Assay of 6-mercaptopurine and its metabolites in patient plasma by high-performance liquid chromatography with diode-array detection

A reversed-phase high-performance liquid chromatography (HPLC) method was developed to determine 6-mercaptopurine (MP) and seven of its metabolites (6-thioguanine, 6-thioxanthine, 6-mercaptopurine riboside, 6-thioguanosine, 6-thioxanthine riboside, 6-methylmercaptopurine and 6-methylmercaptopurine riboside) simultaneously in human plasma. A volume of 100 microl of plasma was used. Protein was removed from the sample by a simple and easy ultrafiltration step and ultrafiltrate was directly injected onto the HPLC system. Analytes were detected and confirmed with a diode-array detector before quantitation at 295 and 330 nm. The limit of detection for the analytes ranged from 20 to 50 nM. For the majority of patients receiving a 1 g/m2 MP intravenous infusion, MP and all metabolites except 6-thioguanine and 6-methylmercaptopurine riboside were present. This method serves as useful tool to characterize pharmacokinetics and pharmacodynamics of MP in oncology patients, and the small volume of plasma lends itself to pediatric studies.

Subclasses of warm autoantibody IgG in patients with autoimmune hemolytic anemia and their clinical implications

OBJECTIVE

To explore the mechanism of autoimmune hemolysis and establish a more sensitive test for autoimmune hemolytic anemia (AIHA).

METHODS

IgG subclasses were tested in 40 patients with idiopathic or secondary AIHA by Coombs test with monoclonal antibodies. Hb, TBil, RC and FHb, as hemolytic parameters, were used to analyze the clinical implications of subclasses of AIHA warm autoantibody IgG.

RESULTS

In most patients IgG incomplete warm autoantibody was IgG1 (27 patients), but IgG3 (20 patients), rarely IgG2 (14 patients) and IgG4 (9 patients) also occurred. Three groups were analyzed: Group A included 20 patients with IgG3; Group B included 14 patients with IgG1 bit without IgG3; Group C included 6 patients without IgG1 and IgG3. There were significant differences (P < 0.01) between groups in Hb, TBil, RC and FHb. Moreover, we also found that the sensitivity of Coombs test with polyclonal antiserums was 90.0%, while that of Coombs test with monoclonal antibodies was 97.5%. The effect of treatment was worst in patients with positive IgG3 autoantibody, whose hemolysis recurred frequently.

CONCLUSION

IgG3 autoantibody was the most effective in bringing about red cell destruction, IgG1 autoantibody was less effective, IgG2 even less, whereas IgG4 autoantibody was shown to hardly affect red cell survival. Coombs test with monoclonal antibodies was more sensitive than that with polyclonal antiserums. Patients' respondence to treatment correlated with the type of IgG subclasses.

Anti-inflammatory effects of total saponins of Panax notoginseng

AIM

To study the anti-inflammatory effects of total saponins of Panax notoginseng (PnS).

METHODS

Rat air-pouch acute inflammatory model was established with s.c. carrageenan (Car, 25 mg.kg-1). The protein content in exudate was measured. Micro-acid titration assay and radioimmunoassay (RIA) were applied respectively to investigate effects of PnS on phospholipase A2 (PLA2) activity and dinoprostone (Din) content in exudate. Fura-2 fluorescence technique was used to determine the intracellular free calcium concentration in neutrophils (Neu-[Ca2+]i).

RESULTS

At 12 h, PnS 60-240 mg.kg-1 i.p. reduced Neu counts, protein content [(7.7 +/- 1.3) to (4.4 +/- 1.4) g.L-1], and Din content [(1619 +/- 391) to (883 +/- 268) ng.L-1]; inhibited the PLA2 activity in exudate [(248 +/- 42) to (157 +/- 35) kU.L-1] in a dose-dependent manner. PnS 60, 120, and 240 mg.kg-1 lowered the level of Neu-[Ca2+]i with the inhibitory rate of 9.1%, 33.2%, and 39.4%, respectively.

CONCLUSION

PnS has an obvious anti-inflammatory effect and its mechanisms are related to the inhibition of the Neu-[Ca2+]i level and PLA2 activity, and reduction of Din content.

Localization of IgG in the normal and dystrophic rat retina after laser lesions

PURPOSE

To test the hypothesis that access to extravasated plasma protein IgG may influence photoreceptor survival following laser photocoagulation and to determine whether this correlates with the retinal glial reaction.

METHODS

A total of 45 rats (18 Royal College of Surgeons (RCS) dystrophic and 18 RCS-rdy+ congenic control) were used for this experiment. Nine non-lasered littermates of same age were used as controls. The superior retinas of postnatal day 23 rats were irradiated with a grid pattern of 40 argon green laser lesions of 50 microm in diameter and two powers (150 and 300 mW) for 0.2 s. At various times after laser lesions (up to 14 days), animals were perfused, the retinas snap frozen and sectioned on a cryostat. A one-step immunohistochemical technique was used by incubating with rabbit anti-rat IgG conjugated directly to horseradish peroxidase. Adjacent sections were processed using an antibody to glial fibrillary acidic protein (GFAP) by the standard avidin-biotin complex method.

RESULTS

The labelling pattern for extravasated IgG after laser lesion was very similar in both RCS and RCS-rdy+ rat retinas. At 6, 12 and 24 h after lesions, IgG immunoreactivity (IR) was very intense in the lesion core and flanks. The outer plexiform layer (OPL) and photoreceptor inner segments provided a ready pathway for lateral spread of IgG. However, in the outer nuclear layer (ONL), IgG localization was much more restricted. Despite very intense IgG IR in the ONL of the coagulated lesion core, there was always a very sharply delineated boundary where the label abruptly halted. The GFAP labelling in both RCS dystrophic and RCS-rdy+ congenic control rat retinas showed that this boundary was between normal and necrotic cells because there was a core where GFAP was not produced by Müller cells. By 2 days after lesions, the coagulated cells in the lesion core were being removed by phagocytic cells that were IgG IR. Labelled phagocytic cells were also found among the inner and outer segment region on the lesion flanks. There was still IgG IR in the lesion, but the label was faint. No IgG IR was found in the retina at 3, 4, 7 and 14 days after lesions. Absorption control with pure rat IgG showed the label to be specific.

CONCLUSIONS

The extravasated IgG was derived from the choroidal circulation because at no stage was IgG localized around the retinal vasculature. The IgG labelling was surprisingly widespread and, therefore, did not correlate with photoreceptor sparing, although it preceded the widespread Müller cell expression of GFAP and may, therefore, trigger glial reaction.

[Antilymphocyte globulin combining with cyclosporine A in the treatment of severe aplastic anemia]

OBJECTIVE

To explore more effective regimen for severe aplastic anemia (SAA).

METHODS

A prospective, randomized clinical trial was conducted to determine whether the outcome of SAA patients treated with the combination of antilymphocyte globulin(ALG) and cyclosporine A(CsA) (intensive immunosuppressive therapy, IIST) was better than that with ALG alone (non-intensive immunosuppressive therapy, NIIST).

RESULTS

The response rate of IIST group(83.7%) was significantly higher than that of NIIST group(57.6%), with a lower risk of early mortality and a shorter time to red cell transfusion independence. Furthermore, the recovery of bone marrow BFU-E and CFU-GM of the responding patients was more complete in IIST group than in NIIST group.

