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Biomedical subjects

K Kaneko

Publications and source records attributed to K Kaneko.

At least 253 records · Page 14Linked to original sources
PubMed1998

Effect of the mono- and tetra-sialogangliosides, GM1 and GQ1b, on long-term potentiation in the CA1 hippocampal neurons of the guinea pig.

Effects of the mono- and tetra-sialogangliosides, GM1 and GQ1b, on long-term potentiation (LTP) were investigated in the CA1 neurons of guinea-pig hippocampal slices. The magnitude of LTP induced by a strong tetanus (100 Hz, 100 pulses) was not significantly affected by application of either ganglioside. In contrast, when LTP was induced by a weak tetanus (100 Hz, 4 pulses), a significantly greater LTP was induced in the presence of either ganglioside. Similarly, when slices were incubated in low-Ca2+ (1.0-1.1 mM) medium for more than 2 h, the LTP was usually small or absent, but showed a significant increase in amplitude of population spike (A-PS) when the slices were incubated with either GM1 or GQ1b (4-5 microg/ml). In addition, the application of GQ1b (4 microg/ml) reversed the blocking effect of an NMDA-receptor antagonist, APP-5 (10 microM), on the induction of LTP and resulted in forming LTP. Based on these findings, we conclude that GM1 and GQ1b exert positive modulatory effects on the induction of LTP in hippocampal CA1 neurons and suggest that GM1 and GQ1b may participate in the induction of LTP as donors of Ca2+ ions.

Animals↗
PubMed1998

Roles of macrophages in programmed cell death and remodeling of tail and body muscle of Xenopus laevis during metamorphosis.

Examination was made of the involvement of macrophage phagocytosis in programmed cell death of tail and body muscle of the frog, Xenopus laevis, during metamorphosis by electron microscopy and immunohistochemical analysis. Electron microscopic observation revealed that macrophages were often found to be present in body and tail muscles at the most active stage of metamorphosis and to actively phagocytose apoptotic muscle fragments. Developmental changes in macrophages were examined using the macrophage-specific antibody, HAM56. Macrophages initially appeared in the early climax stage (stage 59), when the triiodothyronine (T3) level was high, increased rapidly during the process of muscle cell death, and assumed their greatest number at the late climax stage (stage 63/64). They decreased after stage 65/66, with a decrease in T3. Distribution and change in the number of macrophages were the same as those of muscle apoptotic bodies (sarcolytes) during metamorphosis, which suggests an interactive mechanism between macrophages and dying muscle cells. For clarification of this, study was made of the expression of HAM56 antigens that were X. laevis homologs of mouse attachmin, non-specific adhesion proteins in macrophages. The expression of HAM56 antigens in macrophages was found to increase with macrophage phagocytosis at the late climax stage, thus, macrophage differentiation would appear to take place during metamorphosis and HAM56 antigens may be essential for macrophage-dying muscle cell interactions.

Animals↗
PubMed1998

Changes in high K+-evoked serotonin release and serotonin 2A/2C receptor binding in the frontal cortex of rats with thioacetamide-induced hepatic encephalopathy.

Serotonergic systems were investigated in the frontal cortex of rats with thioacetamide (TAA)-induced acute hepatic encephalopathy (HE). Extracellular basal levels of 5-HT showed no difference between control and HE animals, whereas the levels of 5-HIAA were significantly increased in HE rats. Unlike basal levels, high K+-evoked 5-HT release was significantly higher in HE rats than controls. Bmax of (+/-)-1-(2,5-dimethoxy-4-[125I] iodophenyl)-2-aminopropane ([125I] DOI) binding, mainly labeling postsynaptic 5-HT2A receptors, was significantly decreased without any change in Kd in HE rats. These results suggest that there is no change in basal 5-HT release in the cortex of rats with TAA-induced HE despite the increase in intraneuronal 5-HT metabolism and in the size of releasable 5-HT pool, and that serotonergic neurotransmission via 5-HT2A receptor is altered in the brain area of rats with HE.

Acute Disease↗
PubMed1998

Extrinsic nerve strands in the aganglionic segment of Hirschsprung's disease.

