Mechanisms of PTHrP-induced inhibition of smooth muscle contractility in the guinea pig gastric antrum

BACKGROUND

Parathyroid hormone-related protein (PTHrP) that causes hypercalcemia of malignancy appears to function as an endogenous smooth muscle relaxant. For example, PTHrP released upon bladder wall distension relaxes detrusor smooth muscle to accommodate urine. Here, we explored mechanisms underlying PTHrP-induced suppression of the smooth muscle contractility in the gastric antrum that also undergoes a passive distension.

METHODS

Effects of PTHrP on phasic contractions and electrical slow waves in the antral smooth muscle of the guinea pig stomach were studied using isometric tension and intracellular microelectrode recordings, respectively. Fluorescent immunohistochemistry was also carried out to identify the distribution of PTH/PTHrP receptors.

KEY RESULTS

Parathyroid hormone-related protein (1-100 nM) reduced the amplitude of phasic contractions and the basal tension. N^ω -nitro-l-arginine (L-NA, 100 μM), a nitric oxide (NO) synthase inhibitor, or 1H-[1,2,4]oxadiazolo-[4, 3-a]quinoxalin-1-one (ODQ, 10 µM), a guanylate cyclase inhibitor, diminished the PTHrP (10 nM)-induced reduction in the amplitude of phasic contractions. SQ22536 (300 μM), an adenylate cyclase inhibitor, attenuated the PTHrP-induced reduction in basal tension. The combination of ODQ (10 μM) and SQ22536 (300 μM) inhibited the PTHrP-induced reductions in both phasic contractions and basal tension. PTHrP (100 nM) had no inhibitory effect on the electrical slow waves in the antral smooth muscle. PTH/PTHrP receptors were expressed in cell bodies of PGP9.5-positive neurons in the myenteric plexus.

CONCLUSIONS & INFERENCES

Parathyroid hormone-related protein exerts its inhibitory actions on the antral smooth muscle via both nitric oxide-cyclic guanosine monophosphate (NO-cGMP) and cyclic adenosine monophosphate (AMP) pathways. Thus, PTHrP may act as an endogenous relaxant of the gastric antrum employing the two complementary signaling pathways to ensure the adaptive relaxation of stomach.

Measurement and comparison of individual external doses of high-school students living in Japan, France, Poland and Belarus-the 'D-shuttle' project

Twelve high schools in Japan (of which six are in Fukushima Prefecture), four in France, eight in Poland and two in Belarus cooperated in the measurement and comparison of individual external doses in 2014. In total 216 high-school students and teachers participated in the study. Each participant wore an electronic personal dosimeter 'D-shuttle' for two weeks, and kept a journal of his/her whereabouts and activities. The distributions of annual external doses estimated for each region overlap with each other, demonstrating that the personal external individual doses in locations where residence is currently allowed in Fukushima Prefecture and in Belarus are well within the range of estimated annual doses due to the terrestrial background radiation level of other regions/countries.

Class IIa HDAC inhibition enhances ER stress-mediated cell death in multiple myeloma

Histone deacetylase (HDAC) inhibitors have been extensively investigated as therapeutic agents in cancer. However, the biological role of class IIa HDACs (HDAC4, 5, 7 and 9) in cancer cells, including multiple myeloma (MM), remains unclear. Recent studies show HDAC4 interacts with activating transcription factor 4 (ATF4) and inhibits activation of endoplasmic reticulum (ER) stress-associated proapoptotic transcription factor C/EBP homologous protein (CHOP). In this study, we hypothesized that HDAC4 knockdown and/or inhibition could enhance apoptosis in MM cells under ER stress condition by upregulating ATF4, followed by CHOP. HDAC4 knockdown showed modest cell growth inhibition; however, it markedly enhanced cytotoxicity induced by either tunicamycin or carfilzomib (CFZ), associated with upregulating ATF4 and CHOP. For pharmacological inhibition of HDAC4, we employed a novel and selective class IIa HDAC inhibitor TMP269, alone and in combination with CFZ. As with HDAC4 knockdown, TMP269 significantly enhanced cytotoxicity induced by CFZ in MM cell lines, upregulating ATF4 and CHOP and inducing apoptosis. Conversely, enhanced cytotoxicity was abrogated by ATF4 knockdown, confirming that ATF4 has a pivotal role mediating cytotoxicity in this setting. These results provide the rationale for novel treatment strategies combining class IIa HDAC inhibitors with ER stressors, including proteasome inhibitors, to improve patient outcome in MM.

Study of an improved Allyl Di-Glycol carbonate sheet for high energy proton detection

An allyl di-glycol carbonate (ADC) sheet which has been utilised as a neutron detector for personal dosimetry has recently been studied for its application as a device for radiation exposure control for astronauts in space, where protons are the dominant radiation. It is known that the fabrication process, modified by adding some kind of antioxidant to improve the sensitivity of ADC to high energy protons, causes a substantial increase in false tracks, which disturb the automatic counting of proton tracks using the auto-image analyser. This made clear the difficulty of fabricating ADC sheets which have sufficient sensitivity to high energy protons, while maintaining a good surface. In this study, we have tried to modify the fabrication process to improve the sensitivity to high energy protons without causing a deterioration of the surface condition of ADC sheets. We have successfully created fairly good products.

Regulation of gene expression by herbal medicines--a new paradigm of gene therapy for multifocal abnormalities of genes

Japanese herbal medicine has long been considered as only supplementary therapy to Western medicine. However, we discovered that an herbal mixture, Saiko-keishi-to-ka shakuyaku (SK, TJ-960), showed regulatory function of gene expression such as increased expression of seizure-related gene PTZ-17, proto-oncogene c-fos and heat shock protein HSP 72. These results provide a scientific basis for an important ancient concept and usage of herbal mixtures as a "therapy against diseases which will be suffered in the future". Our results also give an adequate provide break-throughs for therapy and even prevention of intractable epilepsy, Alzheimer's disease, developmental disorders during pregnancy and the postnatal period, and also probably for prevention of metastasis or relapse of various cancers.

