Bradley E. Aouizerat

SIRT3 Deficiency and Mitochondrial Protein Hyperacetylation Accelerate the Development of the Metabolic Syndrome

Acetylation is increasingly recognized as an important metabolic regulatory posttranslational protein modification, yet the metabolic consequence of mitochondrial protein hyperacetylation is unknown. We find that high-fat diet (HFD) feeding induces hepatic mitochondrial protein hyperacetylation in mice and downregulation of the major mitochondrial protein deacetylase SIRT3. Mice lacking SIRT3 (SIRT3KO) placed on a HFD show accelerated obesity, insulin resistance, hyperlipidemia, and steatohepatitis compared to wild-type (WT) mice. The lipogenic enzyme stearoyl-CoA desaturase 1 is highly induced in SIRT3KO mice, and its deletion rescues both WT and SIRT3KO mice from HFD-induced hepatic steatosis and insulin resistance. We further identify a single nucleotide polymorphism in the human SIRT3 gene that is suggestive of a genetic association with the metabolic syndrome. This polymorphism encodes a point mutation in the SIRT3 protein, which reduces its overall enzymatic efficiency. Our findings show that loss of SIRT3 and dysregulation of mitochondrial protein acetylation contribute to the metabolic syndrome.

Correlation of paired liver biopsies in morbidly obese patients with suspected nonalcoholic fatty liver disease

In the absence of surrogate markers, the evaluation of suspected nonalcoholic fatty liver disease (NAFLD) is highly dependent on histological examination. The extent of sampling variability affecting the reliability of a single liver biopsy in patients with suspected NAFLD is poorly characterized. This prospective study aimed to correlate precise histological findings in paired biopsies—right and left lobe—in the diagnosis of NAFLD in morbidly obese subjects undergoing bariatric surgery employing both Brunt and Matteoni classifications and the NAFLD Activity Score (NAS). We also aimed to determine whether the composite histopathological findings of the two biopsies would improve diagnostic accuracy. Consecutive subjects had an intraoperative biopsy from both right and left lobes, evaluated and scored in a blinded manner. Intraobserver agreement was also assessed. Kappa coefficients of agreement were calculated. Forty‐one subjects had acceptable biopsies. Agreement for steatosis was excellent and moderate for fibrosis. Concordance was only fair for most features of necroinflammation. Intraobserver agreement was only moderate for lobular inflammation. Excellent agreement was seen for the diagnosis of NASH using Brunt criteria and good agreement when using Matteoni and NAS scoring systems. Composite biopsy data particularly improved identification of hepatocyte ballooning. The diagnostic accuracy also improved substantially when composite features were compared with single‐sided biopsy features, especially for the Matteoni and NAS scoring systems. In conclusion, significant sampling variability occurs in NAFLD, particularly for features of necroinflammation. This should be factored into the design of clinical trials and studies of the natural history of the disease. (HEPATOLOGY 2006;44:874–880.)

Subgroups of Patients With Cancer With Different Symptom Experiences and Quality-of-Life Outcomes: A Cluster Analysis

PURPOSE/OBJECTIVES To identify subgroups of outpatients with cancer based on their experiences with the symptoms of fatigue, sleep disturbance, depression, and pain; to explore whether patients in the subgroups differed on selected demographic, disease, and treatment characteristics; and to determine whether patients in the subgroups differed on two important patient outcomes: functional status and quality of life (QOL). DESIGN Descriptive, correlational study. SETTING Four outpatient oncology practices in northern California. SAMPLE 191 outpatients with cancer receiving active treatment. METHODS Patients completed a demographic questionnaire, Karnofsky Performance Status scale, Lee Fatigue Scale, General Sleep Disturbance Scale, Center for Epidemiological Studies Depression Scale, Multidimensional Quality-of-Life Scale Cancer, and a numeric rating scale of worst pain intensity. Medical records were reviewed for disease and treatment information. Cluster analysis was used to identify patient subgroups based on patients symptom experiences. Differences in demographic, disease, and treatment characteristics as well as in outcomes were evaluated using analysis of variance and chi square analysis. MAIN RESEARCH VARIABLES Subgroup membership, fatigue, sleep disturbance, depression, pain, functional status, and QOL. FINDINGS Four relatively distinct patient subgroups were identified based on patients experiences with four highly prevalent and related symptoms. CONCLUSIONS The subgroup of patients who reported low levels of all four symptoms reported the best functional status and QOL. IMPLICATIONS FOR NURSING The findings from this study need to be replicated before definitive clinical practice recommendations can be made. Until that time, clinicians need to assess patients for the occurrence of multiple symptoms that may place them at increased risk for poorer outcomes.

