Skeletal muscle ventricles with efferent valved homograft

Skeletal muscle ventricles (SMVs) were constructed from the latissimus dorsi muscle in seven beagles. Following 3 weeks of vascular delay and 6 weeks of electrical conditioning, the SMVs were connected in series with the thoracic aorta using a valved aortic homograft for the efferent limb. The SMVs were stimulated to contract synchronously during diastole. Effective aortic diastolic counterpulsation was achieved in all dogs, with an average 24.2% +/- 15.3% improvement in diastolic pressure. In two animals surviving beyond 3 months, increase in SMV function was noted over time. Appropriate aortic homograft valve function was documented by echocardiogram. Acute reversible heart failure was induced with propranolol in one dog alive after 126 days. A 61.3% reduction in cardiac output and a 37.6% reduction in mean arterial blood pressure were achieved. During profound low cardiac output, SMV stimulation with 33 Hz and 50 Hz improved cardiac output by 16.9% and 17.8%, improved the tension time index by 14.9% and 16.1%, and improved the endocardial viability ratio by 34.1% and 34.1%, respectively. These results again demonstrate the long-term effectiveness of SMVs as aortic counterpulsators. A valve in the efferent limb of the SMV system functions appropriately over time and may improve the efficiency of the system.

Functional evaluation of intrathoracic versus extrathoracic skeletal muscle ventricles

Skeletal muscle ventricles (SMVs) were constructed from the latissimus dorsi muscle in 10 dogs. In Group I (n = 5), SMVs were left in an extrathoracic position on the chest wall. In Group II (n = 5), SMVs were placed within the chest cavity. After a 3- to 4-week vascular delay period, SMVs were electrically preconditioned with 2 Hz continuous stimulation for 6 weeks. At a second procedure, SMVs were connected to a mock circulation system, and function was evaluated under differing conditions of preload and afterload. SMVs in Group II were significantly more compliant, as demonstrated by the end diastolic pressure volume relationship, than those in Group I (P < 0.01). SMVs in Group II were also capable of generating greater stroke work than those in Group I (P < 0.05). SMVs in Group II were also capable of greater stroke work than those in Group I at physiologic preloads (P < 0.05). These findings suggest that SMVs placed in an intrathoracic position exhibit better diastolic and systolic function.

Comparative study of fibrinolytic activity on 937 line after stimulation by interferon gamma, 1,25 dihydroxyvitamin D3 and their combination

Previous study showed that the secretion of urokinase (UK) by monoblastic cell line U 937 and the number of binding sites for urokinase and for plasminogen (Plg) on the cell surfaces were augmented by interferon gamma (INF tau). This induction led to an increase in fibrinolytic activity on cell surfaces. A similar increase was also observed when treating the U 937 cells with 1,25-dihydroxyvitamin D3 (1,25 (OH)2D3. Here we report that the combination of these two agents induced a 2.7 fold increase in the plasminogen activator activity on U 937 cell surfaces in comparison with 1 fold increase induced by INF tau and 1.3 fold increase by 1,25(OH)2D3. As evaluated by a flow cytometer, the increased fibrinolytic activity induced by the combination of INF tau and 1,25(OH)2D3 could be attributed to the increase of the number of binding sites both for UK (3.7 x 10(4) vs 1.2 x 10(4) per cell) and for Plg (16.2 x 10(4) vs 3.6 x 10(4) per cell), accompanied by an increased expression of CD 14, which is an antigen of differentiation on cell surfaces. These results suggest that the expression of urokinase receptors and plasminogen receptors may be coupled together by unknown intracellular mechanisms during cell differentiation, and support the idea that the concomitant regulation of these two receptors for UK and Plg is an important aspect in cell associated-fibrinolytic activity.

Update on skeletal muscle ventricles as aortic diastolic counterpulsators

Skeletal muscle ventricles are constructed from canine latissimus dorsi muscle. These skeletal muscle ventricles can be placed subcutaneously on the chest wall or inside the chest cavity. Skeletal muscle ventricles are connected to the descending thoracic aorta and activated to pump blood as aortic diastolic counterpulsators. The skeletal muscle ventricle in 1 animal pumped blood in the circulation for 27 months. Skeletal muscle ventricles can also function effectively under the condition of low cardiac output. Although thrombus has been detected in some skeletal muscle ventricles, thromboembolism to distal organs has been detected only rarely during the past few years. This research appears promising; however, skeletal muscle ventricle rupture remains a problem and currently accounts for about 30% of the mortality in the long-term experiments. It occurs at the site between the skeletal muscle ventricle outlet and the Dacron sewing ring that is necessary to connect conduits from the skeletal muscle ventricle to the animal's circulation. We believe that skeletal muscle ventricle rupture is likely to be a solvable problem. Once a solution has been found, skeletal muscle ventricles may be ready for clinical use in patients with chronic congestive heart failure.

