A genetically encoded tool to increase cellular NADH/NAD+ ratio in living cells

Impaired redox metabolism is a key contributor to the etiology of many diseases, including primary mitochondrial disorders, cancer, neurodegeneration and aging. However, mechanistic studies of redox imbalance remain challenging due to limited strategies that can perturb redox metabolism in various cellular or organismal backgrounds. Most studies involving impaired redox metabolism have focused on oxidative stress; consequently, less is known about the settings where there is an overabundance of NADH reducing equivalents, termed reductive stress. Here we introduce a soluble transhydrogenase from Escherichia coli (EcSTH) as a novel genetically encoded tool to promote reductive stress in living cells. When expressed in mammalian cells, EcSTH, and a mitochondrially targeted version (mitoEcSTH), robustly elevated the NADH/NAD+ ratio in a compartment-specific manner. Using this tool, we determined that metabolic and transcriptomic signatures of the NADH reductive stress are cellular background specific. Collectively, our novel genetically encoded tool represents an orthogonal strategy to promote reductive stress.

Complement protein signatures in patients with alcohol-associated hepatitis

Diagnostic challenges continue to impede development of effective therapies for successful management of alcohol-associated hepatitis (AH), thus creating an unmet need to identify and develop non-invasive biomarkers for AH. In murine models of ethanol-induced liver injury, complement activation contributes to hepatic inflammation and injury. Therefore, we hypothesized that complement proteins could be rational diagnostic/prognostic biomarkers in AH. Here, we performed a comparative analysis of data derived from the human hepatic and serum proteome to identify and characterize complement protein signatures in severe AH (sAH). The quantity of multiple complement proteins was perturbed in liver and serum proteome of patients with sAH. Multiple complement proteins differentiated patients with sAH from those with alcohol cirrhosis (AC), alcohol use disorder (AUD) and healthy controls (HCs). Notably, serum collectin 11 and C1q binding protein were strongly associated with sAH and exhibited good discriminatory performance amongst patients with sAH, AC, AUD, and HCs. Furthermore, complement component receptor 1-like protein (CR1L) was negatively associated with pro-inflammatory cytokines. Additionally, lower serum mannose-binding lectin associated serine protease 1 and coagulation factor II were associated with and independently predicted 90-day mortality. In summary, meta-analysis of proteomic profiles from liver and circulation revealed complement protein signatures of sAH, highlighting a complex perturbation of complement and identifying potential diagnostic and prognostic biomarkers for patients with sAH.

ChREBP is activated by reductive stress and mediates GCKR-associated metabolic traits

Common genetic variants in glucokinase regulator (GCKR), which encodes GKRP, a regulator of hepatic glucokinase (GCK), influence multiple metabolic traits in genome-wide association studies (GWASs), making GCKR one of the most pleiotropic GWAS loci in the genome. It is unclear why. Prior work has demonstrated that GCKR influences the hepatic cytosolic NADH/NAD+ ratio, also referred to as reductive stress. Here, we demonstrate that reductive stress is sufficient to activate the transcription factor ChREBP and necessary for its activation by the GKRP-GCK interaction, glucose, and ethanol. We show that hepatic reductive stress induces GCKR GWAS traits such as increased hepatic fat, circulating FGF21, and circulating acylglycerol species, which are also influenced by ChREBP. We define the transcriptional signature of hepatic reductive stress and show its upregulation in fatty liver disease and downregulation after bariatric surgery in humans. These findings highlight how a GCKR-reductive stress-ChREBP axis influences multiple human metabolic traits.

Moderate-high intensity exercise associates with reduced incident alcohol-associated liver disease in high-risk patients

BACKGROUND

Therapies to prevent alcohol-associated liver disease (ALD) in high-risk patients are needed.

AIMS

In this retrospective association study, we examined whether patients with alcohol use disorder (AUD) who reported greater exercise were less likely to develop liver disease.

METHODS

In this retrospective cohort study, we used the Mass General Brigham Biobank to investigate the impact of both moderate-high and light-intensity exercise on the development of ALD in patients with AUD, using clinician-provided diagnostic International Classification of Diseases 10 codes. Exercise was evaluated using a questionnaire completed after an AUD diagnosis, and before evidence of liver disease. Cox regressions were used to generate hazard ratios (HRs) for the development of ALD.

RESULTS

1987 patients met inclusion criteria. These patients were followed for an average of 10.7 years. In multivariable analyses, we found that patients that reported at least 2.5 h of moderate-high intensity exercise/week (confidence interval recommendation for exercise) were less likely to develop ALD compared to patients that did not exercise (HR: 0.26, 95%CI: 0.085-0.64, P = 0.007). Indeed, each hour of moderate-high intensity exercise was associated with progressively decreasing odds of developing ALD (HR: 0.76, 95%CI: 0.58-0.91, P = 0.02). Conversely, patients who did not engage in any moderate-high intensity exercise were more likely to develop ALD (HR: 2.76, 95%CI: 1.44-5.40, P = 0.003).

CONCLUSIONS

In our cohort, patients with AUD who reported moderate-high intensity exercise showed a lower association with incidence of ALD development than patients who did not exercise.

Serum Fibroblast Growth Factor-21 Discriminates Between Decompensated Alcohol-Associated Cirrhosis and Severe Alcohol-Associated Hepatitis

INTRODUCTION

We hypothesized that fibroblast growth factor-21 (FGF-21) would be highly expressed in patients with alcohol-associated hepatitis (AH) and could be a novel and biologically relevant predictive biomarker to reliably distinguish severe AH and decompensated alcohol-associated cirrhosis (AC).

METHODS

We identified a discovery cohort of 88 subjects with alcohol-associated liver disease (ALD) of varying disease severity from our ALD repository. Our validation cohort consisted of 37 patients with a biopsy-proven diagnosis of AH, AC, or absence of ALD with Model for End-Stage Liver Disease scores ≥10. Serum from both groups during index hospitalization was assayed for FGF-21 by ELISA. We performed receiver operating characteristic analysis and prediction modeling in both cohorts to discriminate between AH and AC in high Model for End-Stage Liver Disease (≥20) patients.