CONCLUSIONS

The treatment outcome was better with IIST than with NIIST for SAA.

Examining the immune response in sentinel lymph nodes of mice and men

Recently, it was recognized that an immune response develops along one of two major pathways. One leads to a destructive immune response (type 1), while the alternative leads to a nondestructive immune response (type 2). Our studies in animal models suggest that therapeutic vaccines induce a tumor-specific type 1 immune response while ineffective vaccines induce a type 2 response. These results have led us to examine the immune response in sentinel lymph nodes draining tumor vaccines of patients entered onto clinical trials for melanoma, breast and renal cell cancer.

[Clinical analysis of 164 cases Coombs test positive autoimmune hemolytic anemia]

OBJECTIVE

To analyze the clinical features and treatment outcomes of autoimmune hemolytic anemia (AIHA).

METHODS

Coombs test positive AIHA patients were retrospectively analyzed.

RESULTS

Patients with AIHA were predominantly female, secondary AIHA accounted for 49% of the total cases, mainly associated with connective tissue diseases. In most cases of AIHA, the anti-red cell antibodies were IgG plus C3, while patients with IgG plus IgM had more severe clinical manifestations. The response rate of adrenocortical hormones and cyclosporin A (CsA) was 90.9%.

CONCLUSION

Adrenocorticosteroids is still the first choice of therapy for AIHA, CsA can improve the response rate.

Treatment of severe aplastic anemia with an immunosuppressive agent plus recombinant human granulocyte-macrophage colony-stimulating factor and erythropoietin

To evaluate the therapeutic potential of hematopoietic growth factors (HGFs) during immunosuppressive treatment (IST) of severe aplastic anemia (SAA), 38 patients with newly diagnosed SAA received IST alone (group I), or IST plus recombinant human erythropoietin and granulocyte-macrophage colony-stimulating factor (rhEPO + rhGM-CSF) (group II). Eleven patients in each group received antilymphocyte globulin (ALG) for IST, and eight patients in each group received cyclosporine (CSA). Complete remission rates at one year were 26% and 74% for group I and group II patients, respectively. The ALG-treated subgroup showed the greatest differences between treatments. Compared with patients receiving ALG alone, patients treated with ALG plus HGFs had significantly better one-year survival (100% vs. 54.5%, P < 0.05), complete remission rates (91% vs. 36%, P < 0.05), more rapid and complete hematologic recovery, greater reductions in transfusion requirements, and lower infection rates. The data suggest a potential role for rhEPO + rhGM-CSF therapy in SAA patients receiving IST.

Direct gene transfer to the respiratory tract of mice with pure plasmid and lipid-formulated DNA

Direct gene transfer into the respiratory system could be carried out for either therapeutic or immunization purposes. Here we demonstrate that cells in the lung can take up and express plasmid DNA encoding a luciferase reporter gene whether it is administered in naked form or formulated with cationic liposomes. Depending on the lipid used, the transfection efficiency with liposome-formulated DNA may be higher, the same as, or less than that with pure plasmid DNA. Tetramethyltetraalkylspermine analogs with alkyl groups of 16 or 18 carbons and DMRIE/cholesterol formulations proved particularly effective. Similar results for reporter gene expression in the lung were obtained whether the DNA (naked or lipid formulated) was administered by indirect, noninvasive intranasal delivery (inhaled or instilled) or by invasive, direct intratracheal delivery (injected or via a cannula). Reporter gene expression peaks around 4 days, then falls off dramatically by 9 days. The dose-response is linear, at least up to 100 microg plasmid DNA, suggesting better transfection efficiencies might be realized if there was not a volume limitation. For a given dose of DNA, the best results are obtained when the DNA is mixed with the minimum amount of lipid that can complex it completely. These results are discussed in the context of direct gene transfer for either gene therapy or delivery of a mucosal DNA vaccine.

Cationic polymer and lipids enhance adenovirus-mediated gene transfer to rabbit carotid artery

BACKGROUND AND PURPOSE

Improvement of efficiency of gene transfer to endothelium could be useful for several applications. We tested the hypothesis that cationic nonviral molecules augment adenovirus-mediated gene transfer to blood vessels, perhaps by alteration of the surface charge of adenovirus and facilitation of binding to endothelium.

METHODS

Carotid arteries from rabbits were incubated in vitro for 0.5 to 2 hours with an adenoviral vector alone or noncovalent complexes of adenovirus with poly-L-lysine (a cationic polymer) or lipofectin (a cationic lipid). Binding of adenovirus to the vessels was evaluated immediately after incubation with virus, and assay of transgene (ss-galactosidase) activity and histochemistry were performed 24 hours after gene transfer. To determine whether cationic molecules can be used to augment alteration of vascular function by adenovirus-mediated gene transfer, we also examined effects on gene transfer of endothelial nitric oxide synthase.

RESULTS

Assay of ss-galactosidase activity indicated that both cationic molecules increased transgene expression in vessels by approximately 5- to 6-fold. In contrast, when endothelium was removed from the vessels after gene transfer, poly-L-lysine and lipofectin did not significantly increase transgene activity. Histochemistry for ss-galactosidase also suggested that the adenovirus-cationic molecule complexes augmented transgene expression mainly in the endothelium. In addition, we found that complexing adenovirus with cationic molecules increased binding of adenovirus to the vessels. After gene transfer with recombinant adenovirus containing endothelial nitric oxide synthase, calcium ionophore (A23187) produced greater relaxation of vessels treated with adenovirus complexed with poly-L-lysine or lipofectin than those treated with adenovirus alone.

CONCLUSIONS

Cationic molecules improve the efficiency of adenovirus-mediated gene transfer to blood vessels.

Study of the relatedness of isolates of Shigella flexneri and Shigella sonnei obtained in 1986 and 1987 and in 1994 and 1995 from Hong Kong

We used pulsed-field gel electrophoresis (PFGE) to study the genetic relatedness of 235 isolates of Shigella flexneri and Shigella sonnei collected in Hong Kong (97 isolates from 1986 and 1987 and 138 isolates from 1994 and 1995). Altogether, 13 gels were run with bacteriophage lambda ladder DNA (Pharmacia) as an external reference in every sixth lane, standardized reagents and methods, and isolates randomized for species and years. For quantitative illustration of the relationships within a large body of isolates, computer-generated dendrograms were used to determine the number of isolates in pulsotypes at Dice coefficients of similarity of 75% (PT75) and 50% (PT50). For S. flexneri, there was a significant difference in the distribution of isolates collected during the two periods in both PT75 and PT50, with 68% of isolates collected in 1994 and 1995 sharing a coefficient of similarity of >/=68%. For S. sonnei, a significant difference was observed in PT50 only. We also used Upholt's formula for an approximation of the fraction of nucleotide difference between isolates and Molecular Evolutionary Genetics Analysis to determine relative genetic distances. For both species, the relative genetic distances between isolates of the earlier collection period were significantly greater (P < 0.0001), i. e., they were further apart and therefore more diverse than those of the later period. We conclude that it is possible for a typical clinical laboratory to analyze a large amount of PFGE information on Shigella isolates obtained under controlled conditions. Such data analysis should enhance surveillance capabilities and give indications of further work to be done on various aspects of bacterial pathogenicity of the species.

