Biomedical subjects

Masaki Yamaguchi

Publications and source records attributed to Masaki Yamaguchi.

13 recordsLinked to original sources

PubMed2006

Correlation of haloperidol levels between submandibular saliva and brain in the rat.

OBJECTIVE: The clinical usefulness of therapeutic drug monitoring (TDM) for haloperidol using blood samples has to be validated. Despite the potential advantage of TDM using saliva, there are few reports comparing drug levels in saliva and blood. Additionally, the relation between haloperidol levels in saliva and brain, the target organ of this drug, has not been reported. We compared haloperidol levels in rat submandibular saliva, plasma and brain. DESIGN: Haloperidol was administered through the femoral vein (0.25 mg/kg). Submandibular saliva was collected 30 min after drug administration. To stimulate secretion, the chorda (parasympathetic) and superior cervical ganglion (sympathetic) were electrically stimulated, and pilocarpine was administered. The concentration of haloperidol in saliva, plasma and brain homogenate was determined. RESULTS: Haloperidol levels in saliva elicited by any stimuli significantly correlated with levels in the brain and plasma. The correlation of haloperidol between saliva and brain was higher than that between plasma and brain. Immunohistochemistry showed that haloperidol was secreted from striated duct cells within the submandibular gland. CONCLUSION: These results suggested that haloperidol was specifically secreted from the striated duct system, and that salivary drug levels reflect the levels in the brain more precisely than plasma.

Animals↗

PubMed2006

Hand-held monitor of sympathetic nervous system using salivary amylase activity and its validation by driver fatigue assessment.

In order to realize a hand-held monitor of the sympathetic nervous system, we fabricated a completely automated analytical system for salivary amylase activity using a dry-chemistry system. This was made possible by the fabrication of a disposable test-strip equipped with built-in collecting and reagent papers and an automatic saliva transfer device. In order to cancel out the effects of variations in environmental temperature and pH of saliva, temperature- and pH-adjusted equations were experimentally determined, and each theoretical value was input into the memory of the hand-held monitor. Within a range of salivary amylase activity between 10 and 140 kU/l, the calibration curve for the hand-held monitor showed a coefficient with R(2)=0.97. Accordingly, it was demonstrated that the hand-held monitor enabled a user to automatically measure the salivary amylase activity with high accuracy with only 30 microl sample of saliva within a minute from collection to completion of the measurement. In order to make individual variations of salivary amylase activity negligible during driver fatigue assessment, a normalized equation was proposed. The normalized salivary amylase activity correlated with the mental and physical fatigue states. Thus, this study demonstrated that an excellent hand-held monitor with an algorithm for normalization of individuals' differences in salivary amylase activity, which could be easily and quickly used for evaluating the activity of the sympathetic nervous system at any time. Furthermore, it is suggested that the salivary amylase activity might be used as a better index for psychological research.

Adult↗

PubMed2006

Successful treatment of refractory peripheral T-cell lymphoma with a combination of fludarabine and cyclophosphamide.

We report a case of refractory peripheral T-cell lymphoma (PTCL) successfully treated with a combination of fludarabine and cyclophosphamide (FLU/CY). A 68-year-old man with concurrent PTCL and diffuse large B-cell lymphoma was treated effectively with 3-course CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone) therapy, but PTCL relapse occurred and was resistant to ESHAP (etoposide, methylprednisolone, cytarabine, and cisplatin) therapy. FLU/CY therapy led to complete remission, which was maintained for almost 14 months after a single course. We concluded that a FLU/CY regimen may be useful for attaining long-term remission in patients with refractory relapsed PTCL and should therefore be considered a valuable treatment choice.

Aged↗

PubMed2005

Long-term remission of blastic natural killer-cell lymphoma after autologous peripheral blood stem-cell transplantation.

We report here a case of blastic natural killer (NK)-cell lymphoma treated successfully with autologous peripheral blood stem-cell transplantation (APBSCT). A 57-year-old man had skin tumors and was diagnosed as having blastic NK-cell lymphoma by tumor biopsy. Skin, lymph nodes, left tonsil, and bone marrow were involved at presentation. Chemotherapy led to complete remission (CR). To sustain CR, the patient underwent high-dose chemotherapy in combination with 12 Gy of total-body irradiation (TBI) followed by autologous peripheral blood stem-cell rescue. He showed rapid recovery of hematopoiesis and could tolerate regimen-related toxicity after APBSCT. He has maintained long-term remission for 20 months after APBSCT. From this case, we concluded that APBSCT with preconditioning by TBI-containing regimens might be a cure-attaining treatment for disseminated blastic NK-cell lymphoma and should be considered as a choice of treatment in cases where no suitable donors for allogeneic transplantation are available.

