The importance of brain PGE2 inhibition versus paw PGE2 inhibition as a mechanism for the separation of analgesic and antipyretic effects of lornoxicam in rats with paw inflammation.

OBJECTIVES: Lornoxicam is a non-selective cyclooxygenase inhibitor that exhibits strong analgesic and anti-inflammatory effects but a weak antipyretic effect in rat models. Our aim was to investigate the mechanism of separation of potencies or analgesic and antipyretic effects of lornoxicam in relation to its effect on prostaglandin E2 (PGE2) production in the inflammatory paw and the brain. METHODS: A model of acute or chronic paw inflammation was induced by Freund's complete adjuvant injection into the rat paw. Lornoxicam (0.01-1 mg/kg), celecoxib (0.3-30 mg/kg) or loxoprofen (0.3-30 mg/kg) was administered orally to the rats and the analgesic and antipyretic effects were compared. The paw hyperalgesia was assessed using the Randall-Selitto test or the flexion test. Dorsal subcutaneous body temperature was measured as indicator of pyresis. After the measurement of activities, the rats were sacrificed and the PGE2 content in the paw exudate, cerebrospinal fluid or brain hypothalamus was measured by enzyme-immunoassay. KEY FINDINGS: In a chronic model of arthritis, lornoxicam, celecoxib and loxoprofen reduced hyperalgesia with an effective dose that provides 50% inhibition (ED50) of 0.083, 3.9 and 4.3 mg/kg respectively, whereas the effective dose of these drugs in pyresis was 0.58, 0.31 and 0.71 mg/kg respectively. These drugs significantly reduced the PGE2 level in paw exudate and the cerebrospinal fluid. In acute oedematous rats, lornoxicam 0.16 mg/kg, celecoxib 4 mg/kg and loxoprofen 2.4 mg/kg significantly reduced hyperalgesia to a similar extent. On the other hand, lornoxicam did not affect the elevated body temperature, whereas celecoxib and loxoprofen significantly reduced the pyrexia to almost the normal level. These drugs significantly reduced the PGE2 level in inflamed paw exudate lo almost the normal level. On the other hand, lornoxicam did not change PGE2 level in the brain hypothalamus, whereas celecoxib and loxoprofen strongly decreased it. CONCLUSIONS: Lornoxicam exhibits strong analgesic but weak antipyretic effects in rats with paw inflammation. Such a separation of effects is related to its efficacy in the reduction of PGE2 levels in the paw and brain hypothalamus.

Continuous inhibition of 20-HETE synthesis by TS-011 improves neurological and functional outcomes after transient focal cerebral ischemia in rats.

TS-011, a potent and selective inhibitor of 20-HETE synthesis, has been described as providing significant benefits in animal stroke models. However, no studies have investigated changes in brain 20-HETE levels after cerebral ischemia. Also lacking are studies of TS-011 pharmacodynamics with respect to brain 20-HETE levels that may explain the benefits of TS-011 in animal models of ischemic stroke. The present study sought to explore changes in 20-HETE levels in brain tissue, as well as in plasma, after a 90-min episode of transient focal cerebral ischemia. Pharmacodynamics of TS-011 were also examined. Then, we evaluated the long-term effects of TS-011 when administered as in this pharmacodynamics study. The major findings of the present study are as follows: (1) brain 20-HETE levels increased significantly within 7.5h after MCAO; (2) TS-011 at doses of 0.1 and 0.3mg/kg administered at regular 6-h intervals appeared to reduce brain 20-HETE levels continuously; (3) TS-011 when administered as in this pharmacodynamics study improved long-term neurological and functional outcomes. These findings strongly suggest that 20-HETE plays an important role in the development of neurological and functional deficits after focal cerebral ischemia and that TS-011 may provide benefits in patients suffering ischemic stroke.

Putative mechanism of the itch-scratch circle: repeated scratching decreases the cutaneous level of prostaglandin D2, a mediator that inhibits itching.

