样本采集时间对老年慢性胃炎患者^(13)C-尿素呼气试验结果的影响

目的:分析样本采集时间对老年慢性胃炎患者^(13)C-尿素呼气试验结果的影响。方法:选取2019年6月—2021年6月山东省荣军总医院收治的150例老年慢性胃炎患者作为研究对象。所有患者于空腹及餐后3 h进行^(13)C-尿素呼气试验,并以快速尿素酶检测结果作为“金标准”,比较两个样本采集时间^(13)C-尿素呼气试验结果的准确率、特异度及灵敏度。结果:空腹时采集样本的^(13)C-尿素呼气试验准确率、灵敏度高于餐后3 h,差异有统计学意义(P<0.05)。结论:老年慢性胃炎患者空腹时进行^(13)C-尿素呼气试验的诊断效能较高。

Role of the^(13)C-methacetin breath test in the assessment of acute liver injury in a rat model

AIM: To evaluate the role of the 13C-methacetin breath test(13C-MBT) in the assessment of acute liver injury in a rat model.METHODS: Acute liver injury in rats was induced by a single intraperitoneal injection of D-galactosamine(D-GalN). Forty-eight male Sprague-Dawley rats were randomly assigned to a control group(n = 8) and five model groups(each n = 8), and acute liver injury was assessed at different time points(6, 12, 24, 48 and 72 h) after D-GalN injection. The 13C-MBT, biochemical tests, 15-min retention rate of indocyanine green(ICGR15), and liver biopsy were performed and compared between the control and model groups. Correlations between parameters of the 13C-MBT(Tmax, MVmax, CUM120 and DOBmax), biochemical tests, ICGR15 and liver necrosis score were also analyzed using Spearman'scorrelation analysis.RESULTS: Tmax, MVmax, CUM120 and DOBmax, as well as most of the traditional methods, correlated with the liver necrosis score(r = 0.493, P < 0.05; r =-0.731, P < 0.01; r =-0.618, P < 0.01; r =-0.592, P < 0.01, respectively). MVmax, CUM120 and DOBmax rapidly decreased and were lower than those in the controls as early as 6 h after D-GalN injection(3.84 ± 0.84 vs 5.06 ± 0.78, P < 0.01; 3.35 ± 0.72 vs 4.21 ± 1.44, P < 0.05; 52.3 ± 20.58 vs 75.1 ± 9.57, P < 0.05, respectively) and reached the lowest point 24 h after D-GalN injection. MVmax, CUM120 and DOBmax returned to normal levels 72 h after D-GalN injection and preceded most of the traditional methods, including liver biopsy.CONCLUSION: The 13C-MBT is a sensitive tool for the timely detection of acute liver injury and early prediction of recovery in a rat model. Further clinical studies are warranted to validate its role in patients with acute liver injury.

Effect of posture on ^(13)C-urea breath test in partial gastrectomy patients

AIM: To investigate whether posture affects the accuracy of 13C-urea breath test(13C-UBT) for Helicobacter pylori(H. pylori) detection in partial gastrectomy patients. METHODS: We studied 156 consecutive residual stomach patients, including 76 with H. pylori infection(infection group) and 80 without H. pylori infection(control group). H. pylori infection was confirmed if both the rapid urease test and histology were positive during gastroscopy. The two groups were divided into four subgroups according to patients' posture during the 13C-UBT: subgroup A, sitting position; subgroup B, supine position; subgroup C, right lateral recumbent position; and subgroup D, left lateral recumbent position. Each subject underwent the following modified 13C-UBT: 75 mg of 13C-urea(powder) in 100 m L of citric acid solution was administered, and a mouth wash was performed immediately; breath samples were then collected at baseline and at 5-min intervals up to 30 min while the position was maintained. Seven breathsamples were collected for each subject. The cutoff value was 2.0‰.RESULTS: The mean delta over baseline(DOB) values in the subgroups of the infection group were similar at 5 min(P > 0.05) and significantly higher than those in the corresponding control subgroups at all time points(P < 0.01). In the infection group, the mean DOB values in subgroup A were higher than those in other subgroups within 10 min and peaked at the 10-min point(12.4‰± 2.4‰). The values in subgroups B and C both reached their peaks at 15 min(B, 13.9‰± 1.5‰; C, 12.2‰± 1.7‰) and then decreased gradually until the 30-min point. In subgroup D, the value peaked at 20 min(14.7‰± 1.7‰). Significant differences were found between the values in subgroups D and B at both 25 min(t = 2.093, P = 0.043) and 30 min(t = 2.141, P = 0.039). At 30 min, the value in subgroup D was also significantly different from those in subgroups A and C(D vs C: t = 6.325, P = 0.000; D vs A: t = 5.912, P = 0.000). The mean DOB values of subjects with Billroth Ⅰ anastomosis were higher than those of subjects with Billroth Ⅱ anastomosis irrespectively of the detection time and posture(P > 0.05).CONCLUSION: Utilization of the left lateral recumbent position during the procedure and when collecting the last breath sample may improve the diagnostic accuracy of the 13C-UBT in partial gastrectomy patients.