[Experimental study of dahuang zhechong pills in the treatment of immunological liver fibrosis in rats]

OBJECTIVE

To study the effect of DHZC on liver fibrosis.

METHOD

Immuno-injured fibrosis in rats was induced by bovine serum albumin and DHZC was given during and after the model production respectively. Hepatic collagen contents, pathology of liver and serum hyaluronic acid were measured. Colchicine was used as control.

RESULT

It shows that the liver fibrosis rates of the DHZC treated group during and after the model production were 72.7% and 71.2% respectively, while those of the untreated and colchicine group were 92.3%-100%. Compared with the untreated group, there was a remarkable decrease of hepatic collagen contents in the DHZC-treated rats.

CONCLUSION

DHZC have thus been proved helpful in reversing liver fibrosis to some extent.

Vascular effects of LPS in mice deficient in expression of the gene for inducible nitric oxide synthase

The inducible isoform of nitric oxide synthase (iNOS) is expressed after systemic administration of lipopolysaccharide (LPS). The importance of expression of iNOS in blood vessels is poorly defined. Because nitric oxide from iNOS may alter vasomotor function, we examined effects of LPS on vasomotor function in carotid arteries from iNOS-deficient mice. We studied contraction of the carotid artery from wild-type and iNOS-deficient mice in vitro 12 h after injection of LPS (20 mg/kg ip). Contractile responses to PGF2alpha (3-30 microM) and thromboxane A2 analog (U-46619; 3-100 nM) were evaluated using vascular rings from mice treated with vehicle or LPS. Maximum force of contraction generated by rings in response to PGF2alpha was 0.39 +/- 0.02 and 0.25 +/- 0.01 (SE) g (n = 14) in vehicle and LPS-treated wild-type mice, respectively (P < 0.001 vs. vehicle). Thus LPS reduced constrictor responses in wild-type mice. Thiocitrulline and aminoguanidine (inhibitors of iNOS) improved contractile responses from LPS-treated wild-type vessels. Indomethacin also improved constrictor responses in arteries from wild-type mice injected with LPS. In contrast, contraction of the carotid arteries in response to PGF2alpha and U-46619 was not impaired in LPS-treated iNOS-deficient mice, and contraction was not altered by inhibitors of iNOS. Expression of iNOS mRNA was confirmed using RT-PCR in carotid arteries from wild-type mice after injection of LPS but not vehicle. PCR products for iNOS were not observed in iNOS-deficient mice. These findings provide the first direct evidence that iNOS mediates impairment of vascular contraction after treatment with LPS.

[Inhibition of human stomach cancer metastasis in vivo by anti-P-selectin monoclonal antibody]

OBJECTIVE

To study the role of cell adhesion molecule P-selectin monoclonal antibody (Mab) in tumor metastasis of an orthotopic implantation metastatic model.

METHODS

SCID mice were implanted orthotopically using SGC-7901 human stomach carcinoma intact tissue. Three days later, animals were given i.v. injections of PBS or P-selectin Mab (100 micrograms/injection) twice weekly for 3 weeks. 42 days after operation, all animals were sacrificed. Tissues from stomach and other organs were obtained for histopathological evaluation.

RESULTS

Ten of the animals (n = 11) treated with PBS developed metastatic tumors in the regional lymph nodes, liver, and lung. In contrast, 2 of the animals (n = 9) treated with P-selectin Mab developed metastatic tumors in the organs examined. The level of P selectin mRNA expression determined by RT-PCR in gastric carcinoma tissue of SCID mice with tumor metastas is was higher than that without metastasis.

CONCLUSIONS

The expression of P-selectin adhesion moleculeis associated with tumor metastasis, and the metastasis can be arrested by the Mab.

Increase in TUNEL positive cells in aorta from diabetic rats

TUNEL staining, which allows detection of fragmented DNA in situ, is commonly used as an indication of apoptosis. Recent studies suggest that apoptosis is increased in several pathophysiological conditions. In this study we examined the hypothesis that chronic diabetes is associated with an increase in TUNEL staining of the aorta. Diabetic rats were studied 4-5 months after injection of streptozotocin (50 mg/kg). Aorta of diabetic and control rats were examined for TUNEL staining, morphology by electron microscopy, and DNA contamination in RNA preparation by polymerase chain reaction (PCR). TUNEL staining of aortic sections showed a 6 fold increase of positive cells in the media of diabetic aorta (22 +/- 6%) (mean +/- SE) compared with aorta from age-matched controls (3.6 +/- 0.9%, p < 0.05). Electron microscopy demonstrated typical apoptotic cells and bodies in the media of aorta from diabetic but not control rats. DNA contamination was found in RNA prepared from diabetic aorta, which was detected using PCR, which is consistent with increased DNA fragmentation. Increased TUNEL staining was not observed in rats with hyperglycemia 3 days after injection of streptozotocin. In conclusion, severe chronic diabetes is associated with an increase in TUNEL staining, and perhaps apoptosis, in the aorta. We speculate that increased apoptosis may compensate for increased proliferative activity in diabetic blood vessels.

Endothelium-dependent relaxation of canine pulmonary artery endothelium after prolonged preservation

OBJECTIVE

Experiments were designed to investigate the effect of Euro-Collins (EC) solution and University of Wisconsin (UW) solution on function of pulmonary arterial endothelium.

METHODS

Third order canine pulmonary artery segments were preserved in cold (4 degrees C) UW (group 1, n = 8) or EC (group 2, n = 9) solutions for 16 hours. The preserved (group 1 and 2) and control (group 3, n = 7) pulmonary arterial segments with and without endothelium were studied in vitro in organ chambers to measure isometric tension.

RESULTS

The endothelium-dependent relaxation to acetylcholine and adenosine diphosphate of group 1 and 3 were significantly better than those of group 2.

CONCLUSIONS

We concluded that endothelium-dependent relaxation of canine pulmonary arterial endothelium to receptor-dependent acetylcholine and adenosine diphosphate were impaired after preservation with Euro-Collins solution. However, endothelium-dependent relaxation of pulmonary segments were well maintained after preservation with University of Wisconsin solution.

Cellular delivery of CNTF but not NT-4/5 prevents degeneration of striatal neurons in a rodent model of Huntington's disease

The delivery of neurotrophic factors to the central nervous system (CNS) has gained considerable attention as a potential treatment strategy for neurodegenerative disorders such as Huntington's disease (HD). In the present study, we directly compared the ability of two neurotrophic factors, ciliary neurotrophic factor (CNTF), and neurotrophin-4/5 (NT-4/5), to prevent the degeneration of striatal neurons following intrastriatal injections of quinolinic acid (QA). Expression vectors containing either the human CNTF or NT-4/5 gene were transfected into a baby hamster kidney fibroblast cell line (BHK). Using a polymeric device, encapsulated BHK-control cells and those secreting either CNTF (BHK-CNTF) or NT-4/5 (BHK-NT-4/5) were transplanted unilaterally into the rat lateral ventricle. Seven days later, the same animals received unilateral injections of QA (225 nmol) into the ipsilateral striatum. Nissl-stained sections demonstrated that the BHK-CNTF cells significantly reduced the volume of striatal damage produced by QA. Quantitative analysis of striatal neurons further demonstrated that both choline acetyltransferase (ChAT)- and glutamic acid decarboxylase (GAD)-immunoreactive neurons were protected by CNTF implants. In contrast, the volume of striatal damage and loss of striatal ChAT and GAD-positive neurons in animals receiving BHK-NT-4/5 implants did not differ from control-implanted animals. These results help better define the scope of neuronal protection that can be afforded following cellular delivery of various neurotrophic factors. Moreover, these data further support the concept that implants of polymer-encapsulated CNTF-releasing cells can be used to protect striatal neurons from excitotoxic damage, and that this strategy may ultimately prove relevant for the treatment of HD.

