Biomedical subjects

Masatoshi Nakamura

Publications and source records attributed to Masatoshi Nakamura.

16 recordsLinked to original sources

PubMed2006

C-prolinylquercetins from the yellow cocoon shell of the silkworm, Bombyx mori.

Two flavonoids containing the l-proline moiety, 6-C-[(2S,5S)-prolin-5-yl] quercetin (prolinalin A) and 6-C-[(2S,5R)-prolin-5-yl] quercetin (prolinalin B), were isolated from the cocoon shell of the silkworm, Bombyx mori. Their structural elucidation was achieved by application of acid hydrolysis and spectroscopic methods. These compounds were not found in the leaves of mulberry (Morus alba L.), the host plant of the silkworm, suggesting that the flavonoids are metabolites of the insect. This is the first time that flavonoids with an amino acid moiety have been found as naturally occurring compounds.

Animals↗

PubMed2006

Mulberry latex rich in antidiabetic sugar-mimic alkaloids forces dieting on caterpillars.

Since ancient times, mulberry leaves (Morus spp.) have been used to rear the silkworm Bombyx mori. Because the silkworm grows well on mulberry leaves, the toxicities and defensive activities of these leaves against herbivorous insects have been overlooked. Here we show that mulberry leaves are highly toxic to caterpillars other than the silkworm B. mori, because of the ingredients of the latex, a milky sap exuded from mulberry leaf veins. The toxicity of mulberry leaves was lost when the latex was eliminated from the leaves, and artificial diets containing latex showed toxicity. Mulberry latex contained very high concentrations of alkaloidal sugar-mimic glycosidase inhibitors reported to have antidiabetic activities, such as 1,4-dideoxy-1,4-imino-D-arabinitol, 1-deoxynojirimycin, and 1,4-dideoxy-1,4-imino-D-ribitol. The overall concentrations of these inhibitors in latex reached 1.5-2.5% (8-18% dry weight) in several mulberry varieties, which were approximately 100 times the concentrations previously reported from whole mulberry leaves. These sugar-mimic alkaloids were toxic to caterpillars but not to the silkworm B. mori, indicating that the silkworm can circumvent the mulberry tree's defense. Our results suggest that latex ingredients play key roles in defense of this tree and of other plants against insect herbivory, and they imply that plant latexes are treasuries of bioactive substances useful as medicines and pesticides.

1-Deoxynojirimycin↗

PubMed2006

Numerical estimation of heat distribution from the implantable battery system of an undulation pump LVAD.

We have been developing an implantable battery system using three series-connected lithium ion batteries having an energy capacity of 1,800 mAh to drive an undulation pump left ventricular assist device. However, the lithium ion battery undergoes an exothermic reaction during the discharge phase, and the temperature rise of the lithium ion battery is a critical issue for implantation usage. Heat generation in the lithium ion battery depends on the intensity of the discharge current, and we obtained a relationship between the heat flow from the lithium ion battery q(c)(I) and the intensity of the discharge current I as q(c)(I) = 0.63 x I (W) in in vitro experiments. The temperature distribution of the implantable battery system was estimated by means of three-dimentional finite-element method (FEM) heat transfer analysis using the heat flow function q(c)(I), and we also measured the temperature rise of the implantable battery system in in vitro experiments to conduct verification of the estimation. The maximum temperatures of the lithium ion battery and the implantable battery case were measured as 52.2 degrees C and 41.1 degrees C, respectively. The estimated result of temperature distribution of the implantable battery system agreed well with the measured results using thermography. In conclusion, FEM heat transfer analysis is promising as a tool to estimate the temperature of the implantable lithium ion battery system under any pump current without the need for animal experiments, and it is a convenient tool for optimization of heat transfer characteristics of the implantable battery system.

Electric Power Supplies↗

PubMed2006

Neural network-based hybrid human-in-the-loop control for meal assistance orthosis.

