[Role of kallikrein kinin system activation in kidney injury induced by trichloroethylene sensitized mice].

OBJECTIVE: Through testing the expression of complement C3 fragment C3b and iC3b, C5b-9 as well as indexes of KKS before and after using kallikrein-kinin system inhibitor PKSI-527, observing the relevant between KKS and complement system, we preliminary study on the mechanism how KKS works on the renal injury of sensitized mice model induced by trichloroethylene. METHODS: Female BALB/c mice (6~8 weeks) were randomly divided into blank control group (5), TCE treated group (15), PKSI-527+TCE treated group (15). Mice were sensitized with TCE in the 1,3,7,10 days, the first and the last challenge were on day 17 and 19. 24h before every challenge, mice in PKSI-527+TCE group were treated with intraperitoneal injection of KKS inhibitor PKSI-527 inhibitor (50mg/kg). Mice were killed 72h after the last challenge. The function of kidney in mice were detected and kidney B1R, B2R expression were detected using real-time quantitative PCR, mice kidney complement C3 fragments C3b, iC3b and C5b-9 deposition were also detected by chemoimmunology. RESULTS: Compared with blank control group, all indexes expressions in the solvent control group have no significant change. Compared with the solvent control group, BUN、Cr level and B1R、B2R level have an significant increase (P< 0.05) in TCE sensitized group and PKSI-527+TCE sensitized group; There is a sharp decrease in PKSI-527+TCE sensitized group compared to TCE sensitized group(P< 0.05). CONCLUSION: The renal damage in the TCE sensitization mouse model may aggravated by upregulate complement system followed by the activation of kallikrein-kinin system.

[Study on the expression of bradykinin and its receptors B1R and B2R in the kidney immune injury in trichloroethylene-sensitized mouse].

OBJECTIVE: To study the expression of bradykinin and its receptors B1R and B2R in the kidney immune injury in trichloroethylene-sensitized mouse and discuss the pathogenesis of Dermatitis Medicamentosa-like of TCE (ODMLT). METHODS: On the first days, intradermal injection by 50% TCE and the amount of FCA mixture 100 µl for initial sensitization; on 4, 7, 10 days, painted abdominal skin by 100 µl 50% TCE for three sensitization, on 17, 19 days, painted on the back skin by 100 µl 30% TCE for initial excitation and the last challenge; 24 h before each challenge, PKSI-527+TCE group received intraperitoneal injection by inhibitor PKSI-527 (50 mg/kg); solvent control group treat without TCE and sensitization and excitation reagent the same proportion of olive oil and acetone mixture, blank control group without any treatment. Before killing the mouse, renal weight and body weight were recorded. The renals and plasma were separated at 24 h, 48 h, 72 h and 7 d after the last challenge and observed pathological of the renals. Expression of B1R and B2R in renal were examined by immunofluorescence technique. Plasma were examined by ELISA for BK. RESULTS: The renal pathological examination revealed the apparent damage of TCE sensitized mice which compared to solvent control group showed obvious cellular infiltration, vacuolar degeneration of renal tubular epithelial cells. The renal damage of PKSI-527+TCE-sensitized groups which compared to the corresponding point of TCE-sensitized groups showed significantly reduced. The expression of BK in 24 h, 48 h and 72 h TCE-sensitized groups were significant higher than solvent control group and related TCE non-sensitized groups (P < 0.05) and 72 h point compared to the corresponding point of PKSI-527+TCE group was also increased, the difference was statistically significant (P < 0.05). The expression levels of B1R and B2R in the kidney in 24 h, 48 h, 72 h and 7 d TCE-sensitized groups were obviously higher than solvent control group and related TCE non-sensitized groups. The expression levels of B1R and B2R in the kidney in the four point of PKSI-527+TCE sensitized group were relatively lower than the corresponding point of TCE sensitized group. CONCLUSION: KKS activation may involved in the renal immune injury of trichloroethylene-sensitized mouse and the expression change of bradykinin and its receptors B1R and B2R which may play an important role in the process.

Computationally designed ß-turn foldamers of γ-peptides based on 2-(aminomethyl)cyclohexanecarboxylic acid.

