Biomedical subjects

T Ishimoto

Publications and source records attributed to T Ishimoto.

At least 19 recordsLinked to original sources

PubMed2002

Arterial reconstruction in Buerger's disease: by-pass to disease-free collaterals.

BACKGROUND: Arterial reconstructions for ischemia in patients with Buerger's disease are technically challenging. This retrospective review was conducted to identify the critical factor for a successful outcome in bypass surgery for Buerger's disease. METHODS DESIGN OF STUDY: retrospective review. SETTING: University hospital, hospitalized patients. PATIENTS: since 1993, we performed 10 arterial reconstructions in 8 patients with Buerger's disease. There were 8 tibial artery bypasses and 2 collateral artery bypasses. One bypass was performed in the upper extremity. INTERVENTIONS: bypass surgery with autogenous vein graft. MAIN OUTCOMES MEASUREMENTS: graft patency. RESULTS: Over a mean follow-up period of 41.8 months, there were 3 graft occlusions. Of these, 2 were of bypasses to a patent but diseased tibial artery. One graft was occluded due to a toe stenosis which had been previously detected. The 2 collateral artery bypasses were patent at the last follow-up. CONCLUSIONS: In Buerger's disease, distal arterial reconstruction is frequently necessary to prevent ischemic limb loss. Collateral artery bypass is an option when the main arteries are affected by the disease. A patent but diseased artery should be avoided as a target for reconstruction.

Adult↗

PubMed2001

Kindling of the midbrain periaqueductal gray in rats.

We investigated the role of midbrain periaqueductal gray matter (PAG) in the manifestation of generalized seizures by administering electrical stimulation to this area in rats. Electrical stimulation of 60 Hz biphasic square pulses of a 1-s duration administered to the PAG-induced convulsive responses in the following order: (1) Type I, running (stimulus intensity; range 50--200 microA, mean 73.1 microA) without afterdischarge (AD), (2) Type IIa, running (stimulus intensity; range 50--300 microA, mean 111.8 microA) with AD at the PAG and the amygdala (AMY), and (3) Type IIb, generalized tonic--clonic seizures (GTCS) (stimulus intensity; range 50--250 microA, mean 182.1 microA) with AD at the PAG and AMY. Twenty daily PAG stimulations at the non-GTCS inducing threshold failed to produce kindling. However, 20 daily PAG stimulations at the GTCS threshold produced progressive AD spread involving the motor cortex, and progressive changes in the behavioral seizure pattern. These findings indicate that the PAG can be effectively kindled. However, PAG kindling has no apparent influence on subsequent AMY kindling.

Amygdala↗

PubMed2001

Staged vascular reconstruction along with repeatedly performed angiography to prevent ischemic limb loss with Buerger's disease: report of a case.

An aggressive approach to vascular reconstruction should be adopted in patients with Buerger's disease and peripheral ischemia who are often young and otherwise active. A patient with severe Buerger's disease is reported who was treated successfully by complete vascular reconstruction with staged bypass surgery while also performing repeated angiography to preserve the foot function. A 48-year-old man with Buerger's disease presented with necrosis of the foot. Angiography showed occlusion of the right distal external iliac artery and no runoff below the knee. Repeated angiography after performing a lumbar sympathectomy demonstrated patency of the distal portion of the deep femoral artery. Angiography was again performed after a reconstruction of the deep femoral artery and patency of the anterior tibial artery was observed. A staged bypass operation on the tibial artery was therefore able to achieve a prompt healing of both the toe ulcers and plantar wound.

Angiography↗

PubMed2001

Inflammatory solitary iliac artery aneurysms: a report of two cases.

Inflammatory abdominal aortic aneurysms are associated with atherosclerosis, which are characterized by specific clinical manifestation. We treated two patients with unilateral solitary iliac artery aneurysms with perianeurysmal fibrosis which compressed the ureter resulting in ipsilateral hydronephrosis. After the iliac artery aneurysm was repaired with a prosthetic graft, the hydronephrosis resolved. Microscopically, there was clear evidence of atherosclerosis in one case. There was a characteristic inflammatory reaction around the adventitia in both aneurysms. Localized iliac perianeurysmal fibrosis has not been particularly described. The clinicopathologic similarities between these cases and inflammatory abdominal aortic aneurysms suggest the same pathogenesis.

