稳定性核素测定大鼠小肠蛋白质合成

目的：建立稳定性核素（[L-^15N]亮氨酸）测定大鼠小肠蛋白质合成率的方法。方法：分别测定静脉注射相同剂量[L-^15N]亮氨酸不同时相的大鼠小肠^15N丰度及不同剂量[L-^15N]亮氨酸同一时相的大鼠小肠^15N丰度。结果：大鼠小肠游离氨基酸池中^15N核素丰度在注射后0．5h内呈线性上升并达高峰，维持4h后缓慢下降，小肠蛋白质中的^15N丰度0．5h至12h基本维持不变；随着注射剂量的增加，大鼠小肠蛋白质分数合成率（FSR）亦增加，当[L-^15N]亮氨酸剂量在1．0mmol／kg以上，FSR并不随施加[L15N]亮氨酸剂量的加大而增加。结论：在进行大鼠小肠蛋白质合成率测定时，一次性静脉注射的测量最佳时限为0．5h，剂量为1．0mmol／kg。     

Positron emission tomography in oncology

Summary. The particular advantages of positron emission tomography (PET) technique are that it has higher sensitivity, higher resolution, and a higher quality of image than that found in conventional nuclear medicine. The possibility of quantification and the wide range of useful tracers have raised expectations of this new method. To date, most of the human PET cancer studies have been performed with [¹⁸F]fluorodeoxyglucose (FDG) or [¹¹CJmethionine. These are good imaging agents for tumours. However, more specific radiopharmaceuticals are required if other features of tumour metabolism are to be observed, f¹¹Thymidine may prove to be a good tracer for quantitative measurements of tumour proliferation and [¹⁸F]misonidazole has been suggested for imaging of hypoxia.     

Nutritional Aspects of Breath Testing Based on Stable Isotopes

Stable isotope methodologies offer a number of possibilities for the nutritional assessment of many different processes and metabolic pathways. The application of stable isotopes has been boosted by the development of new mass spectrometers, lower costs of probes, and the risks associated with radioactive tracers. The use of ¹³C as a tracer offers all the advantages of stable isotopes and has been widely applied for measuring various types of metabolic processes. This review is focused on clinical and nutritional assessments using ¹³C breath tests.     

常规肺功能与肺胺代谢功能初步探讨

本文报告了36例研究对象肺廓清~(131)I-三甲基羟基-间碘-苯二胺(~(131)I-HIPDM)结果,其中31例作了常规肺功能及动脉血气检查。结果表明不同组间肺廓清~(131)I-HIPDM速率不同,能形成一个新的肺功能障碍指数。右肺廓清~(131)I-HIPDM快相与用力肺活量(FVC)、第1秒用力呼气量(FEV_1)、功能残气量(FRC)、残气量(RV)肺总量(TLC)相关P<0.01;与最大呼气流量(PEFR)、肺活量(VC)、最大通气量(MVV)、动脉血氧分压(PaO_2)相关P<0.05。肺廓清~(131)I—HIPDM速率反映了肺功能状态,对疾病分期及早期肺功能损伤检测优于常规肺功能。     

~(131)I治疗Graves’病后发生甲低与TGA,TMA及TRAb的关系

目的 :从甲状腺自身免疫方面探讨1 3 1 I治疗甲亢的效果及甲低发生的因素。方法 :选择1 3 1 I治疗的88例Graves’病甲亢患者随访 3年 ,分为第 1组 (TGA、TMA、TRAb均阳性 )和第二组 (TGA、TMA阴性 ,TRAb阳性 )。采用x2 分析自身抗体水平与甲低发生的关系。结果 :1组甲低发生率为 31 4 % ,2组为 3 8% ,1组明显高于 2组 ,差异有显著性。结论 :TGA、TMA和TRAb水平与确定1 3 1 I剂量及甲低的发生关系密切。认为TGA、TMA水平高的患者应酌情减少1 3 1 I用量     

