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Biomedical subjects

Mitsuru Shimizu

Publications and source records attributed to Mitsuru Shimizu.

10 recordsLinked to original sources
PubMed2006

Immunomodulatory effects of mono-, di-, and trimethylphenols in mice.

The relationship of air pollutants with the increasing prevalence of allergic diseases is a matter of concern in developed countries. In this study, the immunomodulatory effects of mono-, di-, and trimethylphenols in mice were examined as regards two aspects. First, whether or not these chemicals act as sensitizers was evaluated by local lymph node assay. Of the 13 methylphenols tested, three dimethylphenol isomers (2,4-DMP, 2,5-DMP, and 3,4-DMP) were found to induce auricular lymphocyte proliferation after dermal application on both ears of mice. Cytokine production patterns in the supernatants of cultured auricular lymphocytes from mice showed these methylphenols to be contact sensitizers. Second, the effects of methylphenols on cytokine production profiles were examined using cultured splenocytes from immunologically naive mice. Under subtoxic conditions, eight methylphenols inhibited interferon-gamma (IFN-gamma) production significantly, while the effect on intreluekin-4 (IL-4) production was moderate, resulting in higher IL-4/IFN-gamma ratios in all of the tested chemicals, with the most prominent effect shown by 2,6-DMP. These results suggest that several methylphenols, especially dimethylphenol isomers, have potencies that affect the immune system, being immunogens themselves or modulators of the Th1/Th2 cytokine balance.

Animals↗
PubMed2006

Allergenicity and cross-reactivity of naphthenic acid and its metallic salts in experimental animals.

The allergenicity and the cross-reactivity of naphthenic acid (NA) and its metallic salts were evaluated in experimental animals. In the guinea pig maximization test, sensitizing skin reactions were observed with cobalt naphthenate (CoN), zinc naphthenate (ZnN) and NA, but not with copper naphthenate, with CoN being the most potent sensitizer. Animals sensitized with 1 naphthenic compound cross-reacted to the other 3 as well. Furthermore, animals in the CoN-sensitized group reacted to the relevant metallic salt cobalt chloride (CoCl2). A dose-response study using the CoN-sensitized group showed that the concentration of CoCl2 required to elicit a skin reaction of similar extent in comparison with CoN was more than 10 times higher, when skin-reaction scores were compared on the basis of cobalt content. In the local lymph node assay, significant increases in stimulation index values without skin irritation were observed with CoN and ZnN, where the former was more potent than the latter. Although CoN is a reported skin sensitizer, this study showed that skin allergenicity of naphthenic compounds is not restricted solely to CoN. In addition, the results suggest the main antigenic determinant of naphthenic compounds to be the structure of NA, even though metal moieties modulate their allergenicity.

Allergens↗
PubMed2005

Quantitative comparison of the results obtained by the multiple-dose guinea pig maximization test and the non-radioactive murine local lymph-node assay for various biocides.

We compared the results of the multiple-dose guinea pig maximization test (GPMT) and the non-radioactive murine local lymph-node assay (LLNA) for various biocides. Thirteen out of 17 positive biocides in the GPMT gave positive results in the LLNA. In the GPMT, the minimum first induction doses ranged over four orders (0.00005-0.5%), while elicitation-threshold doses, which were evaluated using an optimally sensitized group of animals in the multiple-dose studies, ranged over five orders (0.00006-2.8%). In the LLNA, minimum induction doses ranged over more than three orders (0.01-30%). With respect to 13 biocides that were positive in both the GPMT and the LLNA, results were quantitatively compared. When compared after conversion to corresponding area doses (microg/cm), the minimum doses required to elicit skin reaction in guinea pigs were always lower than that for induction in mice with all biocides. Correlation between minimum induction doses from the GPMT and the LLNA seemed poor (r=0.57), while that between minimum induction doses in the LLNA and elicitation-threshold doses in the GPMT was relatively good (r=0.73). The results suggest the possibility to estimate human elicitation-threshold doses, which are definitely lacking in the process of risk assessment for skin-sensitizers, from the data of the LLNA.

Administration, Topical↗
PubMed2004

The unconscious cost of good fortune: implicit and explicit self-esteem, positive life events, and health.