RESULTS

In both cohorts, FGF-21 concentrations were highest in subjects with moderate to severe AH compared with those having alcohol use disorder or AC (mean: 2,609 pg/mL, P < 0.0001). The discovery cohort area under the curve of FGF-21 between AH and AC was 0.81 (95% confidence interval: 0.65-0.98, P < 0.01). In the validation cohort, FGF-21 levels were higher in severe AH compared with AC (3,052 vs 1,235 pg/mL, P = 0.03), and the area under the curve was 0.76 (95% confidence interval: 0.56-0.96, P < 0.03). A survival analysis showed that patients with FGF-21 serum levels in the second interquartile had the highest survival compared with all other quartiles.

DISCUSSION

FGF-21 performs well as a predictive biomarker to distinguish severe AH from AC and may be helpful in the management and clinical investigation of patients with severe alcohol-associated liver diseases.

Integrated hepatology and addiction care for inpatients with alcohol use disorder improves outcomes: a prospective study

BACKGROUND

Growing literature highlights the need to integrate hepatology and addiction care to improve outcomes for patients with alcohol use disorder and alcohol-associated liver disease. However, prospective data for this approach are lacking.

METHODS

We prospectively examined the efficacy of an integrated hepatology and addiction medicine approach on alcohol use and hepatology outcomes in inpatients with alcohol use disorder.

FINDINGS

An integrated approach improved the uptake of medical alcohol therapy, hepatic fibrosis screening, and viral hepatitis vaccination compared with a historical control of patients who received addiction medicine care alone. There were no differences in the rates of early alcohol remission. The integration of hepatology and addiction care may improve outcomes in patients with alcohol use disorder.

Salvage of ribose from uridine or RNA supports glycolysis in nutrient-limited conditions

Glucose is vital for life, serving as both a source of energy and carbon building block for growth. When glucose is limiting, alternative nutrients must be harnessed. To identify mechanisms by which cells can tolerate complete loss of glucose, we performed nutrient-sensitized genome-wide genetic screens and a PRISM growth assay across 482 cancer cell lines. We report that catabolism of uridine from the medium enables the growth of cells in the complete absence of glucose. While previous studies have shown that uridine can be salvaged to support pyrimidine synthesis in the setting of mitochondrial oxidative phosphorylation deficiency1, our work demonstrates that the ribose moiety of uridine or RNA can be salvaged to fulfil energy requirements via a pathway based on: (1) the phosphorylytic cleavage of uridine by uridine phosphorylase UPP1/UPP2 into uracil and ribose-1-phosphate (R1P), (2) the conversion of uridine-derived R1P into fructose-6-P and glyceraldehyde-3-P by the non-oxidative branch of the pentose phosphate pathway and (3) their glycolytic utilization to fuel ATP production, biosynthesis and gluconeogenesis. Capacity for glycolysis from uridine-derived ribose appears widespread, and we confirm its activity in cancer lineages, primary macrophages and mice in vivo. An interesting property of this pathway is that R1P enters downstream of the initial, highly regulated steps of glucose transport and upper glycolysis. We anticipate that 'uridine bypass' of upper glycolysis could be important in the context of disease and even exploited for therapeutic purposes.

Psychotherapy for Alcohol Use Disorder Is Associated With Reduced Risk of Incident Alcohol-Associated Liver Disease

BACKGROUND & AIMS

Alcohol-associated liver disease (ALD) is a devastating complication of alcohol use disorder (AUD). Once it develops, ALD is exceedingly difficult to treat; it therefore is critical to identify ways to prevent ALD. By treating the causes of increased alcohol consumption, psychotherapy may offer prophylactic benefit against the development of ALD for patients with AUD.

METHODS

In this retrospective cohort study, we used International Classification of Diseases, 9th and 10th revision, codes to identify 9635 patients with AUD in the Mass General Brigham Biobank. The mean follow-up period from AUD diagnosis was 9.2 years. We used Cox regression models to generate hazard ratios (HR) for the development of ALD given the receipt or nonreceipt of psychotherapy, adjusting for a range of other contributors including the receipt of medication-assisted treatment.

RESULTS

In our cohort, 60.4% of patients were male, 83.5% of patients were white, the median age was 57.0 years, and 3544 patients (36.8%) received psychotherapy. ALD developed in 1135 patients (11.8%). In multivariable analysis, psychotherapy was associated with a reduced rate of ALD (HR, 0.59; 95% CI, 0.50-0.71; P < .001). This association held for both individual psychotherapy (HR, 0.70; 95% CI, 0.56-0.86; P < .001) and group psychotherapy (HR, 0.76; 95% CI, 0.61-0.94; P = .01). Among patients with cirrhosis, psychotherapy was associated with a lower rate of hepatic decompensation (HR, 0.68; 95% CI, 0.44-0.95; P = .03).

CONCLUSIONS

The receipt of psychotherapy in the setting of AUD is associated with reduced incidence and progression of ALD. Given the safety and potential benefit of psychotherapy, clinicians should consider using it to prevent the development of ALD.

The circulating proteomic signature of alcohol-associated liver disease

Despite being a leading cause of advanced liver disease, alcohol-associated liver disease (ALD) has no effective medical therapies. The circulating proteome, which comprises proteins secreted by different cells and tissues in the context of normal physiological function or in the setting of disease and illness, represents an attractive target for uncovering novel biology related to the pathogenesis of ALD. In this work, we used the aptamer-based SomaScan proteomics platform to quantify the relative concentration of over 1300 proteins in a well-characterized cohort of patients with the spectrum of ALD. We found a distinct circulating proteomic signature that correlated with ALD severity, including over 600 proteins that differed significantly between ALD stages, many of which have not previously been associated with ALD to our knowledge. Notably, certain proteins that were markedly dysregulated in patients with alcohol-associated hepatitis were also altered, to a lesser degree, in patients with subclinical ALD and may represent early biomarkers for disease progression. Taken together, our work highlights the vast and distinct changes in the circulating proteome across the wide spectrum of ALD, identifies potentially novel biomarkers and therapeutic targets, and provides a proteomic resource atlas for ALD researchers and clinicians.

