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Biomedical subjects

H Nagasaka

Publications and source records attributed to H Nagasaka.

At least 37 records · Page 2Linked to original sources
PubMed1997

[The effects of isoflurane on the formalin-induced activity in the spinal dorsal horn of transected cat].

Although the formalin test is widely used in rodents, the electrical response to this stimulus and the effect of isoflurane on this response, has not been well understood in cats. We have therefore examined the effect of isoflurane on spinal wide-dynamic-range neuronal activity evoked by a subcutaneous (s.c.) formalin injection in cats. In decerebrate, spinal cord-transected cats (L 1-2), a s.c. injection of formaldehyde solution (0.05 ml; 5%) was performed in the receptive fields of spinal wide-dynamic-range neurons at the hind paw. Isoflurane (1.5%) inhalation was given 20 mins prior to formalin injection or 5 mins after the formalin injection. The formalin injection elicited an immediate and continuous discharge or burst activity in the neurons that lasted at least 90 min. Inhaled isoflurane was found to markedly inhibit this neuronal discharge. At 30 mins after discontinuing of isoflurane, the neuronal activity in both groups recovered to approximately 55% of the control value. These results suggest that formalin injection will reliably produce a continuous burst of neuronal activity in the spinal dorsal horn of cats, and that this activity can be markedly reduced by isoflurane. The ability of isoflurane to inhibit this neuronal response was not temporally related to the formalin injection.

Administration, Inhalation↗
PubMed1996

Native lipoproteins inhibit platelet activation induced by oxidized lipoproteins.

Copper-catalyzed oxidation of low-density lipoproteins (LDL) (0.8 g protein/l LDL, 20 mumol/l CuSo4, 37 degrees C) resulted in the formation of thiobarbituric reactive substances that was substantially completed at 24 hrs whereas their formation from high-density lipoproteins (HDL) plateaued at only 25% of that amount after 8 hrs. The oxidized lipoproteins induced aggregation and increases in [Ca2+]i in washed platelets, but not in platelet-rich plasma, and these activating effects were not inhibited by aspirin or EGTA but were inhibited by both of the native lipoproteins. These results show that oxidized HDL, like oxidized LDL, have platelet activating ability and suggest that the native lipoproteins may play a crucial role in preventing the oxidized lipoprotein-mediated platelet activation.

Aspirin↗
PubMed1996

Peripheral and spinal actions of opioids in the blockade of the autonomic response evoked by compression of the inflamed knee joint.

BACKGROUND: Three types of opioid receptors, mu, delta, and kappa, are present in the periphery and in the central nervous system. In contrast to the effects in the central nervous system, the antinociceptive action of opioids in the periphery is not as well characterized. The effects of intraarticular, spinal, and intramuscular injections of mu, delta, and kappa opioid agonists on the autonomic response evoked by compression of an inflamed knee joint were evaluated. METHODS: In halothane-anesthetized rats, arthritis was induced by injecting kaolin and carrageenan into the right knee joint. Standardized compression of the knee joint by inflation of a pediatric blood pressure cuff to 200 mmHg for 2 min produced a reliable stimulus-dependent hypertension (delta = 13 mmHg). Drugs were delivered intramuscularly, intrathecally through a chronic catheter, or intraarticularly into the right knee joint. The drug injection was performed 4 hr after induction of the inflammation. RESULTS: The intrathecal administration of mu, delta, and kappa agonists resulted in a dose-dependent blockade of the cuff-evoked increase in blood pressure. The order of intrathecal drug activity on the compression-evoked blood pressure responses with median effective dose (ED50) was sufentanil (0.02 nmol; mu) > PD117302 (0.5 nmol; kappa); spiradoline (1.5 nmol; kappa) morphine (2.4 nmol; mu) > DADL (15 nmol; delta); DPDPE (18 nmol; delta) > U-50,488H (620 nmol; kappa) > naloxone = 0. The intraarticular administration of mu and kappa, but not delta agonists, produced a dose-dependent blockade of a compression-evoked increase in blood pressure, with the order of drug activity (ED40) as follows: sufentanil (0.04 mumol) > PD117302 (0.3 mumol); spiradoline (0.8 mumol), morphine (0.9 mumol) > U-50,488H (0.9 mumol) > DPDPE (> 5 mumol); DADL (> 18 mumol) > naloxone = 0. Intramuscular injection of these agonists caused suppression, with the order of drug activity (ED50) as follows: sufentanil (0.2 mumol) > PD117302 (2 mumol); spiradoline (11 mumol) morphine (9 mumol) > DPDPE (> 5 mumol); DADL (18 mumol) > U-50,488H (22 mumol) > naloxone = 0. All intraarticular effects were reversible by injecting naloxone intramuscularly, with the ordering of naloxone potency against equiactive doses of morphine > U50,488H. CONCLUSIONS: The activity of the respective agonists and the intraarticular > intramuscular ordering of systemic potency in this model indicate that opioids, by an action at mu and kappa, can exert a direct antihyperalgesic action at the terminals of primary afferents projecting to a region of inflammation. These observations offer strong support for a peripheral action of opioids in certain states in inflammation-induced hyperalgesia.