In order to assist some elderly and disabled people, who have partly or completely lost the ability of moving their upper limbs due to neurological disabilities or spinal cord disease, to take meals by themselves independently, a new type of meal assistance orthosis was recently developed. This paper presents a neural network-based hybrid human-in-the-loop control for this meal assistance orthosis with functional and safety purposes. In this approach, the position control and the force-free control are integrated into a single controller based on the model of meal assistance orthosis. By means of the position control, the meal assistance orthosis is controlled to generate appropriate compensation forces for assisting the movement of upper limb. In order to reduce the risk of hurting the bodies of human end-users and of damaging the device due to the impact from large external forces, with the force-free control, the meal assistance orthosis can flexibly move with the driven of large external forces. In addition, the controller of the meal assistance orthosis can be smoothly switched between the position control and the force-free control through a designed process to avoid instantaneously generating large external force owing to hard switching. In order to improve the adaptability of the proposed approach to different subjects, neural networks are adopted in the controller. Moreover, the proposed approach fully takes into account the influence of external forces induced by upper limb in the control process to form a kind of human-in-the-loop control. With the simulation and experiment of the meal assistance orthosis, the effectiveness of the proposed method was verified.

Algorithms↗

PubMed2006

Development of integrated electronics unit for drive and control of undulation pump-left ventricular assist device.

In this study, we have developed an implantable electronics unit (IEU) for driving an undulation pump-left ventricular assist device (UP-LVAD). The IEU consists of a pump driver, three series-connected lithium ion batteries (1800 mAh), a charger, and a transcutaneous information transmission system. These electronic subunits were encapsulated in a case (110 x approximately 80 x approximately 30 mm) made of epoxy resin. The IEU was evaluated in two animal experiments using goats implanted with the UP-LVAD. The lithium ion batteries in the IEU provided 30-min energy supply daily to the UP-LVAD. The transcutaneous information transmission system transmitted data bidirectionally between the IEU and the personal computer at the data transmission ratio of 56 kbps without any transmission error. We could obtain survival days of 27 and 28 days supporting cardiac function with the UP-LVAD system. The temperature inside the IEU case was maintained under 45 degrees C, and there was evidence of a burn on the surrounding tissue in autopsies in each experiment. Based on the results, the IEU is promising to be suitable for drive and control of an implantable UP-LVAD.

Animals↗

PubMed2006

Partial purification and some properties of a phospholipase C from Pseudomonas sp. strain KS3.2.

An extracellular phospholipase C was partially purified from Pseudomonas sp. strain KS3.2. The enzyme was composed of an approximately 18-kDa peptide. Maximal enzyme activity was found at pH 7.2 and 50 degrees C. The enzyme retained activity between pH 8 and 9, and 50% activity at about 52 degrees C for 30 min. The enzyme sample showed the highest activity on phosphatidylcholine and low activity toward other phospholipids.

Electrophoresis, Polyacrylamide Gel↗

PubMed2005

Technical quality evaluation of EEG recording based on electroencephalographers' knowledge.

The aim of this study is to develop a technical quality evaluation system of electroencephalogram (EEG) recording in order to acquire technically satisfactory EEG records, which may contribute to the accuracy improvement of EEG interpretation. In our developed system, the evaluation of EEG recording comprises the detection of technical artifacts and physiological status, which indicates the recording status objectively. In addition, the caution signals to users are generated in the system according to the undesired status detected. The information displayed to users includes the updated EEG records and instant evaluation results. Two examples of evaluation results are introduced in this paper, illustrating unsatisfactory records and artifact free records, respectively. The experimental results are proposed to verify the effectiveness of the technical quality evaluation of EEG recording. The implementation of the technical quality evaluation of EEG recording is helpful to acquire technically satisfactory EEG records, which may improve the accuracy of results in both the visual and the automatic EEG interpretation, and ease the laborious work of EEG technicians in the recording progress.

Adult↗

PubMed2004

Papain protects papaya trees from herbivorous insects: role of cysteine proteases in latex.