Incidence and Progression of Alcohol-Associated Liver Disease After Medical Therapy for Alcohol Use Disorder

IMPORTANCE

Alcohol-associated liver disease (ALD) is one of the most devastating complications of alcohol use disorder (AUD), an increasingly prevalent condition. Medical addiction therapy for AUD may play a role in protecting against the development and progression of ALD.

OBJECTIVE

To ascertain whether medical addiction therapy was associated with an altered risk of developing ALD in patients with AUD.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study used the Mass General Brigham Biobank, an ongoing research initiative that had recruited 127 480 patients between its start in 2010 and August 17, 2021, when data for the present study were retrieved. The mean follow-up duration from AUD diagnosis was 9.2 years. International Statistical Classification of Diseases and Related Health Problems, Tenth Revision diagnosis codes were used to identify ALD and AUD diagnoses.

EXPOSURES

Medical addiction therapy was defined as the documented use of disulfiram, acamprosate, naltrexone, gabapentin, topiramate, or baclofen. Patients were considered to be treated if they initiated medical addiction therapy before the relevant outcome.

MAIN OUTCOMES AND MEASURES

Adjusted odds ratios (aORs) for the development of ALD and hepatic decompensation were calculated and adjusted for multiple risk factors.

RESULTS

The cohort comprised 9635 patients with AUD, of whom 5821 were male individuals (60.4%), and the mean (SD) age was 54.8 (16.5) years. A total of 1135 patients (11.8%) had ALD and 3906 patients (40.5%) were treated with medical addiction therapy. In multivariable analyses, medical addiction therapy for AUD was associated with decreased incidence of ALD (aOR, 0.37; 95% CI, 0.31-0.43; P < .001). This association was evident for naltrexone (aOR, 0.67; 95% CI, 0.46-0.95; P = .03), gabapentin (aOR, 0.36; 95% CI, 0.30-0.43; P < .001), topiramate (aOR, 0.47; 95% CI, 0.32-0.66; P < .001), and baclofen (aOR, 0.57; 95% CI, 0.36-0.88; P = .01). In addition, pharmacotherapy for AUD was associated with lower incidence of hepatic decompensation in patients with cirrhosis (aOR, 0.35; 95% CI, 0.23-0.53, P < .001), including naltrexone (aOR, 0.27; 95% CI, 0.10-0.64; P = .005) and gabapentin (aOR, 0.36; 95% CI, 0.23-0.56; P < .001). This association persisted even when medical addiction therapy was initiated only after the diagnosis of cirrhosis (aOR, 0.41; 95% CI, 0.23-0.71; P = .002).

CONCLUSIONS AND RELEVANCE

Results of this study showed that receipt of medical addiction therapy for AUD was associated with reduced incidence and progression of ALD. The associations of individual pharmacotherapy with the outcomes of ALD and hepatic decompensation varied widely.

Substance use disorder is associated with alcohol-associated liver disease in patients with alcohol use disorder

BACKGROUND AND AIMS

Substance use disorder (SUD) commonly associates with alcohol use disorder (AUD), and certain substances have independently been shown to drive liver injury. In this work, we sought to determine if co-existing SUD in patients with AUD associated with the presence of alcohol-associated liver disease (ALD).

METHODS

We performed a cross-sectional analysis using the Mass General Brigham Biobank to identify patients based on ICD-10 codes. We performed multivariate analyses accounting for a wide range of demographic and clinical variables to evaluate the association between SUD and ALD. We subsequently used the same method to evaluate the association between SUD and hepatic decompensation.

RESULTS

We identified 2848 patients with a diagnosis of AUD, 9.0% of which had ALD. 25.2% had a history of SUD. In multivariate analyses, patients with SUD were more frequently diagnosed with ALD compared to those without SUD (OR = 1.95, P = 0.001). Furthermore, the number of concurrent SUDs was positively associated with the diagnosis of ALD (OR: 1.33, P < 0.001). Independent of the presence of other SUDs, opioid use disorder in patients with AUD was associated with ALD (OR = 1.902, P = 0.02). In subsequent analyses, we found that sedative use disorder was associated with hepatic decompensation (OR: 2.068, P = 0.03).

CONCLUSIONS

In patients with AUD, SUD, and in particular opioid use disorder, was independently associated with the diagnosis of ALD.

MitoCarta3.0: an updated mitochondrial proteome now with sub-organelle localization and pathway annotations

The mammalian mitochondrial proteome is under dual genomic control, with 99% of proteins encoded by the nuclear genome and 13 originating from the mitochondrial DNA (mtDNA). We previously developed MitoCarta, a catalogue of over 1000 genes encoding the mammalian mitochondrial proteome. This catalogue was compiled using a Bayesian integration of multiple sequence features and experimental datasets, notably protein mass spectrometry of mitochondria isolated from fourteen murine tissues. Here, we introduce MitoCarta3.0. Beginning with the MitoCarta2.0 inventory, we performed manual review to remove 100 genes and introduce 78 additional genes, arriving at an updated inventory of 1136 human genes. We now include manually curated annotations of sub-mitochondrial localization (matrix, inner membrane, intermembrane space, outer membrane) as well as assignment to 149 hierarchical 'MitoPathways' spanning seven broad functional categories relevant to mitochondria. MitoCarta3.0, including sub-mitochondrial localization and MitoPathway annotations, is freely available at http://www.broadinstitute.org/mitocarta and should serve as a continued community resource for mitochondrial biology and medicine.