In atopic dermatitis, scratching of the skin as a reaction to itching causes injury to the skin, which, in turn, further increases the itching resulting in the establishment of the so-called itch-scratch circle. We have shown that prostaglandin (PG) D2 plays an inhibitory role against pruritus in mice with atopic-like dermatitis; therefore, we examined the relationship between scratching and the cutaneous PGD2 level using an artificial scratching model with a wire brush. Mechanical scratching induced a temporary increase of the skin PGs levels (PGE2, PGD2, 6-ketoPGF1alpha, PGF2alpha). The skin PGD2 level and the ability of PGD2 production decreased at 48 h after repeated scratch, compared to that of normal skin, not so after single scratch. Immunohistochemical analysis and Western blotting revealed a decrease in the levels of cyclooxygenase-1 (COX-1) and hematopoietic PGD synthase in mechanically scratched skin. The reduced ability of the skin for PGD2 production following mechanical scratching could be caused by this decrease in the expression levels of COX-1 and PGD2 synthase. The results suggest that repeated scratching in mice decreases the ability of the skin to produce PGD2, which is an endogenous mediator that inhibits pruritus, resulting in the establishment of the itch-scratch circle.

The anti-pruritic efficacy of TS-022, a prostanoid DP1 receptor agonist, is dependent on the endogenous prostaglandin D2 level in the skin of NC/Nga mice.

TS-022 is a prostanoid DP(1) receptor agonist, originally developed as a novel anti-pruritic drug for atopic dermatitis. The drug has been shown to suppress scratching and improve the skin inflammation in the NC/Nga (NC) mouse, a model of atopic dermatitis. Corticosteroids are commonly used as effective agents for the treatment of atopic dermatitis. We examined the anti-pruritic efficacy of TS-022 in NC mice cohabited with skin-lesioned NC mice, which showed spontaneous scratching without skin lesions in the early phase and chronic itching with severe dermatitis in the late phase, in comparison with that of dexamethasone. We have previously reported that prostaglandin D(2) might have a physiological role in the inhibition of pruritus. While after 2 weeks of cohabitation with skin-lesioned NC mice (early phase of dermatitis, characterized by the appearance of spontaneous scratching), topically applied TS-022 exhibited a weak anti-pruritic effect in the NC mice, after 6 weeks of cohabitation (late phase, characterized by both chronic scratching and dermatitis), the drug exerted potent anti-pruritic activity. In contrast, dexamethasone exerted potent anti-pruritic effect in both the early and late phases. Indomethacin aggravated the scratching in the early phase, but had no effect in the late phase. The skin prostaglandin D(2) level was significantly increased in the early phase, to subsequently declined and return to the basal level in the late phase. The cutaneous ability for prostaglandin D(2) production following topical application of arachidonic acid or mechanical scratching was decreased in the late phase. Moreover, the expression level of the prostanoid DP(1) receptor in the skin was increased in the late phase. These findings suggest that the potent anti-pruritic activity of TS-022 in the late phase might be attributable to the decrease of endogenous prostaglandin D(2) production and increase of prostanoid DP(1) receptor expression.

Effects of TS-022, a newly developed prostanoid DP1 receptor agonist, on experimental pruritus, cutaneous barrier disruptions and atopic dermatitis in mice.