Analgesia↗
PubMed1996

[Pre-emptive analgesia from intravenous administration of opioid: no effect with pentazocine].

The influence of timing of administration of preoperative pentazocine on pain and analgesic requirements after surgery was studied in 46 patients undergoing total abdominal hysterectomy. Twenty-three patients received thiamylal 5 mg.kg-1 on induction of anesthesia, followed by pentazocine 30 mg or 60 mg before surgical incision (group A). Twenty-three control patients received pentazocine 30 mg or 60 mg, 5 min after abdominal incision (group B). The visual analogue scales for pain 24 h after operation were 6.0 cm at 30 mg dose in group A or 5.3 cm at 60 mg dose in group A and 5.7 cm at 30 mg dose in group B or 4.7 cm at 60 mg dose in group B. There were no differences in the visual analogues scales. Pentazocine consumption in the first 24 h after surgery was 67.5 mg at 30 mg dose in group A or 52.5 mg at 60 mg dose in group A and 70.9 mg at 30 mg dose in group B or 51.8 mg at 60 mg dose in group B. We conclude that postoperative pentazocine consumption and pain scores are no different when pentazocine is given before or after skin incision for abdominal hysterectomy and that there is no clinically useful pre-emptive analgesic effect with these doses of pentazocine.

Adult↗
PubMed1995

Effects of intrathecal mu, delta, and kappa agonists on thermally evoked cardiovascular and nociceptive reflexes in halothane-anesthetized rats.

Despite significant opioid binding in the intermediolateral cell column, the effects of intrathecal injections of mu, delta, and kappa opioid agonists on the cardiovascular response to noxious stimulation have not been examined systematically. The pharmacology of intrathecally administered opioid agonists (mu, morphine, [D-Ala2,N-MePhe4,Gly5-ol]enkephalin (DAGO); delta, metkephamid, [D-Ala2-D-Leu5]enkephalin (DADL), [D-Pen2,D-Pen5]enkephalin (DPDPE); kappa, U50488H and PD117,302) or agonist-antagonist (nalbuphine) on somatomotor (tail-flick) and cardiovascular changes (blood pressure and heart rate) evoked by immersing the tail in 53 degrees C water were examined in rats anesthetized with halothane (0.75%) and in which intrathecal catheters had been chronically implanted. Intrathecal administration of mu and delta, but not kappa agonists or agonist-antagonist produced a dose-dependent block of tail-flick and evoked cardiovascular responses with the order of activity being as follows: DAGO > metkephamid DADL > morphine > DPDPE >> nalbuphine = PD117,302 = U50488H = 0. These effects were reversed readily by the opioid antagonist naloxone. In addition, intrathecal administration of mu and delta but not kappa or agonist-antagonist had little effect on resting heart rate and blood pressure. These data indicate that the agonist occupancy of spinal mu and delta, but not kappa agonists can profoundly modulate the autonomic and somatomotor response evoked by high threshold thermal stimuli.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1995

[Halothane reduces the inhibition of dorsal horn lamina V type neuronal activity induced by bradykinin injection into the femoral artery contralateral to the recording site].

