感染食蟹猴疟原虫的大劣按蚊血淋巴和胃水解物氨基酸分析

大劣按蚊感染食蟹猴疟原虫B株后第10d,血淋巴内的蛋氨酸、异亮氨酸、亮氨酸、鸟氨酸、赖氨酸含量均较对照组低。第9d蚊胃水解物分析结果表明,感染蚊胃中的多数氨基酸含量增加,其中缬氨酸、蛋氨酸、酪氨酸的含量是对照组3倍以上,氨基酸的总量比对照组高70％以上。     

斯氏按蚊血淋巴游离氨基酸和蛋白的研究

用氨基酸自动分析仪测定斯氏按蚊血淋巴游离氨基酸的变化,用紫外吸收差法测定其蛋白浓度。感染约氏疟原虫蚊与正常蚊相比,吸血后第4d,6种氨基酸含量降低,5种氨基酸含量增加;吸血后第7d,4种氨基酸含量降低,7种氨基酸含量增加;吸血后第11d,9种氨基酸含量降低,4种氨基酸含量增加。感染蚊血淋巴蛋白浓度均高于同期正常蚊。     

三种蚊虫血淋巴游离氨基酸的研究

用离心法收集雌蚊血淋巴,用氨基酸自动分析仪检测血淋巴游离氨基酸的组成,并对三种蚊虫作了比较。羽化时,中华按蚊分别与斯氏按蚊和白纹伊蚊相比,各有14种氨基酸有显著性差异;斯氏按蚊与白纹伊蚊相比,有12种氨基酸有显著性差异。吸鼠血后第4d,中华按蚊与斯氏按蚊和白纹伊蚊相比,分别有15和16种氨基酸有显著性差异;斯氏按蚊与白纹伊蚊相比,有14种氨基酸有显著性差异。白纹伊蚊吸鼠血后第4d与吸鸡血后第4d相比,有17种氨基酸有显著性差异。这些差异是由蚊种和脊推动物宿主的不同引起的。     

Modification of the effects of blood on amino acid metabolism by intravenous isoleucine

The absence of isoleucine in the hemoglobin molecule has been suggested to contribute to increased urea production after a blood meal. To unravel the underlying mechanism, the effects of isoleucine infusion after blood ingestion in the healthy pig were studied. The isoleucine dose was chosen to induce an arterial isoleucine increase comparable to those observed for leucine or valine after blood ingestion. For the experiments, 10 female overnight-fasted pigs (20-25 kg) received 250 mL bovine erythrocytes intragastrically 1 week after catheter implantation for measuring hepatic, splanchnic, portal-drained viscera, and hindquarter fluxes of amino acids, urea, and ammonia. After the administration of erythrocytes, isoleucine or saline was administered i.v. for 6 hours. The data obtained show that the increase in arterial levels of urea and almost all amino acids was significantly greater in the control group (P less than 0.001) than in the isoleucine group. The net efflux of nearly all amino acids by the portal-drained viscera increased significantly less (P less than 0.001) in the isoleucine group. The liver uptake of amino acids increased after the blood meal, but the difference was not significant except for glutamine (P less than 0.001). Hindquarter amino acid net influx increased marginally. Splanchnic urea production increased more in the control group than in the isoleucine group (P less than 0.05). The data strongly suggest that i.v. administration of isoleucine enhanced the biological value of a blood meal, possibly by promoting amino acid retention in the portal drained viscera.     

Serum amino acids in hepatic encephalopathy--effects of branched chain amino acid infusion on serum aminogram

Encephalopathic patients with cirrhosis of the liver consistently showed elevated levels of the aromatic amino acids, phenylalanine, tyrosine and free tryptophan as well as methionine in serum, whereas levels of the branched chain amino acids, valine, leucine and isoleucine, were depressed. Comatose patients with fulminant hepatitis had markedly elevated levels of all amino acids, the results being greatly different from those of cirrhotic patients. Molar ratios of (valine + leucine + isoleucine)/(phenylalanine + tyrosine) decreased both in cirrhotics with and without encephalopathy and in cases with fulminant hepatitis. Infusion of a commercially available L-amino acid solution in a cirrhotic patient induced a strikingly abnormal aminogram documented in hepatic encephalopathy. Therefore, effects of branched chain amino acid infusion on the deranged amino acid pattern were primarily studied for the purpose of improvement in hepatic encephalopathy by normalization of serum amino acid patterns. Elevated levels of the aromatic amino acids and methionine could be apparently depressed in a cirrhotic patient by this type of infusion but not in a case of fulminant hepatitis probably because of the poor utilization of these amino acids in severely impaired liver.     