The γ-peptide ß-turn structures have been designed computationally by the combination of chirospecific γ(2),(3)-residues of 2-(aminomethyl)cyclohexanecarboxylic acid (γAmc(6)) with a cyclohexyl constraint on the C(α) -C(ß) bond using density functional methods in water. The chirospecific γAmc(6) dipeptide with the (2S,3S)-(2R,3R) configurations forms a stable turn structure in water, resembling a type II' turn of α-peptides, which can be used as a ß-turn motif in ß-hairpins of Ala-based α-peptides. The γAmc(6) dipeptide with homochiral (2S,3S)-(2S,3S) configurations but different cyclohexyl puckerings shows the capability to be incorporated into one of two ß-turn motifs of gramicidin S. The overall structure of this gramicidin S analogue is quite similar to the native gramicidin S with the same patterns and geometries of hydrogen bonds. Our calculated results and the recently observed results may imply the wider applicability of chirospecific γ-peptides with a cyclohexyl constraint on the backbone to form various peptide foldamers.

Predicting subsite interactions of plasmin with substrates and inhibitors through computational docking analysis.

Plasmin plays important roles in various physiological systems. The identification of inhibitors controlling its regulation represents a promising drug-discovery challenge. To develop selective inhibitors of plasmin, structural information of the binding modes is crucial. Here, a computational docking study was conducted to provide structural insight into plasmin subsite interactions with substrates/inhibitors. Predicted binding modes of two peptide-substrates (D/L-Ile-Phe-Lys), and potent and weak inhibitors (YO-2 and PKSI-527) suggested non-prime and prime subsite interactions relevant to recognition by plasmin. Predicted binding modes also correlated well with the experimental structure-activity relationships for plasmin substrates/inhibitors, namely the differences of K(M) values between the D- and L-peptide-substrates and inhibitory potencies of YO-2 and PKSI-527. In particular, interaction observed at a hydrophobic pocket near S2 and at a tunnel-shaped hydrophobic S1' was strongly suggested to be significantly involved in tight binding of inhibitors to plasmin. Our present findings may aid in the design of potent and selective plasmin inhibitors.

Release of proteolytic activity following reduction in therapeutic human serum albumin containing products: detection with a new neoepitope endopeptidase immunoassay.

Botulinum type A toxin (BoNT/A) is defined by its specific endopeptidase cleavage of SNAP25 between Gln(197) and Arg(198) under reducing conditions. The neurotoxin is widely used for therapeutic or cosmetic purposes, but should not contain other toxin serotypes or unwanted protease activities. Using a neoepitope endopeptidase immunoassay, additional cleavage between Arg(198) and Ala(199) was detected with a range of therapeutic BoNT/A products confirming an earlier report of an unidentified proteolytic component. By developing the assay and making it insensitive to BoNT/C1, any activity due to the type C1 toxin was excluded. Therapeutic preparations consist of ng quantities of toxin protein which are typically stabilised by 0.125-30 mg of HSA. An excellent correlation (R(2)=0.993) between HSA content per vial and measured activity was obtained within the therapeutic BoNT/A products tested. No activity was detected in any of the non-albumin formulated preparations, thereby identifying HSA as the source of the unknown protease for the first time. To investigate the cause of this activity, either as an intrinsic molecular activity of albumin or due to an albumin-associated purification contaminant, further studies on a variety of commercial plasma-derived HSA products or recombinant HSA materials free from potential plasma contaminants were carried out. The measured proteolytic levels were highly consistent amongst preparations, and could all be partially inhibited by the presence of zinc and blocked by PKSI-527 and aprotinin. By contrast, the data did not support the role of plasmin, kallikrein, trypsin, α(2)-antiplasmin-plasmin complexes or HSA purification contaminants, PKA (prekallikrein activator) or kallikrein-like activity. Taken together, these findings indicate a new intrinsic proteolytic activity of the albumin molecule revealed under reducing conditions as the source of the unexpected Arg-Ala cleaving activity.

Angiotensin II type 2 receptor-mediated inhibition of norepinephrine release in isolated rat hearts.

