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Biomedical subjects

T Iida

Publications and source records attributed to T Iida.

At least 325 records · Page 18Linked to original sources
PubMed1991

Lack of induction of hepatic DNA damage on long-term administration of peroxisome proliferators in male F-344 rats.

In order to evaluate the relationship between hydrogen peroxide (H2O2) generation and subsequent DNA damage caused by peroxisome proliferation, we examined DNA damage and changes in peroxisomal beta-oxidation activity in rat liver. Male F-344 rats were given orally clofibrate, bezafibrate or di(2-ethylhexyl)phthalate (DEHP) for up to 78 weeks. In rats fed DEHP for 52 or 78 weeks hepatocarcinomas or neoplastic nodules were found. In rats treated for 2 weeks with peroxisome proliferators, peroxisomal beta-oxidation activity was increased 10-17 times over control levels. After long-term treatment (20-78 weeks), the level of peroxisomal beta-oxidation activity remained 3-13-times higher in each group. When single strand DNA breaks were measured by a DNA-alkaline elution technique, no increase in DNA damage was observed in livers from rats fed peroxisome proliferators for 2, 40 or 78 weeks. In rats bearing hepatocarcinomas induced by DEHP, the hepatic DNA showed significant breaks; the rate of DNA-alkaline elution was found to increase approximately 5-fold. No significant increase in hepatic lipid peroxide level was observed in each group. These results show that although prolonged treatment with peroxisome proliferators induces markedly peroxisomal beta-oxidation activity, the active oxygen species from peroxisomal beta-oxidation are not enough to give rise to significant DNA damage. Moreover, the change in the activity of peroxisomal beta-oxidation may not relate to hepatocarcinogenesis induced by peroxisome proliferators.

Animals↗
PubMed1991

Antibasement membrane zone antibodies in localized pretibial pemphigoid.

To clarify the nosologic position of localized pretibial pemphigoid, Western immunoblotting analysis was carried out using the sodium dodecyl sulfate extracts of normal human epidermis. Sera from patients with localized pretibial pemphigoid and generalized bullous pemphigoid reacted with 220- to 240-kd polypeptide, which is a critical point for a definite diagnosis of bullous pemphigoid. This result suggests that localized pretibial pemphigoid belongs to the same nosologic position as bullous pemphigoid.

Aged↗
PubMed1991

Prenatal diagnosis of rubella infection by fetal blood sampling.

Prenatal diagnosis of rubella infection was attempted at 21 to 23 weeks of gestation by measuring rubella-specific IgM by ELISA in blood obtained from 16 fetuses whose mothers had been confirmed rubella infection during pregnancy. Specific IgM was detected in 9 fetuses. In 1 case, the time of the appearance of the rash was 20 weeks of gestation and this pregnancy went to term resulting in a healthy baby without clinical evidence of congenital rubella. The remaining 8 patients had their pregnancies terminated, and fetal infection was confirmed by blood tests after the abortion. No specific IgM was detected in the 7 other fetuses. However, in 2 IgM fetal blood negative cases whose mothers had had the rash at 17 and 20 weeks of gestation, the neonates showed positive IgM findings, but were apparently healthy. The reasons for the false-negative findings are discussed.

Adult↗
PubMed1991

Typing of human polyomavirus JC virus on the basis of restriction fragment length polymorphisms.

JC virus DNA clones from the urine of nonimmunosuppressed Japanese individuals regularly contain an archetypal regulatory sequence which may have generated various regulatory sequences of JC virus isolates from patients with progressive multifocal leukoencephalopathy (PML). In this study, we established 15 new clones from the urine of Dutch, German, and Taiwanese healthy volunteers and patients. Most of these clones contained regulatory sequences essentially identical to the archetypal regulatory sequence. These clones, along with two representative urine-derived clones in Japan and five clones from the brains of PML patients (four established in the United States and one established in Japan), were analyzed with a number of restriction enzymes. We found nine restriction fragment length polymorphisms by which all clones were classified into either of the two types, A and B. Type A contained only clones from the West, while type B contained some from the West and all from eastern Asia. Each type contained both urine-derived and PML-derived clones. Furthermore, there was a close relationship between some urine-derived clones and some PML-derived clones in restriction site mapping analysis. These findings support the adaptation hypothesis which has been postulated to explain the genesis of PML-type JC viruses.

