L-精氨酸脂质体对慢性低O2高CO2肺血管L-精氨酸转运的影响

目的:探讨慢性低O₂高CO₂对大鼠肺动脉L-精氨酸(L-Arg)转运的影响与L-Arg脂质体的作用。方法:雄性SD大鼠40只,随机分成4组,正常对照组(NC)、单纯低O₂高CO₂组(HH)、低O₂高CO2加L-Arg组(HL)和低O₂高CO₂加L-Arg脂质体组(HP)。将肺动脉孵育,测定其对[³H]-L-Arg的摄取率,同时光镜下观察肺细小动脉显微结构的变化。结果:(1)肺动脉平均压(mPAP)、右心室(RV)和左心室加室间隔(LV+S)重量比值(RV/LV+S)比较:HH组明显高于NC组(P<0.05),HP组明显低于HH组及HL组(P<0.01);HL组与HH组相比无显著差别(P>0.05)。(2)肺动脉薄片对0.005mmol/L、0.01mmol/L、0.02mmol/L、0.05mmol/L、0.1mmol/L和0.2mmol/L[³H]-L-Arg摄取率比较:HH组明显低于NC组,HL组明显高于HH组;HP组显著高于HH组及HL组(P<0.01)。(3)光镜下HH组肺细小动脉内弹力板扭曲,中膜平滑肌细胞增生,管腔明显狭窄;HP组肺细小动脉内弹力板扭曲明显减轻,中膜平滑肌层变薄,管壁较均匀一致。结论:慢性低O₂高CO₂大鼠肺血管存在L-Arg的转运障碍,用脂质体作为载体可显著提高肺血管对L-Arg的跨膜转运,L-Arg脂质体治疗慢性肺动脉高压具有潜在临床应用价值。     

Behavior of pancreatic glucagon,insulin, and HGH in liver cirrhosis,after arginine and i.v. glucose

Summary The authors studied the behavior of plasma levels of glucagon, HGH and insulin in a group of cirrhotic patients both in basal conditions and after i.v. arginine and glucose in order to assess their respective importance in the pathogenesis of carbohydrate disorders. After i.v. arginine an increased plasma concentration of pancreatic glucagon was found which reached its highest level at 15 min; i.e. glucose did not suppress the increased plasma glucagon levels. Plasma HGH which is consistently increased is not influenced by i.v. glucose. Plasma insulin was consistently raised during both tests; however, the insulinogenic index after i.v. glucose behaved like that of mild diabetics. The true importance of glucagon in the pathogenesis of carbohydrate intolerance in cirrhotics cannot as yet be determined with certainty; according to the authors, hyperglucagonemia is not the primary factor but only one of the main causes of this intolerance.     

原发性高血压病人红细胞L-精氨酸/一氧化氮系统的改变

目的 :探讨原发性高血压病人红细胞精氨酸 /一氧化氮系统的改变。方法 :通过核素标记测定红细胞3H L Arg转运的特征 ;一氧化氮合酶 (NOsynthase ,NOS)改良法测定红细胞NOS活性 ;放射免疫法测定环磷酸鸟苷(cGMP)的含量。结果 :高血压组红细胞L Arg摄入的最大转运速率 (Vmax)较正常组明显降低 ,但两组L Arg转运的亲合力 (Km)无差异。其中高血压组经过Y+通道的Vmax与正常对照组比较明显下降 ,Km与正常组无差别。经过Y+L通道的Vmax与正常对照组比较无变化 ,Km升高。高血压组红细胞NOS生成量及NOS活性均降低。高血压时红细胞中的cGMP的含量也较正常人明显减少。结论 :高血压时红细胞利用精氨酸生成一氧化氮的能力下降     

精氨酸对肠粘膜屏障功能的影响

目的：了解精氨酸对肠粘膜屏障功能的影响。方法：雄性ＳＤ大鼠３０只,随机分为三组。精氨酸组予精氨酸０．２５ｇ腹腔注射,假手术组和肠梗阻组予生理盐水作对照,１次／ｄ,共５ｄ。再手术将肠梗阻组、精氨酸组大鼠结扎回肠,造成单纯性机械性肠梗阻模型,假手术组仅作剖腹探查。术后２４ｈ处死大鼠采集标本。结果：①细菌移位率和移位数水平肠梗阻组和假手术组相比明显升高,精氨酸组和肠梗阻组相比明显减少。②血浆内毒素水平肠     

Recurrent hypertonic dehydration due to selective defect in the osmoregulation of thirst