Availability of glucose ingested during muscle exercise performed under acipimox-induced lipolysis blockade

This study investigated the percentage of carbohydrate utilization than can be accounted for by glucose ingested during exercise performed after the ingestion of the potent lipolysis inhibitor Acipimox. Six healthy male volunteers exercised for 3 h on a treadmill at about 45% of their maximal oxygen uptake, 75 min after having ingested 250 mg of Acipimox. After 15-min adaptation to exercise, they ingested either glucose dissolved in water, 50 g at time 0 min and 25 g at time 60 and 120 min (glucose, G) or sweetened water (control, C). Naturally labelled [¹³C]glucose was used to follow the conversion of the ingested glucose to expired-air CO₂. Acipimox inhibited lipolysis in a similar manner in both experimental conditions. This was reflected by an almost complete suppression of the exercise-induced increase in plasma free fatty acid and glycerol and by an almost constant rate of lipid oxidation. Total carbohydrate oxidation evaluated by indirect calorimetry, was similar in both experimental conditions [C, 182, (SEM 21); G, 194 (SEM 16) g · 3 h^–1], as was lipid oxidation [C, 57 (SEM 6); G, 61 (SEM 3) g · 3 h^–1]. Exogenous glucose oxidation during exercise G, calculated by the changes in¹³C:¹²C ratio of expired air CO₂, averaged 66 (SEM 5) g · 3 h^–1 (19% of the total energy requirement). Consequently, endogenous carbohydrate utilization was significantly smaller after glucose than after placebo ingestion: 128 (SEM 18) versus 182 (SEM 21) g · 3 h^–1, respectively (P < 0.05). Symptoms of intense fatigue and leg cramps observed with intake of sweet placebo were absent with glucose ingestion.In conclusion, we found glucose ingestion during 3-h exercise with lipolysis blockade could provide metabolic substrate permitting a significant sparing of endogenous carbohydrate and consequently an improvement in performance.     

Resistant Starch Production and Glucose Release from Pre‐Prepared Chilled Food: The SPUD Project

With an increasing prevalence of diabetes worldwide, effective dietary strategies for blood glucose control are crucial. As carbohydrates make up approximately 50% of the diet, it is neither practical nor advisable to avoid them altogether. Most of the carbohydrate in the diet is derived from starch, found in potatoes, pasta, rice and bread. These foods are often processed in some way before consumption, yet little is known about the effects processing, such as chilling and reheating, has on the glycaemic response, particularly when the food is consumed in the context of a mixed meal. This article introduces the SPUD project, a BBSRC DRINC‐funded initiative. Taking the potato as the model carbohydrate, this project will investigate, via in vitro and in vivo studies, the effects of domestic food processing techniques on the glycaemic response. A final study, utilising intrinsically labelled potato and a dual stable isotope methodology, will model glucose flux data to determine the underlying mechanisms of action.     

~3H-蛋氨酸/缬氨酸空肠喂饲在荷瘤大鼠体内的分布

目的 :观察3H 蛋氨酸 /缬氨酸空肠喂饲在荷瘤大鼠体内的分布。方法 :SD大鼠空肠造瘘 ,皮下接种Walker 2 5 6癌肉瘤 ,分A、B、C、D 4组。分别以平衡氨基酸、去蛋氨酸、平衡氨基酸、去缬氨酸空肠喂养 6d ,注入3H 蛋氨酸 /缬氨酸 7.4× 10 5Bq 0 .5 ,1,2 ,4h后测定肝、胰、小肠、肌肉、血浆及肿瘤组织的放射性强度 ,计算差示摄取比(DUR)。结果 :B组肿瘤组织 2h ,4hDUR高于A组 ,而血浆DUR各时点低于A组。D组肿瘤组织DUR各时点高于C组 ,而血浆DUR低于C组。结论 :3H 蛋氨酸 /缬氨酸在肿瘤组织摄取率高 ,去蛋氨酸 /缬氨酸空肠喂饲后 ,其摄取率更高。     