We investigated whether endogenous and exogenous angiotensin II (Ang II) regulates norepinephrine (NE) release from cardiac sympathetic nerves via both Ang II type 2 receptors (AT2Rs) and Ang II type 1 receptors (AT1Rs). Using isolated rat hearts, sympathetic nerves were electrically stimulated. Ang II with PD-123319 (AT2R antagonist) but not Ang II alone produced a significant increase in nerve stimulation-induced NE overflow, which was abolished by the addition of AT1R antagonist losartan. In contrast, NE overflow was markedly decreased by losartan with or without Ang II. This decrease was abolished by the combination with PD-123319, nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine (NOARG), icatibant (bradykinin B2 receptor antagonist), or PKSI-527 (kininogenase inhibitor). CGP-42112A (AT2R agonist) suppressed nerve stimulation-induced NE overflow in the same way as the combination of Ang II and losartan, and this suppression was abolished by PD-123319, NOARG, icatibant, or PKSI-527. There were significant increases in NOx (NO2/NO3) contents in coronary effluent under conditions where NE overflow was suppressed. Ang II seems to function as an inhibitory modulator of cardiac noradrenergic neurotransmission via AT2Rs and well-known AT1R-mediated stimulatory actions. The inhibitory mechanism may involve local bradykinin production, its B2 receptor activation, and NO as a downstream effector.

Are gastroprotective drugs useful for gastric ulcer healing: re-evaluation using current ICH E9 guidelines.

Most of the gastroprotective drugs which had been marketed in Japan were considered to have insufficient rationale for use as ulcer treatments. Such drugs may have a crucial role in maintaining mucosal integrity by the mechanisms other than inhibition of acid secretion. We re-evaluated the effect of gastroprotective drugs on gastric ulcer healing using current ICH E9 guidelines. We collected reports of pivotal trials on healing rate of gastric ulcer with 9 kinds of gastroprotective drugs submitted in New Drug Applications. In the comparative trial of cetraxate vs. placebo, the healing rate of gastric ulcer at 8-week endoscopy in the cetraxate was significantly higher than that in the placebo groups (88.6% and 62.2%, p = 0.0062). Non-inferiority to cetraxate was confirmed for 8 kinds of gastroprotective drugs. In conclusion, the superiority of cetraxate over placebo and non-inferiority to cetraxate for 7 drugs was established in the respect of effect on ulcer healing.

Comparison of the effects of cytoprotective drugs on human plasma adrenocorticotropic hormone and cortisol levels with continual stress exposure.

Cetraxate hydrochloride (cetraxate), ecabet sodium (ecabet), and sulpiride, which are cytoprotective drugs, have been used to treat peptic ulcers and acute or chronic gastritis. They are reported to improve mucosal blood flow in the stomach. One of the most important factors believed to cause gastric ulcers is mental and/or physiological stress. When people feel stress, the hypothalamo-pituitary-adrenal (HPA) axis is activated. Therefore, corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and cortisol can be indicators of stress. We examined the effects of cetraxate, ecabet and sulpiride on the plasma levels of ACTH and cortisol under stress conditions by repetitive blood sampling. Venous blood samples were taken before and 20-240 min after a single administration of the drugs or a placebo. A single dose of ecabet caused significant suppression of increases in plasma ACTH-like immunoreactive substance (IS) levels at 90 to 120 min and cortisol levels at 240 min, compared with the response to placebo. Sulpiride only suppressed increases in plasma cortisol levels at 180 to 240 min, compared with the response to placebo. A single dose of cetraxate had no effect on plasma ACTH-IS and cortisol levels. Ecabet may have a modulatory effect on the HPA axis while sulpiride may have a partial modulatory effect on the HPA axis. These effects might be beneficial in stress-related disease.

Synergistic antithrombotic effect of a combination of NO donor and plasma kallikrein inhibitor.

The aim of the present study was to investigate the effect of a NO donor (GSNO) and a plasma kallikrein inhibitor (PKSI-527) alone and in combination on global haemostatic status. A new in vitro test was employed which allows the measurement of both platelet function and spontaneous thrombolysis. Sixteen healthy young and 18 elderly volunteers were enrolled in this study. When GSNO (1 mM) or PKSI-527 (20 microM) was added to native human blood, platelet reactivity was significantly inhibited in both age groups. The combination of GSNO and PKSI-527 had additive inhibitory effect on platelets. Addition of either GSNO or PKSI-527 to blood samples did not significantly affect spontaneous thrombolysis, while added together, spontaneous thrombolysis was significantly enhanced. The thrombolysis enhancing effect was more prominent in elderly subjects. Our present findings suggest that the combination of NO donor and plasma kallikrein inhibitor may have clinical antithrombotic potential.