TS-022, {4-[(1R, 2S, 3R, 5R)-5-Chloro-2-((S)-3-cyclohexyl-3-hydroxyprop-1-ynyl)-3-hydroxycyclopentyl] butylthio} acetic acid monohydrate, inhibits ADP-induced platelet aggregation, an effect significantly antagonized, as in the case of prostaglandin D(2) by the prostanoid DP(1) receptor antagonist (BW A868C). TS-022 is a prostanoid DP(1) receptor agonist, originally developed as a novel anti-pruritic drug for patients with atopic dermatitis. We examined the effects of TS-022 on experimental pruritus, cutaneous barrier disruption, and atopic dermatitis and in in vitro immune function tests. Topically applied TS-022 significantly suppressed scratching in skin-lesioned NC/Nga mice from a concentration of 2.5 nM, and this scratch-suppressive activity was significantly antagonized by BW A868C. Tacrolimus (FK-506) and dexamethasone, used as reference drugs for atopic dermatitis, also exhibited suppressive effects against scratching, but only at concentrations of 125 and 25,000 microM. TS-022 applied topically, once a day for 2 days, significantly accelerated repair of the cutaneous barrier disruption caused by mechanical scratching, from concentrations of 2.5 nM. This acceleration of repair of the disrupted cutaneous barrier by this drug was also significantly antagonized by BW A868C. FK-506 and dexamethasone showed no beneficial effects on the repair of the disrupted cutaneous barrier. Repeated topical application of 2.5 microM of TS-022 and 12.5 microM of FK-506 once a day for 6 weeks significantly improved the skin inflammation scores in the NC/Nga mice. In regard to the effects of TS-022 in vitro, the inhibitory activity of TS-022 against concanavalin A-induced cytokine production by splenocytes was marginal as compared with that of FK-506 or dexamethasone. These results suggest that the beneficial therapeutic effects of TS-022 in NC/Nga mice with atopic dermatitis are mediated by its suppressive effect on scratching and its effect of accelerating repair of the disrupted cutaneous barrier, both effects being attributable to its prostanoid DP(1) receptor agonistic activity.

NT-702 (parogrelil hydrochloride, NM-702), a novel and potent phosphodiesterase inhibitor, improves reduced walking distance and lowered hindlimb plantar surface temperature in a rat experimental intermittent claudication model.

NT-702 (parogrelil hydrochloride, NM-702), 4-bromo-6-[3-(4-chlorophenyl)propoxy]-5-[(pyridin-3-ylmethyl)amino]pyridazin-3(2H)-one hydrochloride, a novel phosphodiesterase (PDE) inhibitor synthesized as a potent vasodilatory and antiplatelet agent, is being developed for the treatment of intermittent claudication (IC) in patients with peripheral arterial disease. We assessed the efficacy of NT-702 in an experimental IC model as compared with cilostazol and additionally investigated the pharmacological property in vitro and ex vivo. NT-702 selectively inhibited PDE3 (IC(50)=0.179 and 0.260 nM for PDE3A and 3B) more potently than cilostazol (IC(50)=231 and 237 nM for PDE3A and 3B) among recombinant human PDE1 to PDE6. NT-702 inhibited in vitro human platelet aggregation induced by various agonists (IC(50)=11 to 67 nM) and phenylephrine-induced rat aortic contraction (IC(50)=24 nM). Corresponding results for cilostazol were 4.1 to 17 microM and 1.0 microM, respectively. NT-702 (3 mg/kg or more) significantly inhibited ex vivo rat platelet aggregation after a single oral dose. For cilostazol, 300 mg/kg was effective. In a rat femoral artery ligation model, NT-702 at 5 and 10 mg/kg repeated oral doses twice a day (BID) for 13 days significantly improved the reduced walking distance while the lowered plantar surface temperature was improved at 2.5 mg/kg and more. Cilostazol also improved the walking distance and surface temperature at 300 mg/kg BID but significant difference was only observed for surface temperature on day 8. These results suggest that NT-702 can be expected to have therapeutic advantage for IC.

Effect of a new inhibitor of the synthesis of 20-HETE on cerebral ischemia reperfusion injury.

BACKGROUND AND PURPOSE: Arachidonic acid that is released following cerebral ischemia can be metabolized to 20-hydroxyeicosatetraenoic acid (20-HETE). 20-HETE is a potent vasoconstrictor that may contribute to ischemic injury. This study examined the effects of blockading the synthesis of 20-HETE with TS-011 on infarct size after transient occlusion of the middle cerebral artery (MCAO) of rats and after thromboembolic stroke in monkeys. METHODS: Rats were treated with TS-011 or vehicle at various times after MCAO. Infarct size was measured by 2,3,5-triphenyltetrazolium chloride (TTC) staining and plasma levels of 20-HETE were determined by liquid chromatography mass spectrometry (LC/MS). The effect of TS-011 on infarct size was also studied in monkeys after introduction of a clot into the internal carotid artery. RESULTS: Plasma levels of 20-HETE increased after MCAO in rats. TS-011 (0.01 to 1.0 mg/kg per hour) reduced infarct volume by 40%. Chronic administration of TS-011 for 7 days reduced neurological deficits after MCAO in rats. TS-011 given in combination with tissue plasminogen activator also improved neurological outcome in the stroke model in monkeys. CONCLUSIONS: These results suggest that blockade of the formation of 20-HETE with TS-011 may be useful for the treatment of ischemic stroke.