Immunocytochemical localization of basic fibroblast growth factor and glial fibrillary acidic protein after laser photocoagulation in the Royal College of Surgeons rat

PURPOSE

Argon laser photocoagulation slows photoreceptor degeneration in the Royal College of Surgeons (RCS) rat, as does intravitreal injection of basic fibroblast growth factor (bFGF). We hypothesize that up-regulation of retinal bFGF is a consequence of laser lesioning in RCS rats. Therefore, we examined the localization of bFGF after laser and correlated this with Mailer cell glial fibrillary acidic protein (GFAP) expression, which is known to increase after injury.

METHODS

A total of 34 RCS rats at postnatal day 23 were anaesthetized (ketamine 40 mg/kg) and their retinas were irradiated with a grid pattern of 40 non-overlapping argon green lesions with a power of 120 mW for 0.2 s using a 50 microm spot size. At 0, 6, 12, 24 and 48 h and 7, 14 and 21 days post-lesion, rats were anaesthetized and their eyes were enucleated and cryostat sectioned and the sections were processed using either an antibody to bFGF or GFAP using the standard avidin-biotinylated peroxidase complex method. Five age-matched RCS rats without laser lesions served as controls.

RESULTS

Basic fibroblast growth factor immunoreactivity (IR) was normally located within cells in the ganglion cell layer inner nuclear layer and in retinal pigment epithelium cells and in the extracellular matrix/cell membranes of the outer nuclear layer (ONL). In lasered retinas, there was elevated bFGF-IR in the coagulated outer segments for the first 24 h. Retinal blood vessels/Müller cells/astrocytes were moderately labelled in and near each lesion immediately after lesion and became more intense after 48 h and persisted for at least 21 days. There was an elevation of bFGF-IR in the ONL on the lesion flanks at 14 days. Muller cell GFAP-IR was first detected at 6 h post-lesion and spread for a considerable distance beyond the lesion site. At 7 and 14 days, Müller cells at the lesion site had sprouted, while those on the flanks were still GFAP-IR.

CONCLUSIONS

Following laser lesion there was an increase in bFGF at the lesion core only for the first 24 h. However, elevated levels of bFGF were observed in the ONL at 14 days, which extended into the lesion flanks for a similar distance to that over which increased photoreceptor survival is found. These results provide support for the hypothesis that laser lesions induce bFGF and this may be the mechanism whereby photoreceptors are spared. Müller cell activation is consistent with growth factor stimulation, but was more widespread than the bFGF changes in ONL. However, blood vessel labelling was similarly widespread and so the responses may be linked between Müller cell GFAP reaction and blood vessel bFGF localization after laser lesions.

Constitutive telomerase activity in cells with tissue-renewing potential from estrogen-regulated rat tissues

To investigate the role of telomerase in estrogen-regulated rodent tissues, we assayed the activity levels of this enzyme and measured cell proliferation and indicators of cellularity in vagina, mammary gland, and uterus from virgin, pregnant, ovariectomized, and ovariectomized estradiol-treated rats. No association was observed between telomerase activity and increased cell proliferation. Telomerase activity was significantly higher (P=0.003) in vagina obtained from ovariectomized rats (very low proliferation) than in vagina from ovariectomized and estradiol-treated rats (high proliferation, high differentiation). The high telomerase levels observed in vagina from ovariectomized rats indicates that the same epithelial compartment (i.e., basal layer) that has the potential to reconstitute the epithelium also contains the cells that express telomerase. The lower telomerase activity in the keratinized (differentiated) vagina was probably due to dilution of the number of telomerase-producing cells by the terminally differentiated non-telomerase-producing cells. Similar results were observed in uterus from ovariectomized versus ovariectomized and estradiol-treated rats. Telomerase activity was highest in uterus from pregnant rats. Telomerase levels in samples from total mammary gland fat pads varied considerably between groups and appeared to be representative of the amount of epithelium present in the sample. Interestingly, when mammary gland samples from the same animals were obtained from pure epithelial organoid preparations, no differences in telomerase activity could be distinguished between animals or groups. Overall these data suggest that telomerase activity, particularly in rat vagina and uterus, appears to be associated with a cell subpopulation showing proliferative and tissue reconstitution potential and not directly associated with proliferation status per se.

Immunophenotype of myeloid cells in myelodysplastic syndromes and its clinical implications

OBJECTIVE

To explore the immunophenotype of myeloid cells in myelodysplastic syndyomes (MDS) and its clinical implications.

METHODS

A panel of monoclonal antibody was used to detect CD13+, CD33+, CD15+ and CD14+ antigens on the membrane surfaces of myeloid cells in the bone marrow from 51 MDS, 21 aplastic anemia (AA), 21 paroxysmal nocturnal hemoglobinuria (PNH) patients. 10 acute myeloblastic leukemia (AML) patients and 15 normal subjects by immunoenzymatic assay. The morphology and chromosome karyotype of bone marrow cells of MDS patients were also examined.

RESULTS

CD14+, CD13+ and CD33+ cells in the bone marrow were more in MDS patients than in normal controls, AA patients and PNH patients. CD15+ cells in the bone marrow were less in MDS patients than in normal controls.

CONCLUSIONS

The percentages of CD14+, CD13+ and CD33+ positive cells in the bone marrow of MDS patients were related to the percentage of myeloblasts, the chromosomal aberrations and the response to treatment. It indicated that there is immunophenotypic misexpression of myeloid cells in MDS patients. Immunophenotype analysis of myeloid cells might be useful for the diagnosis and treatment of MDS patients.

Telomerase and cell proliferation in mouse skin papillomas

The progression of chemically induced mouse skin papillomas is paralleled by an increase in telomerase activity. In this study, we compared telomerase activity and rate of cell proliferation in papillomas obtained early versus late in papilloma progression. Eighteen early papillomas (after 15 wk of promotion) showed no evidence of telomerase activity, and their average cell proliferation index was 26.6% +/- 6.3. On the other hand, most of the papillomas harvested after 25 wk of promotion showed high levels of telomerase activity, but their average cell proliferation index (30.8% +/- 6.2) was not different from that of the early lesions. We concluded that there appears to be no association between the level of telomerase activity observed in mouse skin papillomas and the rate of cell proliferation of each individual tumor. Telomerase expression may indicate the existence of more abundant tumor subpopulations in advanced papillomas with proliferative potential for autonomous growth.

