Brain tumor protein synthesis and histological grades: A study by positron emission tomography (PET) with C11-L-Methionine

Summary Brain protein synthesis may be evaluated in vivo by a PET three compartment methionine model. 14 human brain tumor patients were studied. Protein synthesis rate (PSR) was increased in any glial tumor even in low grades, but this increase was statistically more important in anaplastic tumor.Radiotherapy action was evaluated in two patients. Local tumoral PSR was reduced to normal brain PSR after treatment. No difference was seen in normal cortex contralateral to the lesion between pre and post radiotherapy examination.11 C-L-Methionine incorporation measured by PET looks as a very sensitive method for studying tumor metabolism and treatment effects.     

MTHFR和MTRR基因多态性与急性脑梗死的关联分析

目的探讨亚甲基四氢叶酸还原酶(MTHFR)、甲硫氨酸合成酶还原酶(MTRR)基因多态性与急性脑梗死(ACI)的关联。方法以130例ACI患者为病例组,130例体检健康者为健康对照组,PCR-荧光探针法对两组人群MTHFR基因677CT、1298AC位点和MTRR基因66AG位点的多态性进行定性检测,分析两组人群的基因型及其分布,酶法检测血清同型半胱氨酸(Hcy)水平。结果与健康对照组比较,ACI组MTHFR 677CT的T等位基因频率、MTRR 66AG的G等位基因频率显著升高(χ~2=21.03,P0.01和χ~2=12.45,P0.01),而MTHFR 1298AC差异无统计学意义(P0.05)。此外,与健康对照组比较,ACI组血清Hcy明显升高(P0.01),血清Hcy水平在MTHFR 677CT、MTHFR 1298AC及MTRR 66AG的基因型间差异具有统计学意义(P0.05)。结论 MTHFR 677 T等位基因、MTRR 66 G等位基因与ACI密切相关,MTHFR 1298AC未发现与ACI相关,3位点SNP均与ACI患者Hcy水平升高有关。     

Nutritional and racial determinants of the increase in plasma homocysteine levels after methionine loading

Background: Low circulating plasma levels of total homocysteine (tHcy) are associated with a lower prevalence of coronary heart disease among black people than among white people living in Burkina Faso.Objective: The purpose of this study was to provide a rationale for a possible mechanism for the decrease in plasma tHcy levels among black people compared with white people living in Burkina Faso.Methods: Healthy, black, adult, lifelong inhabitants of Burkina Faso and healthy, white adults born in Italy but living in Burkina Faso ≥5 years were eligible for enrollment. Controlled diets were assigned to all subjects for 2 weeks before the study. After an overnight (12-hour) fast, a methionine-loading test was performed in all subjects. Plasma levels of tHcy, cysteine, glutathione, and cysteinylglycine were measured simultaneously using high-performance liquid chromatography after fasting (baseline) and at either 4 and 8 hours (n = 30) or 2, 4, 6, and 8 hours (n = 4) after methionine loading. During the 12 hours after loading, the clinical conditions and adverse events of subjects were monitored. Results were analyzed using the Student t test and Mann-Whitney U test.Results: Seventeen black adults (9 males, 8 females; median age, 21 years) and 17 white adults (8 males, 9 females; median age, 35 years) were enrolled. Mean plasma levels of tHcy, cysteine, and glutathione increased from mean baseline levels more slowly in the black group than in the white group and peaked 8 hours after methionine loading (16.8 ± 3.0 μmol/L, 130.4 ± 25.7 μmol/L, and 68.3 ± 21.2 μmol/L, respectively). In the white group, these levels peaked 4 hours after loading (16.1 ± 4.0 μmol/L, 215.8 ± 18.6 μmol/L, and 38.6 ± 12.4 μmol/L, respectively). Only the mean plasma cysteinylglycine level decreased significantly (from 35.7 ± 11.4 μmol/L to 19.0 ± 6.1 μmol/L; P < 0.01) in the black group after 4 hours. This decrease was followed by an increase after 8 hours (29.6 ± 12.0 μmol/L). In the white group, a less remarkable change in mean cysteinylglycine level was observed, with a peak after 4 hours (16.3 ± 4.3 μmol/L).Conclusions: The findings of this study suggest that, in addition to lower plasma tHcy levels, the metabolism of plasma tHcy is different in black people than in white people after methionine loading. This difference may be due to different alimentary habits associated with a reduced dietary availability of methionine. Moreover, the higher plasma levels of glutathione before and after methionine loading appear to occur exclusively in black people compared with whites and correspond with the variation of cysteinylglycine, suggesting that, in addition to nutritional factors, a racial component may contribute to the difference in plasma levels of tHcy. This difference also might explain, in part, the lower prevalence of coronary heart disease in black people living in Burkina Faso compared with that in other populations.     

