Mikio Nishida

Simultaneous analysis of dehydroacetic acid, benzoic acid, sorbic acid and salicylic acid in cosmetic products by solid-phase extraction and high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) method for simultaneous determination of dehydroacetic acid (DHA), benzoic acid (BA), sorbic acid (SOA) and salicylic acid (SA) was developed for application to cosmetic products. Isocratic reversed-phase HPLC was employed for quantitative analysis using tetra-n-butylammonium (TBA) hydroxide as an ion-pair reagent. Cosmetic samples were purified by solid-phase extraction using Bond-Elut SI cartridges. Four acidic preservatives were eluted with methanol from cartridges. The HPLC assay was carried out using TSK gel ODS-80TM column (5 microm, 150 x 4.6 mm I.D.). The mobile phase consisted of a mixture of water and methanol (65:35, v/v) containing 2.5 mM TBA hydroxide adjusted with phosphoric acid to pH 7.0. The calibration curves of these preservatives showed good linearity with UV detection (235 nm). The correlation coefficients were better than 0.999 in all cases. The lower limits of detection (defined as a signal-to-noise ratio of about 3) were approximately 2.5 ng for DHA, 4.0 ng for BA, 2.0 ng for SOA and 5.5 ng for SA. The procedure described here is simple, selective and is suitable for quality control of finished cosmetic products.

Enhancement by streptozotocin of O−2 radical generation by the xanthine oxidase system of pancreatic β-cells

Spin‐trapping techniques and electron spin resonance (ESR) spectroscopy were used to study the relationship between the effect of streptozotocin (STZ) on pancreatic β‐cells and free radical formation by these cells. Results showed that STZ enhanced generation of the DMPO‐OH radical adduct, which is a degradation product of the superoxide anion (O− 2) in the presence of cellular components, in a hypoxanthine‐xanthine oxidase (XOD) system with a homogenate of β‐cells. This enhancing effect was also observed in a system without cellular components; STZ increased the signal height due to the O− 2 radical in a concentration‐dependent manner and caused a maximum of 150% enhancement at a concentration of 1.5 mM. Thus, STZ seemed to enhance the generation of the O− 2 radical in the XOD system, probably by some mechanism of its interaction with XOD. Pancreatic β‐cells exhibited a high XOD activity and a very low superoxide dismutase activity. Therefore, the present result supports the possibility that the cytotoxic effect of STZ is closely related to free radical generation in pancreatic β‐cells.

Neurosteroids Ameliorate Conditioned Fear Stress: An Association with Sigma1 Receptors

Mice exhibited a marked suppression of motility (conditioned fear stress) when placed in an environment in which they had previously received an electric footshock. This conditioned fear stress response was dose-dependently attenuated by neurosteroids such as dehydroepiandrosterone sulfate (DHEAS; 25 and 50 mg/kg, s.c.) and pregnenolone sulfate (PREGS; 10–50 mg/kg, s.c.), and by a putative sigma1 receptor agonist, (+)-N-allylnormetazocine ((+)-SKF-10,047; 3 and 6 mg/kg, s.c.). However, progesterone (PROG; 10–50 mg/kg, s.c.) and allopregnanolone (5 and 20 mg/kg, s.c.) had no effect on this stress response. The attenuating effects of DHEAS (50 mg/kg, s.c.), PREGS (50 mg/kg, s.c.), and (+)-SKF-10,047 (6 mg/kg, s.c.) were reversed by NE-100 (5 mg/kg, i.p.), a sigma1 receptor antagonist and PROG (5 or 10 mg/kg, i.p.). When DHEAS (25 mg/kg) was co-administered with (+)-SKF-10,047 (3 mg/kg) at doses that do not affect the conditioned fear stress response by themselves, motor suppression was significantly attenuated. In mice showing the conditioned fear stress response, the serum concentration of DHEAS was lower than that in non-shocked mice. These results suggest that the attenuating effects of DHEAS and PREGS on the conditioned fear stress response are mediated via sigma1 receptors and that PROG has a sigma1 receptor antagonistic property. Further, the endogenous DHEAS may be involved in the expression of conditioned fear stress response in mice.