Blast Crisis↗

PubMed2005

Flat-chip microanalytical enzyme sensor for salivary amylase activity.

It is considered that measurement of salivary alpha-amylase activity is a useful tool for evaluating the sympathetic nervous system. The purpose of this research is to demonstrate a new design of a flat-chip microanalytical enzyme sensor (flat-chip sensor) for salivary amylase activity as a Micro-Electro-Mechanical Systems (MEMS), which may be used for wearable analytical systems. To meet this purpose, the biosensor needs to be miniaturized and to possess high-sensitivity. A pre-column and a flat-enzyme electrode were incorporated in a flow cell of volume 25.7 ml. In order to miniaturize the flow cell, two enzymatic membranes containing maltose phosphorylase obtained from Enterococcus hirae (MP membrane) and glucose oxidase and peroxidase (GOD-POD membrane) were immobilised on the same planar surface. As a result, a flat-chip sensor incorporating a flow cell as small as a C battery was produced. The optimum conditions of three parameters of the fabricated flat-chip sensor, the immobilising method of the enzymatic membrane, dropping volume of the mixed enzymatic solution and flow rate of the sample solution, were examined. An analytical system for 0-190 kU/l amylase activity with R(2) of 0.97 was fabricated with a sample volume of 50 microl. This research indicates the possibility of a wearable biosensor for continuous monitoring of salivary amylase activity.

Biosensing Techniques↗

PubMed2005

Evaluation of time-course changes of gingival crevicular fluid glucose levels in diabetics.

A minute volume such as a few hundred nano-litres of gingival crevicular fluid (GCF) will evaporate within one minute at room temperature after collection. In order to investigate the feasibility of a method for noninvasive blood glucose measurement using this fluid, a fabricated GCF-collecting device, and the time-course changes of blood and GCF glucose levels in diabetics were evaluated. As a result of improvement in the GCF-collecting device such that the color of a filter paper changed from white to black upon collection of the sample, the completion of the collecting procedure could be visually confirmed. Using this device, we succeeded in collecting 200 nl of GCF within 30 s, despite the fact that GCF is usually secreted at a rate between 2 and 3 microl per tooth per hour. This method could be applicable for collecting small volume of other biological fluids. The time-course changes of blood and GCF glucose levels in ten type 2 diabetic subjects were examined, the correlation coefficient, R, between both glucose levels was 0.878. The result proved to be similar to that for normal healthy subjects in a previous study. A significant time difference between the two glucose levels was not observed. In diabetes period of 4.8 +/- 1.7 years, the influence of the disease on the GCF glucose level was minimal. Furthermore, from the ROC curve analysis, both sensitivity and specificity showed favorable results. It was suggested that the measurement of GCF glucose levels was a promising screening method for diabetics.

Blood Chemical Analysis↗

PubMed2005

Error grid analysis of noninvasive glucose monitoring via gingival crevicular fluid.

In order to realize a noninvasive blood glucose monitor, we monitored the gingival crevicular fluid (GCF). In this paper, the clinical evaluations were performed on not only normal subjects but also diabetic subjects using a GCF-glucose monitor to determine blood glucose levels. Meal load tests were carried out and the time-course changes in blood glucose level and GCF glucose level were measured continuously. A positive correlation of more than 0.9 was found between blood glucose level and GCF glucose level, necessitating the calibration of individual correlations for every subject. Finally, the performance of the GCF-glucose monitor was evaluated using Error Grid Analysis. As the results, significant information for the glucose level decision was obtained not only for normal subjects, but also for diabetic subjects.

Adult↗

PubMed2004

Point of care testing system via enzymatic method for the rapid, efficient assay of glycated albumin.

