[Block of the slow pathway of the double atrioventricular node: a new technique for treatment of atrioventricular node reentry tachycardia]

The aim of this work is to summarize the first experience in Chile modifying the slow pathway in patients with tachycardias due to atrio-ventricular node reentry. Until now, the only available treatment was the use of antiarrhythmic drugs. The radiofrequency fulguration or cauterization of part of the atrioventricular node has been reported as a treatment for these arrhythmias. The initial technique fulgurated the rapid pathway with a significant risk of atrioventricular block. The modification of the slow pathway has been recently described. We report two patients, 9 and 45 years old, with a history of recurrent tachycardias, refractory to pharmacological treatment. An electrophysiological study demonstrated that the mechanism of their arrhythmias was a nodal reentry. In the same session one of the mapping catheters was changed by a fulguration one and radiofrequency was applied, using a variation of the technique described by Jackman. In both, the slow pathway was modified or blocked with definitive interruption of the nodal reentry circuit and preservation of atrioventricular conduction.

[Thromboangiitis obliterans (Buerger's disease). Study of 41 cases]

BACKGROUND

The aim of this study was to know the prevalence, clinical and immunological characteristics and evolution of thromboangiitis obliterans.

METHODS

Between 1982-1990 41 cases of thromboangiitis obliterans were diagnosed from among 373,899 patients registered (11/100,000) according to the clinical and arteriographic criteria. Of these 41 cases 40 were males with mean age 36 +/- 7 years (mean +/- SD) with only two cases being over 45 years of age. In 40 cases was followed for 44 +/- 29 months (mean +/- SD).

RESULTS

All the patients had ischemia of the lower limbs, 34% of the upper limbs, 39% superficial thrombophlebitis, 53% Raynaud's phenomenon, 5% mesenteric ischemia, and 7% myocardial infarction. In 30 symptomatic patients anticardiolipin antibodies were determined and one patient was positive for IgG antibodies. In the 23 patients in whom HLA and anticollagen antibody studies were performed a significant increase was found in HLA-B35, HLA-B40 and type VI denaturalized anticollagen antibodies compared to controls. In general the evolution was progressive when the patients continued smoking and favorable when tobacco was given up except in 2 cases who stopped smoking and in whom the disease progressed and death occurred. The total number of patients who died during follow up was 3 (7%), 2 due to mesenteric ischemia and the third during i.v. infusion of PGE1.

CONCLUSIONS

The results demonstrate that thromboangiitis obliterans is a rare disease in Spain. The involvement of visceral arteries is not very infrequent with worse prognosis when the mesenteric arteries are involved. There is a significant increase of determined HLA antigens and anticollagen antibodies in the patients with thromboangiitis obliterans.

[The progression of a postinfarct interventricular communication: an echocardiographic follow-up]

An 80-year-old female patient presented rupture of the interventricular septum as complication of acute anteroseptal myocardial infarction. Serial echocardiographic studies documented progressive increase in size of the apical defect over 16 hours. This observation highlights a potential hazard if surgical repair is deferred to "stabilize" hemodynamically the patient before the intervention.

Implications of the coronary vascular endothelium as mediator of the vasodilatory and dromotropic actions of adenosine

Recent studies have shown that the vasodilatory response of adenosine is partially endothelium dependent. Therefore, to further characterize the physiologic role of the vascular endothelium as mediator of adenosine's cardiovascular effects, we have examined in isolated perfused guinea-pig hearts the dromotropic and vascular effects of adenosine in the presence of the adenosine antagonist, XAC, covalently conjugated to latex microspheres of 0.07 microns diameter. Our results demonstrate that intravascular infusion of the microsphere XAC conjugates abolishes the vasodilatory and negative dromotropic effects of infused adenosine, and inhibits the dromotropic effects of hypoxia. As these particles because of their size remain intravascularly confined, we conclude that the dromotropic and vasodilatory effects of exogenous adenosine, and the dromotropic effects of hypoxia (endogenous adenosine), arise from the intravascular adenosine compartment acting by way of the vascular endothelium. In addition, while neither the temporal course of vasodilation nor the steady state of vasodilation caused by hypoxia were influenced by unconjugated XAC, our results do show that the microsphere XAC conjugate increases the time necessary for maximum vasodilation to occur during hypoxia.

Widespread dermatophytosis due to Microsporum (Trichophyton) gallinae in a patient with AIDS--a case report from Spain

We report the case of a 25-year-old, HIV-positive patient (group IV, A, C2 clinical stage) with a widespread dermatophyte infection. He was a male gypsy with a known history of intravenous drug abuse. After an episode of cerebral toxoplasmosis for which he was treated with systemic steroids (because of cerebral oedema) he developed, over 16 days, a remarkably extensive ringworm of the trunk due to an unusual zoophilic dermatophyte, Microsporum (Trichophyton) gallinae. Human infection with this dermatophyte species is unusual: there are as few as seven proven reported cases, all of whom had localized lesions. This is the first widespread and severe case reported in man and also the first reported from Spain.

Heterogeneity and sampling volume dependence of epicardial adenosine concentrations