Hepatic NADH reductive stress underlies common variation in metabolic traits

The cellular NADH/NAD+ ratio is fundamental to biochemistry, but the extent to which it reflects versus drives metabolic physiology in vivo is poorly understood. Here we report the in vivo application of Lactobacillus brevis (Lb)NOX1, a bacterial water-forming NADH oxidase, to assess the metabolic consequences of directly lowering the hepatic cytosolic NADH/NAD+ ratio in mice. By combining this genetic tool with metabolomics, we identify circulating α-hydroxybutyrate levels as a robust marker of an elevated hepatic cytosolic NADH/NAD+ ratio, also known as reductive stress. In humans, elevations in circulating α-hydroxybutyrate levels have previously been associated with impaired glucose tolerance2, insulin resistance3 and mitochondrial disease4, and are associated with a common genetic variant in GCKR5, which has previously been associated with many seemingly disparate metabolic traits. Using LbNOX, we demonstrate that NADH reductive stress mediates the effects of GCKR variation on many metabolic traits, including circulating triglyceride levels, glucose tolerance and FGF21 levels. Our work identifies an elevated hepatic NADH/NAD+ ratio as a latent metabolic parameter that is shaped by human genetic variation and contributes causally to key metabolic traits and diseases. Moreover, it underscores the utility of genetic tools such as LbNOX to empower studies of 'causal metabolism'.

Hepatic connexin 32 associates with nonalcoholic fatty liver disease severity

Emerging data highlight the critical role for the innate immune system in the progression of nonalcoholic fatty liver disease (NAFLD). Connexin 32 (Cx32), the primary liver gap junction protein, is capable of modulating hepatic innate immune responses and has been studied in dietary animal models of steatohepatitis. In this work, we sought to determine the association of hepatic Cx32 with the stages of human NAFLD in a histologically characterized cohort of 362 patients with NAFLD. We also studied the hepatic expression of the genes and proteins known to interact with Cx32 (known as the connexome) in patients with NAFLD. Last, we used three independent dietary mouse models of nonalcoholic steatohepatitis to investigate the role of Cx32 in the development of steatohepatitis and fibrosis. In a univariate analysis, we found that Cx32 hepatic expression associates with each component of the NAFLD activity score and fibrosis severity. Multivariate analysis revealed that Cx32 expression most closely associated with the NAFLD activity score and fibrosis compared to known risk factors for the disease. Furthermore, by analyzing the connexome, we identified novel genes related to Cx32 that associate with NAFLD progression. Finally, we demonstrated that Cx32 deficiency protects against liver injury, inflammation, and fibrosis in three murine models of nonalcoholic steatohepatitis by limiting initial diet-induced hepatoxicity and subsequent increases in intestinal permeability. Conclusion: Hepatic expression of Cx32 strongly associates with steatohepatitis and fibrosis in patients with NAFLD. We also identify novel genes associated with NAFLD and suggest that Cx32 plays a role in promoting NAFLD development. (Hepatology Communications 2018;2:786-797).

Spatiotemporal compartmentalization of hepatic NADH and NADPH metabolism

Compartmentalization is a fundamental design principle of eukaryotic metabolism. Here, we review the compartmentalization of NAD+/NADH and NADP+/NADPH with a focus on the liver, an organ that experiences the extremes of biochemical physiology each day. Historical studies of the liver, using classical biochemical fractionation and measurements of redox-coupled metabolites, have given rise to the prevailing view that mitochondrial NAD(H) pools tend to be oxidized and important for energy homeostasis, whereas cytosolic NADP(H) pools tend to be highly reduced for reductive biosynthesis. Despite this textbook view, many questions still remain as to the relative size of these subcellular pools and their redox ratios in different physiological states, and to what extent such redox ratios are simply indicators versus drivers of metabolism. By performing a bioinformatic survey, we find that the liver expresses 352 known or predicted enzymes composing the hepatic NAD(P)ome, i.e. the union of all predicted enzymes producing or consuming NADP(H) or NAD(H) or using them as a redox co-factor. Notably, less than half are predicted to be localized within the cytosol or mitochondria, and a very large fraction of these genes exhibit gene expression patterns that vary during the time of day or in response to fasting or feeding. A future challenge lies in applying emerging new genetic tools to measure and manipulate in vivo hepatic NADP(H) and NAD(H) with subcellular and temporal resolution. Insights from such fundamental studies will be crucial in deciphering the pathogenesis of very common diseases known to involve alterations in hepatic NAD(P)H, such as diabetes and fatty liver disease.

Clinical Genetic Testing in Gastroenterology

Rapid advances in genetics have led to an increased understanding of the genetic determinants of human disease, including many gastrointestinal (GI) disorders. Coupled with a proliferation of genetic testing services, this has resulted in a clinical landscape where commercially available genetic tests for GI disorders are now widely available. In this review, we discuss the current status of clinical genetic testing for GI illnesses, review the available testing options, and briefly discuss indications for and practical aspects of such testing. Our goal is to familiarize the practicing gastroenterologist with this rapidly changing and important aspect of clinical care.

Complementation of mitochondrial electron transport chain by manipulation of the NAD+/NADH ratio

A decline in electron transport chain (ETC) activity is associated with many human diseases. Although diminished mitochondrial adenosine triphosphate production is recognized as a source of pathology, the contribution of the associated reduction in the ratio of the amount of oxidized nicotinamide adenine dinucleotide (NAD(+)) to that of its reduced form (NADH) is less clear. We used a water-forming NADH oxidase from Lactobacillus brevis (LbNOX) as a genetic tool for inducing a compartment-specific increase of the NAD(+)/NADH ratio in human cells. We used LbNOX to demonstrate the dependence of key metabolic fluxes, gluconeogenesis, and signaling on the cytosolic or mitochondrial NAD(+)/NADH ratios. Expression of LbNOX in the cytosol or mitochondria ameliorated proliferative and metabolic defects caused by an impaired ETC. The results underscore the role of reductive stress in mitochondrial pathogenesis and demonstrate the utility of targeted LbNOX for direct, compartment-specific manipulation of redox state.

Endobiont viruses sensed by the human host - beyond conventional antiparasitic therapy

Wide-spread protozoan parasites carry endosymbiotic dsRNA viruses with uncharted implications to the human host. Among them, Trichomonas vaginalis, a parasite adapted to the human genitourinary tract, infects globally ∼250 million each year rendering them more susceptible to devastating pregnancy complications (especially preterm birth), HIV infection and HPV-related cancer. While first-line antibiotic treatment (metronidazole) commonly kills the protozoan pathogen, it fails to improve reproductive outcome. We show that endosymbiotic Trichomonasvirus, highly prevalent in T. vaginalis clinical isolates, is sensed by the human epithelial cells via Toll-like receptor 3, triggering Interferon Regulating Factor -3, interferon type I and proinflammatory cascades previously implicated in preterm birth and HIV-1 susceptibility. Metronidazole treatment amplified these proinflammatory responses. Thus, a new paradigm targeting the protozoan viruses along with the protozoan host may prevent trichomoniasis-attributable inflammatory sequelae.