Identification of Four Gene Variants Associated with Myocardial Infarction

Family history is a major risk factor for myocardial infarction (MI). However, known gene variants associated with MI cannot fully explain the genetic component of MI risk. We hypothesized that a gene-centric association study that was not limited to candidate genes could identify novel genetic associations with MI. We studied 11,053 single-nucleotide polymorphisms (SNPs) in 6,891 genes, focusing on SNPs that could influence gene function to increase the likelihood of identifying disease-causing gene variants. To minimize false-positive associations generated by multiple testing, two studies were used to identify a limited number of nominally associated SNPs; a third study tested the hypotheses that these SNPs are associated with MI. In the initial study (of 340 cases and 346 controls), 637 SNPs were associated with MI (P<.05); these were evaluated in a second study (of 445 cases and 606 controls), and 31 of the 637 SNPs were associated with MI (P<.05) and had the same risk allele as in the first study. For each of these 31 SNPs, we tested the hypothesis that it is associated with MI, using a third study (of 560 cases and 891 controls). We found that four of these gene variants were associated with MI (P<.05; false-discovery rate <10%) and had the same risk allele as in the first two studies. These gene variants encode the cytoskeletal protein palladin (KIAA0992 [odds ratio (OR) 1.40]), a tyrosine kinase (ROS1 [OR 1.75]), and two G protein-coupled receptors (TAS2R50 [OR 1.58] and OR13G1 [OR 1.40]); all ORs are for carriers of two versus zero risk alleles. These findings could lead to a better understanding of MI pathophysiology and improved patient risk assessment.

Mutations in LMF1 cause combined lipase deficiency and severe hypertriglyceridemia.

Hypertriglyceridemia is a hallmark of many disorders, including metabolic syndrome, diabetes, atherosclerosis and obesity. A well-known cause is the deficiency of lipoprotein lipase (LPL), a key enzyme in plasma triglyceride hydrolysis. Mice carrying the combined lipase deficiency (cld) mutation show severe hypertriglyceridemia owing to a decrease in the activity of LPL and a related enzyme, hepatic lipase (HL), caused by impaired maturation of nascent LPL and hepatic lipase polypeptides in the endoplasmic reticulum (ER). Here we identify the gene containing the cld mutation as Tmem112 and rename it Lmf1 (Lipase maturation factor 1). Lmf1 encodes a transmembrane protein with an evolutionarily conserved domain of unknown function that localizes to the ER. A human subject homozygous for a deleterious mutation in LMF1 also shows combined lipase deficiency with concomitant hypertriglyceridemia and associated disorders. Thus, through its profound effect on lipase activity, LMF1 emerges as an important candidate gene in hypertriglyceridemia.

A Genome Scan for Familial Combined Hyperlipidemia Reveals Evidence of Linkage with a Locus on Chromosome 11

Familial combined hyperlipidemia (FCHL) is a common familial lipid disorder characterized by a variable pattern of elevated levels of plasma cholesterol and/or triglycerides. It is present in 10%-20% of patients with premature coronary heart disease. The genetic etiology of the disease, including the number of genes involved and the magnitude of their effects, is unknown. Using a subset of 35 Dutch families ascertained for FCHL, we screened the genome, with a panel of 399 genetic markers, for chromosomal regions linked to genes contributing to FCHL. The results were analyzed by use of parametric-linkage methods in a two-stage study design. Four loci, on chromosomes 2p, 11p, 16q, and 19q, exhibited suggestive evidence for linkage with FCHL (LOD scores of 1.3-2.6). Markers within each of these regions were then examined in the original sample and in additional Dutch families with FCHL. The locus on chromosome 2 failed to show evidence for linkage, and the loci on chromosome 16q and 19q yielded only equivocal or suggestive evidence for linkage. However, one locus, near marker D11S1324 on the short arm of human chromosome 11, continued to show evidence for linkage with FCHL, in the second stage of this design. This region does not contain any strong candidate genes. These results provide evidence for a candidate chromosomal region for FCHL and support the concept that FCHL is complex and heterogeneous.

Genetic analysis of a polymorphism in the human apoA-V gene effect on plasma lipids

Recent discovery and characterization of APOAV suggests a role in metabolism of triglyceride (TG)-rich lipoproteins. Previously, variation at the APOAV locus was shown to modestly influence plasma TGs in normolipidemic samples. The aims of this study were to assess the effects of a polymorphism in APOAV (T-1131C) in terms of its frequency among three dyslipidemic populations and a control population, differences of allele frequency across available ethnic groups, and associations with specific lipoprotein TG and cholesterol compartments. We found a striking elevation in the frequency of the rare allele in a Chinese population (P = 0.0002) compared with Hispanic and European populations. The rare allele of the polymorphism was associated with elevated plasma TG (P = 0.012), VLDL cholesterol (P = 0.0007), and VLDL TG (P = 0.012), LDL TG (P = 0.003), and HDL TG (P = 0.016). Linear regression models predict that possession of the rare allele elevates plasma TG by 21 mg/dl (P = 0.009) and VLDL cholesterol by 8 mg/dl (P = 0.0001), and reduces HDL cholesterol by 2 mg/dl (P = 0.017). The association of the polymorphism with altered lipoprotein profiles was observed in combined hyperlipidemia, hypoalphalipoproteinemia, and hyperalphalipoproteinemia, and in controls. These findings indicate that APOAV is an important determinant of plasma TG and lipoprotein cholesterol, and is potentially a risk factor for cardiovascular disease.