Skeletal muscle ventricles: left ventricular apex to aorta configuration

Skeletal muscle ventricles (SMVs) were constructed from the latissimus dorsi muscle in 6 dogs. After 3 weeks of vascular delay followed by 6 weeks of 2-Hz continuous electrical conditioning, a valved conduit was placed between the left ventricular apex and the SMV and a second valved conduit, between the SMV and the aorta. The SMV was stimulated to contract during diastole at a 1:2 ratio with the heart. The SMV pumped 47% of the systemic blood flow initially (0.73 +/- 0.23 versus 1.54 +/- 0.42 L/min) and 40% after 3 hours. Skeletal muscle ventricle stimulation resulted in a 58% increase in mean diastolic pressure initially (52 +/- 9 to 82 +/- 11 mm Hg; p < 0.05) and a 73% increase (45 +/- 7 to 78 +/- 8 mm Hg) after 3 hours of continuous pumping. This was associated with a 68% increase in the endocardial viability ratio initially and a 63% increase at 3 hours. The systolic tension-time index decreased by 26% initially and 25% at 3 hours. This study indicates that the SMV configuration of left ventricular apex to aorta may be particularly suitable for left ventricular assist.

Ku autoantigen is the regulatory component of a template-associated protein kinase that phosphorylates RNA polymerase II

The carboxyl-terminal domain of RNA polymerase II contains a tandemly repeated heptapeptide sequence. Previous work has shown that this sequence is phosphorylated at multiple sites by a template-associated protein kinase, in a reaction that is closely associated with the initiation of RNA synthesis. We have purified this kinase to apparent homogeneity from human (HeLa) cells. The purified kinase phosphorylates native RNA polymerase II only in the presence of DNA and the general transcription factors TFIID (TBP), TFIIB, and TFIIF. Two kinase components are required for full activity: a catalytic component and a DNA-binding regulatory component. The regulatory component has been identified as Ku autoantigen, based on the molecular weights of its component polypeptides, its DNA-binding properties, and its reactivity with anti-Ku monoclonal antibodies. The Ku autoantigen recruits the catalytic component of the kinase to the template. Ku autoantigen has been previously proposed to interact with DNA by a characteristic bind-and-slide mechanism. This mode of interaction may provide a mechanism for targeting the kinase to the transcription complex and other DNA-bound substrates.

Skeletal muscle ventricles in circulation long-term: one hundred ninety-one to eight hundred thirty-six days

It has been shown previously that skeletal muscle ventricles fashioned from canine latissimus dorsi muscle can function as effective blood pumps. We describe four dogs that have been reported on before but have now had skeletal muscle ventricles functioning as effective aortic diastolic counterpulsators for 191 to 836 days. One dog remains well with a skeletal muscle ventricle that has been pumping in circulation for 194 days; there has been no evidence of thrombus in the skeletal muscle ventricle cavity or thromboembolism. None of the three dogs that died had evidence of peripheral embolization, although two of those dogs had thrombus within the cavity of the skeletal muscle ventricle. This study proves that skeletal muscle ventricles can function long-term in the circulation and maintain diastolic pressure augmentation beyond 2 years. To the best of our knowledge, the dog whose skeletal muscle ventricle pumped in circulation for 836 days represents the longest living laboratory animal or human with a functioning heart assist device.

Human general transcription factor IIH phosphorylates the C-terminal domain of RNA polymerase II

Phosphorylation of the carboxy-terminal domain of the largest subunit of RNA polymerase II is believed to control the transition from transcription initiation to elongation. The general transcription factor IIH (TFIIH) contains a kinase activity capable of phosphorylating this domain. Factors that promote the association of RNA polymerase II with the preinitiation complex stimulate this activity. The transcription factor IIE, which is required for the stable association of TFIIH with the preinitiation complex, affects the processivity of TFIIH kinase.

Skeletal muscle ventricles as left atrial-aortic pumps: short-term studies

In 5 dogs, skeletal muscle ventricles (SMVs) were constructed from the latissimus dorsi muscle and placed in the left hemithorax. After a 3-week vascular delay period, SMVs were electrically preconditioned with 2-Hz stimulation for 6 weeks. At a second operation, SMVs were connected between the left atrium and thoracic aorta by afferent and efferent aortic root homografts, and stimulated to contract in a 1:2 diastolic mode. At a mean left atrial pressure of 12.4 +/- 1.3 mm Hg and a burst stimulation frequency of 33 Hz, SMV stroke volume was initially 43% of that of the native left ventricle, achieving a flow equivalent to 21% of cardiac output (194 +/- 38 versus 902 +/- 85 mL/min). At 50-Hz stimulation, this figure rose to 27% (246 +/- 41 mL/min; p less than 0.05). Skeletal muscle ventricle power output (the product of stroke work and contraction rate) at 33 Hz was 0.016 +/- 0.003 W, increasing to 0.024 +/- 0.004 W at 50 Hz (p less than 0.05), corresponding to 14% and 22%, respectively, of left ventricular power output (0.11 +/- 0.012 W). After 4 hours of continuous pumping, four of the SMVs were still generating flows of more than 70% of starting values and more than 60% of initial power output. This study demonstrates that SMVs can function in the systemic circulation at physiologic left atrial preloads.

