NeuMonD: a tool for the development of new indicators of anaesthetic effect.

Electroencephalogram (EEG) signals and auditory evoked potentials (AEPs) have been suggested as a measure of depth of anaesthesia, because they reflect activity of the main target organ of anaesthesia, the brain. The online signal processing module NeuMonD is part of a PC-based development platform for monitoring "depth" of anaesthesia using EEG and AEP data. NeuMonD allows collection of signals from different clinical monitors, and calculation and simultaneous visualisation of several potentially useful parameters indicating "depth" of anaesthesia using different signal processing methods. The main advantage of NeuMonD is the possibility of early evaluation of the performance of parameters or indicators by the anaesthetist in the clinical environment which may accelerate the process of developing new, multiparametric indicators of anaesthetic "depth".     

THE EFFECT OF PHENOBARBITONE ANAESTHESIA UPON SOME ORGANIC PHOSPHATES, GLYCOLYTIC METABOLITES AND CITRIC ACID CYCLE-ASSOCIATED INTERMEDIATES OF THE RAT BRAIN

In order to study the effect of phenobarbitone anaesthesia upon the energy metabolism of the brain, organic phosphates, glycolytic metabolites and citric acid cycle intermediates were measured in rats anaesthetized with 175-200 mg/kg of phenobarbitone, and the results were compared to those obtained in rats anaesthetized with halo-thane or with nitrous oxide. An attempt was made to separate the effects of the phenobarbitone anaesthesia from those caused by the accompanying intracellular alkalosis by exposing one group of animals to hypercapnia of such a degree that normalization of the intracellular pH was achieved. Phenobarbitone anaesthesia did not alter the tissue concentrations of ATP, ADP or AMP, but led to a moderate increase in the phosphocreatine concentration. However, since this increase was reversed in the hypercapnic group it is concluded that it may be due partly to a pH-dependent shift in the creatine phosphokinase equilibrium. There was a decrease in the tissue concentrations of all measured substrates from pyruvate and onwards. The results indicate that phenobarbitone leads to a primary inhibition of glycolysis, which cannot be related to detectable changes in ATP, ADP or AMP. The resulting lowering of the tissue concentrations of a number of metabolic acids may be part of the explanation why barbiturate anaesthesia is associated with an intracellular alkalosis.     

Plasminogen activator in prostatic tumors of Nb rats

Using a fluorometric assay, nonspecific proteolytic activity and plasminogen activator were measured in transplantable tumors of the dorsal prostate of Nb rats. Nonspecific proteolytic activity in prostatic tumors did not differ significantly from that measured in normal dorsal prostate, whereas plasminogen activator activity, undetectable in the latter tissue, was readily measurable in the tumors. Furthermore, plasminogen activator in prostatic tumors characterized by hormone-insensitive growth was 8-fold higher than in tumors characterized by androgen-stimulated growth. In both types of tumors, the plasminogen activator activity per mg protein was highest in the lysosomal fractions. The result indicate that plasminogen activator may be a useful marker for discriminating between androgen-stimulated and autonomous prostatic tumors.     

Effects of stopping smoking for 48 hours on oxygen availability from the blood: a study on pregnant women.

The effects of stopping smoking for 48 hours on factors governing the availability of oxygen from the blood--that is, carboxyhaemoglobin (COHb), haemoglobin-oxygen (HbO2) affinity, and haemoglobin concentration--were measured in women in the last trimester of pregnancy. Three groups were studied: smokers, smokers who stopped smoking for 48 hours, and non-smokers. The 22 smokers had higher initial COHb values and greater HbO2 affinity than the 10 non-smokers, but their total haemoglobin concentrations were also higher, so that their oxygen availability was not significantly reduced. In the 11 smokers who stopped the reduction in COHb and decrease in HbO2 affinity led to a significant increase of 8% in "available oxygen" in 48 hours. Since even small improvements in oxygen delivery to the tissues may confer critical benefit to the fetus, particularly during labour or when exposed to general anaesthesia, smoking should be discouraged for 48 hours before elective deliveries. The same consideration might reasonably be applied to patients undergoing general anaesthesia for all elective operations.     