Expression of IL-31 gene transcripts in NC/Nga mice with atopic dermatitis.

To search for the pruritogen of atopic dermatitis, a characteristic symptom in atopic dermatitis patients, we examined interleukin-31 (IL-31) mRNA expression in NC/Nga mice as an animal model of atopic dermatitis. The expression of IL-31 mRNA in the skin of NC/Nga mice with scratching behavior was significantly higher than that in NC/Nga mice without scratching behavior. Our findings suggest that IL-31 may participate in the cause of itch sensation and promote scratching behavior in NC/Nga mice with atopic dermatitis.

Prostaglandin D2 and prostaglandin E2 accelerate the recovery of cutaneous barrier disruption induced by mechanical scratching in mice.

The role of prostaglandins in mechanical scratching-induced cutaneous barrier disruption in mice was investigated. Skin prostaglandins contents were measured after cutaneous barrier function was disrupted by scratching using a stainless-steal wire brush (mechanical scratching), then effects of prostanoids on recovery of cutaneous barrier functions were examined. This mechanical scratching increased transepidermal water loss and skin prostaglandins (prostaglandin D2, prostaglandin E2, 6-keto-prostaglandin F1alpha and prostaglandin F2alpha) contents, count-dependently. Topical application of indomethacin immediately after cutaneous barrier disruption delayed the recovery period of cutaneous barrier disruption. We examined effects of several prostanoids (prostaglandin D2, prostaglandin E2, prostaglandin F2alpha, prostaglandin I2 and U46619) on delay of the recovery process of mechanical scratching-induced cutaneous barrier disruption with treatment of indomethacin. Topically applied prostaglandin D2 and prostaglandin E2 accelerated the recovery of cutaneous barrier disruption and topical application of prostaglandin J2, limaprost, sulprostone and ONO-4819, but not 13,14-dihydro-15-keto-prostaglandin D2, 15-deoxy-Delta(12,14)-prostaglandin J2, 17-phenyl-trinor-prostaglandin E2 or butaprost had effects on recovery of the cutaneous barrier. These results suggest that prostaglandin D2 and prostaglandin E2 accelerate the recovery process of cutaneous barrier disruption caused by mechanical scratching, via specific prostanoid DP1, EP3 and EP4 receptors.

Antitumor effects of synthetic VEGF-receptor binding antagonist, VGA1155.

Vascular endothelial growth factor (VEGF) plays key roles in tumor angiogenesis. Therefore, VEGF and its receptors are considered to be primary targets for antiangiogenic strategy during cancer chemotherapy. Our previous study reported that VGA1155, a low-molecular-weight inhibitor of the binding of VEGF, inhibited VEGF binding to KDR/Flk-1 receptor-overexpressing cells. In the present study, the antitumor effects and antimetastatic effect of VGA1155 were examined in vivo. VGA1155 suppressed the growth of human lung, breast, colon and epidermoid cancers (LC-6, HT29, MX-1, Col-1 and A431) in the nude mouse xenograft model, and pulmonary metastasis of melanoma in the spontaneous metastasis model. These results suggest that VGA1155 has antitumor effects in vivo through the inhibition of VEGF binding to its receptors.

A novel low molecular weight antagonist of vascular endothelial growth factor receptor binding: VGA1155.