An optimized ^(13)C-urea breath test for the diagnosis of H pylori infection

AIM： To validate an optimized ^13C-urea breath test （^13C-UBT） protocol for the diagnosis of H pylori infection that is cost-efficient and maintains excellent diagnostic accuracy. METHODS： 70 healthy volunteers were tested with two simplified ^13C-UBT protocols, with test meal （Protocol 2） and without test meal （Protocol 1）. Breath samples were collected at 10, 20 and 30 rain after ingestion of 50 mg ^13C-urea dissolved in 10 mL of water, taken as a single swallow, followed by 200 mL of water （pH 6.0） and a circular motion around the waistline to homogenize the urea solution. Performance of both protocols was analyzed at various cut-off values. Results were validated against the European protocol. RESULTS： According to the reference protocol, 65.7% individuals were positive for H pylori infection and 34.3% were negative. There were no significant differences in the ability of both protocols to correctly identify positive and negative H pylori individuals. However, only Protocol 1 with no test meal achieved accuracy, sensitivity, specificity, positive and negative predictive values of 100%. The highest values achieved by Protocol 2 were 98.57%, 97.83%, 100%, 100% and 100%, respectively.CONCLUSION： A 10 min, 50 mg ^13C-UBT with no test meal using a cut-off value of 2-2.5 is a highly accurate test for the diagnosis of H pylori infection at a reduced cost.

Capsule ^(13)C-urea breath test for the diagnosis of Helicobacter pylori infection

AIM: To compare the accuracy of capsule 13C-urea breath test (UBT) with conventional invasive methods for the diagnosis of Helicobacter pylori infection.METHODS: One hundred patients received CLO test,histological examination, culture and 100- or 50-mg capsule UBT for the diagnosis of Hpyloriinfection. Hpylori infection was defined as those with positive culture or positive results from both histology and CLO test.RESULTS: Both the sensitivity and specificity of the 100-mg capsule UBT (n = 50) were 100%. The sensitivity and specificity of the 50-mg capsule UBT (n = 50) were 96.4and 100%, respectively. Taken together, the accuracy of capsule UBT (n=100) was higher than that of CLO test,histology and culture (100% vs 92%, 91% and 89%,respectively; P= 0.035, 0.018 and 0.005, respectively). Our data showed that the optimal timing of sampling for 100-and 50-mg capsule UBT was 15-30 and 6-15 min, respectively.CONCLUSION: Capsule UBT has a higher accuracy compared with biopsy-based tests. It is an ideal method for the diagnosis of Hpyloriinfection.

Cost effectiveness analysis of population-based serology screening and ^(13)C-Urea breath test for Helicobacter pylori to prevent gastric cancer:A markov model

AIM:To compare the costs and effectiveness of no screening and no eradication therapy, the population- based Helicobacter pylori (H pylori) serology screening with eradication therapy and 13C-Urea breath test (UBT) with eradication therapy. METHODS:A Markov model simulation was carried out in all 237 900 Chinese males with age between 35 and 44 from the perspective of the public healthcare provider in Singapore. The main outcome measures were the costs, number of gastric cancer cases prevented, life years saved, and quality-adjusted life years (QALYs) gained from screening age to death. The uncertainty surrounding the cost-effectiveness ratio was addressed by one-way sensitivity analyses. RESULTS:Compared to no screening, the incremental cost-effectiveness ratio (ICER) was $16 166 per life year saved or $13 571 per QALY gained for the serology screening, and $38 792 per life year saved and $32 525 per QALY gained for the UBT. The ICER was $477 079 per life year saved or $390 337 per QALY gained for the UBT compared to the serology screening. The cost- effectiveness of serology screening over the UBT was robust to most parameters in the model. CONCLUSION:The population-based serologyscreening for H pylori was more cost-effective than the UBT in prevention of gastric cancer in Singapore Chinese males.