Reduction of large neutral amino acid concentrations in plasma and CSF of patients with maple syrup urine disease during crises

Neurological dysfunction is common in patients with maple syrup urine disease (MSUD). However, the mechanisms underlying the neuropathology of this disorder are poorly understood. We determined the concentrations of all amino acids in plasma of patients with MSUD during crises (with severe CNS symptoms) and after recovery in the hope of detecting possible alterations of these levels during metabolic decompensation. Blood samples obtained from 11 children with MSUD aged 1 month to 7 years and from 10 age-matched controls (5 months to 6 years) with no evidence of metabolic disease were examined for their amino acid content by high-performance liquid chromatography. We observed that leucine, isoleucine and valine concentrations were respectively 30, 9 and 3 times higher than normal values, whereas the concentrations of the large neutral amino acids (LNAA) phenylalanine, tyrosine, tryptophan and methionine were significantly lower during metabolic decompensation as compared to the controls. In addition, concentrations of leucine, but not of valine or isoleucine, were inversely related to the LNAA concentrations in plasma. The concentrations of these amino acids in plasma returned to normal values when patients were clinically well. CSF amino acid concentrations also showed decreased amounts of LNAA and increased concentrations of branched-chain amino acids. It is possible that the decrease in plasma concentrations of LNAA may lead to a deficit of these essential amino acids in the brain as well as of their products such as proteins and neurotransmitters, a fact that might be related to the neurological dysfunction of MSUD.     

Effect of different protein diets on the distribution of amino acids in plasma, liver and brain in the rat.

The distribution of amino acids between plasma, liver and brain was studied in adult male rats, fed a diet containing 8.7, 17 (control animals), 32 and 51% of protein during 15 days. The caloric intake was nearly equal in all groups. The highest food intake was observed in the animals on the low protein diet. Changes in plasma amino acids were variable. In contrast to the behavior of most amino acids in plasma, the branched chain amino acids were highest in the animals fed the 51% protein diet. Despite the low protein intake in the animals fed a 8.7% protein diet, the concentration of serine, glutamic acid, glutamine, glycine, alanine, methionine, isoleucine, leucine, phenylalanine and ornithine were significantly higher compared to control animals, whereas in those receiving a high protein diet, valine, leucine, tyrosine, tryptophan and histidine increased in relation to the increased protein and amino acid intake. The plasma amino acid patterns are not greatly influenced by the amino acid distribution in the food and the amount ingested. Alanine aminotransferase, aspartate aminotransferase, glutamate dehydrogenase and cholinesterase showed a two- to fivefold increased activity in the liver of animals consuming a high protein diet. In the brain, the concentration of valine, leucine, isoleucine, phenylalanine and tyrosine in animals receiving the low protein diet was higher than in controls and increased further with increasing protein content of the diet. Glutamine was increased in all dietary groups. The predicted influx of amino acids showed increasing influx rates in dependence of the plasma amino acid concentration. The entry of tyrosine and tryptophan and their brain concentration was inversely proportional to the protein content of the diet. In the present study which considers long-term adaptation to an increasing protein and amino acid intake in comparison to a balanced control protein diet, the levels of the indispensable amino acids were maintained within narrow limits in the brain and liver. The results indicate that inspite of a variable protein intake, the body tends to keep organ amino acids in relatively narrow limits favoring in this way amino acid homeostasis.     

