谷氨酰胺在危重病患者中的应用

目的探讨危重病患者中早期经静脉应用谷氨酰胺（glutamine，Gl）的临床价值。方法42例患者随机分成两组（对照组和Gln组），Gln组进行Gln治疗（100mL／d，共7d）。治疗前后检测患者体质量、白蛋白、谷胱甘肽（GSH）、握力的变化和肠功能不全的发生率。结果体质量两组治疗前后比较差异无显著性（P〉0．05）。白蛋白、握力和GSH Gl治疗后非常显著高于治疗前（P〈0．01）；白蛋白对照组治疗后较治疗前显著增高（P〈0．05），但握力和GSH治疗前后均无显著变化（P〉0.05）；肠功能不全的发生率Gln组为4．8％，显著低于对照组（28．6％，P〈0．05）。结论在危重病患者疾病早期通过静脉途径外源性地补充Gln，有效改善了患者的营养状况；使患者血浆中的GSH水平增高，加强了机体的抗氧化能力；减少了患者肠功能不全的发生率。     

Progress toward re‐engineering non‐ribosomal peptide synthetase proteins: a potential new source of pharmacological agents

Many important pharmaceutical agents, including vancomycin, bleomycin, cyclosporin, and several antibiotics, are produced by non‐ribosomal peptide synthetase (NRPS) enzymes in microorganisms. The NRPS pathway produces an extensive library of products using multienzyme complexes acting in an assembly‐line fashion. Engineering an NRPS system to produce an even greater variety of products, some of which may also have beneficial therapeutic value, would be an enormous advantage. Several approaches have been successful in generating novel NRPS products: mutational biosynthesis during which nonnatural substrates are fed to an organism; domain and module swapping between different species to generate hybrid enzymes; and rational site‐directed mutagenesis, based either on phylogeny or computational prediction, intended to switch substrate specificity and produce altered products. This review will highlight the progress in these areas and describe research in the future that will extend the capacity for re‐engineering NRPS systems. Drug Dev. Res. 66:9–18, 2006. © 2006 Wiley‐Liss, Inc.     

含谷氨酰胺双肽肠外营养在门腔分流术后应用的临床研究

目的　探讨门腔分流术后病人给予含丙氨酰 谷氨酰胺双肽 (Ala GLN)肠外营养 (PN)的安全性 ;观察其营养支持的效果 ,及对肠道通透性的影响。方法　 16例病人随机分为两组。对照组(n =7)接受不含GLN的PN ;实验组 (n =9)接受含Ala GLN双肽的PN。两组自术后第 1天起给予等氮、等热量的PN共 7d ,于PN前后分别测定血清前白蛋白、氮平衡变化、血清GLN浓度、血氨、尿乳果糖 /甘露醇排泄率比值 (L/Mratio)、生化和临床指标的变化。结果　对照组术后血清GLN水平比术前显著降低 ,术后实验组GLN水平 (5 77± 4 2 ) μmol/L显著 (P =0 0 0 9)高于对照组术后水平 (499± 6 1)μmol/L ;两组术前的L/M比率均明显高于国人正常水平 ,术后对照组L/M水平 (0 0 95± 0 0 34)显著 (P=0 0 4 5 )高于实验组 (0 0 6 4± 0 0 2 3) ;两组累积氮平衡无显著性差异 ,但实验组第 5～ 7天期间氮平衡要明显优于对照组 ,实验组第 5天氮平衡 (- 15 3± 4 6 9)mg·kg-1·d-1显著 (P =0 0 4 3)好于对照组 (-92 7± 90 5 )mg·kg-1·d-1;对照组术后血清前白蛋白水平较术前显著下降 ,实验组术后血清前白蛋白水平 (0 2 6 9± 0 0 37)g/L显著 (P =0 0 0 1)高于对照组 (0 199± 0 0 2 7)g/L ;两组术后血氨水平相比无统计学意义 ;生     

谷氨酰胺和生长激素对短肠综合征患者肠道代偿作用

目的探讨谷氨酰胺和生长激素对短肠综合征(SBS)患者的肠道代偿作用。方法26例短肠综合征患者残余小肠长度为0～100(中位数42.5)cm,手术后接受肠外营养(PN)支持3-52个月,联合应用生长激素(GH)(0.10±0.06)mg·kg-1·d-1和谷氨酰胺(GLN)(0.30±0.17)g·kg-1·d-1进行肠道促代偿治疗。结果26例接受GH加GLN治疗的SBS患者,其中9例(34.6%)治疗后近期内完全摆脱PN;8例(30.8%)经治疗后明显减少了PN用量,从每周需要PN(6.0±1.0)d下降至(4.2±1.0)d,每周PN需要量从(13.6±5.2)L降至(8.2±3.3)L;9例(34.6%)在治疗后仍依赖PN维持。结论经过合适的营养支持和肠道促代偿治疗,大多数短肠综合征患者残留肠道能充分代偿,完全摆脱PN或减少PN用量,长期健康生存。     