Effect of hypothermia on radiosensitization

Hypothermia reduces metabolism and oxygen utilization by tissues. If the blood supply to a solid tumour can be maintained at a sufficient level, the hypoxic fraction of tumour cells may be reduced and radiosensitivity increased. This may be achieved if hyperbaric oxygen is used in combination with the hypothermia. The blood supply and oxygen tension have been measured in C3H mouse mammary tumours under hypothermia and hyperbaric oxygen, and the enhancement of radiosensitivity by hyperbaric oxygen has been estimated in mice irradiated at different temperatures with and without anaesthesia. Measurement of xenon-133 clearance showed that the blood supply of a tumour tended to increase when anaesthetized mice became hypothermic. Oxygen cathode data showed that the oxygen tension tended to be relatively higher in tumours and lower in subcutaneous tissue when mice exposed to hyperbaric oxygen became hypothermic under anaesthesia. Hyperbaric oxygen enhanced the radiation response of the tumour in terms of an increase in regrowth delay by a factor of 1.7 when the mice had been anaesthetized, whether or not they became hypothermic. A lower factor of 1.4 was obtained without anaesthesia although induced hypothermia increased the response to a small extent. We conclude that anaesthesia and hypothermia affect oxygen metabolism in tumours by different mechanisms.     

Urine Output and Fluid Therapy During Anaesthesia and Surgery

To try to determine whether fluid therapy during surgery should be on a large or a small scale 23 patients and six control subjects were studied. The control subjects were fasted and transfused with 2 litres of Ringer-lactate solution in one hour, the volume of urine output being measured at intervals for four hours. The patients were transfused similarly under varying conditions of anaesthesia and surgery. The characteristic urine output during abdominal hysterectomy followed a low, irregular pattern, and this occurred whether or not substantial amounts of fluid were transfused. In two patients anaesthesia and minimal trauma were associated with oliguria. An established diuresis was altered by anaesthesia and inhibited by surgery. These results indicate that excess Ringer-lactate solution administered during surgery may not be excreted and that overtransfusion could easily occur.     

Possibility of Application of Extracellular Protease of the Micromycetе <Emphasis Type="Italic">Aspergillus ochraceus</Emphasis> VKM F-4104D for Determination of the Protein C Content in Human Blood Plasma

The protein C activator activity, determined in normal plasma by using A. ochraceus protease is comparable with the activity of a commercial protease analogue from the South American copperhead venom (Protac®). As in the case of Protac®, the A. ochraceus protease can be used for protein C determination in plasma with its reduced content. Comparison of the activator protein C activity of A. ochraceus protease and the commercial analogue showed some excess of the activator activity of the fungal preparation, which may be a promising substitute for the snake activator in diagnostical kits for determining the protein C content in clinical laboratories.     

Regulation of extracellular plasminogen activator by human fibroblasts. The role of protease nexin

When the plasminogen activator urokinase was radioiodinated and incubated at 40 ng/ml in medium conditioned by human foreskin (HF) cells, within 30 min over 80% of the added plasminogen activator was complexed to cell-released protease nexin (PN). The urokinase complexed to PN had little if any activity. Incubation of purified PN with urokinase confirmed that PN is an inhibitor of this plasminogen activator. However, a widely used plasminogen-dependent fibrinolysis assay for plasminogen activator indicated that abundant endogenous plasminogen activator activity co-existed with PN in HF cell-conditioned medium. The source of this activity was electrophoretically and immunologically indistinguishable from urokinase. Furthermore, gel exclusion chromatography showed that about 90% of the urokinase antigen detected in conditioned medium had a molecular weight similar to that of free active urokinase. These paradoxical findings are resolved by evidence that this "PN-resistant urokinase-like" plasminogen activator is actually urokinase proenzyme that is activated by plasmin or conditions in the fibrinolysis assay for plasminogen activator. It is shown that the activated form of HF cell plasminogen activator is sensitive to inhibition by PN. PN may thus be an important component in the cellular regulation of endogenous plasminogen activator activity.     

