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Biomedical subjects

Ayako Suzuki

Publications and source records attributed to Ayako Suzuki.

At least 19 recordsLinked to original sources
PubMed2006

Clinical predictors for hepatocellular carcinoma in patients with primary biliary cirrhosis.

BACKGROUND & AIMS: Although hepatocellular carcinoma (HCC) occurs with increased frequency in patients with primary biliary cirrhosis (PBC), the exact frequency is relatively low. Optimal selection of PBC patients for HCC screening needs to be determined for effective screening. In this study, we aimed to explore clinical predictors of HCC in PBC patients. METHODS: We performed a case-control study using 17 PBC patients with HCC identified from 1976 to 2002 at the Mayo Clinic. Control PBC patients who had no evidence of HCC were selected for each case by matching the first year of their visit to the Mayo Clinic. All medical information was collected within 2 years from when the cases were diagnosed with HCC. Logistic regression models were used for the analyses. RESULTS: Age, sex, history of blood transfusion, current smoking, histologic stage at PBC diagnosis, any signs of portal hypertension, Mayo score, hemoglobin level, platelet count, aspartate aminotransferase level, and albumin level were associated with the presence of HCC (P < .05 for each). In multivariable analysis, older age (OR, 1.7; 95% confidence interval [CI], 1.1-2.5 for 5 years), male sex (OR, 9.7; 95% CI, 1.4-68.3), history of blood transfusion (OR, 5.0; 95% CI, 1.0-24.3), and any signs of portal hypertension (OR, 22.9; 95% CI, 3.4-155.3) were associated significantly with increased odds of HCC and yielded an excellent diagnostic performance (area under the receiver operating characteristics curve rate, 0.91). CONCLUSIONS: Older age, male sex, history of blood transfusion, and any signs of portal hypertension or cirrhosis indicate higher likelihood of HCC and should be considered for HCC screening. Further studies in larger patient cohorts are required to verify the diagnostic model.

Adult↗
PubMed2006

Serum insulin levels and the prevalence of adenomatous and hyperplastic polyps in the proximal colon.

BACKGROUND & AIMS: Obesity and diabetes mellitus are associated with an increased incidence of proximal colon cancer. Colonic adenoma that has been reported to be associated with elevated serum insulin levels and subsets of hyperplastic polyps might serve as a precursor of colon cancer. In this study, we sought to determine segment-specific associations between serum insulin levels and the prevalence of adenoma and hyperplastic polyps in the proximal and distal colon. METHODS: We studied 343 consecutive patients who underwent colonoscopy in our hospital. All medical information, including fasting serum insulin, was obtained at colonoscopy. We performed multinomial logistic regression models by using the outcome categories of none (reference), proximal-only, distal-only, and both-segment lesions for the presence of adenoma/hyperplastic polyp with serum insulin, age, gender, lifestyle characteristics, and the presence of other types of lesions as predictors. Odds ratios (ORs) and 95% confidence intervals (CIs) are provided for a 5-muU/mL increase in serum insulin. RESULTS: Overall, serum insulin levels were significantly associated with adenoma (OR, 1.5; 95% CI, 1.1-2.0; P = .005) and borderline associated with hyperplastic polyps (OR, 1.3; 95% CI, 1.0-1.7; P = .075). In multinomial logistic regression models, elevated serum insulin levels were significantly associated with proximal-only adenoma (OR, 1.8; 95% CI, 1.2-2.5; P = .002), both-side hyperplastic polyp (OR, 1.7; 95% CI, 1.1-2.5; P = .015), and proximal-only hyperplastic polyp (OR, 1.5; 95% CI, 1.0-2.1; P = .048) and borderline associated with distal-only adenoma (OR, 1.5; 95% CI, 1.0-2.1; P =.059) but not with distal-only hyperplastic polyp. CONCLUSIONS: Serum insulin levels directly correlate with the presence of adenoma and hyperplastic polyps in the proximal colon and might also less strongly correlate with the presence of distal adenoma.

Adenomatous Polyposis Coli↗
PubMed2006

Interleukin-15 increases hepatic regenerative activity.