A facile method for reversibly linking a recombinant protein to DNA

We present a facile method for linking recombinant proteins to DNA. It is based on the nickel-mediated interaction between a hexahistidine tag (His(6)-tag) and DNA functionalized with three nitrilotriacetic acid (NTA) groups. The resulting DNA-protein linkage is site-specific. It can be broken quickly and controllably by the addition of a chelating agent that binds nickel. We have used this new linker to bind proteins to a variety of DNA motifs commonly used in the fabrication of nanostructures by DNA self-assembly.

High-resolution structural analysis of a DNA nanostructure by cryoEM

Many DNA nanostructures have been produced and a wide range of potential applications have been proposed. However, confirmation of accurate 3D construction is particularly challenging. Here, we demonstrate that cryoEM may be exploited to obtain structural information at sufficient resolution to visualize the DNA helix and reveal the absolute stereochemistry of a 7 nm self-assembled DNA tetrahedron. Structural analysis at such high resolution by cryoEM image analysis is unprecedented for any biological molecule of this size.

Reconfigurable, braced, three-dimensional DNA nanostructures

DNA nanotechnology makes use of the exquisite self-recognition of DNA in order to build on a molecular scale. Although static structures may find applications in structural biology and computer science, many applications in nanomedicine and nanorobotics require the additional capacity for controlled three-dimensional movement. DNA architectures can span three dimensions and DNA devices are capable of movement, but active control of well-defined three-dimensional structures has not been achieved. We demonstrate the operation of reconfigurable DNA tetrahedra whose shapes change precisely and reversibly in response to specific molecular signals. Shape changes are confirmed by gel electrophoresis and by bulk and single-molecule Förster resonance energy transfer measurements. DNA tetrahedra are natural building blocks for three-dimensional construction; they may be synthesized rapidly with high yield of a single stereoisomer, and their triangulated architecture conveys structural stability. The introduction of shape-changing structural modules opens new avenues for the manipulation of matter on the nanometre scale.

Rapid chiral assembly of rigid DNA building blocks for molecular nanofabrication

Practical components for three-dimensional molecular nanofabrication must be simple to produce, stereopure, rigid, and adaptable. We report a family of DNA tetrahedra, less than 10 nanometers on a side, that can self-assemble in seconds with near-quantitative yield of one diastereomer. They can be connected by programmable DNA linkers. Their triangulated architecture confers structural stability; by compressing a DNA tetrahedron with an atomic force microscope, we have measured the axial compressibility of DNA and observed the buckling of the double helix under high loads.

A vaccine to prevent herpes zoster and postherpetic neuralgia in older adults

BACKGROUND

The incidence and severity of herpes zoster and postherpetic neuralgia increase with age in association with a progressive decline in cell-mediated immunity to varicella-zoster virus (VZV). We tested the hypothesis that vaccination against VZV would decrease the incidence, severity, or both of herpes zoster and postherpetic neuralgia among older adults.

METHODS

We enrolled 38,546 adults 60 years of age or older in a randomized, double-blind, placebo-controlled trial of an investigational live attenuated Oka/Merck VZV vaccine ("zoster vaccine"). Herpes zoster was diagnosed according to clinical and laboratory criteria. The pain and discomfort associated with herpes zoster were measured repeatedly for six months. The primary end point was the burden of illness due to herpes zoster, a measure affected by the incidence, severity, and duration of the associated pain and discomfort. The secondary end point was the incidence of postherpetic neuralgia.

RESULTS

More than 95 percent of the subjects continued in the study to its completion, with a median of 3.12 years of surveillance for herpes zoster. A total of 957 confirmed cases of herpes zoster (315 among vaccine recipients and 642 among placebo recipients) and 107 cases of postherpetic neuralgia (27 among vaccine recipients and 80 among placebo recipients) were included in the efficacy analysis. The use of the zoster vaccine reduced the burden of illness due to herpes zoster by 61.1 percent (P<0.001), reduced the incidence of postherpetic neuralgia by 66.5 percent (P<0.001), and reduced the incidence of herpes zoster by 51.3 percent (P<0.001). Reactions at the injection site were more frequent among vaccine recipients but were generally mild.

CONCLUSIONS

The zoster vaccine markedly reduced morbidity from herpes zoster and postherpetic neuralgia among older adults.

The single-step synthesis of a DNA tetrahedron

A tetrahedral nanostructure whose edges are DNA double helices self-assembles spontaneously when four appropriately designed oligonucleotides are annealed together in solution; the ease of synthesis, rigidity, and adaptability of this construct make it a promising candidate as a cage for other large molecules and as a building block for more complicated nanostructures.

Nasal carriage of and infection with Staphylococcus aureus in HIV-infected patients

BACKGROUND

Staphylococcus aureus is a common cause of serious infection in patients infected with HIV.

OBJECTIVES

To evaluate risk factors for and quantitative effect of S. aureus infection in HIV-infected patients, with special attention to nasal carriage.

DESIGN

Prospective, multihospital cohort study.

SETTING

Three tertiary care Veterans Affairs Medical Centers.

PARTICIPANTS

231 ambulatory HIV-infected patients.

RESULTS

Thirty-four percent of patients were nasal carriers of S. aureus. Of these patients, 38% were persistent carriers and 62% were intermittent carriers. Twenty-one episodes of infection occurred in 13 patients: Ten were bacteremias (including 2 cases of endocarditis), 1 was pneumonia, and 10 were cutaneous or subcutaneous infections. Seventeen (85%) of these episodes occurred in patients with CD4 counts less than 100 cells/mm3. Recurrent infections occurred in 3 of 7 patients who survived an initial S. aureus infection. The mortality rate was higher among patients with S. aureus infection than among those without infection (P = 0.03). Factors significantly associated with S. aureus infection were nasal carriage, presence of a vascular catheter, low CD4 count, and neutropenia. Molecular strain typing indicated that for 6 of 7 infected patients, the strain of S. aureus isolated from the infected sites was the same as that previously cultured from the nares.

