Effects of mitoquinone (MitoQ) supplementation during boar semen cryopreservation on sperm quality, antioxidant status and mitochondrial proteomics.

Mitochondria are the most important organelles and the main reactive oxygen species producers in spermatozoa. The objective of this study was to investigate the effects of mitochondria-targeted antioxidant mitoquinone (MitoQ) supplementation in boar semen extender during cryopreservation on sperm quality, antioxidant status and the changes of sperm mitochondrial proteomic profile. Semen collected from 10 Large White boars was cryopreserved in lactose-egg yolk extender supplemented with various concentrations of MitoQ (0, 5, 10, 20 and 40 µM). After thawing, sperm characteristics, antioxidant status and the abundance of hexose transporters (GLUT 3 and 8) were analyzed. The comprehensive mitochondrial proteomic profiling was performed on spermatozoa in the control and MitoQ10 groups. Supplementation with 10 µM of MitoQ resulted in the highest post-thaw sperm motility and kinematics. Sperm quality, antioxidant capacity and glucose transporter abundance of frozen-thawed boar sperm were also elevated in the MitoQ10 group. Excessive MitoQ (40 µM) supplementation induced a reduction of sperm motility parameters, sperm quality and antioxidant status and the abundance of GLUT3 and 8 proteins. A total of 189 proteins were defied as differentially expressed proteins (DEPs) using fold change (FC) > 1.2 with P < 0.05, and 33 of them were dramatically (FC > 1.5) regulated by MitoQ. These DEPs are mainly involved in sperm motility, energy metabolism and oxidative phosphorylation. Our data suggest that the beneficial effect of MitoQ on cryopreserved boar semen is achieved by regulating sperm antioxidant capacity and the mitochondrial proteins related to motility and metabolism.

Skip segment Hirschsprung's disease: diagnostic clues and surgical management.

It is challenging to establish a definitive diagnosis and initiate timely management for skip segment Hirschsprung's disease (SSHD). Herein, we report three cases of SSHD at our institution between December 2008 and March 2018. Patient #1 was misdiagnosed and underwent three successive operations within 2 years. Patient #2 and #3 were diagnosed timely based on previous experience. A segmental narrowing detected by barium enema may raise the possibility of SSHD. Laparoscopic-guided multipoint biopsy is regarded as a mini-invasive and purposeful way to take representative samples after locating the segmental narrowing intraoperatively and accurate the final diagnosis. The laparoscopic-assisted pull-through procedure with radical resection from the distal rectum to the most proximal margin of the diseased skip segment is safe and effective in treating patients with SSHD.Level of evidence: Level III.

Sphingomyelin synthase 2 activity and liver steatosis: an effect of ceramide-mediated peroxisome proliferator-activated receptor γ2 suppression.

OBJECTIVE: Sphingolipid de novo biosynthesis is related to nonalcoholic fatty liver disease or hepatic steatosis. However, the mechanism is still unclear. Sphingomyelin synthase (SMS), using ceramide as one of the substrates to produce sphingomyelin, sits at the crossroads of sphingolipid biosynthesis. SMS has 2 isoforms: SMS1 and SMS2. SMS2 is the major isoform in liver. APPROACH AND RESULTS: To investigate the relationship between liver SMS2 activity-mediated sphingolipid changes and hepatic steatosis, we used 2 mouse models: Sms2 liver-specific transgenic and Sms2 knockout mice. We found that Sms2 liver-specific transgenic livers have lower ceramide and higher sphingomyelin, whereas Sms2 knockout livers have higher ceramide and lower sphingomyelin. We also found that liver Sms2 overexpression promoted fatty acid uptake and liver steatosis, whereas Sms2 deficiency had an opposite effect in comparison with their respective controls. Importantly, the exogenous ceramide supplementation to Huh7 cells, a human hepatoma cell line, reduced the expression of peroxisome proliferator-activated receptor γ2 and its target genes, Cd36 and Fsp27. Peroxisome proliferator-activated receptor γ reporter analysis confirmed this phenomenon. Furthermore, peroxisome proliferator-activated receptor γ antagonist treatment significantly decreased triglyceride accumulation in Sms2 liver-specific transgenic liver. CONCLUSIONS: We attributed these effects to ceramide that can suppress peroxisome proliferator-activated receptor γ2, thus reducing the expression of Cd36 and Fsp27 and reducing liver steatosis. After all, SMS2 inhibition in the liver could diminish liver steatosis.

High-dose atorvastatin causes a rapid sustained increase in human serum PCSK9 and disrupts its correlation with LDL cholesterol.

Proprotein convertase subtilisin kexin type 9 (PCSK9) is a key regulator of serum LDL-cholesterol (LDL-C) levels. PCSK9 is secreted by the liver into the plasma and binds the hepatic LDL receptor (LDLR), causing its subsequent degradation. We first demonstrated that a moderate dose of atorvastatin (40 mg) increases PCSK9 serum levels, suggesting why increasing statin doses may have diminished efficacy with regard to further LDL-C lowering. Since that initial observation, at least two other groups have reported statin-induced PCSK9 increases. To date, no analysis of the effect of high-dose atorvastatin (80 mg) on PCSK9 over time has been conducted. Therefore, we studied the time course of atorvastatin (80 mg) in human subjects. We measured PCSK9 and lipid levels during a 2-week lead-in baseline period and every 4 weeks thereafter for 16 weeks. We observed that atorvastatin (80 mg) caused a rapid 47% increase in serum PCSK9 at 4 weeks that was sustained throughout 16 weeks of dosing. Importantly, while PCSK9 levels were highly correlated with total cholesterol (TC), LDL-C, and triglyceride (TG) levels at baseline, atorvastatin (80 mg) completely abolished all of these correlations. Together, these results further suggest an explanation for why increasing doses of statins fail to achieve proportional LDL-C lowering.

Impaired de novo choline synthesis explains why phosphatidylethanolamine N-methyltransferase-deficient mice are protected from diet-induced obesity.

Phosphatidylcholine (PC) is synthesized from choline via the CDP-choline pathway. Liver cells can also synthesize PC via the sequential methylation of phosphatidylethanolamine, catalyzed by phosphatidylethanolamine N-methyltransferase (PEMT). The current study investigates whether or not hepatic PC biosynthesis is linked to diet-induced obesity. Pemt(+/+) mice fed a high fat diet for 10 weeks increased in body mass by 60% and displayed insulin resistance, whereas Pemt(-/-) mice did not. Compared with Pemt(+/+) mice, Pemt(-/-) mice had increased energy expenditure and maintained normal peripheral insulin sensitivity; however, they developed hepatomegaly and steatosis. In contrast, mice with impaired biosynthesis of PC via the CDP-choline pathway in liver became obese when fed a high fat diet. We, therefore, hypothesized that insufficient choline, rather than decreased hepatic phosphatidylcholine, was responsible for the lack of weight gain in Pemt(-/-) mice despite the presence of 1.3 g of choline/kg high fat diet. Supplementation with an additional 2.7 g of choline (but not betaine)/kg of diet normalized energy metabolism, weight gain, and insulin resistance in high fat diet-fed Pemt(-/-) mice. Furthermore, Pemt(+/+) mice that were fed a choline-deficient diet had increased oxygen consumption, had improved glucose tolerance, and gained less weight. Thus, de novo synthesis of choline via PEMT has a previously unappreciated role in regulating whole body energy metabolism.