Aged↗

PubMed2001

HET0016, a potent and selective inhibitor of 20-HETE synthesizing enzyme.

The present study examined the inhibitory effects of N-hydroxy-N'-(4-butyl-2-methylphenyl)-formamidine (HET0016) on the renal metabolism of arachidonic acid by cytochrome P450 (CYP) enzymes. HET0016 exhibited a high degree of selectivity in inhibiting the formation of 20-hydroxy-5,8,11,14-eicosatetraenoic acid (20-HETE) in rat renal microsomes. The IC(50) value averaged 35+/-4 nM, whereas the IC(50) value for inhibition of the formation of epoxyeicosatrienoic acids by HET0016 averaged 2800+/-300 nM. In human renal microsomes, HET0016 potently inhibited the formation of 20-HETE with an IC(50) value of 8.9+/-2.7 nM. Higher concentrations of HET0016 also inhibited the CYP2C9, CYP2D6 and CYP3A4-catalysed substrates oxidation with IC(50) values of 3300, 83,900 and 71,000 nM. The IC(50) value for HET0016 on cyclo-oxygenase activity was 2300 nM. These results indicate that HET0016 is a potent and selective inhibitor of CYP enzymes responsible for the formation of 20-HETE in man and rat.

Amidines↗

PubMed2001

Identification of the critical spinal arteries with F wave-polysynaptic response complex monitoring: an experimental study.

PURPOSE: The main cause of paraplegia after surgery for descending thoracic aortic aneurysms and thoracoabdominal aortic aneurysms is spinal cord ischemia caused by ligation of the critical spinal arteries that are associated with the great radicular artery (GRA). In this experimental study, we attempted to identify the critical spinal arteries with F wave-polysynaptic response complex (FPC) monitoring. The FPC, which we are using as a monitor of spinal cord ischemia, is myogenic potentials evoked by the tibial nerve stimulation through the anterior horn cells. METHOD: In 18 rabbits, infrarenal lumbar arteries were clamped until there was an FPC amplitude reduction (FPCAR) of at least 60%. The rabbits were classified according to the number of arteries clamped to produce the FPCAR (group A, 1 artery; group B, 2 arteries; group C, 3 arteries). Selective angiography of each lumbar artery was performed in all rabbits. RESULTS: An FPCAR was observed in all 18 rabbits. In all nine rabbits in group A, the FPCAR was caused by the clamping of one particular lumbar artery. The GRA was shown by means of selective angiography to originate directly from this lumbar artery. In the nine rabbits in groups B and C, 11 FPCARs were observed. Of these, nine FPCARs in nine rabbits were caused by the clamping of lumbar arteries that included the vessel from which the GRA originated. CONCLUSION: Temporary clamping of lumbar arteries with FPC monitoring can be used as a means of detecting the critical spinal arteries from which the GRA originates.

Action Potentials↗

PubMed2000

Convulsive seizures induced by N-methyl-D-aspartate microinjection into the mesencephalic reticular formation in rats.

Effects of microinjections of a single 2 or 10 nmol dose of N-methyl-D-aspartate (NMDA) into the unilateral mesencephalic reticular formation (MRF) on behavior and electroencephalogram were examined in rats (n=18) during a 15 min period (Exp. 1), and subsequent effects of sound stimulation with key jingling applied at 15, 30, and 45 min after the injections were observed (Exp. 2). The microinjections of 2 nmol dose of NMDA (n=10) induced hyperactivity (9 of 10 rats) and running/circling (8 of 10 rats) in Exp. 1, and hyperactivity (3 of 10 rats) in Exp. 2. Moreover, the microinjections of 10 nmol dose of NMDA (n=8) induced not only hyperactivity (8 of 8 rats) and running/circling (7 of 8 rats) but also generalized tonic-clonic seizures (GTCS) (5 of 8 rats) in Exp. 1; these seizure patterns were also elicited by sound stimulation in Exp. 2. The seizure patterns were accompanied by electroencephalographic seizure discharges in the MRF and the motor cortex. In contrast, the control group rats (n=10) which received a single dose of saline microinjection into the unilateral MRF showed no behavioral or electroencephalographic changes in both Exp. 1 and 2. These findings suggest that the MRF has an important role in the development of GTCS, which follows hyperactivity and running/circling, and that potentiation of excitatory neurotransmission in the MRF participates in the development of audiogenic seizures as well as GTCS.