A study of plasma free amino acid levels. V. Correlations among the amino acids and between amino acids and some other blood constituents

Possible relationships among the amino acids were examined by determining the correlation between their fasting plasma levels in 136 children and 193 adults. Leucine and isoleucine values were the most highly correlated. Threonine, serine, and glycine were significantly related in boys, girls, and men, but there was no correlation between threonine and glycine levels in women. A group of 11 amino acids appeared to be highly interrelated: These were alanine, asparagine, glutamine, valine, isoleucine, leucine, methionine, tyrosine, phenylalanine, proline, and lysine. Possible correlations between the individual amino acid levels and hemoglobin, blood glucose, plasma cholesterol, and uric acid levels were also examined. There were no highly significant relationships between amino acid levels and the levels of any of them.     

嗜人按蚊血淋巴微量元素与常量元素的研究

应用ＩＣＡＰ－９０００型等离子原子发射光谱仪检测嗜人按蚊血淋巴的元素组成，检出铁、锌、铜、锰、铬、钼、钴、镍、钒、锶、硼、铝、钡、锆、铅、镉、镓、锂等１８种微量元素及钙、镁、钾、钠、磷、硫等６种常量元素。初羽化雌蚊血淋巴中６种常量元素含量均比吸血后５ｄ蚊为高，且有非常显著性差异；微量元素铁的含量也较高，有非常显著性差异，锌和铝含量则较低，有非常显著性差异和显著性差异。比较嗜人按蚊和中华按蚊血淋巴中１６种元素含量，显示初羽化雌蚊和吸血后５ｄ的蚊血淋巴中分别为１４种和１３种元素，有非常显著性差异。嗜人按蚊与白纹伊蚊比较结果，初羽化雌蚊和吸血后５ｄ蚊血淋巴均为１３种元素，有非常显著性差异。结果提示，蚊虫血淋巴元素组成与其营养代谢、生长发育有密切关系，不同蚊种以及对疟原虫敏感性不同者也表现差异。     

Amino acid profiles in early diabetic and non-diabetic pregnancy

Plasma amino acid concentrations were measured in six insulin-dependent diabetic women and seven non-diabetic women in early pregnancy while fasting and one hour after a standard meal. Fasting plasma levels of total amino acids and individual amino acids were similar in the two groups, excepting isoleucine, which was raised in the diabetics. One hour post-prandially total amino acid concentrations were similar in the two groups; however, mean concentrations of total branched chain amino acids and mean concentration of the individual amino acids, serine, valine, isoleucine, leucine and tyrosine were elevated in the diabetics. Amino acids are important in early islet development and in insulin secretion from fetal pancreas in vitro. The elevated post-prandial amino acid levels found in pregnant diabetics in early pregnancy may contribute to fetal islet hypertrophy and hyperinsulinaemia.     

Ileal losses of nitrogen and amino acids in humans and their importance to the assessment of amino acid requirements

BACKGROUND & AIMS: Irreversible amino acid losses at the human ileum are not taken into account when tracer-derived amino acid requirements are calculated because the data available are scarce. We have investigated amino acid losses at the ileal level in humans after ingestion of a protein meal. METHODS: Thirteen volunteers ingested a single meal of 15N milk or soy proteins. The appearance of 15N and 15N amino acids in the ileal effluents collected using an ileal tube was monitored for 8 hours. RESULTS: In the soy group, higher losses of endogenous nitrogen, especially originating from amino acids, were observed, as well as a higher flow rate of dietary non-amino acid nitrogen. With soy protein, the digestibilities of valine, threonine, histidine, tyrosine, alanine, and proline were significantly lower than with milk. Ileal losses of leucine, valine, and isoleucine amounted to 12, 10, and 7 mg x kg(-1) x day(-1), respectively. Threonine ileal loss (9-12 mg x kg(-1) x day(-1)) was particularly high compared with the current amino acid requirement. CONCLUSIONS: Amino acid losses at the human terminal ileum are substantial and depend on the type of dietary protein ingested. Although it remains unclear whether intact amino acids are absorbed in the colon, we suggest that ileal losses should be considered an important component of amino acid requirements.     