Skeletal muscle ventricles with improved thromboresistance: 28 weeks in circulation

Skeletal muscle ventricles (SMVs) were constructed from the left latissimus dorsi in 22 mongrel dogs. The configuration of these SMVs was different from those previously reported. The animals were divided into two groups: group A (n = 11) SMVs rested for 10 weeks after construction; group B (n = 11) SMVs rested for 18 weeks. At the end of the delay period, SMVs were tested in vivo with a mock circulation device. The SMVs in group B developed stroke work greater than those in group A. After acute testing, SMVs (n = 12) were connected to the descending thoracic aorta and stimulated to contract during diastole. Aortic diastolic counterpulsation was achieved in all dogs, with 9 animals surviving from 1 to beyond 28 weeks. In all of the dogs surviving 1 week or more, the SMVs remained free of thrombus. Aspirin was used as the only antithrombotic agent. Skeletal muscle ventricles in this study were able to develop stroke work similar to that previously reported, intermediate between that of the right and left ventricular stroke work, with a significantly decreased incidence of thromboembolism.

Surfactant protein C: hormonal control of SP-C mRNA levels in vitro

We have studied hormonal regulation of the surfactant protein C (SP-C) in fetal 18-dah rat lung explants. SP-C mRNA was detected in Northern blots with a specific rat SP-C cDNA probe and quantified by densitometry. Treatment of the explants with dexamethasone resulted in a dose-dependent increase of the SP-C mRNA level. Transcriptional assays have shown that the regulation of SP-C mRNA by dexamethasone involves a transcriptional step. Administration of the cAMP analogues, 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) or dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP), produced a dose-dependent increase of SP-C mRNA levels, with maximum stimulation observed at 200 microM. The thyroid hormone T3 had no effect on SP-C mRNA levels, whether administered alone or in combination with dexamethasone. Variation in the effects of the above hormones on three surfactant protein mRNAs, SP-A, SP-B and SP-C, indicates that the hormonal regulation of the surfactant proteins is a complex process and that each gene is, in part, differentially regulated.

Identification of Leishmania donovani isolates from different kala-azar foci in China by kDNA hybridization

kDNA sequence homology of Leishmania donovani isolates from three types of kala-azar foci in China were analyzed by using dot and Southern hybridization with biotin- and 32P-labelled probes. The results revealed kDNA sequence heterogeneity among Leishmania donovani isolates from the three kala-azar foci: sequence homology between isolates of hill and desert foci was higher than that between hill and plain foci isolates. The kDNA hybridization technique was also found to be specific and sensitive for direct identification of Leishmania in animal tissues. In a preliminary survey, kDNA hybridization of cutaneous tissue blots of 71 dogs from endemic regions showed a positive rate of 40.8%, and the rate of double positive cases (touch blot hybridization and bone marrow smear) reached 91.3%. The direct identification of Leishmania in tissues by kDNA hybridization seems to be a useful and convenient method for epidemiological study and clinical diagnosis, especially for species/strain characterization.

Specific interaction between the nonphosphorylated form of RNA polymerase II and the TATA-binding protein

Fractionation of a transcription-competent HeLa cell extract on a column containing one copy of the heptamer repeat (YSPTSPS) present in the carboxy-terminal domain (CTD) of the largest subunit of RNA polymerase II resulted in the loss of transcriptional activity. Fractionation of the extracts on columns containing mutations of the heptamer repeat was without effect. Such transcriptionally inactive extracts regained their ability to specifically transcribe different class II promoters upon the addition of human TFIID, recombinant yeast TATA-binding protein (TBP), or proteins bound to the column. Fractionation of RNA polymerase II on columns containing human or yeast TBP resulted in the specific retention of the nonphosphorylated form of RNA polymerase II. The phosphorylated form of the enzyme was unable to interact with TBP. The specific interaction of RNA polymerase II with TBP was mediated by the CTD of RNA polymerase II.

Skeletal muscle ventricles in the pulmonary circulation: up to 16 weeks' experience

Skeletal muscle ventricles (SMVs) were constructed from the right latissimus dorsi muscle of 8 mongrel dogs. After a 3-week vascular delay period, each SMV was electrically preconditioned with 2-Hz continuous stimulation of the thoracodorsal nerve for 6 weeks. A porcine-valved conduit was then anastomosed between the right ventricle and the SMV, with a second valved conduit connecting the SMV to the main pulmonary artery. The pulmonary artery was then ligated proximal to the conduit. The SMVs were stimulated to contract in 1:2 diastolic mode with a 33-Hz burst frequency. Effective right ventricular assist was achieved in all dogs. Cardiac output increased by 22.6% (1,799 +/- 97 versus 1,467 +/- 84 mL/min; p less than 0.001), systemic systolic arterial pressure by 9.3% (90.1 +/- 3.5 versus 82.4 +/- 3.9 mm Hg; p less than 0.005), and peak pulmonary artery pressure by 31.8% (27.8 +/- 2.0 versus 21.1 +/- 1.7 mm Hg; p less than 0.001) at the initiation of this study. In 6 dogs, effective right heart assist was sustained for periods of between 1 week and 12 weeks. Two dogs survived for longer than 3 months, though with evidence of deteriorating SMV function. These results demonstrate the feasibility of providing sustained right ventricular assist using this modified "Rastelli-SMV" configuration, which obviates the limitations imposed by low right atrial preload.

Factors involved in specific transcription by mammalian RNA polymerase II. Identification and characterization of factor IIH

Two new factors required for transcription of class II genes have been identified. These factors, TFIIH and TFIIJ, were required together with the previously described general factors (TFIIA, TFIIB, TFIID, TFIIE, and TFIIF) and RNA polymerase II for transcription of different class II genes. TFIIH was extensively purified, and the activity appeared to coelute with polypeptides of 33 and 95 kDa. The role of TFIIH and TFIIJ in preinitiation complex assembly was analyzed using mobility shift assays. It was found that TFIIH and TFIIJ association with the preinitiation complex was ordered and required the previous assembly of a preinitiation complex intermediate containing factors IID, IIB, IIF, IIE, and RNA polymerase II. A model for the ordered assembly of the general factors and RNA polymerase II is presented.