The ratio of glycated albumin to albumin concentration in serum is termed the glycated albumin (GA) value. The GA value provides a time-averaged index of the state of glycemic control for the previous 2 weeks. In this study, a dry chemistry system (GA monitor) via an enzymatic method was proposed in order to provide a GA value measurement for point of care testing (POCT). The GA monitor was made from three devices a set of test-tapes, a test-strip and an optical analyzer. A GA test-tape, a ketoamine test-tape and an albumin test-tape were enclosed in the fabricated test-strip. Time-course changes of the optical characteristics were evaluated using the test-strip. It was found that the three test tapes must be enclosed in the test-strip to create a dry chemistry system for small sample volumes (20 microl). A temperature control unit, which could hold the temperature of the GA test-tape at 45 degrees C and at 25 degrees C for the other two types of test-tape was incorporated into the optical analyzer. With the GA test-tape held separately and controlled at 45 degrees C, the analytical time decreased to one-third of the time taken for the three tapes at 25 degrees C. The analytical accuracy of the three types of test-tape showed favorable results, with R2 values of 0.96-0.98 and coefficients of variation (CV) of 2.4-6.8%. Compared with a commercially available liquid chemistry system, the analytical accuracy of the GA monitor exhibited a relatively favorable linearity of R=0.82. According to these results, a new GA value analytical system was realized, in which the GA value could be assayed within five minutes using only 20 microl of blood sample with a disposable test-strip. This system could potentially be used for clinical purposes as test equipment for rapid and efficient POCT.

Biomarkers↗

PubMed2004

Performance evaluation of salivary amylase activity monitor.

In order to quantify psychological stress and to distinguish eustress and distress, we have been investigating the establishment of a method that can quantify salivary amylase activity (SMA). Salivary glands not only act as amplifiers of a low level of norepinephrine, but also respond more quickly and sensitively to psychological stress than cortisol levels. Moreover, the time-course changes of the salivary amylase activity have a possibility to distinguish eustress and distress. Thus, salivary amylase activity can be utilized as an excellent index for psychological stress. However, in dry chemistry system, a method for quantification of the enzymatic activity still needs to be established that can provide with sufficient substrate in a testing tape as well as can control enzymatic reaction time. Moreover, it is necessary to develop a method that has the advantages of using saliva, such as ease of collection, rapidity of response, and able to use at any time. In order to establish an easy method to monitor the salivary amylase activity, a salivary transcription device was fabricated to control the enzymatic reaction time. A fabricated salivary amylase activity monitor consisted of three devices, the salivary transcription device, a testing-strip and an optical analyzer. By adding maltose as a competitive inhibitor to a substrate Ga1-G2-CNP, a broad-range activity testing-strip was fabricated that could measure the salivary amylase activity with a range of 0-200 kU/l within 150 s. The calibration curve of the monitor for the salivary amylase activity showed R2=0.941, indicating that it was possible to use this monitor for the analysis of the salivary amylase activity without the need to determine the salivary volume quantitatively. In order to evaluate the assay variability of the monitor, salivary amylase activity was measured using Kraepelin psychodiagnostic test as a psychological stressor. A significant difference of salivary amylase activity was recognized between the pre-stress and mid-stress periods. This study demonstrated that broad-range salivary amylase activity monitor was developed that could be used with only 5 microl of saliva.

Adult↗

PubMed2004

Effect of psychological stress on the salivary cortisol and amylase levels in healthy young adults.

OBJECTIVE: Saliva sampling has the advantage that it is non-invasive, making multiple sampling easy and stress free. We examined the effects of psychological stressor and soother on the salivary cortisol and amylase levels in young adults, and compared the characteristics of these parameters. DESIGN: The subjects completed the trait version of State-Trait Anxiety Inventory (STAI) to assess the predisposition to personal anxiety. The video of corneal transplant surgery was served as the stressor for 15 min. A scenic beauty video viewing was also used as the soother. Unstimulated whole saliva was collected every 3 min throughout the session. RESULTS: The amylase level was significantly increased just after the beginning of the stressful video viewing, and immediately returned to the pre-stress level just after the end of the video viewing. The cortisol level was also increased, but to a lesser extent compared with that of amylase. The latency time to the peak level for cortisol was longer than that of amylase. The carry-over effect was not observed in the amylase response but was in cortisol. Although the correlation between the amylase level and the STAI score was highly significant, cortisol level did not. In addition, soothing video viewing significantly decreased the amylase level, but did not affect the cortisol level. CONCLUSION: Salivary amylase level was more significantly increased and reacted more rapidly than cortisol by psychological stressor, suggesting that it is a better index of stress. Furthermore, it is suggested that the enzyme is a soothing or relaxation index.

