Functional analysis of thermo-sensitive TRPV1 in an aquatic vertebrate, masu salmon (Oncorhynchus masou ishikawae).

Transient receptor potential vanilloid 1 (TRPV1) is mainly expressed in nociceptive primary sensory neurons and acts as a sensor for heat and capsaicin. The functional properties of TRPV1 have been reported to vary among species and, in some cases, the species difference in its thermal sensitivity is likely to be associated with thermal habitat conditions. To clarify the functional properties and physiological roles of TRPV1 in aquatic vertebrates, we examined the temperature and chemical sensitivities of TRPV1 in masu salmon (Oncorhynchus masou ishikawae, Om) belonging to a family of salmonids that generally prefer cool environments. First, behavioral experiments were conducted using a video tracking system. Application of capsaicin, a TRPV1 agonist, induced locomotor activities in juvenile Om. Increasing the ambient temperature also elicited locomotor activity potentiated by capsaicin. RT-PCR revealed TRPV1 expression in gills as well as spinal cord. Next, electrophysiological analyses of OmTRPV1 were performed using a two-electrode voltage-clamp technique with a Xenopus oocyte expression system. Heat stimulation evoked an inward current in heterologously expressed OmTRPV1. In addition, capsaicin produced current responses in OmTRPV1-expressing oocytes, but higher concentrations were needed for its activation compared to the mammalian orthologues. These results indicate that Om senses environmental stimuli (heat and capsaicin) through the activation of TRPV1, and this channel may play important roles in avoiding environments disadvantageous for survival in aquatic vertebrates.

Reduction of extracellular sodium evokes nociceptive behaviors in the chicken via activation of TRPV1.

Transient receptor potential vanilloid 1 (TRPV1), a non-selective cation channel, is mainly expressed in nociceptive primary sensory neurons. Sensitivity of TRPV1 to several stimuli is known to vary among species, specifically, the avian orthologue is nearly insensitive to capsaicin. Extracellular sodium ions ([Na+]o) regulate TRPV1 activity in mammals, but their regulatory role on chicken TRPV1 (cTRPV1) is unknown. Here, we focused on the actions of capsaicin and low [Na+]o on cTRPV1 activity. In chicken dorsal root ganglion (cDRG) neurons, capsaicin elicited [Ca2+]i increases, but its effective concentration was much higher than those in mammals. Low [Na+]o evoked [Ca2+]i increases in cDRG neurons in a decreasing [Na+]o-dependent manner and the complete removal of [Na+]o (0Na) produced maximal effects. The population of 0Na-sensitive neurons was mostly overlapped with those of proton- and capsaicin-sensitive ones. Low [Na+]o synergistically potentiated the capsaicin- and proton-induced TRPV1 activation in cDRG neurons. In HEK293 cells expressing cTRPV1 (cTRPV1-HEK), capsaicin elicited [Ca2+]i increases with an EC50 of 11.8 µM, and low [Na+]o also did. Well-defined mammalian TRPV1 antagonists hardly suppressed cTRPV1 activation by low [Na+]o. 0Na evoked outwardly rectified currents in cTRPV1-HEK. Mutagenesis analyses revealed a possible interaction of [Na+]o with the proton-binding sites of cTRPV1. The administration of capsaicin and 0Na to chick eyes elicited pain-related behaviors. These results suggest that low [Na+]o is capable of activating cTRPV1 in vitro, resulting in pain in vivo. Our data demonstrate that characterization of the cTRPV1 function is important to understand activation mechanisms of TRPV1.

Oral administration of milk-derived phospholipids inhibits penetration of cutaneous nerve fibres into epidermis in a mouse model of acute dry skin.

The density of intraepidermal nerve fibres has been shown to be higher in itchy dry skin than in healthy skin, suggesting that epidermal hyperinnervation is at least partly involved in peripheral itch sensitization. We investigated whether oral administration of milk-derived phospholipids (MPLs) would inhibit epidermal hyperinnervation in a mouse model of dry skin. We found that the number of intraepidermal nerve fibres was significantly lower in the MPL group than in the control group. Expression of nerve growth factor (NGF) levels in the epidermis was significantly decreased by oral administration of MPLs, whereas expression of semaphorin (Sema)3A, a nerve repulsion factor, was increased in the MPL group. These results suggest that dietary MPLs attenuate the penetration of nerve fibres into the epidermis by reducing epidermal NGF levels and increasing Sema3A level. Thus, dietary MPLs may have beneficial effects in the prevention and/or alleviation of dry skin-induced itch by reducing intraepidermal nerve fibre density.