Relationship between large conductance calcium-activated potassium channel and bursting activity

To elucidate the role of the large conductance calcium-activated potassium channel (BK(Ca) channel) in the production of bursting activity, which is characteristic of convulsions, effects of iberiotoxin (IbTX), a selective blocker of the BK(Ca) channel, on bursting activity, induced by various procedures were examined using primary cultured neurons from the cerebral cortex of mice. IbTX completely inhibited bursting activity induced by pentylenetetrazol (PTZ), caffeine, 1,4,5-inositol triphosphate (IP3) and direct forced increase of intracellular calcium. Inherent spontaneous bursting activity in the cerebral cortical neurons of the El mouse, which shows a high susceptibility to convulsions was also completely inhibited by IbTX. Apamin, a specific blocker of the small conductance calcium-activated potassium channel (SK(Ca) channel) showed no inhibition of bursting activity. These findings suggest that the BK(Ca) channel is essential for the production of bursting activity, and also suggest the possibility of clinical use of blocking agents of the BK(Ca) channel against intractable epilepsy.

Gene mapping of SEZ group genes and determination of pentylenetetrazol susceptible quantitative trait loci in the mouse chromosome

Gene mapping of the newly discovered SEZ genes (seizure-related genes) in the mouse was performed by linkage analysis. SEZ6 was on chromosome 11, SEZ12 on chromosome 16, SEZ15 on chromosome 3 and SEZ17 (PTZ17) on chromosome 18. The mouse chromosomal locus related to high susceptibility to pentylenetetrazol (PTZ) was also determined by linkage analysis using the recombinant inbred mouse, BXD (C57BLxDBA). A significant level of PTZ susceptibility was found on chromosome 2. Chromosomal loci of the newly discovered SEZ genes were not coincident with the significant chromosomal loci to PTZ susceptibility. Since epilepsy is assumed to be a disease syndrome which is probably manifested by abnormal expression of multifocal genes, determination of the role of each chromosomal locus in the provocation of seizure activity is important.

Protective effects of peony root extract and its components on neuron damage in the hippocampus induced by the cobalt focus epilepsy model

Protective effects of peony root extract and its components on neuron damage in the CA1 area of the hippocampus induced by the cobalt focus epilepsy model were examined. Neuron damage in the CA1 area of the hippocampus and frequent spike discharges induced by application of metallic cobalt to the cerebral cortex of rats were completely prevented when peony root extract was continuously administered orally at 1 g/kg/day for 30 days prior to cobalt application. Component crude gallotannin fraction showed marked but incomplete protective action. A combination of crude gallotannin fraction and paeoniflorin showed complete protective action in the same way as peony root extract against neuron damage although use of paeoniflorin alone had no effect. These findings together with our previous reports indicate that peony root extract and its component, gallotannin, have excellent protective effects on neuron damage in addition to anticonvulsant action by prior oral administration.

[Marked increase of atmospheric pollen dispersion of ragweed (Ambrosia spp.)--annual changes in atmospheric pollen counts of major allergen plants in autumn in Saitama Prefecture]

An annual atmospheric pollen survey was performed for 14 consecutive years in the autumn at Sakado city, Saitama prefecture. The survey was performed on the transition of pollen dispersion of major allergen plants: ragweed (Ambrosia spp.), Humulus japonicus, Artemisia spp. and Gramineae. 1. Annual total pollen count of ragweed showed marked increases beginning from 1991. Total pollen count in 1991 was 8.8 times and that in 1996 was 18.6 times that in 1983. This increase is probably caused by marked proliferation of giant ragweed which is left without mowing as it is on a dry riverbed, and consequently produces much more pollen than short ragweed. 2. Annual increases in total pollen counts of other major plants which disperse their pollen in the same season as ragweed were 0.95 times in 1991 and 0.5 times in 1996 that in 1983 for Humulus japonicus, 0.68 times in 1991 and 1.5 times in 1996 that in 1983 for Artemisia spp. and 1.3 times in 1991 and 1.4 times in 1996 that in 1983 for Gramineae. None of these species showed a marked increase of pollen dispersion although they showed some annual variation. The above findings suggest that changes in the proliferous state of various allergenic plants due to environmental change should be considered with respect to characteristics of pollen allergy.

[Pollen dispersion of Cryptomeria japonica in autumn]

To clarify the significance of pollen dispersion of Cryptomeria japonica in autumn, the distribution pattern of pollen dispersion using specimens collected from 1987 to 1995 by Durhum collector was examined. After the dispersion period in the spring, the pollen count was suddenly decreased. The total pollen count from October to December showed no relation to the total pollen count for that of in spring of the same year; but it was closely correlated (r = 0.877) with the total pollen count during the dispersion period in the spring of the next year. In particular, accurate correlation between the total pollen count during November and that in January to May of the following year was observed with the correlation index of r = 0.909. Patients with a pollinosis probably for Cryptomeria japonica were also observed in the autumn. These results suggest that we can forecast the degree of pollen dispersion of Cryptomeria japonica in the coming year from the total pollen count during November of the year before.

Septate-like junctions in the normal male rat pituitary gland

Septate-like junctions were observed in the rat anterior pituitary gland of the adult male solely between adjacent folliculo-stellate cells. Considering their location, it is presumed that their function is cellular adhesion and mechanical support for the hypophyseal follicles.