Metformin-associated Lactic Acidosis Induced by Excessive Alcohol Consumption.

A 65-year-old man with type 2 diabetes who was being treated with metformin developed lactic acidosis following excessive alcohol consumption. While an impaired renal function is a major risk factor for metformin-associated lactic acidosis (MALA), the patient's basal renal function was normal. Alcohol misuse reduces lactate clearance by utilizing nicotinamide adenine dinucleotides for ethanol oxidation, thereby promoting vulnerability to MALA. Nevertheless, as MALA in individuals with a normal renal function is extremely rare, the clinical picture of alcohol-induced MALA is unclear. We delineate the clinical picture and discuss the pathogenesis of alcohol-induced MALA based on our experience and previous case reports.

Direct Link Between Cardiac Failure and Global Cerebral Atrophy in a Young Adult: A Case Report on Reduced Cerebral Artery Blood Flow.

BACKGROUND Heart failure is associated with structural brain abnormalities, including atrophy of multiple brain regions. Previous studies have reported brain atrophy in middle-aged patients with systolic heart failure. In this report, we present the case of a 21-year-old woman with idiopathic dilated cardiomyopathy, cardiac failure, and global cerebral atrophy due to reduced cerebral artery blood flow. We also discuss the impact of brain atrophy in this young adult patient with severe heart failure and no risk factors for atherosclerosis. CASE REPORT A 21-year-old woman with dyspnea and leg edema was admitted to our hospital. After several examinations, an endomyocardial biopsy led to a diagnosis of idiopathic dilated cardiomyopathy, and transthoracic ultrasound cardiography revealed that her left ventricular ejection fraction was 36%. One year after the first hospitalization, her heart failure was classified as New York Heart Association Class III. Magnetic resonance imaging showed severe global brain atrophy, and single-photon emission computed tomography combined with brain computed tomography showed reduced blood flow to the entire brain. She had no risk factors for atherosclerosis and no atherosclerotic changes to her brain or carotid arteries, but her neuropsychological and neurological findings indicated more pronounced brain and cognitive dysfunction. CONCLUSIONS This young adult patient with idiopathic dilated cardiomyopathy, cardiac failure, and global cerebral atrophy showed reduced cerebral artery blood flow and cognitive impairment. The findings of this report indicate that low cardiac output may directly cause brain atrophy in patients with systolic heart failure.

siRNA screening identifies METTL9 as a histidine Nπ-methyltransferase that targets the proinflammatory protein S100A9.

Protein methylation is one of the most common post-translational modifications observed in basic amino acid residues, including lysine, arginine, and histidine. Histidine methylation occurs on the distal or proximal nitrogen atom of its imidazole ring, producing two isomers: Nτ-methylhistidine or Nπ-methylhistidine. However, the biological significance of protein histidine methylation remains largely unclear owing in part to the very limited knowledge about its contributing enzymes. Here, we identified mammalian seven-ß-strand methyltransferase METTL9 as a histidine Nπ-methyltransferase by siRNA screening coupled with methylhistidine analysis using LC-tandem MS. We demonstrated that METTL9 catalyzes Nπ-methylhistidine formation in the proinflammatory protein S100A9, but not that of myosin light chain kinase MYLK2, in vivo and in vitro. METTL9 does not affect the heterodimer formation of S100A9 and S100A8, although Nπ-methylation of S100A9 at His-107 overlaps with a zinc-binding site, attenuating its affinity for zinc. Given that S100A9 exerts an antimicrobial activity, probably by chelation of zinc essential for the growth of bacteria and fungi, METTL9-mediated S100A9 methylation might be involved in the innate immune response to bacterial and fungal infection. Thus, our findings suggest a functional consequence for protein histidine Nπ-methylation and may add a new layer of complexity to the regulatory mechanisms of post-translational methylation.

Repeated surgical treatment and long-term outcome of a cat with vertebral vascular hamartoma.

A 30-month-old Maine Coon presented with progressive proprioceptive ataxia, paraparesis, thoracolumbar pain, and decreased appetite. An extradural mass was detected within the left side of the 13th thoracic vertebral canal that compressed the spinal cord on magnetic resonance (MR) and was considered to be mineralized on computed tomography (CT) images. The resected mass was diagnosed as a vertebral vascular hamartoma. Clinical signs improved, but recurrence was diagnosed by MR and CT imaging at 7 months after surgery. Repeated excisional surgery yielded the same diagnosis and the clinical signs abated. Fifteen months after the second surgery, there was apparent vertebral deformation, but there was no further change on CT images by 29 months.