Efficacy of triple therapy plus cetraxate for the Helicobacter pylori eradication in partial gastrectomy patients.

In the present study, we aimed to establish an additional standardized protocol with a higher H. pylori eradication rate in the remnant stomach. Fifty-five H. pylori-positive patients were randomly allocated to one of three regimens: LAC--lansoprazole, amoxicillin, and clarithromycin b.i.d. for 7 days (n = 17); LAC+CET--LAC b.i.d. plus cetraxate q.i.d. for 7 days (n = 20); and LEFT--LAC for 7 days in a horizontal body position on the left side for 30 min (n = 18). Patient compliance and side effects were checked via interviews. H. pylori eradication was successful in 75, 72, and 41% in LAC+CET, LEFT, and LAC, respectively. The eradication rate was significantly higher in LAC+CET than in LAC (P = 0.024) but not in LEFT (P = 0.058). Adverse events that occurred in each group were almost all mild ones. Cetraxate plus LAC for 1 week is a safe and effective regime for the eradication of H. pylori in patients after partial gastrectomy.

Biodegradable derivatives of tranexamic acid as transdermal permeation enhancers.

The purpose of this work was to develop a novel approach to transdermal permeation enhancer design, based on utilizing some favorable properties of their metabolites. As an example of this concept, a series of carbamic acid salts of tranexamic acid (TXA) esters was synthesized, because TXA was previously shown to improve skin barrier homeostasis. Enhancement activities of 1% TXA derivatives dispersed in both hydrophilic and lipophilic vehicles were evaluated in vitro using human skin and theophylline as a model drug. Dispersed in an aqueous donor vehicle, the dodecyl ester showed the enhancement ratio (ER) of 4.3+/-0.9, which is almost 2 times higher than that of 1-dodecylazepan-2-one (Azone; 2.2+/-0.7). From an isopropyl-myristate suspension, the decyl ester was the most effective enhancer (4.9+/-1.4), while Azone was inactive. Decomposition of the carbamate in a slightly acidic environment was shown by FTIR; hydrolysis of the pertinent ester by porcine esterase was monitored by TLC and HPLC. Biodegradable enhancers of this type could mediate easier and faster recovery of the skin barrier after transdermal delivery through the action of the released TXA.

DA-9601 for erosive gastritis: results of a double-blind placebo-controlled phase III clinical trial.

AIM: To determine the efficacy and safety of DA-9601 on erosive gastritis versus cetraxate as a standard drug by gastrointestinal endoscopy. METHODS: Five hundred and twelve patients with erosive gastritis were divided into three groups. The groups received 180 mg or 360 mg of DA-9601, or 600 mg of cetraxate (Neuer) t.i.d. for 2 wk, respectively. Endoscopic observations were performed before and 2 wk after the treatment, and the cure and improvement rates were investigated. RESULTS: Of the 512 intention-to-treat (ITT) population, 457 patients comprised the per protocol (PP) analysis. Endoscopic cure rate was significantly higher in the DA-9601 group than in the cetraxate group in both the PP (56%, 58% vs 36%; DA-9601 180 mg, 360 mg and cetraxate, respectively) and ITT (52%, 51% vs 35%) populations. Two DA-9601 groups (180 and 360 mg) had significantly higher endoscopic improvement rates than the cetraxate group in both the PP (67%, 65% vs 46%) and ITT (63%, 58% vs 45%) populations. The percentage of symptom relief over the 2 wk was found not significantly different between groups. During the study, both DA-9601 and cetraxate produced no treatment-associated adverse events. CONCLUSION: From these results, it appears that DA-9601 has excellent efficacy on erosive gastritis. This study also confirms the safety profile of DA-9601.

Comparison of cetraxate-based and pantoprazole-based triple therapies in the treatment of Helicobacter pylori infection.

