[Association between congenital hypothyroidism and in-hospital adverse outcomes in very low birth weight infants]

Objective: To investigate the association between congenital hypothyroidism (CH) and the adverse outcomes during hospitalization in very low birth weight infants (VLBWI). Methods: This prospective, multicenter observational cohort study was conducted based on the data from the Sino-northern Neonatal Network (SNN). Data of 5 818 VLBWI with birth weight <1 500 g and gestational age between 24-<37 weeks that were admitted to the 37 neonatal intensive care units from January 1st, 2019 to December 31st, 2022 were collected and analyzed. Thyroid function was first screened at 7 to 10 days after birth, followed by weekly tests within the first 4 weeks, and retested at 36 weeks of corrected gestational age or before discharge. The VLBWI were assigned to the CH group or non-CH group. Chi-square test, Fisher exact probability method, Wilcoxon rank sum test, univariate and multivariate Logistic regression were used to analyze the relationship between CH and poor prognosis during hospitalization in VLBWI. Results: A total of 5 818 eligible VLBWI were enrolled, with 2 982 (51.3%) males and the gestational age of 30 (29, 31) weeks. The incidence of CH was 5.5% (319 VLBWI). Among the CH group, only 121 VLBWI (37.9%) were diagnosed at the first screening. Univariate Logistic regression analysis showed that CH was associated with increased incidence of extrauterine growth retardation (EUGR) (OR=1.31(1.04-1.64), P<0.05) and retinopathy of prematurity (ROP) of stage Ⅲ and above (OR=1.74(1.11-2.75), P<0.05). However, multivariate Logistic regression analysis showed no significant correlation between CH and EUGR, moderate to severe bronchopulmonary dysplasia, grade Ⅲ to Ⅳ intraventricular hemorrhage, neonatal necrotizing enterocolitis in stage Ⅱ or above, and ROP in stage Ⅲ or above (OR=1.04 (0.81-1.33), 0.79 (0.54-1.15), 1.15 (0.58-2.26), 1.43 (0.81-2.53), 1.12 (0.70-1.80), all P>0.05). Conclusion: There is no significant correlation between CH and in-hospital adverse outcomes, possibly due to timely diagnosis and active replacement therapy.

[Optic atrophy in a patient with axonal Charcot-Marie-Tooth disease 2A2A due to MFN2 gene mutations]

A 27-year-old male patient had progressive vision loss in both eyes, which was mainly manifested by impaired ganglion cells in the macular area, accompanied by systemic muscle atrophy in limbs. A complete mitochondrial exon gene detection was performed. The final diagnosis was bilateral optic atrophy and axonal Charcot-Marie-Tooth disease 2A2A caused by mutations of the MFN2 gene. There has been no effective treatment. Applications of nutrients to restore the mitochondrial function may alleviate the clinical symptoms.

[Analysis of clinicopathological characteristics of non-alcoholic fatty liver disease]

Objective: To investigate the clinical and pathologic characteristics of obese adults with nonalcoholic fatty liver disease (NAFLD) and to aid the diagnosis of nonalcoholic steatohepatitis (NASH). Methods: A total of 262 patients eligible for inclusion who received volume reduction metabolism surgery and liver biopsy in the First Affiliated Hospital of Nanjing Medical University from June 2018 to September 2019 were selected. HE staining, reticular fiber staining and Masson staining were performed. Statistical analysis was performed using SPSS 20.0. Results: The patients ranged in age from 18 to 66 years. Among the 262 cases, 65 cases (65/262, 24.8%) were male and 197 cases (197/262, 75.2%) were female. Sixty-one cases (61/262, 23.3%) were non-NAFLD, 201 cases (201/262, 76.7%) were NAFLD including 27 cases (27/201, 13.4%) of nonalcoholic fatty live (NAFL) and 174 cases (174/201, 86.6%) of NASH. The main lesions of NAFLD were in hepatic acinus zone 3. There were significant differences in age, alanine aminotransferase (ALT), glutamic oxaloacetic transaminase (AST), body mass index (BMI), fasting blood-glucose (FPG) and apolipoprotein A (APOA) levels among the non-NAFLD group, NAFL group and NASH group (P<0.05). Patients with BMI≥35 m/kg² combined with type 2 diabetes had a higher prevalence of NASH. Multiple logistic regression showed that ALT and APOA were independent predictors of NASH (P<0.001, OR=1.05, 95%CI: 1.020-1.082; P=0.027, OR=0.916, 95%CI: 0.878-0.941). Total cholesterol (CHO) and high-density lipoprotein (HDL) were independent predictors of lobular inflammation (P=0.043, 95%CI: 0.010-0.634; P=0.024, 95%CI:-3.068--0.216). AST and HDL were independent predictors of fibrosis stage (P=0.029, 95%CI: 0.001-0.021; P<0.001, 95%CI:-2.670--0.645). Conclusions: Biochemical indicators of NAFLD are closely related to its pathology. The histological lesions of NAFLD are mainly present in hepatic acinar area 3. The diagnosis of NASH is supported by extensive steatosis and high levels of CHO, ALT, AST and BMI, low levels of HDL and ApoA in biochemical markers, but pathological examination is still the gold standard for it.

