铜－嘌呤配位吸附波研究

本文提出了Ｃｕ（Ⅱ）──嘌呤配位吸附波。在ｐＨ为６．９０的Ｂ·Ｒ缓冲溶液中，该波的峰电位为－０．２４０（Ｖ）（ｖｓ·ＳＣＥ），对极谱波的电流，电位性质和电极反应机理进行了研究，利用该波的一阶导数值可测定铜离子浓度，检测下限为９．０×１０￣（－８）ｍｏｌ·ｄｍ￣（－３）。     

Effect of synthetic purines and purine nucleosides on [3H]diazepam binding in brain

We have compared fifteen synthetic purines and purine nucleosides on their ability to displace [³H]diazepam binding to rat brain membranes. Among these analogs, 6-methylthioguanine was found to be most potent, inhibiting competitively the specific binding of [³H]diazepam with a K_i value of 16 μM. At a concentration of 50 μM, 6-methyl-thioguanine increased the apparent K_D of specific diazepam binding from 4.3 nM to 13.3 nM without affecting the B_max, nor had it any effect on the non-specific binding. Binding with membrane preparations from developing rat brain was slightly less sensitive to 6-methylthioguanine inhibition than that with membranes prepared from mature brain.     

Influence of peripheral arterial occlusive disease on muscular metabolism

Summary The concentrations of lactate, ammonia and hypoxanthine were determined in blood from the femoral artery, femoral vein and cubital vein under resting conditions in 23 patients with stage II, 10 patients and 20 diabetics with stage IV peripheral arterial occlusive disease (PAOD) and in 19 healthy subjects. The metabolite concentrations were also measured immediately and 20 min after calf exercise in the patients with stage II PAOD and in the controls. At rest, there was a negative arteriovenous difference in femoral lactate level and a positive arteriovenous difference in the ammonia level in all groups. After exercise to the claudication limit, the femoral venous concentration and arteriovenous difference for lactate increased in the patient group significantly higher than in the controls, who were exercised three times as heavily. Furthermore, there was a significant rise in femoral venous ammonia concentration with inversion of the arteriovenous difference into the negative range and an increase in femoral venous hypoxanthine concentration only in the patients with PAOD and not in the controls. A significant correlation was found between the exercise-induced increases in lactate and ammonia. The results indicate activation of the purine nucleotide cycle in the muscles of limbs with impaired circulation, even for a short duration of load. This can be explained by activation of the AMP-deaminase in type I and type IIa muscle fibres by anoxaemia. The purine nucleotide cycle has an emergency metabolic function in ischaemia to maintain muscle contractility. Ammonia determination in femoral blood permits, in association with lactate and hypoxanthine determination, a precise quantitative assessment of the metabolic effects of PAOD.Abbreviations ADP adenosine diphosphate - AMP adenosine monophosphate - ATP adenosine triphosphate - AVD arteriovenous difference - IMP inosine monophosphate - PAOD peripheral arterial occlusive disease - PNC purine nucleotide cycle Dedicated to Prof. Dr. R. Hild on the occasion of his 60th birthday     

Adenosine deaminase and purine nucleoside phosphorylase levels in acute myeloblastic leukemia cells. Relationship to diagnosis and clinical course.

The two enzymes adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP), which are essential for normal lymphocyte function, have been investigated in leukemia.The enzyme activities have been measured in leukemia cells from 20 patients with AML, 19 patients with other leukemias and in leukocytes from 63 normal persons. It was found that the ADA activity in AML cells was above the normal range (P<0.01), with a correlation between peripheral blast percentage and ADA level (P<0.02). There was a slight relationship between the clinical course and survival time, response to chemotherapy (P<0.1) and survival time (P > 0.1), and ADA activity. Variable but also abnormal activities were found in other leukemias. The significance of increased ADA levels is discussed.The levels of PNP, which has not been determined before in AML in relation to ADA, showed remarkably constant levels. The levels in AML and the other groups analysed were essentially the same as those found in normal leukocytes.     