BACKGROUND/AIMS: Interleukin-15 (IL-15) is expressed in many organs. It generally inhibits apoptosis and increases cellular proliferation and differentiation. However, IL-15's roles in liver are unknown. We aimed to determine if IL-15 influences hepatic integrity and regenerative activity. METHODS: Expression of IL-15 and its receptors was evaluated in several liver injury models, primary hepatocytes, and two liver cell lines. Effects of IL-15 on viability, proliferation, and apoptosis were assessed in cultured liver cells, and also in the livers of healthy mice. RESULTS: IL-15 and its receptors are expressed constitutively in healthy livers, and ligand expression is induced in injured livers. Cultured primary hepatocytes and liver cell lines express IL-15 and its receptors. Administration of IL-15 has minimal effects on cultured liver cells, but significantly up-regulates oval cell accumulation, cyclin mRNA expression, and mature hepatocyte replication in healthy mice. These effects are associated with focal hepatic inflammation and increased expression of TNF-alpha and IFN-gamma, but not with increased cell death or aminotransferase release. CONCLUSIONS: IL-15 expression increases during liver injury and IL-15 treatment induces a wound healing-type response in healthy adult mice. These findings suggest that IL-15 may contribute to regenerative activity in damaged liver.

Animals↗
PubMed2006

Inhibition of fatty acid beta-oxidation attenuates the reinforcing effects and palatability to fat.

OBJECTIVE: We investigated the effects of the energy signal on the reinforcing effects and palatability to fat in mice. METHODS: To examine the effects of postingestive energy signal, mice were injected with 400 micromol/kg body mass of mercaptoacetate, a beta-oxidation blocker or with saline (control group). Reinforcing effects and palatability response were examined with the conditioned place preference and one-bottle tests, respectively. RESULTS: In conditioned place preference tests, the mercaptoacetate group exhibited reinforcing effects when offered a 40% sucrose solution, which is not metabolized by the beta-oxidation pathway, but not when offered 100% corn oil. The control group exhibited reinforcing effects when offered the sucrose solution and when offered corn oil. In one-bottle tests, the control group exhibited palatability to corn oil, but the mercaptoacetate group did not. Consumption of sucrose solution was identical for both groups. CONCLUSIONS: These results suggest that postingestive energy signal influences the reinforcing effects and palatability of fat.

Animals↗
PubMed2006

Values and limitations of serum aminotransferases in clinical trials of nonalcoholic steatohepatitis.

BACKGROUND/AIMS: Choosing endpoints in nonalcoholic steatohepatitis (NASH) trials is challenging because of the lack of validated surrogates and the trade-off between accuracy and invasiveness. In this study, we assessed diagnostic accuracy of serum aminotransferase changes in predicting histological changes in NASH trials. METHODS: We conducted a longitudinal cohort study by using 102 participants in ursodeoxycholic acid-NASH trial who had both baseline and 2-year liver biopsy and multiple measurements of serum aminotransferases. We calculated rates of alanine aminotransferase (ALT) [or aspartate aminotransferase (AST)] change as slopes of linear regression over 2 years (IU/l/month) and changes in each histological feature as differences in Brunt's scores of two biopsies in each individual. RESULTS: Rate of aminotransferase change correlated with changes in inflammation and fibrosis, but not steatosis and only with change in inflammation in multivariable analysis. In each histological feature, changes were inversely correlated with baseline histological grade. In predicting improvement of inflammation, areas under the receiver-operating characteristic curve of aminotransferase information alone were 0.72 for ALT and 0.73 for AST and were improved to 0.88 and 0.89, respectively, when baseline histology were taking account of. CONCLUSIONS: Serum aminotransferase changes could be useful as surrogates in screening therapies for NASH in clinical trials with appropriate consideration of baseline aminotransferase and histology.

Adult↗
PubMed2006

Effects of minocycline and doxycycline on cell survival and gene expression in human gingival and periodontal ligament cells.

