The small heterodimer partner (SHP; NROB2), a member of the nuclear receptor superfamily, contributes to the biological regulation of several major functions of the liver. However, the role of SHP in cellular proliferation and tumorigenesis has not been investigated before. Here we report that SHP negatively regulates tumorigenesis both in vivo and in vitro. SHP−/− mice aged 12 to 15 months old developed spontaneous hepatocellular carcinoma, which was found to be strongly associated with enhanced hepatocyte proliferation and increased cyclin D1 expression. In contrast, overexpressing SHP in hepatocytes of SHP-transgenic mice reversed this effect. Embryonic fibroblasts lacking SHP showed enhanced proliferation and produced increased cyclin D1 messenger RNA and protein, and SHP was shown to be a direct negative regulator of cyclin D1 gene transcription. The immortal SHP−/− fibroblasts displayed characteristics of malignant transformed cells and formed tumors in nude mice.
These results provide first evidence that SHP plays tumor suppressor function by negatively regulating cellular growth.
Aberrant epigenetic alterations during development may result in long-term epigenetic memory and have a permanent effect on the health of subjects. Constitutive androstane receptor (CAR; NR1I3) is a central regulator of drug/xenobiotic metabolism. Here, we report that transient neonatal activation of CAR results in epigenetic memory and a permanent change of liver drug metabolism. CAR activation by neonatal exposure to a CAR-specific ligand, 1,4-bis[2-(3,5-dichloropyridyloxy)] benzene (TCPOBOP) led to persistently induced expression of the CAR target genes Cyp2B10 and Cyp2C37 throughout the life of exposed mice. These mice showed a permanent reduction in sensitivity to zoxazolamine treatment as adults. Compared with control groups, the induction of Cyp2B10 and Cyp2C37 in hepatocytes isolated from these mice was more sensitive to low concentrations of the CAR agonist TCPOBOP. Accordingly, neonatal activation of CAR led to a permanent increase of histone 3 lysine 4 (H3K4) mono-, di- and trimethylation and decrease of H3K9 trimethylation within the Cyp2B10 locus. Transcriptional coactivator ASC-2 and histone demethylase JMJD2d participated in this CAR-dependent epigenetic switch.
Neonatal activation of CAR results in epigenetic memory and a permanent change of liver drug metabolism.
CAR; nuclear receptor; epigenetic memory; drug metabolism; histone methylation
The hepatotoxicity of thioacetamide (TA) has been known since 1948. In rats, single doses cause centrilobular necrosis accompanied by increases in plasma transaminases and bilirubin. To elicit these effects TA requires oxidative bioactivation leading first to its S-oxide (TASO) and then to its chemically reactive S,S-dioxide (TASO2) which ultimately modifies amine-lipids and proteins. To generate a suite of liver proteins adducted by TA metabolites for proteomic analysis, and to reduce the need for both animals and labeled compounds, we treated isolated hepatocytes directly with TA. Surprisingly, TA was not toxic at concentrations up to 50 mM for 40 hr. On the other hand, TASO was highly toxic to isolated hepatocytes as indicated by LDH release, cellular morphology and vital staining with Hoechst 33342/propidium iodide. TASO toxicity was partially blocked by the CYP2E1 inhibitors diallyl sulfide and 4-methylpyrazole, and was strongly inhibited by TA. Significantly, we found that hepatocytes produce TA from TASO relatively efficiently by back-reduction. The covalent binding of [14C]-TASO is inhibited by unlabeled TA which acts as a “cold-trap” for [14C]-TA and prevents its re-oxidation to [14C]-TASO. This in turn increases the net consumption of [14C]-TASO despite the fact that its oxidation to TASO2 is inhibited. The potent inhibition of TASO oxidation by TA, coupled with the back-reduction of TASO and its futile redox cycling with TA may help explain phenomena previously interpreted as “saturation toxicokinetics” in the in vivo metabolism and toxicity of TA and TASO. The improved understanding of the metabolism and covalent binding of TA and TASO facilitates the use of hepatocytes to prepare protein adducts for target protein identification.
Up to 20% of people initiating antiretroviral therapy (ART) in sub- Saharan Africa die during the first year of treatment. Understanding the clinical conditions associated with mortality could potentially lead to effective interventions to prevent these deaths.
We examined data from participants aged ≥18 years in the Home-Based AIDS Care project in Tororo, Uganda, to describe mortality over time and to determine clinical conditions associated with death. Survival analysis was used to examine variables associated with mortality at baseline and during follow-up.