Lafutidine, a histamine H2 receptor antagonist with mucosal protective properties, attenuates 5-fluorouracil-induced intestinal mucositis in mice through activation of extrinsic primary afferent neurons.

Intestinal mucositis accompanied by severe diarrhea is one of the most common side effects during cancer chemotherapy. Lafutidine, a histamine H2 receptor antagonist with mucosal protective properties via sensory afferent neurons, is used for the treatment of upper gastrointestinal diseases. The present study investigated the effects of lafutidine on 5-fluorouracil (5-FU)-induced intestinal mucositis induced in mice. Male C57BL/6 wild-type (WT), sensory deafferented mice, and transient receptor potential vanilloid subfamily 1 knockout (TRPV1KO) mice were used. Animals were administered 5-FU once daily, while lafutidine and famotidine were administered twice daily for 6 days. Repeated administration of 5-FU caused severe intestinal mucositis, characterized by shortening of villi and destruction of crypts and was accompanied by diarrhea and body weight loss. Daily administration of lafutidine reduced the severity of intestinal mucositis, diarrhea and body weight loss in a dose-dependent manner, while famotidine had no effect on intestinal mucositis. The preventive effects of lafutidine were completely abolished in sensory deafferented and TRPV1-KO mice. Lafutidine significantly suppressed 5-FU-increased MPO activity and inflammatory cytokine expression on day 6, but not apoptosis induction in intestinal crypts on day 1. Lafutidine induced Alcian Blue and PAS-positive mucus production in the small intestine. These findings suggest that lafutidine attenuates 5-FU-induced intestinal mucositis, most likely by increasing mucus production via activation of sensory afferent neurons. Furthermore, intact TRPV1 signaling is essential for the activation of sensory afferent neurons induced by lafutidine. Therefore, lafutidine is more useful than other common antacids for the treatment of intestinal mucositis during cancer chemotherapy.

Two different avian cold-sensitive sensory neurons: Transient receptor potential melastatin 8 (TRPM8)-dependent and -independent activation mechanisms.

Sensing the ambient temperature is an important function for survival in animals. Some TRP channels play important roles as detectors of temperature and irritating chemicals. There are functional differences of TRP channels among species. TRPM8 in mammals is activated by cooling compounds and cold temperature, but less information is available on the functional role of TRPM8 in avian species. Here we investigated the pharmacological properties and thermal sensitivities of chicken TRPM8 (cTRPM8) and cold-sensitive mechanisms in avian sensory neurons. In heterologously expressed cTRPM8, menthol and its derivative, WS-12 elicited [Ca2+]i increases, but icilin did not. In chicken sensory neurons, icilin increased [Ca2+]i, in a TRPA1-dependent manner. Icilin selectively stimulated heterologously expressed chicken TRPA1 (cTRPA1). Similar to mammalian orthologue, cTRPM8 was activated by cold. Both heterologous and endogenous expressed cTRPM8 were sensitive to mammalian TRPM8 antagonists. There are two types of cold-sensitive cells regarding menthol sensitivity in chicken sensory neurons. The temperature threshold of menthol-insensitive neurons was significantly lower than that of menthol-sensitive ones. The population of menthol-insensitive neurons was large in chicken but almost little in mammals. The cold-induced [Ca2+]i increases were not abolished by the external Ca2+ removal or by blockades of PLC-IP3 pathways and ryanodine channels. The cold stimulation failed to evoke [Ca2+]i increases after intracellular Ca2+ store-depletion. These results indicate that cTRPM8 acts as a cold-sensor similar to mammals. It is noteworthy that TRPM8-independent cold-sensitive neurons are abundant in chicken sensory neurons. Our results suggest that most of the cold-induced [Ca2+]i increases are mediated via Ca2+ release from intracellular stores and that these mechanisms may be specific to avian species.

PCDD, PCDF, dl-PCB and organochlorine pesticides monitoring in São Paulo City using passive air sampler as part of the Global Monitoring Plan.

