Effect of propentofylline (HWA 285) on extracellular purines and excitatory amino acids in CA1 of rat hippocampus during transient ischaemia.

1. The adenosine uptake blocker propentofylline (HWA 285) has previously been shown to protect hippocampal CA1 pyramidal cells from ischaemia-induced delayed neuronal death. The influence of propentofylline, on the extracellular concentrations of purines, aspartate and glutamate in the CA1 of the rat hippocampus during transient forebrain ischaemia was investigated. 2. Twenty min of ischaemia was induced by four-vessel occlusion in Wistar rats, extracellular compounds were sampled by use of microdialysis and EEG was recorded by a tungsten electrode attached to the dialysis probe. 3. Propentofylline (10 mg kg-1 i.p.) did not influence the basal levels of any of the compounds in the hippocampal dialysates. 4. The EEG became isoelectric within 20 s after induction of ischaemia. 5. Extracellular adenosine, inosine, hypoxanthine, aspartate and glutamate increased several fold during ischaemia and remained elevated during early reflow. Within 2 h of reperfusion the concentration of all compounds was normalized. Xanthine increased upon reperfusion and remained elevated after 2 h. 6. Propentofylline (10 mg kg-1 i.p.) administered 15 min before ischaemia significantly enhanced the ischaemia-evoked increase of adenosine but attenuated the increases of the other purine catabolites and of glutamate. 7. In separate in vitro experiments, propentofylline did not inhibit adenosine deaminase activity. 8. The present data show that propentofylline enhances extracellular adenosine and lowers extracellular glutamate in vivo during ischaemia. These findings may be important in relation to the neuroprotective properties of propentofylline.     

A study of mixing conditions during nitric oxide administration using simultaneous fast response chemiluminescence and capnography

We have evaluated the mixing properties of nitric oxide in inspired gases for five different administration techniques. Nitric oxide and carbon dioxide were delivered to the ventilator system before the ventilator or after the ventilator as a continuous flow, either directly into the inspiratory limb or into a mixing chamber positioned in the inspiratory limb. Both gases were delivered as above but synchronized with inspiration. Mixing conditions were evaluated using fast response chemiluminescence for nitric oxide and capnography for carbon dioxide analysis. Administration of nitric oxide and carbon dioxide directly into the inspiratory limb as a continuous flow or with a magnetic valve-controlled synchronized flow resulted in peak concentrations of 236% and 220%, respectively, of expected values. The use of a mixing chamber reduced these values to 104% and 102%, respectively. Administration of nitric oxide as a continuous flow into the tubing of an intermittent flow ventilator resulted in highly fluctuating inspiratory peak concentrations, which could be avoided with a mixing chamber.      

Perfluorochemicals as US contrast agents for tumor imaging and hepatosplenography: preliminary clinical results

In animals, perfluorochemicals (PFCs) are effective ultrasound (US) contrast agents that produce hepatic, splenic, and tumor enhancement. The use of Fluosol-DA 20%, an emulsion of perfluorodecalin and perfluorotripropylamine, was studied in nine non-critically ill patients with cancer who had liver lesions. US studies without Fluosol were compared with studies obtained 24, 48, and 72 hours after Fluosol infusion. Vital signs and extensive laboratory analyses are performed before and after Fluosol infusion. Liver metastases from colonic, pancreatic, and gastric carcinoma exhibited rim or diffuse enhancement after a Fluosol dose of 1.6 g/kg or greater. Fluosol produced echogenic enhancement of the liver and spleen relative to kidney at a dose of 2.4 g/kg, allowing the detection of nonenhancing lesions. In addition, Fluosol at a dose of 1.6 g/kg or greater allowed detection of lesions not seen before contrast medium was administered in three of the seven patients studied. There was a mild increase in the level of serum glutamic oxaloacetic transaminase in two patients, one given 2.4 and the other 3.2 g/kg of Fluosol. Mild and transient allergic reactions without change in vital signs were experienced by two patients.     

Classical and anaplastic seminoma: difference in survival

Classical and anaplastic seminoma are traditionally treated with radiation therapy and are said to have the same prognosis. A retrospective study was undertaken of 90 seminoma patients treated with radiation therapy between 1961 and 1985. The classical group consisted of 71 patients of whom 50 had stage I and 21 had stage II disease. The anaplastic group consisted of 19 patients of whom ten had stage I and nine had stage II disease. The median follow-up time was 64 months for the entire group. The 10-year relapse-free survival rate for the classical group was 94% and for the anaplastic group was 70% (P less than .05). For patients with classical stage I disease, the relapse-free actuarial survival rate was 98%; for patients with anaplastic stage I disease, it was 64% (P less than .02). For the classical stage II disease group, the relapse-free actuarial survival rate was 84% and for the anaplastic stage II disease group, 75% (P less than .70). Four patients in the classical group (6%) had relapses; of these, one patient had local recurrence of tumor, and three had distant metastases. In the anaplastic group, four patients (21%) had relapses; two patients had local recurrence of tumor, and two had distant metastases. Therefore the data suggest a difference in survival and relapse rates between classical and anaplastic seminoma.     