Rheological analysis of the formation of rosettes by red blood cells parasitized by Plasmodium falciparum

Red blood cells infected by mature malarial parasites of the species Plasmodium falciparum can adhere to non-parasitized red cells (rosetting) and also to endothelial cells (cytoadhesion). To investigate how the circulation might influence rosetting, we studied formation of rosettes in cell suspensions sheared in a cone-and-plate viscometer, and the ability of flowing non-parasitized cells to bind to parasitized cells already adherent to a surface. After rosettes of strain R29 had been disrupted with fucoidan, they reformed slowly under stationary conditions but more rapidly in suspensions sheared at low stress (about 0.1-0.2 Pa). Strain Malayan Camp gave a lower rosetting frequency which actually increased at low shear. Increasing shear stress was associated with reduction in rosette formation, although rosetting occurred at >1 Pa, suggesting that rosettes could form in the systemic circulation. Rosetting inhibited adhesion of flowing parasitized cells to immobilized platelets (which express the cytoadhesion receptor CD36), as evidenced by increased adhesion after disruption of rosettes. The de-rosetted adherent cells parasitized by R29 supported only a low level of rosetting when non-parasitized cells were flowed over them at a wall shear of 0.1 Pa, with little increase if the stress was decreased to 0.05 Pa. Rosettes formed in the circulation might obstruct microvessels and inhibit cytoadhesion if they reached venules. However, if cytoadhesion occurred before rosetting, then adherent cells should not efficiently form rosettes.

Generation and transplantation of EGF-responsive neural stem cells derived from GFAP-hNGF transgenic mice

EGF-responsive neural stem cells isolated from murine striatum have the capacity to differentiate into both neurons and glia in vitro. Genetic modification of these cells is hindered by a number of problems such as gene stability and transfection efficiency. To circumvent these problems we generated transgenic mice in which the human GFAP promoter directs the expression of human NGF. Neural stem cells isolated from the forebrain of these transgenic animals proliferate and form clusters, which appear identical to stem cells generated from control animals. Upon differentiation in vitro, the transgenic stem cell-derived astrocytes express and secrete bioactive hNGF. Undifferentiated GFAP-hNGF or control stem cells were transplanted into the striatum of adult rats. One and 3 weeks after transplantation, hNGF was detected immunocytochemically in an halo around the transplant sites. In GFAP-hNGF-grafted animals, intrinsic striatal neurons proximal to the graft appear to have taken up hNGF secreted by the grafted cells. Ipsilateral to implants of GFAP-hNGF-secreting cells, choline acetyltransferase-immunoreactive neurons within the striatum were hypertrophied relative to the contralateral side or control-grafted animals. Further, GFAP-hNGF-grafted rats displayed a robust sprouting of p75 neurotrophin receptor-positive fibers emanating from the underlying basal forebrain. These studies indicate that EGF-responsive stem cells which secrete hNGF under the direction of the GFAP promoter display in vitro and in vivo properties similar to that seen following other methods of NGF delivery and this source of cells may provide an excellent avenue for delivery of neurotrophins such as NGF to the central nervous system.

[Colony formation of bone marrow hematopoietic progenitor cells in patients with severe aplastic anemia and its relation to the results of immunosuppressive therapy]

OBJECTIVE

To explore the defect of hematopoietic stem cell and analyze the relationship between the colony formation capacity of bone marrow hematopoietic progenitor cells and the results of immunosuppressive therapy (IST) in severe aplastic anemia (SAA) patients.

METHODS

Methylcellulose semisolid culture was used.

RESULTS

Thirty patients with SAA at diagnosis were studied. In 90% of the patients, the CFU-E and CFU-GM yields were strikingly decreased and in 56.7% of the patients there was no colony formation at all. Nevertheless, there was still 10% of the patients having normal CFU-E, BFU-E or/ and CFU-GM yields. After IST, 59.1% of the patients showed colony formation improvement. The difference between the results obtained pre- and post-IST(for CFU-E and BFU-E, P < 0.01, for CFU-GM, P < 0.05) was significant. In the majority of the patients, the colony formation capacities were still under the normal post-IST. Moreover, 22.7% of the patients remained no colony formation post-IST. The IST response rates between the patients with or without colony formation had no statistically difference (80% versus 50%, P < 0.05). The increment of colony formation appeared later than the therapeutic effect did, but frequently concurred with the appearance of magkaryocytes in the bone marrow smear.

CONCLUSION

In the majority of SAA patients, the hematopoietic stem cells or progenitors were defective perhaps caused by immune damage; IST can improve the hematopoiesis in vitro and in vivo of SAA patients.

Augmented adenovirus-mediated gene transfer to atherosclerotic vessels

Vascular endothelium is an important target for gene transfer in atherosclerosis. In this study, we examined gene transfer to normal and atherosclerotic blood vessels from two species, using an organ culture method. Using normal aorta, we determined optimal dose, duration of exposure to adenovirus, and duration of incubation of vessels in tissue culture. Aortas from normal and atherosclerotic monkeys were cut into rings and incubated for 2 hours with a recombinant adenovirus, carrying the reporter gene for beta-galactosidase driven by a cytomegalovirus (CMV) promoter. After 20 hours of incubation, transgene expression was assessed with a morphometric method after histochemical staining and a chemiluminescent assay of enzyme activity. Expression of beta-galactosidase after histochemical staining, expressed as percentage of total cells, was similar in adventitial cells of normal monkeys (21 +/- 4%, mean +/- SE%) and atherosclerotic monkeys (25 +/- 12%). Transgene expression in endothelium was higher in atherosclerotic than in normal vessel (53 +/- 3% versus 27 +/- 7%, P < .05). Chemiluminescent assay indicated greater beta-galactosidase activity (2.5 +/- 0.6 mU/mg of protein) in the intima and media of atherosclerotic than normal vessels (0.6 +/- 0.2 mU/mg of protein, P < .05). Aortas from normal (n = 6) and atherosclerotic (n = 5) rabbits also were examined. Transgene expression (after histochemical staining) in endothelium was much greater in atherosclerotic than normal rabbits (39 +/- 3% versus 9 +/- 2%, P < .05) and expression in adventitial cells was similar (normal 23 +/- 2%, atherosclerotic 24 +/- 4%). Chemiluminescent assay indicated greater beta-galactosidase activity (1.2 +/- 0.4 mU/mg of protein) in the intima and media of atherosclerotic than normal vessels (0.2 +/- 0.1 mU/mg protein, P < .05). These findings suggest that an adenoviral vector with a CMV promoter provides similar transgene expression in adventitia of both normal and atherosclerotic vessels. Gene transfer to the endothelium was much more effective in atherosclerotic than in normal vessels. Thus it may be possible to achieve greater transgene expression in atherosclerotic than in normal arteries.

Altered vascular function after adenovirus-mediated overexpression of endothelial nitric oxide synthase

Gene transfer with replication-deficient adenovirus is a potentially useful tool to study vascular biology. We have constructed a replication-deficient adenovirus (AdRSVeNOS) that carries cDNA for endothelial nitric oxide synthase (eNOS). Transfection of COS-1 cells with AdRSVeNOS increased nitric oxide synthase activity (measured as production of L-citrulline from L-arginine) that was calcium dependent and inhibited by N omega-nitro-L-arginine methyl ester. To investigate effects of overexpression of eNOS on vascular function, we incubated common carotid arteries from rabbits in organ culture with AdRSVeNOS or AdRSV beta gal encoding beta-galactosidase. Transgene expression and responses to vasoactive agents were examined 1 day after transduction. Histochemical staining of beta-galactosidase and immunohistochemistry for eNOS indicated transgene expression in endothelium and adventitial cells. After precontraction with phenylephrine, vessels treated with AdRSVeNOS demonstrated greater relaxation to acetylcholine than vessels treated with vehicle or AdRSV beta gal. Relaxation to calcium ionophore A-23187 was much greater in vessels treated with AdRSVeNOS than in vessels treated with vehicle or AdRSV beta gal. Augmented relaxation in response to A-23187 was also observed after denudation of endothelium in vessels treated with AdRSVeNOS and was inhibited by N omega-nitro-L-arginine. Thus vasorelaxation in response to stimuli that release nitric oxide is augmented after adenovirus-mediated overexpression of eNOS. Transgene expression in adventitial cells appears to be sufficient to alter vasomotor function.