Vascular endothelial growth factor (VEGF) plays a pivotal role in the processes of angiogenesis, which is essential for the growth of solid tumors and their metastasis. Because VEGF is a critical factor in tumor survival, inhibiting VEGF would provide significant benefits in tumor therapy. To identify a compound that inhibits the binding of VEGF to its receptor, we used a high throughput screening method, finding that small molecular compounds inhibited VEGF binding. Among active compounds, 5-[N-methyl-N-(4-octadecyloxyphenyl)acetyl]amino-2-methylthiobenzoic acid (VGA1155) was selected for its potent inhibition of binding. VGA1155 inhibited [(125)I] VEGF binding to two cell lines, NIH3T3-fms-like tyrosine kinase-1 (VEGF receptor 1 transfected) cells and NIH3T3-kinase insert domain containing receptor/fetal liver kinase-1 (KDR/Flk-1; VEGF receptor 2 transfected), in a concentration-dependent manner. VGA1155 did not inhibit the binding of several other growth factors or cytokines to their receptors. Based on the results of surface plasmon resonance analysis using Biacore S51 system, it appears that this binding inhibitory property may be based on the association of VGA1155 with VEGF receptor 2 (KDR/Flk-1). Further, the interference in VEGF binding by VGA1155 in turn induces the inhibition of VEGF-induced KDR/Flk-1 autophosphorylation. VGA1155 also reduced intradermal VEGF-induced vascular permeability in guinea pigs. These findings indicate that VGA1155 inhibits not only VEGF binding to its receptors through association with KDR/Flk-1 but also VEGF function in vivo. These VGA1155 activities may provide a useful basis for the development of antiangiogenic and antitumor agents.

Persistence of Staphylococcus aureus colonization on the skin of NC/Nga mice.

BACKGROUND: Colonization of Staphylococcus aureus (S. aureus) on skin is one factor which can worsen atopic dermatitis (AD). The reduction of bacterial colonization in these lesions was reported to be effective for the treatment of subjects with AD. NC/Nga mice are recognized to be a model of AD. OBJECTIVE: We examined the susceptibility of S. aureus colonization on the skin in NC/Nga mice, as compared with findings in BALB/c mice. METHODS: The number of S. aureus on the skin was counted and serum corticosterone, serum interferon-gamma (IFN-gamma) and interleukin (IL)-12 levels were measured. The effects of dexamethasone on number of S. aureus on the skin and serum IFN-gamma and interleukin IL-12 levels were also examined. RESULTS: The number of S. aureus increased in parallel with the severity of the dermatitis in these mice, and the remaining number of S. aureus on the skin after topical treatment of S. aureus suspension was higher than that in BALB/c mice. Serum IFN-gamma and IL-12 concentrations in NC/Nga mice were lower than in BALB/c mice, and the circadian variations of serum corticosterone concentrations in NC/Nga mice tended to reveal higher levels compared with the circadian variations in BALB/c mice. Continuous administration of dexamethasone inhibited the elimination of S. aureus from skin surfaces of BALB/c mice. Serum IFN-gamma and IL-12 concentrations in dexamethasone-treated BALB/c mice were lower than those in vehicle-treated BALB/c mice. CONCLUSION: Our data support the notion that high levels of circadian variations of endogenous glucocorticoid lead to a lack of protection against bacteria and a persistence of S. aureus colonization on the skin in NC/Nga mice.

A novel low molecular weight VEGF receptor-binding antagonist, VGA1102, inhibits the function of VEGF and in vivo tumor growth.

