甘氨酸及其小肽配合物的pH电位法研究

利用ｐＨ 电位法研究了甘氨酸及其二、三肽与锌、铜元素的配位作用，测定了相应的配合稳定常数，结果表明，氨基酸和二、三肽的配合行为不同，而小肽之间配位作用基本相似．ｐＨ 电位法研究还表明，铜与肽的配合过程中存在着明显的晶体场稳定化能效应，表现在配合滴定过程中出现特征颜色变化（双缩脲反应）．     

亚硝酸盐替代物--组氨酸发色作用的研究

采用组氨酸与血红蛋白形成配位复合物，替代亚硝酸钠的发色作用，研究了pH对配合物紫外吸收的影响，计算出配位平衡常数β，并通过不同温度下测定β值，求出反应的标准摩尔焓和标准摩尔熵，表明配位反应是熵、焓降低的过程。     

甘氨酸螯合铁的合成工艺

以氯化亚铁和甘氨酸为原料,研究了甘氨酸螯合铁的合成工艺条件.结果表明,pH值、配位比以及抗氧化剂用量对产品组成和得率有很大影响.确定了螯合的最适条件为:pH值为5.5、配位比为4∶1.采用有机溶剂萃取法,使甘氨酸螯合铁在无水乙醇中以沉淀的方式析出,实现甘氨酸螯合铁与无机铁的分离.讨论了萃取时有机溶剂用量对产品得率的影响,在无水乙醇与滤液的体积比为9∶1时,亚铁得率最高.     

对氯偶氮安替比林分光光度法测定茶叶中的铜

作者研究了铜(Ⅱ)与对氯偶氮安替比林的显色反应,实验结果表明,在pH值为4.0的缓冲溶液中,铜与对氯偶氮安替比林形成稳定的蓝色配合物,最大吸收波长为632nm,表观摩尔吸光系数为3.78×104L/(mol·cm).铜质量浓度在0～1.2μg/mL范围内符合比耳定律,该方法可用于茶叶样品中铜(Ⅱ)的测定.     

超滤处理对大豆肽体外免疫功能的影响

考察了不同pH值（4.0、7.0、9.0）条件下采用不同截留相对分子质量（MWCO）的8000复合膜（醋酸纤维＋聚砜）和5000 PES（聚醚砜）的超滤膜对大豆肽处理前后对小鼠体外免疫功能的影响。通过体外培养白细胞实验,比较了大豆肽超滤处理前后对小鼠腹腔巨噬细胞吞噬功能和脾细胞增殖能力的影响。结果表明,所有大豆肽均能提高小鼠腹腔巨噬细胞的吞噬能力,促进小鼠脾淋巴细胞增殖,而经过超滤处理后的大豆肽免疫功能有所提高,且以pH4.0条件下MWCO为5000超滤膜处理后所得的大豆肽活性最强。     

盐对勾兑牛奶酒体系稳定性的影响

试验了不同浓度的柠檬酸三钠对于勾兑牛奶酒体系的影响,结果表明随着柠檬酸三钠浓度的增大,勾兑牛奶酒体系的pH值和粘度也随之增大,当柠檬酸三钠的浓度由0.002mol/L增大到0.02mol/L,酒精质量分数大于20%时,其体系的pH值表现出了几乎相同的增加值;而对所有体系来讲,随着酒精质量分数的增大,粘度的增加值却越来越小.试验结果还发现,加入0.008mol/L柠檬酸三钠能够使得牛奶蛋白在乙醇存在下达到最好的稳定效果.     

pH值对单克隆抗体法检测大便潜血的影响

目的:探讨不同pH值溶液对单克隆抗体法检测结果的影响.方法:在pH为0～14的不同pH值水溶液中,用单克隆抗体法对大便进行潜血检测,观察不同pH值溶液对单克隆抗体法的影响.结果:溶液pH值对单克隆抗体法检测大便潜血有影响,出现了假阳性.结论:单克隆抗体法检测大便潜血简单、快速、具有很高的特异性和灵敏度,不受饮食和药物的限制,但它可受溶液pH值的影响.     

温度、pH值、盐度交互作用优化福氏志贺氏菌F2b培养条件

研究温度、pH值、盐度3个因素交互作用下食源性致病微生物福氏志贺氏菌F2b的最优培养条件.在温度、pH值、盐度单因素试验的基础上,应用 Box-Behnken中心组合试验原理,设计三因素交互作用试验.以温度、pH值、盐度为响应因子,以菌液的OD550为响应值,采用响应面法处理试验数据.结果表明,在所选的因素水平范围内,温度、pH值对F2b生长影响显著,温度、pH值之间交互作用显著.获得志贺氏菌F2b的最佳生长条件为温度35.8 ℃,pH值7.7,盐度0.76 g/dL.经过验证,实测值和预测值之间偏差为1.1%,表明响应面法优化F2b培养条件真实、快速、有效.     

