Synergism between tissue-type plasminogen activator and a genetically engineered variant lacking the finger domain, the growth factor domain and the first kringle domain.

A modified variant of human tissue-type plasminogen activator (t-PA) lacking the finger domain (F), the growth factor domain (G) and the first kringle domain (K1), has an extended plasma half-life in vivo, compared to that of t-PA. When the variant (denoted K2P) was tested in vitro for its ability to lyse human plasma clots we found that the activity was characterized by a time lag phase and a sigmoidal dose-response curve. However, an attenuation of the lag phase in vitro was observed both when K2P was mixed with t-PA in a w/w ratio of 4:1 and when K2P was allowed to lyse a clot that had been pre-exposed to t-PA i.e. submitted to a limited plasmic digestion. Dosis that in vitro caused 50% lysis within 6 h were calculated from individual dose-response curves and were for K2P, t-PA and K2P/t-PA (4:1 w/w) 540 ng/ml, 360 ng/ml and 310 ng/ml, respectively. These results indicated a synergistic effect between K2P and t-PA. However, the data from individual dose-response curves showed that the effect of the K2P/t-PA mixture never was better than that of t-PA alone, and the synergistic effect in vitro is therefore considered to be of limited use. The thrombolytic activity in vivo was evaluated in a rabbit jugular vein thrombus model. Despite the lag phase observed in vitro, K2P was approximately 3 times as effective as t-PA in vivo (bolus injection). The thrombolytic effect of K2P was further potentiated when it was administered together with a small amount of t-PA (4:1 w/w).(ABSTRACT TRUNCATED AT 250 WORDS)     

A two-stage study on multiple sclerosis susceptibility and chromosome 2q33

We have performed a two-stage study to analyse the association of polymorphism on chromosome 2q33 with multiple sclerosis (MS). In all, 17 markers were analysed in stage-1 in 134 Finnish MS families and the observed associations were tested in stage-2 in 186 MS families. We did not find previously reported allelic or haplotype associations with CTLA4. We obtained a weak signal of two distinct predisposing genes, one proximal the other distal of CTLA4. The putative proximal gene was associated with the marker rs3977 in families lacking HLA-DR2 (P=0.02 and 0.02) and the other distal gene was associated with D2S1271 in families from a high-risk region in western Finland (P=0.02 and 0.01). Based on the >3 cM distance and the lack of linkage disequilibrium between these loci, we conclude that the two association signals are independent. Our results provide preliminary evidence for two distinct MS susceptibility genes on 2q33 outside of CTLA4.     

Some storage characteristics of platelet concentrates contaminated with pseudomonas aeruginosa

The present work investigates the effects of contamination with Pseudomonas aeruginosa on some properties of platelet concentrates, i.e. the ability to transmit light, swirling and the degree of platelet activation and cell lysis. 20 pairs of platelet concentrates were studied over a 7 day period. On day 1, one of the concentrates was inoculated with Pseudomonas aeruginosa, while the other served as an identical non-contaminated control. In the contaminated concentrates, swirling and release of platelet factor 4 and lactate dehydrogenase were analysed on day 1, day 2 and day 3; bacterial counts were performed on day 2 and day 3, and on day 7 all these variables were determined in both concentrates. After the 7 day storage period, bacterial growth was found in 13/16 of the contaminated platelet concentrates; all these preparations displayed transmission changes and at least one deviating biochemical parameter. On day 3 all contaminated concentrates had unimpaired swirling, 15/20 had bacterial growth and 10/20 light transmission changes. The study demonstrates that light transmission monitoring on day 3 offers significant advantage (p < 0.05) compared to the visual estimation of swirling. The results also show that the optical method often fails to identify contaminated concentrates during early storage.     

Serological response of multiple sclerosis patients and controls to 6/94-parainfluenza virus

Summary The serological responses of 195 multiple sclerosis (MS) patients and 251 controls were tested against 6/94-parainfluenza virus, which was previously isolated from brain tissue of two patients with MS. The hemagglutination-inhibition titers of 1:128 were found more frequently in MS patients (21.5%) than in controls (14.0%). However, the geometric mean titers did not differ between these two groups. The present study concludes that a causal relationship of 6/94-virus to MS, based on a specific immune response, is improbable, although it does not exclude the possibility of a pathogenetic significance of the agent in the cases from which the autopsy material was derived.Supported by Deutsche Forschungsgemeinschaft (Schwerpunkt Ätiologie und Pathogenese der Multiplen Sklerose und verwandter Erkrankungen)     

8-hydroxy-2-(di-n-propylamino)tetralin, 8-OH-DPAT,a potent and selective simplified ergot congener with central 5-HT-receptor stimulating activity