Randomised controlled trial: effect of metformin add-on therapy on functional cure in entecavir-treated patients with chronic hepatitis B

INTRODUCTION AND OBJECTIVES

Hepatitis B surface antigen (HBsAg) clearance, indicating functional cure or resolved chronic hepatitis B (CHB), remains difficult to achieve via nucleos(t)ide analogue monotherapy. We investigated whether metformin add-on therapy could help achieve this goal in entecavir-treated patients with hepatitis B e antigen (HBeAg)-negative CHB.

PATIENTS AND METHODS

Patients with HBeAg-negative CHB who met eligibility criteria (entecavir treatment for &gt; 12 months, HBsAg &lt; 1000 IU/mL) were randomly assigned (1:1) to receive 24 weeks of either metformin (1000 mg, oral, once a day) or placebo (oral, once a day) add-on therapy. The group allocation was blinded for both patients and investigators. Efficacy and safety analyses were based on the intention-to-treat set. The primary outcome, serum HBsAg level (IU/mL) at weeks 24 and 36, was analysed using mixed models.

RESULTS

Sixty eligible patients were randomly assigned to the metformin (n = 29) and placebo (n = 31) groups. There was no substantial between-group difference in the HBsAg level at week 24 (adjusted mean difference 0.05, 95% confidence interval -0.04 to 0.13, p = 0.278) or week 36 (0.06, -0.03 to 0.15, p = 0.187), and no significant effect of group-by-time interaction on the HBsAg level throughout the trial (p = 0.814). The occurrence of total adverse events between the two groups was comparable (9 [31.0%] of 29 vs. 5 [16.1%] of 31, p = 0.227) and no patient experienced serious adverse events during the study.

CONCLUSION

Although it was safe, metformin add-on therapy did not accelerate HBsAg clearance in entecavir-treated patients with HBeAg-negative CHB.

[Myelin oligodendrocyte glycoprotein antibody positive optic neuritis with anti-N-methyl-D-aspartate receptor encephalitis: a case report]

A 6-year-old girl had binocular vision loss with pain for one week. The patient presented with symptoms such as non-communication, language deterioration, dysphonia, and choking when drinking and eating during the course. The serum myelin oligodendrocyte glycoprotein antibody was positive. Both the serum and cerebrospinal fluid anti-N-methyl-D-aspartate receptor antibody were also positive. The diagnoses were myelin oligodendrocyte glycoprotein antibody positive optic neuritis and anti-N-methyl-D-aspartate receptor encephalitis. High-dose intravenous glucocorticoids were given. Recurrence was not observed during the 15-month clinical follow-up.