Credentials of Spirulina diet on stability and flux related properties on the biomineralization process during oxalate mediated renal calcification in rats

BACKGROUND: High Spirulina diet is a potential risk factor for nephrolithiasis since it has the capacity to increase urinary oxalate and uric acid level, facilitating lithogenesis. Our aim was to identify the effect of Spirulina diet during hyperoxaluric condition in Wistar albino rats. METHODS: The animals were divided into four groups: control (Gl, n=6); ethylene glycol (EG) induced (G2, n=6); EG+Spirulina (G3, n=6); Spirulina alone (G4, n=6). EG at 0.75% was administered to G2 and G3 through drinking water for 4 weeks and Spirulina 1500 mg/kg feed was administered to G3 and G4. RESULTS: Urinary parameters like oxalate, uric acid, calcium, urea, and creatinine (P<0.001) were found increased after Spirulina diet under hyperoxaluric conditions compared to the same without Spirulina diet. Similarly the BUN, plasma contents of uric acid, urea, creatinine (P<0.001) were found to be raised in G3. The renal and RBC GSH levels, as estimated by HPLC, seemed decreased when compared to G2. CONCLUSIONS: The present study shows that free radicals aid in the progression of nephrolithiasis. The crystal deposition was found to be high in the renal cells of G3 than G2 and TEM revealed damage in renal cell of G3 implying that the disease deteriorates by free radical injury. In contrast the Spirulina diet alone (G4) did not induce any features relating to stone forming condition suggesting that free radical release might have been suppressed due to enrichment of dietary antioxidants and vitamins. Thus the present investigation demonstrates that during hyperoxaluric conditions the Spirulina diet must possibly be avoided and can be considered in normal subjects checked for family history of renal stone deposition.     

Purine nucleoside phosphorylase deficiency (PNP-def) presenting with lymphopenia and developmental delay: successful correction with umbilical cord blood transplantation

Purine nucleoside phosphorylase deficiency is a primary immunodeficiency syndrome characterized by the triad of recurrent infection, neurologic dysfunction, and autoimmunity. This patient presented atypically with few infections and normal T-cell function. Progressive lymphopenia, ataxia, and developmental delay led to diagnosis. Umbilical cord blood transplantation corrected the immunodeficiency.     

Differences between rat primary cortical neurons and astrocytes in purine release evoked by ischemic conditions

In the brain, the levels of adenosine increase up to 100-fold during cerebral ischernia; however, the roles of specific cell types, enzymatic pathways and membrane transport processes in regulating intra- and extracellular concentrations of adenosine are poorly characterized. Rat primary cortical neurons and astrocytes were incubated with [(3)H]adenine for 30 min to radiolabel intracellular ATP. Cells were then treated with buffer, glucose deprivation (GD), oxygen-glucose deprivation (OGD), 100 micro M sodium cyanide (NaCN) or 500 micro M iodoacetate (IAA) for 1 h to stimulate the metabolism of ATP and cellular release of [(3)H]purines. The nucleoside transport inhibitor dipyridamole (DPR) (10 micro M), the adenosine kinase inhibitor iodotubercidin (ITU) (1 micro M), the adenosine deaminase inhibitor EHNA (1 micro M) and the purine nucleoside phosphorylase inhibitor BCX-34 (10 micro M) were tested to investigate the contribution of specific enzymes and transporters in the metabolism and release of purines from each cell type. Our results indicate that (a). under basal conditions astrocytes released significantly more [(3)H]adenine nucleotides and [(3)H]adenosine than neurons, (b). OGD, NaCN and IAA conditions produced significant increases in [(3)H]adenosine release from neurons but not astrocytes, and (c) DPR blocked [(3)H]inosine release from both astrocytes and neurons but only blocked [(3)H]adenosine release from neurons. These data suggest that, in these experimental conditions, adenosine was formed by an intracellular pathway in neurons and then released via a nucleoside transporter. In contrast, adenine nucleotide release and extracellular metabolism to adenosine appeared to predominate in astrocytes.     