A total of 112 (9.4%) deaths occurred in 1,132 subjects (73% women) during a median of 3.0 years of ART. Mortality was 15.9 per 100 person-years (PYR) during the first 3 months and declined to 0.3 per 100 PYR beyond 24 months after ART initiation. Tuberculosis (TB) was the most common condition associated with death (21% of deaths), followed by Candida disease (15%). In 43% of deaths no specific clinical diagnosis was identified. Deaths within 3 months after ART initiation were associated with WHO clinical stage III or IV at baseline, diagnosis of TB at baseline, a diagnosis of a non-TB opportunistic infection (OI) in follow-up and a body mass index (BMI) ≤ 17 kg/m2 during follow-up. Mortality after 3 months of ART was associated with CD4 cell counts <200 cells/µL, a diagnosis of TB or other OI, adherence to therapy <95%, and low hemoglobin levels during follow-up.
Potentially remediable conditions and preventable infections were associated with mortality while receiving ART in Uganda.
antiretroviral therapy; mortality; Africa; anemia; tuberculosis
Single-span transmembrane (TM) helices have structural and functional roles well beyond serving as mere anchors to tether water-soluble domains in the vicinity of the membrane. They frequently direct the assembly of protein complexes and mediate signal transduction in ways analogous to small modular domains in water-soluble proteins. This review highlights different sequence and structural motifs that direct TM assembly and discusses their roles in diverse biological processes. We believe that TM interactions are potential therapeutic targets, as evidenced by natural proteins that modulate other TM interactions and recent developments in the design of TM-targeting peptides.
Signal transduction across biological membranes is central to life. This process generally happens through communication between different domains and hierarchical coupling of information. Here, we review structural and thermodynamic principles behind transmembrane (TM) signal transduction and discuss common themes. Communication between signaling domains can be understood in terms of thermodynamic and kinetic principles, and complex signaling patterns can arise from simple wiring of thermodynamically coupled domains. We relate this to functions of several signal transduction systems: the M2 proton channel from influenza A virus, potassium channels, integrin receptors, and bacterial kinases. We also discuss key features in the structural rearrangements responsible for signal transduction in these systems.
signal transduction; allostery; transmembrane signaling; receptor; ion channel
The feasibility, use, and acceptability of text messages to track methamphetamine use and promote antiretroviral treatment (ART) adherence among HIV-infected methamphetamine users was examined. From an ongoing randomized controlled trial, 30-day text response rates of participants assigned to the intervention (individualized texting for adherence building (iTAB), n = 20) were compared to those in the active comparison condition (n = 9). Both groups received daily texts assessing methamphetamine use, and the iTAB group additionally received personalized daily ART adherence reminder texts. Response rate for methamphetamine use texts was 72.9% with methamphetamine use endorsed 14.7% of the time. Text-derived methamphetamine use data was correlated with data from a structured substance use interview covering the same time period (P < 0.05). The iTAB group responded to 69.0% of adherence reminder texts; among those responses, 81.8% endorsed taking ART medication. Standardized feedback questionnaire responses indicated little difficulty with the texts, satisfaction with the study, and beliefs that future text-based interventions would be helpful. Moreover, most participants believed the intervention reduced methamphetamine use and improved adherence. Qualitative feedback regarding the intervention was positive. Future studies will refine and improve iTAB for optimal acceptability and efficacy. This trial is registered with ClinicalTrials.gov NCT01317277.
Clinical hypothyroidism affects various metabolic processes including drug metabolism. CYP2B and CYP3A are important cytochrome P450 drug metabolizing enzymes that are regulated by the xenobiotic receptors constitutive androstane receptor (CAR, NR1I3) and pregnane X receptor (PXR, NR1I2). We evaluated the regulation of the hepatic expression of CYPs by CAR and PXR in the hypothyroid state induced by a low-iodine diet containing 0.15% propylthiouracil. Expression of Cyp3a11 was suppressed in hypothyroid C57BL/6 wild type (WT) mice and a further decrement was observed in hypothyroid CAR-/- mice, but not in hypothyroid PXR-/- mice. In contrast, expression of Cyp2b10 was induced in both WT and PXR-/- hypothyroid mice, and this induction was abolished in CAR-/- mice and in and CAR-/- PXR-/- double knockouts. CAR mRNA expression was increased by hypothyroidism, while PXR expression remained unchanged. Carbamazepine (CBZ) is a commonly used antiepileptic that is metabolized by CYP3A isoforms. After CBZ treatment of normal chow fed mice, serum CBZ levels were highest in CAR-/- mice and lowest in WT and PXR-/- mice. Hypothyroid WT or PXR-/- mice survived chronic CBZ treatment, but all hypothyroid CAR-/- and CAR-/- PXR-/- mice died, with CAR-/-PXR-/- mice surviving longer than CAR-/- mice (12.3 ±3.3 days vs. 6.3 ±2.1 days, p=0.04). All these findings suggest that hypothyroid status affects xenobiotic metabolism, with opposing responses of CAR and PXR and their CYP targets that can cancel each other out, decreasing serious metabolic derangement in response to a xenobiotic challenge.
