Neora Pick

The Mycobacterium tuberculosis protein serine/threonine kinase PknG is linked to cellular glutamate/glutamine levels and is important for growth in vivo

Summary The function of the Mycobacterium tuberculosis eukaryotic‐like protein serine/threonine kinase PknG was investigated by gene knock‐out and by expression and biochemical analysis. The pknG gene (Rv0410c), when cloned and expressed in Escherichia coli, encodes a functional kinase. An in vitro kinase assay of the recombinant protein demonstrated that PknG can autophosphorylate its kinase domain as well as its 30 kDa C‐terminal portion, which contains a tetratricopeptide (TPR) structural signalling motif. Western analysis revealed that PknG is located in the cytosol as well as in mycobacterial membrane. The pknG gene was inactivated by allelic exchange in M. tuberculosis. The resulting mutant strain causes delayed mortality in SCID mice and displays decreased viability both in vitro and upon infection of BALB/c mice. The reduced growth of the mutant was more pronounced in the stationary phase of the mycobacterial growth cycle and when grown in nutrient‐depleted media. The PknG‐deficient mutant accumulates glutamate and glutamine. The cellular levels of these two amino acids reached approximately threefold of their parental strain levels. Higher cellular levels of the amine sugar‐containing molecules, GlcN‐Ins and mycothiol, which are derived from glutamate, were detected in the ΔpknG mutant. De novo glutamine synthesis was shown to be reduced by 50%. This is consistent with current knowledge suggesting that glutamine synthesis is regulated by glutamate and glutamine levels. These data support our hypothesis that PknG mediates the transfer of signals sensing nutritional stress in M. tuberculosis and translates them into metabolic adaptation.

Gaseous nitric oxide bactericidal activity retained during intermittent high-dose short duration exposure

Previously, we have shown that gaseous Nitric oxide (gNO) has great potential as an effective topical anti-infective agent for non-healing wounds due to its non-specific antimicrobial properties. These same antimicrobial attributes may be useful for pulmonary infections. However, gNO would have limited usefulness as an inhaled antimicrobial agent as continuous exposure to the concentration required for a bactericidal effect (160-200 ppm) leads to methemoglobinemia. To overcome this problem, we investigated whether a thirty minute exposure of 160 ppm every four hours would retain the same antimicrobial effect as continuous delivery. In vitro, exposure of clinical multi-drug resistant Staphylococcus aureus and Escherichia coli strains isolated from the lungs of nosocomial pneumonia patients and a lethal antibiotic-resistant strain of Pseudomonas aeruginosa, isolated from a deceased cystic fibrosis patient resulted in over a 5 log(10) reduction in bacterial load after multiple thirty minute treatments (4 cycles) every four hours to 160 ppm gNO. The intermittent regimen required 320 (SD=0)ppm h for 100% lethality whereas the continuous exposure required 800 (SD=160)ppm h. We have also shown that selection for a gNO resistant phenotype did not lead to decrease sensitivity to gNO therapy (p>0.05). In addition, no host cellular toxicity was observed in human THP-1 monocytes and macrophages following intermittent delivery of a high concentration of gNO, and the proliferation and migration of pulmonary epithelial cells was not adversely affected by the administration of intermittent high-dose gNO. These results justify further studies that should focus on whether intermittent delivery of 160 ppm of gNO every four hours can technically be administered while keeping inhaled NO(2) levels less than 2 ppm and methemoglobin saturation less than 2.5 percent.