BACKGROUND/PURPOSE: The distributions and pathways of the extrinsic enteric nerves in the aganglionic segment in Hirschsprung's disease (HD) have not been delineated completely. The authors have clarified the major pathways and the details of fine distribution of the extrinsic nerves in the aganglionic segment of a congenital aganglionosis rat. Further investigation was extended to apply those findings in human materials. METHODS: Five HD patients, eight fetuses, and two postmortem neonates with normally innervated colon were examined. Specimens were observed by histochemical technique using light microscopy in whole-mount preparations. RESULTS: Two sets of extrinsic nerve strands were observed in the distal aganglionic colon; one consisted of a continuous network located between the longitudinal and circular muscle coats, and the other involved branches that mainly coursed along the blood vessels in the submucosal layer originating from the nearby mesentery. These two sets of nerve strands were similar to those of aganglionosis rats. Also, thick nerve strands were found running longitudinally in the myenteric layer in the normally ganglionated colon of 18- and 21-week-old fetuses. These nerve strands were unclear in a 32-week-old fetus. CONCLUSIONS: This study showed the following: (1) the origin of the nerve strands in the myenteric layer is mainly the pelvic nerve plexus and (2) the number of ascending extrinsic nerve strands decreases from the proximal colon in cases of long-segment aganglionosis, which may be caused by the same process that occurs in the normally innervated bowel.

Colon↗
PubMed1998

Surgical removal of protein plugs complicating choledochal cysts: primary repair after adequate opening of the pancreatic duct.

BACKGROUND/PURPOSE: Recently, pancreaticoduodenectomies have been performed for choledochal cysts complicated by protein plugs. The authors describe a new surgical procedure for removal of protein plugs or pancreatic stones that does not involve pancreatectomy. METHODS: Protein plugs were detected in 43 (34.1%) of 126 pediatric patients with choledochal cysts. The plugs disappeared spontaneously in 26 patients and were removed using nonsurgical methods in seven. The 10 patients treated surgically are considered here. RESULTS: Protein plugs were removed with the residual cyst in one patient. The plugs in the common channel were flushed into the duodenum by irrigation with saline through the narrow segment beneath choledochal cyst in another. The plugs were removed through the narrow segment using a blunt spoon in four. In the other four patients, the plugs that were too large or too hard to be removed through the narrow segment were taken away through an incision in the main pancreatic duct. This was followed by primary closure of the main pancreatic duct using the narrow segment as a flap to prevent stricture formation. All of the patients have done well. CONCLUSIONS: Protein plugs complicating choledochal cysts can be removed without pancreatectomy. Particularly, primary repair of the pancreatic duct using a flap made of the narrow segment beneath the choledochal cyst is a safe and feasible method to remove large or hard protein plugs.

Adolescent↗
PubMed1998

Combined resection of abdominal aorta and inferior vena cava for retroperitoneal rhabdomyosarcoma invading the aortoiliac bifurcation.

The authors report on an 11-year-old boy with retroperitoneal alveolar rhabdomyosarcoma at the aortoiliac bifurcation. The tumor was resected en bloc together with the infrarenal abdominal aorta and the inferior vena cava. The aortic defect was repaired successfully with a Y-shaped Dacron graft. The authors conclude that tumor resection with aortic reconstruction can be a choice for unresectable retroperitoneal tumors in children.

Aorta, Abdominal↗
PubMed1998

Intraoperative measurement of choline acetyltransferase activity to evaluate the functional status of donor nerve during reinnervated free muscle transfer: a preliminary report.

Intraoperative choline acetyltransferase activity measurements were used to evaluate the functional status of donor nerves during reinnervated free muscle transfer. This technique was applied to 3 cases. One was a lower-type brachial plexus injury in combination with radial nerve injury; the other 2 were Volkmann's ischemic contractures. Gracilis muscle was transferred for reconstruction of wrist extension in all cases. The donor nerves included 1 anterior interosseous nerve and 2 posterior interosseous nerves. A fascicle with choline acetyltransferase activity above 2,000 cpm was considered to be reliable as a motor fascicle. Reinnervation of transferred muscle was confirmed by electromyographic examination within the first 3.3 months (range, 2.5 to 4 months) after surgery and all muscles obtained useful recovery. This technique can directly and quantitatively verify the functional quality of the donor motor fascicle when the quality of the donor nerve is in doubt.

Adult↗
PubMed1998

Cortical motor neuron excitability during cutaneous silent period.