Delayed Gastric Emptying in Anorexic Adolescents Measured with the ¹³C Octanoic Acid Breath Test

Many gastrointestinal complaints and motility disorders are described in patients suffering from different eating disorders. These have a negative impact on refeeding. This report evaluated–on admission-gastric emptying of a standardized solid meal with 13C octanoic acid breath test in anorexic adolescents. The results were compared with age and gender matched controls. Gastric emptying data were related to a subjective symptom score. 21 Anorexic girls and 3 boys (mean age: 15.6 y ± 1.3 y), body mass index (mean 15.6 kg/m2 ± 1.6 kg/m2), weight loss (mean: 22.2% ± 10.7%) were studied. T? of the gastric emptying time exceeded the P95 in 14/24 (58%) patients, classified as having delayed gastric emptying (DGE). One patient (4%) had a T? exceeding P75 and was classified as slow (SGE), whereas 9/24 (38%) patients had normal gastric emptying (NGE). In comparison to NGE, subjects with DGE had significantly higher symptom scores (p = 0.01) and more weight loss. The DGE and SGE patients lost 25.29% and 21.38% of weight respectively, whereas a weight loss of 17.64% was found in anorexics with NGE. In conclusion, gastric emptying is delayed in patients with anorexia. This is associated with more significant gastrointestinal symptoms and higher weight loss.

^(13)C-methacetin breath test reproducibility study reveals persistent CYP1A2 stimulation on repeat examinations

AIM: To find the most reproducible quantitative parameter of a standard 13C-methacetin breath test (13C-MBT). METHODS: Twenty healthy volunteers (10 female, 10 male) underwent the 13C-MBT after intake of 75 mg 13C-methacetin p.o. on three occasions. Short-and medium-term reproducibility was assessed with paired examinations taken at an interval of 2 and 18 d (medians), respectively. RESULTS: The reproducibility of the 1-h cumulative 13C recovery (AUC0-60), characterized by a coefficient of variation of 10%, appeared to be considerably better than the reproducibility of the maximum momentary 13C recovery or the time of reaching it. Remarkably, as opposed to the short gap between consecutive examinations, the capacity of the liver to handle 13C-methacetin increased slightly but statistically significantly when a repeat dose was administered after two to three weeks.Regarding the AUC0-60, the magnitude of this fixed bias amounted to 7.5%. Neither the time gap between the repeat examinations nor the gender of the subjects affected the 13C-MBT reproducibility. CONCLUSION: 13C-MBT is most reproducibly quantified by the cumulative 13C recovery, but the exactitude thereof may be modestly affected by persistent stimulation of CYP1A2 on repeat examinations.

Prognostic value of ^(13)C-phenylalanine breath test on predicting survival in patients with chronic liver failure

AIM: To evaluate the prognostic value of percentage of 13C-phenylalanine oxidation (13C-PheOx) obtained by 13C-phenylalanine breath test (13C-PheBT) on the survival of patients with chronic liver failure. METHODS: The hepatic function was determined by standard liver blood tests and the percentage of 13C-PheOx in 118 chronic liver failure patients. The follow-up period was of 64 mo. Survival analysis was performed by the Kaplan-Meier method and variables that were significant (P < 0.10) in univariate analysis and subsequently introduced in a multivariate analysis according to the hazard model proposed by Cox. RESULTS: Forty-one patients died due to progressive liver failure during the follow-up period. The probability of survival at 12, 24, 36, 48 and 64 mo was 0.88, 0.78, 0.66, 0.57 and 0.19, respectively. Multivariate analysis demonstrated that Child-Pugh classes, age, creatinine and the percentage of 13C-PheOx (HR 0.338, 95% CI: 0.150-0.762, P = 0.009) were independent predictors of survival. When Child-Pugh classes were replaced by all the parameters of the score, only albumin, bilirubin, creatinine, age and the percentage of 13C-PheOx (HR 0.449, 95% CI: 0.206-0.979, P = 0.034) were found to be independent predictors of survival.CONCLUSION: Percentage of 13C-PheOx obtained by 13C-PheBT is a strong predictor of survival in patients with chronic liver disease.

Can pH Monitoring Predict Gastric Emptying Measured by ¹³C-Acetate Breath Test in Gastroesophageal Reflux with Neurological Impairment?