OBJECTIVES AND BACKGROUND: Periodontitis is an infectious disease in the gingival crevice caused by periodontopathic bacteria, including Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, and Tennerella forsythensis, and antibacterial agents are directly administered to the site of infection to treat it. To maximize the therapeutic effects while reducing the adverse effects, the antibacterial agents should be administered at concentrations greater than their MIC(90) doses required to inhibit the growth of 90% of periodontopathic bacteria and the administration should not damage the periodontal tissue. One approach for estimating cellular damage in the periodontal tissue caused by the administration is to assay cytological damages following exposures of cultured human cells derived from periodontal tissues to antibacterial agents. In the present study, we investigated the cytotoxic effect of minocycline (MINO) and doxycycline (DOX) by using a human gingival fibroblast cell line, a human gingival epithelial cell line, and a human periodontal ligament fibroblast cell line. We also used these cell lines to study the effect of MINO or DOX on the mRNA and protein expressions of genes associated with the differentiation of fibroblasts and the proliferation, differentiation, or cellular adhesion important to the epithelial regeneration of the periodontal attachment. METHODS: The cytotoxic effect of MINO or DOX was measured as a decrease in cell survivals. The effects of these antibiotics on the mRNA and protein expressions in the cell lines were studied by reverse transcription-polymerase chain reaction (RT-PCR) and western blot analyses, respectively. RESULTS: The maximum concentration of MINO or DOX that has little effect on the cell survivals and the mRNA and protein expressions of genes for alkaline phosphatase, type I procollagen, keratinocyte growth factor receptor, keratin 18 or 8/18, integrin beta1, integrin beta4, and laminin 5gamma2 was 10 or 30 microm, respectively, which are greater than their MIC(90) doses against periodontopathic bacteria described above. CONCLUSIONS: These findings suggest that little, if any, cellular damage would be expected with topical administration of MINO or DOX to the periodontal pocket at a dose equivalent to the MIC(90). It is important to note, however, that the extrapolation of these findings to in vivo conditions has yet to be undertaken.

Administration, Topical↗
PubMed2006

Proteomic analysis of a highly metastatic gastric cancer cell line using two-dimensional differential gel electrophoresis.

Stomach cancer is still a major cause of death in Asian people despite a complete cure after the resection of early cancers, mainly because peritoneal dissemination is difficult to treat. In the present study, we used two-dimensional differential gel electrophoresis (2-D DIGE) to identify specific proteins differentially expressed between a highly metastatic stomach cancer cell line MKN-45-P and its parental cell line MKN-45. We detected 27 protein spots in at least 2 of 3 experiments which showed statistically significant differences in abundance. All 27 protein spots were identified using matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry (MS) and database-searching software. A proteomic analysis revealed 13 different proteins with some isoforms sharing different biochemical characteristics, and that 8 proteins were up-regulated, and 5 were down-regulated. The 13 proteins were mainly involved in protein synthesis (transfer RNA synthetase), metabolism (flavoprotein subunit, pyruvate kinase, adenylate kinase), receptor and signal transduction (annexins I and A2), the cytoskeleton (keratin 5, cytokeratin 8) and cell cycling (ts11). These results suggested that a proteomic approach including 2-D DIGE would be an efficient way to identify the proteins responsible for specific biological functions. Moreover, these observations might be novel findings leading to the prediction of postoperative peritoneal recurrence.

Cell Line, Tumor↗
PubMed2005

Electron paramagnetic resonance decay constant and oxidative stresses in liver microsomes of the selenium-deficient rat.

The free radical-reducing activity and the membrane fluidity of liver microsomes from selenium-deficient (SeD) rats were examined by means of electron paramagnetic resonance (EPR) spin label method using nitroxyl-labeled stearic acids. Our findings show that the membrane fluidity and lipid peroxidation levels in SeD rat liver microsome were relatively unchanged compared with normal rat. In contrast, SeD caused the induction of liver microsomal cytochrome P-450 activity. The nitroxyl spin probes are substrates for reduction-relating cytochrome P-450. Previous in vivo studies suggested that the total liver free radical reduction activity in SeD rat was decreased. In contrast, SeD caused the induction of liver microsomal cytochrome P-450 activity, and the reduction rate of nitroxyl radical existing at shallow depth in membrane was increased. Selenium-deficient rats experienced an increase in hydrogen peroxide (H2O2) due to a pronounced loss of glutathione peroxidase (GSH-Px) activity. This masked the overall reduction rate of the nitroxyl spin probe by reoxidation of the hydroxylamine form. Although the SeD condition caused induction of liver cytochrome P-450 and chronic increased H2O2, this did not result in oxidative liver damage. An increased level of glutathione in SeD liver was also evident, likely due to the absence of GSH-Px activity. Using the EPR spin label method, we have shown that SeD causes complicated redox changes in the liver, notably, alterations in the levels of cytochrome P-450 and GSH-Px systems.

Animals↗
PubMed2005

Effect of changes on body weight and lifestyle in nonalcoholic fatty liver disease.

