Biomedical subjects

T Matsukawa

Publications and source records attributed to T Matsukawa.

At least 19 recordsLinked to original sources

PubMed2006

Upregulation of retinal transglutaminase during the axonal elongation stage of goldfish optic nerve regeneration.

Fish CNS neurons can repair their axons following nerve injury, whereas mammalian CNS neurons cannot regenerate, and become apoptotic within 1-2 weeks after the nerve lesion. One explanation for these differences is that one, or several molecules are upregulated in fish CNS neurons during nerve regeneration, and this same molecule is downregulated in mammalian CNS neurons before the development of apoptosis caused by nerve injury. A molecule satisfying these criteria might successfully rescue and repair the mammalian CNS neurons. In this study, we looked for such a candidate molecule from goldfish retinas. Transglutaminase derived from goldfish retina (TG(R)) was characterized as a regenerating molecule after optic nerve injury. A full-length cDNA for TG(R) was isolated from the goldfish retinal cDNA library prepared from axotomized retinas. Levels of TG(R) mRNA and protein increased only in the retinal ganglion cells (RGCs) between 10 and 40 days after optic nerve transection. Recombinant TG(R) protein enhanced neurite outgrowth from adult fish RGCs in culture. Specific interference RNA and antibodies for TG(R) inhibited neurite outgrowth both in vitro and in vivo. In contrast, the level of TG(R) protein decreased in rat RGCs within 1-3 days after nerve injury. Furthermore, the addition of recombinant TG(R) to retinal cultures induced striking neurite outgrowth from adult rat RGCs. These molecular and cellular data strongly suggest that TG(R) promotes axonal elongation at the surface of injured RGCs after optic nerve injury.

Animals↗

PubMed2004

Is the ARX index a more sensitive indicator of anesthetic depth than the bispectral index during sevoflurane/nitrous oxide anesthesia?

BACKGROUND: During general anesthesia, hypnotic components have been monitored with electroencephalogram. The bispectral index is derived from a cortical electroencephalogram, but the A-line ARX index is the electroencephalographic response to auditory stimuli. The purpose of this study was to compare the changes of the A-line ARX index and the bispectral index during sevoflurane - nitrous oxide anesthesia. METHODS: One hundred females aged 30-60 years, and scheduled for partial mastectomy, were divided into two groups. Anesthesia was induced with sevoflurane 5% and nitrous oxide in oxygen for 3 min. A laryngeal mask airway was inserted, and anesthesia was maintained with sevoflurane 1-2% and nitrous oxide in oxygen. During surgery, the sevoflurane end-tidal concentration was kept at 0.5%, 1%, or 2% for 5 min before each measurement. Blood pressure, heart rate, and the A-line ARX index (n = 50), and the bispectral index (n = 50) were measured. RESULTS: Blood pressure and heart rate increased following laryngeal mask airway insertion and blood pressure decreased at 2% sevoflurane in both groups similarly. The A-line ARX index, but not the bispectral index, increased significantly by laryngeal mask airway insertion and skin incision. The A-line ARX index decreased at 2% sevoflurane compared with 0.5%, while the bispectral index remained unchanged. CONCLUSION: During sevoflurane-nitrous oxide anesthesia, the A-line ARX index might be a more sensitive indicator of anesthetic depth than the bispectral index.

Adult↗

PubMed2003

Preoperative blood pressure and catecholamines related to hypothermia during general anesthesia.

BACKGROUND: We previously demonstrated that preoperative blood pressure values affect intraoperative hypothermia during general anesthesia. We hypothesized that increased catecholamine secretion could be responsible for the relationship between preoperative blood pressure and hypothermia. METHODS: To evaluate the effect of preoperative systolic blood pressure (SBP) and plasma catecholamine levels on core temperature during general anesthesia, 40 male patients who were scheduled for open abdominal surgery were allocated to two groups: those whose preoperative SBP was 140 mmHg or greater (high SBP group, n = 20), and those whose SBP was less than 140 mmHg (normal SBP group, n = 20). Anesthesia was maintained with 0.4% isoflurane and opioids. RESULTS: The average age, height, and weight of the patients in the two groups did not differ. Preoperative SBP, mean blood pressure, diastolic blood pressure and heart rate in the high SBP group were significantly higher than those in the normal SBP group. Plasma norepinephrine concentrations in the high SBP group were significantly greater than those in the normal SBP group before and 1 h after the induction of anesthesia. Tympanic membrane temperatures in the normal SBP group started to decline further just after the induction of anesthesia, more so than that in the high SBP group. The vasoconstriction threshold in the normal SBP group was significantly lower than that in the high SBP group. CONCLUSION: These results suggest that the higher levels of preoperative catecholamine secretion contributed to the lesser degree of intraoperative hypothermia observed in the high SBP group.