CONCLUSION

Nasal carriage is an important risk factor for S. aureus infection in HIV-infected patients. Controlled studies are indicated to determine whether eradication of nasal carriage in a selected subset of patients (for example, those with a low CD4 cell count) might prevent invasive S. aureus infection in patients with HIV infection.

Renin profile, race, and antihypertensive efficacy with atenolol and labetalol

In this randomised double-blind parallel study, we compared the efficacy of labetalol and atenolol in a group of black (n = 33) and white (n = 34) hypertensives with uncomplicated essential hypertension after obtaining pretreatment renin profiles. After single-blind placebo (14-21 days), patients with standing diastolic BP between 105-119 mmHg were randomised to receive either labetalol (100-800 mg twice daily) or atenolol (50-100 mg once daily) to achieve a DBP less than 90 mmHg. Dosage titration occurred at weekly intervals for labetalol and biweekly for atenolol. The supine BP decrease with atenolol was -18/-14 vs. -6/-6 mmHg in whites vs. blacks respectively. With labetalol, it was -13/-12 in whites and -2/-7 mmHg in blacks. Standing BPs were: -19/-14 vs. -4/-5, whites vs. blacks with atenolol and -17/-17 vs. -19/-9 mmHg with labetalol. Neither labetalol nor atenolol was as effective in black compared with white hypertensives. The atenolol but not labetalol BP response was positively correlated with pretreatment renin values.

The effects of benazepril, a new angiotensin-converting enzyme inhibitor, in mild to moderate essential hypertension: a multicenter study

Benazepril hydrochloride is a new angiotensin-converting enzyme inhibitor. In a multicenter study, 206 patients with mild to moderate hypertension were randomized to receive benazepril at a dose of 2, 5, 10, or 20 mg, hydrochlorothiazide, 25 mg, or placebo once daily for 4 weeks. The 20 mg dosage of benazepril lowered blood pressure to a degree equal to that of 25 mg hydrochlorothiazide: -12.2/7.7 mm Hg and -13.4/-7.5 mm Hg, respectively. Hydrochlorothiazide proved to be more effective in black subjects. At lower dosage levels of benazepril (2, 5, and 10 mg), blood pressure reduction was not significantly different from that with placebo. In those patients who failed to achieve goal diastolic blood pressure of less than 90 mm Hg with monotherapy after 4 weeks, the addition of open-label hydrochlorothiazide (25 mg/day) to benazepril, hydrochlorothiazide, or placebo produced a substantial additional decrease in blood pressure over a 2-week period. No definite adverse effects on hematologic measurements, serum biochemistry test results, or urinalyses were noted. Subjective adverse experiences were common in all groups but except in three or possibly four instances were not considered causally related to the study drug.

The effect of phenylpropanolamine on 24-hour blood pressure in normotensive subjects administered indomethacin

We evaluated the effect of phenylpropanolamine hydrochloride (PPA) in 14 young, healthy, normotensive women who concurrently received indomethacin. Subjects received sustained-release (SR) indomethacin 75 mg bid and were randomly assigned to receive double-blind SR PPA 75 mg/d or placebo for four days. After a six-day washout period, subjects were crossed over to the opposite four-day double-blind treatment. Following an additional six-day washout period, subjects received indomethacin placebo and PPA placebo during a final, single-blind four-day period. Twenty-four-hour blood pressure (BP) monitoring every 30 minutes and a 24-hour urine collection for prostaglandin E2 (PGE2) were performed on the fourth day of each treatment period. Compliance with the medication regimen was confirmed by drug concentrations, pill counts, and urinary PGE2 concentrations. Compared with the indomethacin and placebo treatment periods, the combination of indomethacin and PPA had no significant effect on mean systolic or diastolic BP during the 24-hour study period or during any four-hour interval. We conclude that the combination of SR PPA 75 mg/d and SR indomethacin 150 mg/d for four days has no adverse effect on BP in normotensive women.

Isradipine (PN 200-110) versus hydrochlorothiazide in mild to moderate hypertension. A multicenter study

The effects of 10 weeks of treatment with isradipine (ISRP), a new dihydropyridine Ca antagonist, was evaluated in a prospective, randomized, double-blind, parallel group, hydrochlorothiazide (HCTZ) controlled study in patients with mild to moderate hypertension. Of 98 patients enrolled, 73 completed the study and were deemed valid for efficacy analyses; 36 in the ISRP group and 37 in the HCTZ group. Monotherapy with ISRP significantly (P less than 0.001) decreased (mean +/- SD) sitting systolic blood pressure (BP) from 146 +/- 11 mm Hg to 128 +/- 11 mm Hg and diastolic BP from 100 +/- 4 mm Hg to 83 +/- 5 mm Hg. Heart rate during the plateau period was not significantly different (76 +/- 11 vs 78 +/- 11 bpm) between the ISRP and HCTZ groups. These reductions in BP were comparable to monotherapy with HCTZ. The mean reduction in diastolic BP with ISRP (17 +/- 6 mm Hg) was significantly (P less than 0.05) greater than that with HCTZ (14 +/- 5 mm Hg). The mean doses for ISRP and HCTZ were 12 mg/day and 60 mg/day, respectively. There was no significant difference in frequency of common side effects (headache, nausea, fatigue, dizziness, palpitations) between the two groups. However, transient or intermittent peripheral edema occurred more frequently in ISRP group. Four patients in ISRP group (two due to edema and two due to palpitations) and two patients in HCTZ group (due to poor BP control) were discontinued from the study. Our results indicate that ISRP in doses of 5 to 10 mg bid is as effective as HCTZ as monotherapy in the treatment of mild to moderate hypertension.