BACKGROUND/AIMS: The effects of lifestyle modifications in nonalcoholic fatty liver disease (NAFLD) are incompletely defined. We aimed at determining the association of changes in body weight and lifestyle with changes in serum ALT levels. METHODS: We analyzed annual health checkup data from 1546 employees. Of 469 subjects with elevated ALT, we selected 348 male subjects by excluding those who had other causes of liver disease. They were followed for one year to assess the association of change in lifestyle with change in serum ALT. The 136 subjects who had ALT normalization were followed for two years to assess the association between lifestyle management and persistently normal ALT. RESULTS: In adjusted analysis, weight loss and regular exercise were significantly associated with improvement in serum ALT and increased the odds of ALT normalization, while starting smoking was significantly associated with deterioration in serum ALT. Subjects achieving > or = 5% weight reduction showed improvement in serum ALT. Reduction in alcohol consumption was not associated with changes in serum ALT. Maintaining reduced weight (<5% gain) was significantly associated with persistently normal ALT. CONCLUSIONS: Reducing weight by at least 5% with subsequent weight control and exercising regularly may be beneficial in treating NAFLD.

Adult↗
PubMed2005

Chronological development of elevated aminotransferases in a nonalcoholic population.

The incidence and risk factors of nonalcoholic fatty liver disease (NAFLD) have never been prospectively determined. To determine the frequency and risk factors of NAFLD and chronological ordering between NAFLD, weight gain, and features of insulin resistance, a historical cohort study was conducted in a Japanese workplace. A cohort free of previous liver injury, alcohol consumption of more than 140 g/wk, and hepatitis B or C infection (529 of 1537 subjects), and a subcohort of 287 subjects free of insulin resistance-related features were identified. Elevated aminotransferases in nonalcoholics were used as a surrogate for NAFLD. High aminotransferases together with weight gain of more than 2 kg and insulin resistance-related features in the subcohort were sought for up to 5 years. The incidence of high aminotransferases was 31 per 1000 person-years (71 events). A significant interaction occurred between age and sex in the development of high aminotransferases. In subjects younger than age 40 years, male sex (hazard ratio [HR]: 4.6), elevated body mass index (HR: 2.1), hypertension (HR: 2.6), and low high-density lipoprotein cholesterol (HR: 2.8) increased the risk of high aminotransferases, whereas age (HR: 0.6 for each 5 years) decreased the risk. In subjects older than age 40 years, glucose intolerance (HR: 5.3) was the only significant risk factor. In the subcohort, weight gain preceded high aminotransferases and other insulin resistance-related features, which appeared sequentially in order of low high-density lipoprotein cholesterol, hypertriglyceridemia/hypertransaminasemia/hypertension, and glucose intolerance. In conclusion, this cohort study clearly showed chronological ordering and an association between development of elevated aminotransferases and risk factors of NAFLD.

Adult↗
PubMed2005

Diagnostic model of esophageal varices in alcoholic liver disease.

Esophageal varices may cause life-threatening bleeding with attendant high hospital cost. Since effective preventive modalities for variceal hemorrhage have been established, early detection of esophageal varices is critical for prevention of bleeding. Currently, endoscopic screening is widely recommended to patients who have the diagnosis of cirrhosis. However, the diagnosis of cirrhosis relies on histological evaluations, which is costly and invasive, and endoscopic screening also burdens medical resources. Recent cost-effectiveness studies suggested that empiric prophylaxis with beta-blockers may be viable in comparison with endoscopic screening in patients with cirrhosis. However, this issue need to be also evaluated taking account of societal and patient perspectives and is not yet decided. An accurate non-invasive diagnostic model to predict the presence of esophageal varices may reduce unnecessary endoscopic procedures and prophylactic medication and improve cost-benefit of these approaches. Use of an accurate serum marker for severe hepatic fibrosis may also improve accuracy of non-invasive diagnostic models. Hyaluronic acid, a serum marker for severe hepatic fibrosis, has been reported to have a high diagnostic performance in assessing the severity of hepatic fibrosis in patients with alcoholic liver disease. In this issue, a non-invasive diagnostic model including hyaluronic acid was shown to have excellent performance in excluding the presence of medium to large esophageal varices in severe alcohol abusers. Based on current evidence, the strategy of using a non-invasive diagnostic model together with a serum marker for severe hepatic fibrosis may improve cost-benefit in the prevention of variceal hemorrhage among patients with alcoholic liver disease. The independent verification of such diagnostic models is needed.

Biomarkers↗
PubMed2005

Dopamine D2-like receptor agonists accelerate barrier repair and inhibit the epidermal hyperplasia induced by barrier disruption.

