCMV-infected cells; however, specific chaperone genes, normally activated by ATF6, were activated by a virus-induced, ATF6-independent mechanism. Lastly, HCMV infection activated the IRE-1 pathway, as indicated by splicing of Xbp-1 mRNA. However, transcriptional activation of the XBP-1 target gene EDEM (ER degradation-enhancing ␣-mannosidase-like protein, a protein degradation factor) was inhibited. These results suggest that, although HCMV infection induces the unfolded protein response, it modifies the outcome to benefit viral replication.Human cytomegalovirus (HCMV) is a betaherpesvirus which can cause significant medical problems in individuals with immature or compromised immune systems. The genome of HCMV is 230 kb of double-stranded DNA with the potential to encode over 200 proteins. Like that of other herpesviruses, HCMV viral gene expression occurs in an ordered temporal pattern having immediate-early, early, delayed-early, and late kinetics, with increasing viral protein synthesis over time.

؎ 5%, and 97% ؎ 5% of TG cell cultures, respectively (means ؎ standard deviations). In contrast, vectors that express wild-type OBP or mutant forms of ICP0, OBP, or VP16 induced reactivation in 5% ؎ 5%, 8% ؎ 0%, 0% ؎ 0%, and 13% ؎ 6% of TG cell cultures, respectively. In control infections, an adenovirus vector expressed green fluorescent protein efficiently in TG neurons but did not induce HSV-1 reactivation. Therefore, expression of ICP0, ICP4, or VP16 is sufficient to induce HSV-1 reactivation in latently infected TG cell cultures. We conclude that this system provides a powerful tool for determining which cellular and viral proteins are sufficient to induce HSV-1 reactivation from neuronal latency.The life cycle of herpes simplex virus type 1 (HSV-1) in humans can be divided into three phases: (i) productive replication of virus at the site of primary infection, (ii) establishment and maintenance of latency in sensory neurons, and (iii) periodic reactivation of viral infection from neuronal latency. The first phase, productive replication, is accurately reproduced in vitro in mammalian cell lines, and thus the molecular events that occur during productive HSV-1 replication have been studied extensively (44). The second and third phases of the HSV-1 life cycle, latency and reactivation, respectively, have been experimentally reproduced in animals such as mice, guinea pigs, and rabbits. These models were instrumental in identifying sensory neurons of the peripheral nervous system as the primary sites of HSV-1 latency (52), identifying and characterizing the latency-associated transcripts (LATs) (43,53), and investigating the physiological stimuli that induce HSV-1 reactivation (19,28,48). Because of the problems associated with conducting molecular studies in animals, however, it has proven difficult for investigators to move beyond descriptive and phenomenological observations. Therefore, the molecular mechanisms that control HSV-1 latency and reactivation remain to be elucidated.Primary trigeminal ganglion (TG) cell cultures were developed as an alternative model in which to study 29,36). Although HSV-1 latency is established in mice by conventional methods in this model (18,28,48), reactivation is analyzed ex vivo in dissociated cultures of latently infected TG cells. Monolayer cultures are treated transiently with acyclovir (ACV) or other antiviral drugs to repress reactivation during culture establishment (16,17,36), and latently infected, nondividing neurons are randomly distributed among dividing support cells (16). After removal of antiviral drugs, reactivation of latent HSV-1 can be induced in 70 to 95% of TG cell cultures by heat stress, and neurons have been shown

Cytochrome P450 2D6 genetic polymorphisms had no discernible impact on exposure to desvenlafaxine after desvenlafaxine administration; in contrast, compared with an EM phenotype, a PM phenotype had a significant effect on venlafaxine and desvenlafaxine plasma concentrations after venlafaxine ER administration. This reduced pharmacokinetic variability of desvenlafaxine may translate into better uniformity of response for patients receiving desvenlafaxine versus venlafaxine, but additional studies are required to test this hypothesis.