Cohort Profile: The Canadian HIV–Hepatitis C Co-infection Cohort Study

Hepatitis C virus (HCV) has emerged as one of the most vexing health problems facing HIV-infected persons. Due largely to injection drug use (IDU),430% of HIV-infected patients are co-infected with HCV in developed countries with 10 million co-infected worldwide. In 1999, 11 194 Canadians were estimated to be co-infected and this number has likely increased substantially since. HCV infection has also increasingly been reported in HIV-positive men having sex with men (MSM) who have not used injection drugs. Since the advent of highly active antiretroviral therapy (HAART) there have been dramatic reductions in morbidity and mortality from virtually all causes of illness among HIV-infected persons. One of the glaring exceptions to this trend is death from end-stage liver disease (ESLD) with rates increasing 4to 8-fold in the post-HAART era. This excess mortality may be due, in part, to improved overall survival associated with HAART, allowing competing morbidities and mortalities that were once rarely observed. In addition, HCVassociated hepatic fibrosis has been shown to progress more rapidly in the context of HIV infection, likely due to immune dysfunction. Several other factors may be at play, including chronic hepatotoxicity related to antiretrovirals, incomplete immune recovery, heavy alcohol use and problems with access and/or adherence to HAART and HCV treatment in a population with high rates of substance use. The growing burden of chronic HCV infection is expected to result in dramatic increases in the rates of cirrhosis, liver failure, hepatocellular carcinoma, transplant needs and related annual healthcare costs in Canada and worldwide. Understanding the complex interplay between sociodemographic factors, substance use, biology and treatments that may affect outcomes in co-infection is necessary to meet the challenge of providing effective

How Generalizable Are the Results From Trials of Direct Antiviral Agents to People Coinfected With HIV/HCV in the Real World?

Trial results are used to support licensure, inform cost-effectiveness analyses, and guide clinical decision making. We found the majority of coinfected patients were not included in clinical trials of direct-acting antivirals, raising concerns about the generalizability of these trial results.

How generalizable are the results from trials of Direct Antiviral Agents to people coinfected with HIV/Hepatitis C virus in the real world?

Trial results are used to support licensure, inform cost-effectiveness analyses, and guide clinical decision making. We found the majority of coinfected patients were not included in clinical trials of direct-acting antivirals, raising concerns about the generalizability of these trial results.

Association Between Short Leukocyte Telomere Length and HIV Infection in a Cohort Study: No Evidence of a Relationship With Antiretroviral Therapy

BACKGROUND Individuals infected with human immunodeficiency virus (HIV) appear to age faster than the general population, possibly related to HIV infection, antiretroviral therapy, and/or social/environmental factors. We evaluated leukocyte telomere length (LTL), a marker of cellular aging, in HIV-infected and uninfected adults. METHODS Clinical data and blood were collected from Children and women: AntiRetrovirals and the Mechanism of Aging (CARMA) cohort study participants. Variables found to be important in univariate analysis were multivariate model candidates. RESULTS Of the 229 HIV-infected and 166 HIV-uninfected participants, 76% were women, and 71% were current/previous smokers. In a multivariate model of all participants, older age (P < .001), HIV infection (P = .04), active hepatitis C virus (HCV) infection (P = .02), and smoking (P < .003) were associated with shorter LTL. An interaction was detected, whereby smoking was associated with shorter LTL in HIV-uninfected subjects only. Among those, age and smoking (P ≤ .01) were related to shorter LTL. In 2 models of HIV-infected individuals, age (P ≤ .002) and either active HCV infection (P = .05) or peak HIV RNA ≥100 000 copies/mL (P = .04) were associated with shorter LTL, whereas other HIV disease or treatment parameters were unrelated. CONCLUSIONS Our results suggest that acquisition of HIV and viral load are primarily responsible for the association between HIV-positive status and shorter LTL. The lack of association between LTL and time since HIV diagnosis, antiretroviral treatment, or degree of immune suppression would implicate HIV infection-related factors rather than disease progression or treatment. Smoking effects on LTL appear masked by HIV, and HCV infection may accelerate LTL shortening, particularly in coinfected individuals. The effect of early therapeutic intervention on LTL in HIV and HCV infections should be evaluated.

