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The ventral mesencephalon, containing the developing dopaminergic neurons of the substantia nigra-ventral tegmental region, was obtained from aborted human fetuses of 9-19 weeks of gestation. The tissue was grafted into the striatum of rats previously subjected to a 6-hydroxydopamine lesion of the mesostriatal dopamine pathway. The graft recipients were immunosuppressed by daily injections of Cyclosporin A. Amphetamine-induced motor asymmetry was reduced, and finally totally reversed, only in rats receiving grafts from the 9-week old fetal donor. The fluorescence microscopic analysis revealed large numbers of surviving dopamine neurons, and extensive fiber outgrowth into the host striatum, in these rats. By contrast, rats receiving grafts from 11-19 week old donors had at most only few surviving dopamine neurons. These results indicate that human fetal mesencephalic tissue may be an efficient source of dopamine neurons for functional intracerebral grafting in patients with Parkinson's disease.

SummaryTranexamic acid (AMCA) is an inhibitor of fibrinolysis used to treat fibrinolytic bleeding (e.g., menorrhagia and gastro-intestinal haemorrhage), and to prevent bleeding at surgery, in cases of abruptio placentae and general haemorrhage. As AMCA stabilises preformed clots and prolongs their dissolution, it has been debated whether treatment with AMCA might predispose to thrombosis by depressing the fibrinolytic system. Pregnant women constitute a group with low fibrinolytic capacity and an increased frequency of thrombosis further increased after Caesarean section, and are thus more likely to be susceptible to antifibrinolytic therapy. We therefore carried out a retrospective analysis of the case records of 2,102 patients with various bleeding disorders during pregnancy. Of the 256 patients treated with AMCA (mean duration of treatment, 46 days), 169 were delivered by Caesarean section. Of the remaining 1,846 patients (i.e., controls), 443 were delivered by Caesarean section. The relationship between the use of AMCA and the occurrence of thrombo-embolism was calculated with 95% confidence limits.Of the AMCA treated group (n = 256), two patients – one of whom belonged to the Caesarean section subgroup (n = 168) – had pulmonary embolism. Of the controls (n = 1,846), three patients had deep vein thrombosis and one had pulmonary embolism, all four cases belonging to the Caesarean section subgroup (n = 443). Thus, the findings in this high risk group of women with complicated pregnancies, frequently entailing delivery by Caesarean section, provided no evidence of any thrombogenic effect of AMCA.

Highly purified plasminogen-activator inhibitors of type 1 (PAI-1) and type 2 (PA1-2), low-M, form, were compared with respect to their kinetics of inhibition of tissue-type (t-PA) and urokinase-type plasminogen activator (u-PA). The time course of inhibition of plasminogen activator was studied under second-order or pseudo-first-order conditions. Residual enzyme activity was measured by the initial rate of hydrolysis of a chromogenic t-PA or u-PA substrate or by an immunosorbent assay for t-PA activity. PAI-1 rapidly reacted with single-chain t-PA as well as with two-chain forms of t-PA and u-PA. The second-order rate constant k for inhibition of single-chain t-PA (5.5 x lo6 M-' s-') was about three times lower than k for inhibition of the twochain activators. PAI-2 reacted slowly with single-chain t-PA, k = 4.6 x lo3 M-' s -'. The association rate was 26 times higher with two-chain t-PA and 435 times higher with two-chain u-PA. The k values for inhibition of single-chain t-PA, two-chain t-PA and two-chain u-PA were respectively, 1200, 150 and 8.5 times higher with PAI-1 than with PAI-2. The removal of the epidermal growth factor domain and the kringle domain from twochain u-PA did not affect the kinetics of inhibition of the enzyme, suggesting that the C-terminal proteinase part of u-PA (B chain) is responsible for both the primary and the secondary interactions with PAI-1 and PAI-2. The k values for inhibition of single-chain t-PA and endogenous t-PA in plasma by PAI-1 or PA1-2 were identical indicating that t-PA in blood consists mainly in its single-chain form.Two different plasminogen activators: the tissuetype, t-PA (Mr = 70000), and the urokinase-type, u-PA

In stroke patients, high TPA antigen concentrations may indicate an activation of the fibrinolytic system or may be due to a delayed clearance of TPA complexed with inhibitors. High PAI-1 antigen concentrations in patients with cerebral infarction represent increased fibrinolytic inhibition. The findings in this longitudinal study suggest that TPA and PAI-1 antigen concentrations both differ little between the acute and convalescent phases after stroke.

Gingival inflammatory symptoms are aggravated during pregnancy. In vitro studies suggest a hormonal influence on the plasminogen activator inhibitor type 2 (PAI-2), and a disturbed balance of the fibrinolytic system could help to explain pregnancy gingivitis. Gingival crevicular fluid (GCF) was sampled in 14 women in pregnant and post-pregnant states. The gingival condition was assessed by the gingival index of Løe & Silness (GI) and the amount of bacterial plaque by the plaque index of Silness & Løe (PI). The ratio of sites with gingivitis to sites with bacterial plaque was calculated (G/P-ratio). Antigen levels of tissue plasminogen activator (t-PA), urokinase-type plasminogen activator (u-PA), plasminogen activator inhibitors type 1 (PAI-1) and PAI-2 in GCF were determined with ELISAs and 17 beta-oestradiol and progesterone in serum with radioimmunoassays. For each individual the differences (delta) in hormone levels and PAs and PAIs between pregnancy and post-pregnancy were calculated. Based on differences in G/P-ratio between pregnancy and post-pregnancy, subgrouping was done into a high-reacting and a low-reacting group. For the total group, the mean G/P-ratio was 2.0 during and 1.2 after pregnancy (p = 0.064). A statistically significant correlation between delta progesterone and delta PAI-2 was noted: the higher delta progesterone, the lower delta PAI-2. No other significant correlations between hormone levels and components of the fibrinolytic system were found. For the total group of women, the concentrations of PAI-2, PAI-1 and t-PA were significantly higher during than after pregnancy. The individuals in the high-reacting group, however, showed a lower or unchanged production of PAI-2 during pregnancy, while those in the low-reacting group showed a greatly increased production. The lower inhibitory capacity in terms of a low production of PAI-2 during pregnancy in women with a higher inflammatory reaction indicates that the components of the fibrinolytic system may be involved in the development of pregnancy gingivitis and implies that PAI-2 serves as an inhibitor of importance for tissue proteolysis. The present finding contributes to the explanation of pregnancy gingivitis.