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Biomedical subjects

K Ando

Publications and source records attributed to K Ando.

At least 325 records · Page 18Linked to original sources
PubMed1994

Portal vein aneurysm in the liver associated with multiple vascular malformations.

Portal vein aneurysm (PVA) includes focal dilatation of the portal vein, and was formerly thought to be a rare disease. We report a 46-year-old man with chronic aggressive hepatitis and intrahepatic portal vein aneurysm communicating with the hepatic vein. Hemangiomas in the liver and intracranial arteriovenous malformation (AVM) were also found. To our knowledge, this is the first report of a case of PVA in a patient with congenital intracranial AVM. As the PVA in this patient communicated with the hepatic vein, and as hemangiomas in the liver and intracranial AVM were also present, the pathogenesis in this patient seems to have been congenital anomaly of the vasculature.

Aneurysm↗
PubMed1994

Systematic synthesis of N-methyl-1-deoxynojirimycin-containing, Le(x), Le(a), sialyl-Le(x) and sialyl-Le(a) epitopes recognized by selectins.

A systematic synthesis of the N-methyl-1-deoxynojirimycin-containing oligosaccharides related to the Lewis x, Lewis a, sialyl-Lewis x and sialyl-Lewis a antigens has been achieved. The couplings of the suitably protected 1-deoxynojirimycin derivative 10 with methyl-1-thioglycosides (glycosyl donors) of L-fucose (11), D-galactose (15) and alpha-sialyl-(2-->3)-D-galactose (27) were carried out by using dimethyl(methylthio)sulfonium triflate (DMTST) or N-iodosuccinimide/trifluoromethanesulfonic acid (NIS/TfOH) as the glycosyl promoter. The resulting di- and tri-saccharides were each converted, by further cross glycosylations with 11, 15 or 27, to the desired tri- and tetra-saccharides 3-6 that inhibit the recognition between sialyl-Lewis x and selectins, a family of leukocyte cell adhesion molecules.

1-Deoxynojirimycin↗
PubMed1994

Migration and development of the larvae of Gnathostoma nipponicum in the rat, second intermediate or paratenic host, and the weasel, definitive host.

Migration and development of the larvae of Gnathostoma nipponicum in the rat as second intermediate or paratenic host and the weasel as definitive host were examined to clarify the pathogenesis in each animal. The advanced third-stage larvae (AdL3) given orally to rats remained in the stomach for 12 h post-infection (PI). After that, larvae transiently invaded various organs and finally moved into the muscle within 48 h. The percentage of eosinophils in the blood taken from the jugular vein of rats infected with AdL3 reached a maximum (about 6%) on day 20 PI and then decreased. IgG antibody titre for G. nipponicum measured by ELISA began to increase on day 5 PI and reached a plateau on day 20 PI. The AdL3 given orally to weasels moved from the stomach into the muscle and then increased in size. Half of them invaded the muscle within 5 days, whereas the majority of them invaded the muscles within 20 days PI. Morphology of worms which invaded the muscles indicated that they were still the larval form with three rows of hooklets on the head bulb. The larvae in the muscles developed to young adult worms with seven rows of hooklets on the head bulb within 40 days PI. These young adult worms invaded the oesophageal wall and formed a tumour within 60 days PI. It was presumed that worms invaded the oesophageal wall through the adventitia. Ferret and mink were shown to be potential final hosts of G. nipponicum.

Animals↗
PubMed1994

Repopulation of tumour cells following irradiation with X-rays or low energy neutrons.

The repopulation of C3H mouse mammary carcinoma cells following X-ray or fast neutron irradiation was investigated in vivo using TCD50 as an endpoint. Tumours in the C3H mouse leg were irradiated in air with an X-ray dose of 9.6, 28.8 or 48.0 Gy, or a neutron dose of 2.6 or 5.2 Gy, and, various times thereafter, graded X-ray doses were given under hypoxic conditions to determine TCD50. Substantial recovery from sublethal and potentially lethal radiation damages was observed within 48 h following X-ray irradiation, and less recovery was found after neutrons. The effective number of tumourigenic cells was calculated at the time of the second irradiation using the TCD50 equation based on the multitarget model. The effective cell doubling time following X-rays depended on radiation dose. Repopulation appeared to be faster after small and intermediate X-ray doses (9.6 and 28.8 Gy) than after the largest dose, but substantial division delay was observed after the largest X-ray dose. A significant finding was that the tumour cells treated with a neutron dose, either 2.6 or 5.2 Gy, appeared to repopulate slightly more rapidly than those irradiated with X-rays, and the doubling times following two different neutron doses were not significantly different. These results suggest the use of a short overall treatment time for the high LET radiotherapy, and that caution must be exercised if the high LET radiation is given before photon doses.