Vascular endothelial cell growth factor (VEGF) plays an important role in the processes of angiogenesis. Angiogenesis appears to be essential for the growth of solid tumors and their metastasis. VEGF plays a principal role in tumor angiogenesis. To identify a compound that inhibits the binding of VEGF to its receptor, we used a high-throughput screening method and found that oxydibenzoic acid derivatives inhibited VEGF binding to its receptors. Among the active compounds, 5-[3-[4-(octadecyloxy)phenyl]propionylamino]-2,4'-oxydibenzoic acid (VGA1102) was selected based on its potent binding inhibitory activity. VGA1102 inhibited [(125)I]VEGF binding to both of two VEGF receptor-transfected cell lines, NIH-Flt-1 and NIH-KDR/Flk-1, in a concentration-dependent manner, with IC(50) values of 0.66+/-0.07 and 0.61+/-0.16 micro M, respectively. VGA1102 (10 micro M) exhibited inhibitory activity against VEGF-induced receptor autophosphorylation. VGA1102 also inhibited VEGF-induced growth of rat liver sinusoidal endothelial cells (IC(50)=0.89+/-0.16 micro M) as well as VEGF-induced tube formation of HUVEC in vitro. VGA1102 reduced intradermal VEGF-induced vascular permeability in guinea pigs. Treatment with VGA1102 (50 mg/kg, i.p., days 0-20) significantly increased the lifespan of MM2-bearing mice with an increase in lifespan of >195.8%, and all such mice were long-term survivors on day 71. Furthermore, VGA1102 (50 mg/kg, i.p.) administered daily suppressed the growth of nude mice transplanted with LC-6 human non-small-cell lung cancer. These results suggest that VGA1102 inhibits VEGF function resulting in inhibition of tumor angiogenesis, which led to suppression of growth of human tumors transplanted into nude mice.

Establishment and characterization of a mouse FM3A cell mutant resistant to topoisomerase II-inhibitor NC-190.

We established an NC-190-resistant cell line, FM/NC-R, from the murine mammary carcinoma cell line FM3A and examined some of its characteristics. FM/NC-R cells were prepared by mutagen treatment followed by exposure to NC-190 in the culture medium. FM/NC-R cells were 76.5 times more resistant against NC-190 than FM3A cells as measured by their growth in vitro. FM/NC-R cells also showed cross-resistance to etoposide with NC-190. Neither NC-190 nor etoposide increased the lifespan of FM/NC-R-bearing mice at doses that prolonged the lifespan of FM3A-bearing mice more than four times. This resistance was not due to the change in the concentration of NC-190 in the cells, and there was no change in the expression of P-glycoprotein, a drug efflux pump in the cells. NC-190 and etoposide are inhibitors of DNA topoisomerase II, but there was no difference in cellular content of DNA topoisomerase II between the two cell lines as determined by Western blot analysis. The stabilization of DNA-DNA topoisomerase II cleavable complexes induced by NC-190 was lost in FM/NC-R cells. It was found that Gly881, which is located in the ATP binding site, was replaced by Arg in topoisomerase IIalpha of FM/NC-R cells. These results indicate that the NC-190-resistant cell line FM/NC-R contains a mutated DNA topoisomerase IIalpha.

Prostanoid DP1 receptor agonist inhibits the pruritic activity in NC/Nga mice with atopic dermatitis.

NC/Nga mice have similar pathological and behavioral features of human atopic dermatitis and are used as a model of the disease. Under conventional circumstances, spontaneous and persistent scratching is frequent and can lead to the onset of skin inflammation. We examined the effects of several prostanoids and their related compounds on the scratching behavior of NC/Nga mice. Among them, topically applied prostaglandin D2, prostaglandin E1, prostaglandin E2 and prostaglandin I2 significantly suppressed the scratching, the order of inhibitory activities being prostaglandin D2>>prostaglandin I2>prostaglandin E1=prostaglandin E2. Prostaglandin D2 metabolite, prostaglandin J2 also significantly suppressed the scratching but not so 13,14-dihydro-15-keto-prostaglandin D2, and 15-deoxy-Delta12,14-prostaglandin J2. The order of the inhibitory activities of these prostaglandin D2 metabolites depended on affinity of the prostanoid DP1 receptor but not on the DP2 receptor (chemoattractant receptor-homologous molecule expressed on T helper2 cells, CRTH2) and PPAR-gamma receptors. Likewise, topically applied arachidonic acid significantly suppressed the scratching while indomethacin enhanced it. Pretreatment of arachidonic acid increased the skin prostaglandins (prostaglandin D2, prostaglandin E2, prostaglandin F2alpha and 6-keto-prostaglandin F1alpha) contents, but indomethacin decreased the prostaglandin D2 and prostaglandin E2 contents. On the other hand, prostaglandin D2 and indomethacin had no apparent effects on histamine-induced scratching of ICR mice. These results suggested that prostaglandin D2 plays a physiological role in inhibiting pruritus of NC/Nga mice via their specific prostanoid DP1 receptors, and that prostaglandin D2 and/or a prostanoid DP1 receptor agonist may have therapeutic effects for cases of consecutive skin inflammation.