Abdomen↗

PubMed2003

The vasoconstriction threshold is increased in obese patients during general anaesthesia.

BACKGROUND: In anaesthetized patients, body temperature decreases often, but overweight patients become less hypothermic. Obesity in itself protects body heat, and thermoregulatory reflexes may maintain normothermia in obese patients. We tested the hypothesis that even slight obesity increases the vasoconstriction threshold. METHODS: Twenty male patients aged 30-65 years scheduled for open abdominal surgery were allocated to two groups: body fat >/=25% (obese group, n = 10), or <25% (normal weight group, n = 10). Anaesthesia was maintained with 0.4% isoflurane and opioid. The thermoregulatory vasoconstriction threshold was defined by the tympanic membrane temperature at which the skin temperature gradient equalled 0 degrees C. Plasma adrenaline, noradrenaline and leptin were measured. RESULTS: Age, height, heart rate and blood pressure did not differ between the two groups of patients. In the obese group the vasoconstriction threshold was higher than that in the normal weight group: 36.0 +/- 0.1 vs. 35.5 +/- 0.2 degrees C. Consequently, after 4 h of anaesthesia, the core temperature was highest in the obese patients: 36.4 +/- 0.1 vs. 35.5 +/- 0.2 degrees C. CONCLUSIONS: These results suggest that core temperature is maintained in obese patients because their vasoconstriction threshold to a low environmental temperature is high.

Adult↗

PubMed2003

Warming by resistive heating maintains perioperative normothermia as well as forced air heating.

BACKGROUND: Even mild perioperative hypothermia is associated with several severe adverse effects. Resistive heating has possible advantages compared with other active warming systems because it can heat several fields independently. To assess this new warming system, we measured core temperature in patients during surgery who were warmed with circulating water mattresses, forced air covers or resistive heating covers. METHODS: Twenty-four patients undergoing laparoscopic cholecystectomy were randomly assigned to (i) circulating water mattress (38 degrees C), (ii) forced air warming (set to 'medium') or (iii) carbon-fibre resistive warming (38 degrees C). Warming was applied throughout anaesthesia and surgery. The groups were compared using one-way ANOVA and Student-Newman-Keuls tests. RESULTS: Confounding factors were similar among the groups. Core temperatures in each group decreased for 20 min, but subsequently increased in the forced air and resistive heating groups. There was no significant difference between the forced air and resistive heating groups at any time. In contrast, core temperature in the circulating water group continued to decrease. Consequently, core temperature in the circulating water group was significantly lower than in the other groups 30 min after anaesthetic induction and at later times. CONCLUSIONS: Resistive heating maintains core body temperature as well as forced air heating and both are better than circulating water. Resistive heating offers the advantage of adjustable heating pods.

Adult↗

PubMed2003

Effect of preoperative amino acid infusion on thermoregulatory response during spinal anaesthesia.