Optimal processing of Ektaspeed dental film

Three rapid and two standard developing solutions have been tested. A jaw specimen and an aluminium step wedge were exposed on Kodak Ektaspeed film with a 60 kVp dental x-ray machine. The films were developed during varying times at 21 degrees C under controlled conditions. The image quality was tested with a densitometer as well as visually. The characteristic density curves were constructed and the relative speed, average density, fog and contrast were calculated for each test film. The time at which the contrast specified by the film manufacturer was reached, and beyond which the speed and contrast increased only marginally was regarded as the optimal developing time. With longer developing times no increase in image quality could be perceived visual by three trained observers. The optimal developing time at room temperature 21 degrees C, for the different solutions were found to be Kodak Dental 1:1 1.5 minutes Elfwing Rapid 1:3 1.0 minutes Scanfors Dental 1:2 1.5 minutes Kodak Dental 1:3 3.0 minutes Gevaert G 150 1:5 3.0 minutes The characteristic curves were identical for all developing solutions at the times recommended above and the total fog was below 0.20. However, the image quality was maintained and only an insignificant increase of fog was found even when those times were doubled.     

Stimulation of the T-cell receptors CD3 and CD2 with OKT3 and OKT11 antibodies activates a common pertussis toxin-insensitive G-protein

The association of G-proteins with the T-cell-specific receptor structures CD3 and CD2 was investigated. High-affinity GTPase activity in membrane preparations of the human leukemic T-cell line Jurkat could be induced by the monoclonal antibodies OKT3 (anti-CD3) and OKT11 (anti-CD2). When combining maximally active concentrations of OKT3 and OKT11, no additive effect was seen on GTPase activity. In mutant Jurkat cells lacking the CD3 complex but with an intact CD2 receptor, neither OKT3 nor OKT11 could stimulate GTPase activity. Activation of CD3 and CD2 by monoclonal antibodies also stimulated phospholipase C activity as measured by breakdown of membrane phosphoinositides in wild-type but not in mutant Jurkat cells. Neither GTPase nor phospholipase C activation was sensitive to pretreatment with doses of pertussis toxin (PTX) that caused ADP ribosylation of a sensitive G-protein. Our data show that the CD3 complex and the CD2 receptor may activate a common PTX-insensitive G-protein. The CD2 receptor appears to stimulate the G-protein by interacting with the CD3 complex. The data are compatible with, but do not prove, that this G-protein is involved in the activation of phospholipase C by the two receptors.     

Localization of several G-protein subunits to the apical and basolateral membranes of cortical tubular cells from the rat kidney.

Dopamine was shown to affect Na+,K(+)-ATPase activity in basolateral membranes of the rat kidney via a pertussis toxin dependent mechanism. In order to examine if some form of pertussis toxin sensitive G-protein is present exclusively in the basolateral membrane of the rat renal cortex we examined the G-protein composition of both apical and basolateral membrane vesicles. Western blots showed an essentially uniform distribution of G alpha total, G alpha S and G beta over the two membranes. Go could not be detected with western blot technique in the vesicle preparations. By contrast, the distribution of ADP-ribosylation with the bacterial toxins pertussis toxin and cholera toxin depended on the amount of detergent in the assay and perhaps other factors, and thus could not be used to evaluate the relative amounts of G-protein subunits. Thus, in contrast to the situation in cultured renal cells, unequal distribution of receptor and G-protein substrates is apparently not paralleled by an unequal distribution of the detected forms of G-proteins under physiological conditions.     

Effects of mono- and divalent ions on the binding of the adenosine analogue CGS 21680 to adenosine A2 receptors in rat striatum.

The effect of monovalent and divalent cations on equilibrium binding of the adenosine A2-selective agonist ligand CGS 21680 (2-[p-(2-carbonylethyl)phenylethylamino]-5'-N-ethylcarboxami doadenosine) to membranes prepared from rat striatum was examined. Competition experiments with cyclohexyladenosine, 2-chloroadenosine, N-ethylcarboxamidoadenosine and CGS 21680 suggest that at 2 nM [3H]CGS 21680 binds to a single site with the pharmacology of an A2a receptor. Magnesium and calcium ions caused a concentration-dependent increase in binding that reached about 10-fold at 100 mM. Manganese ions had a biphasic effect on binding with a maximal increase at 5 mM. Lithium, sodium and potassium ions all caused a concentration-dependent decrease of binding. Sodium was most potent, potassium least. At 200 mM ion concentration, the inhibition of binding was 88% by sodium, 47% by lithium and 29% by potassium ions. The effect of sodium chloride was the same as that of sodium acetate. The effect of sodium ions was essentially similar to that of Gpp(NH)p. However, sodium ions produced a larger effect than even maximally effective concentrations of Gpp(NH)p. The maximal inhibition by Gpp(NH)p was about 55% at 2 nM radioligand concentration irrespective of the magnesium concentration. The maximal effect of sodium ions was reduced by increasing concentrations of magnesium ions. Increasing magnesium ion concentration from 1 to 100 mM increased the half-maximally effective concentration of Gpp(NH)p almost 10-fold and that of sodium ions less than 2-fold. Furthermore, sodium ions and Gpp(NH)p had additive effects. The binding of an agonist to striatal A2a receptors shows an unusually large dependence on both divalent and monovalent cations that can only partly be explained by a change in the coupling to Gs proteins.