Platelet-activating factor dilates efferent arterioles through glomerulus-derived nitric oxide

Despite evidence that platelet-activating factor (PAF) is produced by the glomerulus, its direct action on the glomerular microcirculation is poorly understood. It was recently reported that at picomolar concentrations, PAF dilates isolated microperfused afferent arterioles (Af-Art) via nitric oxide (NO). The present study tested the hypothesis that PAF acts on the glomerulus to release NO, which in turn controls the resistance of the efferent arteriole (Ef-Art). Rabbit Ef-Art were perfused from the distal end (retrograde perfusion [RP]) to eliminate the influence of the glomerulus, or through the glomerulus from the end of the Af-Art (orthograde perfusion [OP]) to maintain the influence of the glomerulus. Ef-Art were preconstricted by approximately 40% with norepinephrine and increasing doses of PAF were added to both the arteriolar perfusate and bath. Only with OP did PAF at picomolar concentrations cause significant dilation: at 400 pmol, the diameter increased by 64 +/- 11% from the preconstricted level (N = 6, P < 0.01). This dilation was completely abolished by pretreatment with an NO-synthesis inhibitor. To study its possible constrictor action, PAF was added to nonpreconstricted Ef-Art. At nanomolar concentrations, PAF constricted Ef-Art similarly in both RP and OP: at 40 nM, the diameter decreased by 24 +/- 4% (N = 6, P < 0.01) and 20 +/- 2% (N = 6, P < 0.01), respectively. This constriction was attenuated by pretreatment with indomethacin (Indo) in both RP (14 +/- 2%, N = 7; P < 0.02 versus without Indo) and OP (10 +/- 2%, N = 6; P < 0.02 versus without Indo).

IN CONCLUSION

(1) at picomolar concentrations, PAF stimulates the glomerulus to release NO, which in turn dilates the Ef-Art; and (2) at nanomolar concentrations, PAF constricts the Ef-Art partly through release of cyclooxygenase metabolites. Thus, PAF may play a role in glomerular hemodynamics under various physiological and pathological conditions.

Topology of prostaglandin H synthase-1 in the endoplasmic reticulum membrane

Prostaglandin H synthase-1 is an integral endoplasmic reticulum membrane protein which catalyzes a key control step in prostaglandin biosynthesis. The overall arrangement of the prostaglandin H synthase-1 polypeptide with respect to the endoplasmic reticulum membrane was examined in transiently transfected COS-1 cells, using immunofluorescence microscopy. A bacterial toxin, streptolysin-O, was used for selective plasma membrane permeabilization and a detergent, saponin, for general membrane permeabilization. Treated cells were probed with six antibodies specific for particular prostaglandin H synthase-1 peptide segments and one antibody specific for an inserted viral reporter epitope. Control experiments established that actin, a cytoplasmic marker, was accessible to fluorescein-labeled phalloidin after streptolysin-O treatment, whereas antibodies against protein disulfide isomerase, an endoplasmic reticulum lumenal marker, bound only after saponin treatment, Using this approach to investigate prostaglandin H synthase-1, it was found that streptolysin-O treatment was sufficient to obtain staining of intracellular membranes by antibodies specific for the endogenous C-terminal segment, for the viral reporter inserted at the C-terminus, and for the protease-sensitive region near arg277. In contrast, saponin treatment was necessary for staining by antibodies specific for peptides spanning residues 51-66, 156-170, and 377-390. Antibodies targeted against residues 483-496 did not stain transfected cells even after saponin permeabilization, although they did bind to detergent-solubilized prostaglandin H synthase-1. These results indicate that the C-terminus and arg277 regions of the synthase can be exposed on the cytoplasmic side of the endoplasmic reticulum membrane, whereas regions near N-glycosylation sites are confined to the endoplasmic reticulum lumen and residues 483-496 are inaccessible from either side of the endoplasmic reticulum membrane.

Mechanism of metallothionein gene regulation by heme-hemopexin. Roles of protein kinase C, reactive oxygen species, and cis-acting elements