BACKGROUND: Intravenous amino acid infusion during general anaesthesia prevents decreases in core temperature resulting from increased energy expenditure and heat accumulation. METHODS: We investigated whether such stimulation also occurs during spinal anaesthesia, which blocks sympathetic nervous activity. We examined the effect of i.v. amino acid infusion on changes in core temperature during spinal anaesthesia. Thirty-five patients were divided into two groups: an i.v. amino acid infusion group (4 kJ kg(-1) h(-1) starting 2 h before surgery); and a saline infusion group. Tympanic membrane core temperature, forearm-fingertip temperature gradient (an index of peripheral vasoconstriction) and mean skin temperature were measured for 90 min after the onset of spinal anaesthesia. RESULTS: Changes in mean arterial pressure and heart rate did not differ significantly between the groups during the study period. Mean final core temperature 90 min after induction of spinal anaesthesia was 35.8 (SEM 0.1) degrees C in the saline group and 36.6 (0.1) degrees C in the amino acid group (P<0.05). The increased level of oxygen consumption in the amino acid group compared with the saline group was preserved even after the onset of spinal anaesthesia. The thermal vasoconstriction threshold, defined as the tympanic membrane temperature that triggered a rapid increase in forearm-fingertip temperature gradient, was increased in the amino acid group [36.8 (0.1) degrees C] compared with the saline group [36.5 (0.1) degrees C] (P<0.05). CONCLUSIONS: Preoperative infusion of amino acids effectively prevents spinal anaesthesia-induced hypothermia by maintaining a higher metabolic rate and increasing the threshold core temperature for thermal vasoconstriction.

Adult↗

PubMed2003

Nitrous oxide decreases shivering threshold in rabbits less than isoflurane.

BACKGROUND: Comparable minimum alveolar concentration (MAC) fractions of volatile anaesthetics produce similar thermoregulatory impairment. Nitrous oxide, however, decreases the vasoconstriction threshold less than sevoflurane or isoflurane. We tested the hypothesis that nitrous oxide also decreases shivering threshold less than isoflurane alone or in combination. METHODS: Twenty-four rabbits were assigned randomly to one of three 0.3 MAC anaesthetic regimens: (i) nitrous oxide 69%; (ii) nitrous oxide 35% and isoflurane 0.3%; or (iii) isoflurane 0.6%. Body temperature was lowered by perfusing 10 degrees C water through a U-shaped thermode positioned in the colon. Shivering was evaluated by inspection. RESULTS: The rabbits anaesthetized with nitrous oxide alone shivered at 37.0 (0.5) degrees C (P<0.01 vs other groups). In those given the nitrous oxide and isoflurane combination, the shivering threshold was 36.4 (0.5) degrees C and that in the isoflurane group was 35.9 (0.4) degrees C. CONCLUSION: This study indicates that nitrous oxide reduces the shivering threshold less than isoflurane.

Anesthetics, Inhalation↗

PubMed2002

Measurements of cosmic-ray low-energy antiproton and proton spectra in a transient period of solar field reversal.

The energy spectra of cosmic-ray low-energy antiprotons ( *p's) and protons ( p's) have been measured by BESS in 1999 and 2000, during a period covering reversal at the solar magnetic field. Based on these measurements, a sudden increase of the *p/p flux ratio following the solar magnetic field reversal was observed, and it generally agrees with a drift model of the solar modulation.

Journal Article↗

PubMed2002

Propofol in low doses causes redistribution of body heat in male volunteers.

BACKGROUND AND OBJECTIVE: Cardiovascular and mental stress in dental patients with phobias about dentistry may be reduced by propofol sedation. We tested the hypothesis that even low doses of propofol may have effects on body temperatures in male volunteers. METHODS: Six healthy male volunteers were given propofol over 28 min with the following infusion rates: 8 mg kg(-1) h(-1) for the first 3 min, 4 mg kg(-1) h(-1) for the next 10 min, and 2 mg kg(-1) h(-1) for the final 15 min. Body temperatures were measured at five locations: tympanic membrane, forehead, forearm, dorsum of the hand and fingertip. Thermoregulatory vasoconstriction was evaluated using the forearm minus fingertip temperature gradient. RESULTS: Tympanic membrane and forehead temperatures began to decrease at 10 and 20 min, respectively, after the start of the propofol infusion, and reached a minimum at 30 min (tympanic -0.5 +/- 0.2 degrees C) and 40 min (forehead -0.6 +/- 0.2 degrees C), respectively. Peripheral skin temperatures showed an increase between 10 and 30 min in the forearm and fingertip and between 20 and 30 min in the dorsum of the hand. After 30 min, a decrease in peripheral skin temperatures was observed. The forearm minus fingertip temperature gradient changed from negative to positive after 40 min, and increased continuously thereafter (baseline -0.3 +/- 0.4 degrees C, 90 min: 6.5 +/- 1.6 degrees C). CONCLUSIONS: A low dose of propofol impairs tonic thermoregulatory vasoconstriction and induces heat redistribution from the core to the periphery.