Adult↗

PubMed2004

Proposal of blood-collecting needle approach to semi-invasive method.

Many diabetic patients carry a portable self-monitoring of blood glucose (SMBG)-analyzer in order to collect their own blood and examine their glucose levels; this allows them to determine such factors as insulin dose, diet and exercise to stay healthy. However, the test causes physical and mental stress for the subjects. The authors aim to develop a semi-invasive blood-collecting needle which does not need a power source for the pump mechanism. In this study, we fabricated a capillary action needle that can collect the blood sample automatically. A blood-collecting needle was fabricated from 25 gage sized medical needle (diameter of 0.5 mm, stainless steel) by cutting process, and it had a half-opened crevice in the tip. In order to evaluate the physical characteristics of the blood-collecting needle, the relationship between the size and suction time and/or suction volume were measured using an isotonic sodium chloride solution, whole rabbit blood, and whole human blood with anticoagulant. Next, in order to evaluate the degree of invasion, the diameters of erythema in auricles of rabbits were observed for 2 days using a CCD camera-type microscope. The mean suction time of the isotonic sodium chloride solution and the whole rabbit blood were 1.5 s (n = 10) and 9.0 s (n = 5), respectively. Selection of a suitable size of the blood-collecting needle enabled the collection of 0.1 microL of whole human blood in 10 s. Moreover, it was shown, by comparing the observed diameter of the erythema, that the invasiveness of the blood-collecting needle was smaller than for commercial needles of the equal diameter. It became clear that this fulfils the fundamental functions of a semi-invasive blood-collecting needle.

Adult↗

PubMed2003

Flow-injection-type biosensor system for salivary amylase activity.

The authors aim to establish a method that can quantitatively evaluate vital reactions to stress. We have been examining the correlation between stress and salivary amylase activity in order to verify its validity as a stress index. In order to quantify human stress, which changes over time, the relationship between stress and salivary amylase activity must be verified by fast and repeated analysis of salivary amylase activity. Standard biosensors are designed such that the enzyme immobilized on an electrode (enzyme electrode) and the substrate-dependent activity is measured. The reverse approach of measuring the alpha-amylase-dependent activity was adopted. We fabricated an amylase activity analytical system. Maltopentaose was selected as a substrate for alpha-amylase and a flow-injection-type device was used to supply maltopentaose continuously. alpha-Glucosidase, having relatively low enzyme activity, was immobilized on a pre-activated membrane so that it could be enclosed in a pre-column, Glucose oxidase, having higher enzyme activity, was immobilized on a working electrode so that it could function as an amperometric biosensor. A saliva-collecting device was fabricated to make saliva pretreatment unnecessary. As a result, an amylase activity analytical system was fabricated that enabled us to measure salivary amylase activity from 0 to 30 kU/l, with an R(2) value of 0.97. The time-course changes in the salivary amylase activities for 1 week were 5.1%, and the initial sensitivity remained nearly constant. Through this study, we were able to verify the possible development of the amylase activity analytical system.

Amylases↗

PubMed2002

Bactericidal activity of electrolyzed acid water from solution containing sodium chloride at low concentration, in comparison with that at high concentration.

Electrolyzed strong acid water (ESW) containing free chlorine at various concentrations is becoming to be available in clinical settings as a disinfectant. ESW is prepared by electrolysis of a NaCl solution, and has a corrosive activity against medical instruments. Although lower concentrations of NaCl and free chlorine are desired to eliminate corrosion, the germicidal effect of ESW with low NaCl and free-chlorine concentrations (ESW-L) has not been fully clarified. In this study, we demonstrated that ESW-L possesses bactericidal activity against Mycobacteria and spores of Bacillus subtilis. The effect was slightly weaker than that of ESW containing higher NaCl and free-chlorine concentrations (ESW-H), but acceptable as a disinfectant. To clarify the mechanism of the bactericidal activity, we investigated ESW-L-treated Pseudomonas aeruginosa by transmission electron microscopy, a bacterial enzyme assay and restriction fragment length polymorphism pattern (RFLP) assay. Since the bacterium, whose growth was completely inhibited by ESW-L, revealed the inactivation of cytoplasmic enzyme, blebs and breaks in its outer membrane and remained complete RFLP of DNA, damage of the outer membrane and inactivation of cytoplasmic enzyme are the important determinants of the bactericidal activity.

Bacillus subtilis↗