Effect of halothane (0.2%, 0.5%, and 1.0%) on spinal function were studied in lamina V type cells responding to noxious and light touch applied at their cutaneous receptive field on the foot pad of the left hind paw. Extracellular unit activities of lamina V type cells were recorded at the lumbar level in six cats and thirteen spinal cats. When intra-arterial injection of bradykinin (BK) 10 micrograms into the femoral artery ipsilateral to the recording sites was used as the noxious test stimuli, six of these cells (100%) were found to have inhibitory response in six intact cats and thirteen of these cells (100%) were found to have excitatory response in thirteen spinal cats. On the other hand, when the injection of 10 micrograms into the femoral artery contralateral to the recording sites was used as the noxious test stimuli, six of these cells (100%) were found to have inhibitory response in six intact cats and six of these cells (46%) were found to have inhibitory response in thirteen spinal cats. We studied the effect of halothane on the inhibition induced by BK injection into the femoral artery contralateral to the recording sites in six intact cats and six spinal cats. Halothane 0.2%, 0.5% and 1.0% reduced the inhibition of dorsal horn lamina V type neuronal activity induced by BK injection.

Animals↗
PubMed1995

Surgical-orthodontic treatment in Class II, division 2, malocclusion: a case report involving pretreatment and posttreatment evaluation of temporomandibular dysfunction.

The case of a patient who had a significant Class II, division 2, malocclusion and experienced myofascial pain dysfunction is presented. The patient was a 22-year-old Japanese woman who complained of pain and fatigue in her masticatory muscles. During presurgical orthodontic treatment, a one-tooth osteotomy was utilized to correct the lingual inclination of an ankylosed maxillary central incisor. The surgery consisted of intrusion of the anterior segment of the maxilla, intrusion of the anterior segment of the mandible, mandibular advancement by sagittal split ramus osteotomy, and trimming of the gonial angles. Postoperatively, her facial appearance and occlusion were good. Furthermore, the function of the temporomandibular joints was improved and the symptoms of myofascial pain and dysfunction disappeared.

Adult↗
PubMed1994

[Effect of isoflurane on spinal dorsal horn WDR neuronal activity in cats].

The effects of isoflurane (0.5% and 1.5%) on the spinal dorsal horn wide dynamic range (WDR) neuronal activity were studied in either spinal cord intact or spinal cord-transected cats. Extracellular activity was recorded in the dorsal horn from single WDR neurons responding to noxious and non-noxious stimuli applied to the cutaneous receptive fields on the left hind foot pads of intact or decerebrate, spinal cord transected (L1-2) cats. When bradykinin (BK) 10 micrograms was injected into the femoral artery ipsilateral to the recording site as the noxious test stimulus in the spinal cat, all of 17 WDR neurons gave excitatory responses which were not depressed by 0.5% isoflurane but were depressed significantly by 1.5%. On the other hand, when the injection of BK 10 micrograms into the femoral artery ipsilateral to the recording site was used in the intact cat, 13 of 24 WDR neurons (54%) gave excitatory responses, which were significantly depressed by 0.5% and 1.5% isoflurane, and 11 of 24 WDR neurons (46%) gave inhibitory responses, which were significantly depressed by 0.5% and 1.5% isoflurane. We have found that isoflurane reduces the excitation as well as the inhibition of dorsal horn WDR neuronal activity induced by BK injection.

Action Potentials↗
PubMed1993

The effects of ketamine on the excitation and inhibition of dorsal horn WDR neuronal activity induced by bradykinin injection into the femoral artery in cats after spinal cord transection.

BACKGROUND: It is now well established that wide dynamic range neurons (WDR) can possess widespread cutaneous inhibitory receptive fields, as well as excitatory receptive fields, in specific regions of the body. The ability of ketamine to depress the excitatory responses of spinal WDR neurons indicates that the analgesia produced by this agent may be a result, in part, of this spinal action. The primary purpose of this study was to investigate the effects of ketamine on the WDR propriospinal inhibitory mechanism that is induced by a bradykinin (BK) injection as a noxious test stimuli. METHODS: In decerebrate, spinal cord-transected cats (L1-L2), the effects of a low (0.5 mg.kg-1, intravenous) and a high (10 mg.kg-1, intravenous) dose of ketamine on the neuronal activity of spinal dorsal horn WDR neurons evoked by femoral artery injection of BK (10 micrograms) was examined. Extracellular activity was recorded from single WDR neurons that responded to noxious and innocuous stimuli applied to the cutaneous receptive fields on the foot pads of the left hind paw. RESULTS: After ipsilateral BK administration, the activity of the WDR neurons was found to be increased (excited) in all ten neurons that were examined. In contrast, the activity of these neurons was found to be decreased (inhibited) in five of these ten neurons after BK administration into the contralateral femoral artery. The 10 mg.kg-1 dose of ketamine significantly suppressed the excitatory activity observed in all 15 of the WDR neurons examined. A comparison of the effects produced by the 0.5-mg.kg-1 and the 10-mg.kg-1 intravenous doses reveals that the amount of suppression was dose-related. In addition, the inhibitory WDR neuronal activity induced by contralateral BK injection was also significantly reduced by both the 0.5- and the 10-mg.kg-1 doses of ketamine. CONCLUSIONS: These results indicate that this reduction of excitatory and inhibitory responses of WDR neurons after noxious stimulation is likely to be the fundamental basis for the spinal cord component of ketamine-induced analgesia.