Adult↗

PubMed2002

Na,K-ATPase alpha3 subunit in the goldfish retina during optic nerve regeneration.

The goldfish optic nerve can regenerate after injury. To understand the molecular mechanism of optic nerve regrowth, we identified genes whose expression is specifically up-regulated during the early stage of optic nerve regeneration. A cDNA library constructed from goldfish retina 5 days after transection was screened by differential hybridization with cDNA probes derived from axotomized or normal retina. Of six cDNA clones isolated, one clone was identified as the Na,K-ATPase catalytic subunit alpha3 isoform by high- sequence homology. In northern hybridization, the expression level of the mRNA was significantly increased at 2 days and peaked at 5-10 days, and then gradually decreased and returned to control level by 45 days after optic nerve transection. Both in situ hybridization and immunohistochemical staining have revealed the location of this transient retinal change after optic nerve transection. The increased expression was observed only in the ganglion cell layer and optic nerve fiber layer at 5-20 days after optic nerve transection. In an explant culture system, neurite outgrowth from the retina 7 days after optic nerve transection was spontaneously promoted. A low concentration of ouabain (50-100 nm ) completely blocked the spontaneous neurite outgrowth from the lesioned retina. Together, these data indicate that up-regulation of the Na,K-ATPase alpha3 subunit is involved in the regrowth of ganglion cell axons after axotomy.

Amino Acid Sequence↗

PubMed2002

Preoperative risk factors of intraoperative hypothermia in major surgery under general anesthesia.

UNLABELLED: Preoperative factors, such as age and body habitus, affect intraoperative hypothermia during general anesthesia. In a preliminary study, we developed a logistic model to retrospectively evaluate predictors of intraoperative hypothermia in patients who received major surgery. The following factors were selected to develop the model: Z = -15.014 + 0.097 x (Age) + 0.263 x (Height) - 0.323 x (Weight) - 0.055 x (Preoperative systolic blood pressure) - 0.121 x (Preoperative heart rate). By using this model, the probability of hypothermia can be estimated by applying the following formula: Probability = 1/(1 + e(-)(Z)). If an estimated probability of hypothermia was >0.5, the sensibility of prediction was 81.5% and the specificity was 83%. In the second study, the model was applied prospectively to other patients, and the validity of the logistic model was evaluated. The core temperature showed a significant decrease in patients with a probability >0.7, who were predicted to be hypothermic, and their thermoregulatory vasoconstriction threshold also showed a significant decrease, compared with the patients with a probability <==0.3, who were predicted to be normothermic. We concluded that intraoperative hypothermia could be predicted from preoperative characteristics such as age, height, weight, systolic blood pressure, and heart rate. IMPLICATIONS: Increases in age and height and decreases in weight systolic blood pressure and heart rate are major preoperative risk factors of intraoperative hypothermia during major surgery.

Aged↗

PubMed2002

Alleviation of the two-cell block of ICR mouse embryos by polyaminocarboxylate metal chelators.

The present study was undertaken to examine the effects of various transition metal ion chelators, both polyaminocarboxylates (including nitrilotriacetate (NTA), ethylenediaminediacetate (EDDA), ethyleneglycolbistetraacetate (EGTA), ethylenediaminetetraacetate (EDTA) and diethylenetriaminepentaacetate (DTPA)) and non-polyaminocarboxylates (dipicolinic acid and deferoxamine), on the development in vitro of one-cell ICR strain mouse embryos to the four-cell and blastocyst stages. The order of stability constants of polyaminocarboxylates for transition metal ions such as zinc, copper and iron is as follows: NTA < or = EDDA < EGTA < EDTA < DTPA. Addition of 10 or 100 micromol polyaminocarboxylates x l(-1) to the medium significantly enhanced the development of most one-cell embryos (66-88%) beyond the two-cell stage compared with that (< 25%) in medium without polyaminocarboxylates. Although EDDA, EDTA and DTPA at 10 micromol x l(-1) induced the development of most one-cell embryos to the four-cell stage and beyond, a higher concentration (100 micromol x l(-1)) of NTA and EGTA was required to obtain a similar result. Therefore, the ability of polyaminocarboxylates to overcome the two-cell block is not correlated with their potency to chelate transition metal ions. In contrast, the non-polyaminocarboxylates dipicolinic acid and deferoxamine, at 10 and 100 micromol x l(-1), did not have the same effect. Taken together, the results indicate that the ability of polyaminocarboxylates to overcome the two-cell block in embryo development is due to some common feature or features other than the ability to chelate transition metal ions.