前体氨基酸对维生素B12发酵合成的影响

谷氨酸、苏氨酸、甘氨酸和甲硫氨酸是维生素B12合成的重要前体。在脱氮假单胞菌（Pseudomonas denitrifican）发酵的产物合成期以补加的方式考察了这4种氨基酸对维生素B12合成的影响。在合成培养基的基础上,通过单因素添加试验分别考察了这些氨基酸对维生素B12合成的影响,发现谷氨酸、甘氨酸和苏氨酸影响显著;并进一步利用三因素三水平的正交试验设计考察了氨基酸混合添加对菌体生长和维生素B12合成的影响,结果表明谷氨酸是最主要的影响因素,并且发现同时添加多种氨基酸更有利。当添加量为谷氨酸0.45 g/L、苏氨酸0.20 g/L、甘氨酸0.15 g/L时,得到的菌体量和维生素B12产量分别比对照组提高了13.1%和46.0%。     

甲硫氨酸维生素B_1对妊娠期肝内胆汁淤积症模型大鼠的治疗作用

目的探讨甲硫氨酸维生素B1针（甲维比）对妊娠期肝内胆汗淤积症（intrahepatic cholestasis of pregnancy,ICP）模型大鼠的治疗作用。方法妊娠大鼠48只,随机分为正常妊娠组、模型组、甲维比高剂量组2ml/（kg·d）、甲维比中剂量组1ml/（kg·d）、甲维比低剂量组0.5ml/（kg·d）、腺苷蛋氨酸组100mg/（kg·d）。从其妊娠第12天开始肌内注射苯甲酸雌二醇2.5mg/（kg·d）,连续6d,同时给药1周。正常妊娠组与模型组均肌注等容积蒸馏水。检测大鼠血清总胆红素（TBIL）、丙氨酸氨基转移酶（ALT）、总胆汁酸（TBA）、雌二醇（E2）水平;并比较各组大鼠肝脏组织病理变化;运用免疫组化法测定大鼠肝组织Th1细胞因子及核因子NF-κB的表达。结果甲维比高、中剂量治疗组及腺苷蛋氨酸组均较模型组大鼠流产率、胚胎致死率显著降低（P〈0.01）,大鼠血清TBIL、ALT、TBA、E2水平也降低（P〈0.01）,Th1细胞因子及核因子NF-κB的表达下调（P〈0.01）,大鼠的肝脏病理变化得到较大改善。结论甲维比可通过降低模型大鼠肝组织Th1细胞因子及核因子NF-κB的表达对ICP模型大鼠发挥明显的治疗作用。     

蛋氨酸合酶基因A275 6G位点多态性与非综合征型唇腭裂的关联性研究

Objective To study the association of the A2756G polymorphism of the methionine synthase (MS) gene with nonsyndromie cleft lip with or without cleft palate (NSCL/P) in Chinese. Methods Ninety-seven NSCL/P case-parent triads were selected as the case group. One hundred and four healthy subjects and their biological parents were selected as control group. For all subjects the A2756G polymorphism of the MS gene was examined by PCR-RFLP method. Results There was no statistical difference in genotype and allele frequencies for MS A2756G variants among family members between case group and control group. The GG genotype was not detected in the offsprings and mothers. The odds ratio and confidence interval of genotype AG in offspring, father and mother were 1.78(0.74-4.34), 0.80(0. 36-1.79) and 1.26(0. 54-2.93) respectively. The odds ratio and confidence interval of allele G in offspring, father and mother were 1.70(0.78-3.73), 0. 88(0. 49-1. 75) , and 1.23(0.59-2.60) respectively. The G allele did not increase the risk of NSCL/P. Transmission disequilibrium test (TDT) analysis yielded no evidence of linkage disequilibrium (χ2=0.034,P>0. 05). The results of haplotype-based haplotype relative risk (HHRR) analysis (χ2=0.03,P>0.05) and family-based association tests (FBAT) (Z=0. 186, P> 0.05) failed to show association between the MS A2756G variant and the risk of NSCL/P. Conclusion The A2756G polymorphism of the MS gene was not associated with NSCL/P in Chinese in the present study.     