Hemostasis in patients undergoing extracorporeal circulation: the effect of aprotinin (Trasylol)

The administration of aprotinin during extracorporeal circulation (ECC) reduces blood loss. To explore the mechanism of this effect, a placebo-controlled double-blind study was performed in 20 patients (10 were administered with a high dose of aprotinin, 10 with placebo) undergoing a primary, elective operation of coronary artery bypass grafting (CABG) with ECC. Biological tests were performed at 4 different time points during the operation. A marked reduction in the placebo group of ristocetin-induced platelet agglutination (binding of von Willebrand factor [vWF] to platelet glycoprotein [GP] Ib) was shown during ECC and at the end of surgery, but not in the aprotinin group. This abnormality is not related to the hydrolysis of vWF or GP Ib, since washed platelets were resuspended in pooled normal plasma which provided a constant amount of vWF in this test and since the plasma concentration of the fragment of GP Ib (glycocalicin) did not correlate with this abnormality. Despite a high concentration of heparin (5-7 IU/ml) in patient's plasma during bypass, activation of blood coagulation in both groups was evidenced by an increase in ATm (thrombin-modified antithrombin III) level. The level of ATm in the placebo group reached a maximum at the end of ECC during rewarming, while in the aprotinin group, ATm level at this time point was significantly lower than in the control group. In comparison to the placebo group, the generation of the fibrin degradation products (DDE complexes) was inhibited by aprotinin during ECC, but the level of DDE complexes in the aprotinin group was slightly elevated after ECC, although much less than in the placebo group.(ABSTRACT TRUNCATED AT 250 WORDS)

[Incidence of venous air embolism in parturients during cesarean section with regional anesthesia]

The purpose of the study is to probe the situation of venous air embolism (VAE) and the accompanying complications occurring in Chinese parturients in Taiwan during Cesarean section. Sixty ASA physical status class I-II parturients who were subjected to cesarean section under regional anesthesia were evaluated. The sensor of the Doppler device was placed on the anterior chest to detect the rumbles of air when it came to pass, and simultaneously the signs and symptoms following VAE were observed. Our results demonstrated that the usual or normal Doppler heart sound changed in 38 parturients out of 60 (63.3%), and the alteration occurred very often when the uterus was being incised (81.6%), or sutured (97.4%), and concurred strong correlation with such signs and symptoms such as chest tightness or precordial pain (78.9%), shortness of breath (60.5%), and change of heart rate or blood pressure (86.8%). The method of anesthesia (spinal or epidural block) did not have effect on the occurrence of VAE, but different surgical approaches and different positions in which the patients were posed during operation did apparently bring about VAE of variable degree. Besides, supplying of oxygen could mitigate the symptoms produced by VAE. Consequently, the application of Doppler monitor during Cesarean section can detect VAE earlier and more efficiently and thus provides information timely treatment.

The nonphosphorylated form of RNA polymerase II preferentially associates with the preinitiation complex

The two forms of RNA polymerase II that exist in vivo, phosphorylated (IIO) and nonphosphorylated (IIA), were purified to apparent homogeneity from HeLa cells. The nonphosphorylated form preferentially binds to the preinitiation complex. RNA polymerase II in the complex was converted by a cellular protein kinase to the phosphorylated form.

The small subunit of transcription factor IIF recruits RNA polymerase II into the preinitiation complex

We found that transcription factor IIF mediates the association of RNA polymerase II with promoter sequences containing transcription factors IID, IIB, and IIA (DAB complex). The resulting DNA-protein complex contained RNA polymerase II and the two subunits of transcription factor IIF (RAP 30 and RAP 74). Cloned human RAP 30 was sufficient for the recruitment of RNA polymerase II to the DAB complex. This ability of RAP 30 to recruit RNA polymerase to a promoter is also a characteristic of sigma factors in prokaryotes.

Intrathoracic skeletal muscle ventricles: a feasibility study

For skeletal muscle ventricles (SMVs) to be applied clinically, it is likely that they will have to be placed within the chest. Ease of subsequent connection to the circulation, and avoidance of significant lung compression, are factors that could influence SMV size and shape in a way that may prejudice their ability to pump effectively at physiological preloads. In five dogs, specially designed SMVs were constructed from the latissimus dorsi muscle, and placed in the apex of the left hemithorax. After a 3-week delay, the muscle was preconditioned electrically by 2-Hz continuous stimulation for 6 weeks. At a later thoracotomy, this positioning of SMVs permitted easy surgical access to the heart and great vessels. SMVs were then connected to a mock circulation device for functional evaluation. As right-sided pumps, at a preload of 10 mmHg, SMVs generated a stroke volume (SV) and stroke work (SW) exceeding that of the native right ventricle (SV = 8.9 +/- 0.8 vs 7.9 +/- 0.6 mL; SW = 0.44 +/- 0.03 vs 0.20 ergs x 10(6)). As left-sided pumps, also at a preload of 10 mmHg, SMV SV, and SW was roughly half that of the left ventricle (SV = 3.7 +/- 0.2 vs 7.9 +/- 0.6 mL; SW = 0.29 +/- 0.03 vs 0.57 +/- 0.05 ergs x 10(6)). SMVs may conveniently be positioned inside the chest, where they have the potential to function as left or right heart assist devices.