Introduction: Delayed gastric emptying (DGE) often occurs in patients with gastroesophageal reflux (GER) due to neurological impairment (NI). 13C has been used as an alternative tool for measuring the gastric emptying rates. The aim of this study was to predict gastric emptying in children with GER using 13C-acetate breath test (ABT) by 24-hour pH monitoring. Methods: Nineteen patients were divided into 2 groups: a DGE group with NI (14 patients), and normal-emptying group without NI (5 patients). The liquid test meal consisted of RacolTM (5 ml/kg) mixed with 13C-acetate (50 mg for infants, 100 mg for children, and 150 mg for adolescents). 13CO2 was measured using a gas chromatograph-isotope ratio mass spectrometer. The results are expressed as the % of 13C expired per hour and cumulative 13C excretion over a 3-hour periods including the parameters of half excretion and lag time. Results: The mean half excretion time was 1.762 hour in the DGE group and 1.095 hour in the normal-emptying group (P = 0.0196). The mean lag time was 0.971 hour in the DGE group and 0.666 hour in the normal-emptying group (P = 0.0196). Therefore, DGE was significantly more prevalent in the DGE compared to the normal-emptying group. The percentage of the time when the pH was less than 4 on 24-hour esophageal pH monitoring was 21.6% ± 9.2% in the DGE group and 28.5% ± 11.6% in the normal-emptying group (P = 0.4634). Conclusion: The percentage of time when the pH is less than 4 on 24-hour pH monitoring cannot predict DGE measured by the 13C-ABT in GER.

基于不同纤维改性的OGFC-13沥青混合料路用性能研究

纤维沥青利用纤维的改性作用改善混凝土材料的路用性能。为探究OGFC-13沥青混合料在各类纤维不同体积掺量条件下的路用性能表现,本文特制备聚丙烯腈纤维、聚酯纤维、木质素纤维、玄武岩纤维4种纤维外掺剂的沥青混合料进行路用性能试验。研究结果表明:(1)OGFC-13沥青混合料随纤维掺量的增加,其动稳定度不断增长,当各种纤维掺量超过0.3%时,动稳定度呈下降趋势;(2)当纤维体积掺量为0.3%时,含玄武岩纤维的沥青混合料动稳定度为3252次/mm,高温稳定性表现最佳;(3)当聚酯纤维与玄武岩纤维掺量为0.2%时,沥青混合料低温最大弯拉应变相同,为2834,但聚酯纤维在纤维沥青混合料低温抗裂性能方面的作用存在不稳定性;(4)掺入纤维材料的OGFC-13沥青混合料排水性能呈下降趋势,尤其是木质纤维对渗透系数的影响最大,当掺量为0.2%时,渗水系数由1154 ml/s陡降至635 ml/s,降幅达到44.97%;(5)综合来看,玄武岩纤维在OGFC-13沥青混合料中的改性效果最佳,但其掺量体积分数应控制在0.3%以内。本文成果可为温拌沥青薄层罩面的工程应用提供一点借鉴。

镍铁矿渣纤维对SMA-13沥青混合料高温稳定性的影响研究

纤维沥青混凝土具有优异的抵抗变形能力,耐久性较好,受到业内广泛关注。文章选用一种新型矿物纤维——镍铁矿渣纤维作为SMA-13混合料的纤维改性剂,通过马歇尔试验和车辙试验对改性后SMA-13沥青混合料的高温稳定性进行研究。结果表明:1#镍铁矿渣纤维掺量为0.4%时,对SMA-13沥青混合料马歇尔模数的提升效果最为明显,其改性效果优于木质素纤维;1#和3#镍铁矿渣纤维均可较好提升SMA-13沥青混合料的车辙动稳定度,且掺量达到0.4%以上时效果略优于木质素纤维的改善效果。综合高温性能测试结果,1#镍铁矿渣纤维提升SMA-13混合料高温性能的效果最佳,其最优掺量为0.4%。