Activation ofClostridium perfringens cytotoxic enterotoxin(s) in vivo and in vitro: Role in triggers for sudden infant death

The action ofClostridium perfringens cytotoxic enterotoxins may be activated/exacerbated both in vivo and in vitro by the addition of an activator molecule present in a brush border membrane fraction isolated from young rabbits. Increased concentrations of the activator could be induced by immunologically stimulating rabbits with Ribi adjuvant. Comparative studies suggested that the activator was interferon-gamma (IFN-). In vitro IFN- sensitized cell lines apparently by enhancement of cell permeability, which allowed a more rapid uptake of the toxins, resulting in cell death at lower toxin concentrations. Viral and/or bacterial infections are inducers of IFNs. We propose that some immunologically immature infants are predisposed to infection. In the weeks prior to death, these infants may suffer from an infection that induces the synthesis of IFNs, sensitizing the infant to a more virulent infection and possible sudden death.Florida Agricultural Experiment Station Journal Series No. R-02380     

Orexin A Inhibits Propofol-Induced Neurite Retraction by a Phospholipase D/Protein Kinase Cε-Dependent Mechanism in Neurons

Background

The intravenous anaesthetic propofol retracts neurites and reverses the transport of vesicles in rat cortical neurons. Orexin A (OA) is an endogenous neuropeptide regulating wakefulness and may counterbalance anaesthesia. We aim to investigate if OA interacts with anaesthetics by inhibition of the propofol-induced neurite retraction.

Methods

In primary cortical cell cultures from newborn rats’ brains, live cell light microscopy was used to measure neurite retraction after propofol (2 µM) treatment with or without OA (10 nM) application. The intracellular signalling involved was tested using a protein kinase C (PKC) activator [phorbol 12-myristate 13-acetate (PMA)] and inhibitors of Rho-kinase (HA-1077), phospholipase D (PLD) [5-fluoro-2-indolyl des-chlorohalopemide (FIPI)], PKC (staurosporine), and a PKCε translocation inhibitor peptide. Changes in PKCε Ser⁷²⁹ phosphorylation were detected with Western blot.

Results

The neurite retraction induced by propofol is blocked by Rho-kinase and PMA. OA blocks neurite retraction induced by propofol, and this inhibitory effect could be prevented by FIPI, staurosporine and PKCε translocation inhibitor peptide. OA increases via PLD and propofol decreases PKCε Ser⁷²⁹ phosphorylation, a crucial step in the activation of PKCε.

Conclusions

Rho-kinase is essential for propofol-induced neurite retraction in cortical neuronal cells. Activation of PKC inhibits neurite retraction caused by propofol. OA blocks propofol-induced neurite retraction by a PLD/PKCε-mediated pathway, and PKCε maybe the key enzyme where the wakefulness and anaesthesia signal pathways converge.     

Effect of preoperative anaesthetic visit on anxiety.

Anxiety levels measured in patients who received preoperative reassurance about anaesthesia from a member of the hospital staff were significantly lower than those in a control group given no such support. Anxiety levels in patients who read a booklet designed to reassure about anaesthesia were less significantly reduced. Owing to the increasing work load in the operating theatre many anaesthetists can no longer afford the time to visit patients preoperatively. This study shows that either this trend should be reversed or the role of reassurer should be assumed by someone else, possibly the anaesthetic nurse. For optimal effect, the visits should be combined with use of the booklet. Unless such measures are taken, up to three million people each year may be being denied any form of reassurance before surgical treatment.     

Two different mechanisms in patients with venous thrombosis and defective fibrinolysis: low concentration of plasminogen activator or increased concentration of plasminogen activator inhibitor.

Fibrinolytic components after venous occlusion and concentrations of tissue plasminogen activator inhibitor were studied in 100 consecutive patients with confirmed recurrent deep vein thrombosis or pulmonary embolism. After 20 minutes of venous occlusion the fibrinolytic response was decreased in 33 patients, as measured both amidolytically with S-2251 and on fibrin plates. Two different mechanisms responsible for the poor fibrinolytic response could be distinguished. Twenty two of the patients in whom the response was poor released normal amounts of tissue plasminogen activator antigen, as assayed by immunoradiometric assay, but had appreciably increased concentrations of tissue plasminogen activator inhibitor. The 11 other patients in whom the response was poor had both low tissue plasminogen activator activities and low tissue plasminogen activator antigen concentrations but normal concentrations of tissue plasminogen activator inhibitor. The results show not only that defective synthesis or release of tissue plasminogen activator may be important in the pathogenesis of venous thrombosis but also that a large group of patients with thrombosis have an increased concentration of the inhibitor to tissue plasminogen activator.     