[Changes of immunohistochemical biomarkers before and after neoadjuvant chemotherapy in breast cancer and their prognosis]

Objective: To investigate changes in the expression of immunohistochemical (IHC) markers and factors associated with the effect of chemotherapy before and after neoadjuvant chemotherapy (NAC). Methods: A retrospective study included 200 breast cancer patients treated with NAC between January 2016 and December 2018. We analyzed the changes in the expression of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and Ki-67 in pre- and post-treated samples and the predictive factors of NAC. Results: Among the 200 cases, 16 cases were luminal A, 108 cases were luminal B, 36 cases were HER2⁺subtype, and 40 cases were basal-like. Twenty-five patients (12.50%) achieved pathological complete remission (PCR).There were significant differences in PR and Ki-67 before and after NAC but there were no differences in ER and HER2.In univariate analysis, factors associated with PCR were tumor less than 5 cm(P=0.009), non-luminal breast cancer (P=0.001), ER negative(P=0.001), PR negative (P=0.029) and HER2 positive(P=0.001). Tumor less than 5 cm [P=0.020, OR=2.581, 95%CI (1.207, 5.753)], ER negative [P=0.011, OR=2.264, 95%CI (1.207, 4.248)] and HER2 positive[P=0.007, OR=2.412, 95%CI (1.275, 4.561)] remained predictive variables in multivariate analysis after correction for the other variables. Conclusions: The expression of Ki-67 decreases after NAC. Negative PR and ER and positive HER2 status are related to the efficacy of pCR for breast cancer, and have guiding significance for the prognosis evaluation of NAC.

The Transcription Factor NIGT1.2 Modulates Both Phosphate Uptake and Nitrate Influx during Phosphate Starvation in Arabidopsis and Maize

Phosphorus and nitrogen are essential macronutrients for plant growth and crop production. During phosphate (Pi) starvation, plants enhanced Pi but reduced nitrate (NO3 -) uptake capacity, and the mechanism is unclear. Here, we show that a GARP-type transcription factor NITRATE-INDUCIBLE, GARP-TYPE TRANSCRIPTIOANL REPRESSOR1.2 (NIGT1.2) coordinately modulates Pi and NO3 - uptake in response to Pi starvation. Overexpression of NIGT1.2 increased Pi uptake capacity but decreased NO3 - uptake capacity in Arabidopsis (Arabidopsis thaliana). Furthermore, the nigt1.1 nigt1.2 double mutant displayed reduced Pi uptake but enhanced NO3 - uptake under low-Pi stress. During Pi starvation, NIGT1.2 directly up-regulated the transcription of the Pi transporter genes PHOSPHATE TRANSPORTER1;1 (PHT1;1) and PHOSPHATE TRANSPORTER1;4 (PHT1;4) and down-regulated expression of NO3 - transporter gene NITRATE TRANSPORTER1.1 (NRT1.1) by binding to cis-elements in their promoters. Further genetic assays demonstrated that PHT1;1, PHT1;4, and NRT1.1 were genetically epistatic to NIGT1.2 We also identified similar regulatory pathway in maize (Zea mays). These data demonstrate that the transcription factor NIGT1.2 plays a central role in modulating low-Pi-dependent uptake of Pi and NO3 -, tending toward maintenance of the phosphorus to nitrogen balance in plants during Pi starvation.

Serum N-glycan markers for diagnosing liver fibrosis induced by hepatitis B virus

BACKGROUND

Hepatitis B virus (HBV) infection is the primary cause of hepatitis with chronic HBV infection, which may develop into liver fibrosis, cirrhosis and hepatocellular carcinoma. Detection of early-stage fibrosis related to HBV infection is of great clinical significance to block the progression of liver lesion. Direct liver biopsy is regarded as the gold standard to detect and assess fibrosis; however, this method is invasive and prone to clinical sampling error. In order to address these issues, we attempted to find more convenient and effective serum markers for detecting HBV-induced early-stage liver fibrosis.

AIM

To investigate serum N-glycan profiling related to HBV-induced liver fibrosis and verify multiparameter diagnostic models related to serum N-glycan changes.