Epileptic seizures and survival in early disease of grade 2 gliomas

Background and purpose:  The aims of this study were (i) to determine the correlation between seizure activity and the metabolic rate of the tumour measured by ¹¹C-methionine PET (MET PET) in patients with grade 2 gliomas, and (ii) to assess the prognostic impact of early seizure manifestations on patient survival.
Methods:  In this retrospective review, early seizure manifestations were studied in 101 patients with supratentorial grade 2 gliomas subjected to MET PET as part of the pre-treatment tumour investigation. Seizure manifestations as a variable was then used in multivariate survival analyses, together with established prognostic factors for this patient group.
Results:  Of all 101 cases, 88 patients had seizures at tumour presentation. Forty-seven were seizure free at the early stage of the disease, whereas 54 had recurrent seizures. Patients with seizures at tumour presentation had a more favourable outcome before and after ( P  = 0.006) adjustment for conventional prognostic factors. However, for those who continued to have seizures early in the disease, the outcome was worse ( P  = 0.003). We found no significant correlation between MET PET and the seizure manifestations of the patients.
Conclusion:  The presence and termination of early seizure manifestations may be favourable prognostic factors in patients with low-grade gliomas.     

Metabolic profiling studies on the toxicological effects of realgar in rats by H NMR spectroscopy

The toxicological effects of realgar after intragastrical administration (1 g/kg body weight) were investigated over a 21 day period in male Wistar rats using metabonomic analysis of ¹H NMR spectra of urine, serum and liver tissue aqueous extracts. Liver and kidney histopathology examination and serum clinical chemistry analyses were also performed. ¹H NMR spectra and pattern recognition analyses from realgar treated animals showed increased excretion of urinary Kreb's cycle intermediates, increased levels of ketone bodies in urine and serum, and decreased levels of hepatic glucose and glycogen, as well as hypoglycemia and hyperlipoidemia, suggesting the perturbation of energy metabolism. Elevated levels of choline containing metabolites and betaine in serum and liver tissue aqueous extracts and increased serum creatine indicated altered transmethylation. Decreased urinary levels of trimethylamine-N-oxide, phenylacetylglycine and hippurate suggested the effects on the gut microflora environment by realgar. Signs of impairment of amino acid metabolism were supported by increased hepatic glutamate levels, increased methionine and decreased alanine levels in serum, and hypertaurinuria. The observed increase in glutathione in liver tissue aqueous extracts could be a biomarker of realgar induced oxidative injury. Serum clinical chemistry analyses showed increased levels of lactate dehydrogenase, aspartate aminotransferase, and alkaline phosphatase as well as increased levels of blood urea nitrogen and creatinine, indicating slight liver and kidney injury. The time-dependent biochemical variations induced by realgar were achieved using pattern recognition methods. This work illustrated the high reliability of NMR-based metabonomic approach on the study of the biochemical effects induced by traditional Chinese medicine.     

Sarcolipin and phospholamban as regulators of cardiac sarcoplasmic reticulum Ca2+ ATPase

The cardiac sarcoplasmic reticulum calcium ATPase (SERCA2a) plays a critical role in maintaining the intracellular calcium homeostasis during cardiac contraction and relaxation. It has been well documented over the years that altered expression and activity of SERCA2a can lead to systolic and diastolic dysfunction. The activity of SERCA2a is regulated by two structurally similar proteins, phospholamban (PLB) and sarcolipin (SLN). Although, the relevance of PLB has been extensively studied over the years, the role SLN in cardiac physiology is an emerging field of study. This review focuses on the advances in the understanding of the regulation of SERCA2a by SLN and PLB. In particular, it highlights the similarities and differences between the two proteins and their roles in cardiac patho-physiology.