荷肝癌小鼠血浆和肿瘤组织游离氨基酸代谢变化及其与肿瘤体积相关性研究

目的探讨荷肝癌小鼠游离氨基酸代谢变化,为肝癌患者氨基酸失衡疗法提供理论依据。方法采用HITACHIL8800型氨基酸分析仪,检测10例荷肝癌小鼠血浆和肿瘤组织游离氨基酸,并以10例正常小鼠做为对照组,研究氨基酸代谢变化与肿瘤体积的关系。结果荷瘤组血浆游离精氨酸、缬氨酸、丝氨酸、谷氨酸明显降低;肿瘤组织游离蛋氨酸、精氨酸、缬氨酸、亮氨酸与对应血浆游离氨基酸呈负相关;肿瘤组织游离异亮氨酸、缬氨酸、蛋氨酸、酪氨酸、亮氨酸、谷氨酸、丝氨酸与肿瘤体积呈正相关。结论肝癌在其生长过程中与某些特定氨基酸关系密切,这将为针对肝癌的氨基酸失衡处理提供实验和理论依据。     

Plasma amino acids in rheumatoid arthritis

Plasma amino acid concentrations have been investigated in 12 female patients with rheumatoid arthritis (RA), who were hospitalized for two 14-day periods, one of which included 7 days of total fasting, whereas the other served as control period with normal food intake. All medical treatment was stopped on admission to the hospital. Plasma amino acid levels were repeatedly determined during both periods. Another group, consisting of 8 healthy volunteers, also underwent total fasting, for 6 days. The response to food deprivation with regard to plasma amino acid levels was compared with that in the RA patients. The results obtained from the control period were compared with those derived from age and sex matched healthy controls. RA disease was not characterized by a typical amino acid pattern. Major increases were seen in the concentrations of taurine, aspartate, glutamate, glycine, 1-methyl histidine, isoleucine and arginine. Rather smaller yet significant elevations could be observed in the levels of cystein, threonine, serine, citrulline, methionine and leucine. The only amino acid to show a lowered concentration was alpha-aminobutyrate. Most of the alterations induced by fasting were similar to those in healthy volunteers. An exception was the levels of taurine, which evidenced in RA patients a further increase during starvation, not observed in healthy volunteers, and valine which exhibited, a smaller increment than that apparent in healthy controls. The increase in sulphur-containing amino acids might be interpreted as a sign of an enhanced glutathione (GSH) catabolism, whereas the differing metabolic behaviour of branched chain amino acids (BCAA) suggests a specific reaction of valine in RA disease, similar to that in other catabolic diseases.     

Factors affecting plasma amino acid concentrations in control subjects

Plasma amino acid concentrations were determined in groups of normal control subjects under fasting and postprandial conditions. Differences were observed that were found to be, to a considerable extent, sex-related. Fasting females had lower concentrations than fasting males of several amino acids, although postprandial differences in concentrations between the sexes were not significant. Under the dietary conditions normal for a British population, no significant diurnal variation of plasma amino acid concentrations was found. Reducing the dietary protein by 30% failed to affect plasma amino acid concentrations; however, increasing the dietary protein by 50% resulted in a significant increase in the plasma concentrations of several amino acids, and induced a significant degree of variation throughout the day in six, proline, half-cystine, methionine, valine, leucine, and isoleucine. The importance of these results with regard to the interpretation of population mean values and disease diagnosis is discussed.     