Rapid steady-state estimates of interstitial fluid (ISF) adenosine concentrations (ADOi) in the left ventricular epicardium of anesthetized dogs were obtained by the epicardial porous disc (EPD) method described herein. Because of the high temporal and spatial resolution of this method, it was ideally suited to test the hypothesis that ADOi may vary in these domains. Variance in steady-state EPD solute concentrations was quantified statistically by the coefficient of variation (CV = standard deviation/mean), which we used as an index of heterogeneity. A significant temporal variation in steady-state EPD adenosine concentrations was observed when samples were sequentially collected from one epicardial location (CV = 42.9 +/- 3.5%). When steady-state sample pairs (n = 45) were collected simultaneously from two distinct epicardial locations, a 2.6 +/- 0.3-fold mean difference in their respective adenosine concentrations was measured. About 25% of this variation was inherent in procedural methodology, based on the variability of steady-state EPD concentrations of extracellularly-equilibrated 14C sucrose (CV = 12.7 +/- 1.2%) and the variability of steady-state concentrations of both solutes measured using in vitro preparations (mean CV = 9.7 +/- 1.2%). Thus, we contend that endogenous myocardial ISF adenosine is temporally and perhaps spatially heterogeneous. Our estimates of steady-state ADOi obtained with the EPD method ranged from 0.47 to 0.99 microM. Using modifications of the EPD technique and the epicardial chamber, we also demonstrated that the adenosine concentration in 'steady-state' epicardial samples is reduced when the volume/surface area ratio of the sample buffer is increased. We hypothesize that sampling-induced decreases in steady-state ADOi underlie these observations, because losses of ISF adenosine to high volumes of sample buffer can be greater than the myocardial cells are capable of replacing. However, with the very low volume/surface area ratio of a single EPD (7.5 microliters/cm2), steady-state ADOi may remain constant during sampling, allowing for accurate determinations of ADOi with this method.

Functional role of intravascular coronary endothelial adenosine receptors

The endothelium is relatively 'impermeable' to adenosine. In addition, infusion of adenosine deaminase and transient infusion of large size adenosine agonists (molecular weight 100 kD) which are confined to the intravascular space depress effects of endogenous adenosine and retain physiologic activity respectively. Accordingly, the concept that intravascular adenosine may exert some of its action on the capillary lumen was tested by coupling the agonists: N6-([aminoethylamino]carbonyl)methylphenyladenosine (ADAC) and N6-octylamine adenosine (NOA) to carboxylated latex microspheres (0.07 microns diameter); thus, insuring their intravascular confinement. Our results demonstrated that sustained infusion of these particles into isolated saline perfused guinea pigs hearts caused a decrease in coronary vascular resistance, ventricular contraction, spontaneous ventricular rhythm, inhibition of auricular ventricular transmission and glycolytic flux. These effects were reversible and specific since microspheres without purines had no effect and the adenosine antagonist sulphophenyltheophylline blocked these responses. Furthermore, the effects were not the result that during the passage of the sphere-agonist complex through the heart the covalent bond hydrolyzed, releasing free agonist. Our data indicate that selective activation of intravascular coronary purine receptors may cause the release of endothelial bioactive messengers that regulate the function and metabolism of vascular and cardiac cells.

Regulation of glycolytic flux by coronary flow in guinea pig heart. Role of vascular endothelial cell glycocalyx

Hemodynamic forces continuously act on endothelial cell lining of blood vessels. Blood flow, perfusing pressure, and shear stress are known to induce the release of bioactive substances from the endothelium. Furthermore, coronary flow (CF) is a well-known stimulant of myocardial contraction. Our concern was whether other Ca(2+)-dependent responses like glycolytic flux (Gf) were also CF dependent. For this purpose, isolated guinea pig hearts were perfused with a medium containing 5 mM 3-[3H]glucose, and the 3H2O released during perfusion was measured as an index of Gf. Changes in CF within the 3- to 25-ml/min range resulted in linear increase of Gf. This stimulatory effect of CF was also observed in K(+)-arrested hearts. In addition, increasing shear stress on addition of dextran to the perfusing solution (5% and 10% wt/vol), while keeping CF constant, also stimulated Gf. We hypothesized that endothelial cell membrane glycocalyx may act as sensor to this stimuli. Thus one would expect that substances acting on these structures (enzymes heparinase, hyaluronidase, or chondroitinase or the lectin concanavalin A) when added to the perfusate might inhibit the CF-induced Gf. The results showed that concanavalin A and heparinase inhibited the Gf-CF-induced response, whereas chondroitinase and hyaluronidase had no effect. These findings suggest that there may be a selective effect of these agents affecting the Gf response to CF. Our data suggest that CF stimulates Gf through shearing forces acting on specific endothelial glycocalyx component(s). Therefore, deformation of these components could result in the transduction of physical signals into release of chemical messengers that act on the biochemical machinery of underlining parenchymal cells.

Selective interactions between different species of mycorrhizal fungi and Rhizobium meliloti strains, and their effects on growth, N2 -fixation (15 N) and nutrition of Medicago sativa L

Three isolates of vesicular-arbuscular (VA) mycorrhizal fungi, belonging to the species Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe, G. fasciculatum (Taxter sensu Gerd.) Gerd, and Trappe, and G. caledonium (Nicol. and Gerd.) Trappe and Gerd, were inoculated in dual combinations with six strains of Rhizobium meliloti with the aim of testing these combinations for functional compatibility with their common host plant, the legume Medicago sativa L. Symbiotic efficiency (promotion of plant growth and N and P nutrition) was found to be dependent on the particular combination of Rhizobium strain and Glomus species indicating selective and specific compatibilities between strains and isolates of the two types of microsymbiont, but also between them and the common host plant. Observed effects on plant growth were in general, though not always, related to the extent of VA mycorrhizal colonization. Although the different mycorrhizal and/or rhizobial treatments produced different effects on plant growth, the rate of nodule formation on M. sativa roots remained constant. Most mycorrhizal treatments increased the concentration and/or content of N in plant shoots but effectiveness was in the order: G. fasciculatum > G. mosseae > G. caledonium. In some cases, this increase in N-content may be a consequence of a P-mediated stimulation of N₂ -fixation by VA mycorrhiza, as ascertained using ¹⁵ N. In other instances, however, the increase seems to reflect a VA mycorrhizal-mediated enhancement of N-uptake from soil. VA mycorrhizal inoculation decreased the concentration of Ca and Mg in plant shoots and a buffering effect of VA mycorrhiza in situations of nutrient excess in soil is proposed.