Anthracycline immunoconjugates prepared by a site-specific linkage via an amino-dextran intermediate carrier

Anthracycline, either daunomycin or doxorubicin, was site specifically attached to the carbohydrate moiety of a monoclonal anticarcinoembryonic antigen antibody by using amino-dextran as the intermediate carrier. The reaction resulted in an immunoconjugate that contains approximately 20 to 25 molecules of drug per molecule of immunoglobulin G. Flow-cytometric studies revealed the retention of the antibody-binding activity. The immunoconjugate was cytotoxic to the target cells, as examined by the 75selenomethionine incorporation studies, and remained efficient for targeting a human colonic tumor (GW-39) in the nude mouse model. The conjugate possessed a greater antitumor activity against the subcutaneous tumor than either the free drug or an irrelevant antibody conjugate, and it was well tolerated by the animals at a much higher dose level than was the unconjugated drug.

Canine latissimus dorsi cardio-double myoplasty: acute feasibility study

Cardio-double myoplasty was performed in eight mongrel dogs. Both latissimus dorsi muscles were dissected from the chest wall and wrapped around the heart. They were then stimulated using an R wave synchronous stimulator. Hemodynamic measurements were obtained, first with the stimulator off and then with stimulator activated. After measuring hemodynamic effects in a normal heart, acute heart failure was induced by the infusion of propranolol (5 mg/kg). Hemodynamic data were then obtained in the same fashion. In a normal heart state, cardio-double myoplasty increased the cardiac output 9.9% +/- 2.24 (p less than 0.005), the left ventricular pressure 18.7% +/- 3.53 (p less than 0.001), the pulmonary artery pressure 72.2% +/- 25.4 (p less than 0.01), and the stroke volume 13.4% +/- 5.73 (p less than 0.05). In a failing heart, the cardiac output increased 21.6% +/- 3.34 (p less than 0.005), the left ventricular pressure increased 20.8% +/- 3.34 (p less than 0.005), the pulmonary artery pressure increased 87.2% +/- 39.9 (p less than 0.05), and the stroke volume increased 46.9% +/- 22.9 (p less than 0.05). The left ventricular end-diastolic pressure decreased slightly and the central venous pressure did not change in either the normal state or during cardiac failure. Cardio-double myoplasty resulted in a significant circulatory augmentation particularly in the setting of cardiac failure.

Temperature dependence of plasmin-induced activation or inhibition of human platelets

It is known that at 37 degrees C plasmin may have two opposite effects on platelets: at high concentrations (greater than 1.5 caseinolytic units [CU]/mL), plasmin activates platelets; at lower concentrations (0.1 to 1.0 CU/mL) it inhibits platelet activation induced by thrombin, collagen, or calcium ionophore A23187. In this study, we report that when lowering the incubation temperature to 22 degrees C, plasmin at low concentrations (0.1 to 0.5 CU/mL) fully activated platelets. When platelets were treated with 0.2 CU/mL of plasmin, lowering the incubation temperature from 37 degrees C to 22 degrees C resulted in an increase in the expression of fibrinogen receptors, in platelet release and aggregation. Thromboxane A2 was not generated by plasmin treatment at either temperature. Ultrastructural studies showed that platelets responded to low-dose plasmin at 37 degrees C by forming pseudopods, centralizing granules without fibrinogen release, whereas at 22 degrees C the same dose of plasmin caused platelet degranulation with the appearance of alpha-granule fibrinogen within the lumen of the surface connected canalicular system. In addition, at 22 degrees C plasmin at doses insufficient to induce platelet aggregation potentiated platelet response to thrombin. Thus, we suggest that plasmin may initiate both activating and inhibitory processes within platelets and that the change of temperature could influence this balance. These results may be of clinical relevance, because the fibrinolytic system was found activated during cardiopulmonary bypass in which the temperature of patient's blood circulation was reduced. This temperature-dependent behavior is also an interesting model for a further study on platelet response to serine proteinases.

Differential redistribution of platelet glycoproteins Ib and IIb-IIIa after plasmin stimulation

The subcellular localization of the platelet membrane receptors glycoproteins (GP) Ib and IIb/IIIa [corrected] has been studied within resting platelets by a combination of biochemical and cytochemical techniques. While both GPIb and GPIIb/IIIa are localized within the plasma membrane and surface-connected canalicular system (SCCS) membranes, only GPIIb/IIIa is present within the internal face of alpha-granular membranes. Previous studies demonstrated that plasmin can induce platelet stimulation and also decrease ristocetin-induced platelet aggregation; it was suggested that this was because of GPIb degradation by plasmin. In this study, the respective localizations of both GPIb and GPIIb/IIIa were visualized during in vitro plasmin stimulation of platelets. Generally, plasmin induced shape change, pseudopod formation, organelle centralization either with or without alpha-granule release depending on the conditions of stimulation. Plasmin treatment of platelets at 37 degrees C resulted in the disappearance of GPIb from the cell surface and its subsequent redistribution into the channels and vesicles of the SCCS with no significant modification of GPIIb/IIIa remaining on the plasma membrane. Within degranulated platelets, GPIIb/IIIa was expressed on the plasma membrane and within membranes of large vacuoles containing the alpha-granule proteins. GPIb was virtually absent from these structures and mainly restricted to the SCCS. Addition of cytochalasin D inhibited the migration of GPIb to the SCCS. Biochemical measurements confirmed that no important hydrolysis of GPIb had occurred because only very little amounts of glycocalicin were generated during the reaction. In conclusion, in plasmin-treated platelets GPIIb/IIIa is externalized to the plasma membrane while GPIb is internalized into the SCCS. Although previous studies have suggested that plasmin degrades GPIb, the reduction in ristocetin-induced aggregation may be explained by its apparent redistribution within the membranes of the SCCS.