皮下CO2充气对腔镜下甲状腺手术动脉血气的影响

目的观察颈部皮下CO2充气对腔镜下甲状腺手术动脉血气的影响. 方法 2002年6月～2003年3月7例气管插管全麻下行腔镜下甲状腺手术,皮下充入CO2压力6 mm Hg,监测动脉血pH、PaCO2变化. 结果充气后5 min PaCO2升高,pH值下降,15 min PaCO2达到高峰(44.33±0.97) mm Hg,pH值最低(7.36±0.02),充气后各时间段PaCO2 和pH与充气前比有显著差异(P<0.05);30 min后PaCO2开始下降,pH值上升,1 h PaCO2、pH值达到稳定水平;放气后PaCO2、pH值接近充气前水平. 结论皮下CO2充气对腔镜下甲状腺手术动脉血PaCO2、pH值有影响,但仍在正常范围.     

188Re标记小剂量奥曲肽方法学及其在小鼠体内分布的研究

目的建立188Re标记小剂量奥曲肽(octreotide)的方法,观察其在小鼠体内的生物学分布.方法 SnCl2·2H2O的用量为50～1 600μg,奥曲肽的用量为10、20或30μg,乙酸缓冲液的pH值从4.0至6.0,反应体系的温度为室温、60、80或100℃,淋洗液体积从0.05至0.20 ml,测定标记物的标记率及其在体外的稳定性.将标记物经小鼠尾静脉注射,于0.5、1、2、4、24 h取血液及主要脏器测量其放射性计数率值.结果 188Re直接法标记小剂量奥曲肽的最佳条件葡庚糖酸钠(0.3 mmol/L)0.1 ml,SnCl2·2H2O(16 g/L)0.05 ml,乙酸缓冲液(pH=5)0.1 ml,奥曲肽(0.1 g/L)0.1 ml,通氮气震荡反应1 h,再加入新鲜188Re淋洗液0.1ml,100℃水浴30 min,188Re-奥曲肽标记率可达到(95.3±1.8)%,室温下放置24 h放化纯为(89.6±2.5)%.188Re-奥曲肽在正常小鼠体内主要分布于肝脏、肾脏及肠道.结论研究建立的188Re标记奥曲肽操作简便,标记率高,体外稳定性好,无需进一步纯化,奥曲肽用量较小,预期能提高靶向定位质量,188Re-奥曲肽在小鼠体内主要被肠道、肝脏、肾脏等器官摄取,血液清除快.     

Mimics of copper proteins: structural and functional aspects

The importance of copper as an essential element can be estimated by the wide range of copper proteins and enzymes playing different roles in biological systems. In the last decades many bioinorganic studies were developed on mimetic complexes of copper-dependent proteins, in order to verify the interrelations between structural and functional properties of active copper centers. Among the most studied copper ion ligand, diimine compounds have deserved special attention due their flexibility, facility of preparation, and ability to stabilize both oxidation states of this metal. In our laboratory, we have been investigating some Schiff base copper complexes as mimics of different proteins, with emphasis on functional aspects, trying to elucidate mechanisms of reaction, based on proposed intermediary species, in addition to molecular shapes. Particularly, mimics of the copper-zinc superoxide dismutase, and of monooxigenases and oxidases exhibiting dicopper sites are discussed in this work.     

Urinary copper excretion in type 2 diabetic patients with nephropathy

BACKGROUND/AIMS: The aim of this study was to examine the relationship between the degree of urinary copper excretion and stages of diabetic nephropathy. METHODS: Copper, ceruloplasmin and albumin concentrations were measured in serum and urine samples from 41 type 2 diabetic outpatients with different stages of nephropathy and from 10 healthy controls. The copper/albumin and copper/ceruloplasmin ratios in serum and urine were determined. Furthermore, we examined whether free copper ions are dissociated from ceruloplasmin under various pH conditions. RESULTS: Urinary copper concentrations significantly increased only in macroalbuminuric patients. The copper/ceruloplasmin and copper/albumin ratios in urine were consistently greater than those in serum which were not different between patients and healthy controls except the copper/albumin ratio in macroalbuminuric patients. The ratios in urine decreased in parallel with the progression of nephropathy. Copper was found to be released from ceruloplasmin under acidic conditions. CONCLUSION: Urinary copper excretion in healthy controls may be the result of dissociation from the albumin-copper complex of serum during its passage through the kidney. In diabetic patients with advanced nephropathy, urinary copper excretion may be due to dissociations from both copper-albumin and ceruloplasmin-copper complexes filtered through the damaged glomerulus. Overloading of urinary copper to damaged renal tubules may play some roles in the progression of nephropathy in patients with advanced nephropathy.     