Heme-hemopexin or cobalt protoporphyrin (CoPP)-hemopexin (a model ligand for hemopexin receptor occupancy) is shown to increase transcription of the metallothionein-1 (MT-1) gene by activation of a signaling pathway. Promoter deletion analysis followed by transient transfection assays show that 110 base pairs (-153 to -43) of 5'-flanking region of the murine MT-1 promoter are sufficient for increasing transcription in response to heme-hemopexin or to CoPP-hemopexin in mouse hepatoma cells. The protein kinase C inhibitor, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H7), prevented the increase in MT-1 transcription by heme-hemopexin, CoPP-hemopexin, or phorbol 12-myristate 13-acetate, but the protein kinase A inhibitor, HA1004, was without effect. N-Acetylcysteine (NAC) and glutathione, as well as superoxide dismutase and catalase, inhibited both the increase in endogenous MT-1 mRNA and the activation of reporter gene activity by heme-hemopexin, CoPP-hemopexin, and phorbol 12-myristate 13-acetate. In sum, these data suggest that reactive oxygen intermediates are generated by heme-hemopexin via events associated with receptor binding, including protein kinase C activation. Induction of heme oxygenase-1 expression, in contrast to MT-1, is significantly less sensitive to NAC. Deletion and mutation analyses of the MT-1 proximal promoter revealed that the sequence 5'-GTGACTATGC-3' (from -98 to -89 base pairs) is, in part, responsible for the hemopexin-mediated regulation of MT-1 which is inhibited by H7. Regulation via this element is also induced by H2O2 showing that it is an antioxidant response element. Heme itself acts via more distal elements on the MT-1 promoter. In contrast to NAC and glutathione, diethyl dithiocarbamate and pyrrolidine dithiocarbamate, which inactivate reactive oxygen intermediates and chelate Zn(II), synergistically augment the induction of MT-1 mRNA levels and reporter gene activity in response to heme-hemopexin via the antioxidant response element by both metal-responsive element-dependent and -independent mechanisms.

[Evaluation of operative corrigent degree of scoliosis by improved Cobb's angle degree of preoperative suspensive roentgenogram]

To achieve best operative result in correction of scoliosis, and avoid complications of the nerve system due to excess correction, we compared the statistical results of modified Cobb's degree of preoperative suspensive roentgenogram and operative corrigent degrees of 331 patients with scoliosis, including 219 with idiopathic scoliosis. The modified Cobb's degrees of the whole group was 20.15 +/- 9.41 in suspension, the operative corrigent degree was 35.34 +/- 13.05, and the operation-suspension difference was 14.62 +/- 11.02. Referring to idiopathic scoliosis, it was 21.79 +/- 8.39, 37.44 +/- 11.82, 15.58 +/- 9.91 respectively. And the statistacal study was performed according to scoliosis type, involved segments, curvature degree, and ages. The parameters were very helpful in the evaluation of currigent effect before operation.

A rifampicin-induced hepatic microsomal enzyme system for the generation of cyclosporine metabolites

A drug-induced rabbit hepatic microsomal enzyme system has been developed to produce milligram quantities of cyclosporine metabolites (CMs). Using a rifampicin-induced microsomal preparation in the presence of a NADPH regenerating system, 60% of the cyclosporine (CsA) was converted to CMs in 2 h. The CMs were recovered by solid phase extraction, and separated by gradient high performance liquid chromatography with two Ultrasphere Ocyl (C8) columns connected in tandem. More than 20 CMs were resolved. The quantities of major CMs produced by 45 mg of microsomal proteins were established by comparing peak areas with known concentrations of authentic CM standards. These major CMs included AM1, AM9, AM19, AM4N, AM1c and the aldehydic isomers (AM1cAL plus AM1AL). Other CMs that were not quantified included AM14N, AM4N9, AM1A, AM1c9, and AM1D1. Several CMs remained to be identified. All CMs were detected by radioimmunoassay using a non-specific CsA antiserum. The purity of the CMs were confirmed by fast atomic bombardment mass spectrometry. Similar findings were observed when erythromycin or trolandomycin was used to induce the hepatic microsomal enzymes. The procedure used to generate CMs was simple. With the enzyme fraction derived from one rabbit liver, 90 to 100 mg of CMs can be obtained. In this study, the metabolite patterns of CsA produced by rabbit liver microsomes were shown to resemble those observed for humans. These results indicate the possibility of using rabbit models to predict CsA biotransformation in man. The CMs generated by this enzyme system can be used to acquire information relevant to the situation in man.

[Study of anti-cerebral thromboembolism injection's activity on experimental arterial thrombosis and its therapeutical mechanism]

Anti-Cerebral Thromboembolism Injection (ACTI), applied intravenously in Cattaneo's animal model of arterial thrombosis, could significantly reduce the weight of thrombus, blood viscosities, plasma TXB2 level and delay the prothrombin time, compared to control group (P < 0.05). From this trial, it was indicated that ACTI's reducing thrombosis action was the result of inhibiting aggregation and releasing of platelets through reducing whole blood viscosities and TXB2 level.