The persistent organic pollutants (POPs), such as organochlorine pesticides and PCBs, are ordinarily monitored in the aquatic environment or in soil in the environmental quality monitoring programs in São Paulo, Brazil. One of the core matrices proposed in the POPs Global Monitoring Plan (GMP) from the Stockholm Convention list is the ambient air, which is not a usual matrix for POPs monitoring in the country. In this study POP levels were evaluated in the air samples from an urban site in São Paulo City over five years, starting in 2010 as a capacity building project for Latin America and the Caribbean region for POP monitoring in ambient air using passive samplers. Furthermore, after the end of the Project in 2012, the monitoring continued in the same sampling site as means to improving the analytical capacity building and contribute to the GMP data. The POPs monitored were 17 congeners of 2,3,7,8 chloro-substituted PCDDs and PCDFs, dioxin-like PCBs, indicator PCBs, organochlorine pesticides and toxaphene. The results show a slight decrease in PCDD/F, dl-PCBs and indicator PCBs levels along the five years. The organochlorine pesticide endosulfan was present at its highest concentration at the beginning of the monitoring period, but it was below detection level in the last year of the monitoring. Some other organochlorine pesticides were detected close to or below quantitation limits. The compounds identified were dieldrin, chlordane, α-HCH, γ-HCH, heptachlor, heptachlor epoxide, hexachlorobenzene and DDTs. Toxaphene congeners were not detected. These results have confirmed the efficacy of passive sampling for POP monitoring and the capacity building for POP analysis and monitoring was established. However more needs to be done, including expansion of sampling sites, new POPs and studies on sampling rates to be considered in calculating the concentration of POPs in ambient air using a passive sampler.

Involvement of transient receptor potential A1 channel in algesic and analgesic actions of the organic compound limonene.

BACKGROUND: TRPA1 is a Ca-permeable nonselective cation channel expressed in sensory neurons and acts as a nocisensor. Recent reports show that some monoterpenes, a group of naturally occurring organic compounds, modulate TRP channel activity. Here, we report that limonene, being contained in citrus fruits and mushrooms, shows a unique bimodal action on TRPA1 channel. METHODS: We examine the effects of limonene on sensory neurons from wild-type, TRPV1- and TRPA1-gene-deficient mice and on heterologously expressed channels in vitro. Molecular determinants were identified with using mutated channels. Cellular excitability is monitored with ratiometric Ca imaging. Nociceptive and analgesic actions of limonene are also examined in vivo. RESULTS: In wild-type mouse sensory neurons, limonene increased the intracellular Ca(2+) concentration ([Ca(2+) ]i ), which was inhibited by selective inhibitors of TRPA1 but not TRPV1. Limonene-responsive neurons highly corresponded to TRPA1 agonist-sensitive ones. Limonene failed to stimulate sensory neurons from the TRPA1 (-/-) mouse. Heterologously expressed mouse TRPA1 was activated by limonene. Intraplantar injection of limonene elicited acute pain, which was significantly less in TRPA1 (-/-) mice. Systemic administration of limonene reduced nociceptive behaviours evoked by H2 O2 . In both heterologously and endogenously expressed TRPA1, a low concentration of limonene significantly inhibited H2 O2 -induced TRPA1 activation. TRPA1 activation by limonene was abolished in H2 O2 -insensitive cysteine-mutated channels. CONCLUSIONS: Topically applied limonene stimulates TRPA1, resulting in elicitation of acute pain, but its systemic application inhibits nociception induced by oxidative stress. Because limonene is a safe compound, it may be utilized for pain control due to its inhibition of TRPA1 channels. What does this study add: Limonene, a monoterpene in essential oils of various plants, has been known for its antitumor and anti-inflammatory properties. However, molecular basis of their actions has not been identified. This study shows that limonene activates nociceptive TRPA1 and elicits acute pain, when it is topically applied. In addition, systemic application of limonene exerts inhibitory effects on nociception induced by an oxidative stress-induced TRPA1 activation.

Long-term complications after liver transplantation.