Syncope: etiology, prognosis, and relationship to age

Syncope is a common and particularly troublesome problem in the elderly population. In a series of 146 patients admitted for syncope to an acute care hospital in Chile during a 4-year period, 2/3 (68%) were aged 65 years and older. A specific etiology could be established in 62%, and 3/4 of these were cardiovascular in origin. Diagnosis was established entirely on history, physical examination, resting ECG, and 24-hour cardiac monitoring in most cases but in some, more sophisticated measures (i.e., echocardiography, electrophysiologic studies, blood tests, EEG) were needed, and mostly to confirm clinically suspected problems. In-hospital mortality was 2.1% and mortality at the end of the approximately 2-year follow-up period was 18.1%. Mortality was higher for persons over age 65 than for younger persons (23.9% vs 2.3%), and for persons with cardiovascular syncope than for persons with other kinds of syncope (28.3% vs 8.9%). This study confirms the particular lethality of syncope in the elderly population and outlines a relatively simple strategy with which most syncope patients can be diagnosed without resorting to expensive procedures.

[An epidemiological and immunological study of human immunodeficiency virus infection in the southern area of Madrid]

The clinical characteristics and immunological parameters are characterized in different groups of infection by human immunodeficiency virus (HIV) in patients infected by HIV, and the prognostic markers of survival in patients diagnosed of acquired immunodeficiency syndrome (AIDS). This study was carried out in 312 patients from June 1984 to March 1989. The most common risk group was intravenous drug addicts (IVDA) 80.9%. We observed that during the last years there was an increase in the number of cases of heterosexual transmission. Through follow up, 17.6% of patients developed acquired immunodeficiency (AIDS). The incidence rate for AIDS was higher amongst homosexuals than IVDA (35.4/14.6). Esophageal candidiasis and extrapulmonary tuberculosis were the AIDS indicators most frequently encountered. Once the study period was over, with a follow up of 19.3 +/- 3.4 months, the probability of survival after 12 months was 70 +/- 0.07% and after 24 months was 42% +/- 0.09%. The risk group (homosexuals), the appearance of a neoplasia as the first diagnosis of AIDS, and the immunological parameters (CD3 less than 500, CD4 less than 400, CD4/CD8 ratio less than 0.5 and total lymphocyte count of less than 1700 were the markers with worst prognosis which correlated with survival rates (p less than 0.01). We confirmed that when comparing immunologic parameters amongst HIV infection groups, IgA levels were higher (p less than 0.05); the total number of lymphocytes, the number of helper lymphocytes and the CD4/CD8 ratio were lower (p less than 0.01) in IV and AIDS group with respect to group II and III, in patients with AIDS with respect to group IV-non-AIDS and in those who died with relation to AIDS.

Interstitial adenosine in guinea pig hearts: an index obtained by epicardial disks

Epicardial porous disks were used to estimate left ventricular interstitial fluid adenosine in the isolated guinea pig heart perfused at constant flow. To validate this technique, adenosine was infused with 0.5 microM dipyridamole and 5 microM erythro-4-(2-hydroxy-3-nonyl)adenine hydrochloride (EHNA) to inhibit adenosine uptake and deamination, respectively. Under these conditions, with 6 or 12 microM adenosine in the arterial infusate, the venous and steady-state left ventricular disk adenosine values equaled those of the perfusion fluid, reflecting the expected equilibration between vascular and left ventricular interstitial fluid (disk) compartments. The concentration of endogenous adenosine in the interstitial fluid as estimated by the epicardial disks under control conditions was 0.28 +/- 0.03 microM with a concomitant coronary sinus concentration of 0.004 +/- 0.001 microM. We conclude that a marked adenosine gradient exists between the interstitial fluid and the vascular space and that disk adenosine measurements provide a useful index of left ventricular interstitial fluid adenosine.

Nitriles and isonitriles as interferents in cyanide determination in polluted waters

The interference of nitriles and isonitriles in cyanide determination was studied using the pyridine-barbituric acid direct spectrophotometric method or the same method after distillation of the sample, a microdiffusion-potentiometric (ion-selective electrode) also being used. Phenylacetonitrile, benzonitrile, acrylonitrile, iminodiacetonitrile and acetonitrile were tested as nitriles. Benzyl isocyanide butyl isocyanide and 1-[(isocyanomethyl)sulphonyl]-4-methylbenzene were assayed as isonitriles. It can be concluded that both nitriles and isonitriles should be considered as interferents in all the methods of cyanide determination studied. The level of interference generally increases with the ratio of interfering compound to cyanide and is greatest for low cyanide concentrations.

Hodgkin's disease in patients with antibodies to human immunodeficiency virus. A study of 22 patients

The experience of 22 Hodgkin's disease (HD) patients with human immunodeficiency virus type I (HIV) antibodies, collected from a cooperative study of six hospitals during 1984-1989 is presented. Young men (average age, 27.6 years) with a high incidence of intravenous drug abuse (86%) were found. The status of the HIV infection at diagnosis of HD was: four patients, acquired immune deficiency syndrome (AIDS); eight patients, persistent generalized lymphadenopathy (PGL); and ten patients, asymptomatic. The natural history of HD was unusual, with a high incidence of B symptoms (81%), advanced Stages III to IV (90%), bone marrow invasion (50%), cytopenias before treatment (45%), opportunistic infections (68%), and aggressive histologies. A decreased response to chemotherapy with poor marrow tolerance and a significant decrease in survival, 18 months, was observed. The AIDS and cytopenias pretreatment were associated with a shorter statistically significant survival, which defines the importance of immunodeficiency in HD prognosis. Complete remission after treatment was a factor that contributed to a longer statistically significant survival. The PGL or asymptomatic patients survived longer but also had a poor course, and five of them had AIDS criteria during evolution. A high incidence of HD in relation to non-Hodgkin's lymphoma (NHL) in patients with HIV infection in the six cooperating hospitals was found. Criteria for considering HD as an AIDS-associated lymphoproliferative disease in our environment are discussed.