Continuous antegrade warm blood cardioplegia attenuates augmented coronary endothelium-dependent contraction after cardiac global ischemia and reperfusion

BACKGROUND

Experiments were designed to evaluate the effect of warm blood cardioplegia on endothelium-dependent contraction of the coronary endothelium after cardiac global ischemia and reperfusion.

METHOD

Dogs (n = 12 in each group) were exposed to extracorporeal circulation with the body temperature at 37 degrees C (group 1) or 28 degrees C (groups 2 and 3). The ascending aorta was crossclamped for 120 minutes while continuous infusion of warm blood cardioplegec solution (group 1) or intermittent infusion of cold (4 degrees C) crystalloid cardioplegic solution (group 2) was performed via the coronary arteries through the aortic root. Cardioplegic solution was not used in group 3 animals. The heart was then allowed to function for 60 minutes of reperfusion. Reperfused (groups 1, 2, and 3) and control (group 4) coronary arteries were then harvested for study.

RESULTS

Perfusate hypoxia caused endothelium-dependent contraction in the arteries of all four groups that could be attenuated by NG-monomethyl-L-arginine (L-NMMA) or L-NMMA plus D-arginine, but not by L-NMMA plus L-arginine or endothelin receptor A and B antagonist PD 145065. The endothelium-dependent contraction results in groups 2 and 3 (75% +/- 4% and 80% +/- 5%, respectively) were significantly greater than those in groups 1 and 4 (15% +/- 3% and 18% +/- 5%, respectively). Scanning electron microscope studies showed that platelet adhesion and aggregation, areas of microthrombi, disruption of endothelial cells, and separation of the intercellular junction could be found in coronary segments from groups 2 and 3, but not in vessels from groups 1 and 4.

CONCLUSION

These experiments suggest that global ischemia and reperfusion enhances hypoxia-mediated endothelium-dependent contraction of the coronary endothelium and damages the ultrastructure. These kinds of changes can be prevented by continuous antegrade infusion of warm blood cardioplegic solution during global ischemia.

[Colony-stimulating activities of serum from patients with severe aplastic anemia]

OBJECTIVE

To investigate the correlation between colony-stimulating activities of serum from patients with severe aplastic anemia (SAA) and their responses to immunosuppressive therapy (IST).

METHODS

In vitro effects of sera from SAA patients before and after IST and from normal subjects on human marrow colony growth were examined in a semisolid methylcellulose culture system for burst promoting activity (BPA) and granulocyte/macrophage colony-stimulating activity (GM-CSA). Serum erythropoietin (Epo) level was also measured by ELISA method before and after IST in SAA patients.

RESULTS

Serum BPAs in SAA patients at diagnosis were significantly higher than that in normal controls (P<0.001), but serum GM-CSAs in 13 of 22 SAA patients were normal,and in 9 of 22 extremely low as compared with normal values. After IST, serum BPA and GM-CSA in SAA patients had no changes. Serum Epo levels in SAA patients at diagnosis were significantly higher than that in normal controls (P<0.001). After IST,serum Epo levels declined in responded patients, while further increased in nonresponded.

CONCLUSION

Serum GM-CSA of SAA patients was a predictive factor for responsiveness to IST, and a normal value was associated with a good response.

[Immunophenotyping study on the blood cells of the patients with paroxysmal nocturnal hemoglobinuria]

OBJECTIVE

To detect the expression of glycosyl-phosphatidyl-inositol (GPI) anchored protein on the blood cell membrane and its implication in the diagnosis of paroxysmal nocturnal hemoglobinuria (PNH).

METHODS

The GPI anchored protein was detected by indirect immunofluorescence method with a panel of monoclonal antibodies (CD55, CD59, CD16, CD58, HIR2, CD15, CD2) in 22 PNH patients.

RESULTS

The abnormal granulocytes and erythrocytes with deficient GPI anchored proteins were identified in all PNH patients whether the routine hemolysis tests for PNH, including Ham test and mCLST, were positive or negative. However, lymphocytes with PNH-defect were found in only 14 patients.

CONCLUSION

GPI anchored protein assay provided sensitive and specific method for the diagnosis of PNH.

[HLA-DR-positive T lymphocytes in the bone marrow and peripheral blood of patients with severe aplastic anemia and their in vitro inhibitory effecton BFU-E and CFU-GM]

OBJECTIVE

[corrected] To elucidate the role of immunodysfunction in the pathogenesis of severe aplastic anemia (SAA).

METHODS

HLA-DR+ T cells were detected in bone marrow (BM) and peripheral blood (PB) of 20 SAA patients and controls (9 for BM and 11 for PB). PHA-LYCM conditioned medium was prepared, and its in vitro effect on normal bone marrow BFU-E and CFU-GM was studied.

RESULTS

The percentages of HLA-DR+ T lymphocytes in BM and PB of newly diagnosed SAA patients were significantly higher than that of controls (P<0.001), and that of recovered SAA (rSAA) patients after ALG therapy (P<0.05). Compared with controls, the PBA-LYCMs from newly diagnosed SAA patients showed significant inhibitory effect on normal BFU-E and CFU-GM (P<0.001).

CONCLUSION

The activated T lymphocyte may play an important role in the pathogenesis of SAA.

[Correlation between the serum levels of interleukin-2 and soluble interleukin-2 receptor and the response to immunosuppressive therapy in severe aplastic anemia patients]

OBJECTIVE

To explore factors influencing the effectiveness of immunosuppressive therapy in severe aplastic anemia (SAA).

METHODS

The serum levels of interleukin-2 (IL-2) and soluble IL-2 receptor (sIL-2R) of 22 SAA patients and 15 normal controls were measured by immunoenzyme assay.

RESULTS

Comparing with the normal controls, 40.9% and 63.6% of the SAA patients had higher serum levels of IL-2 (>840ng/L) and of sIL 2R (>320 x 10(3) U/L), respectively. Those who had higher IL-2 levels and higher sIL-2R levels got better responses to cyclosporin A(CsA) and CsA plus antilymphocyte globulin (ALG).

CONCLUSION

The serum levels of IL-2 and sIL-2R were correlated with the responsiveness to immunosuppressive therapy in SAA patients and might be useful for directing treatment.

