Adenosine and adenine nucleotides are independently released from both the nerve terminals and the muscle fibres upon electrical stimulation of the innervated skeletal muscle of the frog

The independent release of adenosine and adenine nucleotides upon electrical stimulation was studied in the innervated sartorius muscle of the frog after blockade of the extracellular catabolism of adenosine monophosphate (AMP) through exo-AMP deaminase and ecto-5-nucleotidase. Nerve stimulation (30 min, 0.2Hz) induced the release of both adenosine (19±3 pmol) and adenine nucleotides (101±7 pmol). Experiments performed in the presence of tubocurarine (5 M) to prevent purine release due to nerve-evoked muscle twitching, or under direct stimulation of the muscle in low calcium solutions to prevent pre-synaptic release of purines, showed that there was an evoked release of adenosine and adenine nucleotides both from the nerve endings and from the twitching muscle fibres. Removal of ecto-5-nucleotidase inhibition shows that the catabolism of adenine nucleotides released during stimulation contributes in about 50% to the amount of endogenous extracellular adenosine. When only one of the enzymes catabolizing AMP (ecto-5-nucleotidase or exo-AMP deaminase) was inhibited, the evoked release of adenine nucleotides was undetectable, suggesting that each enzyme is able to catabolize all the AMP formed from adenine nucleotides released upon stimulation. It is concluded that the concentration of endogenous extracellular adenosine is under the control of the relative activities of exo-AMP deaminase and ecto-5-nucleotidase.Brief accounts of some of the results in this study have been published previously (refs. [6, 7]).     

<Emphasis Type="Italic">Trichomonas vaginalis</Emphasis>: cytochemical localization of a NTPDase1 and an ecto-5′-nucleotidase and effects of adenine nucleotides on cellular viability

Nucleoside triphosphate diphosphohydrolase 1 (NTPDase1), which hydrolyzes extracellular ATP and ADP, and ecto-5-nucleotidase, which hydrolyzes AMP, are characterized for Trichomonas vaginalis. Ultrastructural cytochemical microscopy showed NTPDase1 and ecto-5-nucleotidase activities on the surface of the parasites. High levels of extracellular adenine nucleotides and adenosine did not exert cytolytic effects in intact cells of T. vaginalis. Our results suggest that these enzymes are relevant for the survival of the parasite during exposure to extracellular nucleotides. Since the ecto-localization of these enzymes is essential for the maintenance of adenosine extracellular levels, this nucleoside could be important for the purine salvage pathway in the parasite.     

5′-Nucleotidase activity as a synaptic marker of parasagittal compartmentation in the mouse cerebellum

Summary In the molecular layer of the mouse cerebellum, the histochemical activity of the adenosine-producing ectoenzyme 5-nucleotidase discloses a parasagittal pattern of alternating enzyme-rich and enzyme-poor bands. In the rat, 5-nucleotidase activity transiently labels cerebellar synapses during postnatal development and shifts later on towards an exclusive glial location in the molecular layer. We therefore asked whether different ultrastructural expression of 5-nucleotidase would account for the light microscopic pattern seen in the adult mouse cerebellum. Using an enzyme cytochemical method, we localized 5-nucleotidase activity on the glial cells and at the main types of asymmetrical synapses in the developing and mature cerebellum of the mouse. The percentage of labelled synapses increased until adulthood within the 5-nucleotidasepositive bands. Here, the vast majority (86%) of the synapses were labelled against only 27% within the negative bands in the adult. Thus, 5-nucleotidase appears as a marker of glia and of Purkinje cell synapses across cerebellar compartments. Changes in purinergic neuromodulation and/or cell adhesion mediated by 5-nucleotidase across bands might participate in the functional differentiation of the cerebellar parasagittal subsets.     

