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Biomedical subjects

T Iida

Publications and source records attributed to T Iida.

At least 19 recordsLinked to original sources
PubMed1996

Development of an atmospheric 222Rn concentration model using a hydrodynamic meteorological model: I. One-dimensional practical model.

A one-dimensional numerical model for 222Rn transport in an atmospheric boundary layer was developed. The model consists of two parts: a prognostic hydrodynamic model including a turbulence closure model and an atmospheric diffusion model for 222Rn. The first part predicts meteorological conditions to provide the second part with vertical turbulence conditions which affects the vertical motion of 222Rn near the Earth's surface. Calculations with the model are compared with 222Rn concentrations measured during a variety of meteorological conditions, from clear days with high radiation and low winds to cloudy days of low radiation with high winds. The model's results represent well the typical diurnal variations of the 222Rn concentrations.

Air Pollutants, Radioactive↗
PubMed1995

NOC, a nitric-oxide-releasing compound, induces dose dependent apoptosis in macrophages.

The ability of exogenous nitric oxide (NO) to induce apoptosis in macrophages was analyzed using NOC, a NO-releasing compound, as a source of NO. Exogenous NO was shown to induce apoptosis in a dose dependent manner. Quantitative analysis revealed that the amount of NO required to induce apoptosis in more than half of macrophages exposed was 100 times larger than that for endogenous NO-induced apoptosis. NOC proved to be a convenient and useful tool for investigation of apoptosis related to NO.

Animals↗
PubMed1995

Structural aspects of bile acids involved in the regulation of cholesterol 7 alpha-hydroxylase and sterol 27-hydroxylase.

We have recently reported that coordinate down-regulation of cholesterol 7 alpha-hydroxylase and sterol 27-hydroxylase by bile acids results in suppression of bile acid synthesis in cultured rat hepatocytes [Twisk, J., De Wit, E. & Princen, H. M. G. (1995) Biochem. J. 305, 505-511]. In the current study, we have assessed the effects of a large group of different bile acids, both naturally occurring and synthetic, on these two key enzymes, to elucidate structural features which render bile acids potent as regulators of bile acid synthesis. Addition of 50 microM deoxycholate or cholate, two relatively hydrophobic bile acids, to the culture medium of hepatocytes resulted in strong suppression of cholesterol 7 alpha-hydroxylase (suppression of 75%) and 88%, respectively) and sterol 27-hydroxylase activity (suppression of 76% and 72%, respectively). These effects were also reflected in the mRNA levels and the transcriptional activities of the two enzymes, showing a parallel suppression of both parameters in response to cholate (suppression of 78% and 43% for cholesterol 7 alpha-hydroxylase mRNA and transcription, respectively, and suppression of 76% and 42% for sterol 27-hydroxylase mRNA and transcription, respectively). In contrast, no effects were observed with the two hydrophilic bile acids, beta-muricholate and ursocholate. Transient expression analysis in cultured rat hepatocytes, using a promoter-reporter construct containing the proximal part of the cholesterol 7 alpha-hydroxylase promoter, demonstrated a reduction of transcriptional activity by cholate (reduction of 72%), but not by ursocholate. Assessment of the effects of 27 different bile acids, varying in the number, position and orientation (alpha/beta) of hydroxyl groups on the steroid nucleus of the molecule, on cholesterol 7 alpha-hydroxylase mRNA showed only a moderate correlation with the hydrophobicity index of the bile acid involved (r = 0.61; P < 0.0001). Analysis of the three-dimensional structure of a number of these bile acids suggests that hydroxyl groups situated in close proximity to each other within the molecule, creating a hydrophilic environment, as in the case of cholate, may be a prerequisite for a strong inhibitory potency. Deviation from this situation leads to a markedly lesser effect on suppression of cholesterol 7 alpha-hydroxylase and sterol 27-hydroxylase.

Animals↗
PubMed1995

Gas chromatographic separation of bile acid 3-glucosides and 3-glucuronides without prior deconjugation on a stainless-steel capillary column.