Protective effect of encapsulated cells producing neurotrophic factor CNTF in a monkey model of Huntington's disease

Huntington's disease is a genetic disorder that results from degeneration of striatal neurons, particularly those containing GABA (gamma-aminobutyric acid). There is no effective treatment for preventing or slowing this neuronal degeneration. Ciliary neurotrophic factor (CNTF) is a trophic factor for striatal neurons and therefore a potential therapeutic agent for Huntington's disease. Here we evaluate CNTF as a neuroprotective agent in a nonhuman primate model of Huntington's disease. We gave cynomolgus monkeys intrastriatal implants of polymer-encapsulated baby hamster kidney fibroblasts that had been genetically modified to secrete human CNTF. One week later, monkeys received unilateral injections of quinolinic acid into the previously implanted striatum to reproduce the neuropathology seen in Huntington's disease. Human CNTF was found to exert a neuroprotective effect on several populations of striatal cells, including GABAergic, cholinergic and diaphorase-positive neurons which were all destined to die following administration of quinolinic acid. Human CNTF also prevented the retrograde atrophy of layer V neurons in motor cortex and exerted a significant protective effect on the GABAergic innervation of the two important target fields of the striatal output neurons (the globus pallidus and pars reticulata of the substantia nigra). Our results show that human CNTF has a trophic influence on degenerating striatal neurons as well as on critical non-striatal regions such as the cerebral cortex, supporting the idea that human CNTF may help to prevent the degeneration of vulnerable striatal populations and cortical-striatal basal ganglia circuits in Huntington's disease.

Retinal GFAP and bFGF expression after multiple argon laser photocoagulation injuries assessed by both immunoreactivity and mRNA levels

The expression of GFAP and bFGF after retinal photocoagulation injury in the rat was assessed by immunocytochemistry and reverse transcriptase PCR. Beta-actin mRNA expression was unaltered after injury and was therefore a good control for the quality of the RNA samples and the PCR reaction. GFAP mRNA increased from undetectable levels in normal retina to relatively high levels at 24 and 48 hr after injury, returning to barely detectable levels at 3 and 7 days. Müller cell GFAP immunoreactivity was elevated by 24 hr, stronger by 48 hr and persisted for 30-45 days. Thus, the expression of GFAP immunoreactivity after photocoagulation was due to new protein synthesis but the mRNA, and therefore the stimulus, was only present for a few days. This indicates that the GFAP protein in Müller cells has a long lifetime similar to that of astrocytes despite different gene control elements. bFGF is a possible stimulus for Müller GFAP expression because Müller cells have bFGF receptors. bFGF mRNA was detectable in normal, 24 and 48 hr retinas but decreased to undetectable levels (even after 35 cycles of PCR) at three days after injury and had only partly recovered by 7 days. Immunocytochemistry demonstrated a rapid change in localization of bFGF at the lesion sites early after lesion. At 2-3 days bFGF in blood vessels was markedly increased while at 7 days there was an increase around the photoreceptors flanking each lesion. These shifts in bFGF localization were too late to be a stimulus for the widespread upregulation of GFAP expression by Müller cells. The reduction in bFGF mRNA at three days was unexpected as studies of brain injury generally show a longer lasting elevation of bFGF expression. Therefore it is likely that bFGF expression is controlled by different mechanisms in the retina compared to the brain. However, a reduction in bFGF synthesis after photocoagulation is consistent with the anti-angiogenic effect of laser photocoagulation in diabetic retinopathy.

Impaired endothelium-dependent relaxation after cardiac global ischemia and reperfusion: role of warm blood cardioplegia

OBJECTIVES

Experiments were designed to determine whether coronary endothelial dysfunction after cardiac global ischemia and reperfusion could be prevented by warm blood cardioplegic solution.

BACKGROUND

The coronary endothelium produces endothelium-derived relaxing factor (EDRF) to prevent vasospasm and thrombosis. After ischemia and reperfusion, endothelium-dependent relaxation (EDR) is diminished as a result of G-protein dysfunction.

METHODS

Dogs were exposed to extracorporeal circulation in 37 degrees C (group 1) or 28 degrees C (groups 2 and 3). The heart was ischemic for 120 min while continuous warm blood cardioplegic solution (group 1) or intermittent cold (4 degrees C) crystalloid cardioplegic solution was not used in group 3 animals. The heart was then allowed to function for 60 min of reperfusion.

RESULTS

Endothelium-derived relaxation in response to acetylcholine, adenosine diphosphate and sodium fluoride of the coronary rings of group 1 was significantly different from that of groups 2 and 3 but was not significantly different from that of group 4. In contrast, EDR in response to the receptor-independent calcium ionophore agonist A23187 was not significantly different between the four groups. Scanning electron microscopic studies showed that platelet adhesion and aggregation, area of microthrombi, disruption of endothelial cells and separation of the intercellular junction could be found in coronary segments of groups 2 and 3 but not in vessels of groups 1 and 4.

CONCLUSIONS

These experiments suggest that cardiac global ischemia and reperfusion impair receptor-mediated release of EDRF from the coronary endothelium with G-protein dysfunction. This type of coronary endothelial dysfunction can be prevented by continuous anterograde infusion of warm blood cardioplegic solution during global ischemia.

[Study on the immunophenotype of myeloid cells in myelodysplastic syndromes and its clinical implications]

OBJECTIVE

To explore the immunophenotype of myeloid cells in myelodysplastic syndromes and its clinical implications.

METHODS

A panel of monoclonal antibodies was used to detect CD13, CD33, CD15 and CD14 on the membrane surfaces of myeloid cells in the bone marrow from 51 patients with myelodysplastic syndromes (MDS), 21 with aplastic anemia (AA), 21 with paroxysmal nocturnal hemoglobinuria (PNH), and 15 normal subjects, by immunoenzymatic assay. The morphology and chromosome karyotype of bone marrow cells of MDS patients were also examined.

RESULTS

CD14+ cells, CD13+ cells and CD33+ cells in the bone marrow were more in MDS patients than in normal controls, AA patients and PNH patients. CD15+ cells in the bone marrow were less in MDS patients than in normal controls. The percentages of CD14, CD13 and CD33 positive cells in the bone marrow of MDS patients were related to the percentage of myeloblast, the chromosomal aberrations and the response to treatment.

CONCLUSION

There was an immunophenotypic misexpression of myeloid cells in MDS patients. Immunophenotype analysis of myeloid cells might be useful for the diagnosis and directing treatment in MDS patients.

[Effects of AT-I on murine cytokins productions and NK cell activity in vivo]

Antitumor-I (AT-I) is a traditional Chinese medicine, which known to be combined with chemotherapeutic agent on antitumor effects. In this paper, the effections of AT-I on interleukin-2 (IL-2) and interleukin-6 (IL-6) was detected and NK cell activity were observed in normal and tumor-bearing BALB/c mice in vivo. The results showed that AT-I could enhance IL-2 and IL-6 production in normal mice, and IL-2 product in tumor-bearing mice. The results suggest that AT-I at a appropriate dose could modulate immunofunctions, so known as a biological response modifier (BRM).