Two families of G protein-coupled receptors of the neurotransmitter dopamine, i.e., dopamine 1-like family (D1-like receptor) and dopamine 2-like family (D2-like receptor), show dopaminergic activity in nerve cells. The D2-like receptor family, composed of D2, D3, and D4 receptors, downregulates the intracellular cAMP signaling pathway, and dopamine receptor agonists reduce the cAMP level in neurons. We previously demonstrated that the cAMP level in epidermal keratinocytes is related to epidermal barrier homeostasis. Since keratinocytes are known to carry various neurotransmitter receptors, we hypothesized that D2-like receptors on keratinocytes might be related to skin barrier homeostasis. In this study, we examined the effect of topical application of receptor agonists and antagonists on skin barrier recovery after barrier disruption. Application of D2-like receptor agonists accelerated barrier recovery, whereas D2-like receptor antagonists delayed it. D2-like receptor agonists also reduced the epidermal hyperplasia induced by barrier disruption under low environmental humidity. Immunohistochemical study and RT-PCR analysis revealed the expression of the D2 receptor in the basal epidermis and the D4 receptor in the uppermost layer of the epidermis. These results suggest that dopaminergic receptors are involved in epidermal barrier homeostasis.

Animals↗
PubMed2005

Hyaluronic acid, an accurate serum marker for severe hepatic fibrosis in patients with non-alcoholic fatty liver disease.

AIM: To determine whether serum hyaluronic acid reliably predicts the severity of hepatic fibrosis in patients with non-alcoholic fatty liver disease (NAFLD). METHODS: We studied 79 patients with histologically confirmed NAFLD. Hyaluronic acid was measured in serum obtained at the time of liver biopsy. Severity of fibrosis was staged based on Brunt's classification. The prediction levels for fibrosis were determined by area under the receiver operating characteristic curve (AUC). RESULTS: The logarithm of serum hyaluronic acid was significantly different among the stages of fibrosis (P<0.0001, analysis of variance) and had a significant positive correlation with the degrees of fibrosis after adjusting for age and serum albumin (partial r=0.44, P<0.0001). AUCs were 0.67, 0.87, 0.89, and 0.92 for any levels of fibrosis, > or =moderate fibrosis, > or =severe fibrosis, and cirrhosis, all of which were significantly higher than 0.5 (P<0.05). The cut-off value of serum hyaluronic acid of 46.1 mug/l was associated with the highest AUC for severe fibrosis, yielding a sensitivity of 85% and a specificity of 80%. The corresponding positive and negative predictive values were 51% and 96%, when assuming prevalence of severe fibrosis in NAFLD patients of 20% at referral centers. CONCLUSIONS: Measurement of serum hyaluronic acid is useful to identify NAFLD patients with severe fibrosis.

Adult↗
PubMed2005

Risk of colorectal neoplasm in patients with acromegaly and its relationship with serum growth hormone levels.

OBJECTIVES: Acromegalics have been reported to be at an increased risk of colorectal neoplasm. However, the magnitude of the risk is still controversial and the mechanism has not been fully investigated. In this study, we attempted to determine the magnitude of the association between acromegaly and colorectal lesions after taking into account age, gender, smoking status, and treatment status. In addition, we assessed the relationship between colorectal lesions and serum growth hormone (GH) levels in acromegalics. METHODS: We conducted a case-control study by using 19 consecutive untreated patients (male:female = 11:8) who were newly diagnosed with acromegaly between 1990 and 2000. All patients underwent colonoscopy and received a histological diagnosis of colorectal lesions. Prevalence of hyperplastic polyp, adenoma, and carcinoma were compared with the prevalence in 76 controls matched for gender, age, and smoking status. Serum GH levels were compared between acromegalic patients with and without each type of colorectal lesion. RESULTS: The prevalence of hyperplastic polyp, adenoma, and carcinoma were significantly higher in the acromegalic patients compared to the controls (p < 0.05, odds ratios; 8.3, 4.2, and 9.8, respectively). In acromegalics, the presence of hyperplastic polyps and carcinomas were significantly associated with higher serum GH levels after adjusting for the other lesions and age (p < 0.05). CONCLUSIONS: After controlling for age, gender, smoking status, and treatment status, acromegaly was associated with significantly higher prevalence of colorectal hyperplastic polyp, adenoma, and carcinoma. High serum GH levels may be associated with the presence of hyperplastic polyp and carcinoma.

Acromegaly↗
PubMed2005

Spontaneous regression of congenital cystic adenomatoid malformation of the lung: longitudinal examinations by magnetic resonance imaging.