thyroid hormone; cytochrome P450; xenobiotic receptor
Sestrin-2 is involved in p53-dependent antioxidant defenses and in the maintenance of metabolic homeostasis. We hypothesize that sestrin-2 expression is altered in the brains of subjects diagnosed with human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) due to neuronal oxidative stress. We studied sestrin-2 immunoreactivity in 42 isocortex sections from HIV-1-infected subjects compared to 18 age-matched non-HIV controls and 19 advanced Alzheimer's disease (AD) cases. With HIV infection, the sestrin-2 immunoreactivity pattern shifted from neuropil predominance (N) to neuropil and neuronal-soma co-dominance (NS) and neuronalsoma predominance (S; P < 0.0001, Chi-square test for linear trend). Among HIV cases showing the NS or S pattern, HAND cases were preferentially associated with the S pattern (n = 10 of 20) compared to cognitively intact cases (n = 1 of 11; P = 0.047, Fisher's exact test). In AD brains, sestrin-2 immunoreactivity was mostly intense in the neuropil and co-localized with phospho-Tau immunoreactivity in a subset of neurofibrillary lesions. Phospho-Tau-immunoreactive neurofibrillary lesions were rare in HIV cases and their occurrence was not associated with HAND. Levels of isocortical 8-hydroxy-deoxyguanosine (marker of nucleic acid oxidation) immunoreactivity were not significantly altered in HAND cases compared to cognitively intact HIV cases. In conclusion, the sestrin-2 immunoreactivity redistribution to neuronal soma in HAND suggests unique involvement of sestrin-2 in the pathophysiology of HAND, which is different from the role of sestrin-2 in AD pathogenesis. Alternatively, the difference in sestrin-2 immunoreactivity distribution between HAND and AD may be related to different degrees of severity or stages of oxidative stress.
Alzheimer's disease; HIV dementia; Neurofibrillary pathology; Oxidative stress; SESN2
Individuals of Asian heritage represent the largest ethnic minority in Canada. Approximately 10% of the new HIV diagnoses in men in British Columbia occur among Asian-Canadians. However, the HIV risk patterns of Asian men who have sex with men (MSM) have not been extensively studied.
Participants aged ≥ 19 years were enrolled in a venue-based HIV serobehavioural survey of MSM in Vancouver, Canada. We compared the demographic characteristics, risk behaviours, and prevalence of HIV and other sexual and blood borne infections between Asian and non-Asian MSM using bivariate analysis and logistic regression confounder modelling.
Amongst 1132 participants, 110 (9.7%) self-identified as Asian. Asian participants were younger than non-Asian participants (median age 29 vs. 32 years; p < 0.001), but otherwise did not differ from other study participants. HIV prevalence was lower among Asian MSM compared to Non-Asian MSM (3.7% vs 19.0%, p <0.001). Among men who self-reported as HIV negative or unknown we found no differences in unprotected anal intercourse (UAI) with a discordant or unknown serostatus partner in the previous six months (11 vs. 13%; p = 0.503). However, Asian MSM were less likely to report ever using injection drugs (10.8% vs. 19.2%; p = 0.043) or using alcohol before having sex (52% vs. 64.4%; p = 0.017).
Asian MSM in our study reported similar rates of UAI as non-Asian MSM, but had a lower prevalence of HIV infection. Other factors, such as the use of drugs and alcohol, in relation to sex, may partly explain these differences. However this requires further investigation.
HIV; Homosexuality; Men who have sex with men; Asian
With widespread availability of paediatric ART and improved access to PMTCT, it is important to monitor the impact on paediatric HIV-related hospital admissions and in-hospital mortality in South Africa.