Many plants contain latex that exudes when leaves are damaged, and a number of proteins and enzymes have been found in it. The roles of those latex proteins and enzymes are as yet poorly understood. We found that papain, a cysteine protease in latex of the Papaya tree (Carica papaya, Caricaceae), is a crucial factor in the defense of the papaya tree against lepidopteran larvae such as oligophagous Samia ricini (Saturniidae) and two notorious polyphagous pests, Mamestra brassicae (Noctuidae) and Spodoptera litura (Noctuidae). Leaves of a number of laticiferous plants, including papaya and a wild fig, Ficus virgata (Moraceae), showed strong toxicity and growth inhibition against lepidopteran larvae, though no apparent toxic factors from these species have been reported. When the latex was washed off, the leaves of these lactiferous plants lost toxicity. Latexes of both papaya and the wild fig were rich in cysteine-protease activity. E-64, a cysteine protease-specific inhibitor, completely deprived the leaves of toxicity when painted on the surface of papaya and fig leaves. Cysteine proteases, such as papain, ficin, and bromelain, all showed toxicity. The results suggest that plant latex and the proteins in it, cysteine proteases in particular, provide plants with a general defense mechanism against herbivorous insects.

Animals↗

PubMed2003

Efficacy of real-time monitoring to determine motility in porcine small intestinal transplantation.

Orthotropic small intestinal transplantation (SIT) was performed in outbred 20 pigs. The interdigestive motor patterns were evaluated using strain gage (SG) force transducers. Seven pigs without SIT were treated as control (C) group. Based on the obtained data, the group, which could be detected the migrating motor complex (MMC) in the graft and alive with adequate oral feeding, was regarded as functional graft (FG) group, whereas the group which had available data recorded within 10 days before the death due to rejection was regarded as rejection (R) group. The MMC was analyzed using following parameters: duration; amplitude; and interval. In group FG, all parameters were almost same as group C, thus suggesting that the allograft in group FG had a normal motor function. In contrast, all parameters in group R were significantly lower than those in group FG, suggesting that the motility in group R was impaired. The SG method could monitor the real-time motility and was efficient for detecting the rejection of SIT.

Anastomosis, Surgical↗

PubMed2003

Effect of a nucleoside/nucleotide-free diet in rat allogenic small intestinal transplantation.

The aim of this study is to estimate the effect of nucleoside (NS) and nucleotide (NT) on the recipient and graft immune response after rat allogenic small intestinal transplantation. Seven-week-old Lewis rats were randomly assigned to two groups, including the NS/NT free group ( n=6) and the NS/NT supplemented group ( n=6), according to the diet received. The recipient Lewis rats were each given diet for 12 days, and then, on the nineteenth day of gestation, a 2 cm jejunum from the donor fetal Fischer rat was transplanted into the abdominal wall of the recipient rats using a non-vascular anastomotic technique. The recipient rats were killed on day 2 after transplantation, and then the recipient plasma interleukin-2 (IL-2) level was measured. In addition, the histological findings of the graft were analyzed. The IL-2 level of the NS/NT free group was significantly lower than that of the NS/NT supplemented group. In order to determine the grade of rejection, the morphological findings were blindly graded on a scale of 0-4. The mean grade of the NS/NT free group was also significantly lower than that of the NS/NT supplemented group. The NS/NT free diet is therefore considered to have an immunosuppressive effect on rat allogenic small intestinal transplantation based on the recipient plasma IL-2 levels and the histological findings of the grafts.

Abdominal Wall↗

PubMed2003

Cortisol and cytokine responses after surgery in different age groups of pediatric patients.

