Spatial Analysis of Slowly Oscillating Electric Activity in the Gut of Mice Using Low Impedance Arrayed Microelectrodes

Smooth and elaborate gut motility is based on cellular cooperation, including smooth muscle, enteric neurons and special interstitial cells acting as pacemaker cells. Therefore, spatial characterization of electric activity in tissues containing these electric excitable cells is required for a precise understanding of gut motility. Furthermore, tools to evaluate spatial electric activity in a small area would be useful for the investigation of model animals. We thus employed a microelectrode array (MEA) system to simultaneously measure a set of 8×8 field potentials in a square area of ∼1 mm². The size of each recording electrode was 50×50 µm², however the surface area was increased by fixing platinum black particles. The impedance of microelectrode was sufficiently low to apply a high-pass filter of 0.1 Hz. Mapping of spectral power, and auto-correlation and cross-correlation parameters characterized the spatial properties of spontaneous electric activity in the ileum of wild-type (WT) and W/W^v mice, the latter serving as a model of impaired network of pacemaking interstitial cells. Namely, electric activities measured varied in both size and cooperativity in W/W^v mice, despite the small area. In the ileum of WT mice, procedures suppressing the excitability of smooth muscle and neurons altered the propagation of spontaneous electric activity, but had little change in the period of oscillations. In conclusion, MEA with low impedance electrodes enables to measure slowly oscillating electric activity, and is useful to evaluate both histological and functional changes in the spatio-temporal property of gut electric activity.     

Influence of the gut microflora on protein synthesis in tissues and in the whole body of chicks.

1. The influence of the gut microflora on protein synthesis in individual tissues and in the whole body of young chicks was investigated by the large-dose injection of [3H]phenylalanine. 2. Growth of germ-free chicks was significantly better than that of conventional controls. Wet weights of liver, spleen, duodenum, jejunum + ileum and caeca were heavier in conventional birds than in germ-free counterparts. 3. Fractional rates of protein synthesis were higher in jejunum + ileum and whole body of conventional birds than in those of germ-free birds. Amounts of protein synthesized were larger in liver, jejunum + ileum and caeca in the presence of the gut microflora. 4. When tissues were classified into gut + liver and the remainder of the carcass, in the presence of the gut microflora an enhanced protein synthesis in fractional and absolute rate was found in the gut + liver, which is in direct contact or in close association with micro-organisms, whereas virtually no effect of the gut micro-organisms was detected in the remainder of the carcass. 5. The contribution of protein synthesis of gut + liver to that of the whole body was larger in conventional chicks than in germ-free birds, whereas the reverse was true for the remainder of the carcass.     

Generation of H2O2 is regulated by cytoplasmic free calcium in cultured porcine thyroid cells

Effects of calcium ionophore A23187 and BAY-K-8644, a calcium channel agonist, on cytoplasmic free calcium ([Ca2+]i) and H2O2 generation were studied in cultured porcine thyroid cells. We monitored continuously the effects of A23187 and BAY-K-8644 on [Ca2+]i and H2O2 generation, using the intracellularly trapped fluorescent Ca2+ indicator, fura-2, and homovanillic acid, respectively. A23187 and BAY-K-8644 induce an immediate increase in [Ca2+]i and H2O2 generation. The A23187- and BAY-K-8644-induced [Ca2+]i responses and H2O2 generation occur immediately, reach a maximum within several seconds, and then slowly decline. The minimum doses of A23187 or BAY-K-8644 to increase [Ca2+]i stimulate H2O2 generation. H2O2 generation is regulated by [Ca2+]i.     

A new variant of 17 alpha-hydroxylase deficiency with hyperaldosteronism in two Japanese sisters

We present a report on two sisters who have 17 alpha-hydroxylase deficiency with hyperaldosteronism. They have hypertension and hypergonadotropic hypogonadism. The steroid profiles suggest that they have 17 alpha-hydroxylase deficiency. In contrast to the classical biochemical findings in 17 alpha-hydroxylase deficiency, both of these patients have hyperaldosteronism. Thus this report describes a new variant of 17 alpha-hydroxylase deficiency with hyperaldosteronism. Dexamethasone suppressed the mineralocorticoid excess, including aldosterone, and improved their hypertension. In the untreated state, ACTH, instead of the renin-angiotensin system, regulated plasma aldosterone levels, but during dexamethasone treatment the renin-angiotensin system regulated these levels.     

Studies on the association of NIDDM in Japanese patients with hyperthyroid Graves' disease.