BACKGROUND: Along with an increased number of cases of liver transplantation (LT), perioperative mortality has decreased and short-term survival has improved. However, long-term complications have not been fully elucidated today. PURPOSE: Chronic complications were analyzed individually to find risk factors and to improve long-term outcomes after LT. SUBJECTS: There were 63 cases of LT from our outpatient clinic that were included in this study. Among them, 58 were performed using living donor LT and 5 were performed using deceased donor LT. Original diseases mainly consisted of hepatitis C virus (HCV; 45.9%) and hepatitis B virus (23.0%). FINDINGS: The median follow-up was 5.4 ± 3.3 years (range, 0.1∼17 years). Overall survival at 2, 3, 5, and 10 years was 89.3%, 83.4%, 81.3%, and 81.3%, respectively. Long-term complications mainly consisted of renal dysfunction (62.7%), dyslipidemia (29.4%), diabetes mellitus (21.6%), and arterial hypertension (21.6%). In univariate analysis, HCV (P = .03) and elapsed years after LT (P = .02) were identified as predictive factors for arterial hypertension and recipient age >50 (P = .03), and elapsed years after LT for renal dysfunction (P = .03), respectively. In multivariate Cox regression analysis, HCV (odds ratio [OR] 5.25, 95% confidence interval [CI] 1.05-34.06, P = .04) was identified as a predictive factor for arterial hypertension, and recipient age older than 50 years for renal dysfunction (OR 5.67, 95% CI 1.34-28.88, P = .02). The number of elapsed years after transplantation was also identified as a predictive factor for arterial hypertension/dyslipidemia/renal dysfunction (OR 13.88/14.15/4.10, 95% CI 1.91-298.26/2.18-290.78/1.09-18.03, P = .01/.003/.04). Fifty percent of the recipients developed renal dysfunction within 8 years after LT, and fluctuation of estimated glomerular filtration rate (eGFR) within 3 months after LT was successfully associated with an annual decrease of eGFR (r(2) value = 0.574, P < .0001). CONCLUSION: Renal dysfunction is the most frequent chronic complication after LT. As chronic individual eGFR can be now accurately predicted with deterioration speed, recipient strata for renal protection strategies should be precisely targeted.

Neurotropin inhibits the increase in intraepidermal nerve density in the acetone-treated dry-skin mouse model.

Epidermal hyperinnervation is considered one cause of sensitization to itch, and is thought to regulated by keratinocyte-derived axonal guidance molecules, including nerve growth factor (NGF) and semaphorin (Sema)3A. Neurotropin (NTP) shows antipruritic effects in allergic disease and is also used for pain relief. Using cultured rat dorsal root ganglion neurones, we previously found that NTP inhibited NGF-induced neurite outgrowth. However, no such inhibitory effect has been shown in vivo. We therefore assessed the effects of intraperitoneal administration of NTP on nerve density and expression of NGF and Sema3A mRNAs in the epidermis of acetone-treated mice showing epidermal hyperinnervation. We found that NTP significantly reduced intraepidermal nerve growth in these acetone-treated mice. NTP significantly upregulated epidermal Sema3A mRNA, but had no effect on expression of epidermal NGF mRNA. These findings indicate that NTP may reduce intraepidermal nerve density by inducing expression of Sema3A in the epidermis.

Impact of antihypertensive medication adherence on blood pressure control in hypertension: the COMFORT study.

BACKGROUND: It has not been fully elucidated whether antihypertensive medication adherence affects blood pressure (BP) control in hypertension cases. AIM: To investigate the association of adherence to antihypertensive drug regimens and BP control using data from the Combination Pill of Losartan Potassium and Hydrochlorothiazide for Improvement of Medication Compliance Trial (COMFORT) study. DESIGN: An observational analysis from a randomized controlled trial. METHODS: A total of 203 hypertensive subjects were randomly assigned to a daily regimen of a combination pill (losartan 50 mg/hydrochlorothiazide 12.5 mg) or two pills, an angiotensin II receptor blocker and a thiazide diuretic. Medication adherence calculated based on pill counts and BPs was evaluated at 1, 3 and 6 months after randomization. RESULTS: The subjects were divided into three groups according to their adherence, i.e. relatively low-adherence (<90%; n = 19), moderate-adherence (90-99%; n = 71) and high-adherence (100%; n = 113) groups. Clinical characteristics of the subjects including BP, sex, randomized treatments and past medical history did not differ significantly among the three groups. Achieved follow-up BPs over the 6-month treatment period, which were adjusted for age, sex, baseline BP and randomized treatment, were significantly higher in the low-adherence group (135/78 mmHg) compared with the high-adherence (130/74 mmHg; P = 0.02/0.02) and the moderate-adherence (128/74 mmHg; P = 0.003/0.02) groups. CONCLUSION: Low adherence to an antihypertensive-drug regimen was associated with poor BP control.