Partition of divalent and total manganese in organs and subcellular organelles of MnCl2-treated rats studied by ESR and neutron activation analysis

The possibility that Mn2+ is converted to other valency states in vivo was examined by measuring the ratio of Mn2+, determined by ESR, to total manganese, determined by neutron activation analysis combined with chemical separation, in various organs of control rats and rats treated with MnCl2. In control rats, the total manganese content was high in the thyroid, hypophysis, adrenal, pancreas, liver and kidney, but the Mn2+ contents of these organs were low. In rats treated with Mn2+, the total manganese contents of all organs increased, but the Mn2+ contents still remained low. With regard to subcellular distribution, the total manganese content was high in the nuclear and mitochondrial fractions of the liver and kidney, and in the microsomal and supernatant fractions of the pancreas. The ratio of Mn2+ to total manganese was relatively high in the microsomes of the liver and kidney of control rats, and in the nuclear fraction of the pancreas of Mn2+-treated rats. Thus, the distribution and behavior of manganese in the pancreas were different from those in other organs. Purified liver nuclei and mitochondria were demonstrated to contain manganese, indicating that manganese is tightly bound in each cellular compartment.

Development of a dual color enzyme-linked immunospot assay for simultaneous detection of murine T helper type 1- and T helper type 2-cells

The enzyme-linked immunospot (ELISPOT) assay is an efficient technique for the enumeration of single cells secreting antibodies and cytokines. For simultaneous differentiation of individual cells producing interleukin-2 (IL-2) and/or interleukin-4 (IL-4) at a single cell level, a dual color ELISPOT assay has been developed. In the present system, the red spots corresponding to IL-2-secreting cells (T helper type 1, Th1 cells) were developed with a horseradish peroxidase and the amino ethyl carbazole (AEC)/H2O2. The light blue spots corresponding to IL-4-secreting cells (T helper type 2, Th2 cells) were developed with an alkaline phosphatase and the Vector blue. The mixed colored (indigo) spots corresponding to both kinds of cytokine-secreting cells (T helper type 0, Th0 cells) were developed with both substrates. With this system, we could detect the IL-2- and/or IL-4-secreting cells simultaneously in crude spleen cell preparation or purified CD4 fraction. This procedure provides a useful tool for quantitatively analyzing micro-levels of dynamic immune responses.

A wide interindividual variability of urinary 6β-hydroxycortisol to free cortisol in 487 healthy Japanese subjects in near basal condition

The frequency distribution of CYP3A activity was investigated by measuring ratios of urinary 6&bgr;-hydroxycortisol to free cortisol in 487 healthy subjects to determine whether a genetic polymorphism for this cytochrome enzyme exists in “native-born” Japanese persons. Spot urine samples (from 9:00 am to 12:00 pm) were collected for measurement of 6&bgr;-hydroxycortisol and free cortisol by high-performance liquid chromatography with a CN column after extracting with a solid-phase column (Bond-Elut C18). The frequency distribution of the urinary 6&bgr;-hydroxycortisol to free cortisol was widely distributed among subjects but with no clear bimodality by a probit plot. Furthermore, the frequency distribution assessed on a new normal test variable plot indicated the possible existence of a CYP3A sexual dimorphism. Mean 6&bgr;-hydroxycortisol levels were higher in women (n = 249) than in men (n = 238) by 1.7-fold, and this difference was statistically significant (P < 0.01). These results show that a CYP3A genetic polymorphism in Japanese persons, based on 6&bgr;-hydroxycortisol excretions, likely does not exist, but there appears to be a broad unimodal distribution of enzyme activity in the population.

Characterization of the cytokine network at a single cell level in mice with collagen-induced arthritis using a dual color ELISPOT assay.