胆固醇-3,4-^(13)C_(2)的合成

针对我国胆固醇-3,4-^(13)C_(2)产品制备方法空白,以乙酸苯酯-1,2-^(13)C_(2)和4-胆甾烯-3-酮为起始原料,合成胆固醇-3,4-^(13)C_(2)。总体标记合成路线采用胆固醇基础结构拆分后引入标记砌块再重构目标化合物结构的方案,其中4-胆甾烯-3-酮通过开环氧化、合环得到标记前体,乙酸苯酯-1,2-^(13)C_(2)作为^(13)C标记引入砌块与标记前体通过乙酰化反应得到乙酰化标记中间体,最后乙酰化标记中间体再经过碳环重构、酯化、还原反应得到^(13)C二标记的类固醇激素类化合物胆固醇-3,4-^(13)C_(2)。其中还原反应显示出一定的不对称合成现象。以投入的乙酸苯酯-1,2-^(13)C_(2)的物质的量计算反应总产率为16.2%。所得终产品经MS、NMR和HPLC表征确认,液相色谱纯度≥96%,液相质谱检测丰度≥98 atom%^(13)C,该产品可用于临床质谱、生物医药等领域检测用稳定同位素内标试剂以及临床质谱用疾病筛查试剂盒原料。

^(13)C尿素呼气试验检测幽门螺杆菌感染的临床应用

目的探讨^(13)C尿素呼气试验检测幽门螺杆菌感染的临床诊断价值。方法选择2022年1月至2023年7月100例上海未凡医学检验实验室接受检查的上腹部不适患者100例作为研究对象。所有患者均行快速脲酶试验(RUT)和^(13)C尿素呼气试验。以组织学检查作为诊断金标准,比较2种方法对患者各种疾病诊断的准确性、阳性率。对2种方法的诊断性能(灵敏度、特异度、准确性、阴性预测值、阳性预测值)进行评估。结果100例上腹部不适患者中,90例经病理检查确诊。^(13)C尿素呼气试验对十二指肠炎和消化性溃疡的诊断阳性率高于RUT(P<0.05)。2种方法对胃息肉、慢性胃炎、胃癌的诊断阳性率比较,差异无统计学意义(P>0.05)。与RUT相比,^(13)C尿素呼气试验具有更高的灵敏度、特异度、准确性、阳性预测值和阴性预测值。2种方法的特异度、准确性差异有统计学意义(P<0.05),而敏感性、阴性预测值、阳性预测值差异无统计学意义(P>0.05)。结论^(13)C尿素呼气试验和RUT均是检测幽门螺杆菌感染的有效诊断方法,但^(13)C尿素呼气试验具有更高的诊断阳性率和整体诊断效能。

OGFC-13沥青混凝土面层施工技术研究与分析

为提升OGFC-13沥青混凝土面层施工质量,文章以深汕西高速改扩建TJ5标项目为例,选取其中一段作为实验段,旨在对OGFC-13沥青混凝土面层的施工技术进行研究与分析。通过对施工方案与工艺、试验检测与成果等进行详细论述,总结了OGFC-13沥青混凝土面层施工的关键技术要点和操作要求。通过试验段的实际应用,验证了所提出的生产配合比确定、拌合料参数确定、摊铺及碾压参数确定和松铺系数的有效性,为类似工程施工提供一定的借鉴指导。

橡胶/SBS复合改性SMA-13结构参数及路用性能研究

为全面评价橡胶/SBS复合改性SMA-13的结构参数及路用性能,通过车辙、浸水马歇尔、冻融劈裂、汉堡车辙、小梁弯曲等试验,分析了SMA-13混合料的高温、低温、水稳定性等路用性能,通过单轴压缩试验分析了动态模量。研究表明:橡胶/SBS复合改性SMA-13的动态模量为5764 MPa,可为橡胶/SBS复合改性路面结构设计提供参考依据;汉堡车辙试验加载20000次,橡胶/SBS复合改性SMA-13最大车辙深度为1.55 mm,且未出现剥落点,在水温耦合作用下具有良好的高温稳定性能;小梁弯曲试验中最大弯拉应变远高于现行设计规范要求,表明其具有良好的低温抗裂性能;残留稳定度、冻融劈裂和汉堡车辙试验结果显示橡胶/SBS复合改性SMA-13具有良好的抗水损坏性能。橡胶/SBS复合改性沥青在消纳废胎胶粉的同时,保证了沥青混合料综合使用性能,具有巨大的应用前景。

^(13)C-尿素呼气试验诊断儿童幽门螺杆菌感染的探讨

为探讨^(13)C-尿素呼气试验(^(13)C-UBT)对儿童幽门螺杆菌(HP)感染检测的可靠性,对52例4～13岁有消化道症状的儿童作^(13)C-UBT检测,并与HP的尿素酶试验、细菌培养和病理学检查比较。结果:^(13)C-UBT检测HP阳性39例,阴性10例,敏感性100％,特异性76.92％。其中^(13)C-UBT诊断HP感染与胃粘膜3种检测HP方法完全符合33例(63.46％),与胃粘膜两种方法完全符合44例(84.61％),胃粘膜一种方法完全符合49例(94.23％)。结论提示:^(13)C-UBT有高度敏感性及特异性,对确诊儿童胃内HP感染状态是一种可靠、无创伤性的诊断方法,值得推广应用。