Cross-sensitization of histamine-independent itch in mouse primary sensory neurons.

Overexpression of pruritogens and their precursors may contribute to the sensitization of histamine-dependent and -independent itch-signaling pathways in chronic itch. We presently investigated self- and cross-sensitization of scratching behavior elicited by various pruritogens, and their effects on primary sensory neurons. The MrgprC11 agonist BAM8-22 exhibited self- and reciprocal cross-sensitization of scratching evoked by the protease-activated receptor-2 (PAR-2) agonist SLIGRL. The MrgprA3 agonist chloroquine unidirectionally cross-sensitized BAM8-22-evoked scratching. Histamine unidirectionally cross-sensitized scratching evoked by chloroquine and BAM8-22. SLIGRL unidirectionally cross-sensitized scratching evoked by chloroquine. Dorsal root ganglion (DRG) cells responded to various combinations of pruritogens and algogens. Neither chloroquine, BAM8-22 nor histamine had any effect on responses of DRG cell responses to subsequently applied pruritogens, implying that their behavioral self- and cross-sensitization effects are mediated indirectly. SLIGRL unilaterally cross-sensitized responses of DRG cells to chloroquine and BAM8-22, consistent with the behavioral data. These results indicate that unidirectional cross-sensitization of histamine-independent itch-signaling pathways might occur at a peripheral site through PAR-2. PAR-2 expressed in pruriceptive nerve endings is a potential target to reduce sensitization associated with chronic itch.

H(2)S functions as a nociceptive messenger through transient receptor potential ankyrin 1 (TRPA1) activation.

Hydrogen sulfide (H(2)S), an endogenous gasotransmitter, modulates various biological functions, including nociception. It is known that H(2)S causes neurogenic inflammation and elicits hyperalgesia. Here we show that H(2)S activates mouse transient receptor potential ankyrin 1 (TRPA1) channels and elicits acute pain, using TRPA1-gene deficient mice (TRPA1(-/-)) and heterologous expression system. In wild-type mouse sensory neurons, H(2)S increased the intracellular Ca(2+) concentration ([Ca(2+)](i)), which was inhibited by ruthenium red (a nonselective TRP channel blocker) and HC-030031 (a TRPA1 blocker). H(2)S-responsive neurons highly corresponded to TRPA1 agonist-sensitive ones. [Ca(2+)](i) responses to H(2)S were observed in neurons from transient receptor potential vanilloid 1 (TRPV1(-/-)) mice but not from TRPA1(-/-) mice. Heterologously expressed mouse TRPA1, but not mouse TRPV1, was activated by H(2)S. H(2)S-induced [Ca(2+)](i) responses were inhibited by dithiothreitol, a reducing agent. Analyses of the TRPA1 mutant channel revealed that two cysteine residues located in the N-terminal internal domain were responsible for the activation by H(2)S. Intraplantar injection of H(2)S into the mouse hind paw caused acute pain which was significantly less in TRPA1(-/-) mice. The [Ca(2+)](i) responses to H(2)S in sensory neurons and in heterologously expressed channels, and pain-related behavior induced by H(2)S were enhanced under acidic conditions. These results suggest that H(2)S functions as a nociceptive messenger through the activation of TRPA1 channels. TRPA1 may be a therapeutic target for H(2)S-related algesic action, especially under inflammatory conditions.

Significance of hair-dye base-induced sensory irritation.

