Loss of DNA repair mechanisms in cardiac myocytes induce dilated cardiomyopathy

Cardiomyopathy is a progressive disease of the myocardium leading to impaired contractility. Genotoxic cancer therapies are known to be potent drivers of cardiomyopathy, whereas causes of spontaneous disease remain unclear. To test the hypothesis that endogenous genotoxic stress contributes to cardiomyopathy, we deleted the DNA repair gene Ercc1 specifically in striated muscle using a floxed allele of Ercc1 and mice expressing Cre under control of the muscle-specific creatinine kinase (Ckmm) promoter or depleted systemically (Ercc1^−/D mice). Ckmm-Cre^+/−;Ercc1^−/fl mice expired suddenly of heart disease by 7 months of age. As young adults, the hearts of Ckmm-Cre^+/−;Ercc1^−/fl mice were structurally and functionally normal, but by 6-months-of-age, there was significant ventricular dilation, wall thinning, interstitial fibrosis, and systolic dysfunction indicative of dilated cardiomyopathy. Cardiac tissue from the tissue-specific or systemic model showed increased apoptosis and cardiac myocytes from Ckmm-Cre^+/-;Ercc1^−/fl mice were hypersensitive to genotoxins, resulting in apoptosis. p53 levels and target gene expression, including several antioxidants, were increased in cardiac tissue from Ckmm-Cre^+/−;Ercc1^−/fl and Ercc1^−/D mice. Despite this, cardiac tissue from older mutant mice showed evidence of increased oxidative stress. Genetic or pharmacologic inhibition of p53 attenuated apoptosis and improved disease markers. Similarly, overexpression of mitochondrial-targeted catalase improved disease markers. Together, these data support the conclusion that DNA damage produced endogenously can drive cardiac disease and does so mechanistically via chronic activation of p53 and increased oxidative stress, driving cardiac myocyte apoptosis, dilated cardiomyopathy, and sudden death.     

Phenotypic effects of overexpression of Agrobacterium rhizogenes T-DNA ORF13 in transgenic tobacco plants are mediated by diffusible factor(s)

Nicotiana tabacum cv. Xanthi transgenic plants expressing ORF13 of Agrobacterium rhizogenes 8196 T-DNA under the 35S RNA promoter from the cauliflower mosaic virus displayed developmental abnormalities. They were small, with short and variable internodal lengths, their root systems were poorly developed; leaves were small, asymmetric, rounded, wrinkled and dark green; flowers were short, and irregularly shaped. They exhibited reduced apical dominance and regularly produced offshoots at the base of the plant. This phenotype was also exhibited by offshoots of normal N. tabacum cv. Xanthi stock grafted with a transgenic scion indicating that expression of ORF13 influences plant development via diffusible factor(s).     

Pattern-based clustering of daily weigh-in trajectories using dynamic time warping

“Smart”-scales are a new tool for frequent monitoring of weight change as well as weigh-in behavior. These scales give researchers the opportunity to discover patterns in the frequency that individuals weigh themselves over time, and how these patterns are associated with overall weight loss. Our motivating data come from an 18-month behavioral weight loss study of 55 adults classified as overweight or obese who were instructed to weigh themselves daily. Adherence to daily weigh-in routines produces a binary times series for each subject, indicating whether a participant weighed in on a given day. To characterize weigh-in by time-invariant patterns rather than overall adherence, we propose using hierarchical clustering with dynamic time warping (DTW). We perform an extensive simulation study to evaluate the performance of DTW compared to Euclidean and Jaccard distances to recover underlying patterns in adherence time series. In addition, we compare cluster performance using cluster validation indices (CVIs) under the single, average, complete, and Ward linkages and evaluate how internal and external CVIs compare for clustering binary time series. We apply conclusions from the simulation to cluster our real data and summarize observed weigh-in patterns. Our analysis finds that the adherence trajectory pattern is significantly associated with weight loss.     

Possible involvement of inhibin in altered follicle-stimulating hormone (FSH) secretion during dissociated luteinizing hormone (LH) and FSH release: unilateral castration and experimental cryptorchidism

