Structure of a mammalian sperm cation channel complex.

The cation channel of sperm (CatSper) is essential for sperm motility and fertility1,2. CatSper comprises the pore-forming proteins CATSPER1-4 and multiple auxiliary subunits, including CATSPERß, γ, δ, ε, ζ, and EFCAB91,3-9. Here we report the cryo-electron microscopy (cryo-EM) structure of the CatSper complex isolated from mouse sperm. In the extracellular view, CATSPER1-4 conform to the conventional domain-swapped voltage-gated ion channel fold10, following a counterclockwise arrangement. The auxiliary subunits CATSPERß, γ, δ and ε-each of which contains a single transmembrane segment and a large extracellular domain-constitute a pavilion-like structure that stabilizes the entire complex through interactions with CATSPER4, 1, 3 and 2, respectively. Our EM map reveals several previously uncharacterized components, exemplified by the organic anion transporter SLCO6C1. We name this channel-transporter ultracomplex the CatSpermasome. The assembly and organization details of the CatSpermasome presented here lay the foundation for the development of CatSpermasome-related treatments for male infertility and non-hormonal contraceptives.

Structural basis of Notch recognition by human γ-secretase.

Aberrant cleavage of Notch by γ-secretase leads to several types of cancer, but how γ-secretase recognizes its substrate remains unknown. Here we report the cryo-electron microscopy structure of human γ-secretase in complex with a Notch fragment at a resolution of 2.7 Å. The transmembrane helix of Notch is surrounded by three transmembrane domains of PS1, and the carboxyl-terminal ß-strand of the Notch fragment forms a ß-sheet with two substrate-induced ß-strands of PS1 on the intracellular side. Formation of the hybrid ß-sheet is essential for substrate cleavage, which occurs at the carboxyl-terminal end of the Notch transmembrane helix. PS1 undergoes pronounced conformational rearrangement upon substrate binding. These features reveal the structural basis of Notch recognition and have implications for the recruitment of the amyloid precursor protein by γ-secretase.

Sex-determining region Y gene promotes liver fibrosis and accounts for sexual dimorphism in its pathophysiology.

BACKGROUND & AIMS: Men are more prone to develop and die from liver fibrosis than women. In this study, we aim to investigate how sex-determining region Y gene (SRY) in hepatocytes promotes liver fibrosis. METHODS: Hepatocyte-specific Sry knock-in (KI), Sry knockout (KO), and Sry KI with platelet-derived growth factor receptor α (Pdgfrα) KO mice were generated. Liver fibrosis was induced in mice by bile duct ligation for 2 weeks or carbon tetrachloride treatment for 6 weeks. In addition, primary hepatocytes, hepatic stellate cells (HSCs), and immortalized cell lines were used for in vitro studies and mechanistic investigation. RESULTS: Compared to females, the severity of toxin- or cholestasis-induced liver fibrosis is similarly increased in castrated and uncastrated male mice. Among all Y chromosome-encoded genes, SRY was the most significantly upregulated and consistently increased gene in fibrotic/cirrhotic livers in male patients and in mouse models. Sry KI mice developed exacerbated liver fibrosis, whereas Sry KO mice had alleviated liver fibrosis, compared to age- and sex-matched control mice after bile duct ligation or administration of carbon tetrachloride. Mechanistically, both our in vivo and in vitro studies illustrated that SRY in hepatocytes can transcriptionally regulate Pdgfrα expression, and promote HMGB1 (high mobility group box 1) release and subsequent HSC activation. Pdgfrα KO or treatment with the SRY inhibitor DAX1 in Sry KI mice abolished SRY-induced HMGB1 secretion and liver fibrosis. CONCLUSIONS: SRY is a strong pro-fibrotic factor and accounts for the sex disparity observed in liver fibrosis, suggesting its critical role as a potentially sex-specific therapeutic target for prevention and treatment of the disease. IMPACT AND IMPLICATION: We identified that a male-specific gene, sex-determining region Y gene (SRY), is a strong pro-fibrotic gene that accounts for the sex disparity observed in liver fibrosis. As such, SRY might be an appropriate target for surveillance and treatment of liver fibrosis in a sex-specific manner. Additionally, SRY might be a key player in the sexual dimorphism observed in hepatic pathophysiology more generally.