Oxidation hair-dyes, which are the principal hair-dyes, sometimes induce painful sensory irritation of the scalp caused by the combination of highly reactive substances, such as hydrogen peroxide and alkali agents. Although many cases of severe facial and scalp dermatitis have been reported following the use of hair-dyes, sensory irritation caused by contact of the hair-dye with the skin has not been reported clearly. In this study, we used a self-assessment questionnaire to measure the sensory irritation in various regions of the body caused by two model hair-dye bases that contained different amounts of alkali agents without dyes. Moreover, the occipital region was found as an alternative region of the scalp to test for sensory irritation of the hair-dye bases. We used this region to evaluate the relationship of sensitivity with skin properties, such as trans-epidermal water loss (TEWL), stratum corneum water content, sebum amount, surface temperature, current perception threshold (CPT), catalase activities in tape-stripped skin and sensory irritation score with the model hair-dye bases. The hair-dye sensitive group showed higher TEWL, a lower sebum amount, a lower surface temperature and higher catalase activity than the insensitive group, and was similar to that of damaged skin. These results suggest that sensory irritation caused by hair-dye could occur easily on the damaged dry scalp, as that caused by skin cosmetics reported previously.

Neurotropin inhibits both capsaicin-induced substance P release and nerve growth factor-induced neurite outgrowth in cultured rat dorsal root ganglion neurones.

BACKGROUND: Neurotropin (NTP), a biological extract from rabbit skin inoculated with vaccinia virus, is an effective analgesic and anti-allergic agent, and has antipruritic effects in various dermatoses including eczema, dermatitis and urticaria. In patients receiving haemodialysis who have pruritus, NTP appears to exert its antipruritic effect by lowering the plasma levels of substance P (SP), but its underlying mechanisms are not fully understood. AIM: To investigate the antipruritic mechanisms of NTP. METHODS: The effects of NTP on capsaicin-induced SP release from neonatal rat dorsal root ganglion (DRG) neurones were assessed by measuring SP concentrations in culture media by a competitive ELISA. The effects of NTP on nerve growth factor (NGF)-induced neurite outgrowth were assessed by measuring the length of the longest process of cultured DRG neurones. The neuronal cytotoxicity of NTP was determined using a methylthiazole tetrazolium cytotoxicity assay. RESULTS: NTP dose-dependently inhibited capsaicin-induced release of SP from cultured DRG neurones, whereas NTP alone had no effect on SP release. Moreover, NTP dose-dependently inhibited NGF-induced neurite outgrowth in cultured DRG neurones. NTP had no observable cytotoxicity. CONCLUSIONS: These results suggest that NTP exerts its antipruritic effects by inhibiting both SP release and neurite outgrowth of cutaneous sensory nerves.

In vitro model for penetration of sensory nerve fibres on a Matrigel basement membrane: implications for possible application to intractable pruritus.

BACKGROUND: Epidermal hyperinnervation occurs in dermatoses with intractable pruritus, such as atopic dermatitis, suggesting that the hyperinnervation is partly responsible for abnormal itch perception. OBJECTIVES: To investigate the mechanisms of penetration of sensory nerve fibres into the basement membrane of the skin. METHODS: A rat dorsal root ganglion neurone culture system consisting of Matrigel and a Boyden chamber containing a nerve growth factor (NGF) concentration gradient was used. In some experiments, matrix metalloproteinase (MMP) blockers and semaphorin 3A (Sema3A) were added to the culture system. Matrigel-coated membranes were stained with anti-Tau antibody, and the number of nerve fibres that crossed the membrane was counted. Expression of MMPs in the cultured neurones was examined at mRNA and protein levels by quantitative reverse transcription-polymerase chain reaction and immunocytochemistry, respectively. The activity was also examined by zymography. RESULTS: Nerve fibres penetrated into Matrigel in the presence of an NGF concentration gradient, which was dose-dependently inhibited by GM6001, a broad-spectrum MMP inhibitor. Transcripts for MMP2, but not MMP9, were increased in the cultured neurones, and the penetration was dose-dependently inhibited by MMP-2 blockers. MMP-2 and its activity were partially localized on the NGF-responsive growth cones. NGF also upregulated pro-MMP-2 activation molecules in the cultured neurones. Sema3A stimulation showed the opposite effects on these NGF-dependent events. Interestingly, MMP2 expression was modulated by extracellular matrix (ECM) substrates for this enzyme. CONCLUSIONS: Membrane-associated MMP-2 contributes to penetration of nerve fibres into Matrigel through modulation by axonal guidance molecules and/or ECM. These findings provide insight for understanding the development of intractable pruritus involving epidermal nerve density.