A New Anaesthetic Protocol for Adult Zebrafish (Danio rerio): Propofol Combined with Lidocaine

Background

The increasing use of zebrafish model has not been accompanied by the evolution of proper anaesthesia for this species in research. The most used anaesthetic in fishes, MS222, may induce aversion, reduction of heart rate, and consequently high mortality, especially during long exposures. Therefore, we aim to explore new anaesthetic protocols to be used in zebrafish by studying the quality of anaesthesia and recovery induced by different concentrations of propofol alone and in combination with different concentrations of lidocaine.

Material and Methods

In experiment A, eighty-three AB zebrafish were randomly assigned to 7 different groups: control, 2.5 (2.5P), 5 (5P) or 7.5 μg/ml (7.5P) of propofol; and 2.5 μg/ml of propofol combined with 50, (P/50L), 100 (P/100L) or 150 μg/ml (P/150L) of lidocaine. Zebrafish were placed in an anaesthetic water bath and time to lose the equilibrium, reflex to touch, reflex to a tail pinch, and respiratory rate were measured. Time to gain equilibrium was also assessed in a clean tank. Five and 24 hours after anaesthesia recovery, zebrafish were evaluated concerning activity and reactivity. Afterwards, in a second phase of experiments (experiment B), the best protocol of the experiment A was compared with a new group of 8 fishes treated with 100 mg/L of MS222 (100M).

Results

In experiment A, only different concentrations of propofol/lidocaine combination induced full anaesthesia in all animals. Thus only these groups were compared with a standard dose of MS222 in experiment B. Propofol/lidocaine induced a quicker loss of equilibrium, and loss of response to light and painful stimuli compared with MS222. However zebrafish treated with MS222 recovered quickly than the ones treated with propofol/lidocaine.

Conclusion

In conclusion, propofol/lidocaine combination and MS222 have advantages in different situations. MS222 is ideal for minor procedures when a quick recovery is important, while propofol/lidocaine is best to induce a quick and complete anaesthesia.     

Modulation of plasminogen activator production by interleukin 1: differential responses of fibroblasts derived from human skin and rheumatoid and non-rheumatoid synovium

Rheumatoid synovial fibroblasts were treated with purified porcine interleukin 1 alpha and recombinant human interleukin 1B, and the production of secreted and cell-associated plasminogen activator activity was measured. No stimulation of plasminogen activator activity was seen in response to either preparation of interleukin 1, and in more than half of the cell cultures interleukin 1 caused a significant decrease in the secreted levels of PA activity. Increased levels of prostaglandin E were produced in the same experiments, indicating that the cells were responsive to the interleukin 1 preparations. Both retinoic acid and unfractionated monocyte conditioned medium were able to stimulate the production of PA activity by the rheumatoid synovial fibroblast cultures. The rheumatoid synovial fibroblasts produced two species of plasminogen activator as indicated by SDS polyacrylamide gel electrophoresis, with apparent Mr of approx. 50,000 and 100,000. The Mr = 50,000 species co-migrates with urokinase-type plasminogen activator. No species is produced which co-migrates with tissue type plasminogen activator. Studies with antibodies also indicate that the activity produced is urokinase-type plasminogen activator. The Mr = 100,000 species may be an enzyme-inhibitor complex. Two non-rheumatoid synovial fibroblast cultures and two out of six human skin fibroblast cultures did produce elevated levels of plasminogen activator activity in response to recombinant human interleukin 1B. The results suggest that fibroblast populations may differ in their response to interleukin 1, in terms of production of plasminogen activator activity.     

Sufentanil and medetomidine anaesthesia in the rat and its reversal with atipamezole and butorphanol

Injectable anaesthetics are widely used to anaesthetize rats, but recovery times are often prolonged. Reversible anaesthetic regimens have the advantage that animals may be recovered quickly, thus reducing the incidence of postoperative complications such as hypothermia, and also providing a means of treating inadvertent anaesthetic overdose. This study assessed and compared the characteristics of anaesthesia induced with combinations of sufentanil and medetomidine administered as a single subcutaneous or intraperitoneal dose, and reversal with butorphanol and atipamezole. Combinations of sufentanil/medetomidine at 40 microg/150 microg and 50 microg/150 microg/kg administered subcutaneously, and 80 microg/300 microg/kg by intraperitoneal injection were found to produce surgical anaesthesia for 101+/-49, 124+/-45 and 76+/-23 min (means +/- SD) respectively. All three combinations produced marked respiratory depression 30 min after injection (< 50% of resting respiratory rate). Oxygen saturation, measured by pulse oximetry, was < 50% in all groups 30 min following drug administration. Subcutaneous administration is recommended since it resulted in a more reliable and more rapid induction of anaesthesia than intraperitoneal administration. The administration of butorphanol and atipamezole (0.2/0.5 mg/kg s.c.) resulted in a rapid (< 7 min) reversal of anaesthesia and an associated respiratory depression. The induction of anaesthesia with sufentanil/medetomidine and its reversal with a combination of atipamezole and butorphanol is an effective technique for anaesthetizing rats. However, due to the marked respiratory depression and the resulting hypoxia, we recommend that this regimen should only be used in animals which are free from respiratory disease and that oxygen should be provided during anaesthesia.     