Time-dependent effects of theophylline on myocardial reactive hyperaemias in the anaesthetized dog

1. The effects of a loading dose of theophylline (5 mg kg-1 i.v.) on the hyperaemias resulting from short-term (15 and 30 s) interruptions in coronary blood flow and intracoronary adenosine were studied at given intervals over a 2 h period in the anaesthetized dog. 2. These hyperaemic responses were affected differently by theophylline and each effect was time-dependent. The reactive hyperaemic response progressively decreased after drug delivery, reaching 46% of control at 2 h. In contrast, after a maximal attenuation to 23% of control 5 min after theophylline, the hyperaemia resulting from intracoronary adenosine progressively increased over the same period, reaching 64% of control 2 h after the loading dose. 3. Two-compartment model results based on plasma theophylline measurements and the time course of theophylline accumulation in pericardial infusates, suggested that complete drug distribution throughout the heart may require at least 20 min following a single intravenous dose. 4. If it is assumed that theophylline blocks coronary vascular adenosine receptors, these pharmacokinetics are consistent with the time-dependent pattern of response attenuation we observed for the adenosine-induced hyperaemias, but they cannot entirely explain the pattern of response attenuation observed for the occlusion-induced hyperaemias. The continued increase in attenuation of this response after complete drug distribution suggests an additional pharmacodynamic action of theophylline. 5. We conclude that a single therapeutic dose of theophylline results in distinct time-dependent pharmacological effects with respect to the ability of the coronary vasculature to dilate in response to temporary interruptions in oxygen supply and in response to exogenously administered adenosine. These effects deserve consideration in both experimental studies in which adenosine antagonists are used to assess adenosine action in vivo, and in clinical practice where theophylline pharmacotherapy for pulmonary disorders is commonplace.

[Syncope: recurrence and prognosis during 2 years]

We followed up 143 patients that had been admitted to intensive care units of a general hospital with syncope. 127 patients (89%) remained in follow up for a mean of 24 months (range 3 to 54 months). There were 70 men and 57 women and the mean age was 71.5 years. Recurrences were observed in 21 patients (17%) and were similar for patients whose syncope had a cardiovascular origin (10%), non cardiovascular origin (25%) or an undetermined cause (18%). Mortality from cardiac or vascular causes was 20% in the cardiovascular origin group, and 5 and 4.2% in the other groups, respectively (p less than 0.005). Recurrence did not influence mortality. A history of hypertension, cerebrovascular accidents and ventricular arrhythmias was associated to higher mortality risk (p less than 0.05).

Adenosine stimulates glycolytic flux in isolated perfused rat hearts by A1-adenosine receptors

This study was designed to assess the role of adenosine in the regulation of exogenous glucose utilization by myocardium. Perfusion of isolated rat hearts with buffer containing D-[3-3H]glucose and analysis of the coronary effluent for 3H2O production was used as an indicator of glycolytic flux. Initially, glycolytic flux was determined during five different conditions: 1) normoxia; 2) normoxia plus 100 microM adenosine; 3) normoxia plus 100 microM adenosine and 10 microM 8-(sulfophenyl)-theophylline (SPT), an adenosine receptor antagonist; 4) hypoxia; and 5) hypoxia plus 10 microM SPT. Both adenosine and hypoxia produced an approximate threefold increase in glycolytic flux that was attenuated by adenosine receptor blockade with SPT. Next, hearts were perfused during normoxic conditions with various concentrations of either R-phenylisopropyladenosine (PIA), an A1-adenosine receptor agonist, or 5'-N-ethylcarboxamidoadenosine (NECA), an A2-adenosine receptor agonist. Significant increases in glycolytic flux occurred with PIA, whereas NECA treatment resulted in only a marginal stimulation of glycolytic flux. These data provide evidence that: 1) exogenous adenosine stimulated glycolytic flux in the normoxic myocardium; 2) endogenous adenosine stimulated glycolytic flux during hypoxia; and 3) the effect of adenosine on glycolytic flux was mediated by interaction with A1-adenosine receptors.

Adenosine formation and release by embryonic chick neurons and glia in cell culture

Adenosine formation and release were studied in 48-h-old cultured ciliary ganglia and confluent peripheral and CNS glial cultures from embryonic chicks. Metabolic poisoning induced by 30 mM 2-deoxyglucose and 2 micrograms/ml oligomycin reduced ATP concentration by 90%. An increase in adenosine accounted for 15-40% of the fall in ATP. Dilazep (3 X 10(-6) M), a nucleoside transport inhibitor, decreased both incorporation of adenosine (an index of nucleoside transport) and release of adenosine by 80-90%. Dilazep trapped the newly formed adenosine intracellularly. A concentration of alpha, beta-methylene ADP that inhibited ecto-5'-nucleotidase by 80-90% did not alter the concentration of adenosine or AMP in neurons, glia, or medium. The results demonstrate that adenosine is formed intracellularly and exported out of the cell via the nucleoside transporter. The participation of ecto-5'-nucleotidase was excluded.

[Syncope: general characteristics and its relation to age]

We retrospectively analyzed the clinical data of 146 patients admitted to a general hospital with the diagnosis of syncope. A definite or highly likely cause was identified in 91 patients (62%). These were of cardiovascular origin in 78%: conduction defects (31), sinus node disease (9), obstructive causes (8), ventricular arrhythmia (8), ischemia (5) and miscellaneous (14). A non cardiovascular origin was present in 22% of patients: intoxication (7), hysteria (5), hypoxemia (3), vasovagal (2), gastrointestinal bleeding (2) and 2 others. The final diagnosis in patients with a known cause was established by the history and physical examination in 16, the ECG in 42, Holter 9, ECG monitoring in ICU 8 and echocardiogram 6. No difference in the distribution of causes was present between patients below or above 65 years of age. In hospital mortality was 2%.