Gender differences in predictors of left ventricular myocardial relaxation in non-obese, healthy individuals.

BACKGROUND: Previous studies indicate that individuals with metabolic syndrome (MetS) might be at risk for left ventricular (LV) diastolic dysfunction. However, little is known about which metabolic factors contribute to the development of LV dysfunction in individuals who are not obese or overweight and who do not have diabetes mellitus and/or cardiovascular disease. METHODS: Participants without diabetes mellitus, systolic dysfunction, or other heart diseases underwent a thorough physical examination, including tissue Doppler echocardiography. A peak early mitral annular velocity (e') of <5.0 was designated as indicating abnormal LV myocardial relaxation (LVMR). We performed single and multiple logistic regression analyses of e' and cardiovascular risk factors, including MetS factors and indicators of major organ dysfunction. Normal-weight subjects (body mass index <25 kg/m2) were also analyzed. RESULTS: A total of 1055 individuals (mean age, 63 ± 13 years) participated, of which 307 (29.1%) had MetS and 199 (18.9%) had abnormal LVMR. Multiple logistic regression analysis revealed waist circumference (WC) (odds ratio [OR] 1.04, P < 0.05) and age (OR 1.10, P < 0.05) to be predictors of abnormal LVMR. In normal-weight subjects (n = 806), aging (OR 1.08, P < 0.01), abnormal WC (OR 3.80, P < 0.01), and renal dysfunction (OR 2.14, P < 0.01) were predictors of abnormal LVMR. Among MetS factors, abnormal WC in men (OR 3.70, P < 0.01) and high diastolic blood pressure (DBP) in women (OR 4.00, P = 0.01) were related to abnormal LVMR.

Amplification of a plasmid bearing a mammalian replication initiation region in chromosomal and extrachromosomal contexts.

Amplified genes in cancer cells reside on extrachromosomal double minutes (DMs) or chromosomal homogeneously staining regions (HSRs). We used a plasmid bearing a mammalian replication initiation region to model gene amplification. Recombination junctions in the amplified region were comprehensively identified and sequenced. The junctions consisted of truncated direct repeats (type 1) or inverted repeats (type 2) with or without spacing. All of these junctions were frequently detected in HSRs, whereas there were few type 1 or a unique type 2 flanked by a short inverted repeat in DMs. The junction sequences suggested a model in which the inverted repeats were generated by sister chromatid fusion. We were consistently able to detect anaphase chromatin bridges connected by the plasmid repeat, which were severed in the middle during mitosis. De novo HSR generation was observed in live cells, and each HSR was lengthened more rapidly than expected from the classical breakage/fusion/bridge model. Importantly, we found massive DNA synthesis at the broken anaphase bridge during the G1 to S phase, which could explain the rapid lengthening of the HSR. This mechanism may not operate in acentric DMs, where most of the junctions are eliminated and only those junctions produced through stable intermediates remain.

Interconversion of intra- and extra-chromosomal sites of gene amplification by modulation of gene expression and DNA methylation.

We previously showed that plasmids containing a mammalian replication initiation region and a matrix attachment region were efficiently amplified to few thousand copies per cell, and that they formed extrachromosomal double minutes (DMs) or chromosomal homogeneously staining regions (HSRs). In these structures, the plasmid sequence was arranged as a tandem repeats, and we suggested a mechanism of plasmid amplification. Since amplification was very efficient, easy, and convenient, it might be adapted to a novel method for protein production. In the current study, we found that gene expression from the tandem plasmid repeat was suppressed. We identified several strategies to overcome this suppression, including: (1) use of higher concentrations of antibiotic during cell selection; (2) treatment of cells with agents that influence DNA methylation (5-azacytidine) or histone acetylation (butyrate); (3) co-amplification of an insulator sequence; and (4) co-amplification of sequences that encode a transcriptional activator. Expression from the plasmid repeat was always higher at DMs compared to HSRs. We found that continuous activation of a plasmid-encoded inducible promoter prevented the generation of long HSRs, and favored amplification at DMs. Consistent with this finding, there was a synergistic effect of transcriptional activation and inhibition of DNA methylation on the fragmentation of long HSRs and the generation of DMs and short HSRs. Our results indicate that both transcriptional activation and DNA methylation regulate the interconversion between extra- and intra-chromosomal gene amplification. These results have important implications for both protein production technology, and the generation of chromosomal abnormalities found in human cancer cells.