Base Sequence↗
PubMed1991

Sequence rearrangement in JC virus DNAs molecularly cloned from immunosuppressed renal transplant patients.

From nonimmunocompromised individuals, we have recently identified a possible archetypal JC virus DNA sequence from which various regulatory sequences of JC virus isolates derived from patients with progressive multifocal leukoencephalopathy (PML) could have evolved. In this study, we analyzed the regulatory sequences of JCV DNAs cloned from urine samples of a PML risk group (renal transplant patients on immunosuppressive therapy). A number of JC virus DNAs were molecularly cloned from virions excreted in the urine of eight patients. Furthermore, fragments containing the regulatory region were amplified by the polymerase chain reaction and subsequently molecularly cloned from cell-associated JC virus excreted in the urine of two patients. The regulatory regions in all clones were analyzed with restriction enzymes, and those in representative clones were sequenced. We found that clones with the archetypal regulatory sequence were predominant in all urine samples, but a few clones carried regulatory sequences that diverged from the archetypal sequence by deletion or duplication. The finding that sequence rearrangement in the archetypal regulatory region occurs in the course of infection in immunosuppressed hosts is consistent with the adaptation hypothesis which has been put forward to explain the divergence of the regulatory regions in PML-derived JC virus isolates.

Base Sequence↗
PubMed1991

Dominance of blood pressure in natriuresis associated with supraventricular tachycardia.

Supraventricular tachycardia was induced in 10 patients by programmed cardiac stimulation through esophageal lead. Blood pressure, heart rate, renal function, and hormonal factors were measured before, during, and after tachycardia. The patients were divided into two groups, depending on whether antinatriuresis occurred during tachycardia; one group (n = 5) with antinatriuresis during tachycardia associated with a decrease in blood pressure and the other group (n = 5) with neither antinatriuresis nor changes in blood pressure. The urinary sodium excretion tended to increase after tachycardia only in the latter group. On the other hand, urine volume and free water clearance increased during or after tachycardia in both groups. Plasma levels of atrial natriuretic peptide significantly increased and the urinary vasopressin excretion significantly decreased during tachycardia in both groups. During tachycardia, natriuresis due to atrial natriuretic peptide secretion seems to be hampered by hypotension, but polyuria is preserved despite the fall in blood pressure probably related to suppression of vasopressin release.

Adult↗
PubMed1991

Spontaneous and agonist-induced calcium oscillations in pituitary gonadotrophs.

Basal and receptor-regulated changes in cytoplasmic calcium concentration ([Ca2+]i) were monitored by fluorescence analysis in individual rat pituitary gonadotrophs loaded with the calcium-sensitive dye indo-1. Most gonadotrophs exhibited low amplitude spontaneous oscillations in basal [Ca2+]i that were interspersed by quiescent periods and abolished by removal of extracellular Ca2+ or addition of calcium channel blockers. Such random fluctuations in [Ca2+]i, which reflect the operation of a plasma membrane oscillator, were not coupled to basal gonadotropin secretion. The physiological agonist GnRH induced high amplitude [Ca2+]i oscillations; when a threshold [Ca2+]i level was reached, a cytoplasmic oscillator began to generate extremely regular Ca2+ transients. The time required to reach the threshold [Ca2+]i level was inversely correlated with agonist dose; the frequency, but not the amplitude, of agonist-induced Ca2+ spiking increased with agonist concentration. The duration of the latent period decreased and the frequency of Ca2+ spiking increased with the increase in ambient temperature. At high GnRH concentrations, the calcium transients merged into biphasic responses similar to those observed in cell suspensions at all GnRH concentrations. The presence of spontaneous fluctuations in basal [Ca2+]i did not significantly change the patterns of agonist-induced [Ca2+]i responses. Also, removal of extracellular Ca2+ did not interfere with the frequency or amplitude of Ca2+ spikes, but caused the loss of the plateau phase. Blockade of intracellular Ca(2+)-ATPase pumps by thapsigargin was usually accompanied by a subthreshold increase in [Ca2+]i. In such cells the agonist-induced oscillatory pattern was transformed into the biphasic response. In about 10% of the cells, however, high thapsigargin concentrations induced coarse [Ca2+]i oscillations; subsequent stimulation of such cells with GnRH was ineffective. The cytoplasmic oscillatory and biphasic responses may represent a mechanism for differential activation of Ca(2+)-dependent enzymes and their dependent cellular processes, including hormone secretion. The membrane oscillator is probably responsible for refilling of agonist-sensitive pools during and after agonist stimulation.