Blood sampling from the retro-orbital plexus, the saphenous vein and the tail vein in rats: comparative effects on selected behavioural and blood variables

We compared the behaviours of rats, and measured various blood parameters, after three blood sampling techniques: orbital puncture while they were under diethyl-ether anaesthesia, blood collection by tail vein puncture under O2-N2O-halothane anaesthesia and puncture of the saphenous vein without anaesthesia. Twelve rats were subjected to the three treatments according to a Latin square design. After each treatment, the behaviour of the rats was automatically monitored using the so-called LABORAS method, which discriminates between grooming, locomotion and inactivity in rats. Based on excitation scores and urine production, it was found that induction of diethyl-ether anaesthesia combined with orbital puncture caused more distress than did the other two blood sampling techniques. The three techniques had no differential effects on the behaviours of grooming, locomotion and inactivity. Collecting 0.5 ml of blood by orbital puncture was +/-7 times faster than doing so by saphenous vein puncture and +/- 15 times faster than collecting blood by tail vein puncture while the rats were under O2-N2O-halothane anaesthesia. The levels of some haematological and plasma variables differed significantly between the three blood collection techniques. These observations may help to select the most appropriate technique of blood sampling with respect to anticipated discomfort in the animals.     

Noninvasive cardiac output and blood pressure monitoring cannot replace an invasive monitoring system in critically ill patients

Background

Sub-Tenon's anaesthetic is effective and reliable in producing both akinesia and anaesthesia for cataract surgery. Our clinical experience indicates that it is sometimes necessary when absolute akinesia is required during surgery to augment the block with 1–2 ml of local anaesthetic. Hypothesis was that after first injection some of the volume injected may spill out and before second injection the effect of hyaluronidase has taken place and second volume injectate will have desired effect.

Methods

A prospective, randomised, control trial in which patients were randomly allocated to one of two groups. In group 1, single injection of 5 ml of local anaesthetic was injected. In group 2, 3 ml of the same anaesthetic solution was injected followed by application of gentle orbital pressure for 2 minutes. A further 2 ml of the same anaesthetic solution was injected through the same conjunctival incision. Measurement of movement in four quadrants of eye was done by the surgeon at 3 and 6 minutes. Intraocular pressure, chemosis, and subconjuctival haemorrhage were also measured.

Results

Significant differences at 3 minutes between groups for overall movement, medial, superior, and lateral quadrants occurred. At 6 minutes no significant group differences emerged for the overall movement or for any of four quadrants.

Conclusion

Single injection of local anaesthesia for sub-Tenon's block with mixture of lignocaine with adrenaline, bupivacaine and hyaluronidase was found to be superior to provide akinesia of ocular muscles compared to divided dose given by two injections. No difference in groups in terms of haemorrhage, chemosis, patient's satisfaction and intraocular pressure was found.