HIV and hepatitis C virus coinfection in Canada: challenges and opportunities for reducing preventable morbidity and mortality

Hepatitis C virus (HCV) has emerged as an important health problem in the era of effective HIV treatment. However, very few data exist on the health status and disease burden of HIV/HCV‐coinfected Canadians.

Screening of Compounds Toxicity against Human Monocytic cell line-THP-1 by Flow Cytometry

The worldwide rapid increase in bacterial resistance to numerous antibiotics requires on-going development of new drugs to enter the market. As the development of new antibiotics is lengthy and costly, early monitoring of compound’s toxicity is essential in the development of novel agents. Our interest is in a rapid, simple, high throughput screening method to assess cytotoxicity induced by potential agents. Some intracellular pathogens, such as Mycobacterium tuberculosis primary site of infection is human alveolar macrophages. Thus, evaluation of candidate drugs for macrophage toxicity is crucial. Protocols for high throughput drug toxicity screening of macrophages using flow cytometry are lacking in the literature. For this application we modified a preexisting technique, propidium iodide (PI) exclusion staining and utilized it for rapid toxicity tests. Samples were prepared in 96 well plates and analyzed by flow cytometry, which allowed for rapid, inexpensive and precise assessment of compound’s toxicity associated with cell death.

A Qualitative Study Investigating the Use of a Mobile Phone Short Message Service Designed to Improve HIV Adherence and Retention in Care in Canada (WelTel BC1)

&NA; Patient engagement in care and adherence to medication are critical to achieving the full benefits of antiretroviral therapy (ART) among people with HIV infection. A randomized controlled trial in Kenya, WelTelKenya1, showed that an interactive mobile phone text‐messaging intervention can improve adherence and viral load suppression. We conducted a pilot study to adapt the WelTel intervention for HIV‐infected clients (n = 25) at an HIV clinic in Vancouver, British Columbia. Between April and June 2012, we recruited five participants from five groups: youth (14–24 years), mature (≥50 years), English as a second language, remote (≥3 hours travel time to clinic), and nonsuppressed (CD4+ T cell count <200 cells/mm3 and viral load ≥250 copies/mL on two consecutive occasions). Participants described the intervention as a useful way to communicate with health care providers, thus increasing the ability to access services, report side effects, and attend appointments.

Select Neurocognitive Impairment in HIV-Infected Women: Associations with HIV Viral Load, Hepatitis C Virus, and Depression, but Not Leukocyte Telomere Length

Background Through implementation of combination antiretroviral therapy (cART) remarkable gains have been achieved in the management of HIV infection; nonetheless, the neurocognitive consequences of infection remain a pivotal concern in the cART era. Research has often employed norm-referenced neuropsychological scores, derived from healthy populations (excluding many seronegative individuals at high risk for HIV infection), to characterize impairments in predominately male HIV-infected populations. Methods Using matched-group methodology, we assessed 81 HIV-seropositive (HIV+) women with established neuropsychological measures validated for detection of HIV-related impairments, as well as additional detailed tests of executive function and decision-making from the Cambridge Neuropsychological Test Automated Battery (CANTAB). Results On validated tests, the HIV+ women exhibited impairments that were limited to significantly slower information processing speed when compared with 45 HIV-seronegative (HIV−) women with very similar demographic backgrounds and illness comorbidities. Additionally, select executive impairments in shifting attention (i.e., reversal learning) and in decision-making quality were revealed in HIV+ participants. Modifiers of neurocognition in HIV-infected women included detectable HIV plasma viral load, active hepatitis C virus co-infection, and self-reported depression symptoms. In contrast, leukocyte telomere length (LTL), a marker of cellular aging, did not significantly differ between HIV+ and HIV− women, nor was LTL associated with overall neurocognition in the HIV+ group. Conclusions The findings suggest that well-managed HIV infection may entail a more circumscribed neurocognitive deficit pattern than that reported in many norm-referenced studies, and that common comorbidities make a secondary contribution to HIV-related neurocognitive impairments.