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Biomedical subjects

Y Ikuta

Publications and source records attributed to Y Ikuta.

At least 73 records · Page 4Linked to original sources
PubMed1999

Rejection and regeneration in peripheral nerve homografts in rats after withdrawal of cyclosporin: morphological and immunohistochemical assessment.

Peripheral nerve homografts 35 mm long were inserted in rats to study rejection and regeneration of nerves after suspension of an immunosuppressant (cyclosporin), and the correlation between the Schwann cells of the host and the donor during the course of regeneration. Sciatic nerve homografts from 36 ACI-RT1a rats were transplanted into Lewis-RT1(1) rats. Isografts were taken from 24 Lewis rats. Cyclosporin 5 mg/kg/day was given subcutaneously for 12 weeks. In the homograft group the myelinated axons that regenerated while the immunosuppressant was being given were covered mainly with Schwann cells from the donor, and after the immunosuppressant was withdrawn both Schwann cells of the donor and axons were rejected. However, while the cyclosporin was being given the Schwann cells of the host migrated into the nerve graft together with a few myelinated axons that escaped rejection, and unmyelinated axons that regenerated after rejection were myelinated by the Schwann cells of host.

Animals↗
PubMed1999

Anterior laxity and MR signals of the knee after exercise. A comparison of 9 normal knees and 6 anterior cruciate ligament reconstructed knees.

9 healthy volunteers and 6 patients with anterior cruciate ligament (ACL) grafts underwent anterior knee laxity measurements and MRI examinations of their knees before and after intensive physical exercise. In the volunteer group, anterior displacement of the knee at 89 and 133 newtons of loading, measured with a KT-2000 knee arthrometer, increased after exercise, compared to before it. In addition, anterior terminal stiffness decreased at 133 newtons of anterior loading. In the ACL group, anterior displacement at 89 and 133 newtons of loading also increased, while no difference was found in anterior terminal stiffness before versus after exercise. On MRI, the signal intensity of normal ACLs after exercise was higher than before it. In contrast, the signals from the grafts showed no differences before versus after exercise. Our findings suggest that the ACL grafts are biomechanically and biochemically different from normal ACLs, even 15 months after ACL reconstruction.

Adolescent↗
PubMed1999

Bone marrow-derived dendritic cells incorporate and process hydrophobized polysaccharide/oncoprotein complex as antigen presenting cells.

We have previously shown that a novel hydrophobized polysaccharide/oncoprotein complex vaccine can induce immune responses against the HER2/neu/c-erbB2 (HER2) expressing tumors. Bone marrow-derived dendritic cells (DCs), as antigen presenting cells (APCs), are the first candidates for presentation of tumor antigens. The aim of this study was to see whether DCs are able to elicit antigen specific host immune responses by stimulating the proliferation of T cells after exposure to cholesteryl group bearing pullulan (CHP) and HER2 protein complex. Vaccination by CHP-HER2 complex was as effective as cholesteryl group bearing mannan (CHM) and HER2 complex on which we reported previously. Immunization of mice with HER2 expressing CMS17HE tumor cells generated both CD4+ T cells and CD8+ T cells reactive with CHP-HER2 complex pretreated DCs. In addition, immunization with either CHP-HER2 complex or HER2 protein alone could also generate both CD4+ T cells and CD8+ T cells specifically reactive with CHP-HER2 complex pretreated DCs. The complete rejection of tumors occurred when immunization with CHP-HER2 complex pretreated DCs was started 10 days after tumor inoculation. Therefore, bone marrow-derived DCs pretreated with hydrophobized polysaccharide/oncoprotein complex are a powerful tool for enhancing the effectiveness of oncoprotein for anti-tumor vaccination, opening new options for immune cell therapy.

Animals↗
PubMed1998

Magnitude of skin vasomotor reflex represents the intensity of nociception under general anesthesia.