[Effects of 3 kinds of decoction on serum gastrin, gastrin cell density and the content of PGE2 of gastric antral mucosa in experimental chronic gastritis in rats]

Experimental chronic gastritis (ECG) models were established in rats by inserting a spring into pyloric canal as well as feeding sodium deoxycholate. An experiment was undertaken to observe the therapeutic effects of three formulas of traditional Chinese medicine "Shipitong" (SPT), "Ganpingyangwei" (GPYW) and "Weile" (WL). The experimental results show that all of the three decoctions can make serum gastrin, gastrin cell density and amount of antral mucosal PGE2 of the ECG rats return to normal levels.

CD36 gene transfer confers capacity for phagocytosis of cells undergoing apoptosis

Phagocyte recognition and ingestion of intact cells undergoing apoptosis are key events in this generally important program of cell death. Insufficient phagocyte capacity for apoptotic cells can result in failure to clear dying cells before membrane integrity is lost, resulting in leakage of noxious cell contents and severe tissue damage. However, no means has been available to increase phagocytic clearance of apoptotic cells. We now report that transfection of the macrophage adhesion molecule CD36 into human Bowes melanoma cells specifically conferred greatly increased capacity to ingest apoptotic neutrophils, lymphocytes, and fibroblasts, comparable to that exhibited by macrophages. Furthermore, when CD36 was transfected into another cell type with limited capacity to take up apoptotic bodies, the monkey COS-7 cell, similar effects were observed. Therefore, CD36 gene transfer can confer "professional" capacity to ingest apoptotic cells upon "amateur" phagocytes.

[An experimental study on the integrated effects of heat-cleaning and detoxifying drugs and fire-purging drugs used in combination]

Heat-cleaning and detoxifying drugs and fire-purging drugs used in combination have been proved able to restore the endotoxin-induced deviant of HCT, blood viscositites, PTT and fibrinolytic activity, and reduce the blood content of both endotoxin and PGE2 in rabbits. In addition, the combination can also decrease the pes swelling percentage in rats as well as evans blue extravasation volume in mice. In practice, however, it should be noted that the bitter and cold qualities of these two kinds of drugs may be harmful to health.

The orphan receptor hepatic nuclear factor 4 functions as a transcriptional activator for tissue-specific and hypoxia-specific erythropoietin gene expression and is antagonized by EAR3/COUP-TF1

The erythropoietin (Epo) gene is regulated by hypoxia-inducible cis-acting elements in the promoter and in a 3' enhancer, both of which contain consensus hexanucleotide hormone receptor response elements which are important for function. A group of 11 orphan nuclear receptors, transcribed and translated in vitro, were screened by the electrophoretic mobility shift assay. Of these, hepatic nuclear factor 4 (HNF-4), TR2-11, ROR alpha 1, and EAR3/COUP-TF1 bound specifically to the response elements in the Epo promoter and enhancer and, except for ROR alpha 1, formed DNA-protein complexes that had mobilities similar to those observed in nuclear extracts of the Epo-producing cell line Hep3B. Moreover, both anti-HNF-4 and anti-COUP antibodies were able to supershift complexes in Hep3B nuclear extracts. Like Epo, HNF-4 is expressed in kidney, liver, and Hep3B cells but not in HeLa cells. Transfection of a plasmid expressing HNF-4 into HeLa cells enabled an eightfold increase in the hypoxic induction of a luciferase reporter construct which contains the minimal Epo enhancer and Epo promoter, provided that the nuclear hormone receptor consensus DNA elements in both the promoter and the enhancer were intact. The augmentation by HNF-4 in HeLa cells could be abrogated by cotransfection with HNF-4 delta C, which retains the DNA binding domain of HNF-4 but lacks the C-terminal activation domain. Moreover, the hypoxia-induced expression of the endogenous Epo gene was significantly inhibited in Hep3B cells stably transfected with HNF-4 delta C. On the other hand, cotransfection of EAR3/COUP-TF1 and the Epo reporter either with HNF-4 into HeLa cells or alone into Hep3B cells suppressed the hypoxia induction of the Epo reporter. These electrophoretic mobility shift assay and functional experiments indicate that HNF-4 plays a critical positive role in the tissue-specific and hypoxia-inducible expression of the Epo gene, whereas the COUP family has a negative modulatory role.