Effect of miglitol, an alpha-glucosidase inhibitor, on atherogenic outcomes in balloon-injured diabetic rats.

This study investigates the effects of miglitol, an alpha-glucosidase inhibitor, on the development of balloon-injured neointimal thickening in left common carotid artery, and the changes of glucose metabolism and inflammatory responses in Wistar fatty rats, an obese-hyperglycemic animal model, and their littermates, Wistar lean rats. Miglitol was orally administered at 40 mg/100 g of high-fat diet containing 45% kcal as fat to 12-week-old rats for 29 days, and age-matched rats without the agent were used as the respective controls. Balloon catheterization in the left common carotid artery was performed on day 15, and the artery was removed on day 29. Compared with the area ratio of the neointima/media in fatty rats without treatment, those in fatty rats with miglitol and lean rats without treatment were significantly decreased to 80%. The administration of miglitol significantly decreased the levels of plasma glucose, glycoalbumin and high-sensitivity C-reactive protein, and elevated the high-density lipoprotein-cholesterol level in fatty rats. These findings suggest that miglitol could be effective for the suppression of atherogenic outcomes in diabetic Wistar fatty rat, suggesting that the agent may have clinical benefits and contribute to prevent diabetic macroangiopathy.

Effect of tyrosine kinase inhibition by imatinib mesylate on mast cell tumors in dogs.

BACKGROUND: Imatinib mesylate is a small molecule targeted at dysregulated protein-tyrosine kinase. Mutation of c-kit exon 11, which induces constitutive phosphorylation of KIT, is one of the mechanisms for the development or progression of mast cell tumor (MCT) in dogs. The purpose of this study was to examine the therapeutic potential of imatinib mesylate in canine MCT. HYPOTHESIS: Imatinib mesylate has activity against MCT in dogs, and response to treatment can be correlated to presence of mutation within exon 11 of c-kit. ANIMALS: Twenty-one dogs with MCT with gross tumor burden and median tumor size of 7.2 cm (range, 1.0-25.3 cm) before treatment. METHODS: Tumors were analyzed for mutation of c-kit exon 11. Imatinib mesylate was administered PO to the dogs at a dose of 10 mg/kg daily for 1-9 weeks. RESULTS: Ten of 21 dogs (48%) had some beneficial response to imatinib mesylate treatment within 14 days of treatment initiation. All 5 dogs with a demonstrable c-kit mutation in exon 11 responded to the drug (1 complete remission, 4 partial remission). CONCLUSIONS AND CLINICAL IMPORTANCE: Imatinib mesylate has clinical activity against MCT in dogs. Response could not be predicted based on presence of absence of a mutation in exon 11 of c-kit.

Inhibition of the transient receptor potential cation channel TRPM2 by 2-aminoethoxydiphenyl borate (2-APB).

BACKGROUND AND PURPOSE: Transient receptor potential melastatin 2 (TRPM2) is a non-selective Ca(2+)-permeable cation channel and is known to be activated by adenosine 5'-diphosphoribose (ADP-ribose) and hydrogen peroxide. TRPM2 current responses are reported to be drastically potentiated by the combination of each of these ligands with heat. Furthermore, the combination of cyclic ADP-ribose with heat also activates TRPM2. Although flufenamic acid, antifungal agents (miconazole and clotrimazole), and a phospholipase A(2) inhibitor (N-(p-amylcinnamoyl)anthranilic acid) inhibit TRPM2, their inhibition was either gradual or irreversible. EXPERIMENTAL APPROACH: To facilitate future research on TRPM2, we screened several compounds to investigate their potential to activate or inhibit the TRPM2 channels using the patch-clamp technique in HEK293 cells, transfected with human TRPM2. KEY RESULTS: 2-aminoethoxydiphenyl borate (2-APB) exhibited a rapid and reversible inhibition of TRPM2 channels that had been activated by its ADP-ribose or cADP-ribose and heat in a dose-dependent manner (IC(50) about 1 microM). 2-APB also inhibited heat-evoked insulin release from pancreatic islets, isolated from rats. CONCLUSIONS AND IMPLICATIONS: 2-APB proved to be a powerful and effective tool for studying the function of TRPM2.