Animals↗
PubMed1994

Salt sensitivity of blood pressure in patients with 17 alpha-hydroxylase deficiency.

To clarify the salt sensitivity of blood pressure in 17 alpha-hydroxylase deficiency (17 alpha-HD), a mineralocorticoid-induced hypertension, we examined the responses of blood pressure to salt loading (250 mEq/day for 6 days) after salt restriction (25 mEq/day for 3 days) in two 17 alpha-HD patients who had markedly high plasma deoxycorticosterone (DOC) (5.27 and 6.59 ng/mL; normal, 0.08 to 0.28) and corticosterone (B) (93 and 357 ng/mL; normal, 0.35 to 8.42). In case 1, moreover, the same study was repeated when plasma DOC and B restored to almost normal with the dexamethasone treatment (1 mg/day) (0.34 and 0.45 ng/mL). Salt loading elevated mean blood pressure markedly in both patients (14% and 20%), associated with cumulative sodium retention and body weight gain. Hemodynamic study showed marked increases in cardiac output (25% and 69%), but only slight decreases in systemic vascular resistance with salt loading. On the other hand, the treatment with dexamethasone could attenuate the salt-induced increase in blood pressure (2%), accompanied by lesser sodium retention, body weight gain, and elevation of cardiac output (7%) in case 1. The slope of the renal function curve for sodium excretion was decreased in these patients, and was restored toward normal by dexamethasone in case 1. We conclude that the patients with 17 alpha-HD showed salt-sensitive hypertension due to excessive DOC and B, through the impaired renal function for sodium excretion, disproportionate increase in cardiac output, and inadequate vasodilation.

Adrenal Hyperplasia, Congenital↗
PubMed1994

Involvement of the sympathetic nervous system in antihypertensive effect of cicletanine in salt-loaded young spontaneously hypertensive rats.

We examined the role of the sympathetic nervous system in the antihypertensive effect of long-term (4-week) administration of cicletanine (50 mg/100 g in diet) in young (6 week-old) spontaneously hypertensive rats (SHR) fed an 8.0% salt-containing diet. Salt loading accelerated the development of hypertension in young SHR (mean blood pressure [BP]: 158 +/- 3 v 196 +/- 5 mm Hg, P < .01). Although cicletanine did not affect mean BP in non-salt-loaded SHR, it reversed salt-induced hypertension (155 +/- 3 mm Hg, P < .01). Salt loading elevated plasma norepinephrine (NE) (246 +/- 16 v 451 +/- 87 pg/mL, P < .05) but simultaneous administration of cicletanine inhibited the increase in plasma NE with salt loading (234 +/- 12 pg/mL, P < .01). Hexamethonium, a ganglionic blocking agent, produced a greater hypotensive effect in salt-loaded than in non-salt-loaded SHR (-40 +/- 4 v -78 +/- 4 mm Hg, P < .01). In salt-loaded SHR with cicletanine, however, the hypotensive effect of hexamethonium was suppressed compared with salt-loaded SHR without cicletanine (-52 +/- 4 mm Hg, P < .01). Both plasma NE (r = 0.608, P < .01) and decrease in mean BP with hexamethonium (r = -0.798, P < .01) correlated with baseline mean BP. Thus, cicletanine inhibited the salt-induced rise in mean BP of young SHR, possibly through the suppression of enhanced sympathetic nerve activity.

Animals↗
PubMed1994

High-calcium diet prevents salt-induced hypertension and impairment of renal hemodynamics in young spontaneously hypertensive rats.

We studied the effects of a high Ca (4.07%) diet on mean arterial pressure (MAP) and renal hemodynamics in young (6 weeks) spontaneously hypertensive rats (SHR) fed a normal (0.66%) or a high-salt (8.00%) diet for 4 weeks. The high-salt diet accelerated development of hypertension (213 +/- 5 vs. 159 +/- 2 mm Hg, p < 0.01) and increased renal vascular resistance (RVR) (26.4 +/- 2.3 vs. 18.2 +/- 1.2 U, p < 0.01) in young SHR. Simultaneous Ca supplementation prevented the salt-induced increase in MAP (158 +/- 3 mm Hg, p < 0.01) and in RVR (17.3 +/- 1.1 U, p < 0.01). The high-Ca diet did not affect MAP (151 +/- 3 mm Hg, NS) and RVR (17.4 +/- 1.3 U, NS) in young SHR fed a normal salt diet. RVR and MAP were positively correlated in all rats (r = 0.634, n = 38, p < 0.001). The high-Ca diet also prevented salt-induced left ventricular (LV) hypertrophy. Dietary Ca supplementation attenuated the increased salt sensitivity of arterial pressure, possibly by normalizing renal hemodynamics, in salt-loaded young SHR.

