Phosphatidylethanolamine N-methyltransferase (PEMT) Knockout Mice Exhibit Worse Alcohol-Induced Liver Injury than Wildtype Mice

Phosphatidylethanolamine N-methyltransferase (PEMT) is an enzyme that catalyzes the successive transfer of 3 methyl groups from S-adenosylmethionine (SAM) to phosphatidylethanolamine (PE) to generate phosphatidylcholine (PC). PC is vital for exporting fat out of the liver, ultimately preventing hepatic steatosis. Alcohol also induces steatosis partly through damaging this pathway, so the purpose of this study was to investigate the relationship between alcohol and PEMT in the liver. PEMT -/- (KO) and wild-type (WT) mice were subjected to a chronic + binge alcohol treatment, and both serum and liver samples were analyzed. Triglyceride quantification, SAM and S-adenosylhomocysteine (SAH) levels, and histological analyses were performed on liver samples, while ALT levels were determined from serum samples. Our study showed that ethanol-fed PEMT KO mice exhibited worse liver injury compared to other treatment groups. Our results show increased triglyceride levels, increased ALT levels, decreased SAM:SAH ratio, and increased liver to body weight ratio. From these findings, we conclude that additional liver damage is observed with the combination of alcohol feeding and absence of the PEMT enzyme. The mechanism by which these two factors affect one another is a key area of future study.https://digitalcommons.unmc.edu/surp2021/1016/thumbnail.jp

Elevated S-Adenosylhomocysteine Induces Adipocyte Dysfunction to Promote Alcohol-Associated Liver Steatosis

It has been previously shown that chronic ethanol administration-induced increase in adipose tissue lipolysis and reduction in the secretion of protective adipokines collectively contribute to alcohol-associated liver disease (ALD) pathogenesis. Further studies have revealed that increased adipose S-adenosylhomocysteine (SAH) levels generate methylation defects that promote lipolysis. Here, we hypothesized that increased intracellular SAH alone causes additional related pathological changes in adipose tissue as seen with alcohol administration. To test this, we used 3-deazaadenosine (DZA), which selectively elevates intracellular SAH levels by blocking its hydrolysis. Fully differentiated 3T3-L1 adipocytes were treated in vitro for 48 h with DZA and analysed for lipolysis, adipokine release and differentiation status. DZA treatment enhanced adipocyte lipolysis, as judged by lower levels of intracellular triglycerides, reduced lipid droplet sizes and higher levels of glycerol and free fatty acids released into the culture medium. These findings coincided with activation of both adipose triglyceride lipase and hormone sensitive lipase. DZA treatment also significantly reduced adipocyte differentiation factors, impaired adiponectin and leptin secretion but increased release of pro-inflammatory cytokines, IL-6, TNF and MCP-1. Together, our results demonstrate that elevation of intracellular SAH alone by DZA treatment of 3T3-L1 adipocytes induces lipolysis and dysregulates adipokine secretion. Selective elevation of intracellular SAH by DZA treatment mimics ethanol\u27s effects and induces adipose dysfunction. We conclude that alcohol-induced elevations in adipose SAH levels contribute to the pathogenesis and progression of ALD

A prospective cohort study comparing the reactogenicity of trivalent influenza vaccine in pregnant and non-pregnant women

Background: Influenza vaccination during pregnancy can prevent serious illness in expectant mothers and provide protection to newborns; however, historically uptake has been limited due to a number of factors, including safety concerns. Symptomatic complaints are common during pregnancy and may be mistakenly associated with reactions to trivalent influenza vaccine (TIV). To investigate this, we compared post-vaccination events self-reported by pregnant women to events reported by non-pregnant women receiving TIV. Methods: A prospective cohort of 1,086 pregnant women and 314 non-pregnant female healthcare workers (HCWs) who received TIV between March-May 2014 were followed-up seven days post-vaccination to assess local and systemic adverse events following immunisation (AEFIs). Women were surveyed by text message regarding perceived reactions to TIV. Those reporting an AEFI completed an interview by telephone or mobile phone to ascertain details. Logistic regression models adjusting for age and residence were used to compare reactions reported by pregnant women and non-pregnant HCWs. Results: Similar proportions of pregnant women and non-pregnant, female HCWs reported ≥1 reaction following vaccination with TIV (13.0% and 17.3%, respectively; OR = 1.2 [95% CI: 0.8-1.8]). Non-pregnant, female HCWs were more likely to report fever or headache compared to pregnant women (OR: 4.6 [95% CI 2.1-10.3] and OR: 2.2 [95% CI 1.0-4.6], respectively). No other significant differences in reported symptoms were observed. No serious vaccine-associated adverse events were reported, and less than 2% of each group sought medical advice for a reaction. Conclusions: We found no evidence suggesting pregnant women are more likely to report adverse events following influenza vaccination when compared to non-pregnant female HCWs of similar age, and in some cases, pregnant women reported significantly fewer adverse events. These results further support the safety of TIV administered in pregnant women