BACKGROUND: Recent studies suggest that cetraxate possesses anti-Helicobacter pylori (H. pylori) activity. We therefore conducted this pilot study to investigate the efficacy of a cetraxate-based triple therapy and to compare the regimen with proton pump inhibitor-based triple therapy. METHODS: From April 2001 to January 2002, a total of 58 H. pylori-infected patients were randomly assigned to 1 of 2 regimens for 1 week: cetraxate plus clarithromycin and amoxicillin (CCA group) or pantoprazole plus clarithromycin and amoxicillin (PCA group). Follow-up endoscopy was performed at 8 weeks after the end of treatment to assess the treatment response. RESULTS: Intention-to-treat analysis showed that the eradication rates of the CCA group (n = 27) and PCA group (n = 31) were 70.4% and 93.5%, respectively. The CCA group had a significantly lower eradication rate than the PCA group (p = 0.03). Per-protocol analysis also showed similar results (69.2% vs. 96.7%, p = 0.01). However, the frequency of adverse events in the CCA group was lower than that of the PCA group (3.7% vs. 25.8%, p = 0.03). Univariate analysis showed that the eradication rate was significantly related to proton pump inhibitor therapy (93.5% vs. 70.4%, p = 0.03 ) and smoking habit (66.7 % vs. 88.4%, p = 0.05), but multivariate analysis disclosed that proton pump inhibitor therapy was the only independent factor predicting treatment success (p < 0.05). CONCLUSIONS: Cetraxate-based triple therapy is less effective than pantoprazole-based triple therapy in the treatment of H. pylori infection. However, the former has a lower frequency of adverse effects than the latter.

Cetraxate raises levels of calcitonin gene-related peptide and substance P in human plasma.

Cetraxate hydrochloride (cetraxate), an anti-ulcer drug, produces a dose-related increase in mucosal blood flow. Recently, it was found that capsaicin-sensitive afferent nerves play an important role in gastric mucosal defence. Capsaicin stimulates afferent nerves and enhances the release of calcitonin gene-related peptide (CGRP) and substance P in the stomach. We studied the effect of cetraxate on human plasma CGRP and substance P in healthy subjects. Cetraxate (800 mg) or placebo were orally administered to five healthy males. Blood samples were taken before, and at 20, 40, 60, 90, 120, 180 and 240 min after administration, followed by the extracting procedure, and submitted to a highly sensitive enzyme immunoassay system for CGRP and substance P. Single administration of cetraxate caused significant increases in plasma CGRP concentration at 60-120 min compared with placebo. Cetraxate significantly increased plasma substance P levels at 40-90 min compared with placebo. In this study, we hypothesized that cetraxate might indirectly stimulate capsaicin-sensitive afferent nerves and increase mucosal blood flow, and that this may be a key mechanism underlying its gastroprotective action.

Suppression of argatroban-induced endogenous thrombolysis by PKSI-527, and antibodies to TPA and UPA, evaluated in a rat arterial thrombolysis model.

We have previously confirmed, using a rat mesenteric arteriole thrombolysis model, that thrombin inhibition induces endogenous thrombolysis in vivo. In addition, we have shown that thrombin-activatable fibrinolysis inhibitor (TAFI) plays a role in the down regulation of endogenous thrombolysis. However, the mechanism of endogenous thrombolysis or spontaneous plasmin generation in vivo remains unclear. It has been shown in an in vitro system that plasma kallikrein activates pro-urokinase (pro uPA) and/or plasminogen, resulting in plasmin generation. These findings suggest that spontaneous fibrinolysis might be mediated by tPA and plasma kallikrein-dependent uPA. The aim of the present study was to examine whether these mechanisms play a dominant role in endogenous thrombolysis in vivo, using our rat mesenteric arterial thrombolysis model. Argatroban infusion enhanced endogenous thrombolysis. PKSI-527, anti uPA and anti tPA IgGs suppressed argatroban-induced thrombolysis. Also, the antibody IgG preparations suppressed endogenous thrombolysis in the absence of argatroban. In the presence of PKSI-527, anti tPA IgG was more effective than anti uPA IgG in suppressing argatroban-induced thrombolysis. The results suggested that both tPA and plasma kallikrein-mediated uPA activation and tPA release contribute to endogenous fibrinolytic or thrombolytic mechanisms.

Biocatalytic deprotection of a cetraxate ester by Microbacterium sp. strain 7-1W cells.

Enzymatic deprotection of the terminal ester bond of a cetraxate methyl ester was done with resting cells of Microbacterium sp. strain 7-1W, which produces an esterase catalyzing a regioselective hydrolysis reaction, as the catalyst. When 20 g of cetraxate methyl ester in 50 ml of a reaction mixture was incubated with 5 g of wet cells for 17 h, 96% of the substrate was converted to the desired product, cetraxate, quantitatively.