METHODS

N-glycan profiles from the sera of 432 HBV-infected patients with liver fibrosis were analyzed. Significant changed N-glycan levels (peaks) (P < 0.05) in different fibrosis stages were selected in the modeling group, and multiparameter diagnostic models were established based on changed N-glycan levels by logistic regression analysis. The receiver operating characteristic (ROC) curve analysis was performed to evaluate diagnostic efficacy of N-glycans models. These models were then compared with the aspartate aminotransferase to platelet ratio index (APRI) , fibrosis index based on the four factors (FIB-4), glutamyltranspeptidase platelet albumin index (S index), GlycoCirrho-test, and GlycoFibro-test. Furthermore, we combined multiparameter diagnostic models with alanine aminotransferase (ALT) and platelet (PLT) tests and compared their diagnostic power. In addition, the diagnostic accuracy of N-glycan models was also verified in the validation group of patients.

RESULTS

Multiparameter diagnostic models constructed based on N-glycan peak 1, 3, 4 and 8 could distinguish between different stages of liver fibrosis. The area under ROC curves (AUROCs) of Model A and Model B were 0.890 and 0.752, respectively differentiating fibrosis F0-F1 from F2-F4, and F0-F2 from F3-F4, and surpassing other serum panels. However, AUROC (0.747) in Model C used for the diagnosis of F4 from F0-F3 was lower than AUROC (0.795) in FIB-4. In combination with ALT and PLT, the multiparameter models showed better diagnostic power (AUROC = 0.912, 0.829, 0.885, respectively) when compared with other models. In the validation group, the AUROCs of the three combined models (0.929, 0.858, and 0.867, respectively) were still satisfactory. We also applied the combined models to distinguish adjacent fibrosis stages of 432 patients (F0-F1/F2/F3/F4), and the AUROCs were 0.917, 0.720 and 0.785.

CONCLUSION

Multiparameter models based on serum N-glycans are effective supplementary markers to distinguish between adjacent fibrosis stages of patients caused by HBV, especially in combination with ALT and PLT.

Effect of RhoC silencing on multiple myeloma xenografts and angiogenesis in nude mice

In this study, we investigated the expression of RhoC in the multiple myeloma (MM) cell line RPMI- 8226, as well as the effects of silencing RhoC on the growth of tumor xenografts and tumor-induced angiogenesis in nude mice with MM. For this purpose, we transduced RPMI-8226 cells with lentiviral particles overexpressing short hairpin RNAs (shRNA) targeting RhoC. Tumor xenografts were generated by subcutaneously injecting nude mice with RPMI-8226 cells overexpressing control shRNA [negative control (NC) group] or the RhoC shRNA [the experimental (S) group], respectively. RhoC protein and mRNA levels in the tumor xenografts were measured. Nude mice were also subcutaneously inoculated with Matrigel mixed with vascular endothelial growth factor, and CD31 and KI67 levels in the tumor xenografts were measured by immunohistochemistry. Similarly, we assessed tumor xenograft growth and angiogenesis in Matrigel implants in the mice of both groups. We found that RhoC levels, microvessel density, and CD31 labeling index were more reduced in the S group than in the NC group. However, there was no significant difference in the size of tumor xenografts between the 2 groups. The number of new vessels and the neovascular length in the Matrigel implants were significantly lower in the S group than in the NC group. Therefore, we concluded that RhoC expression in myeloma xenografts has important effects on the induction of angiogenesis.

[HER2 status in gastric adenocarcinoma of Chinese: a multicenter study of 40 842 patients]

Objective: To investigation HER2 status in gastric adenocarcinoma of Chinese and contributing factors to the HER2 expression. Methods: HER2 status of 40 842 gastric adenocarcinomas and clinical data were retrospectively collected from 23 hospitals dated from 2013 to 2016. The association between HER2 positivity and clinicopathologic features was analyzed. Results: Of the 40 842 patients the median age was 62 years, the male female ratio was 2.6∶1.0. The rate of HER2 positivity was 8.8% (3 577/40 842). HER2 expression was related to the tissue type, tumor location, Lauren classification and tumor differentiation (P values: 0.009, 0.001, <0.01 and <0.01, respectively). Different HER2 expression status was observed between primary and recurrent tumors in 7.6% (48/635) cases. The rates of HER2 positivity ranged from 2% to 10% among different institutions. The rates of HER2 FISH amplification were dramatically different among the 23 hospitals (0-100%) with an average rate of 10% (810/8 156) in patients with HER2 IHC 2+ . Conclusions: HER2 expression is associated with clinicopathologic characteristics. HER2 re-assessment of tumor tissue and use of in situ hybridization techniques increase HER2 positivity. The current retrospective study should reflect the HER2 status in gastric adenocarcinoma of Chinese patients.