Epigenetic regulation and epigenetic memory resetting during plant rejuvenation.

Reversal of plant developmental status from the mature to the juvenile phase, thus leading to the restoration of the developmental potential, is referred to as plant rejuvenation. It involves multilayer regulation, including resetting gene expression patterns, chromatin remodeling, and histone modifications, eventually resulting in the restoration of juvenile characteristics. Although plants can be successfully rejuvenated using some forestry practices to restore juvenile morphology, physiology, and reproductive capabilities, studies on the epigenetic mechanisms underlying this process are in the nascent stage. This review provides an overview of the plant rejuvenation process and discusses the key epigenetic mechanisms involved in DNA methylation, histone modification, and chromatin remodeling in the process of rejuvenation, as well as the roles of small RNAs in this process. Additionally, we present new inquiries regarding the epigenetic regulation of plant rejuvenation, aiming to advance our understanding of rejuvenation in sexually and asexually propagated plants. Overall, we highlight the importance of epigenetic mechanisms in the regulation of plant rejuvenation, providing valuable insights into the complexity of this process.

Characterization of pollen tube development in distant hybridization of Chinese cork oak (Quercus variabilis L.).

MAIN CONCLUSION: This work mainly found that the stigma and style of Q. variabilis did not completely lose the specific recognition towards heterologous pollen, a fact which is different from previous studies. Quercus is the foundation species in the Northern Hemisphere, with extreme prevalence for interspecific hybridization. It is not yet entirely understood whether or how the pollen tube-female tissue interaction contributes to the "extensive hybridization" in oaks. Pollen storage conditions correlate with distant hybridization. We conducted hybridization experiments with Q. variabilis as female and Q. variabilis and Q. mongolica as male parents. And the differences in pollen tube (PT) development between intra- and distant interspecific hybridization were studied by fluorescence microscopy and scanning electron microscopy (SEM). Our results showed that -20 °C allowed pollen of both species to maintain some viability. Both Q. variabilis and Q. mongolica pollen germinated profusely on the stigmas. SEM results indicated that in the intraspecific hybridization, Q. variabilis pollen started to germinate at 6 h after pollination (hap), PTs elongated significantly at 12 hap, and entered the stigma at 24 hap. By contrast, Q. mongolica pollen germinated at 15 hap, and the PTs entered the stigma at 27 hap. By fluorescence microscopical studies it was observed that some PTs of Q. variabilis gathered at the style-joining at 96 hap, unlike the Q. mongolica which reached the style junction at 144 hap. The above results indicate that the abundant germination of heterologous pollen (HP) on the stigma and the "Feeble specificity recognition" of the stigma and transmitting tract to HP may create opportunities for the "extensive hybridization" of oaks. This work provides a sexual developmental reference for clarifying the causes of Quercus "extensive hybridization".

Physiologically based pharmacokinetic model combined with reverse dose method to study the nephrotoxic tolerance dose of tacrolimus.

Nephrotoxicity is the most common side effect that severely limits the clinical application of tacrolimus (TAC), an immunosuppressive agent used in kidney transplant patients. This study aimed to explore the tolerated dose of nephrotoxicity of TAC in individuals with different CYP3A5 genotypes and liver conditions. We established a human whole-body physiological pharmacokinetic (WB-PBPK) model and validated it using data from previous clinical studies. Following the injection of 1 mg/kg TAC into the tail veins of male rats, we developed a rat PBPK model utilizing the drug concentration-time curve obtained by LC-MS/MS. Next, we converted the established rat PBPK model into the human kidney PBPK model. To establish renal concentrations, the BMCL5 of the in vitro CCK-8 toxicity response curve (drug concentration range: 2-80 mol/L) was extrapolated. To further investigate the acceptable levels of nephrotoxicity for several distinct CYP3A5 genotypes and varied hepatic function populations, oral dosing regimens were extrapolated utilizing in vitro-in vivo extrapolation (IVIVE). The PBPK model indicated the tolerated doses of nephrotoxicity were 0.14-0.185 mg/kg (CYP3A5 expressors) and 0.13-0.155 mg/kg (CYP3A5 non-expressors) in normal healthy subjects and 0.07-0.09 mg/kg (CYP3A5 expressors) and 0.06-0.08 mg/kg (CYP3A5 non-expressors) in patients with mild hepatic insufficiency. Further, patients with moderate hepatic insufficiency tolerated doses of 0.045-0.06 mg/kg (CYP3A5 expressors) and 0.04-0.05 mg/kg (CYP3A5 non-expressors), while in patients with moderate hepatic insufficiency, doses of 0.028-0.04 mg/kg (CYP3A5 expressors) and 0.022-0.03 mg/kg (CYP3A5 non-expressors) were tolerated. Overall, our study highlights the combined usage of the PBPK model and the IVIVE approach as a valuable tool for predicting toxicity tolerated doses of a drug in a specific group.