The effect of ramipril, a new angiotensin-converting enzyme inhibitor on cortical nephron flow and effective renal plasma flow in patients with essential hypertension

A placebo-controlled study of Ramipril on total and intrarenal flow distribution was carried out in 7 patients with essential hypertension. Cortical nephron flow was measured using radiolabelled tubular secreted radiopharmaceuticals 123I orthoidohippurate or 99mTc mercaptoacetyl triglycine by the transit time distribution technique. Both systolic and diastolic blood pressure were reduced significantly by Ramipril without significant changes in an index of cardiac output or in effective renal plasma flow. Cortical nephron flow increased from 207 +/- 7 to 257 +/- 21 ml/min (mean +/- SEM) p less than 0.05 and the percentage of flow to cortical nephrons increased by 6% (p = 0.05). Ramipril corrects the reduced cortical nephron flow found in essential hypertension.     

Glycine and transurethral resection

Fifty patients undergoing transurethral resection of the prostate were studied for evidence of glycine absorption and haemodilution. Plasma glycine levels increased substantially in nine patients and, in five, calculated irrigant fluid absorption ranged from 619-1582 ml; another patient had absorbed 1360 ml fluid with only a small rise in plasma glycine. Two illustrative case histories are presented. The role of glycine as an inhibitory neurotransmitter is discussed and the possibility of toxic mechanisms other than dilutional hyponatraemia is mentioned. Intravenous diuretics, hypertonic saline, and perhaps calcium salts, are recommended for the overt transurethral resection syndrome.     

Glycine irrigation and urinary oxalate excretion

The short-term effect of glycine supplementation on urinary oxalate excretion was studied. An intravenous infusion of 1 litre of a solution of 2.2% glycine, 1.5% glycine + 1% ethanol or 5% mannitol (control) was given on 13 occasions to 5 healthy volunteers. Glycine irrigation was used in 9 patients undergoing transurethral prostatic resection and the absorption of irrigant was measured volumetrically (range 0-2.71). The results suggest that glycine irrigation in transurethral prostatic surgery does not raise the urinary oxalate level in the early post-operative period.     

Glycine solution as an irrigating agent during transurethral prostatic resection. Glycine concentrations in blood plasma

In 17 men undergoing transurethral resection of the prostate (TURP), an isosmotic solution of 2.2% glycine was used for irrigation. The plasma glycine concentration was determined before and immediately after TURP and 2, 6, 24 and 48 hours later. The serum concentrations of sodium, albumin and prostatic acid phosphatase protein (PAP) were used as indicators of fluid absorption. Calculation of the absorbed fluid volume was based on the plasma concentration of glycine, and the disappearance rate of glycine from plasma was estimated. The mean disappearance rate (T 1/2) was 85 min, which was midway between previously observed rates for sorbitol and mannitol. The observed plasma glycine increase after TURP correlated well with fall in serum sodium and rise in serum PAP, with the blood loss during and up to 15 min after TURP, and also with the weight of the resected tissue. The plasma glycine level, highest immediately after TURP, normalized 24-48 hours postoperatively. No signs of ammonia intoxication or marked serum urea increase were seen in these patients, although some had very high plasma glycine values after TURP (mean 10.2, maximum 23 mmol/l) as compared with the preoperative levels (mean 0.2 mmol/l). There was some increase of plasma serine (a normal metabolite of glycine) after TURP. The authors conclude that the irrigating fluid should have a minimal concentration of glycine, near to the level of haemolysis onset, to minimize the plasma dilution effects, including hyponatraemia, and the appearance of metabolites when the irrigating fluid is absorbed.     