Over a 15 year period, 4 independant surveillance studies were conducted in the paediatric wards at Chris Hani Baragwanath Hospital in Soweto, South Africa (1996, 2005, 2007 and late 2010 to early 2011). Trends in HIV prevalence and HIV-related mortality were evaluated.
HIV prevalence was similar during the first 3 time periods: 26.2% (1996), 31.7% (2005) and 29.5% (2007) p>0.10, but was lower in 2010–11 (19.3%; p=0.0005). Median age of the children admitted with HIV increased in the latter time periods from 9.13 (IQR 3.6 – 28.8), to 10.0 (3.0 – 44.5) (p>0.10) and 18.0 (6.2 – 69.8) months (p=0.048). Median admission WAZ-scores were similar (<−3 SD) for the latter 3 time periods. Admission CD4 percentage increased from 0.0% (0.0 – 9.4) 2005, to 15.0% (8.2 – 22.8) 2007 (p<0.0001) and was 18.7% (9.6 – 24.7) in 2010–11 (p>0.10). Mortality among all vs. HIV-infected admissions was 63/565 (11.2%) and 43/179 (24.0%) in 2005, 91/1510 (6.0%) and 53/440 (12.0%) in 2007 and 18/429 (4.2%) and 9/73 (12.3%) in 2010–11.
HIV-prevalence and mortality among paediatric admissions is decreasing. This is likely a result of improved PMTCT and wider ART coverage. Continued effort to improve PMTCT coverage and identify and treat younger and older HIV-infected children is required to further reduce HIV-related morbidity and mortality.
To assess efficacy and safety of once-daily 8 or 12 mg perampanel, a noncompetitive α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor antagonist, when added to concomitant antiepileptic drugs (AEDs) in the treatment of drug-resistant partial-onset seizures.
This was a multicenter, double-blind, placebo-controlled trial (ClinicalTrials.gov identifier: NCT00699972). Patients (≥12 years, with ongoing seizures despite 1–3 AEDs) were randomized (1:1:1) to once-daily perampanel 8 mg, 12 mg, or placebo. Following baseline (6 weeks), patients entered a 19-week double-blind phase: 6-week titration (2 mg/week increments to target dose) followed by a 13-week maintenance period. Percent change in seizure frequency was the primary endpoint; 50% responder rate was the primary endpoint for EU registration.
Of 388 patients randomized and treated, 387 provided seizure frequency data. Using this intent-to-treat population over the double-blind phase, the median percent change in seizure frequency was −21.0%, −26.3%, and −34.5% for placebo and perampanel 8 and 12 mg, respectively (p = 0.0261 and p = 0.0158 for 8 and 12 mg vs placebo, respectively). Fifty percent responder rates during the maintenance period were 26.4%, 37.6%, and 36.1%, respectively, for placebo, perampanel 8 mg, and perampanel 12 mg; these differences were not statistically significant for 8 mg (p = 0.0760) or 12 mg (p = 0.0914). Sixty-eight (17.5%) patients discontinued, including 40 (10.3%) for adverse events. Most frequent treatment-emergent adverse events were dizziness, somnolence, irritability, headache, fall, and ataxia.
This trial demonstrated that once-daily, adjunctive perampanel at doses of 8 or 12 mg improved seizure control in patients with uncontrolled partial-onset seizures. Doses of perampanel 8 and 12 mg were safe, and tolerability was acceptable.
Classification of evidence:
This study provides Class I evidence that once-daily 8 and 12 mg doses of adjunctive perampanel are effective in patients with uncontrolled partial-onset seizures.
Among English-speaking adults, HIV-associated neuropsychological (NP) impairments have been associated with problems in everyday functioning, including ability to function at work and drive an automobile. Latinos account for a disproportionate number of HIV/AIDS cases nationwide, and a significant segment of this population is primarily Spanish speaking. We have previously developed an assessment that evaluates English-speakers on a variety of instrumental activities of daily living. In this pilot study, we used Spanish-language translations of our functional battery to investigate the cultural relevance of such measures, and to explore relationships between NP status and ability to perform important everyday tasks in HIV-infected Spanish-speakers. Sixteen HIV-infected monolingual Spanish-speaking adults received comprehensive, Spanish language NP testing and functional assessments included the following domains: Medication Management, Cooking, Finances, Shopping, and Restaurant Scenario. Results revealed that most of the functional tasks appeared culturally relevant and appropriate with minor modifications. NP-impaired participants were significantly more functionally impaired compared to NP-normals (88% vs. 13%, p<.01). Performances on the functional assessment and the NP battery were also related to indicators of real world functioning, including employment status and quality of life. These results, though preliminary, suggest that Spanish language functional assessments are potentially valid tools for detecting everyday functioning deficits associated with NP impairments in HIV-infected Spanish-speakers.