A method for the gas chromatographic (GC) separation of the 3-glucoside and 3-glucuronide conjugates of bile acids without the necessity for a hydrolytic step is described. The bile acid glycosides were derivatized to their complete methyl ester trimethylsilyl (Me-TMS) or methyl ester dimethylethylsilyl (Me-DMES) ether derivatives, which in turn were chromatographed on an inert and thermostable stainless-steel capillary column, Ultra ALLOY-1 (HT), coated with a thin film (0.15 micron) of chemically bonded and cross-linked dimethylsiloxane. They exhibited a single peak of the theoretical shape without any accompanying peaks due to thermal decomposition, even at oven temperatures of 320-330 degrees C. Excellent GC separation of isomeric bile acid glycosides was achieved by the combined use of suitable derivatives and column. This method, which does not need the prior deconjugation of the glycosidic moiety, could be usefully applied to biosynthetic and metabolic studies of bile acids in biological materials.

Bile Acids and Salts↗
PubMed1995

Effects of endothelin-1 on Ca2+ signaling and secretion in parathyroid cells.

It has been previously reported that parathyroid cells express endothelin (ET) receptors and secrete ET-1 in an extracellular Ca2+ concentration ([Ca2+]e)-dependent manner. Here, we examined the effects of ET-1 on intracellular signaling and parathyroid hormone (PTH) secretion in dispersed bovine parathyroid (bPT) cells, which comprise several cell types including epithelial and endothelial cells, in two cell lines, the rat parathyroid epithelial (PT-r) and the bovine parathyroid endothelial (BPE-1) cells. An RNA-polymerase chain reaction analysis revealed that both ETA and ETB receptors are expressed in bovine parathyroid tissue and BPE-1 cells, and only the ETA receptor is expressed in PT-r cells. PT-r cells also expressed an inositol 1,4,5-trisphosphate (Ins[1,4,5]P3) receptor, and ionomycin induced an increase in the intracellular Ca2+ concentrations ([Ca2+]i) in a Ca(2+)-deficient medium, indicating the presence of an operative intracellular Ca2+ pool in these cells. In cells bathed in 1 mM [Ca2+]e, ET-1 induced a rapid and transient increase in the Ins(1,4,5)P3 production, which was associated with a similar profile of increase in [Ca2+]i and with a peak response of about 800 nM. No changes in the profile of [Ca2+]i responses were observed in ET-1-stimulated cells in the presence of Ca2+ channel blockers, or in Ca(2+)-deficient medium, indicating that Ca2+ mobilization was not associated with Ca2+ entry. Furthermore, a sustained stimulation with ET-1 induced a decrease in [Ca2+]i below the prestimulatory level in a large population of cells, and the percentage of the cell population that shows the sustained decrease of [Ca2+]i increased in higher ET-1 concentrations. [Ca2+]i in PT-r cells was also controlled by a [Ca2+]e-dependent mechanism that changed [Ca2+]i from 28 to 506 nM in a 0.1-3 mM concentration range with an EC50 of 1.2 mM, which is comparable to that reported for bPT cells. In the same range of [Ca2+]e, PTH secretion from bPT cells was inhibited with an IC50 of 1 mM, and ET-1 increased PTH release in a dose-dependent manner but without affecting the IC50 for the [Ca2+]e-dependent inhibition. Thus, the parathyroid epithelial cells appear to respond to ET-1 in a unique way, and the ET autocrine system can be regarded as a possible mechanism to modulate the sensitivity of [Ca2+]e-dependent PTH release.

Animals↗
PubMed1995

Isolation of mutant toxins of Vibrio parahaemolyticus hemolysin by in vitro mutagenesis.

Thermostable direct hemolysin produced by Vibrio parahaemolyticus is a major virulence factor of the organism. The hemolysin has a variety of biological activities such as lethality to mice, cytotoxicity to cultured cells, cardiotoxicity, and fluid accumulating activity in rabbit ileal loop test. In this study, we attempted to isolate less hemolytic mutant toxins of the thermostable direct hemolysin to use them for analysis of mode of action of the hemolysin. Six mutant toxins were obtained by in vitro mutagenesis of the cloned gene for the hemolysin. Characterization of the mutant toxins demonstrated that single amino acid substitutions at Gly62, Trp65, Thr67, Gly86, Glu116 and Glu138 resulted in a loss or lowering of the hemolytic activity. Two of the mutant toxins inhibited hemolysis by wild-type toxin on rabbit blood agar plates, while their hemolytic activity was below the detectable level. These mutant toxins would be useful for identifying the as yet unknown receptor for the hemolysin on the target cell membrane.