Glycine prevents the induction of apoptosis attributed to mesenteric ischemia/reperfusion injury in a rat model

PURPOSE: We have previously demonstrated that glycine has a protective effect in mesenteric ischemia/reperfusion (I/R) injury. The purpose of this study was to elucidate the molecular mechanisms of the cytoprotective action of glycine. Because oxidative stress in I/R injury can lead to apoptosis, we examined the role of glycine in modulating the apoptotic signals in a rat mesenteric I/R injury model. METHODS: Twenty-four anesthetized male Sprague-Dawley rats were subjected to 1 hour of mesenteric ischemia followed by 2 hours of reperfusion. Control animals (n=6) received normal saline intravenously at the rate of 0.01 mL/g/h during the ischemia and reperfusion period. Treated animals divided in 3 groups (n=6 in each) received glycine at a dose of either 0.5, 0.75, or 1.0 mg/g, infused at the rate of 0.01 mL/g/h during the reperfusion period. Animals were killed at the end of the experiment, and proximal, middle, and distal segments of the small bowel were harvested for histopathology, TUNEL assay, and immunohistochemistry. Expression of apoptosis-related molecules, bcl-2, bax, caspase-3, death receptor, Fas, and death substrate, poly (ADP-ribose) polymerase (PARP) were studied. RESULTS: In glycine-treated animals, the middle and distal segments of the small intestine were well- preserved and showed better histologic grade and morphometric parameters as compared with saline controls (P<.05) in a dose-independent manner. There was increased apoptosis in saline controls as compared to the treated group (P<.01). Pro-apoptotic bax and caspase-3 were downregulated, whereas bcl-2 was upregulated in the glycine-treated animals (P<.02). Increased expression of death receptors and cleavage of PARP was observed in saline controls as compared to treated groups (P<.05). No significant differences were noted between the proximal bowel segments of treated and control animals. CONCLUSIONS: These data support the concept that I/R causes formation of death- inducing signal complexes, which may activate the sequential cleavage of caspases and death substrates. We have demonstrated that one of the mechanisms of the protective effect of glycine is the downregulation of the death-inducing signals and abrogation of the apoptotic cascade in this I/R injury model.     

Glutathione and Glycine in Acute Renal Failure

Background. Ochratoxin A (OTA) is a nephrotoxic metabolite occurring in foodstuffs. In the last decade, OTA‐induced nephropathy in man and animals have been confirmed by previous literature. The correlation between OTA and the severity of CRI and nephrotic syndrome was also researched. Therefore, this study was designed to determine whether OTA also played an important role in renal insufficiency of patients with chronic renal diseases in Taiwan. Methods. The patients in this study were divided into nonnephrotic syndrome and nephrotic syndrome groups, first, to look for the relation between urine protein and OTA. And then these patients were also divided into six groups: (I) patients with chronic glomerulonephritis; (II) patients with chronic interstitial nephritis; (III) patients with diabetes mellitus; (IV) patients with hypertension; (V) patients with other diseases; (VI) patients with unknown reasons. For all groups, laboratory evaluation of kidney such as serum creatinine, urinary creatinine, creatinine clear rate, urinary protein, and urinary analysis were carried out coupled with determination of ochratoxin A level in urine. Results. Higher levels of OTA were found in patients with nephrotic syndrome. There was a significantly positive correlation (P < 0.001) between 24‐hr OTA and 24‐hr urine protein. On the other hand, the mean excretion of OTA in DM group (group III) was found significantly higher compared to the other groups (P < 0.05). Distinct differences (P < 0.01) were found especially when DM group was compared with patients with chronic glomerulonephritis (group I; P = 0.0019), patients with chronic interstitial nephritis (group II; P = 0.0032) and patients with hypertension (group IV; P = 0.0062). Conclusion. The results could lead to the conclusion that OTA could play an important role in proteinuria of patients with chronic renal diseases in Taiwan. And OTA may play a role in diabetes patients with nephropathy. Further longitudinal study is needed to clarify the role of OTA in diabetic nephropathy.     

Vibrational spectra of some phosphate salts amorphous to X-ray diffraction

Complete infrared and Raman spectral data are presented for a number of phosphate salts amorphous to X-ray and electron diffraction and spherical in morphology under the electron microscope. These were amorphous calcium, magnesium and copper (II) orthophosphate; amorphous calcium carbonate orthophosphate; and amorphous calcium pyrophosphate. The average coordination (bond arrangement) in these materials was non-isotropic, i.e., perturbed relative to that in a completely symmetric milieu. The data suggest that these bond arrangements do not correspond to phosphate crystal lattices. Two spatial configurations are possible for these amorphous salts: 1) a random packing of unit coordination structures having constant composition and fixed bonding relationships; or 2) a random network of coordination complexes whose exact composition and structure can vary from site to site. Cationic constituents strongly influenced bonding and water molecules appeared to contribute to coordination structure. In amorphous carbonate phosphates, regions rich in either calciumphosphate or calcium-carbonate bonding appeared to be contiguous with areas exhibiting mixed ion coordination.