Pharmacokinetics,anticonvulsant efficacy,and adverse effects of trans-2-en-valproate after acute and chronic administration in amygdala-kindled rats

Summary Effects of adenosine and nucleotides on the release of previously stored [3H]-noradrenaline were studied in rabbit brain cortex slices. The slices were stimulated twice, in most experiments by 6 electrical field pulses delivered at 100 Hz.Adenosine and the nucleotides AMP, ADP, ATP, AMPS, ADPS, ATPyS, ,-imido-ATP and ,-methyl-ene-ATP all reduced the evoked overflow of tritiated compounds. For purines for which concentration-response curves were determined, the order of potency was adenosine > ATP ATPyS ,-imido-ATP ADP > ,-methylene-ATP. AMP 30 Etmol/l and AMPS 30 mol/l were approximately equieffective with 30 mol/l of adenosine and ATPS, and ADPS, 30 mol/l was approximately equieffective with 30 mol/l of ADP. ,-Methylene-ADP, 2-methylthio-ATP, UTP and GTPS did not change the evoked overflow of tritium. ,-Methylene-ATP caused an increase; however, the increase was small and became significant only after 59 min of exposure to ,-methylene-ATP or when the slices were stimulated by 30 pulses, 10 H₂. Neither adenosine deaminase (100 U/l) nor the blocker of 5-nucleotidase, ,-methylene-ADP (10 mol/l), attenuated the inhibition caused by ATP, ATPyS and ,-methylene-ATP, despite the fact that adenosine deaminase abolished the effect of adenosine. 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX, 10 nmol/l) shifted the concentration-response curves of adenosine, ATPyS, ,-imido-ATP and ,-methylene-ATP to the right by very similar degrees. 8(p-Sulphophenyl)-theophylline (30 and 300 mol/l) also markedly antagonized the inhibition produced by ATPS. ,-Methylene-ATP (10 and 30 mol/l) and suramin (100 gmol/l) did not modify the effects of adenosine, ATPS and ,-methylene-ATP.It is concluded that nucleotides themselves can inhibit the release of noradrenaline in the rabbit brain cortex. The nucleotides and adenosine seem to act at the same site, i.e., the A₁ subtype of the P₁-purinoceptor. The results support the notion that metabolically stable, phosphate chain-modified nucleotides such as ATPS, ,-imido-ATP and ,-methylene-ATP can be potent P₁ agonists. No evidence was found for presynaptic P_2X-, P_2Y- or P₃-purinoceptors. Send offprint requests to I. von Kugelgen at the above address     

Prenatal exclusion of purine nucleoside phosphorylase deficiency

We report on the prenatal exclusion of purine nuclcoside phosphorylase (PNP) deficiency in a fetus whose parents were known to be heterozygotes for the enzyme defect. Prenatal investigation was performed in the 16th week of gestation on amniotic fluid and cultured amnion cells using sensitive techniques. The results suggested that the fetus was either normal or a heterozygote. PNP activity in cord red cells confirmed the heterozygous status of the baby.Abbreviations ADA adenosine deaminase - HPLC high pressure liquid chromatography - PNP purine nucleoside phosphorylase - RBCs red blood cells     

Pharmacological characterization of B-HT 933 (2-amino-6-ethyl-4,5,7,8-tetrahydro-6H-oxazolo-[5,4-d]-azepindihydrochloride) as a hypotensive agent of the “Clonidine-type”

Summary The contractile responses to transmural stimulation of, and the overflow of tritium from the rat portal vein prelabelled with ³H-noradrenaline were studied.The contractile responses of the rat portal vein were sustained throughout the period of stimulation. The tension developed did not decline when two consecutive periods of stimulation were compared. In contrast, the tritium overflow decreased during the second period of stimulation.Preincubation with 3 M phenoxybenzamine during 30 min increased 3-fold the tritium overflow during stimulation.Phentolamine and phenoxybenzamine were nearly equipotent in reducing the vascular response to stimulation. In contrast, phentolamine was less potent than phenoxybenzamine in increasing the ³H-noradrenaline overflow elicited by stimulation.The results obtained with phentolamine are interpreted in terms of a different potency of phentolamine to produce blockade of prejunctional and postjunctional -adrenoceptors in the rat portal vein.ATP inhibited by 70% the tritium overflow induced by stimulation. The potency of ATP in inhibiting the overflow increased when the prejunctional -adrenoceptors were blocked.The purine compounds ATP, ADP, AMP and adenosine were roughly equipotent in inhibiting stimulation-induced tritium overflow. The tritium released by stimulation decreased when uptake and metabolism of adenosine were inhibited. Under physiological conditions, a prejunctional purinergic inhibition of noradrenaline release might be involved in an endogenously mediated negative feed-back regulatory mechanism. It is possible that the purinergic inhibition of the noradrenaline liberation elicited by stimulation plays a physiological role in tissues with both purinergic and adrenergic innervation.