Animals↗
PubMed1991

Prevalence of Listeria monocytogenes in intestinal contents of healthy animals in Japan.

A total of 1,705 fecal specimens or ileo-cecal contents of cattle, pigs, dogs, cats, chicken and rats were submitted for the isolation of Listeria monocytogenes by the use of the combination of Oxford-LPM agar plates after the cold enrichment in PBS at 4 degrees C for 4-6 weeks. Prevalence of L. monocytogenes was found to be 1.9% in cattle, 0.6% in pigs, 0.9% in dogs and 6.5% in rats. However, none of L. monocytogenes was isolated from chicken or cats. Among 26 isolates of L. monocytogenes, 13 strains (50%) were classified into types 1/2a (3 strains), 1/2b (5 strains) and 4b (5 strains) and were often associated with human listeriosis. The majority of the Listeria spp. other than L. monocytogenes isolated from these animals was found to be L. innocua.

Animals↗
PubMed1991

[Interrelation of tooth crown diameters].

The purpose of this study was to clarify the interrelation of the tooth crown diameters using statistical methods. The material consisted of 414 dental casts from orthodontic patients in the Japanese female. The mesiodistal diameters of all permanent teeth on the left side were measured, excluding the third molars. These values were examined by correlation coefficient matrix and multivariate analyses such as multiple regression, principal component and canonical correlation, etc. The results were as follows: 1) The tooth crown diameters showed a strong intercorrelation within each jaw and between both jaws. 2) When the incisors and the canine were large in size, the premolars and the molars tended to be small. 3) When the incisors and the molars were large in size, the canine and the premolars tended to be small. 4) When the incisors and the premolars were large in size, the canine and the molars tended to be small. 5) All of the teeth except the upper lateral incisor were classified according to size into the four groups of incisors, canines, premolars and molars. 6) The dentition with small teeth tended to show a spaced arch.

Crowns↗
PubMed1991

Calcium signaling and secretory responses in endothelin-stimulated anterior pituitary cells.

Endothelin (ET) receptors are present in pituitary cells and stimulate hormone release through the phosphoinositide/Ca2+ signaling system. In pituitary cell suspensions, ET caused [Ca2+]i elevations of much higher amplitudes than those induced by other vasoactive hormones, including angiotensin II, vasopressin, and noradrenalin. The action of ET was coupled to rapid and transient activation of exocytosis in gonadotrophs, thyrotrophs, somatotrophs, and lactotrophs. In contrast, angiotensin II did not stimulate luteinizing hormone release, and luteinizing hormone responses to vasopressin and noradrenalin were very small. Single gonadotrophs exhibited three types of [Ca2+]i responses to increasing doses of ET, (a) subthreshold responses, with amplitude modulation; (b) threshold-oscillatory responses, with frequency modulation; and (c) threshold-biphasic responses, as the summation of single Ca2+ spikes. The same [Ca2+]i patterns were also seen in gonadotropin-releasing hormone (GnRH)-stimulated cells. In the presence of [Ca2+]e, the amplitudes of the Ca2+ spikes progressively decreased during continuous stimulation with ET or GnRH, reaching the nonoscillatory plateau level after 200-400 sec of stimulation. In cells stimulated with GnRH, subsequent exposure to ET, GnRH, or ionomycin during the plateau phase did not elicit further increases in [Ca2+]i, whereas cells stimulated with ET responded partially to all three agents. In addition, cells exposed to ET or GnRH for 30 min, followed by a 30-min recovery period, were able to mount a full [Ca2+]i response to GnRH, but not to ET-1. Similarly, both peptides elicited rapid increases in LH release, with comparable potencies, but the response to ET decreased much more rapidly during sustained stimulation and gonadotrophs became refractory to further ET stimulation. This is in part attributable to rapid endocytosis of ET receptors during continuous agonist stimulation. These data indicate that ET exerts potent but transient secretory actions in several pituitary cell types and is a potential regulator of gonadotropin release. The initial receptor-coupling events in both ET- and GnRH-stimulated cells are similar, but the differences observed during continuous or repetitive stimulation indicate that the ET receptor pathway undergoes rapid desensitization that is critical in determining the distinct cellular responses to the two peptides.