Effect of rotavirus infection on small gut pathophysiology in a mouse model

AIM: To study the effect of rotavirus infection on amino acid uptake in the small intestine in an experimental mouse model. METHODS: Infant mice (7-8 days of age) were orally infected with the EB serotype 3 strain of rotavirus and animals (both infected and control) were killed on days 0, 1, 3, 5, 7 and 10 post inoculation (PI) after recording their bodyweights. Gamma-glutamyltranspeptidase (GGT), leucine amino peptidase (LAP), glutathione (GSH) and leucine amino acid uptake in the jejunum and ileum were assessed. RESULTS: Infected animals showed significant reduction in their bodyweights and intestinal lengths on the third day PI compared with controls. Leucine amino peptidase, GGT, GSH and leucine uptake were significantly reduced in the ileum on the third and fifth day PI compared with controls while uptake in the jejunum was only reduced on third day PI. The LAP, GGTP, GSH and leucine uptake attained normal levels on the seventh day when diarrhoea stopped. Histology showed damage to the villi in the jejunum and prominent cytoplasmic vacuolation in the ileum of infected animals on the third and fifth day PI. CONCLUSION: Rotavirus affects amino acid uptake in the small intestine at the time of peak infection.     

Prophylactic trials for stroke in stroke-prone SHR. (3) Amino acid analysis of various diets and their prophylactic effect

This study confirmed again that high protein diet feeding decreased the incidence of stroke, and high fish protein diet did attenuate severe hypertension but high soybean protein diet did not affect the hypertension. Dietary amino acid analyses indicated that increases in total amino acids, essential amino acids and nonpolar amino acids but not acid or basic amino acids were significantly related to the reduction of stroke incidence. Among essential amino acids, lysine, threonine, isoleucine, and leucine contents were inversely related to stroke incidence, and methionine content was significantly related to the dietary antihypertensive effect of high protein diets. The prophylactic effect of high protein diets may be ascribed to some amino acid constituent.     

Protein tolerance to standard and high protein meals in patients with liver cirrhosis

AIM To investigate the plasma amino acid response and tolerance to normal or high protein meals in patients with cirrhosis.METHODS The plasma amino acid response to a 20 g mixed protein meal was compared in 8 biopsy-proven compensated cirrhotic patients and 6 healthy subjects.In addition the response to a high protein meal(1 g/kg body weight) was studied in 6 decompensated biopsy-proven cirrhotics in order to evaluate their protein tolerance and the likelihood of developing hepatic encephalopathy(HE) following a porto-caval shunt procedure.To test for covert HE,the "number connection test"(NCT) was done on all patients,and an electroencephalogram was recorded in patients considered to be at Child-Pugh C stage.RESULTS The changes in plasma amino acids after a 20 g protein meal were similar in healthy subjects and in cirrhotics except for a significantly greater increase(P 0.05) in isoleucine,leucine and tyrosine concentrations in the cirrhotics.The baseline branched chain amino acids/aromatic amino acids(BCAA/AAA) ratio was higher in the healthy persons and remained stable-but it decreased significantly after the meal in the cirrhotic group.After the high protein meal there was a marked increase in the levels of most amino acids,but only small changes occurred in the levels of taurine,citrulline,cysteine andhistidine.The BCAA/AAA ratio was significantly higher 180 and 240 min after the meal.Slightly elevated basal plasma ammonia levels showed no particular pattern.Overt HE was not observed in any patients.CONCLUSION Patients with stable liver disease tolerate natural mixed meals with a standard protein content.The response to a high protein meal in decompensated cirrhotics suggests accumulation of some amino acids but it did not precipitate HE.These results support current nutritional guidelines that recommend a protein intake of 1.2-1.5 g/kg body weight/day for patients with cirrhosis.     

斯氏按蚊血淋巴酚氧化酶与约氏疟原虫卵囊黑化的关系

[目的 ]探讨酚氧化酶 (phenoloxidase,PO)与疟原虫卵囊黑化的关系。 [方法 ]以斯氏按蚊 /约氏疟原虫为模型 ,对 4组斯氏按蚊 (不吸血组、吸正常血组、吸感染血组和硝喹组 )血淋巴进行聚丙烯酰胺凝胶电泳 (PAGE)和凝胶图像分析 ,检测单酚氧化酶 (monophenoloxidase ,MPO)和二酚氧化酶 (diphenoloxidase,DPO)活性。 [结果 ]吸正常血组和不吸血组蚊血淋巴中MPO及o DPO活性无明显差异 ;与吸正常血组或不吸血组相比 ,感染组MPO及o DPO活性无明显变化 ,但用药组d1 0 则显著增加 ,d1 5 显著降低。 [结论 ]斯氏按蚊血淋巴中PO活性变化与约氏疟原虫卵囊黑化在时间上一致。     