Role of active center and lysine binding sites of plasmin in plasmin-induced platelet activation and disaggregation

Previous studies have shown that plasmin can activate platelets and can also disperse platelet aggregates by degradation of fibrinogen bound to platelets. In this study, the role of the active center and the lysine binding sites (LBS) of human plasmin in activating platelets and in dispersing platelet aggregates is investigated using aprotinin and the tripeptide Val-Phe-Lys-CH2Cl to inhibit the active center and using epsilon-aminocaproic acid (EACA) to specifically block the LBS. Our results show that the catalytic activity of plasmin is indispensable both for activating platelets and for dispersing platelet aggregates. Binding of plasmin to platelets through the LBS enhances its activating potential, since both EACA (1 mM) and Lys-plasminogen (molar ratio of plasminogen:plasmin at 2:1 to 4:1) inhibit plasmin-induced platelet activation, whereas Glu-plasminogen at a molar ratio of 15:1 had no effect. Furthermore, plasmin which lacks the LBS (miniplasmin), is about 3 fold less effective in activating platelets. However, plasmin binding through the LBS is not absolutely required to disperse platelet aggregates, since EACA at 30 mmol/l was unable to prevent disaggregation by plasmin (half disaggregation time: 40 min in the presence of EACA against 27 min in its absence). It also appeared that fibrinogen receptors on activated platelets are resistant to plasmin degradation, and that disaggregation of plasmin-induced platelet aggregates was much slower than the degradation of fibrinogen by plasmin.

Effect of dibenzo[a,c]cyclooctene lignans isolated from Fructus schizandrae on lipid peroxidation and anti-oxidative enzyme activity

The effect of nine dibenzo[a,c]cyclooctene lignans isolated from Fructus schizandrae on in vitro and in vivo lipid peroxidation of liver microsomes as well as on anti-oxidative enzyme activities were studied. Seven of the nine lignans (1 mM) were shown to inhibit Vit C/NADPH induced lipid peroxidation (malondialdehyde (MDA) formation) of rat liver microsomes. Of these compounds, schisanhenol (Sal), S(-)schizandrin C (S(-)sin C) and S(-)schizandrin B (S(-)sin B) were shown to be more potent than Vit E at the same concentration. Sal and Sin B were able to inhibit gossypol-induced superoxide anion generation in rat liver microsomes. In addition, oral administration of Sal and Sin B markedly reduced liver MDA formation induced by ethanol, 15 ml/kg in mice, and increased superoxide dismutase and catalase activities in rat liver cytosol. The data of this paper are in favor of the conclusion that some lignans, like Sal, have strong anti-oxidant activity. The mechanisms of anti-oxidant activity of the lignans were discussed.

KRDS, a new peptide derived from human lactotransferrin, inhibits platelet aggregation and release reaction

KRDS (Lys-Arg-Asp-Ser), a tetrapeptide from human lactotransferrin, was tested in vitro on human platelet function, and its effects were compared to those of RGDS, a tetrapeptide from human fibrinogen. Both peptides had a high probability of initiating a beta-turn and were highly hydrophilic. KRDS inhibited ADP-induced platelet aggregation [median inhibitory concentration (IC50) 350 microM] and fibrinogen binding (IC50 360 microM) to a lesser extent than RGDS (IC50 75 microM and 20 microM, respectively). Different from RGDS, thrombin-induced serotonin release was inhibited by KRDS (750 microM) on normal platelets (55 +/- 10%) and type I Glanzmann's thrombasthenia platelets (43% +/- 1). However, KRDS had no effect on cytoplasmic Ca2+ mobilization, inositol phospholipid metabolism or protein phosphorylation (myosin light chain P20 and P43). In contrast to RGDS, KRDS does not inhibit the binding of monoclonal antibody PAC-1 to activated platelets. KRDS and RGDS inhibited 4 beta-phorbol-12-myristate-13-acetate (PMA)-induced aggregation and fibrinogen binding, while proteins were normally phosphorylated. Thus, the tetrapeptide KRDS is (a) an inhibitor of serotonin release by a mechanism independent of protein phosphorylation and (b) an inhibitor of fibrinogen binding and, hence, aggregation by a mechanism that may not necessarily involve its direct binding to the glycoprotein IIb-IIIa-complex.