[Predictive value of liver pathologic changes in determining the effectiveness of entecavir treatment for chronic hepatitis B-An analysis of 1 366 cases]

Objective: To analyze the relationship between baseline liver pathologic changes and the effectiveness of entecavir(ETV) and investigate the predictive value of baseline liver pathologic changes in determining the effectiveness of ETV, to provide reliable basis for precision medicine in patients with chronic hepatitis B(CHB). Methods: A total of 1 366 cases with CHB were retrospectively recruited who underwent liver biopsy between January 2006 to June 2016 and were treated with ETV over 96 weeks.The relationship between baseline liver pathologic changes and the antiviral responses to ETV at 48, 96 weeks were compared. Results: Liver pathology was employed to make the definite inflammation grade and the fibrosis stage.According to the liver inflammation and fibrosis, patients were divided into 4 groups(G1, G2, G3, G4 and S1, S2, S3, S4 respectively). The complete response rate of G1, G2, G3 and G4 after 48 weeks ETV treatment was 26.3%(10/38), 30.9%(121/391), 35.3%(101/286), 44.4%(52/117) respectively in HBeAg positive patients and was 61.5%(24/39), 80.4%(148/184), 82.4%(201/244), 88.1%(59/67) respectively in HBeAg negative patients.There was statistical difference in the complete response rates among liver inflammation grades both in HBeAg positive patients(χ(2)=8.510, P<0.05) and in HBeAg negative patients(χ(2)=12.054, P<0.05)respectively.The differences were still statistical significant after 96 weeks ETV treatment (P<0.05). The complete response rates of S1, S2, S3 and S4 after 48 weeks ETV treatment were 39.0%(41/105), 37.8%(127/336), 30.9%(97/314), 24.7%(19/77), respectively in HBeAg positive patients and was 85.7%(30/35), 84.4%(92/109), 83.9%(162/193), 75.1%(148/197) respectively in HBeAg negative patients. Whether HBeAg was positive or not, the rates were in decline but there was no statistical difference in the complete response rates among liver fibrosis stages(χ(2)=7.765, P>0.05; χ(2)=6.729, P>0.05). The differences were still not statistical significant after 96 weeks ETV treatment (P>0.05). But after further grouping, whether HBeAg was positive or not, as the degree of fibrosis stage was aggravating, the complete response rate of G2, G3 and G4 after 48 weeks ETV treatment decreased at the same degree of inflammation grade and the differences were statistically significant (P<0.05). The differences were still statistical significant after 96 weeks ETV treatment (P<0.05). Conclusions: The responses to ETV treatment are closely related with baseline liver pathology.The CHB patients with higher score of inflammation and lower score of fibrosis will have a good response to ETV treatment.The degree of inflammation grades and fibrosis stages can be used as early predictors of ETV treatment for CHB.

Effects of tumor-associated macrophages on the proliferation and migration of esophageal cancer-associated lymphatic endothelial cells

The aim of this study was to explore whether M2 macrophages can be transformed into M1 macrophages, and to investigate the effect of different types of macrophages on the proliferation, migration and ring-forming ability of esophageal cancer-related lymphatic endothelial cell (LEC). Human monocytic leukemia cell line (THP-1 cell) was induced to differentiate to M1 macrophages (M1 group) and M2 macrophages (M2 group), and co-cultured with esophageal cancer-associated LEC. The individual esophageal cancer co-cultured with LEC was used as control. Different types of macrophages were observed by Cell counting kit-8 (CCK-8). Enzyme-linked immunosorbent assay (ELISA) was used to detect the VEGF-C concentration; the expression of VEGFR-3 protein and its mRNA was detected by Western blot and qRT-PCR, respectively. The positive rate of the M1 group induced by IFN-γ and LPS was significantly higher than that of M2 macrophages (48.57%5.98% vs 25.83%1.95%). The expression of VEGF-C in the supernatant of the M2 group was higher than that in the control group, but no significant differences regarding the expression of VEGF-C between M1 and control groups were found. In addition, the expression of VEGFR-3 on both mRNA and protein in esophageal cancer-related LEC of the M2 group was significantly higher than those in the control group; however, the M1 group had a significantly lower VEGFR-3 level on both mRNA and protein than the control group. Human M2 macrophages can be transformed into M1 macrophages, and can promote the proliferation, migration and ring-forming ability of esophageal cancer-associated LEC.