SRY is a Key Mediator of Sexual Dimorphism in Hepatic Ischemia/Reperfusion Injury.

OBJECTIVES: To identify the role and mechanism of a male specific gene, SRY, in I/R-induced hepatic injury. BACKGROUND: Males are more vulnerable to I/R injury than females. However, the mechanism of these sex-based differences remains poorly defined. METHODS: Clinicopathologic data of patients who underwent hepatic resection were identified from an international multi-institutional database. Liver specific SRY TG mice were generated, and subjected to I/R insult with their littermate WT controls in vivo. In vitro experiments were performed by treating primary hepatocytes from TG and WT mice with hypoxia/reoxygen-ation stimulation. RESULTS: Clinical data showed that postoperative aminotransferase level, incidence of overall morbidity and liver failure were markedly higher among 1267 male versus 508 female patients who underwent hepatic resection. SRY was dramatically upregulated during hepatic I/R injury. Overexpression of SRY in male TG mice and ectopic expression of SRY in female TG mice exacerbated liver I/R injury compared with WTs as manifested by increased inflammatory reaction, oxidative stress and cell death in vivo and in vitro. Mechanistically, SRY interacts with Glycogen synthase kinase-3ß (GSK-3ß) and ß-catenin, and promotes phosphorylation and degradation of ß-catenin, leading to suppression of the downstream FOXOs, and activation of NF-κBand TLR4 signaling. Furthermore, activation of ß-catenin almost completely reversed the SRYoverexpression-mediated exacerbation of hepatic I/R damage. CONCLUSIONS: SRY is a novel hepatic I/R mediator that promotes hepatic inflammatory reaction, oxidative stress and cell necrosis via inhibiting Wnt/ß-catenin signaling, which accounts for the sex-based disparity in hepatic I/R injuries.

A nomogram model to predict prognosis of patients with hepatoblastoma.

BACKGROUND: Hepatoblastomas (HBs) are malignant liver tumors that most commonly develop in pediatric patients. Microvascular invasion may be a prognosis factor for patients with HBs. This study aimed to construct a model to predict the survival outcome in HBs. METHODS: We retrospectively analyzed the clinical data of 311 patients with HBs who underwent surgical resection at our institution between June 2014 and August 2021. First, patients were divided into two groups: those who had pathologic microvascular invasion (n = 146) and those who did not (n = 165). Propensity score-matched (PSM) analysis was carried out between the two groups. The preoperative parameters and overall survival (OS) rate were compared between the two groups. Second, all 311 patients were randomly divided into the training and validation cohort in a ratio of 4:1. A nomogram was created in the training cohort to visualize the prediction of OS. Moreover, the validation cohort was used for validation. RESULTS: Multivariate analysis suggested that age, histology type, microvascular invasion, multifocality, distant metastasis, and macrovascular involvement are independent prognostic factors for HBs. The nomogram showed good predictive ability in the training and validation cohorts with a C-index of 0.878 (95% CI, 0.831-0.925) and 0.847 (95% CI, 0.757-0.937), respectively. The calibration curve indicated good agreement between the prediction and observation for one-, two-, and three-year OS probabilities. CONCLUSION: By combining preoperative imaging results and other clinical data, we established a nomogram to predict OS probability for patients with HB, which could be a potential tool to guide personalized treatment.

Application of physiologically based pharmacokinetic modeling to predict the pharmacokinetics of telavancin in obesity with renal impairment.