Acoustic Stimulation↗

PubMed2000

Dendritic translocation of the rat ferritin H chain mRNA.

To elucidate the mechanism regulating the selective transport of mRNAs to synaptic sites, we compared the synaptosomal mRNAs with those from the forebrain using the differential display method. The ferritin H chain mRNA was found to be highly enriched in the synaptosomes. In situ hybridization for the ferritin H chain mRNA in the cultured dissociated neurons and in the hippocampal brain slices demonstrated its existence in the dendritic region. These data clearly indicate the selective translocation of the ferritin H chain mRNA into the dendrites and suggested the local expression of ferritin at the synapse.

Animals↗

PubMed2000

Anomalies of inferior vena cava and left renal vein: risks in aortic surgery.

Although most aortic surgery is now routinely performed without incident, major venous anomalies can cause unexpected bleeding. In the last 6 years, 4 of 166 patients undergoing abdominal aortic surgery at our institution were found to have a major venous anomaly, including a double inferior vena cava (2), a preaortic iliac vein confluence (1), and a circumaortic renal collar (1). The 3 men and 1 woman had a mean age of 62.3 years (range, 56 to 68 years). All four patients underwent surgery for an abdominal aortic aneurysm. Preoperative imaging revealed all of the venous anomalies except for the renal collar. Unexpected venous injuries complicated the operation in one patient who had a double inferior vena cava and an inflammatory abdominal aortic aneurysm and in the patient with the circumaortic renal collar. Major venous anomalies are rarely encountered in patients undergoing aortic surgery. Preoperative assessment and intraoperative awareness are important to prevent unexpected venous injuries. Patients with an anomaly of the left renal vein and an inflammatory abdominal aortic aneurysm are at a particularly high risk.

Aged↗

PubMed2000

Causes of late mortality in patients with disabling intermittent claudication.

The long-term prognosis of patients suffering from intermittent ischemic claudication is reportedly worse than that of the normal population. The outcome of patients with ischemic claudication admitted to hospital was reviewed retrospectively to identify the causes of late death. The cumulative survival rates for patients with claudication were 94.6% at 1 year, 79.4% at 3 years, 67.3% at 5 years and 37.4% at 10 years. The 3 major causes of death, that is, ischemic heart disease, malignancy, and cerebrovascular accident, were equally common. The younger patients tended to die of ischemic heart disease, whereas the older patients died of cerebrovascular accidents. Malignancies caused a similar number of late deaths in all age groups. These results suggest that specific care should be given to patients with intermittent claudication based on the age-related causes of death.

Actuarial Analysis↗

PubMed2000

Rupture of infected pseudoaneurysms in patients with implantable ports for intra-arterial infusion chemotherapy.

Intra-arterial hepatic chemotherapy via implantable reservoirs is being used increasingly. In our department, five patients have undergone emergency surgery since 1991 because of rupture of an infected pseudo-aneurysm at the site of entry of the catheter. Surgical procedures included removal of the catheter and the reservoir, and closure of the affected artery with or without reconstruction. Of these patients, three (60%) died from uncontrollable sepsis. The poor prognosis emphasizes the need, in patients with carcinoma, for strict aseptic technique and hemostasis at the time of catheter placement, and for careful device maintenance.

Adult↗

PubMed1999

Simultaneous repair of arch and abdominal aortic aneurysms. A simple new technique using a temporary bypass graft.