Effect of TTC-909 in a middle cerebral artery thrombosis model in stroke-prone spontaneously hypertensive rats.

We investigated the effect of TTC-909, a preparation of the stable prostaglandin I(2) analogue clinprost (isocarbacyclin methylester; methyl 5-[(1S,5S,6R,7R)-7-hydroxy-6-[(E)-(S)-3-hydroxy-1-octenyl] bicyclo[3.3.0]oct-2-en-3-yl] pentanoate) incorporated into lipid microspheres, on infarct volume 24 h after photochemically induced thrombotic occlusion of the middle cerebral artery in stroke-prone spontaneously hypertensive rats (SHR). Under anesthesia, the photosensitizing dye rose bengal (20 mg/kg) was administered intravenously and photoirradiation with green light (wavelength 540 nm) on the middle cerebral artery above the rhinal fissure was achieved using a xenon lamp for 10 min. Infarct volume 24 h after the photochemically induced thrombotic occlusion of the middle cerebral artery was significantly larger in stroke-prone SHR than in Wistar rats. When TTC-909 in doses of 100, 300 and 900 ng/kg/h was intravenously infused for 3 h, starting immediately after the end of the 10-min photoirradiation, the infarct volume was dose-dependently reduced and was statistically significant at a dose of 900 ng/kg/h (p < 0.05). Ozagrel, a thromboxane A(2) synthetase inhibitor, significantly reduced the infarct volume. The model of photochemically induced thrombotic occlusion of the middle cerebral artery in stroke-prone SHR is very useful, because the cerebral infarction is large enough and reproducible. TTC-909 may be effective for the treatment of acute ischemic stroke.

Effects of SEA0400, a novel inhibitor of the Na+/Ca2+ exchanger, on myocardial stunning in anesthetized dogs.

Activation of the Na+/Ca2+ exchanger may contribute to Ca2+ overload during reperfusion after transient ischemia. We examined the effects of 2-[4-[(2,5-difluorophenyl) methoxy]phenoxy]-5-ethoxyaniline (SEA0400), a selective inhibitor of Na+/Ca2+ exchange, on a canine model of ischemia/reperfusion injury (myocardial stunning). Myocardial stunning was induced by a 15-min occlusion of the left anterior descending coronary artery followed by a 4-h reperfusion in anesthetized open-chest dogs. Reperfusion gradually restored myocardial percent segment shortening but remained depressed during a 4-h reperfusion period. A bolus intravenous injection of SEA0400 (0.3 or 1.0 mg/kg), given 1 min before reperfusion, improved significantly the recovery of percent segment shortening in the ischemic/reperfused myocardium. SEA0400 did not affect the hemodynamics and electrocardiogram parameters. In addition, SEA0400 did not affect reperfusion-induced change in coronary blood flow. These results suggest that the Na+/Ca2+ exchanger is involved in the stunned myocardium of dogs after reperfusion, and that SEA0400 has a protective effect against myocardial stunning in dogs.

Scratching of their skin by NC/Nga mice leads to development of dermatitis.

Effects of scratching behavior on dermatitis, transepidermal water loss (TEWL) and serum IgE concentrations were examined in NC/Nga (NC) mice with toenails (WIT) and without toenails (WOT). The first study was a preventive treatment done to cut off hind toenails before dermatitis induction and the second study was a therapeutic treatment by cutting off hind toenails of NC mice with severe dermatitis. In the preventive study, scratching behavior significantly increased in both WIT and WOT after dermatitis induction. Skin severity score, TEWL, number of mast cells and serum IgE concentration statistically increased in WIT but not in WOT after dermatitis induction. Histological changes coincided with the skin severity score in WIT, while no changes were observed in WOT. In the therapeutic study, skin severity score in WOT but not in WIT statistically decreased after cutting off the hind toenails. TEWL and numbers of mast cells in WOT were statistically lower compared with findings in WIT. Thus scratching up the skin with toenails seemed to be the most important factor leading to dermatitis in NC mice.