Abscisic Acid Modulates Seed Germination via ABA INSENSITIVE5-Mediated PHOSPHATE1

The phytohormone abscisic acid (ABA) controls many developmental and physiological processes. Here, we report that PHOSPHATE1 (PHO1) participates in ABA-mediated seed germination and early seedling development. The transcription of PHO1 was obviously enhanced during seed germination and early seedling development and repressed by exogenous ABA. The pho1 mutants (pho1-2, pho1-4, and pho1-5) showed ABA-hypersensitive phenotypes, whereas the PHO1-overexpressing lines were ABA-insensitive during seed germination and early seedling development. The expression of PHO1 was repressed in the ABI5-overexpressing line and elevated in the abi5 mutant, and ABI5 can bind to the PHO1 promoter in vitro and in vivo, indicating that ABI5 directly down-regulated PHO1 expression. Disruption of PHO1 abolished the ABA-insensitive germination phenotypes of abi5 mutant, demonstrating that PHO1 was epistatic to ABI5 Together, these data demonstrate that PHO1 is involved in ABA-mediated seed germination and early seedling development and transcriptionally regulated by ABI5.

BLCA-4 and UBC combined detection for early diagnosis of bladder cancer

The objective of the present study was to report the clinical significance of bladder cancer specific nuclear matrix protein 4 (BLCA-4) and urinary bladder cancer (UBC) on early diagnosis of bladder cancers. Enzyme-linked immunosorbent assay (ELISA) was used to detect BLCA-4 and UBC of 56 bladder cancer patients and 26 patients with urinary tract benign diseases, serving as controls. Urine exfoliated cell test was performed, and then the significance of BLCA-4 and UBC on the diagnosis of bladder cancers was analyzed. The sensitivity of BLCA-4 and UBC of the bladder cancer patients was significantly higher than that of the urine exfoliated cell test (P less than 0.05). The difference of BLCA-4 and UBC was not significant (P >0.05). The difference of BLCA-4 and UBC in the tumors with different gradings and stagings was not significant (P >0.05). Combined detection of BLCA-4 and UBC could improve the diagnosis sensitivity and specificity of bladder cancers with the advantages of high maneuverability, repeatability and objective results.

Effect of PTEN antisense oligonucleotide on oesophageal squamous cell carcinoma cell lines

OBJECTIVE

To investigate the effects of a phosphatase and tensin homologue (PTEN) antisense oligonucleotide on PTEN and mammalian target of rapamycin (mTOR) mRNA and protein, cell proliferation and apoptosis in oesophageal squamous cell carcinoma (OCSS) cell lines.

METHODS

EC9706 and EC1 cells were transfected with PTEN antisense oligonucleotide, sense oligonucleotide or nonsense oligonucleotide. Cell proliferation and apoptosis were quantified. Immuno cyto chemistry and in situ hybridization were used to determine PTEN and mTOR protein and mRNA levels, respectively.

RESULTS

Transfection with PTEN antisense oligonucleotide dose- and time-dependently enhanced cell proliferation and inhibited apoptosis in both EC9706 and EC1 cells. PTEN mRNA and protein were significantly downregulated, and mTOR protein and mRNA were significantly upregulated.

CONCLUSION

These data suggest that PTEN is an important tumour suppressor gene in the development of OSCC.