Absence of inhibition by lipoprotein (a) inhibition of tPA induced thrombolysis in a patient's plasma milieu

The increase in Lp(a) is strongly correlated with premature coronary artery disease. The Apo(a) has striking homology to plasminogen. It was found in an in vitro purified system that Lp(a) competes with both plasminogen and tissue-type plasminogen activator (tPA) for fibrin binding sites, thus resulting in a decrease in fibrin-dependent plasminogen activation. In this study, plasma fibrinolysis was studied in a young patient who had a consistently high level of Lp(a) (198 mg/dl) and had suffered from cerebral thrombophlebitis 12 months previously. The patient had normal levels of plasma plasminogen and fibrinogen. The euglobulin lysis time before and after venous occlusion was not prolonged, and after the addition of tPA to the patient's plasma or whole blood, the clot lysis time was normal. The same result was obtained when the patient's plasma was depleted of Lp(a) before clotting. When the patient's plasma serpins were inhibited, plasminogen activation by tPA in the presence of several fibrin concentrations was normal, suggesting that the formation of the ternary complex tPA - plasminogen - fibrin was not inhibited by the presence of high levels of Lp(a). It is concluded that a consistently high level of Lp(a) in this patient did not inhibit tPA-dependent fibrinolysis, and the thrombotic episode was not therefore related to deficient thrombolysis.

Interferon induction by human herpesvirus 6 in human mononuclear cells

Interferon (IFN) production after inoculation with human herpesvirus 6 (HHV-6) was studied in peripheral blood mononuclear cells from 10 HHV-6-seropositive healthy adults and five samples of cord blood mononuclear cells. When the cells were exposed to HHV-6 at a multiplicity of infection of 10(-2) 50% tissue culture infectious doses/cell, IFN activity was detected as early as 12 h after exposure to HHV-6, plateaued at days 2-5, and gradually decreased thereafter. IFN was also induced by ultraviolet-inactivated but not heat-inactivated HHV-6. The response of cord blood mononuclear cells was lower than that of the cells from healthy adults. The activity of all IFN samples was stable to acid and exclusively neutralized by anti-human IFN-alpha. The IFN-producing cell population was mainly non-T cells and monocytes. Furthermore, exogenous IFN suppressed HHV-6 replication. Production of IFN-alpha may be an important part of the host response to HHV-6.

[Effects of schizandrin B and schisanhenol on drug metabolizing-phase II enzymes and estradiol metabolism]

Intragastric gavage of schizandrin B (Sin B) and schisanhenol (Sal) 200 mg/kg once daily for 3 d significantly increased liver glutathione-S-transferase (GSH-S-T) and microsomal cytochrome P-450 in mice and rats. Sin B and Sal antagonized the increase of uterus weight induced by sc estradiol in ovariectomized, and decreased serum estradiol level in mice. RIA and HPLC showed an enhancement in [3H] estradiol metabolism by liver microsomes from Sin B- and Sal-treated mice. The results indicated that both Sin B and Sal have inductive actions on drug metabolizing-phase I and phase II enzymes in mice and rats.

Enhancement of human herpesvirus 6 replication in adult human lymphocytes by monoclonal antibody to CD3

The effect of monoclonal antibody to CD3 on human herpesvirus 6 (HHV-6) replication was assessed in adult peripheral blood mononuclear cells (PBMC) and in cord blood mononuclear cells (CBMC) by anticomplement immunofluorescence and Southern blot hybridization. Infection of CBMC by HHV-6 was productive; however, little or no infection was observed with PBMC from adults exposed to the virus even if stimulated by phytohemagglutinin. Monoclonal antibody to CD3 strongly enhanced HHV-6 replicative cycles in PBMC from adults.

1-Butyryl-glycerol: a novel angiogenesis factor secreted by differentiating adipocytes

Differentiation of adipocytes is accompanied by secretion of molecules stimulating angiogenesis in vivo and endothelial cell growth and motility in vitro. We demonstrate that the angiogenic and motility-stimulating activities secreted by adipocytes are separable from the endothelial cell mitogenic activity by fractionation of adipocyte-conditioned medium. The major differentiation-dependent angiogenic molecule was purified and identified by GCMS as 1-butyryl-glycerol (monobutyrin). Monobutyrin levels increase at least 200-fold during adipocyte differentiation and represent a major fraction of the total angiogenic activity. Synthetic monobutyrin shows the same spectrum of biological activities as the adipocyte-derived factor: stimulation of angiogenesis in vivo and microvascular endothelial cell motility in vitro, with no effect on endothelial cell proliferation. Angiogenesis is stimulated at doses as low as 20 pg when tested in the chick chorioallantoic membrane assay. These results strongly suggest that monobutyrin is a key regulatory molecule in an angiogenic process linked to normal cellular and tissue development.

Chloroquine's modulation of endothelial cell activity induced with basic fibroblast growth factor and human serum: effect on mitogenesis, protease production and cell migration

Chloroquine modulates the activity of cultured human microvascular endothelial (HOME) cells in a complex fashion. At concentrations of 5-25 microM, CQ inhibits basic fibroblast growth factor (bFGF-) and human serum-induced mitogenic activity in these cells, in a dose-dependent manner. The kinetics of CQ's inhibitory actions on serum-induced mitogenesis in HOME cells slowly develops with only 30% of maximum inhibition reached after 24 hours. In HOME cells grown in serum-free medium, CQ raised tissue-plasminogen activator antigen levels in cell extracts. There was also a potentiation of bFGF-induced t-PA production. The kinetics of CQ's stimulatory effect on t-PA production by HOME cells, suggest that this effect precedes its inhibitory actions on mitogenesis. This effect of CQ on t-PA generation in endothelial cells was susceptible to cycloheximide inhibition. In wound assays, HOME cell migration, induced with bFGF and HS, was potentiated by CQ.