口服谷氨酰胺颗粒对烧创伤患者的疗效及安全性分析

目的观察口服谷氨酰胺(Gln)颗粒对烧(创)伤及大手术患者的疗效及可能发生的不良反应.方法采用随机双盲、安慰剂对照法,将受试患者分为Gln组和对照组,每组60例,两组患者采用等氮、等热量的营养支持.Gln组口服或管饲Gln 0.5 g·kg-1·d-1,对照组使用同等剂量的安慰剂甘氨酸,疗程均为7 d.比较用药前后两组患者肠黏膜屏障功能、蛋白代谢、免疫功能、肝和肾功能的变化及不良反应等. 结果伤后两组患者血浆Gln浓度明显低于正常值,而血浆二胺氧化酶(DAO)活性、内毒素含量、肠黏膜通透性[尿乳果糖/甘露醇(L/M)]及尿氮排量均明显增高;但Gln组用药7 d后血浆Gln浓度与用药前比较增加38.04%(P＜0.01).Gln组血浆前白蛋白、转铁蛋白及白细胞介素2(IL-2)含量均显著高于对照组(P＜0.01),升幅分别为21.19%、51.11%、57.54%.血浆DAO活性、L/M比值、内毒素含量及尿氮排量明显低于对照组,降幅分别为47.26%、52.18%、22.22%、27.78%(P＜0.05或0.01).两组患者的血浆总蛋白、白蛋白、血尿常规及肝、肾功能在用约前后变化不明显(P＞0.05).用药后有少数患者出现轻微不良反应如恶心、腹泻和便秘等,2～3 d后自行缓解,两组间比较,差异无显著性意义(P＞0.05).结论口服Gln能显著提高患者血浆Gln浓度,明显减轻伤后肠黏膜受损程度,并能促进机体蛋白合成,降低蛋白分解,提高机体免疫功能,且临床应用无明显不良反应.     

萘普生对大鼠着床期宫内PGF_(2α)含量及宫内节育器抗生育作用的影响

本文测定了对照组及两个萘普生(前列腺素合成酶抑制剂)处理组大鼠着床期宫内PGF2α的含量。结果表明,对照组、萘普生低剂量组(2mg/kg体重)和高剂量组(20mg/kg体重)的PGF2α含量分别为6.71±0.93、2.19±0.34和1.01±0.18ng/100g组织(三组间P<0.01)。同时,还观察到在本实验条件下,萘普生无明显干扰节育器抗生育作用,药物本身亦未呈现显著抗生育活性。     

Reversible shifts in the Ca2+-dependent release of aspartate and glutamate from hippocampal slices with changing glucose concentrations

It is known that low glucose concentrations increase the aspartate and decrease the glutamate content of brain tissue both in vivo and in vitro. To see whether these changes occur in the transmitter compartment or not, the release of aspartate and glutamate evoked by electrical-field stimulation or by high K+ was followed in slices of rat hippocampus superfused with 5 or 0.2 mM glucose. Superfusion with 0.2 mM glucose increased the evoked release of aspartate about ten times and that of glutamate about threefold. This shift in the ratio of aspartate to glutamate released was accompanied by a similar increase in the relative amount of aspartate contained in the slices. The high evoked release of aspartate and glutamate was well maintained, provided 0.5 mM glutamine was added to the medium. Changing the concentration of glucose after the first period of stimulation rapidly altered the relative amounts of aspartate and glutamate released but not the enhanced release of glutamate. The large evoked release of both aspartate and glutamate in 0.2 mM glucose was almost entirely Ca2+-dependent. The relative amounts of aspartate and glutamate released by 50 mM K+ also changed when the glucose concentration was reduced. Results suggest two effects of low glucose concentrations: an increase in the overflow of synaptically released glutamate due to a decreased uptake and an increase in the proportion of aspartate to glutamate formed and released from the transmitter pool. These observations are consistent with the interpretation that these two transmitters can be released in different proportions from the same terminals.     