A 6-year-old girl with recurrent episodes of hypertonic dehydration was studied. She denied thirst even with a plasma osmolality as high as 421 mosmol/kg. The hypernatremia was associated with an ability to concentrate urine (854 mosmol/kg). Volume expansion with water corrected hypernatremia (162 to 148 mEq/l) and resulted in an increased urine flow and urinary dilution (137 mosmol/kg) because of suppression of endogenousvasopressin (AVP) release (5.1 pg/ml). Hypertonic saline infusion raised the plasma AVP level (25.6 pg/ml) in response to changes in plasma osmolality (305 to 330 mosmol/kg) and led to a maximal urine osmolality of 818 mosmol/kg. With chronic forced fluid intake, the patient maintained a normal resum sodium concentration (range, 135–145 mEq/l) with a urine osmolality as low as 65 mosmol/kg. These findings are consistent with an isolated defect in the osmoregulation of thirst as the cause of the chronic hypertonic dehydration without deficiency in AVP secretion.     

Yeast arginine permease: nucleotide sequence of the CAN1 gene

Summary The yeast CAN1 gene, thought to encode arginine permease, has found use in genetics as a selectable locus. We have sequenced the cloned CAN1 gene, which contains an open reading frame of 1770 nucleotides, encoding a polypeptide of calculated molecular weight 65,766. Disruption of this open reading frame largely abolishes CAN1 gene expression, while subcloned fragments of the open reading frame hybridize strand —specifically to a 2.3 kb yeast RNA message. The encoded protein has no leader signal sequence, and is highly hydrophobic, with a possible twelve membrane-spanning domains, several of which have the high hydrophobic moments seen in channel-forming or permease proteins. This protein structure is consistent with the CAN1 product being the plasma membrane arginine permease.     

Oxytocin, vasopressin, and human social behavior

There is substantial evidence from animal research indicating a key role of the neuropeptides oxytocin (OT) and arginine vasopressin (AVP) in the regulation of complex social cognition and behavior. As social interaction permeates the whole of human society, and the fundamental ability to form attachment is indispensable for social relationships, studies are beginning to dissect the roles of OT and AVP in human social behavior. New experimental paradigms and technologies in human research allow a more nuanced investigation of the molecular basis of social behavior. In addition, a better understanding of the neurobiology and neurogenetics of human social cognition and behavior has important implications for the current development of novel clinical approaches for mental disorders that are associated with social deficits (e.g., autism spectrum disorder, social anxiety disorder, and borderline personality disorder). This review focuses on our recent knowledge of the behavioral, endocrine, genetic, and neural effects of OT and AVP in humans and provides a synthesis of recent advances made in the effort to implicate the oxytocinergic system in the treatment of psychopathological states.     

Effect of corticosteroids on arginine vasopressin after pediatric cardiac surgery

Introduction

Arginine vasopressin’s (AVP) efficacy in the treatment of refractory hypotension is, in part, dependent upon preinfusion endogenous AVP concentration. Corticosteroids, also commonly used to treat refractory hypotension, have been shown to suppress endogenous AVP release. We aimed to determine if corticosteroids affect endogenous AVP concentrations in children recovering from cardiac surgery.

Materials and methods

We reviewed the records of children who underwent cardiac surgery between January 2008 and January 2009 and had AVP concentrations available as part of a prior prospective study. Doses of hydrocortisone, methylprednisolone, and dexamethasone administered within the first 48 hours after cardiopulmonary bypass were quantitated. Multivariable linear regression was performed to determine if corticosteroids had a significant effect on 48-hour plasma AVP concentration.

Results

Sixty-nine children with plasma AVP concentrations available were reviewed, 34 (49%) of which received corticosteroids within 48 hours after cardiopulmonary bypass. On multivariable regression, greater number of corticosteroid doses but not cumulative corticosteroid dosage was significantly associated with low 48-hour AVP concentration (β = − 4.0; 95% confidence intervals, − 6.5 to − 1.4).

Conclusions

Children who receive multiple doses of corticosteroids after cardiac surgery, regardless of potency, are likely to have low endogenous AVP concentrations. Children who remain unstable despite corticosteroids may respond favorably to exogenous AVP therapy.     

穹窿切断并摘除肾上腺后大鼠下丘脑AVP表达变化

目的:探讨海马参与肾上腺(HPA)轴调节的机制,观察精氨酸加压素(arginine vasopressin,AVP)与糖皮质激素的关系。方法:建立大鼠穹窿切断模型,采用酶联免疫吸附试验(ELISA)方法检测穹窿切断0、4、7、10 d血中糖皮质激素的浓度;建立大鼠穹窿切断同时摘除肾上腺7 d的模型,采用免疫组织化学方法检测AVP的表达变化。结果:穹窿切断7 d后血中糖皮质激素的浓度升高,穹窿切断同时摘除肾上腺7 d后,下丘脑AVP表达升高。结论:海马通过穹窿对HPA轴发挥负反馈调节作用,糖皮质激素负反馈调节下丘脑AVP。