Collagen-induced arthritis (CIA) in mice has been classified as a Thl-mediated disease. However, most evidence for this has been obtained by indirect experiments; for example, the administration of neutralizing anti-interferon-gamma (IFN-gamma) antibody reduced the severity of arthritis. To obtain direct evidence about the cytokine balance in CIA mice, we analyzed the cytokine-secreting cell in CIA mice at the single cell level using a dual color enzyme-linked immunospot (ELISPOT) assay, which enabled us to analyze interleukin-2 (IL-2)-secreting cells or IL-4-secreting cells or both simultaneously. Furthermore, to characterize the cytokine network in the pathogenesis of CIA, the frequency of the cells secreting IL-12, which induced the development of naive Th cells into Th1 cells, was analyzed. The results show that in the prearthritic phase, the number of IL-12-secreting cells in spleen and peritoneal exuded cells is increased, and Th1 cells in lymph node and spleen are dominant. In contrast, after the onset of clinical arthritis, the number of IL-12-secreting cells in spleen, lymph node, and peritoneal exuded cells is decreased, and there is a shift from a Thl-dominant to a Th2-dominant state in lymph node and spleen. The results indicated that the pathogenesis of CIA is associated with a disruption in the normal ratio of Th1/Th2 at cell level.

New Diabetogenic Streptozocin Analogue, 3-O-Methyl-2-{[(methylnitrosoamino) carbonyl]amino}-D-glucopyranose: Evidence for a Glucose Recognition Site on Pancreatic B-Cells

The nonmetabolizable glucose analogue 3-O-methylglucose is known to protect pancreatic B-cells against streptozocin (STZ) when injected with or just before STZ. If 3-O-methyl-glucose and the sugar moiety of STZ compete for a glucose recognition site on B-cells, it seemed likely that 3-O-methyl-2-deoxy-2-{[(methylnitrosoamino) carbonyl]amino}-D-glucopyranose, an analogue of STZ with a 3-O-methyl-glucosyl residue, would cause experimental diabetes. This possibility was tested by synthesis of this analogue (α-anomer) and comparison of its diabetogenic activity in Wistar rats with that of STZ. Results showed that the compound was diabetogenic and as potent as STZ. This new analogue is the first of the various STZ derivatives reported to show diabetogenic activity. Its activity supports the idea that 3-O-methyl-glucose and STZ bind competitively with a glucose recognition site on pancreatic B-cells.

Age-dependent decrease in serum transforming growth factor (TGF)-beta 1 in healthy Japanese individuals; population study of serum TGF-beta 1 level in Japanese

Transforming growth factor-beta1 (TGF-β1), a multi-functional cytokine, is involved in regulating a variety of cellular activities and the serum/plasma TGF-β1 level is altered with various diseases. However, most published reports have described adult patients, and so we investigated the clinical significance of serum TGF-β1 level in pediatric patients. The diagnostic application of the measurement of serum TGF-β1 level depends critically on the control value, however, there is no information on the control value of serum TGF-β1 for children. In the present study, we determined the serum TGF-β1 level of healthy Japanese children as a control value with enzyme-linked immunosorbent assay (ELISA). The serum TGF-β1 level of children (0–14 years old) was significantly higher than that of adults (over 15 years old) (p < 0.01). Thus, it is recommended that when the serum TGF-β1 levels of patients are evaluated, they should be compared with those of age-matched controls.

Effect of Dietary Fiber on Morphine-induced Constipation in Rats

Morphine is used to alleviate chronic cancer pain. However, constipation is a major adverse effect that often detracts from the patients quality of life. In this study, we investigated the effectiveness of dietary fiber on morphine-induced constipation. Rats were fed on a normal diet or one containing either 10% or 20% apple fiber for two weeks before morphine was administered. In the control diet group, the fecal number and dry weight were decreased by treating with morphine in a dose-dependent manner. Moreover, the motility of the small and large intestines was reduced. The fecal number and weight were increased and the colon motility was promoted by dietary fiber, regardless of whether morphine was being administered. The dietary fiber increased the concentration of short-chain fatty acids (SCFAs) in the cecum. These results suggest that dietary fiber has a preventative effect on morphine-induced constipation by increasing SCFAs in the cecum, and thereby promoting colon motility in rats.