Glutamine and Other Amino Acid Losses During Continuous Venovenous Hemodiafiltration

Abstract: Serum amino grams and daily losses of glutamine (Gin) and other amino acids (AAs) into diafiltrate were measured during the first 5 days of continuous venovenous hemodiafiltration (CVVHDF) in 6 ICU patients with acute renal failure (ARF). Four patients had ARF as a part of multiple organ failure (MOF) of septic origin, and 2 patients had isolated ARF because of primary renal disease. During the study, all the patients received defined total parenteral nutrition (TPN). The mean daily AA losses into dialysate were relatively low (0.61 ± 0.1 g N ) and reached 4.5% of the daily AA substitution. Gln represented 32.7 ± 5.9% of the total AA losses (0.19 ± 0.04 g N ). Serum levels of Gin (p = 0.002) and of most other AAs were significantly lower in the patients than in the control subjects (AA analysis in 16 healthy volunteers). Phenylalanine (Phe) was the only AA that was increased significantly (p < 0.01) in the patients. The mean patient serum concentrations of Phe and tyrosine were significantly higher (p < 0.03) than the correspondent concentrations in dialysate, but the lysine concentration was higher in dialysate (p < 0.03). The serum and dialysate concentrations of other AAs did not differ. Gin in serum decreased significantly (p < 0.03) on the second day of CVVHDF but returned to the baseline levels subsequently. Serum concentrations of Phe increased on the second day of CVVHDF (p < 0.05). Serum concentrations of other AAs remained stable during the whole study. We conclude that Gin losses into dialysate during CVVHDF are relatively low, but CVVHDF itself may induce changes in Gin metabolism and distribution that are reflected by a decrease of serum Gin levels at the institution of this treatment. Therefore, the need for Gin supplementation in ICU patients is even greater in the first days of CVVHDF.     

Localization of glial cell antigens in the brains of young normal mice and the dysmyelinating mutant mice, jimpy and shiverer

Tissue sections from the brains of normal, jimpy, and shiverer mice were immunostained by the peroxidase antiperoxidase method for carbonic anhydrase (CA) and the putative astrocytic "markers" glutamine synthetase (GS) and glial fibrillary acidic protein (GFAP). The cells in normal gray matter that immunostained with anti-CA and anti-GS were similar to one another in size and process elaboration. In the normal gray matter there were relatively few GFAP-positive astrocytes. When present, these cells resembled the CA- and GS-positive cells; however, the GFAP appeared to be concentrated in the astroglial processes, as distinguished from the cell bodies. Glial cell processes, immunostained for CA or GS, surrounded blood vessels and unstained neurons in the normal gray matter. The glial cells in shiverer gray matter were similar to those in the normal gray matter. When stained for GS or GFAP, the glial cells in the jimpy gray matter appeared to be somewhat hypertrophied, and when the glial cells in this mutant were stained for CA, the nuclei appeared to be swollen. It was concluded that some of the CA-positive cells in the gray matter of the normal and of each mutant mouse brain could be astrocytes. The patterns of immunostaining in the white matter emphasized the different complements of glial cells in the mutants. In the normal and shiverer mouse corpus callosum, CA, in particular, was detected only in the oligodendrocytes, their processes, and myelin. However, the data concerning the jimpy mouse suggested that the few CA-positive cells in the corpus callosum of that mutant could be astrocytes.     

Identification of 16 novel mutations in the argininosuccinate synthetase gene and genotype-phenotype correlation in 38 classical citrullinemia patients

Classical citrullinemia (CTLN1), a rare autosomal recessive disorder, is caused by mutations of the argininosuccinate synthetase (ASS) gene, localized on chromosome 9q34.1. ASS functions as a rate-limiting enzyme in the urea cycle. Previously, we identified 32 mutations in the ASS gene of CTLN1 patients mainly in Japan and the United States, and to date 34 different mutations have been described in 50 families worldwide. In the present study, we report ASS mutations detected in 35 additional CTLN1 families from 11 countries. By analyzing the entire coding sequence and the intron-exon boundaries of the ASS gene using RT-PCR and/or genomic DNA-PCR, we have identified 16 novel mutations (two different 1-bp deletions, a 67-bp insertion, and 13 missense) and have detected 12 known mutations. Altogether, 50 different mutations (seven deletion, three splice site, one duplication, two nonsense, and 37 missense) in 85 CTLN1 families were identified. On the basis of primary sequence comparisons with the crystal structure of E. coli ASS protein, it may be concluded that any of the 37 missense mutations found at 30 different positions led to structural and functional impairments of the human ASS protein. It has been found that three mutations are particularly frequent: IVS6-2A>G in 23 families (Japan: 20 and Korea: three), G390R in 18 families (Turkey: six, U.S.: five, Spain: three, Israel: one, Austria: one, Canada: one, and Bolivia: one), and R304W in 10 families (Japan: nine and Turkey: one). Most mutations of the ASS gene are "private" and are distributed throughout the gene, except for exons 5 and 12-14. It seems that the clinical course of the patients with truncated mutations or the G390R mutation is early-onset/severe. The phenotype of the patients with certain missense mutations (G362V or W179R) is more late-onset/mild. Eight patients with R86H, A118T, R265H, or K310R mutations were adult/late-onset and four of them showed severe symptoms during pregnancy or postpartum. However, it is still difficult to prove the genotype-phenotype correlation, because many patients were compound heterozygotes (with two different mutations), lived in different environments at the time of diagnosis, and/or had several treatment regimes or various knowledge of the disease.