A review of the prevalence and impact of multiple symptoms in oncology patients.

Findings from several studies suggest that oncology patients undergoing active treatment experience multiple symptoms, and that these symptoms can have a negative effect on patient outcomes. However, no systematic review has summarized the findings from studies that assessed multiple symptoms in these patients. Therefore, the purposes of this review were to: 1) compare and contrast the characteristics of the three most commonly used instruments to measure multiple symptoms; 2) summarize the prevalence rates for multiple symptoms in studies of oncology patients receiving active treatment; 3) describe the relationships among selected demographic, disease, and treatment characteristics and multiple symptoms; and 4) describe the relationships between the occurrence of multiple symptoms and patient outcomes (i.e., functional status, quality of life). Only 18 studies were found that met the inclusion criteria for this review. The majority of the studies were cross-sectional with sample sizes that ranged from 26 to 527. Approximately 40% of patients experienced more than one symptom. However, little is known about the relationships between demographic and clinical characteristics and the occurrence of multiple symptoms. Findings from this review suggest that the occurrence of multiple symptoms is associated with decreased functional status and quality of life. However, given the large number of oncology patients who undergo active treatment each year, additional research is warranted on the prevalence and impact of multiple symptoms. Only when this descriptive research is completed with homogenous samples of patients in terms of cancer diagnoses and treatments can intervention studies for multiple symptoms be developed and tested.

Symptom Experience in HIV-Infected Adults: A Function of Demographic and Clinical Characteristics

Personal characteristics that interact with both HIV diagnosis and its medical management can influence symptom experience. Little is known about how symptoms in populations with chronic illness vary by age, sex, or socioeconomic factors. As part of an ongoing prospective longitudinal study, this report describes symptoms experienced by 317 men and women living with HIV/AIDS. Participants were recruited at HIV clinics and community sites in the San Francisco Bay Area. Measures included the most recent CD4 cell count and viral load from the medical record, demographic and treatment variables, and the 32-item Memorial Symptom Assessment Scale to estimate prevalence, severity, and distress of each symptom and global symptom burden. The median number of symptoms was nine, and symptoms experienced by more than half the sample population included lack of energy (65%), drowsiness (57%), difficulty sleeping (56%), and pain (55%). Global symptom burden was unrelated to age or CD4 cell count. Those with an AIDS diagnosis had significantly higher symptom burden scores, as did those currently receiving antiretroviral therapy. African Americans reported fewer symptoms than Caucasians or Mixed/Other race, and women reported more symptom burden after controlling for AIDS diagnosis and race. Because high symptom burden is more likely to precipitate self-care strategies that may potentially be ineffective, strategies for symptom management would be better guided by tailored interventions from health care providers.

Preliminary Evidence of a Genetic Association Between Tumor Necrosis Factor Alpha and the Severity of Sleep Disturbance and Morning Fatigue

Although fatigue and sleep disturbance are prevalent symptoms in oncology patients and their family caregivers, little is known about the factors that contribute to interindividual variability in symptom severity ratings as well as in their underlying biological mechanisms. In this study, we sought to determine whether a functional genetic variation in a prominent proinflammatory cytokine, tumor necrosis factor-alpha (TNFA-308G>A [rs1800629] promoter polymorphism) was associated with overall ratings of sleep disturbance and fatigue as well as with the trajectories of these symptoms. Over 6 months, participants completed standardized measures of sleep disturbance and fatigue. Multiple linear regression was used to assess the effect of the TNFA genotype and other covariates on mean sleep disturbance and fatigue scores. Hierarchical linear modeling was used to determine the effect of TNFA genotype on the trajectories of these symptoms. Common allele homozygotes reported higher levels of sleep disturbance (p = .09) and morning fatigue (p = .02) than minor allele carriers. Multivariate analyses demonstrated that age and genotype were predictors of both mean symptom scores and the trajectories of these symptoms. Findings provide preliminary evidence of an association between a functional promoter polymorphism in the TNFA gene and the severity of sleep disturbance and morning fatigue in oncology patients and their family caregivers.