VGA1155, a novel binding antagonist of VEGF, inhibits angiogenesis in vitro and in vivo.

The process of angiogenesis involves the formation of new blood vessels from established vasculature and is essential for progressive tumor growth and metastasis. Since vascular endothelial growth factor (VEGF) plays a pivotal role in tumor angiogenesis, it is reasonable to expect that antagonizing VEGF binding to its receptor may be effective in cancer therapy. Our previous study found that a novel low molecular weight compound, VGA1155, inhibited binding between radioisotope-labelled VEGF and cells overexpressing its two receptors, Flt-1 and KDR/Flk-1, that is, NIH3T3-Flt-1 and NIH3T3-KDR, respectively. In the present study, we investigated the anti-angiogenic effects of VGA1155 based on VEGF inhibition. VGA1155 inhibited VEGF-induced DNA synthesis of human umbilical vein endothelial cells (HUVEC) and human retinal endothelial cells (HREC) in a concentration-dependent manner. VGA1155 also inhibited VEGF-induced tube formation of HUVEC in vitro and tumor angiogenesis toward B16-BL6 melanoma after orthotopic implantation into the skin of the back. On the other hand, VGA 1155 did not affect the proliferation of human epidermoid carcinoma (KB) cells and mouse mammary carcinoma (MM2) cells. It also had no effect on the activity of several cytosolic kinases such as p55fyn and p56lck. These findings suggest that VGA1155 inhibits endothelial cell growth and angiogenesis by inhibiting VEGF function but not non-specific cytotoxicity. VGA1155 thus exhibits promise as an antiangiogenic or anti-tumor agent with fewer side-effects.

(2S,4S)-4-Fluoro-1-{[(2-hydroxy-1,1-dimethylethyl)amino]acetyl}-pyrrolidine-2-carbonitrile monobenzenesulfonate (TS-021) is a selective and reversible dipeptidyl peptidase IV inhibitor.

The incretin hormone glucagon-like peptide-1 (GLP-1) has significant roles in the regulation of postprandial glucose metabolism, and the active form of GLP-1 is rapidly degraded by dipeptidyl peptidase (DPP)-IV. Therefore, DPP-IV inhibition is a promising approach for the treatment of type 2 diabetes. In the present study, we investigated the character of a DPP-IV inhibitor, TS-021, (2S, 4S)-4-fluoro-1-{[(2-hydroxy-1,1-dimethylethyl)amino]acetyl}-pyrrolidine-2-carbonitrile monobenzenesulfonate both in vitro and in vivo. TS-021 inhibits DPP-IV activity in human plasma with an IC(50) value of 5.34nM. In kinetics experiments, TS-021 had a relatively higher dissociation rate constant, with a k(off) value of 1.09×10(-3)s, despite exhibiting a potent human plasma DPP-IV inhibition activity with a K(i) value of 4.96nM. TS-021 exhibited significant inhibition selectivity against DPP-8 (>600 fold), DPP-9 (>1200 fold) and other peptidases examined (>15,000 fold). In normal rats, dogs and monkeys, a single oral dose of TS-021 exhibited favorable pharmacokinetic profiles. In Zucker fatty (fa/fa) rats, a rat model of obesity and impaired glucose tolerance, the oral administration of TS-021 resulted in the suppression of plasma DPP-IV activity and an increase in the active form of GLP-1. Furthermore, TS-021 exhibited a significant improvement in glucose tolerance by increasing the plasma insulin level during oral glucose tolerance tests at doses of 0.02-0.5mg/kg. These results suggest that TS-021 is a selective and reversible dipeptidyl peptidase IV inhibitor and has excellent characteristics as an oral anti-diabetic agent for postprandial hyperglycemia in patients with impaired glucose tolerance or type 2 diabetes.