Animals↗
PubMed1993

[Effects of sevoflurane on spinal dorsal horn WDR neuronal activity in cats].

The effects of sevoflurane (S) (0.5%, 1.5%, and 2.5%) on the spinal dorsal horn wide dynamic range (WDR) neuronal activity were studied in either spinal cord intact or spinal cord transected cats. Extracellular activity was recorded in the dorsal horn from single WDR neurons responding to noxious and non-noxious stimuli applied to the cutaneous receptive fields on the left hind paw foot pads of intact or decerebrate and spinal cord transsected (L1-2) cats. When BK 10 micrograms was injected into the femoral artery ipsilateral to the recording site as the noxious test stimulus in the spinal cat, 7 of 8 WDR neurons gave excitatory responses which were not depressed by sevoflurane 0.5% and 1.5% but were depressed significantly by 2.5%. On the other hand, when BK 10 micrograms was injected into the femoral artery ipsilateral to the recording site in the intact cat, 6 of 13 WDR neurons (46%) gave excitatory responses, which were significantly depressed by sevoflurane 0.5%, 1.5% and 2.5%, and 7 of 13 WDR neurons (54%) gave inhibitory responses, which were significantly depressed sevoflurane at 0.5%, 1.5%, and 2.5%. In conclusion, we have found that sevoflurane reduces the excitation as well as the inhibition of dorsal horn WDR neuronal activity induced by BK injection.

Animals↗
PubMed1992

[Effects of age on blood pressure, heart rate, and sensory blockade by spinal anesthesia with plain 0.5% bupivacaine].

To discover the influence of age on spinal blockade with plain bupivacaine, 23 patients were administered a subarachnoid injection of approximately 4.0 ml of 0.5% bupivacaine. The patients were divided into two groups. One group consists of patients with ages under 65 years (younger group, n = 13), and the other group consists of patients older than 65 years (elder group, n = 10). The following results were obtained. The time to onset of anesthetic effects (pinprick discrimination, temperature discrimination, and light touch discrimination) decreased with age. At 180 min after the administration, spinal blockade level did not have a significant difference. The degree of the decrease of systolic arterial pressure was greater in the elder group than in the younger group. However, the degree of the decrease of heart rate was greater in the elder group than in the younger group.

Adolescent↗
PubMed1992

[The determination of basic fibroblast growth factor (bFGF) in human placental tissue and the changes in bFGF during pregnancy].

The purpose of this study is to develop an assay system for quantification of bFGF in human tissue and to investigate the changes in bFGF content in the human placenta during pregnancy. Sixty-two placental tissue samples from various stages of normal pregnancies were collected. Approximately 28 micrograms bFGF was obtained per 1 kg of placental tissue. The recovery rates were 17.1 +/- 7.4%. The purified samples were confirmed as bFGF by SDS-PAGE and enzyme-linked immunoelectrotransfer blot (EITB) with anti-human bFGF monoclonal antibody. The bFGF readings in the human placenta determined by RIA were 11.81 +/- 2.11 fmol/mg protein (first trimester), 20.45 +/- 4.85 (early second trimester), 9.52 +/- 5.02 (late second trimester), 7.41 +/- 2.07 (third trimester), and 7.75 +/- 1.86 (post trimester). The placental bFGF were significantly high in the early stage of second trimester and declined gradually during the remainder of the pregnancy. The RIA values were correlated closely with the values obtained by bioassay. These results demonstrate that our assay system provides a tool for the quantification of bFGF in biological samples and suggest that bFGF, the active mitogen and angiogenic factor, participates in the formation of the human placenta.

Angiogenesis Inducing Agents↗
PubMed1991

[Effects of halothane on spinal dorsal horn WDR(wide dynamic range) neuronal activity in cats].