Animals↗
PubMed1994

Long-term follow-up study of 10 adolescent patients with sleep-wake schedule disorders.

Therapeutic trials for sleep-wake schedule disorders have been described, but a long-term follow-up of adolescents with such disorders have not previously been reported. We investigated 10 adolescents with sleep-wake schedule disorders who had formerly received intensive treatment. The investigation was carried out with detailed questionnaires about current sleep conditions and social state. The follow-ups were obtained from 1.2 to 11.2 years after the initial treatment. Three cases have remitted, and six have improved in illness severity. All patients showed improvement in social adaptation. Improvement in the social adaptation level was greater than improvement in the illness severity level. More cases should be studied to learn what factors influence the prognosis of these disorders.

Adolescent↗
PubMed1994

Inhibitory effect of ammonium chloride on acetylcholine-induced relaxation.

We designed the present study to clarify whether the intracellular pH change by ammonium chloride influences endothelium-dependent relaxation in thoracic aorta of 9-week-old Sprague-Dawley rats. Intracellular alkalinization with 3 mmol/L ammonium chloride, which did not affect resting vascular tone, attenuated acetylcholine-induced relaxation but not nitroglycerin vasodilation. Acetylcholine relaxation was more inhibited by a shorter duration of treatment. Thus, change in intracellular pH may be important in the effect because the alkalinizing effect of ammonium chloride disappears gradually. In support of this, the proton ionophore nigericin abolished the effect. Also, amiloride shortened the effect of ammonium chloride, suggesting that intracellular pH plays a role: sodium-proton antiport antagonizes the disappearance of ammonium chloride-induced intracellular alkalinization. The synthesis of vasoconstrictor prostaglandins, such as thromboxane A2, may be stimulated during acetylcholine treatment, resulting in the attenuation of acetylcholine relaxation, because the relaxation was abolished by treatment with the phospholipase A2 inhibitor quinacrine, cyclooxygenase inhibitor indomethacin, prostaglandin H2/thromboxane A2 receptor antagonist S1452, and thromboxane A2 synthase inhibitor dazmegrel. Phospholipase A2 may contribute to the effect of intracellular alkalinization, which is compatible with the fact that the optimal pH of phospholipase A2 is neutral to alkaline. In addition, superoxide dismutase attenuated the effect of ammonium chloride. In conclusion, intracellular alkalinization by ammonium chloride attenuated acetylcholine-induced relaxation, possibly through the interrelated production of both thromboxane A2 and superoxide radicals.

Acetylcholine↗
PubMed1994

Effects of methamphetamine, dopamine and noradrenaline administered into the nucleus accumbens of rats discriminating subcutaneous methamphetamine.

Since the nucleus accumbens has been hypothesized to centrally mediate the discriminative effects of psychomotor stimulants, the discriminative effects of methamphetamine (MA) as well as dopamine (DA) and noradrenaline (NA) were observed by intracerebral administration of these drugs into the nucleus accumbens in rats discriminating subcutaneous MA from saline. These rats were trained and maintained to discriminate between MA at 0.5 mg/kg, s.c. and saline under a fixed ratio 10 schedule for food reinforcement in a 2-lever operant chamber situation. Guide cannulae were implanted bilaterally into the nucleus accumbens. In the substitution tests, the drug was administered into the nucleus accumbens. MA at 10 micrograms per rat substituted for subcutaneous MA in 4 out of 5 rats but neither DA at 10-40 micrograms per rat (n = 7) nor NA at 10-40 micrograms per rat (n = 4) substituted for subcutaneous MA. On the other hand, the same drugs administered into the nucleus accumbens induced increased spontaneous motor activity as also observed in six other untrained rats. MA, DA or NA alone each at 10 micrograms per rat increased spontaneous motor activity. The discriminative effects of MA are considered to be mediated in the nucleus accumbens of rats. Although DA or NA alone administered into the nucleus accumbens showed similar increasing motor activity effects as those of MA, the discriminative effects of exogenous DA or NA alone administered into the same brain area were different from those of MA in the present experimental condition.

Animals↗
PubMed1994

Molecular cloning of the gene for microbial transglutaminase from Streptoverticillium and its expression in Streptomyces lividans.