Bacterial Toxins↗
PubMed1995

Urease production correlates with possession of the trh gene in Vibrio parahaemolyticus strains isolated in Thailand.

A total of 489 Vibrio parahaemolyticus isolates from patients in Thailand with diarrhea was examined for the presence of thermostable direct hemolysin (TDH) and TDH-related hemolysin genes (tdh and trh, respectively), their serovars, TDH production, and urease activity. Of the strains, 81% were positive only for the tdh gene, 6% for both trh and tdh genes, and 2% for the trh gene only. Thirty-seven (8%) of the 489 isolates were positive for urease production. Of special interest, all urease-positive strains possessed the trh gene, and conversely, urease-negative strains lacked the gene, indicating that urease production by V. parahaemolyticus strains strongly correlates with the possession of the trh gene. Thus, the urease-positive phenotype of V. parahaemolyticus can be considered an indication of virulent (trh-possessing) V. parahaemolyticus strains in clinical diagnosis.

Bacterial Proteins↗
PubMed1995

Measurements of thoron progeny concentration using a potential alpha-energy monitor in Japan.

It is reported that thoron concentration in Japanese dwellings may be higher than in other dwellings. Therefore, in order to assess the risk for indoor thoron progeny, the portable potential alpha-energy monitor has been developed. The monitor detects alpha-particles from the 212Po collected on the filter using a piece of cellulose nitrate film. The detection efficiency of the alpha-particles has been estimated by Monte Carlo calculation. From the results of measurements, the mean indoor thoron progeny concentration in the dwellings was 1.5 Bq m-3 (ECTn), and ranged from 0.04 to 8.2 Bq m-3. The effects of three typical interior walls (soil-based plaster, concrete, and modern materials) on the thoron progeny supply were considered. The mean annual effective dose equivalent was 0.45 mSv.

Air Pollutants, Radioactive↗
PubMed1995

Some problems on the measurement of 222Rn concentrations by passive cup method.

A passive cup monitor has been constructed by using a 50 mm radius stainless steel hemisphere. The conductive housing has reduced the scatter in track densities. In dwellings with high 220Rn concentrations, it is particularly necessary to measure 222Rn concentration with a monitor having a radon exchange rate less than 0.1 h-1.

Radiation Monitoring↗
PubMed1995

Changes in the E/A ratio induced by handgrip-exercise are related to changes in the plasma atrial natriuretic peptide level, but not to changes in brain natriuretic peptide in mild essential hypertension.

We investigated the relationship between changes in atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) and changes in cardiac function during mild exercise in patients with mild hypertension. The handgrip test (HGT) was performed by 21 untreated, mildly hypertensive patients, mean age 45 +/- 5 years. M-mode and pulse Doppler echocardiograms were recorded before and during HGT. In 7 patients (Group A), diastolic function, which was determined by the peak early velocity and peak atrial velocity (E/A) ratio using Doppler echocardiography was attenuated during HGT (1.19 +/- 0.21 TO 1.04 +/- 0.16, p < 0.05). There was no change in diastolic function in the remaining 14 patients, left atrial diameter, cardiac index, ejection fraction, plasma renin activity, plasma norepinephrine, blood pressure, nor heart rate were different between the two groups. While ANP was increased in Group A during HGT (from 41.0 +/- 18.2 to 54.0 +/- 24.1 pg/ml, p < 0.05) it was unchanged in Group B (36.8 +/- 16.3 to 33.5 +/- 11.9 pg/ml). BNP did not change in either Group (Group A: 2.9 +/- 3.1 to 3.0 +/- 3.4 pg/ml, Group B: 2.6 +/- 1.6 to 3.6 +/- 4.8 pg/ml). The percent change in ANP during HGT did not correlate with the percent change in BNP. Thus, the impairment of cardiac functional reserve appeared to influence ANP excretion in patients with mild hypertension.