Because nociceptive stimuli induce the skin vasomotor reflex (SVmR), the assessment of the SVmR would be a useful indicator to represent nociception. We examined 39 adult patients for the relationship between the magnitude of the SVmR and the intensity of nociceptive stimulus that induced the SVmR. Under oxygen-nitrous oxide (50%) and sevoflurane anesthesia, the SVmR was induced by an electrical impulse to the ulnar nerve and detected by a laser Doppler flowmeter. Study 1: under the end-tidal concentrations of sevoflurane at 1.2% (n = 10), 1.7% (n = 9) or 2.2% (n = 10), the SVmR was tested by a 2-s, 50-Hz tetanic electrical impulse with a current intensity changing (40, 50 or 60 mA) in a randomized order. Study 2: under the end-tidal concentration of sevoflurane at 1.7% (n = 10), the SVmR testing was performed with a 50-mA, 50-Hz tetanic electrical impulse with the current duration changing (2, 3 or 4 s) in a randomized order. The studies demonstrated significant correlations of (1) the current intensity which induces the skin vasomotor reflex (SVmR) vs. the magnitude of the SVmR under the three different anesthesia depths, (2) the anesthesia depth vs. the magnitude of the SVmR (inverse proportion) under the same current intensity and (3) the duration of electrostimulation vs. the magnitude of the SVmR. Thus, the SVmR could be helpful for the objective assessment of nociception and anti-nociceptive effects in individual cases.

Adult↗
PubMed1998

Lipoma arborescens in bilateral knee joints.

We report a case of lipoma arborescens of both knee joints. In the face of chronic joint hydrops, it is important to consider lipoma arborescens in the differential diagnosis and to try to make early diagnosis, using magnetic resonance imaging or another means of examination.

Adult↗
PubMed1998

Adverse effects on rabbit anterior cruciate ligament after knee immobilization: changes in permeability of horseradish peroxidase.

Changes in the permeability of horseradish peroxidase (HRP) and the histology of the rabbit anterior cruciate ligament (ACL) caused by knee immobilization were studied. The knees of adult rabbits were immobilized for 2-8 weeks by a long leg cast with the knee flexed at 120 degrees, and some joints were allowed to be remobilized for 4 weeks after 6 or 8 weeks' immobilization. After 1 ml of HRP was injected into the knee joint and allowed to permeate into the ACL, the degree of permeation at the mid-portion of the ACL between femur and tibia was visualized with diaminobenzidine tetrahydrochloride. The ACL was examined histologically by light and transmission electron microscopy. Although the HRP permeated into almost the entire area of the transverse section of the non-immobilized normal ACL, as the period of immobilization increased, the extent of permeation gradually decreased. The decrease was significant from week 4 to week 6 and from week 6 to week 8. Degenerative change with necrosis of cells at the central area of the ACL was noted in the 6-week immobilization group, and the 8-week period of immobilization increased the extent of this degeneration. Although the permeation recovered in both the 6-week and 8-week immobilization groups 4 weeks after remobilization, there were fewer cells with a normal morphology in the central area in the 8-week immobilization group than in the control. These results suggest that long-term immobilization adversely affects the ACL.

Analysis of Variance↗
PubMed1998

Antinociceptive effects of neurotropin in a rat model of painful peripheral mononeuropathy.

A non-protein extract isolated from the inflamed skin of rabbits inoculated with vaccinia virus (Neurotropin, NTP), has been clinically used in Japan for the treatment of chronic painful conditions such as low back pain, osteoarthritis, postherpetic neuralgia, subacute myelo-opticoneuropathy, and so on. Recent studies have shown its efficacy on patients with complex regional pain syndrome (CRPS). The chronic constriction injury (CCI) model described by Bennett and Xie has been thought to show similar painful conditions to those seen in CRPS patients. Thus, the antinociceptive effects of NTP were tested in CCI model. In rats with mechanical hyperalgesia 2 weeks after nerve injury, i.p. injection of NTP (100 Neurotropin Unit, NU/kg) produced an analgesic effect that lasted for at least 50 min. An analgesic effect lasting up to 30 min. was observed in rats with heat hyperalgesia 2 weeks after nerve injury. Seven daily i.p. injections (50 NU/kg) of NTP commencing 1 week after surgery produced an early recovery from heat hyperalgesia. Prior studies suggest that NTP produces analgesia by activation of a descending pain inhibitory system. Thus, our findings suggest the possibility that the dysfunction of the descending pain inhibitory system could be related to the hyperalgesia in the nerve injury model, and perhaps also in people who suffer from painful peripheral neuropathies.