PURPOSE: U.S. Food and Drug Administration (FDA) recommended telavancin dosing is based on total body weight (TBW) but lacks adjusted regimens for obese subjects with varying renal function. Our aim was to develop a physiologically based pharmacokinetic (PBPK) model of telavancin to design optimized dosing regimens for obese patients with hospital-acquired pneumonia (HAP) and varying renal function. METHODS: The PBPK model was verified using clinical pharmacokinetic (PK) data of telavancin in healthy populations with varying renal function and obese populations with normal renal function. Then, the PBPK model was applied to predict the PK in obese HAP patients with renal impairment (RI). RESULTS: The fold error values of PK parameters (AUC, Cmax, Tmax) were all within 1.5. The telavancin AUC0-inf was predicted to increase 1.07-fold in mild RI, 1.23-fold in moderate RI, 1.41-fold in severe RI, and 1.57-fold in end-stage renal disease (ESRD), compared with that in obese HAP with normal renal function. The PBPK model combined with Monte Carlo simulations (MCS) suggested that dose adjustment based on a 750-mg-fixed dose could achieve effectiveness with reduced risk of toxicity, compared with current TBW-based dosing recommendations. CONCLUSION: The PBPK simulation proposed that using TBW-based regimen in obesity with RI should be avoided. Dose recommendations in obesity from the PBPK model are 750 mg daily for normal renal function and mild RI, 610 mg daily for moderate RI, 530 mg daily for severe RI, and 480 mg daily for ESRD.

Molecular basis of ligand recognition and transport by glucose transporters.

The major facilitator superfamily glucose transporters, exemplified by human GLUT1-4, have been central to the study of solute transport. Using lipidic cubic phase crystallization and microfocus X-ray diffraction, we determined the structure of human GLUT3 in complex with D-glucose at 1.5 Å resolution in an outward-occluded conformation. The high-resolution structure allows discrimination of both α- and ß-anomers of D-glucose. Two additional structures of GLUT3 bound to the exofacial inhibitor maltose were obtained at 2.6 Å in the outward-open and 2.4 Å in the outward-occluded states. In all three structures, the ligands are predominantly coordinated by polar residues from the carboxy terminal domain. Conformational transition from outward-open to outward-occluded entails a prominent local rearrangement of the extracellular part of transmembrane segment TM7. Comparison of the outward-facing GLUT3 structures with the inward-open GLUT1 provides insights into the alternating access cycle for GLUTs, whereby the C-terminal domain provides the primary substrate-binding site and the amino-terminal domain undergoes rigid-body rotation with respect to the C-terminal domain. Our studies provide an important framework for the mechanistic and kinetic understanding of GLUTs and shed light on structure-guided ligand design.

The effects of extreme temperatures on emergency room visits-a population-based analysis by age, sex, and comorbidity.

This study evaluated the effect of extreme temperatures on events requiring emergency room visits (ERVs) for hypertensive disease, ischemic heart disease (IHD), cerebrovascular disease, and chronic kidney disease (CKD) for population stratified by sex and age living in Taiwan's metropolitan city from 2000 to 2014. The distributed lag non-linear model was adopted to examine the association between ambient temperature and area-age-sex-disease-specific ERVs for a population aged 40 years and above. The reference temperature was defined by a percentile value to describe the temperature in each city. Area-age-sex-disease-specific relative risk (RR) and 95% confidence intervals (CI) were estimated in association with extreme high (99th percentile) and low (5th percentile) temperatures. Temperature-related ERV risks varied by area, age, sex, and disease. Patients with CKD tend to have comorbidities with hypertensive disease. All study populations with hypertensive disease have significant risk associations with extreme low temperatures with the highest RR of 2.64 (95% CI: 2.08, 3.36) appearing in New Taipei City. The risk of IHD was significantly associated with extreme high temperature for male subpopulation aged 40-64 years. A less significant association was observed between the risks of cerebrovascular disease with extreme temperature. The risk of CKD was most significantly associated with extreme high temperature especially for a subpopulation aged 40-64 years. All study subpopulations with hypertensive disease have significant risk associations with extreme low temperature. Male subpopulations were more vulnerable to extreme temperatures, especially for those aged 40-64 years.