Effect of high-dose ibuprofen on 24-hour blood pressure in healthy women

The nonsteroidal antiinflammatory drug (NSAID) indomethacin has been shown to increase blood pressure in normotensive individuals. The effect of other NSAID on blood pressure has not been as well studied. We evaluated the effects of ibuprofen, an NSAID currently available without a prescription, on 24-hour ambulatory blood pressure in ten young, healthy, normotensive women. Using a randomized, crossover, double-blind design, subjects received ibuprofen 800 mg and a placebo identical in appearance to ibuprofen three times a day for eight days with a washout period between regimens. Subjects were instructed to follow a no-added salt diet during the study. Twenty-four-hour blood pressure monitoring and 24-hour urine collection for prostaglandin E2, creatinine, and sodium were performed on days 1 and 8 of each study week. Tablet counts and a 40 percent reduction in urinary prostaglandin E2 documented compliance with ibuprofen. Ibuprofen had no significant effect on systolic or diastolic blood pressure at any hour during the 24-hour period. Mean blood pressure for the 24-hour period was 112/73 and 111/73 mm Hg on day 1 and 111/73 and 112/73 mm Hg on day 8 for placebo and ibuprofen, respectively. We conclude that ibuprofen at doses as high as 2400 mg/d for up to seven days has no effect on blood pressure in normotensive women. Further studies are needed in hypertensive subjects.

The effect of phenylpropanolamine on ambulatory blood pressure

Phenylpropanolamine (PPA) is a sympathomimetic amine and component of many over-the-counter decongestants and anorectic agents. It has been reported to cause elevated blood pressure and even hypertensive crises. The pressor effects with therapeutic doses are not well established. We monitored the effects of acute and chronic PPA dosing using 24-hour ambulatory blood pressure recording as a sensitive method of monitoring blood pressure variability. Eighteen normotensive male subjects were randomly assigned to receive 75 mg PPA (sustained-release preparation) or placebo in a double-blind crossover design with blood pressure monitored on days 1 (D1) and 6 (D6) of each period. There was no significant difference in blood pressure when compared as either 2-hour intervals or 24-hour global means: (placebo) 116/68 (D1), 117/68 (D6); (PPA) 118/69 (D1), 119/69 (D6). Our results document the absence of pressor effect with PPA in therapeutic doses even with repeated measurements and further confirm the reproducibility of 24-hour blood pressure monitoring.

The effect of low-dose hydrochlorothiazide on blood pressure, serum potassium, and lipoproteins

Recent clinical trials in hypertension suggest that thiazide diuretics may increase coronary heart deaths in selected patients, possibly through adverse effects on serum potassium, lipids, lipoproteins, and/or apolipoproteins. Administration of smaller doses of diuretics has been recommended to decrease this risk. We evaluated 12.5-mg and 112.5-mg daily doses of hydrochlorothiazide (HCTZ) administered for 1 month to nine postmenopausal black female hypertensives using a double-blind, randomized, crossover design. Both regimens produced significant reductions in sitting diastolic blood pressure, a mean of 11 mm Hg with the high dose and 8 mm Hg with the low dose. The high dose produced a mean 0.7 mEq/L reduction in serum potassium while the low dose caused no change. Both doses produced similar changes in serum lipoproteins. Statistically significant elevations were seen in total cholesterol (approximately 12%), LDL cholesterol (approximately 20%), cholesterol: HDL ratio (approximately 15%), and apolipoprotein B (approximately 20%). Apolipoprotein A1 was significantly reduced (approximately 6%). These results support the use of low doses of HCTZ in mild hypertension to avoid hypokalemia, but suggest that adverse changes in serum lipids will occur.

Labetalol by continuous intravenous infusion in severe hypertension

This study documents our experience with labetalol administered by continuous intravenous infusion for severe hypertension. Infusions were performed in 14 hospitalized patients (15 infusions) with supine diastolic pressure greater than 125 mmHg or supine systolic pressure greater than 200 mmHg. Blood pressures were measured by intra-arterial recording or an Arteriosonde 1225 Doppler instrument standardized with a mercury sphygmomanometer. Patients initially received 2 mg/min continuous infusion; the infusion rate varied between 0.5 and 2.0 mg/min according to the protocol. The infusion was terminated when diastolic pressure decreased 30 mmHg or when 300 mg of the drug had been infused. Goal blood pressure was achieved in all but two infusions. Sedation was the most common adverse reaction, followed by nausea and diaphoresis. No patient required discontinuation or reduction in infusion rate secondary to side effects. We conclude that continuous intravenous infusion of labetalol offers an effective alternative to current parenteral therapy.

Use of antihypertensive agents in patients with glucose intolerance

The selection, use, and potential adverse effects of antihypertensive agents in patients with glucose intolerance are reviewed. Thiazide diuretics frequently impair glucose tolerance, but this deterioration is usually modest and should not preclude use of these agents in most patients with glucose intolerance. The loop diuretics furosemide and ethacrynic acid have also been associated with decreased glucose tolerance. The beta-adrenergic blocking agents may inhibit insulin secretion, but few patients will experience clinically important elevations in blood glucose. Rather than producing glucose intolerance, these agents may delay recovery from hypoglycemic episodes and may mask catecholamine-induced symptoms of hypoglycemia. In certain cases, use of cardioselective beta blockers or avoidance of beta-blocker therapy may be indicated, especially in insulin-dependent diabetics. The calcium-channel blocking agents nifedipine and verapamil have been reported to produce diabetogenic effects in a few studies, but further investigations are needed to define the extent of these effects. Available evidence indicates that sympatholytic agents such as guanethidine and reserpine, alpha 2-adrenergic agonists such as methyldopa and clonidine, the alpha 1-blocking agent prazosin, and the vasodilators captopril and hydralazine produce few, if any, clinically important changes in glucose tolerance. While no antihypertensive agents are absolutely contraindicated in patients with glucose intolerance, patients with glucose intolerance who are receiving thiazide diuretics, beta blockers, and calcium-channel blocking agents should be monitored with extra care for hyperglycemia or deterioration in glucose tolerance.