J. D. Brown and K. L. McGill (1989) found that positive life events were associated with better health only for people high in self-esteem. Among people low in self-esteem, positive life events were associated with poorer health. The authors of this study replicated this finding in a self-report survey of 61 male and 110 female college students. In addition, they showed that implicit self-esteem moderated the relation between positive life events and self-reported health in the same fashion as explicit self-esteem did. Whereas people high in implicit self-esteem reported being healthier when they experienced more positive life events, people low in implicit self-esteem reported being healthier when they experienced fewer positive life events. Moreover, the effects of implicit self-esteem were statistically independent of the effects of explicit self-esteem.

Adult↗
PubMed2004

Allergenicity evaluation of Bioban CS-1135 in experimental animals.

An industrial preservative, Bioban CS-1135, was evaluated for its contact allergenicity by means of multiple-dose guinea-pig maximization test and non-radioactive murine local lymph node assay. In the guinea-pig test, an induction dose of 0.5% Bioban CS-1135 sensitized all animals of the group. The dose-response study of the elicitation phase determined a minimum elicitation dose of 5% for positive skin reactions. In the murine assay, Bioban CS-1135 at doses of 10% and more exerted significant effects on lymphoid cell proliferation. Although the data clearly designated Bioban CS-1135 as a skin sensitizer, its relative potency was ranked lowest among skin-sensitizing biocides previously evaluated in this laboratory.

Allergens↗
PubMed2004

[Evaluation and estimation of entrance skin dose in patients during diagnostic and interventional radiology procedures].

A study was performed to evaluate the total entrance skin dose (ESD) of patients during diagnostic and interventional radiology procedures (IVR) and to estimate ESD with body mass index (BMI) and fluoroscopy time. The study included 26 cases of transcatheter arterial embolization therapy (TAE) for hepatocellular carcinoma (HCC) and 19 cases of diagnostic digital subtraction angiography (DSA) for HCC. The ESD of patients was evaluated with a zinc-cadmium sensor linked to a digital counter (SDM: skin dose monitor). Exposure doses were measured with SDM attached to the front of the X-ray beam-limiting device like a dose area product monitor. ESD was calculated from the measured exposure dose. In 26 TAE for HCC, ESD was 1793.7+/-739.1 mGy, with the mean fluoroscopic time of 23.5 minutes and 4.4 DSA acquisitions. The fluoroscopic dose rate was 52.4+/-11.5 mGy/min. In 19 diagnostic DSA for HCC, ESD was 962.9+/-375.2 mGy, with the mean fluoroscopic time of 11.1 minutes and 4.0 DSA acquisitions. The fluoroscopic dose rate was 32.7+/-12.7 mGy/min. Although 33.2% of ESD was from fluoroscopy in diagnostic procedures, the figure was 68.8% in TAE procedures. It was demonstrated that the increase in ESD during IVR was caused by the rise of fluoroscopy dose rate caused by high-magnification fluoroscopy and the extension of fluoroscopy time. In order to reduce ESD, it is necessary to use a low fluoroscopy dose rate with low-rate pulse fluoroscopy, in addition to shortening fluoroscopy time. Fluoroscopy time was a poor predictor of risk because it did not correlate well with ESD during IVR (diagnostic procedures r(2)= 0.897, IVR r(2)= 0.594). However, ESD correlated well with the product of BMI and fluoroscopy time (diagnostic procedures r(2)= 0.910, IVR r(2)= 0.783). The linear relationship between ESD and the product of BMI and fluoroscopy time provides a simple monitoring mechanism of the ESD delivered to the patient during interventional radiology procedures. This linear relationship needs to be established for other types of interventional procedures.

Angiography, Digital Subtraction↗
PubMed2003

Allergenicity evaluation of p-chloro-m-cresol and p-chloro-m-xylenol by non-radioactive murine local lymph-node assay and multiple-dose guinea pig maximization test.