Male rats were either unilaterally or bilaterally castrated, or were rendered cryptorchid when they were either 15 or 45 days old. Subsequently, blood was sampled over the next several weeks and plasma luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T), and immunoreactive inhibin-alpha (irI alpha) levels were measured by specific radioimmunoassays (RIAs). At the end of the experiment, gonadal expression of inhibin-alpha, inhibin-beta A, and inhibin-beta B subunits was measured by S1 nuclease analysis and in situ hybridization. In both age groups, bilateral castration (BC) produced the expected marked (p less than or equal to 0.01) increases in plasma LH and FSH levels, and concomitant decreases in T and irI alpha secretion within 1 - 2 days after surgery. In 15-day-old animals, unilateral castration (UC) significantly increased FSH and decreased circulating levels of irI alpha, but did not measurably alter LH or androgen production. At 7 days after surgery, the level of inhibin mRNA in the remaining testis was unchanged. In 45-day-old animals, UC caused a measurable increase in FSH, with little or no changes in the circulating levels of irI alpha. Plasma T levels were lowered (p less than or equal to 0.05) by UC; however, there were no statistical changes in LH levels in these UC rats. Finally, T administration markedly reversed UC-induced increase in FSH secretion in both age groups. Androgen therapy also interfered with inhibin release in 45-day-old, but not in 15-day-old rats. In rats 15 days old at the time of surgery, cryptorchidism produced a small but measurable increase (p less than or equal to 0.05) in LH release at Week 6 only, which was accompanied by a significant (p less than or equal to 0.01) decline in T secretion. Plasma FSH levels were elevated at all times in cryptorchid rats, and at 2, 4, and 6 wk, these levels were not statistically distinguishable (p greater than 0.05) from those of castrated animals. In this group of rats, cryptorchidism caused a transient increase (p less than or equal to 0.05) in irI alpha values 1 wk after surgery, but no changes at later times. Finally, measurement of testicular inhibin-alpha subunit messenger RNA (mRNA) levels showed an approximately 2-fold increase compared to total RNA levels in the testis. However, because of the significant decrease in total RNA levels per testis caused by cryptorchidism, the absolute change in inhibin-alpha subunit mRNA levels per testis corresponded to an approximately 3-fold decrease.(ABSTRACT TRUNCATED AT 400 WORDS)     

Cleavage of double-stranded DNA by manganese tris(methylpyridiniumyl)porphyrin linked to 3′-spermine oligonucleotides

 Cleavage of double-stranded DNA was performed with cationic manganese porphyrin complexes linked via a spermine tether to the 3′- or 5′-side of triple-helix-forming oligonucleotides (cleaver-TFO conjugates). The targeted sequence was a 15-polypurine sequence present in the env gene of HIV-1 (positions 7301–7315). The presently used TFOs contain only thymine and 5-methylcytosine residues and one adenine at the 3′-end in order to be able to easily introduce a 3′-polyamine linker by reductive amination of the corresponding 3′-apurinic polypyrimidine oligonucleotides. With this method we prepared these TFO-cleaver conjugates in 45% yield with only two equivalents of the Mn-TrisMPyP-COOH precursor. These new metalloporphyrin-TFO conjugates were able to cleave a complementary 45-mer duplex at 10 nM concentration with only ten equivalents of TFO-cleaver. Conjugates without spermine, without 5-methylcytosine, with a random sequence or with the managanese porphyrin-spermine entity on the 5′-end of TFOs were synthesized for comparative studies. Received: 6 December 1995 / Accepted: 5 February 1996     

Sucrose consumption in mice: Major influence of two genetic Loci affecting peripheral sensory responses

Individual variability in sucrose consumption is prominent in humans and other species. To investigate the genetic contribution to this complex behavior, we conducted behavioral, electrophysiological, and genetic studies, using male progeny of two inbred mouse strains (C57BL/6ByJ [B6] and 129/J [129]) and their F₂ hybrids. Two loci on Chromosome (Chr) 4 were responsible for over 50% of the genetic variability in sucrose intake. These loci apparently modulated intake by altering peripheral neural responses to sucrose. One locus affected the response threshold, whereas the other affected the response magnitude. These findings suggest that the majority of difference in sucrose intake between male B6 and 129 mice is due to polymorphisms of two genes that influence receptor or peripheral nervous system activity. Received: 27 January 1997 / Accepted: 17 March 1997     

Propylthiouracil Tasting: Determination of Underlying Threshold Distributions using Maximum Likelihood

The ability to taste low concentrations of propylthiouracil(PROP) and related bitter compounds is heritable. The currentanalysis determines whether the distribution of PROP taste thresholdsis consistent with an additive or a dominant mode of Mendeliantransmission. To that end, the lowest concentration of PROPdetectable was determined for 1015 subjects and models of bi-or tri-modal distributions of PROP taste thresholds were tested.The model with the greatest likelihood had three distributionsand followed an additive model of PROP taste sensitivity ifthe variances associated with the distributions were assumedto be equal. However, if the taste thresholds were transformedto remove skewness, or if the variances were unequal, then three-or two-distribution models were equally likely. Resolution ofthe mode of inheritance for bitter taste perception awaits additionalfamily studies and the characterization of the molecular basisof taste perception for these bitter compounds. Chem. Senses20: 529–533, 1995.     

Cleavage of double-stranded DNA by 'metalloporphyrin-linker-oligonucleotide' molecules: influence of the linker.

Manganese porphyrin-linker-triple-helix-forming oligonucleotide molecules were prepared and their ability to cleave in vitro a double-stranded DNA target present in the HIV-1 genome was studied. The nature of the linker is a determining factor of the cleavage efficiency. Cleavage yields as high as 80% were observed when the linker was a spermine residue and in the absence of a large excess of free spermine known to stabilize triplex structures. The hydrophobic nature of aliphatic diamine linker modified the cleaver-DNA interactions and reduced the efficiency of DNA cleavage.