Trial registration

Trial registration no-ISRCTN73431052     

ATF-PAI2CD融合蛋白基因在毕赤酵母中克隆、表达和鉴定

为了克隆尿激酶型纤溶酶原激活物 (uPA)的氨基末端片段与纤溶酶原激活剂抑制物 2型(PAI 2 )突变体所构成的融合蛋白基因 ,并在Pichiapastoris中表达 ,应用PCR获得了人ATF PAI2CD融合蛋白基因cDNA(简称ATF PAI2CD) ,将其克隆到酵母表达载体pPIC9K ,获得融合基因表达质粒pZWY ATF PAI2CD .该质粒转化毕赤酵母菌GS115 ,用G4 18 YPD平板筛选高拷贝转化子 ,然后用甲醇诱导表达 .工程菌用摇瓶发酵 ,表达产物ATF PAI2CD占培养液中总蛋白 5 0 %以上 .经硫酸铵沉淀、分子筛和离子交换层析纯化得到的目标表达产物纯度达 95 % .Western印迹检测具有PAI 2与uPA的免疫原性 ,经牛奶板法检测具有纤溶抑制活性 .经流式细胞仪 (FCM )检测 ,能与肿瘤细胞特异性结合 .结果表明 ,ATF PAI2CD融合蛋白成功地在毕赤酵母中表达 ,且具有抑制uPA及与肿瘤细胞表面uPAR特异性结合的双重功能 .提示该融合蛋白可能具有良好的应用前景 .     

Use of local anaesthetics and adjuncts for spinal and epidural anaesthesia and analgesia at German and Austrian University Hospitals: an online survey to assess current standard practice

Background

The present anonymous multicenter online survey was conducted to evaluate the application of regional anaesthesia techniques as well as the used local anaesthetics and adjuncts at German and Austrian university hospitals.

Methods

39 university hospitals were requested to fill in an online questionnaire, to determine the kind of regional anaesthesia and preferred drugs in urology, obstetrics and gynaecology.

Results

33 hospitals responded. No regional anaesthesia is conducted in 47% of the minor gynaecological and 44% of the urological operations; plain bupivacaine 0.5% is used in 38% and 47% respectively. In transurethral resections of the prostate and bladder no regional anaesthesia is used in 3% of the responding hospitals, whereas plain bupivacaine 0.5% is used in more than 90%. Regional anaesthesia is only used in selected major gynaecological and urological operations. On the contrary to the smaller operations, the survey revealed a large variety of used drugs and mixtures. Almost 80% prefer plain bupivacaine or ropivacaine 0.5% in spinal anaesthesia in caesarean section. Similarly to the use of drugs in major urological and gynaecological operations a wide range of drugs and adjuncts is used in epidural anaesthesia in caesarean section and spontaneous delivery.

Conclusions

Our results indicate a certain agreement in short operations in spinal anaesthesia. By contrast, a large variety concerning the anaesthesiological approach in larger operations as well as in epidural analgesia in obstetrics could be revealed, the causes of which are assumed to be primarily rooted in particular departmental structures.     

alpha Domain deletion converts streptokinase into a fibrin-dependent plasminogen activator through mechanisms akin to staphylokinase and tissue plasminogen activator

The mechanism of action of plasminogen (Pg) activators may affect their therapeutic properties in humans. Streptokinase (SK) is a robust Pg activator in physiologic fluids in the absence of fibrin. Deletion of a "catalytic switch" (SK residues 1-59), alters the conformation of the SK alpha domain and converts SKDelta59 into a fibrin-dependent Pg activator through unknown mechanisms. We show that the SK alpha domain binds avidly to the Pg kringle domains that maintain Glu-Pg in a tightly folded conformation. By virtue of deletion of SK residues 1-59, SKDelta59 loses the ability to unfold Glu-Pg during complex formation and becomes incapable of nonproteolytic active site formation. In this manner, SKDelta59 behaves more like staphylokinase than like SK; it requires plasmin to form a functional activator complex, and in this complex SKDelta59 does not protect plasmin from inhibition by alpha(2)-antiplasmin. At the same time, SKDelta59 is unlike staphylokinase or SK and is more like tissue Pg activator, because it is a poor activator of the tightly folded form of Glu-Pg in physiologic solutions. SKDelta59 can only activate Glu-Pg when it was unfolded by fibrin interactions or by Cl(-)-deficient buffers. Taken together, these studies indicate that an intact alpha domain confers on SK the ability to nonproteolytically activate Glu-Pg, to unfold and process Glu-Pg substrate in physiologic solutions, and to alter the substrate-inhibitor interactions of plasmin in the activator complex. The loss of an intact alpha domain makes SKDelta59 activate Pg through classical "fibrin-dependent mechanisms" (akin to both staphylokinase and tissue Pg activator) that include: 1) a marked preference for a fibrin-bound or unfolded Glu-Pg substrate, 2) a requirement for plasmin in the activator complex, and 3) the creation of an activator complex with plasmin that is readily inhibited by alpha(2)-antiplasmin.