Angiotensin II↗
PubMed1991

Potential bile acid metabolites. XVIII. Synthesis of stereoisomeric 3,6,12 alpha-trihydroxy-5 beta-cholanoic acids.

Two new 6-hydroxylated bile acids, 3 beta, 6 alpha, 12 alpha- and 3 beta, 6 beta, 12 alpha-trihydroxy-5 beta-cholanoic acids, were synthesized from deoxycholic acid. In addition, their C-3 epimers, 3 alpha, 6 alpha, 12 alpha- and 3 alpha, 6 beta, 12 alpha-trihydroxy acids, were prepared by a new route. The principal reactions used were 1) 6 beta-hydroxylation of 3-methoxy-3,5-dienes with m-chloroperbenzoic acid in aqueous dioxane; 2) catalytic hydrogenation of the resulting 6 beta-hydroxy-3-oxo-4-enes to the 6 beta-hydroxy-3-oxo-5 beta compounds with palladium on calcium carbonate catalyst in ethanol; and 3) stereoselective reduction of appropriate 3-oxo derivatives with potassium tri-sec-butylborohydride and tert-butylamine-borane complex. The thin-layer chromatographic, gas-liquid chromatographic, and high performance liquid chromatographic mobilities, and 1H- and 13C-nuclear magnetic resonance spectroscopic data of the four stereoisomers are presented. With this work all the 6-hydroxylated derivatives of lithocholic, deoxycholic, chenodeoxycholic, ursodeoxycholic, and cholic acids in the 5 beta series are now known and have been synthesized.

Bile Acids and Salts↗
PubMed1991

[Morphology of live retinal pigment epithelial cells].

We attempted to observe, by means of fluorescein angiography, the retinal pigment epithelial cells in pigmented rabbits. Fluorescein angiography was performed in 31 pigmented rabbits, after intravenous injection of 14mg/kg fluorescein sodium. The angiograms were evaluated as prints and as negative film under a light microscope. Animals were sacrificed and submitted to studies by scanning electron microscopy and fluorescein light microscopy. On fluorescein angiograms, we observed mosaic pattern which consisted of numerous polygonal spots overlying choroidal vasculature. Each polygonal spot showed central hypofluorescent area surrounded by hyperfluorescent rim. They were seen in all the eyes except 4 lightly pigmented eyes. They seemed to correspond, in size, to each retinal pigment epithelial cell. This pattern appeared from the early choroidal phase on, to become more distinct 5 to 15 minutes after dye injection. A hexagonal pattern was regularly seen away from the medullary rays by 3 or more disc diameters. The pattern became larger in the periphery than in the posterior pole. These angiographic findings closely matched those of retinal pigment epithelial cells as seen by scanning electron microscopy and fluorescein light microscopy in sizes and shapes. The findings indicate that it is possible to identify retinal pigment epithelial cells in pigmented rabbits by conventional fluorescein angiography.

Animals↗
PubMed1991

[The effect of organochlorine compounds on the induction of sister chromatid exchanges in cultured human lymphocytes].

In this study, first, we investigated the effect of 7,8-benzoflavone (ANF), mitomycin C (MMC), a well-known genotoxic compound, and ANF plus MMC on the induction of sister chromatid exchanges (SCEs) in human whole-blood cultures. Second, we examined the effect of mixture of organochlorine compounds, which very resembled their contamination of healthy people in its composition, on the induction of SCEs in the same blood culture system in order to clarify their genotoxicity as a whole. The following results were obtained. 1. ANF and MMC significantly enhanced the number of SCEs/cell at the concentrations of 4 x 10(-5) M and 10(-8)M, respectively. When both of the compounds were simultaneously added in the blood cultures, their effects on the induction of SCEs seemed to be additive. 2. Without ANF in the blood culture system, namely, an usual system of the SCEs experiment, we could not find a dose-response relationship between the concentration of the mixture of organochlorine compounds and the induction of SCEs/cell. With ANF, however, we observed a fairly good dose-response relationship between them. 3. In the whole-blood culture system with ANF, we found significantly great number of SCEs/cell at the level of twenty times higher concentration of the organochlorine compounds than the ordinary level. According to the results described above and of our other studies, 50% effective concentration (EC50, about 2 SCEs/cell higher than control SCEs/cell) of the mixture was considered to be about 5 times greater level over the general one.(ABSTRACT TRUNCATED AT 250 WORDS)

Benzofurans↗
PubMed1991

[Coplanar PCBs, PCDFs and PCDDs in the subcutaneous adipose tissue of Yusho patients and normal controls].