Proinflammatory cytokines potentiate thrombospondin-mediated phagocytosis of neutrophils undergoing apoptosis

Apoptosis leads to swift recognition, ingestion, and degradation of intact senescent neutrophils by macrophages. This protects tissues from leakage of noxious contents from dying cells and may promote resolution of inflammation. However, little has been known of the mechanisms that regulate macrophage capacity for apoptotic cells during an inflammatory response. We examined whether proinflammatory cytokines modulated phagocytosis of senescent neutrophils undergoing apoptosis by human monocyte-derived macrophages at 4 days maturity (4d M phi), an in vitro model of neutrophil "disposal" by apoptosis. Pretreatment of 4d M phi with granulocyte-macrophage-CSF increased the proportion of 4d M phi taking up apoptotic PMN in a concentration-dependent fashion by up to approximately 240%. This was by a rapid effect detectable by 4 h and exerted on the M phi, not the PMN. Granulocyte-macrophage-CSF also increased the number of apoptotic PMN taken up by each M phi. IFN-gamma, IL-1 beta, TNF-alpha, and TGF-beta 1 also enhanced phagocytosis, but IL-4 and IL-6 had no effect. In each case, the cytokine-expanded phagocytic subpopulation employed the thrombospondin (TSP)-dependent recognition mechanism defined for mature M phi, in which M phi vitronectin receptor and CD36 cooperate. However, commensurate increases in M phi expression of VnR, TSP, or CD36 were not detectable, indicating that TSP-mediated recognition can be recruited by other mechanisms. Cytokines did not recruit phosphatidylserine-dependent recognition, the other major mechanism by which some macrophage populations ingest apoptotic cells. Thus, M phi phagocytosis of apoptotic neutrophils can be potentiated by proinflammatory cytokines, suggesting a mechanism for negative feedback control of neutrophil number at inflamed sites.

Proinflammatory cytokines potentiate thrombospondin-mediated phagocytosis of neutrophils undergoing apoptosis

Apoptosis leads to swift recognition, ingestion, and degradation of intact senescent neutrophils by macrophages. This protects tissues from leakage of noxious contents from dying cells and may promote resolution of inflammation. However, little has been known of the mechanisms that regulate macrophage capacity for apoptotic cells during an inflammatory response. We examined whether proinflammatory cytokines modulated phagocytosis of senescent neutrophils undergoing apoptosis by human monocyte-derived macrophages at 4 days maturity (4d M phi), an in vitro model of neutrophil "disposal" by apoptosis. Pretreatment of 4d M phi with granulocyte-macrophage-CSF increased the proportion of 4d M phi taking up apoptotic PMN in a concentration-dependent fashion by up to approximately 240%. This was by a rapid effect detectable by 4 h and exerted on the M phi, not the PMN. Granulocyte-macrophage-CSF also increased the number of apoptotic PMN taken up by each M phi. IFN-gamma, IL-1 beta, TNF-alpha, and TGF-beta 1 also enhanced phagocytosis, but IL-4 and IL-6 had no effect. In each case, the cytokine-expanded phagocytic subpopulation employed the thrombospondin (TSP)-dependent recognition mechanism defined for mature M phi, in which M phi vitronectin receptor and CD36 cooperate. However, commensurate increases in M phi expression of VnR, TSP, or CD36 were not detectable, indicating that TSP-mediated recognition can be recruited by other mechanisms. Cytokines did not recruit phosphatidylserine-dependent recognition, the other major mechanism by which some macrophage populations ingest apoptotic cells. Thus, M phi phagocytosis of apoptotic neutrophils can be potentiated by proinflammatory cytokines, suggesting a mechanism for negative feedback control of neutrophil number at inflamed sites.

[The effects of progestin on the bone metabolism in postmenopausal women]

Thirty postmenopausal women, including 26 with history of hysterectomy and bilateral salpingooophorectomy due to uterine myoma and 4 with natural menopause without any diseases were randomly allocated into two groups. Fifteen subjects received medroxyprogesterone acetate (MPA) 10 mg twice daily for three months, the other 15 received both MPA 10 mg twice daily and cyclopentylethinyl estriol (CEE3) 5 mg once a month for three months. Fasting urinary calcium/creatinine (Ca/Cr) and hydroxyproline/creatinine (OHpr/Cr) ratio, serum calcitonon (CT) and alkaline phosphatase (AKP) concentrations were measured before and after treatment in all subjects. The results showed that in both groups, the fasting urinary Ca/Cr and OHpr/Cr ratio reduced significantly, while serum CT and AKP increased significantly after treatment. The changes of these parameters were not significantly different between these two groups. These data indicated that progestin alone appeared effective in preventing postmenopausal osteoporosis.