The effects of halothane (0.2%, 0.5%, and 1.0%) on the spinal dorsal horn wide dynamic range (WDR) neuronal activity was studied in either spinal cord intact or spinal transected cats. Extracellular activity was recorded in the dorsal horn from single WDR neurons responding to noxious and non-noxious stimuli applied to the cutaneous receptive fields on the left hind foot pads of intact or decerebrate, spinal cord transected (L 1-2) cats. When 10 micrograms of bradykinin was injected into the femoral artery ipsilateral to the recording site as the noxious test stimulus in the spinal cat, all of 7 WDR neurons gave excitatory responses which were not depressed by 0.2% and 0.5% halothane but were depressed significantly by 1.0%. On the other hand, when the injection of 10 micrograms of bradykinin into the femoral artery ipsilateral to the recording site was used in the intact cat, 7 of 14 WDR neurons (50%) gave excitatory responses, which were not depressed by 0.2% halothane but were significantly depressed by 0.5% and 1.0% halothane, and 7 of 14 WDR neurons (50%) gave inhibitory responses, which were significantly depressed by 0.2%, 0.5%, and 1.0% halothane. We have found that halothane reduces the excitation as well as the inhibition of dorsal horn WDR neuronal activity induced by bradykinin injection.

Animals↗
PubMed1990

Enflurane reduces the excitation and inhibition of dorsal horn WDR neuronal activity induced by BK injection in spinal cats.

The effects of enflurane (0.5%, 1.5% and 2.5%) on the excitation and inhibition of dorsal horn wide dynamic range (WDR) neuronal activity induced by bradykinin (BK) injection was studied in spinal cats. Extracellular activity was recorded in the dorsal horn from single WDR neurons responding to noxious and non-noxious stimuli applied to the cutaneous receptive fields on the left hind paw foot pads of decerebrate, spinal cord transected (L(1-2)) cats. When 10 microg of BK was injected into the femoral artery ipsilateral to the recording site as the noxious test stimulus, 24 of 26 WDR neurons (92%) gave excitatory responses and 2 (8%) gave inhibitory responses. On the other hand, when the injection of 10 microg of BK into the femoral artery contralateral to the recording site was used as the noxious test stimulus, 7 of 12 WDR neurons (58%) gave inhibitory responses, 3 (25%) gave excitatory responses, and 2 (17%) showed no response. The excitatory neuronal activity in WDR neurons was not depressed by 0.5% or 1.5% enflurane but was depressed significantly by 2.5%. However, the inhibitory neuronal activity in WDR neurons was significantly depressed by 0.5%, 1.5% and 2.5% enflurane. We have found that enflurane reduces the excitation as well as the inhibition of dorsal horn WDR neuronal activity induced by BK injection. These results suggest that the reduction of excitatory and inhibitory responses produced by noxious stimulation is likely to be the fundamental basis of the enflurane-induced anesthetic state in terms of WDR neurons.

Journal Article↗
PubMed1990

Pharmacology of intrathecal adrenergic agonists: cardiovascular and nociceptive reflexes in halothane-anesthetized rats.

The effects of intrathecally administered adrenergic agonists (alpha-1-methoxamine, alpha-2-dexmedetomidine, clonidine, and ST-91, beta-isoproterenol) on nociceptive (tail-flick reflex) and cardiovascular changes (blood pressure and heart rate) evoked by immersing the tail in 53 degrees C water were examined in rats anesthetized with halothane (0.75%) and in which intrathecal catheters had been chronically implanted. Administration of intrathecal alpha-2, but not alpha-1 or beta agonists, produced a dose-dependent block of the tail-flick and evoked cardiovascular responses with the order of activity being as follows: dexmedetomidine greater than clonidine greater than ST-91 much greater than methoxamine greater than or equal to isoproterenol. These effects were readily reversed by the alpha-2 antagonist idazoxan. Intravenously administered dexmedetomidine at a dose that is active when given intrathecally (0.33 micrograms) was without effect on either the tail-flick or the evoked cardiovascular responses. Without drugs, the halothane MAC was 1.23 +/- 0.07%. In the presence of intrathecally administered dexmedetomidine (0.33 micrograms), the MAC was significantly reduced to 0.9 +/- 0.09%. The intrathecal administration of alpha-2 agonists resulted in a rapid decrease in resting blood pressure and heart rate with the magnitude of hypotension being as follows: dexmedetomidine greater than clonidine greater than ST-91. These data suggest a potent spinal alpha-2-receptor-mediated modulation of somatomotor and autonomic responses to pain.

Adrenergic Agonists↗