We attempted to analyze the association of hyperthyroid Graves' disease with non-insulin-dependent diabetes mellitus (NIDDM). Forty-nine patients (23 males and 26 females; 7.6%) of a total of 647 patients with hyperthyroid Graves' disease had NIDDM, several years before or after Graves' disease was diagnosed. Only 1 patient had insulin-dependent diabetes mellitus. Compared with the general Japanese population (n = 9,133), the incidence of NIDDM (n = 348; 3.9%) in patients with Graves' disease was higher in all age groups. Only 4 patients (8.2%) of the 49 hyperthyroid patients with NIDDM had a history of being overweight (body mass index > 25). In contrast, 276 (79.9%) of the 348 diabetic patients were currently or previously overweight. Moreover, the incidence of a family history of diabetes (13 of the 49 hyperthyroid Graves' patients with NIDDM; 26.5%) was also lower in the patients with NIDDM in the general Japanese population (50% incidence). The male:female ration in patients with Graves' disease and NIDDM was 1:1.1; much different from that in the total Graves' disease population (1:4.1). Analysis of the HLA loci A, B, C, DR and DQ (35 determinations) in 35 hyperthyroid patients with NIDDM and in 386 subjects from the general population revealed a highly significant difference between them in the incidence of HLA-Cw4, -DR2, -DQw1, -DQw3 and -DQw4. This study suggests that there was an association of Graves' disease with NIDDM. A significant association of HLA-DR and -DQ loci was observed in hyperthyroid Graves' patients with NIDDM.     

The parasitoidOoencyrtus nezarae (Hymenoptera: Encyrtidae) prefers hosts parasitized by conspecifics over unparasitized hosts

Summary Two laboratory experiments were conducted to examine the ovipositional preferences of the egg parasitoidOoencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) for parasitized and unparasitizedMegacopta punctatissimum Montandon (Hemiptera: Plataspidae). Females that had never oviposited or that had not oviposite for 3 days preferred recently parasitized hosts more than unparasitized hosts. The preference for recently parasitized hosts appeared to be mediated by the punctures in already parasitized hosts made by the ovipositor of the first female. Survival of the parasitoid progeny was lower in recently parasitized hosts than in unparasitized hosts. However, handling time of parasitized hosts was extremely short relative to that of unparasitized hosts, because the superparasitizing female could use the punctures made by the previous females. It is concluded that the females preferred the parasitized hosts over unparasitized hosts because the benefit of saving time and energy for drilling was more than the cost of progeny survival.     

Epidermal growth factor (EGF) produces inositol phosphates and increases cytoplasmic free calcium in cultured porcine thyroid cells

The initial signal for thyroid cell proliferation is unknown. This is the first report to show that epidermal growth factor (EGF) produces inositol phosphates and increases cytoplasmic free calcium ([Ca2+]i) in the thyroid gland. In cultured porcine thyroid cells, 10 nM EGF produces a breakdown of phosphatidylinositol and stimulates inositol phosphate production. Ten nM EGF increases [Ca2+]i, measured using fura-2, a fluorescent Ca2+ indicator; the EGF-induced [Ca2+]i response occurs immediately, reaches a maximum within several seconds, and then slowly declines. EGF stimulates production of inositol phosphates, which seem to increase [Ca2+]i. Inositol phosphate production and an increase in [Ca2+]i after EGF-stimulation may function as an initial signal for thyroid cell proliferation.     

Regulation of intracellular Mg2+ by superoxide in amnion cells.

Changes of intracellular free Mg2+ concentration ([Mg2+]i) in human amnion cells induced by superoxide anion were determined using a highly Mg(2+)-sensitive fluorescent dye Mg(2+)-fura2 or Mg(2+)-indol. Superoxide anion, produced by addition of xanthine oxidase to hypoxanthine, induced decrease of [Mg2+]i. The decrease was significantly inhibited by an anion channel blocker, 4,4'diisothiocyano-2,2' disulfonic acid stilbene (DIDS). Superoxide dismutase (SOD), injected into cells by cell fusion, also inhibited the change of [Mg2+]i, but catalase did not. Superoxide anion induced prompt increase of intracellular pH (pHi) as well as decrease of [Mg2+]i and subsequently activated the increase of intracellular free Ca2+ ([Ca2+]i) and the release of arachidonate. In contrast to superoxide anion, NH4Cl which induces increase of pHi in amnion cells increased [Mg2+]i. The elevation of basal level of [Mg2+]i by Mg(2+)-ionophore inhibited the change of [Ca2+]i and the release of arachidonate induced by superoxide anion. These results suggest that superoxide anion, transported through anion channels into cells, decreases [Mg2+]i directly, not due to a pH-effect and that the decrease of [Mg2+]i may regulate biological functions of the cells via increase of [Ca2+]i.