Midecamycin Is Inactivated by Several Different Sugar Moieties at Its Inactivation Site.

Glycosylation inactivation is one of the important macrolide resistance mechanisms. The accumulated evidences attributed glycosylation inactivation to a glucosylation modification at the inactivation sites of macrolides. Whether other glycosylation modifications lead to macrolides inactivation is unclear. Herein, we demonstrated that varied glycosylation modifications could cause inactivation of midecamycin, a 16-membered macrolide antibiotic used clinically and agriculturally. Specifically, an actinomycetic glycosyltransferase (GT) OleD was selected for its glycodiversification capacity towards midecamycin. OleD was demonstrated to recognize UDP-D-glucose, UDP-D-xylose, UDP-galactose, UDP-rhamnose and UDP-N-acetylglucosamine to yield corresponding midecamycin 2'-O-glycosides, most of which displayed low yields. Protein engineering of OleD was thus performed to improve its conversions towards sugar donors. Q327F was the most favorable variant with seven times the conversion enhancement towards UDP-N-acetylglucosamine. Likewise, Q327A exhibited 30% conversion enhancement towards UDP-D-xylose. Potent biocatalysts for midecamycin glycosylation were thus obtained through protein engineering. Wild OleD, Q327F and Q327A were used as biocatalysts for scale-up preparation of midecamycin 2'-O-glucopyranoside, midecamycin 2'-O-GlcNAc and midecamycin 2'-O-xylopyranoside. In contrast to midecamycin, these midecamycin 2'-O-glycosides displayed no antimicrobial activities. These evidences suggested that besides glucosylation, other glycosylation patterns also could inactivate midecamycin, providing a new inactivation mechanism for midecamycin resistance. Cumulatively, glycosylation inactivation of midecamycin was independent of the type of attached sugar moieties at its inactivation site.

Process Development and Synthesis of Process-Related Impurities of an Efficient Scale-Up Preparation of 5,2'-Dibromo-2,4',5'-Trihydroxy Diphenylmethanone as a New Acute Pyelonephritis Candidate Drug.

Based on a foregoing gram-scale laboratory process, an efficient scale-up preparation process of 5,2'-dibromo-2,4',5'-trihydroxydiphenylmethanone (LM49-API), a new acute pyelonephritis candidate drug, was developed and validated aiming to reduce by-products and achieve better impurity profiles. Meanwhile, the polymorph of LM49-API and process-related impurities were also investigated. Ultimately, the optimal reaction conditions were verified by evaluating the impurity profiles and their formation during the synthesis. Six process-related impurities were synthesized and identified, being useful for the quality control of LM49-API. Its finalized preparation process was further validated at 329-410 g scale-up production in 53.4-57.1% overall yield with 99.95-99.98% high-performance liquid chromatography (HPLC) purity, and it is currently viable for commercial production. LM49-API-imC and LM49-API-imX were identified as the main single impurities in LM49-API, with the content controlled to be less than 0.03%.

Simulation of the Pharmacokinetics of Oseltamivir and Its Active Metabolite in Normal Populations and Patients with Hepatic Cirrhosis Using Physiologically Based Pharmacokinetic Modeling.

Oseltamivir is a neuraminidase inhibitor widely used to treat and prevent influenza A and B infections, although its safety and pharmacokinetics have not been evaluated in patients with severe hepatic impairment. A physiologically based pharmacokinetic (PBPK) model of the prodrug oseltamivir and its active metabolite, oseltamivir carboxylate (OC), was established and validated to simulate their disposition in adults and predict the exposure in patients with Child-Pugh C cirrhosis (CP-C). The simulated results from PBPK modeling and the observed data after oral administration of various oseltamivir regimens were consistent according to the fold error values of less than 2. Furthermore, the clinical observations published in the literature were comparable with our pharmacokinetic predictions. In patients with CP-C, the oseltamivir Cmax was approximately 2-fold increased, and its AUC was approximately 6-fold higher compared with those in normal subjects. In contrast, the AUC of OC in CP-C patients did not differ significantly from that in normal subjects, whereas its Cmax was reduced by approximately 30% in the patients. Examination of drug exposure in different health conditions indicated that the oseltamivir exposure was significantly increased in conditions with elevated cirrhosis severity, which might be associated with a higher risk of adverse drug effects, e.g., neuropsychiatric adverse events (NPAEs). In conclusion, the pharmacokinetics of oseltamivir and OC were correctly predicted by PBPK modeling. The model further predicted that the pharmacokinetics of oseltamivir might be altered in liver cirrhosis, depending on the degree of severity.