The continuing important role of radionuclide generator systems for nuclear medicine

In this review, the continuing importance and status of development of radionuclide generator systems for nuclear medicine are discussed. Radioisotope costs and availability are two important factors, and both nuclear reactors and accelerator facilities are required for production of the parent radioisotopes. Radionuclide generator research is currently focused on the development of generators which provide radioisotopes for positron emission tomography (PET) applications and daughter radioisotopes for various therapeutic applications which decay primarily by particle emission. Generator research continues to be influenced by developments and requirements of complementary technologies, such as the increasing availability of PET. In addition, the availability of a wide spectrum of tumor-specific antibodies, fragments, and peptides for radio-immunodiagnosis and radioimmunotherapy has stimulated the need for generator-derived radioisotopes. The advantages of treatment of arthritis of the synovial joints with radioactive particles (radiation synovectomy) may be expected to be of increasing importance as the elderly population increases, and many of these agents are prepared using generator-derived radioisotopes such as yttrium-90 and rhenium-188. Therapeutic use of the in vivo generator is a new approach, where the less radio-toxic parent radioisotope is used to prepare tissue-speciic therapeutic agents. Following in vivo site localization, decay of the parent provides the daughter for therapy at the target site. The principal foundation of most diagnostic agents will continue to require technetium-99m from the molybdenum-99/technetium-99m (Moly) generator. With the limited availability of nuclear reactors and facilities necessary for production and processing of fission ^99mTc and the significant issues and problems associated with radioactive waste processing, however, the possibility of utilizing lower specific activity ⁹⁹Mo produced from neutron activation of enriched ⁹⁸Mo may become practical in the future. Correspondence to: RE Knapp, Jr.     

Use of Stable Isotopes for Evaluation of Drug Delivery Systems: Comparison of Ibuprofen Release in Vivo and in Vitro from Two Biphasic Release Formulations Utilizing Different Rate-Controlling Polymers

Certain delivery systems are intended to release the active ingredient in different phases to obtain the desired therapeutic effect. For these formulations, such as a bilayer tablet, it is desirable to distinguish and measure the release of drug from the different phases simultaneously. Mass spectrometric methods were developed to measure three ibuprofen isotopomers in serum and two in dissolution fluid. The analytical methods were linear (r 0.992) over the concentration range of interest and recovery was greater than 99.2% for all isotopomers. Coadministration of [²H₀]ibuprofen, [²H₄]ibuprofen, and [²H₇]ibuprofen to male beagles demonstrated that the isotopomers were bioequivalent and verified the absence of any kinetic isotope effect due to deuterium incorporation (p = 0.286). These methods were then used to evaluate a bilayer tablet formulation composed of an immediate release layer of 100 mg [²H₄]ibuprofen and a sustained release layer with a drug load of 300 mg [²H₀]ibuprofen. Two different rate-controlling polymer matrices that provided similar in vitro dissolution profiles were compared in the sustained release phase, while the immediate release formulation remained the same. In male beagles, the HPMC matrix delivered a significantly greater amount of ibuprofen (p < 0.05). The AUC was threefold greater for HPMC (1067 ± 437 nmole * h/ml) versus EUDRAGIT^® (320 ± 51), and C_max was nearly four times greater (145 ± 62.1 nmole/ml for HPMC versus 37.9 ± 14.4 for EUDRAGIT^®). Although T_max for HPMC (3.4 ± 1.9 h) lagged behind EUDRAGIT^® (2.0 ± 0.82 h), the difference was not significant (p > 0.05). The immediate release layer was absorbed to the same extent as an oral solution (containing [²H₇]ibuprofen) that was administered concomitantly with the bilayer tablet. Using the stable isotope markers also demonstrated that the release rates of the two layers were independent of each other, both in vivo and in vitro. Stable isotope techniques are a useful tool in the development of biphasic release formulations since they can be used to determine proper drug load of each phase as well as the appropriate rate of release.