The microbial transglutaminase (TGase)-producing strains S-8112 [Agric. Biol. Chem., 53, 2613-2617 (1989)] was identified as a variant of Streptoverticillium mobaraense. We amplified a partial gene fragment by polymerase chain reaction (PCR) using oligonucleotides synthesized from the amino acid sequence of TGase, and cloned the gene for TGase using the PCR amplified fragment as a probe. The gene encoded a precursor of TGase consisting of 406 amino acid residues, which comprised the prepro region of 75 amino acid residues and the mature region of 331 amino acid residues. We expressed the TGase gene in Streptomyces lividans under a tyrosinase promoter, and found an active and mature recombinant enzyme, indicating the processing of the gene product.

Amino Acid Sequence↗
PubMed1994

Chemical synthesis of the gene for microbial transglutaminase from Streptoverticillium and its expression in Escherichia coli.

The gene coding for microbial transglutaminase (TGase) from Streptoverticillium, which consists of 331 amino acids, was chemically synthesized. The codons have been substituted for those mainly favored in yeast. Our strategy involved the construction of the TGase gene in five sections (54 oligomers) that contained unique restriction enzyme sites at both ends, which could readily be ligated to form the full-length product. The chemically synthesized gene was inserted downstream from the ompA signal peptide of the E. coli expression vector, pIN-III-ompA, which carries lpp and lac promotors. The resultant plasmid directed the expression of TGase, with the activity being secreted mainly into the periplasmic space of E. coli. The induced gene product was identical with native TGase in size and in immunological properties, though the enzyme activity was low.

Amino Acid Sequence↗
PubMed1994

Eel ventricular natriuretic peptide: isolation of a low molecular size form and characterization of plasma form by homologous radioimmunoassay.

Ventricular natriuretic peptide (VNP) with 25 amino acid residues was isolated from the low molecular weight fraction of acid extracts of eel cardiac ventricles. No other short forms of VNP were recovered from the fraction. This peptide was named eel VNP(1-25) because it was a C-terminally truncated form of the previously isolated eel VNP(1-36). As observed before with eel VNP(1-36), eel VNP(1-25) had a much higher (146-fold) vasodepressor activity than human atrial natriuretic peptide (ANP) in eels, but was a third to a half as active in rats with respect to vasodepressor and natriuretic activities. Eel VNP(1-25) was generally less potent than eel VNP(1-36) for vasodepressor and natriuretic effects. A specific radioimmunoassay (RIA) has been developed for the measurement of eel VNP. The antiserum, raised against eel VNP(1-36), was highly specific and did not exhibit significant cross-reactivity with eel ANP and C-type natriuretic peptide, even though their amino acid sequences have more than 60% homology with that of eel VNP. The sensitivity of assay was 0.5 fmol/tube for eel VNP(1-36) with more than 99% confidence. Such high sensitivity permitted direct assaying of VNP with only a few microliters of plasma. In fresh water eels, the concentration of VNP in the cardiac ventricle was higher than those in the atrium or brain and that of ANP in the ventricle. Thus, VNP seems to be a ventricular hormone. Although ANP is a major circulating hormone in mammals, the plasma concentration of VNP was threefold higher than that of ANP.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

The response of quiescent cell populations in murine solid tumors to irradiation with fast neutrons.

5-bromo-2'-deoxyuridine (BUdR) was injected into SCC VII tumor-bearing mice intraperitoneally to label all proliferating tumor cells. The mice were irradiated with fast neutrons or x-rays. Immediately, or 24 h after irradiation, the tumors were excised, minced and trypsinized. The tumor cell suspensions were incubated with cytochalasin-B (a cytokinesis blocker). The micronucleus frequency was determined using immunofluorescence staining to BUdR. The cells that were not labeled with BUdR could be regarded as the quiescent cells. The micronucleus frequency in total tumor cells was determined from the irradiated tumors that were not pretreated with BUdR. The difference in radiosensitivity between total and quiescent cells was markedly reduced with fast neutrons, especially at higher doses of radiation. Potentially lethal damage repair by total and quiescent cells was inhibited more strongly with neutrons than with x-rays. When using fast neutrons, the radiosensitivity of solid tumors depends on their heterogeneity less critically than for x-rays.

Animals↗
PubMed1994

PS-990, a novel neuritogenic compound from Acremonium sp.

A novel compound, PS-990, which induces differentiation of neuroblastoma cells, was isolated from the culture broth of a fungus, Acremonium sp. KY12702. PS-990 inhibited brain calcium calmodulin-dependent cyclic nucleotide phosphodiesterase with an IC50 value of 3 micrograms/ml, and markedly induced neurite extension of mouse neuroblastoma, Neuro2A, at concentrations ranging from 10 to 30 micrograms ml.

Acremonium↗