[Histiocytosis of Langerhans cells: a study of 40 cases]

Forty cases of histiocytosis of Langerhans' cells (26 children and 14 adults) were evaluated; 20 were localized forms (with single or multiple bone involvement); another 20 were generalized forms, with organic dysfunction (lung, liver, hemopoietic system) in 7 children. This feature has a poor prognostic significance, as shown by the fact that 3 of these 7 patients died. In 3 patients single skin involvement was found, with spontaneous recovery one month after the diagnosis in one; in one case the single involvement was lymphadenopathic, associated to Hodgkin's lymphoma, and in another it was hypothalamic. These cases of single involvement have been followed up between 1 and 4 years. In 4 of 7 patients with generalized disease a reduction of OKT8 with an increased OKT4: OKT8 ratio was found, as reported in other cases from the literature. This finding gives support to an immunological rather than neoplastic basis for the disease. In all 40 cases the diagnosis was morphological, with positive staining for S-100 protein in 38.

The effect of local infusion of adenosine and adenosine analogues on local cerebral blood flow

The purpose of this study was to determine the effects of local infusion of adenosine (ADO) and non-metabolized ADO analogues on local cerebral blood flow (CBF) and interstitial fluid (ISF) ADO levels. The brain dialysis technique was used to (a) deliver drugs locally to brain tissue, (b) estimate cerebral ISF ADO levels, and (c) measure local CBF (hydrogen clearance). Dialysis probes were implanted bilaterally in the caudate nuclei of ketamine-anesthetized rats. The probe on one side was perfused with artificial CSF while the contralateral probe was perfused with artificial CSF containing ADO (n = 5), or the ADO agonists 2-chloroadenosine (2-CADO; n = 4) or 5'-N-ethylcarboxamide adenosine (NECA; n = 4). When ADO was included in the artificial CSF at 10(-5), 10(-4), or 10(-3) M, a 30% increase in local CBF was detected only with 10(-3) M ADO. During perfusion with ADO, dialysate inosine and hypoxanthine levels increased, indicating that the cells adjacent to the probe metabolized the exogenous ADO. With 2-CADO included in the artificial CSF at 10(-6), 10(-5), or 10(-4) M, local CBF increased 18, 131, and 201%, respectively. Perfusion with artificial CSF containing 10(-7), 10(-6), or 10(-5) M NECA resulted in a 35, 112, and 187% increase in local CBF, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Visceral leishmaniasis (kala-azar) as an opportunistic infection in patients infected with the human immunodeficiency virus in Spain

In an area endemic for visceral leishmaniasis, 16 patients with human immunodeficiency virus (HIV) infection developed the disease. All belonged to populations at risk for AIDS (15 were intravenous drug abusers). Five patients fulfilled the criteria for full-blown AIDS, and two more fulfilled them after diagnosis of leishmaniasis. All presented with the classic manifestations of visceral leishmaniasis, but leishmania serology was negative in 15 patients (93%). Leishmania donovani amastigotes were identified in the bone marrow in all cases. Most patients responded initially to treatment with pentavalent antimonial drugs, but seven (43%) followed a chronic course, with multiple relapses in five, despite alternative treatments. Visceral leishmaniasis occurred in patients with different levels of depression of the CD4 to CD8 lymphocyte ratio. Mortality was 37% (six patients) and was independent of the chronic-relapsing course of the disease. In no case was leishmaniasis the primary cause of death. Our data establish that visceral leishmaniasis is an opportunistic infection in HIV-infected patients, and we suggest that in endemic areas it should be considered an indicator disease for the diagnosis of AIDS.

Inositol phospholipid metabolism during and following synaptic activation: role of adenosine

The metabolic pathway of inositol phospholipids represents a series of synthetic and hydrolytic reactions with inositol as a by-product. Hence, the rate of [3H]inositol release from prelabeled phospholipids can be used as a reflection of activity of this pathway. In the frog sympathetic ganglion prelabeled with [3H]inositol, we studied the effect of synaptic activity (orthodromic stimulation) on release of 3H-label into the medium. This release was interpreted as [3H]inositol release. The value was low at rest and increased significantly by 32% during orthodromic stimulation (20 Hz for 5 min). However, on cessation of the stimulation, [3H]inositol release increased rapidly by 148% and remained elevated for at least 45 min. This increase in [3H]inositol release during and after the stimulation period was reduced by suffusion of the ganglia with adenosine. We hypothesized that synaptic activation releases a long-lasting stimulatory agonist and a short-lasting inhibitory (adenosine) agonist or agonists affecting [3H]inositol release. To demonstrate the presence of a stimulatory agonist, two sympathetic ganglia were used. One was prelabeled with [3H]inositol, and the other was not. The two ganglia were placed together in a 5-microliter droplet of Ringer's solution containing atropine. Orthodromic stimuli applied to the nonlabeled ganglion elicited release of [3H]inositol from the nonstimulated ganglion. To test whether the adenosine formed during orthodromic stimulation inhibits [3H]inositol release, we destroyed endogenous adenosine by suffusion of the ganglia with adenosine deaminase during the stimulation period. We found that adenosine deaminase induced large increases in [3H]inositol release during the stimulation period, in contrast to an increase seen only during the poststimulation period when adenosine deaminase was omitted. Because [3H]inositol release is assumed to parallel changes in content of inositol phosphates, we anticipated no changes of the levels of these compounds during orthodromic stimulation. However, measurements showed that levels of inositol phosphates and inositol phospholipids were all elevated except for phosphatidylinositol 4-phosphate. On termination of the stimulus, they remained elevated, with a further increase in levels of inositol trisphosphate and phosphatidylinositol 4-phosphate. We conclude that endogenous adenosine inhibits [3H]inositol release, possibly by modulating several of the steps of the inositol phospholipid pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain interstitial adenosine and sagittal sinus blood flow during systemic hypotension in piglet