Unemployment rates are high among chronic methamphetamine (MA) users and carry a significant economic burden, yet little is known about the neurocognitive and psychiatric predictors of employment in this vulnerable population.
The present study examined this issue in 63 participants with recent MA dependence and 47 comparison subjects without histories of MA use disorders. All participants completed a comprehensive neurocognitive, psychiatric and neuromedical evaluation. Individuals with HIV infection, severe neuropsychological or psychiatric conditions that might affect cognition (e.g., seizure disorder, schizophrenia), or a positive Breathalyzer or urine toxicology screen on the day of testing were excluded.
Consistent with previous research, a logistic regression revealed MA dependence as a significant, independent predictor of full-time unemployment status. Within the MA-dependent sample, greater impairment in global neurocognitive functioning and history of injection drug use emerged as significant independent predictors of unemployment status. The association between worse global cognitive functioning and unemployment was primarily driven by deficits in executive functions, learning, verbal fluency, and working memory.
These findings indicate that neurocognitive deficits play a significant role in the higher unemployment rates of MA-dependent individuals, and highlight the need for vocational rehabilitation and supported employment programs that assess and bolster cognitive skills in this population.
Functional status; Substance abuse; Cognitive impairment; Neuropsychological assessment; Employment
FK506 binding protein (FKBP)-51 and FKBP52 act as molecular chaperones to control glucocorticoid receptor (GR) sensitivity. Dysregulation of proteins involved in GR-mediated signaling can lead to maladaptive stress response and aging-related cognitive decline. As HIV infection is related to chronic stress, we hypothesized that altered cortical expression of these proteins was associated with HIV-associated neurocognitive disorders (HAND). We used quantitative immunohistochemistry to assess expression levels of these proteins in the mid-frontal gyrus of 55 HIV-infected subjects free of cerebral opportunistic diseases compared to 20 age-matched non-HIV controls. The immunoreactivity normalized to the neuroanatomic area measured (IRn) for FKBP51 was increased in HIV subjects both in the cortex and subcortical white matter (p<0.0001, U test), while no significant alterations were observed for GR or FKBP52. Notably, the cortical FKBP51 IRn was higher in HAND subjects than in cognitively normal HIV subjects (p=0.02, U test). There was also a trend for increasing cortical FKBP51 IRn with the increasing severity of HAND (p=0.08, Kruskal-Wallis test). No significant changes in FKBP51 IRn were found with respect to hepatitis C virus infection, lifetime methamphetamine use, or antiretroviral treatment in HIV subjects. In conclusion, the increased cortical expression of FKBP51 (an inhibitor for GR activity) might represent negative feedback in an attempt to reduce GR sensitivity in the setting of chronic stress-induced elevation of GR-mediated signaling inherent in HIV infection. The further increased FKBP51 expression might lead to maladaptive stress response and HAND.
FKBP4; FKBP5; HIV dementia; Immunophilin; NR3C1
Episodic memory deficits are common in HIV infection and bipolar disorder, but patient insight into such deficits remains unclear. Thirty-four HIV-infected individuals without bipolar disorder l(HIV+/BD−) and 47 HIV+ individuals with comorbid bipolar disorder (HIV+/BD+) were administered the Hopkins Verbal Learning Test-Revised and the Brief Visuospatial Memory Test-Revised to examine objective learning/memory functioning. Subjective memory complaints were assessed via the memory subscale of the Patient’s Assessment of Own Functioning Inventory. HIV+/BD+ individuals performed poorer on tests of visual learning and visual/verbal recall compared to HIV+/BD− participants (ps<0.05). Memory complaints only predicted verbal learning (at a trend level, p=0.10) and recall (p=0.03) among the HIV+/BD− individuals. Memory complaints were not associated with memory performance within the HIV+/BD+ group (ps>0.10). Memory complaints were associated with affective symptoms in both groups. These complaints were also predictive of immunosuppression, higher unemployment, and greater dependence on Activities of Daily Living among the HIV+/BD+ individuals (ps<0.05). Awareness of memory abilities was particularly poor among HIV+/BD+ individuals (i.e., objective learning/memory did not correspond to reported complaints), which has important implications for the capacity of these individuals to engage in error-monitoring and compensatory strategies in daily life. Memory complaints are associated with depressed mood regardless of group membership. Among HIV+/BD+ individuals, these complaints may also signify worse HIV disease status and problems with everyday functioning. Clinicians and researchers should be cognizant of what these complaints indicate in order to lead treatment most effectively; use of objective neurocognitive assessments may still be warranted when working with these populations.