Production of AMP and adenosine in the interstitial fluid compartment of the isolated perfused normoxic guinea pig heart

The pathway of production of AMP and adenosine in the myocardial interstitial fluid compartment was studied in the isolated perfused normoxic guinea pig heart by collecting the transmyocardial effluent (t.m.e.) with the method of De Deckere and Ten Hoor (1977). Besides adenosine and inosine, AMP was found in t.m.e. Infusion of ,-methylene adenosine 5-diphosphate (AOPCP), a specific inhibitor of the ecto 5-nucleotidase, resulted in increases in t.m.e. AMP and inosine and a decrease in adenosine. Infusion of acetate producing a nearly twofold increase in myocardial AMP content did not increase the t.m.e. AMP even in the presence of AOPCP. In preparations made from 6-OH dopamine treated animals, the t.m.e. adenosine and inosine were reduced and AOPCP produced smaller increases in AMP and inosine, indicating that most if not all of the t.m.e. AMP originated from the sympathetic nerve terminals. Infusions of ,-imidoadenosine and ,-methylene adenosine 5-triphosphate (AMPPNP and AMPPCP), non-hydrolysable analogs of ATP, resulted in dose-dependent increases in the t.m.e. AMP, which were much augmented in the presence of AOPCP. AMPPNP produced similar effects in 6-OH dopamine-treated preparations. As AMPPNP and AMPPCP are good substrates of ATP pyrophosphohydrolase, these findings indicate the presence of ATP pyrophosphohydrolase in the myocardial interstitial space.     

Die seltenen Rh-Phänotypen rhy rh und rh′ rh′ in einer deutschen Familie

Zusammenfassung Nach einer Literaturübersicht wird das Vorkommen der seltenen Rh-Genotypen rr und rr in 2 Generationen einer deutschen Familie beschrieben.     

Enzymes of purine metabolism in lymphoid neoplasms,clinical relevance for treatment with enzyme inhibitors

Summary A few enzymes of the purine degradative pathway have proved valuable in diagnosis and treatment of lymphomas and lymphocytic leukemia. Of particular interest are the enzymes adenosine deaminase (ADA), purine nucleoside phosphorylase (PNP) and ecto-5-nucleotidase (5NT). Intact activities of ADA and PNP have been shown to be vital for lymphoid cells. During development, lymphoid precursors go through remarkable changes in the concentrations of these enzymes and the neoplasma derived from them show a frozen biochemical profile similar to the corresponding normal cell of origin. Knowledge of the role of these enzymes has led to the pharmacological use of enzyme inhibitors for the specific treatment of lymphoid neoplasms. This review concerns the enzymatic make-up of normal and neoplastic lymphocytes and exploitation of this knowledge for the treatment of lymphomas. Special emphasis will be put on the clinical use of an ADA-inhibitor, deoxycoformycin.Abbreviations ADA Adenosine deaminase - ALL Acutelymphocytic leukemia - CdA 2-Chloradeoxyadenosine - CLL Chronic lymphocytic leukemia - dATP Deoxyadenosine triphosphate - dCTP Deoxycytidine triphosphate - dGTP Deoxyguanosine triphosphate - 5NT Ecto-5-nucleotidase - PNP Purine nucleoside phosphorylase - SAH S-adenosylhomocysteine - SAM S-adenosyl-methionine - SCID Severe combined immunodeficiency disease Dedicated to Professor Werner Hunstein on the occasion of his 60th birthday     

Adenosine 3′,5′-cyclic monophosphate in rabbit cerebrospinal fluid during fever induced byE. coli-endotoxin

In rabbit cerebrospinal fluid during fever induced byE. coli-endotoxin adenosine 3,5-cyclic monophosphate concentrations are about 2-fold higher in comparison to normal values. In addition to prostaglandins of the E series adenosine 3,5-cyclic monophosphate might act as another mediator in the genesis of fever during infectious diseases.This investigation was supported by the Deutsche Forschungsgemeinschaft.     