Evaluation of the inhibition by heparin and hirudin of coagulation activation during r-tPA-induced thrombolysis

Thrombin bound to a fibrin clot remains active and poorly accessible to heparin-AT III complex. During fibrinolysis, thrombin is released as thrombin-FDP complex and is inactivated by heparin-AT III. However, as successive fibrin layers are removed, inaccessible molecules of thrombin are exposed at the surface of the residual clot, possibly contributing to the occurrence during thrombolytic therapy of coagulation that is poorly controlled by heparin. We have investigated the accessibility of fibrin-bound thrombin to hirudin. The results clearly show that two recombinant hirudin variants neutralize thrombin both in solution and fibrin bound. Furthermore, we have found that in in vitro models, hirudin present in the surrounding medium of a clot under lysis is more efficient than heparin in preventing the activation of coagulation. This observation suggests that hirudin may be effective in the prevention of the rethrombotic process frequently encountered during thrombolytic therapy.

[The diagnostic significance of isoantigens ABH in oral leukoplakia]

The ABH blood group isoantigens on the cell membrane of leukoplakia (LK) and normal oral tissue, squamous cell carcinoma and hyperkeratosis (HK) as controls were observed in this study and the results showed that there was a significant difference of the antigens in LK from those in normal tissue and HK, whereas, no significant difference between LK and carcinoma. Furthermore, the loss of antigens was in direct proportion with severity of dysplasia. The HRP-WGA technique was used to detect the WGA receptor on the cell membrane of LK, normal tissue and carcinoma. It was found that the receptor was present in the normal tissue, but decreased obviously and even disappeared in carcinoma. It should be emphasized that the receptor in LK also had some changes. Our findings show that when in mild dysplasia, it is possible to provide a clue to determine whether the dysplasia can be reversible through observation of the change of ABH antigens.

Parallel induction of fibrinolysis and receptors for plasminogen and urokinase by interferon gamma on U937 cells

A new cell sorter technique was employed to study the role of interferon gamma (INF gamma) in fibrinolysis induced by U937 monocytic cells. INF-gamma induced the differentiation of U937 cells as evidenced by the appearance of CD 14 antigen on the cell surface. Scatchard analysis and dose response curves showed a parallel increase in the number of receptors on U937 cells capable of accepting exogenous plasminogen and urokinase (UPA) synthetized by differentiating U937 monocytic cells. This would favour an activation of plasminogen by UPA. This adds a new parameter in the regulation of cell-mediated fibrinolysis and may be important in a number of biological processes.

Effects of hematopoietin-1 and interleukin 1 activities on early hematopoietic cells of the bone marrow

Hematopoietin-1 (H-1) was purified from the human cell line 5637 and two amino acid sequences were observed in the preparation. One sequence was identical to that of interleukin 1 alpha (IL 1 alpha) and the other to that of IL 1 beta. The action of recombinant IL 1 alpha and other hematopoietic growth factors was studied using (a) a high proliferative potential colony-forming cell assay that uses primitive hematopoietic precursors from bone marrow, and (b) a spleen colony-forming unit assay. The results indicate that the IL 1 alpha target cell population is different than the target cell populations of IL 3, granulocyte-macrophage colony-stimulating factor; that IL 1 alpha in combination with mononuclear phagocyte colony-stimulating factor provides a proliferative stimulus; and that IL 1 alpha has at least a survival-enhancing and possibly proliferation-inducing effect on primitive hematopoietic stem cells.

Enhanced expression of urokinase activity on U 937 cell line by 1,25-dihydroxyvitamin D3 induction

1,25 Dihydroxyvitamin D3 is a differentiation inducer for monocytic cell. It can induce a monoblastic cell line U937 to differentiate. In this paper, we report that by inducing the differentiation of U937, 1,25-dihydroxyvitamin D3 increased urokinase activity expression on U937 cell surfaces. After incubation of the cell with various concentrations of 1,25-dihydroxyvitamin D3, the cell line showed a remarkable progressively increasing membrane-associated urokinase activity in a dose dependent manner. On the contrary, plasminogen activator inhibitor activity which was found in the culture medium is not modified by the 1,25-dihydroxyvitamin D3 induction. This results suggests another role of 1,25-hydroxyvitamin D3 in the treatment of myelofibrosis, since enhanced plasmin generation can accelerate the activation of procollagenase. The induced plasmin and collagenase activities surrounding the monocytic cells may participate in the physiological and pathological events, especially in the connective tissue degradation.

Defective thrombolysis due to collagen incorporation in fibrin clots

The migration of fibroblasts into a clot may be responsible at least in part, for its organization, thus leading to a defective thrombolysis. We have shown that collagen incorporated in a fibrin clot induces a dramatic decrease in fibrinolysis. Despite the fact that plasminogen binds to collagen, tissue plasminogen activator induced plasminogen activation in the presence of fibrin is only slightly decreased by the presence of collagen. This rather suggests that collagen induces a modification in clot structure, by rendering fibrin less accessible to fibrinolytic enzyme.