Self report; Infectious Diseases; Affective Disorders; Episodic Memory; Cognition
Aggregated α-synuclein and the point mutations Ala30Pro and Ala53Thr of α-synuclein are associated with Parkinson’s disease. The physiological roles of α-synuclein and methionine oxidation of the α-synuclein protein structure and function are not fully understood. Methionine sulfoxide reductase A (MsrA) reduces methionine sulfoxide residues and functions as an antioxidant. To monitor the effect of methionine oxidation to α-synuclein on basic cellular processes, α-synucleins were expressed in msrA null mutant and wild-type yeast cells. Protein degradation was inhibited in the α-synuclein-expressing msrA null mutant cells compared to α-synuclein-expressing wild-type cells. Increased inhibition of degradation and elevated accumulations of fibrillated proteins were observed in SynA30P-expressing msrA null mutant cells. Additionally, methionine oxidation inhibited α-synuclein phosphorylation in yeast cells and in vitro by casein kinase 2. Thus, a compromised MsrA function combined with α-synuclein overexpression may promote processes leading to synucleinopathies.
Oxidative stress; Posttranslation modification; Neurodegenerative diseases; Parkinson’s disease; Antioxidants; Protein aggregation; Yeast; Synuclein
Currently, the majority of animal models that are used to study biofilm-related infections utilize planktonic bacterial cells as initial inocula to produce positive signals of infection in biomaterials studies. However, the use of planktonic cells has potentially led to inconsistent results in infection outcomes. In this study, well-established biofilms of methicillin-resistant Staphylococcus aureus (MRSA) were grown and used as initial inocula in an animal model of a Type IIIB open fracture. The goal of the work was to establish, for the first time, a repeatable model of biofilm implant-related osteomyelitis wherein biofilms were used as initial inocula to test combination biomaterials. Results showed that 100% of animals that were treated with biofilms developed osteomyelitis, whereas 0% of animals not treated with biofilm developed infection. The development of this experimental model may lead to an important shift in biofilm and biomaterials research by showing that when biofilms are used as initial inocula, they may provide additional insights into how biofilm-related infections in the clinic develop and how they can be treated with combination biomaterials to eradicate and/or prevent biofilm formation.
Planktonic; Biofilm; Initial Inocula; Animal Model; Infection
Perceptual decision making is prone to errors, especially near threshold. Physiological, behavioural and modeling studies suggest this is due to the intrinsic or ‘internal’ noise in neural systems, which derives from a mixture of bottom-up and top-down sources. We show here that internal noise can form the basis of perceptual decision making when the external signal lacks the required information for the decision. We recorded electroencephalographic (EEG) activity in listeners attempting to discriminate between identical tones. Since the acoustic signal was constant, bottom-up and top-down influences were under experimental control. We found that early cortical responses to the identical stimuli varied in global field power and topography according to the perceptual decision made, and activity preceding stimulus presentation could predict both later activity and behavioural decision. Our results suggest that activity variations induced by internal noise of both sensory and cognitive origin are sufficient to drive discrimination judgments.
Oltipraz (OPZ) is a well known inducer of NAD(P)H:quinone oxidoreductase (NQO1) along with other enzymes that comprise the nuclear factor E2-related factor 2 (Nrf2) battery of detoxification genes. However, OPZ treatment also induces expression of CYP2B, a gene regulated by the constitutive androstane receptor (CAR). Therefore, this study was designed to determine whether OPZ induces gene expression in the mouse liver through activation of CAR in addition to Nrf2. OPZ increased the mRNA expression of both Cyp2b10 and Nqo1 in C57BL/6 mouse livers. As expected, in livers from Nrf2−/− mice, OPZ induction of Nqo1 was reduced, indicating Nqo1 induction is dependent on Nrf2 activation, whereas Cyp2b10 induction was unchanged. The robust induction of Cyp2b10 by OPZ in wild-type mice was completely absent in CAR−/− mice, revealing a CAR-dependent induction by OPZ. OPZ also induced transcription of the human CYP2B6 promoter-reporter containing the phenobarbital (PB) responsive element in mouse liver using an in vivo transcription assay. Additionally, OPZ induced in vivo nuclear accumulation of CAR at 3 h but, as with PB, was unable to reverse androstanol repression of mouse CAR constitutive activity in transiently transfected HepG2 cells. In summary, OPZ induces expression of Cyp2b10 and Nqo1 via the activation of CAR and Nrf2, respectively.