OBJECTIVE: Atherosclerotic aneurysms in the aortic arch are associated with abdominal aortic aneurysms in up to 37% of cases. We have developed a single-stage approach to the repair of both aneurysms using a temporary bypass. SUBJECTS: Since November 1996, 5 patients underwent simultaneous repair of aneurysms in the aortic arch and in the infrarenal abdominal aorta, using a new temporary bypass graft technique. Entire arch replacement with simultaneous abdominal aortic aneurysmectomy was performed in one patient. The other 4 patients underwent distal hemi-arch replacement distal from the orifice of the brachiocephalic artery with simultaneous repair of the abdominal aortic aneurysm. METHOD: For the entire arch replacement procedure, blood flow to all major branches of the aortic arch was established using a bifurcated graft. This graft anastomosed to the ascending aorta was used as the proximal inflow of the temporary bypass graft. For the hemi-arch replacement procedure, the proximal inflow segment of the temporary bypass graft was anastomosed to the brachiocephalic artery. In both cases, the distal outflow segment of the temporary bypass graft was the graft used for repair of the abdominal aortic aneurysm. In order to prevent any clamp injury, Teflon felt was tightly wrapped around the aorta before the clamp was applied. RESULTS: Evaluation of the hemodynamic parameters measured during cross-clamping of the aortic arch revealed stable distal perfusion to the visceral organs and no excessive increase in cardiac afterload. All patients had an uneventful postoperative course and were discharged within 1 month of surgery. CONCLUSION: Our temporary bypass method is recommended for simultaneous replacement of aneurysms in the aortic arch and the abdominal aorta.

Aged↗

PubMed1999

Retrocaval ureter and preaortic iliac venous confluence in a patient with an abdominal aortic aneurysm.

Anomalous anatomic location of a large venous system poses a potential hazard in aortic operations. We encountered a patient with an infrarenal abdominal aortic aneurysm who was also found at preoperative contrast-enhanced computed tomography to have a retrocaval right ureter and a preaortic iliac vein confluence. This combined anomaly has not previously been reported except for one postmortem case. As abdominal aortic surgery is currently performed routinely, care must be taken to avoid injury to surrounding organs due to rare anatomic anomalies.

Abnormalities, Multiple↗

PubMed1999

Molecular typing of methicillin-resistant Staphylococcus aureus in a university teaching hospital.

Plasmid analysis and pulsed-field gel electrophoresis (PFGE) were used to study the epidemiologic relationship among methicillin-resistant Staphylococcus aureus (MRSA) strains isolated at Tokyo Medical and Dental University Hospital. We found that 263 of 276 MRSA isolates had plasmids, which could be classified into 30 different patterns according to the number and plasmid molecular weight. Strains which harboured a single plasmid of approximately 13.4 Mds in molecular weight were the most numerous (55.7% of the isolates). These strains were isolated from 14 of 17 hospital wards. The largest number of strains with this plasmid pattern (33 strains) were isolated from a single ward. PFGE typing was then performed to further confirm the relationships among these 33 strains. The PFGE banding patterns of these strains were highly similar. The antibiogram profiles of these strains were also correlated with the PFGE pattern. Thus, the results suggest that these strains are epidemiologically related and spread throughout the ward. Combined plasmid analysis and PFGE were effective for discriminating the various MRSA isolates.

DNA, Bacterial↗

PubMed1998

HSP90 has neurite-promoting activity in vitro for telencephalic and spinal neurons of chick embryos.

We purified a protein from the extract of denervated chick muscle. The protein had neurite-promoting activity in vitro for the chick telencephalic neurons and spinal neurons. Partial amino acid sequencing and immunoblotting revealed that the protein was chick heat shock protein 90 (HSP90). Commercially available bovine HSP90 and recombinant chick HSP90 expressed in Escherichia coli also showed the same activity. Since HSP10 (GroES) and HSP60 (GroEL) exhibited no activity for neurite outgrowth in the same culture, this activity was specific to HSP90 among the heat shock proteins.