Summary It was demonstrated that the simplified ergot congener 8-hydroxy-2-(di-n-propylamino)tetralin, 8-OH-DPAT, is able to elicit pronounced biochemical and behavioural alterations indicative of central serotoninomimetic activity. Since these effects are resistant to prior monoamine depletion and/or synthesis inhibition by means of reserpine and-propyldopacetamide (H22/54), respectively, they are most likely to be attributable to direct serotonin-receptor agonism by 8-OH-DPAT. With regard to central 5-HT neurotransmission the effects of 8-OH-DPAT-increased 5-HT levels, decreased 5-HIAA levels, 5-HT-synthesis rate and 5-HT utilization and inhibited 5-HT neuronal firing-are virtually identical, and comparable in potency, to those reported to result from the administration of lisuride or LSD. In contrast, however, to lisuride and LSD (included for comparative purposes in this study) as well as to several differently N-substituted, 5,6-dihydroxy, 6,7-dihydroxy and 5-, 6- and 7-monohydroxy 2-aminotetralins, 8-OH-DPAT lacks appreciable effects on central catecholamine receptors. The compound may thus be regarded the most potent, selective centrally acting 5-HT agonist described to date. accordance with this it was shown that the full-blown 5-HT-like behaviour syndrome induced by 8-OH-DPAT cannot be antagonized by reserpin phenoxybenzamine, propranolol and haloperidol. In addition, of the truputative 5-HT-receptor blockers cyproheptadine, methergoline and methrothepin only the latter was able to counteract the 8-OH-DPAT-induce syndrome. The results are discussed in relation to the recent subclassification of central 5-HT receptor sites.A comparison between the chemical structures and biological activities for different fragments of the ergot nucleus was also made. The data suggest, in that while the role of the A ring in the ergot structure for dopaminer activity at present is unclear, this ring may be important for the 5-HT-receptor activity like in e.g. lisuride and LSD.Moreover, based on the present results and literature reports, it is speculated that a selective 5-HT-receptor agonist such as 8-OH-DPAT would be liable to induce hallucinations in man.Presented in part at the 19th ACNP meeting, San Juan, December 15–19,1980. [Psychoph. Bull.17, 180–183 (1981).]     

EFFECT OF TRANSCUTANEOUS NERVE STIMULATION ON MICROCIRCULATION IN INTACT SKIN AND BLISTER WOUNDS IN HEALTHY VOLUNTEERS

Healthy non-smoking volunteers participated in two experimental studies in which the circulatory changes induced by transcutaneous nerve stimulation (TENS) were quantified by two different methods. In experimental series 1 (intact skin), nine volunteers were given TENS on the left lower leg for 60 minutes on three occasions at different frequencies each time (2 Hz, 100 Hz, and sham). Changes in blood flow were assessed by laser Doppler imaging technique every five minutes. The mean blood flow increased by 40% during low frequency TENS and by 12% during high frequency TENS. There was no change in mean blood flow during sham stimulation. In experimental series 2 (blister wound), the circulatory changes induced by TENS were studied by intravital video microscopy and computerised image analysis in standard blister wounds on the lower leg. The microcirculatory blood flow, measured as red blood cell velocity (RBC-V) in 5-14 individual capillaries in each wound, was assessed before and during 45 minutes of TENS (2 Hz and 100 Hz). Mean RBC-V increased by 23% during low frequency TENS (n = 6) and by 17% during high frequency TENS (n = 8). The results show that: laser Doppler imaging and intravital video microscopy techniques can be used to study events at the microcirculatory level; the blister wound is an interesting new standard wound for use in clinical studies; and TENS stimulates the peripheral cirulation.     

Role of histamine release in nonspecific vasodilatation during anodal and cathodal iontophoresis

Nonspecific vasodilatation during iontophoresis is an important confounding factor in experimental pharmacology. In this investigation, we studied the involvement of sensory nerves and histamine-related reactions in causing nonspecific vasodilatation in a model of anodal and cathodal iontophoresis of sodium chloride. Firstly, we applied a mixture of local anesthetic (EMLA) cream to confirm its suppressive effect on nonspecific vasodilatation and to measure its efficacy in three different dosages (duration: 1, 2, and 3 h). We then investigated the role of histamine in nonspecific vasodilatation by giving an oral antihistamine drug (cetirizine) to subjects who had and had not been given EMLA. We found substantial suppression of the nonspecific vasodilatation in all EMLA-treated groups (all dosages) compared with untreated controls (with suppression rates of 60-65%). Dosage had no significant effect. A further suppression of nonspecific vasodilatation was seen after oral cetirizine during anodal and cathodal iontophoresis in both EMLA-treated and untreated groups. The antihistamine effect was most pronounced during anodal iontophoresis. These results suggest a histaminergic increase in perfusion that may be independent of neurogenic mechanisms and depend on polarity (anode or cathode). Local nerve blocks (EMLA) together with cetirizine may therefore be used to reduce nonspecific vasodilatation in both anodal and cathodal iontophoresis.