We sampled, using the brain dialysis technique, interstitial fluid adenosine from the frontal cortex of newborn piglets subjected to hemorrhagic hypotension while measuring sagittal sinus blood flow, cerebrovascular resistance (CVR), and cerebral O2 delivery. In group 1 (n = 8), MABP was reduced in successive steps from 76 to 30 mm Hg with decrements of approximately 10 mm Hg. At 60 mm Hg, CVR decreased by 19% (p less than 0.001), but sagittal sinus blood flow and interstitial fluid adenosine remained unchanged. At 50 mm Hg, both sagittal sinus blood flow and CVR decreased by 19% (p less than 0.001) and interstitial fluid adenosine rose 4.7-fold (p less than 0.05). At 40 and 30 mm Hg, sagittal sinus blood flow decreased further but CVR remained steady, whereas interstitial fluid adenosine rose 10- and 16-fold, respectively. In group 2 (n = 7), an abrupt reduction of MABP from 80 to 47 mm Hg produced no change in sagittal sinus blood flow and a 29% decrease in CVR (p less than 0.01). Interstitial fluid adenosine increased twofold (p less than 0.01). In group 3 (n = 7), an abrupt reduction of MABP from 79 to 40 mm Hg decreased sagittal sinus blood flow and CVR by 24 and 30%, respectively (p less than 0.01). Interstitial fluid adenosine rose threefold (p less than 0.01). In groups 1, 2, and 3, the increases in interstitial fluid adenosine accompanied decreases in cerebral O2 delivery. In group 4 (n = 7), artificial CSF with a PO2 of 152 mm Hg was perfused through the brain dialysis cannula during graded hypotension.(ABSTRACT TRUNCATED AT 250 WORDS)

Release of purines from postsynaptic structures of amphibian ganglia

Isolated sympathetic paravertebral ganglia of the frog were incubated for 1 h with [3H]adenosine. Then, after washout of excess label, the contribution of pre- and post-synaptic activation on the release of 3H-labeled purines was studied. The ganglion was superfused with Ringer's solution at room temperature, and extracellular electrodes were used for stimulation and recording. Preganglionic stimulation enhanced overall release of 3H-labeled purines. At rest, the release of 3H-labeled purines per minute represented 0.62 +/- 0.02% of the total 3H-label in the ganglion, and this fraction increased depending on the frequency of orthodromic stimulation. Analyses of the effluent from resting and stimulated ganglia showed that in both cases the nonnucleotide fractions constituted greater than 97% of the total counts in the medium: adenosine (58.4 +/- 10.1%); inosine (31.7 +/- 12.9%); hypoxanthine (7.1 +/- 2.4%); and AMP, ADP, and ATP together (1.6 +/- 0.9%) (n = 11). Nucleotides were released, but their levels were not increased significantly during stimulation. Inclusion of ectophosphatase inhibitors slightly enhanced nucleotide release (from 1.1 +/- 0.5 to 1.8 +/- 0.7%; n = 5) but did not alter the amount of nucleosides. Hence, nucleosides are the main products released by the ganglion and do not arise from hydrolysis of extracellular ATP. Preganglionic stimulation enhanced release of labeled purines, which was frequency dependent from 1 to 20 Hz. Atropine (2 microM) and tubocurarine (150 microM) totally blocked the release of 3H-labeled purines associated with preganglionic stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral blood flow and interstitial fluid adenosine during hemorrhagic hypotension

This study was designed to assess the role of adenosine in autoregulation of cerebral blood flow (CBF) with the use of the brain dialysis technique to sample cerebral interstitial fluid (ISF) and hydrogen clearance to measure local CBF in ketamine-anesthetized rats. In group 1 (n = 11), animals were hemorrhaged to reduce mean arterial blood pressure (MABP) from control levels (MABP = 101.1 +/- 2.6) to 80, 70, 60, 50, 40, and 30 mmHg. Cerebral autoregulation was evidenced by no significant decrease in CBF until MABP decreased to 60 mmHg. However, dialysate adenosine concentration did not increase until MABP decreased to 50 mmHg. In group 2 (bilateral dialysis; n = 11), in which the left carotid artery was ligated before reductions in MABP, left-side dialysate adenosine concentration increased at a MABP of 70 mmHg. In group 3 (bilateral dialysis; n = 6), one dialysis probe was perfused with artificial cerebrospinal fluid containing 10(-3) M 8(p-sulfophenyl)theophylline (8-SPT), an adenosine receptor antagonist, during reduction of MABP to 50 mmHg. Although there were similar reductions in CBF with or without adenosine receptor blockade, dialysate adenosine concentration was greater on the side of locally infused 8-SPT at a MABP of 50 mmHg. These data suggest that adenosine is not responsible for cerebral autoregulation at blood pressures greater than 50 mmHg but may contribute to the decrease in cerebral vascular resistance observed at arterial pressures below the autoregulatory range.

Adenosine stimulates glucose uptake in the isolated rat heart

Adenosine (Ado) is a potent coronary vasodilator. Recent studies suggest that Ado may also have an important effect on myocardial carbohydrate metabolism. To determine whether Ado has a direct effect on myocardial glucose uptake, a recirculating, constant-flow, isolated rat-heart preparation was used. The hearts were perfused with Krebs-Henseleit buffer solution with an initial glucose concentration of 11 mmol/L. A control group was compared with hearts treated with Ado infusions (50 and 100 micrograms/min) or insulin (100, 200, and 300 microU/ml). In a separate series of experiments, nitroprusside was used to evaluate the effect of a nonspecific coronary vasodilator. The rate of glucose uptake was calculated as the amount of glucose removed from the perfusate normalized for heart weight and time. Developed pressure (DP) was assessed with an intraventricular balloon, and the coronary perfusion pressure (CPP) was monitored. At the end of 1 hour, the hearts were freeze-clamped and adenine nucleotide content was measured with HPLC. Ado treatment increased glucose uptake by 80% and 140%, respectively, at the two infusion rates (p less than 0.001). Myocardial adenosine triphosphate content was 18% and 26% higher in the Ado-treated hearts than in the controls (p less than 0.001). Ado also decreased the mean DP by 30% and 36% (p less than 0.001) and decreased CPP by 10% and 22%, respectively (p less than 0.001). Insulin increased glucose uptake in a similar dose response fashion but had no effect on myocardial nucleotide content, DP, or CPP. Nitroprusside decreased CPP but had no effect on glucose uptake, adenine nucleotide content, or DP. These results suggest that Ado may have a direct effect on glucose uptake independent of its properties as a coronary vasodilator.