p-Chloro-m-cresol (PCMC) and p-chloro-m-xylenol (PCMX) are known to cause allergic contact dermatitis. For risk assessment of skin sensitizers, information on dose-response profiles in the induction and elicitation phases and cross-reactivity with analogous chemicals are important. In the non-radioactive local lymph-node assay (LLNA) using 5-bromo-2'-deoxyuridine instead of 3H-methyl thymidine, significant effect on lymph node cell proliferation was detected at 10% PCMC and 25% PCMX, while in the multiple-dose guinea pig maximization test (GPMT) at least one animal tested in the group was sensitized at a 5 ppm induction dose of either chemical. When mean skin reaction score in an animal group maximally sensitized with each allergen with the GPMT was plotted against log challenge concentration, linear regression lines with high correlations were obtained in both cases. The calculated elicitation threshold was lower for PCMC than PCMX. The area under the linear regression line between the threshold point and 1% of the elicitation concentration, another index of relative elicitation potency, was also greater for PCMC. Bidirectional cross-reactivity between PCMX and PCMC was detected in the GPMT. PCMC was thus identified in both LLNA and GPMT as a stronger sensitizer than PCMX in both the induction and elicitation phases. These results suggest that the non-radioactive LLNA is a simple and useful method for evaluating allergenicity in the induction phase, while the GPMT using a maximally sensitized animal group is more suitable for assessing the dose-response profile and cross-reactivity in the elicitation phase.

Allergens↗
PubMed2002

Simultaneous determination of metabolites of trimethylbenzenes, dimethylbenzylmercapturicacid and dimethylhippuric acid, in human urine by solid-phase extraction followed by liquid chromatography tandem mass spectrometry.

We describe a novel method for the determination of three kinds of dimethylbenzylmercapturic acids (DMM) and six kinds of dimethylhippuric acids (DMH), found in urine as metabolites of trimethylbenzenes, based on liquid chromatography/electrospray ionization tandem mass spectrometry. A solid-phase extraction procedure was used for the extractions of DMM and DMH from a urine sample, and the separation was performed on a reversed-phase C(30) column. The analytes were ionized by electrospray in the positive-ion mode. Operating in the multiple reaction monitoring mode, the linearity of the relative mass spectrometric responses to the internal standard versus analyte concentrations were established in the range 0.1-100 ng ml(-1). The extraction procedure was rapid and the relative standard deviations were below 5%. The detection limits of DMM and DMH in the urine by the proposed method were in the ranges 0.26-0.41 and 0.42-2.0 ng l(-1), respectively. Furthermore, DMM and DMH were detected in a urine sample from an individual who did not suffer from occupational exposure to trimethylbenzenes, by using this method.

Acetylcysteine↗
PubMed2002

[The radiation protective devices for interventional procedures using computed tomography].

A scattered dose and a surface dose from phantom measurements during interventional procedures with computed tomography (IVR-CT) were evaluated. To reduce the personnel exposure in IVR-CT, the new protective devices were developed and its effect evaluated. Two radiation protection devices were experimentally made using a lead vinyl sheet with lead equivalent 0.125mmPb. The first device is a lead curtain which shields the space of CT-gantry and phantom for the CT examination. The second device is a lead drape which shields on the phantom surface adjacent to the scanning plane for the CT-fluoroscopy. Scattered dose and phantom surface dose were measured with an abdominal phantom during Cine-CT (130 kV, 150 mA, 5 seconds, 10 mm section thickness). They were measured by using ionization chamber dosimeter. They were measured with and without a lead curtain and a lead drape. Scattered dose rate was measured at distance of 50-150 cm from the scanning plane. And, surface dose was measured at distance of 4-21 cm from the scanning plane on the phantom. On operator's standing position, scattered dose rates were from 8.4 to 11.6 micro Gy/sec at CT examination. The lead curtain and the lead drape reduced scattered dose rate at distance of 50 cm from the scanning plane by 66% and 58.3% respectively. Surface dose rate were 118 micro Gy/sec at distance of 5 cm from the scanning plane at CT-fluoroscopy. The lead drape reduced the surface dose by 60.5%. High scattered exposure to personnel may occur during interventional procedures using CT. They were considerably reduced during CT-arteriography by attaching the lead curtain in CT equipment. And they were substantially reduced during CT-fluoroscopy by placing the lead drape adjacent to the scanning plane, in addition, operator's hand would be protected from unnecessary radiation scattered by phantom. It was suggested that the scattered exposure to personnel could be sufficiently reduced by using radiation protection devices in IVR-CT. The radiation protection devices and the CT equipment should be improved or developed based on the radiation protection.

Humans↗