Publications

Metformin is used as a first-line therapy for type 2 diabetes (T2D) and prescribed for numerous other diseases. However, its mechanism of action in the liver has yet to be characterized in a systematic manner. To comprehensively identify genes and regulatory elements associated with metformin treatment, we carried out RNA-seq and ChIP-seq (H3K27ac, H3K27me3) on primary human hepatocytes from the same donor treated with vehicle control, metformin or metformin and compound C, an AMP-activated protein kinase (AMPK) inhibitor (allowing to identify AMPK-independent pathways). We identified thousands of metformin responsive AMPK-dependent and AMPK-independent differentially expressed genes and regulatory elements. We functionally validated several elements for metformin-induced promoter and enhancer activity. These include an enhancer in an ataxia telangiectasia mutated (ATM) intron that has SNPs in linkage disequilibrium with a metformin treatment response GWAS lead SNP (rs11212617) that showed increased enhancer activity for the associated haplotype. Expression quantitative trait locus (eQTL) liver analysis and CRISPR activation suggest that this enhancer could be regulating ATM, which has a known role in AMPK activation, and potentially also EXPH5 and DDX10, its neighboring genes. Using ChIP-seq and siRNA knockdown, we further show that activating transcription factor 3 (ATF3), our top metformin upregulated AMPK-dependent gene, could have an important role in gluconeogenesis repression. Our findings provide a genome-wide representation of metformin hepatic response, highlight important sequences that could be associated with interindividual variability in glycemic response to metformin and identify novel T2D treatment candidates.

OBJECTIVE

To investigate safety of hormonal contraception with regard to thromboembolic events in women with type 1 or 2 diabetes.

RESEARCH DESIGN AND METHODS

We used data from 2002-2011 in Clinformatics Data Mart to identify women in the U.S., 14-44 years of age, with an ICD-9-CM code for diabetes and a prescription for a diabetic medication or device. We examined contraceptive claims and compared time to thromboembolism (venous thrombosis, stroke, or myocardial infarction) among women with diabetes dispensed hormonal contraception using a modification of Cox regression to control for age, smoking, obesity, hypertension, hyperlipidemia, diabetic complications, and history of cancer; we excluded data for 3 months after women gave birth.

RESULTS

We identified 146,080 women with diabetes who experienced 3,012 thromboembolic events. Only 28% of reproductive-aged women with diabetes had any claims for hormonal contraception, with the majority receiving estrogen-containing oral contraceptives. Rates of thromboembolism were highest among women who used the contraceptive patch (16 per 1,000 woman-years) and lowest among women who used intrauterine (3.4 per 1,000 woman-years) and subdermal (0 per 163 woman-years) contraceptives. Compared with use of intrauterine contraception, progestin-only injectable contraception was associated with increased risk of thromboembolism (12.5 per 1,000 woman-years; adjusted hazard ratio 4.69 [95% CI 2.51-8.77]).

CONCLUSIONS

The absolute risk of thromboembolism among women with type 1 or 2 diabetes using hormonal contraception is low. Highly effective, intrauterine and subdermal contraceptives are excellent options for women with diabetes who hope to avoid the teratogenic effects of hyperglycemia by carefully planning their pregnancies.

BACKGROUND

The median age of the single adult homeless population is 50 and rising. Although the prevalence of substance use decreases as individuals age, older adults now have a higher prevalence of substance use than older adults did 10 years ago. Homeless individuals have a higher prevalence of substance use disorders than the general population. However, little is known about substance use in older homeless adults.

METHODS

The objective of the study was to examine prevalence of and factors associated with substance use in a population-based sample (N = 350) of homeless individuals aged 50 and older in Oakland, California. Dependent variables included moderate or greater severity illicit drug symptoms (Alcohol, Smoking, and Substance Involvement Screening Test (ASSIST) score >3) and moderate or greater alcohol symptoms (Alcohol Use Disorders Identification Test (AUDIT) score >7). Independent variables included demographics, mental health problems, and negative life course events such as physical and sexual abuse, school expulsion, and onset of homelessness.

RESULTS

Almost two thirds of participants, 64.6%, had moderate or greater severity symptoms for at least 1 illicit drug; 25.8% had moderate or greater severity alcohol symptoms. History of psychiatric hospitalization was associated with moderate or greater illicit drug symptoms (adjusted odds ratio [AOR] = 1.9, 1.0-3.6). The presence of major depressive symptoms was associated with moderate or greater severity alcohol symptoms (AOR = 1.8, 1.1-3.0).

CONCLUSIONS

In this sample of older homeless adults, substance use is common. There is a need for substance use treatment programs, integrated with mental health services, which are targeted towards the needs of older homeless adults.

For the 2016 end-of-the-year editorial, the PLOS Medicine editors asked 7 global health leaders to discuss developments relevant to the equitable provision of medical care to all populations. The result is a collection of expert views on ethical trial design, research during outbreaks, high-burden infectious diseases, diversity in research and protection of migrants.

OBJECTIVE

Synonymous substitutions K65K/K66K in HIV-1 reverse transcriptase alleviate fitness and fidelity defects in HIV-1 molecular clones harboring thymidine analogue mutations (TAMs); however, their potential for transmission and persistence is unknown. Here, we investigated the temporal appearance of K65K/K66K relative to TAMs in a HIV-1 cohort, their prevalence over time, and their impact on viral fitness in the context of patient-derived reverse transcriptase sequences.

METHODS

Retrospective analyses of the temporal appearance and longitudinal prevalence of synonymous substitutions and drug resistance mutations were performed using the British Columbia Centre for Excellence in HIV/AIDS Drug Treatment Program (DTP) database. Plasma-derived HIV-1 from the DTP was used to generate infectious molecular clones. Growth competition assays were performed to determine viral fitness.

RESULTS

The prevalence of K65K/K66K in drug-naïve individuals tripled from 11% in 1997 to 37% in 2014 (P < 0.0001, n = 5221), with K66K mainly accounting for the increase. These mutations emerged in drug-treated individuals without TAMs in 14% of the cohort and conferred a fitness advantage in the context of patient-derived multidrug-resistant (MDR) virus in the absence of drug.

CONCLUSION

The appearance of K65K/K66K in drug-treated individuals was largely independent of TAMs, suggesting alternative factors are likely associated with their emergence. The increasing K65K/K66K prevalence to over a third of treatment-naïve individuals in the mostly subtype B DTP cohort and their ability to confer a fitness advantage to multidrug-resistant virus might explain the transmission and persistence of virus harbouring K65K/K66K in untreated individuals, and highlights their role in adaptive HIV-1 evolution.