Release of adenosine from pig aortic endothelial cells during hypoxia and metabolic inhibition

The purpose of this study was to determine the effects of acute hypoxia on the ATP content of, and release of adenosine from, cultured endothelial cells. Pig aortic endothelial cells grown on plastic dishes or on microcarrier beads were incubated in physiological saline and gassed to achieve normoxia (media PO2 = 80-85 mmHg) or hypoxia (media PO2 = 2-12 mmHg) in the presence and absence of glucose and dipyridamole. Acute hypoxia did not significantly augment adenosine release from cells but did appear to decrease the reuptake of adenosine by cells. Hypoxia of a longer duration (3 h) led to ATP degradation and increased adenosine release when glucose was absent from the incubating medium, but not otherwise. Similarly, incubation of cells with NaCN in a glucose-free medium led to an increase in extracellular adenosine accumulation, whereas NaCN in the presence of glucose did not increase the accumulation of adenosine above the control level. The results suggest that the adenine nucleotide metabolism of cultured endothelial cells is not acutely sensitive to hypoxia or to inhibition of oxidative metabolism and can be maintained by glycolysis.

Estimates of left ventricular interstitial fluid adenosine during catecholamine stimulation

The hypothesis that changes in myocardial interstitial fluid (ISF) adenosine (Ado) concentrations couple coronary blood flow (CBF) with myocardial oxygen need is still controversial. Measurements of Ado in cardiac tissue, coronary sinus plasma, and pericardial infusates have commonly been used as indexes of ISF Ado, but recent studies have highlighted the potential invalidity of many of the assumptions underlying these sampling methods. With the use of an epicardial chamber (EC) to contain a small volume of buffer on the undisturbed left ventricular epicardium of anesthetized open-chest dogs, estimates of ISF Ado can be obtained without invoking these assumptions. In experiments designed to validate our method and investigate the role of Ado in the regulation of CBF during myocardial catecholamine stimulation, we found that endogenous Ado accumulated in the EC exponentially and attained constant steady-state concentrations, ranging from 75 to 125 nM, within 4 min. Intravenous infusions of two catecholamines increased steady-state EC Ado concentrations twofold, but did not affect Ado influx kinetics. We conclude that the EC technique yields more direct estimates of steady-state ISF Ado concentrations than previously available and that ISF Ado is involved in the mediation of the hyperemia accompanying myocardial catecholamine stimulation.

Intracellular adenosine formation and its carrier-mediated release in cultured embryonic chick heart cells

Adenosine formation and release was examined in 48 hr old primary cultures of chick ventricular myocytes. Dilazep greater than hexobendine greater than dipyridamole inhibit incorporation of adenosine into chick embryonic heart cellular nucleotides in a concentration dependent manner. A combination of 30 mM 2-deoxyglucose and 2 micrograms of oligomycin/ml reduces the ATP content of the cells by 71% in 10 min. This change is accompanied by an increase in total adenosine concentration of 3.4 nmoles/10(7) cells in 10 min. Although the ATP concentration is not altered during hypoxia (95%N2/5%CO2), adenosine concentration increases by 0.52 nmoles/10(7) cells in 30 min. When nucleoside incorporation is inhibited by 85-90% by dipyridamole, dilazep or hexobendine, efflux of adenosine decreases by 70-90%, and 60-90% of the newly formed adenosine is trapped inside the cells compared to 10% in the absence of the transport inhibitors. alpha, beta -Methylene ADP inhibits the ecto 5'-nucleotidase activity by 91 +/- 6% but does not inhibit adenosine formation or alter its distribution between cells and medium, thus ruling out the involvement of this enzyme in adenosine formation. We conclude that adenosine is formed intracellularly during 2-deoxyglucose and oligomycin-induced ATP degradation and during hypoxia and that the nucleoside is released via the symmetric nucleoside transporter.

[Biological significance of the endogenous secretion of insulin in response to breakfast in diabetic children]

In 20 insulin dependent diabetics and in eight age-matched healthy children, we have measured basally HbA1 and the plasma lipid profile; and both basally and after a standard breakfast of 400 cal, blood glucose, C-peptide (CPR), immunoreactive glucagon (IRG), growth hormone and nonesterified fatty acids (NEFA). No difference was found in the lipid profile of diabetic and non diabetic children. In diabetics basal blood glucose was significantly correlated to both basal C-peptide (r = 0.5332, p less than 0.05) and to the ratio C-peptide/glucagon (r = 0.8563, p less than 0.01). The C-peptide response to the breakfast was accompanied of a significant increase in IRG and NEFA in diabetics, while in non-diabetics there was no change in IRG and a significant decrease in NEFA levels. Diabetic children with basal C-peptide levels higher than 0.6 ng/ml had lower blood glucose levels (187 +/- 43 vs 315 +/- 20 mg/dl, p less than 0.02), but no difference in blood glucose or any other parameter was observed as a function of the increase in CPR after breakfast. From these results we conclude that the evaluation of residual B-cell function in diabetic children by measuring the C-peptide response to a provocative stimulus is not more informative than the single basal measurement of C-peptide and does not have an additional biological significance, at least in hyperglycaemic insulin dependent diabetic children.