We report a case of large cystic adenomatoid malformation of the lung (CCAM), which occupied almost the entire left lung with a prominent mediastinal shift at 24 weeks of gestation. The volume of the lesion, determined by magnetic resonance imaging (MRI), was 27.0 cm3. Subsequent MRI and ultrasound examinations revealed a spontaneous resolution of the lesion at 32 and 36 weeks of gestation without a mediastinal shift, when the lesion volume was 12.8 cm3 and 5.6 cm3, respectively. At 37 weeks of gestation, a mature male baby weighing 2638 g with an Apgar score of 7 was delivered by elective cesarean section. A lobectomy of the left upper lobe of the lung was carried out at 3 days of age, due to an enlargement of the CCAM after birth.

Adult↗
PubMed2004

In vivo anti-tumor effect of dual release of cisplatin and adriamycin from biodegradable gelatin hydrogel.

The objective of this paper is to investigate the in vivo anti-tumor effect by dual release of cisplatin (CDDP) and adriamycin (ADM) from a biodegradable hydrogel. Hydrogels with different water contents were prepared through the chemical crosslinking of gelatin by various concentrations of glutaraldehyde. Aqueous solution of CDDP, ADM or their mixture (CDDP+ADM) was impregnated into the freeze-dried hydrogel, followed by air-drying to obtain the dried hydrogel incorporating the corresponding drug. Irrespective of the hydrogel water content, 8-20% of CDDP incorporated and 60-80% of ADM was released from the hydrogel in the phosphate-buffered saline solution (PBS) at 37 degrees C within the initial 6 h and thereafter little release was observed. When intratumorally applied into mice carrying a mass of Meth-AR-1 tumor cells, the hydrogel incorporating CDDP+ADM showed significant higher anti-tumor effect on the tumor growth suppression and on survival period than other drug applications. Combination effect assay revealed that the hydrogel incorporating CDDP+ADM showed a synergistic effect between the CDDP and ADM, while the solution form showed antagonistic. The concentration of CDDP and ADM in the tumor tissue maintained at higher levels over 14 days after application. The time course of in vivo CDDP retention was in a good accordance with that of hydrogel remaining, whereas ADM was released faster, followed by the sustained release for 14 days. No practically problematic change in the mouse body and blood biochemical parameters was observed by application of the hydrogel incorporating CDDP+ADM. We conclude that dual sustained release of CDDP and ADM attached to the tumor synergistically enhanced their in vivo anti-tumor effect through the trans-tissue delivery.

Animals↗
PubMed2004

Hair analysis of histamine after fluorescence labeling by column-switching reversed-phase liquid chromatography with electrospray ionization mass spectrometry and application to human hair.

Sensitive determination of histamine (HA) in hair was carried out by column-switching reversed-phase high-performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC-ESI-MS). HA was labeled with excess amounts of 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (DBD-F) at 60 degrees C for 30 min in a mixture of 0.1 M borax (pH 9.3) and acetonitrile (CH(3)CN). The resulting DBD-HA derivative was roughly separated by a Mightysil RP-18 GP (100 x 2mm i.d., 3 microm) with an acidic mobile phase containing 0.1% trifluoroacetic acid. DBD-HA in the fraction flowing due to a position change in the six-port column-switching valve was then completely separated by a Wakopak Navi C30 (150 x 2mm i.d., 5 microm) with 20 mM AcONH(4)-CH(3)CN (8:2). The mass spectrometer was operated in the selected reaction monitoring (SRM) mode for the product ion (m/z 292) obtained from MS-MS measurement using the protonated molecular ion [M+H](+) (m/z 337) as the precursor ion. Good linearity was achieved from the calibration curve obtained by plotting peak area ratios of the internal standard (HA-d(4)) against the injected amounts of HA (1.66-16.6 pmol, r(2)=0.999). The coefficients of variation, at 1.66- and 16.6-pmol injections, were 5.6 and 3.7%, respectively (n=6). Furthermore, the detection limit was 0.167 pmol. The efficiency of the recommended procedure was identified from the determination in the rat hair root after intraperitoneal administration of HA. The proposed method was applied to HA determination in the hair shaft of Dark Agouti rats and healthy volunteers. The variations in the concentrations in 1mg of hair shaft were 0.80-1.84 pmol (mean+/-SD=1.33+/-0.33, n=12) in rats and 0.94-72.3 pmol (17.2+/-21.5, n=16) in humans. The determination of HA in the plasma of rats and humans was also performed successfully by this method. Because the proposed method provides good precision and trace detection of HA in hair, the analytical technique seems to be applicable for the determination of various biogenic amines in hair.

Animals↗