Prostaglandin H synthase-1: evaluation of C-terminus function

The first committed step in prostaglandin biosynthesis is catalyzed by prostaglandin H synthase, an enzyme localized to the endoplasmic reticulum (ER) membrane in a variety of cells. Several types of C-terminal region peptide sequence motifs have been found to lead to ER retention of other proteins. We have tested the potential role for such signals in the ER localization and catalytic activity of human isoform-1 of the synthase (PGHS-1). PGHS-1 mutants with alterations in the C-terminus designed to disrupt potential retention signals were expressed in transfected COS-1 cells. The mutations included: substitution of valine for the ultimate leucine residue (position 600) to disrupt a KDEL-type signal, substitution of a neutral glutamine for arginine at position 595 to disrupt signals based on positive charge, and deletion of the last six residues, to remove all of the wild-type extreme C-terminus. The subcellular localization of each recombinant PGHS-1 was assessed by differential centrifugation and by immunofluorescence microscopy. None of the mutations led to a significant change in the distribution of PGHS-1 between microsomes and other cellular fractions. Immunostaining of wild-type PGHS-1 and all of the mutants colocalized with that of protein disulfide isomerase, an ER marker protein. However, mutation of the terminal leucine or deletion of the last six residues did lead to loss of cyclooxygenase activity. Mutation of the terminal leucine also altered the pattern of fragments produced by limited proteolysis, indicating that this mutation led to changes in the polypeptide folding which might account for the loss of activity. The results indicate that the extreme C-terminal region is important to the functional integrity of PGHS-1, but it is not an essential part of the intracellular targeting mechanism.

[Experimental study on compatible application of heat-clearing and detoxifying drugs with blood circulation improving drugs]

The article describes the effectiveness of compatible application of heat-clearing and detoxifying drugs with blood circulation improving drugs to the animal model with endotoxemia and nonspecific inflammation. The compatible application reduces PGE2, endotoxin blood concentration and reduced viscosity of whole blood, decreases Evans blue extravasation volume and pes swelling percentage, increases serum cortisol content and enhances fibrinolytic activity. The experimental result shows that in most cases these two drugs work better when used in combination which implies that compatible application is more effective in detoxification, antiinflammation and inflammation recovery.

Epidural versus subcutaneous administration of alfentanil for the management of postoperative pain

This study was designed to compare the efficacy and serum concentrations of alfentanil given subcutaneously (SQ) or epidurally (EPID) for treatment of postoperative pain. Following abdominal surgery, patients (n = 12) were randomly assigned to receive double-blind SQ or EPID alfentanil over 24 h via the allocated route (1 mg along with 0.2 mg/h and 0.2-mg boluses on demand) and saline via the other route of administration using a patient-controlled analgesic (PCA) delivery system. Significantly less EPID alfentanil produced better quality analgesia and fewer side effects than SQ alfentanil. The fact that EPID analgesia was maintained with serum alfentanil concentrations less than those producing systemic analgesia confirms the spinal site of the EPID alfentanil action.

Overexpression and characterization of recombinant human fusion protein IL-6/IL-2 (CH925)

An expression vector encoding the human recombinant fusion protein interleukin 6/interleukin 2 (IL-6/IL-2) was constructed. When a flexible linker had been synthesized and ligated with the IL-2 gene fragment by polymerase chain reaction (PCR) amplification, the IL-6 gene fragment was unidirectionally inserted into the upstream of the linker-IL-2 sequence. The molecule of the IL-6-linker-IL-2 fusion gene named E. coli DH5 alpha/pfIL-6/2 was cloned and identified by DNA sequencing. The expressed protein named as CH925 showed a strong band on SDS-PAGE and amounted to 32% of total cell protein, and its estimated molecular weight was about 37 kDa. The fusion protein purified by gel filtration and reversed-phase HPLC showed as almost homogeneous. CH925 possesses both IL-2 and IL-6 activities when assayed by CTLL2- and 7TD1-dependent cell lines, respectively. The specific activity of IL-2 was 2.1 x 10(6) U/mg while that of IL-6 was 2.3 x 10(8) U/mg. Our studies exhibited that CH925 exerted a significant augmentative effect on the growth of erythroid colony forming units (CFU-E), and synergized with erythropoietin (EPO) and/or IL-3 in a dose-dependent way. Our experimental results also showed CH925 at a low dose causing active lymphokine-activated killer (LAK) cell proliferation more vigorous than IL-2 and/or IL-6 (p < 0.001). CH925 is a novel fusion protein, being neither IL-6 nor IL-2, more potent than IL-2 and/or IL-6 and causing non-IL-2 and non-IL-6 functions of strong EPO-like and mild IL-3-like effects on erythroid progenitor cell growth. There is a potential for efficacious clinical application of CH925.