Amino Acid Sequence↗

PubMed1998

Abdominal aortic aneurysm repair with arterial branch reconstruction: utility of the temporary bypass technique.

Between June 1992 and May 1996, five patients underwent an abdominal aortic aneurysm (AAA) repair with concomitant arterial branch reconstruction. All of the patients were males ranging in age from 55 to 66 years (mean: 61.6 years). The operations were performed for a localized abdominal aortic dissection, a pseudoaneurysm after patch angioplasty of a supraceliac AAA, a pararenal AAA, a total AAA with retrograde descending thoracic aortic dissection, and a supraceliac AAA after an infrarenal AAA repair. All patients underwent bilateral renal artery (RA) reconstruction. Three patients also had a concomitant reconstruction of the superior mesenteric artery ad celiac axis. The renal arteries were preferentially reconstructed. Visceral circulation during aortic cross-clamping was maintained via a temporary bypass circuit. A temporary division of the left renal vein was necessary in two patients. Overall, the mean renal ischemia time was 17.2min (range: 10 to 32 min). There was one perioperative death due to sepsis from a graft infection. Another patient died 6 months postoperatively due to pyothorax. One patient required postoperative hemodialysis for 1 month. Based on the above findings, the temporary bypass technique is thus considered to be useful for maintaining physiologic organ perfusion during aortic clamping without the need to use any complicated devices.

Aged↗

PubMed1998

A case of insufficient sleep syndrome.

All night polysomnographic evaluation (PSG) soon after admission and at the late period of admission revealed an atypically high sleep efficiency and a prolonged total sleep time. Sleep onset latency and distribution of REM and NREM sleep stages were like those of normal sleepers. On REM latency, while it was remarkably reduced (25.0 min) soon after admission and sleep onset REM period (SOREMP) was found, at the late period of admission it was prolonged and SOREMP was not found. Giving multiple sleep latency test with polysomnography, soon after admission subjective excessive daytime sleepiness had already improved and mean sleep latency (13.2 min) was within normal range. However, SOREMP appeared twice in five tests. We considered that the appearance at the early period of admission was the result of REM pressure growing.

Adult↗

PubMed1997

In vitro and in vivo evidence for high frequency of I-Ab-reactive CD4+ T cells in HLA-DQ or HLA-DRA transgenic mice lacking endogenous MHC class I and/or class II expression.

Although T cells are educated to recognize foreign antigenic peptides in the context of self MHC molecules during their development in the thymus, peripheral T cells also recognize allo- and xeno-MHC molecules. The lower frequency of xeno-MHC-reactive T cells than that of allo-MHC-reactive T cells is often explained by the difference in the degree of homology between xeno- or allo-MHC and self MHC molecules, as well as by the species barrier of the molecules involved in immune recognition. To distinguish these two possibilities, we estimated the frequency of I-Ab-reactive CD4+ T cells selected by HLA-DQ or DR alpha E beta b molecules, using HLA-DQ6 and HLA-DRA transgenic C57BL/6 (B6) mice lacking endogenous MHC class I and/or class II molecules (DQ6A0/0 and DR alpha 30A0/0 beta 20/0). CD4+ lymph node T cells from DQ6A0/0 and DR alpha 30A0/0 beta 20/0 showed the strong proliferative response to I-Ab molecules. In addition, DQ6A0/0 and DR alpha 30A0/0 beta 20/0 rejected the skin graft from mice expressing I-Ab molecules irrespective of MHC class I expression, indicating that the CD4+ T cells recognizing I-Ab molecules are directly involved in this rejection. The estimated frequency of I-Ab-reactive CD4(+)CD8- thymocytes in DR alpha 30A0/0 beta 20/0 and DQ6A0/0 was comparable with that observed in the MHC class II-disparate strains. Our findings thus indicate that CD4+ T cells selected to mature on xeno-MHC class II molecules such as HLA-DQ6 or DR alpha E beta b, when these molecules are expressed in mice, recognize I-Ab molecules as allo-MHC class II, despite the less structural homology.

Animals↗