Animals↗

PubMed2001

A simple estimation of peroxisomal degradation with green fluorescent protein - an application for cell cycle analysis.

When nutrients are depleted from the environment, mammalian cells begin to degrade their own cytosol and organelles. This bulk protein degradation is mediated by autophagy. In this study, peroxisomes in living CHO-K1 cells were visualized by targeting the green fluorescent protein (GFP) tagged with a type 1 peroxisomal targeting signal. The nutrient-starved condition induced a decay of GFP fluorescence in the peroxisomes and autophagic inhibitors such as 3-methyladenine suppressed the decay of GFP fluorescence (13-60% of starvation). By double labeling the nuclear DNA and peroxisomal GFP, the autophagy specifically occurred at the G1 phase of the cell cycle and the autophagic inhibitors suppressed the G1 arrest. The vital stain technique with GFP is a very simple and useful marker to quantitatively estimate or to further study peroxisomal degradation.

Animals↗

PubMed2001

Gas chromatographic-mass spectrometric determination of alpha-ketoisocaproic acid and [2H7]alpha-ketoisocaproic acid in plasma after derivatization with N-phenyl-1,2-phenylenediamine.

A method for determination of alpha-ketoisocaproic acid (KIC) and [4,5,5,5,6,6,6-2H7]alpha-ketoisocaproic acid ([2H7]KIC) in rat plasma was developed using gas chromatography-mass spectrometry-selected ion monitoring (GC-MS-SIM). [5,5,5-2H3]alpha-Ketoisocaproic acid ([2H3]KIC) was used as an analytical internal standard to account for losses associated with the extraction, derivatization and chromatography. The keto acids were extracted by cation-exchange chromatography using BondElut SCX cartridge and derivatized with N-phenyl-1,2-phenylenediamine to form N-phenylquinoxalinone derivatives. Quantitation was performed by SIM of the respective molecular ions at m/z 278, 281 and 285 for the derivatives of KIC, [2H3]KIC and [2H7]KIC on the electron impact method. The limit of detection was found to be 70 fmol per injection (S/N=3) and the limit of quantitation for [2H7]KIC was around 50 nM in rat plasma. Endogenous KIC concentrations in 50 microl of rat plasma were measured with relative intra- and inter-day precision of 4.0% and 3.3%, respectively. The intra- and inter-day precision for [2H7]KIC spiked to rat plasma in the range of 0.1 to 10 microM gave good reproducibility with relative standard deviation (RSD) of 6.5% and 5.4%, respectively. The intra- and inter-day relative errors (RE) for [2H7]KIC were less than 6.4% and 3.8%, respectively. The method was applied to determine the plasma concentration of [2H7]KIC after an intravenous administration of [2H7]KIC in rat.

Animals↗

PubMed2001

IM droperidol as premedication attenuates intraoperative hypothermia.

PURPOSE: Perioperative hypothermia results largely from core-to-peripheral heat redistribution. Droperidol, which is often used for premedication, promotes vasodilation, and thus may affect redistribution of heat. Accordingly, we tested the hypothesis that preanesthetic droperidol would affect perioperative hypothermia. METHODS: Twenty-three ASA physical status I patients scheduled for arthroscopic ligament reconstruction were randomly assigned to two groups to receive no premedication or im droperidol 0.1 mg x kg(-1) 30 min before anesthesia. Anesthesia was induced and maintained with propofol and fentanyl. We monitored core (tympanic) and peripheral (palm) temperatures, and skin (fingertip) blood flow for two hours after the induction of anesthesia during surgery. RESULTS: Before the induction of anesthesia, patients given droperidol were more deeply sedated than those given no premedication. Core temperature, which was similar in both groups before induction, decreased significantly more in the control than in the droperidol patients (0.75 +/- 0.34 degrees C and 0.37 +/- 0.20 degrees C, respectively, at 75 min after induction; P <0.01). Preinduction peripheral temperature and skin blood flow were lower in the control group than in the droperidol group, but the two variables became similar in both groups after induction. CONCLUSION: The results of the present study confirm our hypothesis that premedication with droperidol affects perioperative hypothermia. Droperidol may prevent core-to-peripheral heat redistribution after the induction of anesthesia.