Adult↗
PubMed1995

Molecular epidemiology of Vibrio cholerae O1 isolated in Nepal by southern hybridization with a cholera toxin gene probe.

A cholera epidemic broke out in 1992 due to Vibrio cholerae O1 biotype El Tor in the eastern and southern belt of Nepal mainly among the Bhutanese refugees. Restriction fragment profiles (RFP) of DNA fragments of V. cholerae O1 isolates hybridized with an enzyme-labelled oligonucleotide probe for cholera toxin gene (ctx) by Southern Hybridization were compared. The probe hybridized with the 13- and 8-kb fragments of PstI-digested total DNA in all isolates observed in the epidemic. This RFP in the Nepalese strain was not observed in the strains isolated during other epidemics but was observed in the strains isolated from the exported marine products from Taiwan and Thailand.

Blotting, Southern↗
PubMed1995

[Effect of 5'-deoxy-5-fluorouridine (5'-DFUR) on the activity of pyrimidine nucleoside phosphorylase (pyNPase) in normal and tumor tissues of human stomach].

PyNPase (pyrimidine nucleoside phosphorylase) activity and IL-1 alpha were measured in normal and tumor tissues of the specimens resected from gastric cancer patients who had been divided into two groups; one given preoperative 5'-DFUR (oral administration at a mean dose of 10.0 g) and one not given 5'-DFUR (control). PyNPase activities in both groups were higher in tumor than in normal tissues (p = 0.0001), but, less in tumor tissue of the preoperative administration group than the controls (p = 0.0376). IL-1 alpha levels in both groups were higher in tumor than in normal tissues (p < 0.01). Multiple regression analysis of the results showed that IL-1 alpha strongly influenced on PyNPase activity in tumor tissues (higher IL-1 alpha levels resulted in higher PyNPase activities in tumor tissues) (p = 0.0334).

Antineoplastic Agents↗
PubMed1995

[Binding of PCB by several types of dietary fiber in vivo and in vitro].

We investigated the binding of PCB by dietary fiber in vivo and in vitro. Forty male rats consisting of four rats a group were housed and rats of each group were given a treatment diet containing rice-bran fiber, spinach fiber, burdock fiber, cabbage fiber, soybean fiber Japanese-radish fiber, carrot fiber, corn fiber and cellulose for five days. The remaining four rats were fed a non-fiber diet as controls. The animals were administered with 0.5 ml of the race-bran oil used by Yusho patients and kept on the same diets for five days. Fecal excretion of PCB in the group fed rice-bran fiber and spinach fiber was significantly (p < 0.01) stimulated 6.6 and 4.1 times, respectively, as compared with controls. Dietary fiber was suspended in distilled water, and methanolic solution of PCB was added to these suspensions. The mixtures were then incubated. After centrifugation, the unbound PCB in supernatant was analyzed by gas chromatograph. Rice-bran fiber and spinach fiber bount more PCB than any of the other dietary fiber. A significant correlation existed between the amounts of binding PCB in vitro and fecal PCB output in rats by eight types of dietary fiber (r = 0.986, p < 0.01).

Adsorption↗
PubMed1995

[Effect of dietary fiber on fecal excretion and liver distribution of PCDF in rats].

Forty male rats (126 g body weight) consisting of four rats a group were housed and rats of each group were given a treatment diets containing cellulose, rice-bran fiber, spinach fiber, burdock fiber, cabbage fiber, soybean fiber, Japanese-radish fiber, carrot fiber and corn fiber for five days. The remaining four rats were fed a non-fiber diet as controls. The animals were orally administered with 0.5 ml of the rice-bran oil used by Yusho patients and kept on the same diets for five days. The rice-bran oil was contaminated with 2, 3, 7, 8-tetrachlorodibenzofuran (2, 3, 7, 8-T4CDF, 458.7 ng/ml), 2, 3, 4, 7, 8-pentachlorodibenzofuran (2, 3, 4, 7, 8-P5CDF, 802.4 ng/ml) and 1, 2, 3, 4, 7, 8-hexachlorodibenzofuran (1, 2, 3, 4, 7, 8-H6CDF, 752.3 ng/ml). PCDF in feces and liver were analyzed by high resolution gas chromatography-mass spectrometry. The fecal excretion of 2, 3, 7, 8-T4CDF in the group fed rice-bran fiber and spinach fiber was significantly (p < 0.01) stimulated 11.3 and 6.8 times, respectively, as compared with controls. Moreover, 2, 3, 4, 7, 8-P5CDF and 1, 2, 3, 4, 7, 8-H6CDF were excreted in stool at the rate of 4.1 and 3.4 times, respectively and 2.1 and 2.2 times, respectively, as compared with controls. These results suggest that administration of dietary fiber is useful for a new approach to therapy of Yusho patients.