Mechanistic target of rapamycin small interfering RNA and rapamycin synergistically inhibit tumour growth in a mouse xenograft model of human oesophageal carcinoma

OBJECTIVES

To investigate the effect of mechanistic target of rapamycin (mTOR)-specific small interfering RNA (siRNA) and rapamycin on tumour size and levels of hypoxia inducible factor 1α(HIF-1α), vascular endothelial growth factor (VEGF) and mTOR proteins, and mTOR mRNA, in a mouse xenograft model of human oesophageal carcinoma.

METHODS

Tumours were induced in BALB/c nude mice using the human oesophageal squamous cell carcinoma cell line, EC1, injected subcutaneously. Animals were divided into four treatment groups (n = 5 per group) after 7 days: control (phosphate buffered saline, daily intraperitoneal [i.p.] injection); 50 μg/kg rapamycin, daily i.p. injection; 3 μg/kg mTOR siRNA, daily i.p. injection; combined mTOR siRNA and rapamycin, daily i.p. injections. Tumour volume was measured 21 days after xenograft. Levels of mTOR, VEGF and HIF-1α were assessed via immunohistochemistry and in situ hybridization.

RESULTS

mTOR siRNA and/or rapamycin significantly decreased tumour volume and levels of HIF-1α, VEGF and mTOR protein, and mTOR mRNA. Combination treatment was significantly more effective than either treatment alone.

CONCLUSIONS

mTOR siRNA and/or rapamycin inhibited the growth of oesophageal carcinoma in vivo. This may represent a novel and effective treatment strategy for oesophageal carcinoma.

Mechanism of pressure-induced thermostabilization of proteins: studies of glutamate dehydrogenases from the hyperthermophile Thermococcus litoralis

In this study, we investigated the effect of pressure on protein structure and stability at high temperature. Thermoinactivation experiments at 5 and 500 atm were performed using the wild-type (WT) enzyme and two single mutants (D167T and T138E) of the glutamate dehydrogenase (GDH) from the hyperthermophile Thermococcus litoralis. All three GDHs were stabilized, although to different degrees, by the application of 500 atm. Interestingly, the degree of pressure stabilization correlated with GDH stability as well as the magnitude of electrostatic repulsion created by residues at positions 138 and 167. Thermoinactivation experiments also were performed in the presence of trehalose. Addition of the sugar stabilized all three GDHs; the degree of sugar-induced thermostabilization followed the same order as pressure stabilization. Previous studies suggested a mechanism whereby the enzyme adopts a more compact and rigid structure and volume fluctuations away from the native state are diminished under pressure. The present results on the three GDHs allowed us to further confirm and refine the proposed mechanism for pressure-induced thermostabilization. In particular, we propose that pressure stabilizes against thermoinactivation by shifting the equilibrium between conformational substates of the GDH hexamer, thus inhibiting irreversible aggregation.

Pressure-induced thermostabilization of glutamate dehydrogenase from the hyperthermophile Pyrococcus furiosus

In this paper, elevated pressures up to 750 atm (1 atm = 101 kPa) were found to have a strong stabilizing effect on two extremely thermophilic glutamate dehydrogenases (GDHs): the native enzyme from the hyperthermophile Pyrococcus furiosus (Pf), and a recombinant GDH mutant containing an extra tetrapeptide at the C-terminus (rGDHt). The presence of the tetrapeptide greatly destabilized the recombinant mutant at ambient pressure; however, the destabilizing effect was largely reversed by the application of pressure. Electron spin resonance (ESR) spectroscopy of a spin-label attached to the terminal cysteine of rGDHt revealed a high degree of mobility, suggesting that destabilization is due to weakened intersubunit ion-pair interactions induced by thermal fluctuations of the tetrapeptide. For both enzymes, the stabilizing effect of pressure increased with temperature as well as pressure, reaching 36-fold for rGDHt at 105 degrees C and 750 atm, the largest pressure-induced thermostabilization of an enzyme reported to date. Stabilization of both native GDH and rGDHt was also achieved by adding glycerol. Based on the kinetics of thermal inactivation and the known effects of glycerol on protein structure, a mechanism of pressure-induced thermostabilization is proposed.