Inhibition of platelet aggregation and thromboxane production by pinacidil

We examined the effects of pinacidil on in vitro platelet function and arachidonic acid metabolism. Pinacidil is an arterial vasodilator currently undergoing clinical trials. Although its mechanism of action is yet undetermined, there is evidence that the activity of other vasodilators may in part be mediated through their effects on arachidonic acid metabolism. Alterations in platelet function were investigated by measuring ADP-induced aggregation in aliquots of human platelet rich plasma that were preincubated with pinacidil. Changes in arachidonic acid metabolism were determined using washed platelets incubated with 14C labeled arachidonic acid after preincubation with pinacidil or indomethacin. The arachidonate metabolites formed were extracted, separated by thin layer chromatography and quantitated via liquid scintillation spectrometry. Pinacidil inhibited platelet aggregation in a concentration dependent manner with 94% inhibition at 0.005M pinacidil. Pinacidil also caused concentration dependent inhibition of TXB2 production (63% inhibition at 0.01M) with reciprocal increases in PGE2 and PGF2 alpha production. There was no significant alteration in arachidonic acid utilization. Indomethacin (0.01M), as expected, inhibited TXB2 as well as PGE2 and PGF2 alpha synthesis. We conclude that, under the conditions of our assay, pinacidil inhibits platelet aggregation and specifically inhibits thromboxane synthetase, an action different from that of indomethacin. Alterations in the relative synthesis of vasodilating and vasoconstricting prostaglandins may be one mechanism whereby pinacidil exerts its antihypertensive activity.

The effect of ranitidine and cimetidine on single-dose diltiazem pharmacokinetics

The effects of two histamine 2-receptor antagonists, cimetidine and ranitidine, on the single-dose pharmacokinetics of diltiazem were studied in 6 healthy subjects. A single 60-mg oral dose of diltiazem was administered alone, after ranitidine 150 mg twice daily for 7 days, and after cimetidine 300 mg 4 times a day for 7 days. Plasma samples were obtained over a 10-hour period and analyzed for the parent drug and one of its metabolites, deacetyldiltiazem (DAD). Concurrent cimetidine produced a significant (p less than 0.05) increase in diltiazem levels at most time points, in peak concentration and area under the concentration-time curve. These variables were also increased during concurrent ranitidine administration but did not reach statistical significance. The DAD plasma concentration was below measurable levels during the control phase but increased during concurrent cimetidine and ranitidine administration. Caution should be exercised when diltiazem is administered concurrently with cimetidine and possibly, ranitidine.

Endogenous prostacyclin synthesis is decreased during activation of the renin-angiotensin system in man

Prostacyclin has been implicated as a mediator of renin release, whereas angiotensin II evokes prostaglandin I2 (PGI2) release from both vascular and nonvascular tissues in vitro. The physiological significance of these observations was assessed by measurement of an index of endogenous prostacyclin biosynthesis in human volunteers during varied activation of the renin-angiotensin system secondary to manipulation of dietary sodium. Excretion of the major urinary metabolite of prostacyclin in man, 2,3-dinor-6-keto-PGF1 alpha (PGI-M), fell from 295 +/- 51 to 176 +/- 35 (+/- SEM) ng g creatinine-1 (P less than 0.01) in 10 normal subjects when sodium intake was decreased from 150 to 10 meq/day. In five patients with primary hyperaldosteronism, PGI-M fell from 199 +/- 34 ng g creatinine-1 preoperatively to 120 +/- 26 pg/mg creatinine-1 after removal of the adenoma. In such patients, the reduction in PGI-M was associated with a significant increase in PRA. Thus, in both normal subjects and patients with hyperaldosteronism, PGI-M excretion fell rather than increased with activation of the renin-angiotensin system. This suggests that systemic biosynthesis of PGI2 is unrelated to renin release and that angiotensin II is unlikely to stimulate endogenous prostacyclin biosynthesis under these conditions in man.

Assessment of the extent to exogenous prostaglandin I2 is converted to 6-keto-prostaglandin E1 in human subjects

6-Keto-prostaglandin (PG) E1 has been suggested as a possible active metabolite of PGI2. The objective of this study was to evaluate whether 6-keto-PGE1 might mediate the biological responses of exogenous PGI2 in man. Toward this end, a novel gas chromatographic-mass spectrometric assay for 6-keto-PGE1, was developed. Selective ion monitor traces from human plasma detected levels that were at the lower limit of sensitivity for this assay and positive mass spectral identification was not possible. An infusion of PGI2 (8 ng/kg/min) which caused systemic hemodynamic changes did not alter plasma levels of 6-keto-PGE1. We conclude that exogenous PGI2 is not converted to an appreciable extent to 6-keto-PGE1 in man and, therefore, 6-keto-PGE1 biosynthesis is unlikely to be responsible for the biological effects of infused PGI2.

Prostacyclin production during pregnancy: comparison of production during normal pregnancy and pregnancy complicated by hypertension

We investigated prostacyclin (PGI2) biosynthesis during pregnancy by measuring urinary excretion of 2,3-dinor-6-keto-prostaglandin F1 alpha (dinor) and 15-keto-13,14-dihydro-2,3-dinor-6-keto-prostaglandin F1 alpha (15 kd dinor) with the use of specific gas chromatography-mass spectrometry assays. Nine normotensive nonpregnant women, five normotensive women in the mid-trimester of pregnancy, eight normotensive women in the third trimester of pregnancy, and six women who developed hypertension during the third trimester provided 24-hour samples of urine. Normal pregnant women had a fivefold increase in urinary excretion of dinor in comparison to nonpregnant women (253 +/- 21 ng dinor/gm creatinine for controls vs. 1,224 +/- 110 and 1,127 +/- 152 for second and third trimesters) (mean +/- SEM). Pregnant subjects with hypertension had a significant (50%) reduction in urinary dinor excretion in comparison to normotensive pregnant subjects (561 +/- 105 ng dinor/gm creatinine). In subjects selected from each group, the ratio of dinor to 15 kd dinor remained constant. We conclude that PGI2 biosynthesis is increased during normal pregnancy, and that this increase is less in pregnancy-induced hypertension. This raises the possibility that PGI2 helps mediate hemodynamic changes during normal pregnancy, and that a relative decrease in production might be related to the pathogenesis of pregnancy-induced hypertension.