Adjuvants, Anesthesia↗

PubMed2001

Changes in NADPH diaphorase expression in the fish visual system during optic nerve regeneration and retinal development.

The various functions of nitric oxide (NO) in the nervous system are not fully understood, including its role in neuronal regeneration. The goldfish can regenerate its optic nerve after transection, making it a useful model for studying central nervous regeneration in response to injury. Therefore, we have studied the pattern of NO expression in the retina and optic tectum after optic nerve transection, using NADPH diaphorase histochemistry. NO synthesis was transiently up-regulated in the ganglion cell bodies, peaking during the period when retinal axons reach the tectum, between 20-45 days after optic nerve transection. Enzyme activity in the tectum was transiently down-regulated and then returned to control levels at 60 days after optic nerve transection, during synaptic refinement. To compare NO expression in the developing and regenerating retina, we have looked at NO expression in the developing zebrafish retina. In the developing zebrafish retina the pattern of staining roughly followed the pattern of development with the inner plexiform layer and horizontal cells having the strongest pattern of staining. These results suggest that NO may be involved in the survival of ganglion cells in the regenerating retina, and that it plays a different role in the developing retina. In the tectum, NO may be involved in synaptic refinement.

Animals↗

PubMed2001

Reactive oxygen species uncouple external horizontal cells in the carp retina and glutathione couples them again.

We have investigated the effect of free radicals on the electrical gap junctions between horizontal cells in the carp retina. In our previous study, L-buthionine sulfoximine, an inhibitor of glutathione synthesis, caused uncoupling of horizontal cells four days after injection. In the present study, we have used paraquat, a generator of exogenous reactive oxygen species, to investigate whether it was the depletion of glutathione or an increase in the level of reactive oxygen species which resulted in horizontal cell uncoupling after L-buthionine sulfoximine injection. Intracellular recordings were made from L-type horizontal cells at various time-points after intravitreal injection of paraquat. Injection of 25nmol paraquat caused an increase in response amplitude to central spot light stimuli by two days after injection, which continued for a further two to three days and had almost disappeared by seven days after injection. There was also a sharp increase in reactive oxygen species production, peaking at four days and disappearing by seven days after injection, and an accompanying depletion and a restoration of glutathione levels with a similar time-course. Marking cells with Lucifer Yellow clearly illustrated uncoupling of horizontal cells after paraquat injection. If paraquat and L-buthionine sulfoximine were injected simultaneously, the increase in response to central spots was observed as early as one day after injection. This response amplitude was not more enhanced than that observed after L-buthionine sulfoximine injection alone, although a dramatic increase in the level of reactive oxygen species was observed. From these results, we suggest that reactive oxygen species are involved in uncoupling, while recovery from uncoupling is dependent on glutathione. Furthermore, we conclude that a balance between glutathione and reactive oxygen species levels is the most important factor controlling gap junctional intercellular communication of L-type horizontal cells in the carp retina.

Animals↗

PubMed2001

A case of awareness with sevoflurane and epidural anesthesia in ovarian tumorectomy.

We experienced a case of awareness during ovarian tumorectomy in a patient who was anesthetized with sevoflurane and epidural anesthesia. A 74-year-old woman was scheduled for resection of an ovarian tumor. After epidural catheter insertion, anesthesia was induced with 60 mg of propofol and 6 mg of vecuronium, and anesthesia was maintained with epidural anesthesia (1% mepivacaine), 1 to 2% sevoflurane, and 66% nitrous oxide in oxygen. The operative course was uneventful and the total operation time was 2 hours and 50 minutes. Two days after the operation, we were surprised to learn that the patient complained of awareness during the surgery.

Aged↗