Animals↗
PubMed1995

Clinical trial of a combination of rice bran fiber and cholestyramine for promotion of fecal excretion of retained polychlorinated dibenzofuran and polychlorinated biphenyl in Yu-Cheng patients.

A clinical trial using the combination of rice bran fiber (RBF) and cholestyramine (CHO) was carried out on Yu-Cheng patients in 1993-1994. By the analysis of blood and stool samples collected from the patients before and after (or during in the case of stool), it was verified that the administration of RBF and CHO is effective for excretion of polychlorinated biphenyl (PCB) (p < 0.05) and polychlorinated dibenzofuran (PCDF), especially 2, 3, 4, 7, 8-pentachlorodibenzofuran (p < 0.05). However, the degree of effectiveness varied upon individual patients from 60 to 160% for 2, 3, 4, 7, 8-pentachlorodibenzofuran, from 30 to 110% for 1, 2, 3, 4, 7, 8-hexachlorodibenzofuran and from 50 to 190% for PCB, respectively.

Benzofurans↗
PubMed1995

[Levels of PCDDs, PCDFs and coplanar PCBs in the blood and stool of Taiwanese Yu-Cheng patients].

Levels of PCDDs, PCDFs and coplanar PCBs were measured in the blood and stool obtained from seventeen patients with Yu-Cheng in Taiwan. The average total concentrations of PCDDs, PCDFs and coplanar PCBs in the blood collected from Yu-Cheng patients in January 1993 and August 1994 were 590 and 570 pg Toxic Equivalents (TEQs)/g lipid, respectively. The concentrations of PCDDs, PCDFs and coplanar PCBs in the blood of patients were 21, 540 and 10 pg TEQs/g fat, respectively. On the other hand, the fecal excretion of PCDDs, PCDFs and coplanar PCBs were 26, 720 and 15 pg TEQs/day, respectively. The composition of congeners in the feces was quite similar to the one in the blood. The half lives were estimated as 9.1 and 8.6 years for 2, 3, 4, 7, 8-pentachlorodibenzofuran and 1, 2, 3, 4, 7, 8-hexachlorodibenzofuran based on fecal excretion, respectively.

Asian People↗
PubMed1995

[Study of choroidal vascular lesions in bullous retinal detachment by indocyanine green angiography].

Fluorescein and indocyanine green (ICG) angiography was performed in 18 eyes of 9 patients with bullous retinal detachment. The series comprised 12 eyes with retinal detachment, 3 treated eyes and 3 unaffected eyes. In the 12 eyes with retinal detachment, there were a total of 33 sites of fluorescein leakage, or 2.8 per eye. Leakage of ICG into the subretinal space, corresponding to the site of leakage of fluorescein, was present at 29 foci in 12 eyes. A dilated major choroidal vein was located posterior or adjacent to the site of leakage. Choroidal tissue staining was present around 30 foci of leakage in 12 eyes in late-phase ICG angiograms. This phenomenon persisted after serous retinal detachment had disappeared following photocoagulation. Multiple areas of choroidal staining were also present in unaffected areas in all the 12 eyes. Choroidal staining was also a regular feature around retinal pigment epithelial detachment. Recurrence of leakage developed in this area in one eye. The findings suggest that choroidal vascular hyperpermeability plays a causative role in damage to the retinal pigment epithelium in bullous retinal detachment.

Adult↗