We investigated the cortisol and cytokine responses to surgical stress in the different age groups of pediatric patients. This study included 19 neonates (0-6 days old, group I), 19 infants (1-11 months old, group II), and 20 pre-school children (1-5 years old, group III), undergoing major thoracic and abdominal surgery. We obtained blood samples preoperatively and 0, 3, 6, 12, and 24 h postoperatively to measure the plasma levels of C-reactive protein (CRP), cortisol, interleukin (IL)-6, and IL-10. The plasma CRP level in each group reached a peak value on postoperative day 2; however, the peak value was significantly lower in group I than in groups II or III (I vs II, III; p=0.0134, p=0.0017, respectively). The plasma cortisol level in each group reached a peak value just after surgery; however, the peak value was also significantly lower in group I than in groups II or III (I vs II, III; p<0.001, p=0.0104, respectively). The plasma IL-6 level in each group reached a peak level hours postoperatively; however, the peak values in groups I and II were higher than in group III (I, II vs III; p=0.003, p=0.0458, respectively). The plasma IL-10 level in each group reached a peak value just after surgery and did not differ among the three groups. The endocrine and cytokine responses to the surgical stress vary among the different age groups of pediatric patients.

Age Factors↗

PubMed2003

The efficacy of autologous cord-blood transfusions in neonatal surgical patients.

PURPOSE: Allogenic blood transfusions have a risk of infection owing to unknown organisms, graft-versus-host reaction, and immunosupression; however, the use of autologous blood has been reported to be safe. Cord blood has been reported to be useful as a source of stem cell transplantation for the treatment of leukemia and genetic disease. Furthermore, autologous cord-blood transfusions (ACBT) have been reported to be effective for the treatment of anemia in premature infants. The authors examined the efficacy of ACBT in neonatal surgical patients. METHODS: Autologous cord-blood was stored from 12 infants at delivery, including 2 transvaginal and 10 cesarean section deliveries, from 1998 to 2001. All infants had surgically correctable malformations diagnosed antenatally. The mean gestational age was 37.2 +/- 1.6 weeks, and the birth weight was 2,597 +/- 1.6 g. The results of the blood count, serum electrolyte, and liver function tests of the patients who underwent ACBT only (group 1, n = 7) were compared with those of the 7 neonates who underwent an allogenic transfusion during the same period (group 2, n = 7). RESULTS: The mean volume of the stored blood was 64 +/- 35.6 g (range, 20 to 100). Eleven of the 12 patients underwent transfusions. Ten of 11 patients received autologous cord blood. A mean of 44.1 +/- 37.3 g of cord blood was used. Three of 10 cases also required an allotransfusion because of ECMO circuit preparation and a shortage of the stored blood. One patient underwent allotransfusion only. As a result, 7 of 11 babies (64%) who required transfusion were able to avoid an allotransfusion. The blood potassium levels were lower in group 1 than in group 2. No significant complications were recognized clinically. CONCLUSIONS: ACBT is considered beneficial because it enables neonatal surgical patients to avoid allotransfusions. Therefore, autologous cord-blood storage should be considered in the patients antenatally diagnosed to have surgical malformations. However, the storage volume varies for each case. Improved techniques to obtain an adequate amount of blood also should be developed.

Blood Loss, Surgical↗

PubMed2002

Regulation of glutamine metabolism during the development of Bombyx mori larvae.

Waste ammonia is re-assimilated into amino acids via the amide group of glutamine and the amino group of glutamate (i.e. through glutamine synthetase/glutamate synthase pathway) for silk synthesis in the silkworm, Bombyx mori, in the last larval stadium. Glutamine concentration in hemolymph gradually decreased with the progress of the fifth instar and it remained at very low levels during the spinning stage, then followed by a sharp increase at the larval-pupal ecdysis. The changes in glutamine synthetase (GS) activity in silkworm tissues were relatively small through the larval development, while the changes in glutamate synthase (GOGAT) activity, especially in the posterior silk glands, were more drastic. In addition, activities of GOGAT in the tissues were much higher than those of the other enzymes involved in glutamine utilization, suggesting that glutamine pool was regulated mainly by the changes in GOGAT activity. Western blot analysis indicated that the changes in GOGAT protein level correlated with the changes in GOGAT activity. Topical application of a juvenile hormone analogue, methoprene, induced an accumulation of glutamine in the hemolymph of the fifth instar larvae. The levels of GOGAT protein and activity in the tissues of the methoprene treated larvae were much lower than those of the control larvae, whereas the methoprene treatment had no effect on the levels of GS activity. In conclusion, GOGAT expression promoted by reduction of juvenile hormone titer is quite important for enhanced utilization of nitrogen for synthesis of silk protein during the last larval instar.