3,4,3',4'-tetrachlorobiphenyl (T4CB), 3,4,5,3',4'-pentachlorobiphenyl (P5CB) and 3,4,5,3',4',5'-hexachlorobiphenyl (H6CB) [Co-PCBs] in the subcutaneous adipose tissue of seven Yusho patients and eight normal controls were determined to assess the contribution in the risk caused by the Yusho causual agents (PCBs, PCDFs, PCDDs and Co-PCBs) by using high resolution gas chromatography/high resolution mass spectrometry in selected ion monitoring mode. 3,4,3',4'-T4CB, 3,4,5,3',4'-P5CB and 3,4,5,3',4',5'-H6CB were detected in the subcutaneous adipose tissue of the Yusho patients at the levels, of 6 to 29 ppt, of 32 to 130 ppt and of 160 to 1,140 ppt, respectively. The TCDD-Eq (Equivalents) value calculated by TCDD-TEfs (Toxic Equivalent factors) was from 8 to 30 ppt. On the other hand, 3,4,3',4'-T4CB, 3,4,5,3',4'-P5CB and 3,4,5,3',4',5'-H6CB were detected in the subcutaneous adipose tissue of normal controls at the levels, of 3 to 9 ppt, of 41 to 280 ppt and of 47 to 200 ppt, respectively. The TCDD-Eq value calculated by TCDD-TEfs was from 9 to 57 ppt. In the Yusho patients, the average TCDD-Eq value calculated by TCDD-TEfs of the residual Co-PCBs, PCDFs and PCDDs was 17, 491 and 24 ppt, respectively. Therefore, we concluded that the typical symptoms for the Yusho patients are caused mostly by PCDFs.

Adipose Tissue↗
PubMed1991

[Therapeutic trial for promotion of fecal excretion of PCDFs and PCBs by the administration of cholestyramine in Yusho patients].

Any effective therapy for elimination of causal agents remaining in Yusho patients was not found until now. To know the profile of fecal excretion of polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs), the amounts of PCDFs and PCBs in the stool of six Yusho patients with the typical symptoms were determined. The stool samples of Yusho patients were collected in 1989. PCDFs, i.e., 2,3,7,8-tetrachlorodibenzofuran (TCDF), 2,3,4,7,8-pentachlorodibenzofuran (PnCDF), 1,2,3,4,7,8- and 1,2,3,6,7,8-hexachlorodibenzofurans (HxCDFs), 1,2,3,4,6,7,8-heptachlorodibenzofuran (HpCDF) and octachlorodibenzofuran (OCDF) were detected in all of the samples. PCDFs found in the stool samples were mostly PnCDF and HxCDFs. Of PCDFs detected, PnCDF and HxCDFs contributed to 42 +/- 4.7% and 43 +/- 5.5% as mean +/- SE, respectively. The fecal excretion of PnCDF and HxCDFs in Yusho patients was 720 +/- 490 pg/day and 790 +/- 620 pg/day as mean +/- SE, respectively. On the other hand, the fecal excretion of PnCDF and HxCDFs in normal controls was 32 +/- 13 pg/day and 47 +/- 5.2 pg/day as mean +/- SE, respectively. The fecal excretion of PnCDF and HxCDFs in Yusho patients was about 23 times and 17 times each higher than that in normal controls. The fecal excretion of PCBs in Yusho patients and normal controls was 400 +/- 430 ng/day and 150 +/- 39 ng/day, respectively, as mean +/- SE. In order to promote the excretion of these toxic chemicals in the stool of Yusho patients, the patients were continuously administered with cholestyramine, an anion exchange resin, at a dose of 4 g, 3 times a day, for 6 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Benzofurans↗