Analgesics↗
PubMed1998

Effects of neurotropin on hyperalgesia and allodynia in mononeuropathic rats.

Neurotropin is commonly used in Japan for the treatment of chronic pain. Using a rat model, we evaluated the effect of neurotropin on a unilateral peripheral mononeuropathy produced by placing loose ligatures around the sciatic nerve. The effect of neurotropin upon the resultant hyperalgesia and mechanical allodynia was assessed using the Ugo Basile Plantar test and von Frey hairs test, respectively. Neurotropin reduced thermal hyperalgesia and produced an early recovery from hyperalgesia in a dose-dependent manner. No significant reduction in mechanical allodynia, however, was noted under the tested condition. A possibility of differential drug sensitivity for thermal hyperalgesia and mechanical allodynia was indicated in this model, although the reason still remain elusive.

Analgesics↗
PubMed1998

Results of treatment of chronic dorsal fracture-dislocations of the proximal interphalangeal joints of the fingers.

We reviewed 20 cases of chronic dorsal fracture-dislocation of the proximal interphalangeal joint, with a mean follow-up period of 74 months. In patients without comminuted palmar fragments, open reduction and internal fixation or osteotomy of the malunited fragment provided good results. In treating patients with damaged articular cartilage or with comminuted palmar fragments by palmar plate arthroplasty, poor results were obtained because of secondary osteoarthritic changes.

Adolescent↗
PubMed1998

Increase of nerve regeneration capacity by new neurotrophic pyrimidine derivative MS-430.

1. We studied whether a new neurotrophic pyrimidine compound, MS-430, can increase the regeneration length of the transected sciatic nerve in a silicone chamber gap of 14 mm. 2. The average length of regenerated myelinated axons in ten cases was 9.0+/-0 mm in the control group, 2.8+/-1.9 mm in the 1 mg/kg/day of the MS-430 group and 5.0+/-5.1 mm in the 3 mg/kg/day of the MS-430 group, indicating that the average length was significantly larger in the 3-mg group than that in the control group (P<0.05). 3. The results clearly showed that the MS-430 has promoting effects on nerve regeneration.

Animals↗
PubMed1998

Quantitative evaluation of nutritional pathways for the posterior cruciate ligament and the lateral collateral ligament in rabbits.

The cruciate ligament of the knee receives its nutrition from a direct vascular supply and by permeation of nutrients from the synovial fluid. The contributions of these two routes as nutritional pathways are not known in detail. In this study, we injected [3H]methyl glucose as a tracer intravenously or directly into the knee of rabbits. Tracer concentrations in plasma, synovial fluid, the posterior cruciate ligament (PCL), and the lateral collateral ligament (LCL) were analysed by a pharmacokinetic compartment model. The contribution of [3H]methyl glucose permeation from the synovial fluid during steady state was calculated at 44.3% in the PCL and at 39.0% in the LCL. Although these results indicated that more than half the nutrition for both ligaments is provided by its vascular supply, synovial fluid permeation is also an important transport route for small molecules for the PCL and the LCL, which is an extra-articular structure.

Animals↗
PubMed1998

Skin vasomotor reflex as an objective indicator to assess the level of regional anesthesia.

UNLABELLED: We examined whether the absence of a skin vasomotor reflex (SVmR), which represents a sympathetic vasoconstrictive response to various stimuli, is an objective indicator of a somatosensory blockade. Skin blood flow was measured by using a laser Doppler flowmeter on the index finger tip. The somatosensory blockade level was determined in 15 patients under subarachnoid anesthesia. A cold stimulus, an ice cube applied to the skin, was repeated sequentially at each dermatome from L3 cephalad. The uppermost dermatome with negative response (the SVmR cold level) was determined, and the SVmR pain level was determined similarly using an electrical impulse (20-mA, 50-Hz, 0.25-ms square wave). The SVmR cold level and the SVmR pain level showed significant correlation with the conventionally assessed cold level (r = 0.83) and the pinprick level (r = 0.96). We conclude that the SVmR is useful to objectively estimate the level of somatosensory block induced by regional anesthesia. IMPLICATIONS: We evaluated the absence of decrease in skin blood flow after various stimuli as an indicator of somatosensory blockade. In patients under subarachnoid anesthesia, the uppermost level with negative response showed significant correlation with the conventionally assessed blockade level. This method is useful for objective assessment of regional anesthesia level.