OBJECTIVE: To investigate cortical motor neuron excitability during cutaneous silent period (CSP), motor evoked potentials (MEPs) from abductor pollicis brevis following transcranial magnetic stimulation (TCM) were recorded with and without a conditioning of ipsilateral painful digital nerve electric stimulation. METHODS: MEPs following TCM were recorded with and without a conditioning stimulation at an interstimulus interval (ISI) from 0 ms to 100ms in 6 controls and four patients who had reduced pain sensation in unilateral upper limbs associated with cervical syringomyelia. In addition MEPs and evoked spinal cord potentials (ESCPs) from cervical epidural space following TCM with and without a conditioning stimulation were recorded in four patients with thoracic myelopathy. RESULTS: MEP amplitude was clearly attenuated by a conditioning stimulation at an ISI from 40 ms to 80 ms in controls (statistically significant at 60 ms). In patients with cervical syringomyelia, MEP amplitude was attenuated by a conditioning stimulation in asymptomatic hands similarly in controls but that was unchanged by a conditioning stimulation in the symptomatic hand with reduced pain sensation. In patients with thoracic myelopathy MEP amplitude was attenuated by conditioning stimulation similarly in controls, but ESCP amplitude was unchanged. CONCLUSIONS: We demonstrated that noxious cutaneous nerve stimulation suppressed spinal motor neurons but cortical motor neuron excitability was unchanged during CSP. In clinical practice, measurement of MEP suppression after noxious cutaneous nerve stimulation may provide useful information in patients with damaged pain related nerve fibers.

Adult↗
PubMed1998

Endoscopic harvest of saphenous vein graft for coronary artery bypass grafting: Saitama-Olympus technique.

OBJECTIVE: This study was undertaken to examine the clinical feasibility of a newly developed video-assisted endoscopic technique (Saitama-Olympus technique) to harvest saphenous vein graft (SVG) in 40 CABG patients. METHODS: There were 37 males and three females with an average age of 59+/-11 years. The special instruments developed were optical sheath, solid dilators, tunnel retractor, vessel dissector, GCC forceps which were utilized in conjunction with the thoracoscopic surgery system (Olympus, Tokyo, Japan). The course of the saphenous vein (SV) was marked on the skin prior to operation. SV was identified in the femoral region with a 4-cm skin incision and dissected with an open technique. The anterior surface of SV was dissected for 30 cm by the optical sheath mounted on the endoscope. Then another 4-cm skin incision above SV was placed in the popliteal region, resulting in a subcutaneous space over the SV. The subcutaneous space was then dilated and maintained with the tunnel retractor which has an endoscope channel at the top. With this system SV was visualized stably by endoscope without any assistance. All side branches were dissected and divided with the vessel dissector. When longer SVG is required, the same procedure was extended to the ankle with additional one or two skin incisions. RESULTS: SV was easily harvested in all patients with spending 15-84 min. The average number of skin incisions was 2.4+/-0.5 and the average length of the harvested SVG was 41+/-12 cm. The average number of bypassed grafts was 3.4+/-1.0 with use of left internal mammary artery (IMA) in 31 patients. The average operation time was 272+/-52 min, there were no significant prolongation relating to endoscopic SVG harvesting. The remainder of SVG in each patients was pathologically examined and there were no evidence of intimal injury. There were no major wound complications during the average follow-up of 10+/-4 months and this technique seemed to be advantageous for patients with less wound pain and better cosmetic appearance. CONCLUSIONS: The Saitama-Olympus technique to endoscopically harvest the SV is a clinically feasible surgical technique with the unique potential of a significant reduction in morbidity and decreased wound scarring in CABG patients.

Coronary Artery Bypass↗
PubMed1998

Endoscopic ligation for non-esophageal variceal upper gastrointestinal hemorrhage.

BACKGROUND: Endoscopic ligation can be used for bleeding lesions in non-fibrotic tissue; however, only small numbers of patients with non-esophageal variceal upper gastrointestinal hemorrhage have been treated in this way. To evaluate the utility of the technique, we performed the procedure to treat hemorrhage not from esophageal varices during emergency endoscopy. PATIENTS AND METHODS: Bleeding was identified from gastric Dieulafoy's ulcers (n=4), duodenal ulcers (n=3), gastric angiodysplasia (n=2) and Mallory-Weiss tears (n=3). The bleeding points were aspirated and controlled by endoscopic ligation and complete hemostasis was achieved in all cases. RESULTS: Although these lesions were located in difficult areas where endoscopic injection therapy and clipping sometimes fail, endoscopic ligation was performed easily and effectively without complications. Six of the patients had severe underlying disease, including acute and chronic myelogenous leukemia, liver cirrhosis and chronic renal failure; none suffered deterioration in their general condition after endoscopic ligation. CONCLUSIONS: Our findings suggest that endoscopic ligation is an easy and effective method of treatment for patients with gastrointestinal hemorrhage not from esophageal varices, and is safe even in patients with poor general health.