Acute Ethanol-Induced Liver Injury is Prevented by Betaine Administration

Binge drinking is the most common form of excessive alcohol use. Repeated episodes of binge drinking cause multiple organ injuries, including liver damage. We previously demonstrated that chronic ethanol administration causes a decline in the intrahepatic ratio of S-adenosylmethionine (SAM) to S-adenosylhomocysteine (SAH). This decline causes impairments in essential methylation reactions that result in alcohol-induced fatty liver (steatosis) and other features of alcohol-associated liver disease (ALD). Co-treatment with betaine during chronic ethanol feeding, normalizes hepatocellular SAM:SAH ratio and alleviates many features of liver damage including steatosis. Here, we sought to examine whether betaine treatment similarly protects against liver injury in an alcohol binge-drinking model. We hypothesized that ethanol binge with prior or simultaneous betaine administration would prevent or attenuate acute alcohol-induced liver damage. Male C57Bl/6 mice were gavaged twice, 12 h apart, with either 6 g ethanol/kg BW or with an equal volume/kg BW of 0.9% NaCl. Two separate groups of mice (n = 5/group) were gavaged with 4 g betaine/kg BW, either 2 h before or simultaneously with the ethanol or saline gavages. All mice were sacrificed 8 h after the last gavage and serum and liver parameters were quantified. Ethanol binges caused a 50% decrease in hepatic SAM:SAH ratio and a \u3e3-fold rise in liver triglycerides (p ≤ 0.05). These latter changes were accompanied by elevated serum AST and ALT activities and blood alcohol concentrations (BAC) that were ∼three-times higher than the legal limit of intoxication in humans. Mice that were treated with betaine 2 h before or simultaneously with the ethanol binges exhibited similar BAC as in mice given ethanol-alone. Both betaine treatments significantly elevated hepatic SAM levels thereby normalizing the SAM:SAH ratio and attenuating hepatic steatosis and other injury parameters, compared with mice given ethanol alone. Simultaneous betaine co-administration with ethanol was more effective in preventing or attenuating liver injury than betaine given before ethanol gavage. Our findings confirm the potential therapeutic value of betaine administration in preventing liver injury after binge drinking in an animal model

Regulation of the hTERT telomerase catalytic subunit by the c-Abl tyrosine kinase

BACKGROUND: Telomeres consist of repetitive (TTAGGG) DNA sequences that are maintained by the multisubunit telomerase ribonucleoprotein. Telomerase consists of an RNA, which serves as template for the sequence tracts, and a catalytic subunit that functions in reverse transcription of the RNA template. Cloning and characterization of the human catalytic subunit of telomerase (hTERT) has supported a role in cell transformation. How telomerase activity is regulated, however, is largely unknown. RESULTS: We show here that hTERT associates directly with the c-Abl protein tyrosine kinase. We also found that c-Abl phosphorylates hTERT and inhibits hTERT activity. Moreover, our findings demonstrate that exposure of cells to ionizing radiation induces tyrosine phosphorylation of hTERT by a c-Abl-dependent mechanism. The functional significance of the c-Abl-hTERT interaction is supported by the demonstration that cells deficient in c-Abl show telomere lengthening. CONCLUSIONS: The ubiquitously expressed c-Abl tyrosine kinase is activated by DNA double-strand breaks. Our finding of telomere lengthening in c-Abl-deficient cells and the functional interactions between c-Abl and hTERT support a role for c-Abl in the regulation of telomerase function