Crystal structure of the bacterial acetate transporter SatP reveals that it forms a hexameric channel.

Acetate is found ubiquitously in the natural environment and can be used as an exogenous carbon source by bacteria, fungi, and mammalian cells. A representative member of the acetate uptake transporter (AceTr) family named SatP (also yaaH) has been preliminarily identified as a succinate-acetate/proton symporter in Escherichia coli However, the molecular mechanism of acetate uptake by SatP still remains elusive. Here, we report the crystal structure of SatP from E. coli at 2.8 Å resolution, determined with a molecular replacement approach using a previously developed predicted model algorithm, which revealed a hexameric UreI-like channel structure. Structural analysis identified six transmembrane (TM) helices surrounding the central channel pore in each protomer and three conserved hydrophobic residues, FLY, located in the middle of the TM region for pore constriction. According to single-channel conductance recordings, performed with purified SatP reconstituted into lipid bilayer, three conserved polar residues in the TM1 facing to the periplasmic side are closely associated with acetate translocation activity. These analyses provide critical insights into the mechanism of acetate translocation in bacteria and a first glimpse of a structure of an AceTr family transporter.

Serum GP73 predicts posthepatectomy outcomes in patients with hepatocellular carcinoma.

BACKGROUND AND AIMS: Serum GP73 is a useful biomarker in assessing hepatic fibrosis degree. The aim of this study was to evaluate the predictive value of serum GP73 level for posthepatectomy short-term outcomes in hepatocellular carcinoma (HCC) patients. METHODS: A total of 280 patients undergoing liver resection for HCC between October 2015 and April 2018 were included in this study. Detailed preoperative clinicopathological data were collected and GP73 levels in serum obtained the day before hepatectomy were examined. Receiver operating characteristic (ROC) analysis was used to calculate the optimal cutoff of GP73, and independent risk factors for postoperative outcomes was assessed by logistic regression model. RESULTS: The mean GP73 level in patients was 111.8 ± 153.3 ng/mL. Serum GP73 levels were correlated with the METAVIR fibrosis score. Overall complications occurred in 145 patients and major complications developed in 29 patients. ROC analysis demonstrated that the predictive power of serum GP73 for postoperative outcomes was greater than the Child-Pugh score, ALBI score, FIB-4 index and APRI score. The optimal value of serum GP73 to predict overall complications and major complications was 80.9 and 79.2 respectively. Serum GP73 levels were independent factors affecting the incidence of overall complications (odds ratio [OR], 3.996; 95% CI 2.152-7.421; P < 0.001) and major complications (OR, 4.970; 95% CI 1.654-14.934; P = 0.004) by multivariate analysis. CONCLUSION: Serum GP73 is a useful tool to stratify HCC patients and to predict short-term outcomes after hepatectomy.

Crystal structure of a LacY-nanobody complex in a periplasmic-open conformation.

The lactose permease of Escherichia coli (LacY), a dynamic polytopic membrane protein, catalyzes galactoside-H+ symport and operates by an alternating access mechanism that exhibits multiple conformations, the distribution of which is altered by sugar binding. We have developed single-domain camelid nanobodies (Nbs) against a mutant in an outward (periplasmic)-open conformation to stabilize this state of the protein. Here we describe an X-ray crystal structure of a complex between a double-Trp mutant (Gly46→Trp/Gly262→Trp) and an Nb in which free access to the sugar-binding site from the periplasmic cavity is observed. The structure confirms biochemical data indicating that the Nb binds stoichiometrically with nanomolar affinity to the periplasmic face of LacY primarily to the C-terminal six-helix bundle. The structure is novel because the pathway to the sugar-binding site is constricted and the central cavity containing the galactoside-binding site is empty. Although Phe27 narrows the periplasmic cavity, sugar is freely accessible to the binding site. Remarkably, the side chains directly involved in binding galactosides remain in the same position in the absence or presence of bound sugar.