Interstitial fluid adenosine and sagittal sinus blood flow during bicuculline-seizures in newborn piglets

Changes of interstitial fluid adenosine concentrations and effects of O2 supply on interstitial fluid adenosine were studied by the brain dialysis technique in the frontal cortex of newborn piglets subjected to bicuculline-induced seizures. The O2 supply was changed globally by changing MABP and locally by varying PO2 in the artificial CSF perfusing the dialysis cannula. Sagittal sinus blood flow (SSBF), cerebrovascular resistance (CVR), and CMRO2 were also examined in the same animals. Seizures increased interstitial fluid adenosine 7.9-fold (p less than 0.05) when ictal MABP was maintained at preictal level and perfusate PO2 was 24 mm Hg (group 1, n = 6). Interstitial fluid adenosine increased 11.8-fold (p less than 0.05) during seizures associated with moderate systemic hypotension and the low perfusate PO2 (group 2, n = 6). By contrast, seizures increased interstitial fluid adenosine three-fold (p less than 0.05) when perfusate PO2 was increased to 182 mm Hg and ictal MABP was maintained at preictal level (group 3, n = 8). When ictal MABP was elevated from the preictal level and the perfusate was rich in oxygen, seizures failed to increase interstitial fluid adenosine (group 4, n = 7). In groups 1 and 3, the increase in interstitial fluid adenosine during seizures was associated with significant increases in SSBF and CMRO2, as well as significant decreases in CVR. These data suggest that the increase in O2 supply during seizures in piglets did not match completely the increase in O2 demand and resulted in enhanced release of adenosine into the interstitial space.

Increased brain interstitial fluid adenosine concentration during hypoxia in newborn piglet

The effects of arterial hypoxia on interstitial fluid adenosine concentrations were studied in the frontal cortex and thalamus by the brain dialysis technique and in CSF from the cisterna magna of the newborn piglet. Acute hypoxia (PaO2 = 20 +/- 1 mm Hg) increased the interstitial fluid adenosine concentrations significantly from 0.68 +/- 0.29 (SEM) to 1.60 +/- 0.35 microM in the frontal cortex and from 1.03 +/- 0.32 to 2.60 +/- 0.86 microM in the thalamus (n = 8). Interstitial fluid inosine and hypoxanthine also increased significantly during hypoxia. In separate groups of piglets, the adenosine concentration in the cisterna magna CSF under normoxic conditions was 0.04 +/- 0.01 microM (n = 5), which increased significantly to 0.17 +/- 0.04 microM (n = 6) with hypoxia (PaO2 = 4.7 +/- 1.2 mm Hg). Cisterna magna CSF inosine levels did not change significantly during the severe hypoxia. Adenosine concentrations found in the interstitial space and CSF of newborn piglets under normoxic and hypoxic conditions are within the vasodilator range. These results thus suggest that in the neonatal brain adenosine may play a role in regulating blood flow during hypoxia.

Extraction of adenine nucleotides from cultured endothelial cells

The goal of this work was to find a method suitable for the extraction of adenine nucleotides from cultured vascular endothelial cells. Extraction of cell monolayers with 80% methanol in water yielded extracts with a higher content of ATP than did extraction of cells with perchloric acid, trichloroacetic acid, or boiling water. The optimal extraction solution was 80% methanol with 0.5 mM ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetic acid (EGTA) or EDTA, heated to 70 degrees C immediately before use. Extraction of nucleotides by this solution was rapid and the recovery of exogenous ATP added during the extraction process was generally greater than 90%. An aqueous methanol or ethanol solution may be applicable for the extraction of nucleotides and other metabolites from cultured animal cells, dispersed cells, and frozen, powdered tissues.

Increases in cerebral interstitial fluid adenosine concentration during hypoxia, local potassium infusion, and ischemia

This study used the brain dialysis technique to test the hypothesis that the adenosine concentration of cerebral interstitial fluid increases during situations in which cerebral oxygen supply is inadequate for oxygen demand. Sealed 300-micron hollow dialysis fibers were implanted in the caudate nucleus of pentobarbital-anesthetized rats and perfused at 2 microliter/min with artificial cerebrospinal fluid. In vitro tests indicated the recovery of adenosine, inosine, and hypoxanthine from the external medium to be approximately 20% at 2 microliter/min and close to 100% at 0.1 microliter/min. Three in vivo interventions were tested: hypoxia/hypotension (PaO2 = 41.9 mm Hg; MABP = 42.8 mm Hg; n = 9), local potassium infusion (n = 4), and cerebral anoxia/ischemia (n = 10). These interventions produced 10-, 4-, and 30-fold increases in perfusate adenosine concentration, respectively, as well as increases in perfusate concentrations of inosine and hypoxanthine. A separate group of rats (n = 9) perfused at 0.1 microliter/min yielded estimates of cerebral interstitial fluid adenosine, inosine, and hypoxanthine concentrations of 1.26, 3.30, and 7.19 microM, respectively. These results are consistent with the adenosine hypothesis for the regulation of CBF.

Uptake and release of adenosine by cultured rat aortic smooth muscle

We wanted to determine whether CO2, H+ and K+ affect the adenosine metabolism of vascular smooth muscle in a way that could account for the effects of these substances on vascular reactivity and their ability to modulate adenosine-induced vascular relaxation. Accordingly, 1-week-old cultures of rat aortic smooth muscle were incubated in phosphate-buffered saline with various [K+]'s and pH's and aerated in an incubation chamber with gases containing various proportions of CO2. Uptake was measured as 14C incorporation into cellular constituents during exposure to 2 microM [14C]adenosine. Release was measured as net extracellular adenosine accumulation. Uptake of adenosine was not significantly affected by any of the experimental maneuvers, except that it was greatly attenuated by dipyridamole (10(-5) and 10(-4) M) and transiently enhanced by the low CO2 levels. Adenosine release, however, was depressed by lowering atmospheric CO2 (0% vs 5%) and also by normocapnic acidosis (pH 6.8 vs pH 7.4). We conclude that vascular smooth muscle in culture releases adenosine at a rate that might have vasoactive significance in vivo. Furthermore, some of the vascular actions of CO2 and H+, but not those of K+, may be partially explained by their effects on vascular smooth muscle's adenosine metabolism.