Ultrasound- Versus Fluoroscopy-Guided Strategy for Transfemoral Transcatheter Aortic Valve Replacement Access: A Systematic Review and Meta-Analysis

Background:Access site vascular and bleeding complications remain problematic for patients undergoing transcatheter aortic valve replacement (TAVR). Ultrasound-guided transfemoral access approach has been suggested as a technique to reduce access site complications, but there is wide variation in adoption in TAVR. We performed a systematic review and meta-analysis to compare access site vascular and bleeding complications according to the Valve Academic Research Consortium-2 classification following the use of either ultrasound- or conventional fluoroscopy-guided transfemoral TAVR access.Methods:Medline, Embase, Web of Science, and The Cochrane Library were searched to November 2020 for studies comparing ultrasound- and fluoroscopy-guided access for transfemoral TAVR. A priori defined primary outcomes were extracted: (1) major, (2) minor, and (3) major and minor (total) access site vascular complications and (4) life-threatening/major, (5) minor, and (6) life-threatening, major, and minor (total) access site bleeding complications.Results:Eight observational studies (n=3875) were included, with a mean participant age of 82.8 years, STS score 5.81, and peripheral vascular disease in 23.5%. An ultrasound-guided approach was significantly associated with a reduced risk of total (Mantel-Haenszel odds ratio [MH-OR], 0.50 [95% CI, 0.35–0.73]), major (MH-OR, 0.51 [95% CI, 0.35–0.74]), and minor (MH-OR, 0.59 [95% CI, 0.38–0.91]) access site vascular complications. Ultrasound guidance was also significantly associated with total access site bleeding complications (MH-OR, 0.59 [95% CI, 0.39–0.90]). The association remained significant in sensitivity analyses of maximally adjusted minor and total vascular access site complications (MH-OR, 0.51 [95% CI, 0.29–0.90]; MH-OR, 0.44 [95% CI, 0.20–0.99], respectively).Conclusions:In the absence of randomized studies, our data suggests a potential benefit for ultrasound guidance to obtain percutaneous femoral access in TAVR

How does coronary stent implantation impact on the status of the microcirculation during primary percutaneous coronary intervention in patients with ST-elevation myocardial infarction?

Aims Primary percutaneous coronary intervention (PPCI) is the optimal treatment for patients presenting with ST-elevation myocardial infarction (STEMI). An elevated index of microcirculatory resistance (IMR) reflects microvascular function and when measured after PPCI, it can predict an adverse clinical outcome. We measured coronary microvascular function in STEMI patients and compared sequential changes before and after stent implantation. Methods and results In 85 STEMI patients, fractional flow reserve, coronary flow reserve, and IMR were measured using a pressure wire (Certus, St Jude Medical, St Paul, MN, USA) immediately before and after stent implantation. Stenting significantly improved all of the measured parameters of coronary physiology including IMR from 67.7 [interquartile range (IQR): 56.2-95.8] to 36.7 (IQR: 22.7-59.5), P 40) in 28 (32.9%) patients. In 15 of these patients (17.6% of the cohort), only a partial reduction in IMR occurred and these patients were more likely to be late presenters (pain to wire time >6 h). The extent of jeopardized myocardium [standardized beta: −0.26 (IMR unit/Bypass Angioplasty Revascularization Investigation score unit), P: 0.009] and pre-stenting IMR [standardized beta: −0.34 (IMR unit), P: 0.001] predicted a reduction in IMR after stenting (ΔIMR = post-stenting IMR − pre-stenting IMR), whereas thrombotic burden [standardized beta: 0.24 (IMR unit/thrombus score unit), P: 0.01] and deployed stent volume [standardized beta: 0.26 (IMR unit/mm3 of stent), P: 0.01] were associated with a potentially deleterious increase in IMR. Conclusion Improved perfusion of the myocardium by stent deployment during PPCI is not universal. The causes of impaired microvascular function at the completion of PPCI treatment are heterogeneous, but can reflect a later clinical presentation and/or the location and extent of the thrombotic burde