Vascular expression of inducible nitric oxide synthase is associated with activation of Ca(++)-dependent K+ channels

We tested the hypothesis that expression of inducible nitric oxide synthase (NO-synthase) in response to endotoxin (lipopolysaccharide) produces activation of potassium channels. Contraction of the rat thoracic aorta in response to phenylephrine was measured in vitro after treatment in vivo for 15 hr with vehicle (control) or lipopolysaccharide (10 mg/kg i.p.). Impaired contraction in response to phenylephrine was used as an index of inducible NO-synthase expression, and activation of potassium channels was examined with specific inhibitors. Contraction in response to 10(-5) M phenylephrine (expressed as a percentage of contraction in response to 85 mM KCI) was markedly impaired in lipopolysaccharide-treated rats, compared with control (15 +/- 5% vs. 131 +/- 10%, P < .05, mean +/- S.E.). Expression of inducible NO-synthase mRNA in the vessel wall in lipopolysaccharide-treated rats was confirmed using reverse transcription-polymerase chain reaction. Contraction of the aorta in lipopolysaccharide-treated rats was restored to normal by 0.3 mM aminoguanidine (an inhibitor of inducible NO-synthase). Contraction of the aorta in response to phenylephrine, which was inhibited by lipopolysaccharide, was not affected by glibenclamide (an inhibitor of ATP-sensitive potassium channels) but was increased 2-fold (P < .05) by iberiotoxin (50 nM), an inhibitor of Ca(+2)-dependent potassium channels. Relaxation of the aorta in response to sodium nitroprusside, an exogenous donor of nitric oxide, and 8-bromo-cyclic GMP was also inhibited by iberiotoxin. These findings suggest that nitric oxide produced by vascular expression of inducible NO-synthase activates calcium-dependent potassium channels and that this mechanism may contribute to impaired vasoconstrictor responses during sepsis.

Effect of activation of protein phosphatase 1 on sulfhydryl reactivity

Myofibril protein phosphatase 1 (PP1) from bovine heart, identified as PP1alpha, was purified in a latent form which was dependent on Co2+ or Mn2+ for activity (Y. Chu, S. E. Wilson, and K. K. Schlender (1994) Biochim. Biophys. Acta 1208, 45-54). This was also true for recombinant PP1 alpha expressed in Escherichia coli (Z. Zhang, G. Bai, S. Deans-Zirattu, M. F. Browner, and E. Y. C. Lee (1992) J. Biol. Chem. 267, 1484-1490). Here we report on the change in the sulfhydryl reactivity during the cation activation process. The activation of myofibrillar PP1 by Co2+ was prevented by 10 mM dithiothreitol (DTT) and incubation of the Co2+-activated enzyme with 50 mM DTT reversed the activation. Activation of recombinant PP1alpha was associated with 57Co2+ incorporation into PP1. DTT reversal of Co2+-activated PP1 was accompanied by release of Co2+ from the enzyme. The latent PP1 modified with 2-nitro-5-thiocyanobenzoic acid (NTCB) or N-ethylmaleimide (NEM) did not bind Co2+ and could not be activated by Co2+. Conversely, the Co2+-activated PP1 was resistant to inactivation with NTCB and less sensitive to NEM. Similarly, PP1 pretreated with NTCB was not activated by Mn2+ and the Mn2+-activated enzyme was also resistant to NTCB inhibition. The number of sulfhydryls of nondenatured PP1, reactive with 5, 5'-dithiobis[2-nitrobenzoic acid] (DTNB), was reduced from approximately 8 to 2-3 mol/mol when the enzyme was activated with Co2+ or Mn2+. After denaturation with guanidine-HCl, the number of reactive sulfhydryls of nonactivated PP1 and Co2+-activated PP1 was approximately 10 mol/mol enzyme. These results suggest that when PP1 is activated by Co2+ or Mn2+, the enzyme undergoes a conformational change resulting in some of the cysteine sulfhydryls no longer being accessible to chemical modification.

[Effects of AEA-I on murine IL-2 and IL-6 activities in vivo]

Antitumor-I (AT-I) is known as an effective traditional Chinese medicine to be used in combination with chemotherapeutic agents against tumor. It was demonstrated that AT-I could inhibit tumor growth and modulate IL-2, IL-6 and NK cell activities. In order to improve its preparation, we got the alcohol extract from AT-I (AEA-I) by using natural pharmaceutical alcohol extract method, and compared the effect of AEA-I on cytokins with that of AT-I. The results show that AEA-I has a good positive correlation with AT-I on IL-2 and IL-6 activities of mice in vivo.

[Experience with reoperation on mitral valve prostheses]

Heart valve replacement after closed mitral commissurotomy and mitral valve replacement with bioprostheses may result in complication and higher mortality and morbidity. Mitral valve replacement was performed in 32 cases after closed mitral commissurotomy and 12 cases after mitral valve replacement with bioprostheses from April 1986 to May 1994 in our hospital. The eraly mortality was 6.8% (3/42). The choice of operation and methods, myocardial preservation, measurement of heart resuscitation, and prevention of perioperative hemorrhage were discussed.

The mitogen-activated protein kinase phosphatases PAC1, MKP-1, and MKP-2 have unique substrate specificities and reduced activity in vivo toward the ERK2 sevenmaker mutation

Mitogen-activated protein (MAP) kinases can be grouped into three structural families, ERK, JNK, and p38, which are thought to carry out unique functions within cells. We demonstrate that ERK, JNK, and p38 are activated by distinct combinations of stimuli in T cells that simulate full or partial activation through the T cell receptor. These kinases are regulated by reversible phosphorylation on Tyr and Thr, and the dual specific phosphatases PAC1 and MKP-1 previously have been implicated in the in vivo inactivation of ERK or of ERK and JNK, respectively. Here we characterize a new MAP kinase phosphatase, MKP-2, that is induced in human peripheral blood T cells with phorbol 12-myristate 13-acetate and is expressed in a variety of nonhematopoietic tissues as well. We show that the in vivo substrate specificities of individual phosphatases are unique. PAC1, MKP-2, and MKP-1 recognize ERK and p38, ERK and JNK, and ERK, p38, and JNK, respectively. Thus, individual MAP kinase phosphatases can differentially regulate the potential for cross-talk between the various MAP kinase pathways. A hyperactive allele of ERK2 (D319N), analogous to the Drosophila sevenmaker gain-of-function mutation, has significantly reduced sensitivity to all three MAP kinase phosphatases in vivo.

Activation of protein phosphatase 1. Formation of a metalloenzyme

The recombinant catalytic subunit of protein phosphatase 1 is produced as an inactive enzyme which can be activated by Mn2+ (Zhang, Z., Bai, G., Deans-Zirattu, S., Browner, M. F., and Lee, E. Y. C. (1992) J. Biol. Chem. 267, 1484-1490). In this report, we have investigated the effects of divalent cations on the activity of recombinant catalytic subunit of protein phosphatase 1. Latent phosphatase 1 can be activated by Co2+ or Mn2+, whereas other metal ions tested including Fe2+, Zn2+, Mg2+, Ca2+, Cu2+, or Ni2+ were not effective or were only weakly effective in activating the enzyme. The Mn(2+)-stimulated activity was susceptible to inactivation by EDTA; however, the Co(2+)-activated phosphatase was stable after dilution and chelation of the Co2+ with excess EDTA. After stable activation of phosphatase 1 using 57Co2+, a stoichiometric amount of 57Co2+ was shown to be tightly bound to phosphatase 1. These findings demonstrate for the first time the generation of a stable metalloenzyme form of phosphatase 1. Fe2+ reversibly deactivated the Co(2+)-stimulated activity, but did not displace the bound Co2+. Interestingly, treatment of the enzyme with a combination of Fe2+ and Zn2+ (but not the individual metal ions) significantly activated phosphatase 1. These results suggest that at least two metal binding sites exist on the enzyme and that protein phosphatase 1 may be an iron/zinc metalloprotein in vivo.