ABSTRACT:A number of antidepressants inhibit the activity of the cytochrome P450 2D6 enzyme system, which can lead to drug-drug interactions. Based on its metabolic profile, desvenlafaxine, administered as desvenlafaxine succinate, a new serotonin-norepinephrine reuptake inhibitor, is not expected to have an impact on activity of CYP2D6. This single-center, randomized, open-label, four-period, crossover study was undertaken to evaluate the effect of multiple doses of desvenlafaxine (100 mg/day, twice the recommended therapeutic dose for major depressive disorder in the United States) and duloxetine (30 mg b.i.d.) on the pharmacokinetics (PK) of a single dose of desipramine (50 mg). A single dose of desipramine was given first to assess its PK. Desvenlafaxine or duloxetine was then administered, in a crossover design, so that steady-state levels were achieved; a single dose of desipramine was then coadministered. The geometric least-square mean ratios (coadministration versus desipramine alone) for area under the plasma concentration versus time curve (AUC) and peak plasma concentrations (C max ) of desipramine and 2-hydroxydesipramine were compared using analysis of variance. Relative to desipramine alone, increases in AUC and C max of desipramine associated with duloxetine administration (122 and 63%, respectively) were significantly greater than those associated with desvenlafaxine (22 and 19%, respectively; P < 0.001). Duloxetine coadministered with desipramine was also associated with a decrease in 2-hydroxydesipramine C max that was significant compared with the small increase seen with desvenlafaxine and desipramine (؊24 versus 9%; P < 0.001); the difference between changes in 2-hydroxydesipramine AUC did not reach statistical significance (P ‫؍‬ 0.054). Overall, desvenlafaxine had a minimal impact on the PK of desipramine compared with duloxetine, suggesting a lower risk for CYP2D6-mediated drug interactions.Concomitant use of a drug that affects the activity of the same cytochrome P450 (P450) enzyme system responsible for biotransformation of another drug can lead to significant elevations in plasma concentration and potentially important drug-drug interactions (Preskorn and Flockhart, 2004). Such interactions may be associated with poor tolerability or increased risk for toxicity. In addition, for drugs requiring biotransformation via P450 enzymes from an inactive/less active parent compound to a pharmacologically active metabolite, drug interactions may manifest as a reduction in efficacy (Stearns et al., 2003;Preskorn and Flockhart, 2004;Preskorn and Werder, 2006). Drug interactions have an impact on clinical care and may create the need for dose adjustments, consideration of different therapeutic options, or other management strategies.Several antidepressants are known to inhibit CYP2D6 activity (Zanger et al., 2004). The selective serotonin reuptake inhibitors are associated with varying degrees of CYP2D6 inhibition. For example, paroxetine and fluoxetine strongly inhibit CYP2D6 (K i of 2.0 and 3.0 ...

We previously reported that human cytomegalovirus (HCMV) infection induces endoplasmic reticulum (ER) stress, resulting in activation of the unfolded protein response (UPR). Although some normal consequences of UPR activation (e.g., translation attenuation) are detrimental to viral infection, we have previously shown that HCMV infection adapts the UPR to benefit the viral infection (14). For example, UPR-induced translation attenuation is inhibited by viral infection, while potentially beneficial aspects of the UPR are maintained. In the present work, we tested the ability of HCMV to overcome a robust induction of the UPR by the drugs thapsigargin and clotrimazole (CLT), which disrupt ER calcium homeostasis. A 24-h treatment with these drugs beginning at 48, 72, or 96 h postinfection (hpi) completely inhibited further production of infectious virions. HCMV could not overcome the inhibition of global translation by CLT; however, between 48 and 72 hpi, HCMV overcame translational inhibition caused by thapsigargin. Despite the restoration of translation in thapsigargin, the accumulation of immediate-early and early gene products was modestly retarded (50% or less), whereas the accumulation of an early-late and late gene product was significantly retarded. Electron microscopic analysis shows that the drugs severely disrupt the maturation of HCMV virions. This can be accounted for by both the retarded accumulation of late gene products and the drug-induced depletion of ER calcium, which disrupts critical cellular functions needed for maturation.