Adult↗
PubMed1998

Assessing the level of regional blockade under general anesthesia using the skin vasomotor reflex test.

UNLABELLED: We investigated whether skin vasomotor reflex (SVmR) testing can be used to assess the sensory blockade level under light general anesthesia. In 15 patients scheduled for abdominal gynecological surgery, the SVmR was tested under inhaled isoflurane or sevoflurane (0.5%-0.6%) with nitrous oxide (50%). Seven minutes after the epidural injection (5-10 mL of 2% lidocaine), a tetanic electrical stimulus (20 mA, 2 s) was applied to the skin and repeated sequentially from the L3 dermatome in the cephalad direction. Changes in the laser Doppler skin blood flow on the index finger tip were assessed for the SVmR. If there was a positive response, SVmR testing was discontinued. The relationship between the uppermost dermatome of the negative SVmR response and the intraoperative effectiveness of the epidural block was determined. In 11 patients, we confirmed a clear boundary of skin dermatome by the SVmR test. The uppermost dermatome of the negative SVmR response at higher than the T7 level was necessary to maintain the combined epidural and light general anesthesia for the transabdominal gynecological surgery (P = 0.002). We conclude that SVmR testing is useful in estimating the blockade level of regional anesthesia under light general anesthesia. IMPLICATIONS: Considering "preemptive analgesia," a complete sensory blockade should be established before a skin incision. In 11 of 15 patients under epidural/ general anesthesia, we confirmed a clear dermatome boundary using the skin vasomotor reflex test. This test could be an indicator for estimating the sensory blockade level of patients under general anesthesia.

Abdomen↗
PubMed1998

Skin vasomotor reflex predicts circulatory responses to laryngoscopy and intubation.

BACKGROUND: An evaluation of autonomic reactivity may help to predict circulatory responses to intubation. The relation between the magnitude of the skin vasomotor reflex (SVmR) immediately before laryngoscopy and the circulatory responses to intubation was examined. METHODS: Forty-four adult patients (classified as American Society of Anesthesiologists physical status I or II) were studied. General anesthesia was induced with fentanyl and thiamylal and maintained with nitrous oxide and sevoflurane. The SVmR was evoked by an electrostimulus to the ulnar nerve, and decreases in skin blood flow were detected using a laser-Doppler flowmeter. In study 1, two groups of patients were studied. In the monitored group (n = 14), laryngoscopy was performed when the SVmR amplitude had decreased to less than 0.1. In the control group (n = 15), intubation was performed regardless of changes in the SVmR amplitude. In study 2, after induction, the end-tidal concentration of sevoflurane was maintained at 1 MAC (n = 9) or 1.3 MAC (n = 6) for 5 min. The SVmR was tested by changing the electric intensity. RESULTS: In study 1, the blood pressure and heart rate of the control group increased significantly (P < 0.01) after laryngoscopy. The blood pressure of the monitored group did not increase. The SVmR amplitude and the systolic blood pressure changes showed a significant linear correlation (P < 0.001). In study 2, the relation between the electric intensity and the SVmR amplitude showed a weak but significant correlation (P < 0.01) in the 1 MAC group. CONCLUSION: The evaluation of the SVmR provides useful information for determining the optimal anesthetic depth for laryngoscopy and intubation in individual patients.

Adult↗
PubMed1998

Long-term results of surgical treatment for macrodactyly of the hand.

A retrospective review was performed for 23 patients who were surgically treated for macrodactyly of the hand between 1964 and 1995. Treatment regimens varied among the patients, and more than two operative procedures were performed in 65 percent of the patients. At final follow-up, the average length of the affected digits was 102 percent of that of the normal contralateral side. The average circumference of the digits was 121 and 124 percent at the proximal interphalangeal and distal interphalangeal joints, respectively. The average range of motion was 65, 57, and 37 degrees at the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints, respectively. Although it is difficult to compare treatment regimens, epiphysiodesis/epiphysectomy was quite effective in the prevention of longitudinal overgrowth of the digits, but resection of the hypertrophic nerves was unsuccessful in preventing finger overgrowth.

Female↗