Molecular determinants for the thermodynamic and functional divergence of uniporter GLUT1 and proton symporter XylE.

GLUT1 facilitates the down-gradient translocation of D-glucose across cell membrane in mammals. XylE, an Escherichia coli homolog of GLUT1, utilizes proton gradient as an energy source to drive uphill D-xylose transport. Previous studies of XylE and GLUT1 suggest that the variation between an acidic residue (Asp27 in XylE) and a neutral one (Asn29 in GLUT1) is a key element for their mechanistic divergence. In this work, we combined computational and biochemical approaches to investigate the mechanism of proton coupling by XylE and the functional divergence between GLUT1 and XylE. Using molecular dynamics simulations, we evaluated the free energy profiles of the transition between inward- and outward-facing conformations for the apo proteins. Our results revealed the correlation between the protonation state and conformational preference in XylE, which is supported by the crystal structures. In addition, our simulations suggested a thermodynamic difference between XylE and GLUT1 that cannot be explained by the single residue variation at the protonation site. To understand the molecular basis, we applied Bayesian network models to analyze the alteration in the architecture of the hydrogen bond networks during conformational transition. The models and subsequent experimental validation suggest that multiple residue substitutions are required to produce the thermodynamic and functional distinction between XylE and GLUT1. Despite the lack of simulation studies with substrates, these computational and biochemical characterizations provide unprecedented insight into the mechanistic difference between proton symporters and uniporters.

Gamma-glutamyl transpeptidase to platelet ratio predicts short-term outcomes in hepatocellular carcinoma patients undergoing minor liver resection.

BACKGROUND: There is a strong correlation between liver fibrosis and postoperative morbidity after hepatectomy in hepatocellular carcinoma (HCC) patients. The aim of this study was to evaluate which noninvasive fibrosis index (gamma-glutamyl transpeptidase to platelet ratio [GPR], aspartate aminotransferase to platelet ratio index, fibrosis-4 index, or Forns index) was best able to predict complications in patients undergoing hepatectomy for HCC. MATERIALS AND METHODS: This retrospective analysis included 275 patients who underwent hepatectomy for HCC from January 2008 to December 2012. Postoperative mortality was defined as death within 90 d after surgery. Complications were grouped into seven grades on the basis of the modified Clavien classification, and major postoperative complications were defined as grade 3 or above. The influence of noninvasive fibrosis indices on postoperative outcomes was assessed by receiver operating characteristic analysis. The primary outcomes were overall complications and major complications, estimated by univariate and multivariate analysis. RESULTS: Patients with HCC undergoing anatomical liver resection in the authors' department were evaluated for this study. Finally, 275 patients who underwent minor liver resection (≤2 liver segments) were included. Of these, 231 (84%) were male. The multivariate analysis indicated that the GPR index was not only independently associated with overall complications (hazard ratio, 2.692; 95% confidence interval [CI], 1.626-4.250; P < 0.001) but also independently predictive of major complications (hazard ratio, 1.143; 95% CI, 1.046-1.249; P = 0.03). The areas under the receiver operating characteristic curve for predicting overall complications and major complications for the GPR index were 0.704 (95% CI, 0.643-0.765; P < 0.001) and 0.752 (95% CI, 0.638-0.865; P < 0.001), respectively. CONCLUSIONS: The data suggested that the GPR index could be a promising predictor of overall postoperative complications and major complications after minor hepatectomy for HCC.

Sliding Spotlight Mode Imaging with GF-3 Spaceborne SAR Sensor.

Synthetic aperture radar (SAR) sliding spotlight work mode can achieve high resolutions and wide swath (HRWS) simultaneously by steering the radar antenna beam. This paper aims to obtain well focused images using sliding spotlight mode with the Chinese Gaofen-3 SAR sensor. We proposed an integrated imaging scheme with sliding spotlight echoes. In the imaging scheme, the two-step approach is applied to the spaceborne sliding spotlight SAR imaging algorithm, followed by the Doppler parameter estimation algorithm. The azimuth spectral folding phenomenon is overcome by the two-step approach. The results demonstrate a high Doppler parameter estimation accuracy. The proposed imaging process is accurate and highly efficient for sliding spotlight SAR mode.