Adult↗
PubMed1998

Growth patterns and genetic changes of colorectal carcinoma.

BACKGROUND: Recent Japanese studies have shown that histogenesis of small colorectal carcinomas can be divided into two groups: polypoid growth arising from polypoid neoplasia, and nonpolypoid growth arising from flat or depressed neoplasia. This classification should be verified with genetic as well as morphologic characteristics. SUBJECTS AND METHODS: In order to classify our subject into polypoid growth and nonpolypoid growth types both histologically and endoscopically, we selected 42 colorectal carcinomas < 2 cm in size (35 submucosal and seven more advanced). Clinicopathological findings, presence or absence of Ki-ras gene mutation and overexpression of p53 protein were compared between the two types. RESULTS: Histologically, the cases were divided into 27 of the polypoid growth type and 15 of the nonpolypoid growth type. None of the nonpolypoid growth cases contained adenomatous remnant, wheras this was found in 75% of the polypoid growth cases. No Ki-ras mutation was observed in any of the nonpolypoid growth cases, although it appeared in 44% of the polypoid growth cases. Regarding the overexpression of p53 protein, no significant difference was observed between the two types. The histological and the colonoscopic polypoid growth-nonpolypoid growth classifications correlated well with each other (agreement rate 98%), except for one lesion, which was classified as polypoid growth type endoscopically but as nonpolypoid growth type histologically. CONCLUSIONS: The histologically defined polypoid growth-nonpolypoid growth classification may indicate a difference in pathway of colorectal carcinogenesis. Also, colonoscopic polypoid growth-nonpolypoid growth classification is available for preoperative estimation of the genetic characteristics of small carcinomas.

Adenoma↗
PubMed1998

Parasympathetic activity in brain death: effect of apnea on heart rate variability.

BACKGROUND: Power spectral analysis of heart rate variability is a useful monitoring of brain-damaged patients. However, the effect of artificial ventilation is not clearly demonstrated in assessing vagal activity because the locus of its activity is originated close to the respiratory center in the brain stem. We studied heart rate variability during artificial ventilation and apnea test as part of an assessment of brain death. METHODS: Ten adult patients with severe brain damage were studied. Power spectral analysis of heart rate variability from electrocardiographic R-R intervals was integrated to compare spectral components before, during and after the apnea test. Before the test, circulatory and blood gas variables and electrocardiographic recording were obtained under controlled mechanical ventilation at a rate of 12 and 18 (/min), each for 5 min. Measurements were made for 10 min during the apnea test, and repeated thereafter as before the test. Power spectral analysis based on fast Fourier transformation was made by integrating each low- (LF: 0.04-0.15 Hz) and high- (HF: 0.15-0.40 Hz) frequency band areas. LF was assessed as sympathetic and parasympathetic nervous activity, and HF as respiratory-related parasympathetic vagal activity. The HF/LF ratio showed sympathovagal balance. RESULTS: All patients were assessed as brain dead. During apnea, PaCO2 (P<0.01) and LF (P<0.05) increased, and pH (P<0.01) and HF/LF ratio (P<0.05) decreased. Heart rate, mean arterial pressure, PaO2 and HF remained consistent throughout. CONCLUSION: It was shown that sympathovagal balance was inclined to be sympathotonic during apnea, and that there were no changes in the respiratory-related vagal activity in spite of stopping artificial ventilation.

Adolescent↗
PubMed1998

Epidemiological analysis of Salmonella enteritidis isolates from humans and broiler chickens in Thailand by phage typing and pulsed-field gel electrophoresis.

To determine the phage types (PT) of Salmonella enteritidis found in Thailand and to clarify the potential for human infection by S. enteritidis in broiler chicken meat, human and poultry isolates taken from Thailand between 1990 and 1997 were phage typed and analyzed by pulsed-field gel electrophoresis (PFGE). Ten different PT were found among the 302 isolates phage typed, with PT 4 being the most frequent in human (73.9%) and poultry (76.2%) isolates, followed by PT 1 (8.0%), 8 (3.6%), and 7a (2.2%) in human isolates and by PT 7a (4.9%), 1 (3.7%), and 12 (2.4%) in poultry isolates. Of the 53 isolates analyzed by PFGE, 45 showed an indistinguishable pattern (pattern A) by BlnI-digested PFGE and the other 8 isolates showed a very similar pattern that differed by only a few bands. These results indicate the spread of a genetically identical clone of S. enteritidis in humans and poultry in Thailand.

Animals↗