L-[1-^(13)C]苯丙氨酸呼气试验定量检测肝功能研究

为评价L-[1- 13C]苯丙氨酸呼气试验检测肝功能的可行性和有效性,健康自愿者、代偿期肝硬化患者和失代偿期肝硬化患者各10名,口服100mg L-[1- 13C]苯丙氨酸后进行呼气试验。应用气体同位素比值质谱仪测量服药前和服药后至360min各时间点气样中的13C丰度,得到了不同时间的13C的排除速率13CO2ERt (per-centage 13C excretion rate) (% 13C剂量/h)和各时相内的累计13C排除率13Ccumt (percentage 13C cumulative excre-tion) (% 13C剂量)。将呼气试验参数30 min 13C排除速率13CO2ER30和75min累计13C排除率13Ccum75在正常对照组、肝硬化代偿组、肝硬化失代偿组之间进行两两比较,并分别与各肝功能临床生化指标进行相关性分析。结果显示,13CO2ER30(肝硬化代偿组:7.4% 13C剂量/h?.0% 13C剂量/h;肝硬化失代偿组:3.5% 13C剂量/h1.1% 13C剂量/h;正常对照组:12.1% 13C剂量/h2.1% 13C剂量/h)和13Ccum75(肝硬化代偿组:7.0% 13C剂量1.1% 13C剂量;肝硬化失代偿组:3.8% 13C剂量1.0% 13C剂量;正常对照组:10.6% 13C剂量1.6% 13C剂量)在各组之间差异均具有显著性(P<0.001);13CO2ER30和13Ccum75与部分肝功能生化指标存在显著相关性(P<0.05)。表明口服L-[1- 13C]苯丙氨酸呼气试验是一种简便、灵敏、特异、定量的肝功能即时检测?

国产^(13)C-葡萄糖呼气试验检测糖尿病小鼠胰岛素抵抗的实验研究

目的拟在糖尿病小鼠模型上建立一个无创的13C-葡萄糖呼气试验检测胰岛素抵抗(IR)的方法,并评估其与其他IR指数的相关性。方法四氧嘧啶尾静脉注射法制作糖尿病小鼠模型。多时间点采集小鼠13C-葡萄糖(5 mg/kg)灌胃后呼出的气样。红外线同位素能谱仪测定气样,以90 min 13CO2丰度变化值(C90 min)作为IR参数,评估糖尿病小鼠的IR情况及其在1 U外源性胰岛素干预后的IR变化。测定糖尿病小鼠的空腹血糖及空腹胰岛素值,并以此来计算临床IR指数:稳态模型胰岛素抵抗评价指数(HOMA-IR)和定量胰岛素敏感性检测指数(QUICKI)。分别分析C90 min与HOMA-IR或QUICKI之间的相关性。结果糖尿病小鼠的C90 min值明显低于正常对照小鼠,分别为(0.79±0.18)%和(1.19±0.31)%(t=2.470,P<0.05)。1 U外源性胰岛素干预后,糖尿病小鼠的C90 min值显著增加至(1.17±0.25)%(t=-2.522,P<0.05)。相关性分析显示,C90 min与HOMA-IR(r=-0.64,P<0.05)或QUICKI(r=0.88,P<0.01)均有良好的相关性。结论 13C-葡萄糖呼气试验能够灵敏反映糖尿病小鼠的IR变化,其检测结果与目前临床IR指数有良好的相关性。

自制美沙西汀-甲氧基-^(13)C的表征

采用新的方法,以甲醇-13C为原料直接合成了美沙西汀-甲氧基-13C,并对其进行了HPLC、LC-MS和1HMNR等分析。结果表明,所合成的样品是目标产品,产率为70.0%,13C丰度为99%,纯度为99.8%。与经典的合成方法比较,本方法具有较好的经济效益。使用本方法自制的美沙西汀-甲氧基-13C进行小鼠13C-呼吸试验,结果表明,美沙西汀-甲氧基-13C可以在小鼠活体状态下正确评估其损伤和恢复情况。