Effects of 5-hydroxytryptamine,dopamine, and acetylcholine on accumulation of cyclic AMP and cyclic GMP in the anterior byssus retractor muscle ofMytilus edulis L. (Mollusca)

We investigated in vitro accumulation of adenosine 3,5-monophosphate (induced by 5-hydroxytryptamine and dopamine) and of guanosine 3,5-monophosphate (induced by acetylcholine) in the anterior byssus retractor muscle ofMytilus.The response to 5-hydroxytryptamine exceeded that induced by equimolar concentrations of dopamine.1-methyl lysergic acid, a 5-hydroxytryptamine-blocking agent, diminished the 5-hydroxytryptamine-induced increase of cyclic AMP level. This parallels the effect of this amine on the contracted muscle.Acetylcholine, which causes a tonic contraction of the muscle, increased intracellular levels of cyclic GMP in a dose-dependent (max. 45-fold at 10^–4 M ACh) manner. The time course of the rise in cyclic GMP level was rapid and transient (peak concentration of cyclic GMP at 2 min).Mytolon was the most effective of all cholinergic blockers tested. It was concluded that cyclic nucleotides may play a role in the modulatory process of the transmitters. A direct relation to the relaxation-contraction process could not be established.Abbreviations ABRM anterior byssus retractor muscle - cyclic AMP adenosine 3,5-monophosphate - cyclic GMP guanosine 3,5-monophosphate - ACh acetylcholine - 5-HT 5-hydroxytryptamine, serotonin - DA dopamine - TCA trichloroacetic acid - UML 1-methyl lysergic acid hydrogen maleinate     

Attenuated Lapinized Chinese Strain of Classical Swine Fever Virus: Complete Nucleotide Sequence and Character of 3′-Noncoding Region

The complete nucleotide sequence including precise 5- and 3-terminal non-coding regions (NCRs) of the attenuated lapinized Chinese strain (HCLV) of Classical Swine Fever Virus (CSFV) was determined from overlapping cDNA clones constructed by separated RT-PCR and rapid amplification of cDNA ends (RACE) methods. The genomic RNA of the HCLV strain consists of 12,310 nucleotides (nts) including 374nts and 242nts in the 5- and 3-NCRs, respectively. It contains one large open reading frame (ORF) encoding a polyprotein of 3,898 amino acids with a calculated molecular weight of 437.6kDa. There is one notable insertion of 12 continuous nts, CTTTTTTCTTTT in the 3-NCR of HCLV genomic cDNA when compared with its parental virulent Shimen strain. Sequence alignment of partial 3-NCR reveals two groups of CSFV vaccine strains carrying similar T-rich insertions at different positions in this region. Computer-predicted secondary structures suggest that T-rich insertion greatly change the structures and thus decrease the promoter functions of 3-NCRs during the replications of these two groups of CSFV vaccine strains.     

Komplement- und Antikörper-Titer bei Patienten mit chronischer Bronchitis

Zusammenfassung Bei insgesamt 76 Patienten mit chronischer Bronchitis wurden Komplement(C)- und Antikörper(Ak)Titer (gegen die jeweiligen aus Sputumproben gezüchteten Keime) bestimmt. Die C-Titer (CH50/ml) lagen bei 57 Patienten (= 75%) im Normbereich, bei 17 Patienten (= 22,4%) oberhalb und bei 2 Patienten (= 2,6%) unterhalb der Grenzwerte bei Kontrollpersonen. Dabei tendierten bei höheren Ak-Titern die C-Titer zu niedrigeren Werten. Es wird vermutet, daß kontinuierliche Immunreaktionen den relativen Abfall der C-Titer bei gleichzeitig hohen Ak-Titern bedingen.

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Summary In 76 patients with chronic bronchitis total complement (C) activity and antibody titer (versus correspondent microorganisms cultured from sputum samples) were determined. 57 patients (= 75%) were found to have normal C titers (CH50/ml), in 17 cases (= 22,4%) the C titers were elevated above and in 2 cases (= 2,6%) reduced under limiting values of control persons. The C titers tended to lower levels when antibody titers increased. It is supposed that continuous immune reactions cause the relative decrease of complement activity when antibody titers are increased.

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Mit finanzieller Beihilfe der Europäischen Gemeinschaft für Kohle und Stahl durchgeführte Forschungsarbeit.