Evaluation of circulating levels and renal clearance of natural amino acids in patients with Cushing's disease

Although the hypercortisolism-induced impairment of protein homeostasis is object of several studies, a detailed evaluation of the complete amino acid profile of patients with Cushing's syndrome (CS) has never been performed. The aim of the current open transversal controlled study was to evaluate serum and urinary concentrations as well as renal clearance of the complete series of natural amino acids and their relationship with glucose tolerance in patients with Cushing's disease (CD). Twenty patients with CD (10 active and 10 cured) and 20 sex- and age-matched healthy controls entered the study. Measurement of serum and urinary levels of the complete series of natural amino acids was performed in all patients analyzed by cationic exchange high performance liquid cromatography (HPLC) after 2 weeks of a standardized protein intake regimen. The renal clearance (renal excretion rate) of each amino acid was calculated on the basis of the serum and urinary concentrations of creatinine and the specific amino acid. Fasting glucose and insulin levels, glucose and insulin response to standard glucose load, insulinogenic and homeostasis model insulin resistance (Homa-R) indexes were also evaluated and correlated to the circulating levels and renal clearances of each amino acid. Significantly higher serum (p<0.01) and urinary (p<0.05) levels of alanine and cystine, lower serum and higher urinary levels of leucine, isoleucine and valine (p<0.05) and higher renal excretion rates of leucine, isoleucine and valine (p<0.01) were found in patients with active CD than in patients cured from the disease and in controls. No difference was found between cured patients and controls. Creatinine clearance was similar in active and cured patients and in controls. In patients with active CD, urinary cortisol levels were significantly correlated to urinary cystine levels (r=0.85; p<0.01) and renal excretion rate of leucine (r=-0.76; p<0.05), isoleucine (r=-0.76; p<0.05) and valine (r=-0.66; p<0.05). Fasting blood glucose levels were significantly correlated to serum alanine levels (r=0.70; p<0.05). Although Homa-R was significantly correlated to BMI in active patients (r=0.74 p<0.05), it was not correlated to amino acid levels. In conclusion, the results of the current study demonstrate that patients with CD have significant changes in serum and urinary concentration of several amino acids and changes in renal clearance of some specific amino acids. Normalization of cortisol levels restored the amino acid profile.     

Changes in plasma amino acids during the oral glucose tolerance test in hepatic diseases

We have measured the plasma concentration of neutral amino acids before and after an oral glucose tolerance test (100 g) in patients with liver cirrhosis (LC), chronic active hepatitis (CAH), chronic persistent hepatitis (CPH), acute hepatitis in the acute stage (AHa) and acute hepatitis in the convalescent stage (AHc) and normal controls. The ratio of the concentration of an amino acid to the sum of those of the other neutral amino acids that compete during transport through the blood brain barrier (BBB), which was reported to correlate well with the brain level of the amino acid, was compared in patients with various liver diseases. The ratios of Trp (Trp/Tyr + Phe + Ile + Leu + Val), Tyr, Phe, and Val increased after glucose loading in all subjects, except Tyr in normal controls, which slightly decreased. On the other hand, Ile and Leu ratios decreased (Trp; tryptophan, Tyr; tyrosine, Phe; phenylalanine, Ile; isoleucine, Leu; leucine, Val; valine). LC showed a characteristic pattern; the ratios of Trp and Tyr were highest among all diseases at 3 hours after glucose loading, and those of Ile, Leu and Val were lowest. We assumed that delta an amino acid ratio = the amino acid ratio at 3 hrs after glucose loading minus the amino acid ratio at 0 hr. In LC, delta Trp ratio and delta Tyr ratio were highest, while delta Val ratio was lowest. The delta Phe ratios in AHa and AHc were significantly higher than those in healthy controls. From these results, the uptake of Trp and Tyr might be supposed to be highest and that of Val was lowest in LC, after glucose loading.