Animals↗

PubMed2002

Changing profile of parenteral nutrition in pediatric surgery: a 30-year experience at one institute.

BACKGROUND: Due to technical refinements and steady advances in the development of highly sophisticated nutrient solutions consisting of optimal combinations of macronutrients and micronutrients, parenteral nutrition (PN) is now playing an important role in patient management. However, some PN-associated complications, such as catheter-related sepsis (CRS) and cholestasis, continue at high incidence, particularly in neonates. The objective of this study was to investigate the changing profiles of PN over the past 30 years in our department. METHODS: The medical records of 893 children (225 neonates, 245 infants, 261 preschool-age children, and 162 school-age children) who were placed on PN for >7 days in our department were reviewed, and the following data were extracted: birth weight, underlying disease, indications for PN, PN delivery route, type of catheter used, duration of PN, substrate and energy intake, type of amino acid solution used, and incidence of complications including CRS and liver dysfunction. The results were analyzed by dividing the patients into 3 groups according to their basic stages in management of PN and consisted of group 1 (1970 to 1979), group 2 (1980 to 1989), and group 3 (1990 to 1999). The parameters were compared in each group. RESULTS: The total number of patients in each group showed no significant difference; however, the percentage of low birth-weight neonates increased in group 3. In group 1, 85% of PN was administered through the peripheral vein; in group 2, 51.2%; and in group 3, 9.7%. The total calorie and nutrient intake decreased in groups 2 and 3 compared with group 1, particularly regarding fat intake. In groups 1 and 2, commercially available amino acid solution based on the Food and Agriculture Organization/World Health Organization formula was usually used as the nitrogen source, but in group 3, it was changed to an amino acid solution for children. CRS decreased significantly, particularly in neonates, and occurred at a rate of 45.4% in group 1, 10.7% in group 2, and 1.5% in group 3. The incidence of liver dysfunction also showed a decrease: 35.7% in group 1, 22.3% in group 2, and 18.0% in group 3. A multivariate analysis showed a strong relationship between PN-related liver dysfunction and the duration of PN, the presence of infection, and the type of amino acid solution used. CONCLUSIONS: PN via central venous catheters has been regarded as safe and effective treatment in pediatric surgical patients. Over the past 30 years, the incidence of CRS has decreased. However, PN-related liver dysfunction remains a problem, particularly in patients receiving long-term PN.

Amino Acids↗

PubMed2002

Adaptive EEG spike detection: determination of threshold values based on conditional probability.

Determination of the threshold value for automatic EEG spike detection was investigated adopting conditional probability. An adaptive spike detection method was constructed and evaluated. A discriminant function for detecting spikes was obtained by conditional probability calculated from the EEG spike data. The relationship among false-negatives, false-positives and threshold values for the discriminant function was investigated. An adaptive detection algorithm was developed by combining different threshold values. False-negative and false-positive rates for spike detection depended on the threshold values. The adaptive spike detection algorithm achieved a high detection rate and accuracy. The advantage of the proposed method is to construct an adaptive detection algorithm by combining the threshold values according to the purpose of spike detection. Since the threshold can be easily changed in the proposed method, it is practically effective for clinical use.

Adult↗

PubMed2002

Microbial degradation of lipid by Acinetobacter sp. strain SOD-1.

Acinetobacter sp. strain SOD-1, capable of rapidly degrading salad oil, was isolated from soil. Strain SOD-1 showed good growth and degraded 68.7+/-2.7 and 83.0% of an initial 3000 ppm salad oil suspension in 24 h at 20 degrees C and pH 7.0 and at 35 degrees C and pH 8.0, respectively. The degradation rate depended on pH, temperature, phosphate concentration, and initial cell density.

Acinetobacter↗