There is limited available data on the strain diversity of M tuberculosis in Peru, though there may be interesting lessons to learn from a setting where multidrug resistant TB has emerged as a major problem despite an apparently well-functioning DOTS control programme.
Spoligotyping was undertaken on 794 strains of M tuberculosis collected between 1999 and 2005 from 553 community-based patients and 241 hospital-based HIV co-infected patients with pulmonary tuberculosis in Lima, Peru. Phylogenetic and epidemiologic analyses permitted identification of clusters and exploration of spoligotype associations with drug resistance.
Mean patient age was 31.9 years, 63% were male and 30.4% were known to be HIV+. Rifampicin mono-resistance, isoniazid mono-resistance and multidrug resistance (MDR) were identified in 4.7%, 8.7% and 17.3% of strains respectively. Of 794 strains from 794 patients there were 149 different spoligotypes. Of these there were 27 strains (3.4%) with novel, unique orphan spoligotypes. 498 strains (62.7%) were clustered in the nine most common spoligotypes: 16.4% SIT 50 (clade H3), 12.3% SIT 53 (clade T1), 8.3% SIT 33 (LAM3), 7.4% SIT 42 (LAM9), 5.5% SIT 1 (Beijing), 3.9% SIT 47 (H1), 3.0% SIT 222 (clade unknown), 3.0% SIT1355 (LAM), and 2.8% SIT 92 (X3). Amongst HIV-negative community-based TB patients no associations were seen between drug resistance and specific spoligotypes; in contrast HIV-associated MDRTB, but not isoniazid or rifampicin mono-resistance, was associated with SIT42 and SIT53 strains.
Two spoligotypes were associated with MDR particularly amongst patients with HIV. The MDR-HIV association was significantly reduced after controlling for SIT42 and SIT53 status; residual confounding may explain the remaining apparent association. These data are suggestive of a prolonged, clonal, hospital-based outbreak of MDR disease amongst HIV patients but do not support a hypothesis of strain-specific propensity for the acquisition of resistance-conferring mutations.
Heat shock protein 90 (Hsp90) represents a promising therapeutic target for the treatment of cancer and other diseases. Unfortunately, results from clinical trials have been disappointing as off-target effects and toxicities have been observed. These detriments may be a consequence of pan-Hsp90 inhibition, as all clinically evaluated Hsp90 inhibitors simultaneously disrupt all four human Hsp90 isoforms. Using a structure-based approach, we designed an inhibitor of Grp94, the ER-resident Hsp90. The effect manifested by compound 2 on several Grp94 and Hsp90α/β (cytosolic isoforms) clients were investigated. Compound 2 prevented intracellular trafficking of the Toll receptor, inhibited the secretion of IGF-II, affected the conformation of Grp94, and suppressed Drosophila larval growth, all Grp94-dependent processes. In contrast, compound 2 had no effect on cell viability or cytosolic Hsp90α/β client proteins at similar concentrations. The design, synthesis, and evaluation of 2 are described herein.
Volatile anaesthetic agents are known to cause acute hepatitis and fulminant hepatic failure in susceptible individuals. Four patients were identified with prolonged liver injury due to volatile anaesthetic-induced hepatitis. Three had liver biopsy confirmation and all gave blood for specific diagnostic tests (TFA and CYP 2E1 IgG4 antibodies). The Roussel Uclaf Causality Assessment Method (RUCAM) drug causality scale was used to determine the likelihood of volatile anaesthetics causing the chronic liver injury. We describe four cases of volatile anaesthetic hepatitis in which three evolved into chronic hepatitis. The fourth followed a more typical pattern of acute hepatitis; however, resolution took a few months. These cases all occurred with modern volatile anaesthetics, predominantly sevoflurane, and all cases were proven with specific antibody tests, liver histology and a drug causality scale. This is the first report of chronic liver injury due to volatile anaesthetic exposure.