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Biomedical subjects

Kenji Okada

Publications and source records attributed to Kenji Okada.

At least 55 records · Page 3Linked to original sources
PubMed2005

Cold saline injection attenuates motor-evoked potential in the spinal cord by cortical electrical stimulation in the dog.

Changes in the motor-evoked potential of the spinal cord with transcranial stimulation are monitored for spinal cord function during thoracoabdominal aortic aneurysm surgeries. We examined the effects of changes in motor-evoked potential with cold saline injected into the clamped segment of the aorta, and compared the effects to lidocaine and warm saline injection. Eighteen dogs were divided into three groups according to the injected agents: Warm saline group (37 degrees C, 20 ml), Cold saline group (4 degrees C, 20 ml), and Lidocaine group (5.0 mg/kg of lidocaine in 20 ml of warm saline), (n=6, each group). Changes in the peak-to-peak MEP amplitude and the indirect wave (I wave) amplitude were measured during aortic cross-clamping. In the peak-to-peak MEP amplitude, the cold saline and lidocaine groups attenuated to 80% of the control value but were not significantly changed. In the I wave amplitude, the cold saline group showed a significant attenuation 1 min after injection (p<0.0001) and the lidocaine group 4 min after injection (p=0.0230), when compared with the warm saline group. Attenuation of the I wave amplitude in the cold saline group was significantly larger than that in the lidocaine group (p=0.0003). Changes in the I wave amplitude appeared within 4 min in both the cold saline and lidocaine groups. Cold saline injection into the clamped segment of the aorta is a diagnostic procedure for determining presiding critical arteries in the segment without experiencing the pharmacological side effects observed with lidocaine injection.

Animals↗
PubMed2004

Successful coil embolization for spontaneous arterial rupture in association with Ehlers-Danlos syndrome type IV: report of a case.

When a patient with Ehlers-Danlos syndrome (EDS) presents with a vascular emergency, performing life-saving surgery can be difficult because of the profound fragility of the arterial tissue. We report the case of a 27-year-old woman with EDS in whom a spontaneous arterial rupture was successfully treated with transcatheter embolization. The patient was brought to our hospital in shock, with left lower abdominal pain. She had been diagnosed with EDS type IV following a colonic rupture 8 years earlier. An emergency angiogram revealed rupture of the left external iliac artery. The active bleeding was managed by transarterial embolization of the ruptured artery using stainless steel coils, which took 30 min to achieve. The patient has not suffered any further vascular complications during the year since this procedure. Transcatheter coil embolization may be a reliable option for treating sudden arterial rupture in patients with this syndrome.

Adult↗
PubMed2004

Successful shrinkage of distal arch and proximal descending aortic aneurysm after transaortic endovascular stent-grafting.

OBJECTIVES: Although endovascular stent-grafting is available for atherosclerotic thoracic aneurysms, it is unknown whether the excluded thrombosed aneurysms shrink. We evaluated serial changes in distal aortic arch or proximal descending aortic aneurysms excluded space after transaortic stent-grafting. METHODS: Thirty-four patients with true distal aortic arch or proximal descending thoracic aortic aneurysms were treated by stent-grafts introduced via proximal arch aortic incisions. Follow-up included computed tomographs (CT) every 6 months in 31 patients. The maximum dimensions for excluded space and aneurysmal diameters were measured and evaluated to determine whether the aneurysmal space had decreased or shrunken following this alternative procedure. RESULTS: Two hospital deaths (5.9%) were caused by a cerebral embolism and a peri-operative myocardial infarction. Another case died from pneumonia a year after surgery. Thirty-one cases (91%) survived during follow-up, but one case suffered from paraplegia (2.9%). The follow-up period ranged from 10 to 72 months (average 39.3+/-27.2 months). There were no aneurysmal ruptures during follow-up. Post-operative serial CTs showed a disappearance or a significant shrinkage of the excluded aneurysmal space in 30 of the 31 cases (97%); one case suffered endoluminal leakage. CONCLUSIONS: Transaortic endovascular stent-grafting is feasible for distal aortic arch or proximal descending aortic aneurysms. The excluded aneurysmal space disappears or shrinks after successful stent-graft placement.

Aged↗
PubMed2004

Early type A dissection with the aortic connector device.

A 75-year-old woman who had suffered type B dissection had coronary artery bypass grafting surgery using a mechanical aortic connector. Four days after the operation, she had a sudden syncope. CT demonstrated type A dissection, and an emergency operation was done, and postoperative course was uneventful. This case demonstrates that this connector should be used carefully in patients with a history of type B dissection.

Aged↗
PubMed2004

Near-infrared spectroscopy for monitoring cerebral ischemia during selective cerebral perfusion.

OBJECTIVE: To minimize the neurological complications following cardiovascular surgery, it is essential to prevent an occurrence of cerebrovascular embolism and to detect and solve cerebral malperfusion without delay in the operating theater. Although we have introduced near-infrared spectroscopy (NIRS) monitoring for the purpose of detecting cerebral malperfusion, no criterion has been available. We searched for this criterion by examining the relationship of sustained drop in the regional oxygen saturation (rSO2) of the frontal lobes to the occurrence of neurological events. METHODS: The 59 consecutive patients undergoing aortic surgery with selective cerebral perfusion (SCP) were examined. The rSO2 was monitored throughout the surgery and the durations of drops in rSO2 to below 55% and those below 60% were determined for each patient. The durations of rSO2 drop and other surgery-related parameters were compared between the patients in whom neurological events occurred and those without such events. RESULTS: A total of 16 cases (27.1%) presented with neurological events. Newly developed cerebral infarction was documented in 6 of these 16 cases. Operation time and the durations for which rSO2 dropped were significantly longer for the 16 patients with neurological events than for the 43 patients without events (Op time: 546.8 versus 448.1 min, P=0.0064; rSO2 below 60%: 141.2 versus 49.8 min, P=0.0032; rSO2 below 55%: 66.6 versus 10.6 min, P=0.0011), while there was no significant difference in age, bypass time, aortic clamping time, SCP time, and circulatory arrest time between the two groups. In the 3 patients with infarcts suggestive to hypoperfusion, sustained decrease in rSO2 was observed, while it was not significant in the remaining 3 patients with infarcts suggestive to embolism. Among the 53 patients without infarction, transient neurological events occurred more frequently in patients with sustained drop in rSO2 below 55% for over 5 min (44.4% versus 5.7%, P=0.0014). CONCLUSIONS: A sustained drop in rSO2 during aortic surgery is closely related to the occurrence of neurological events following surgery. We recommend that recovery of drop in rSO2 below 55% should be addressed without delay. However, use of NIRS is limited for detecting embolic events or hypoperfusion in the basilar region.

Adult↗
PubMed2004

[Susceptibility testing and molecular epidemiology of clinical strains of Bordetella pertussis isolated in Japan from 2001 to 2002].

We determined antimicrobial susceptibilities and analyzed molecular epidemiology of 26 strains of Bordetella pertussis clinically isolated and then performed pulsed-field gel electrophoresis (PFGE) in Japan (Japanese Pertussis Surveillance Group Participants), from 2001 to 2002. The MICs of erythromycin, clindamycin, tetracyclines, fluoroquinorones, trimethoprim-sulfamethoxazole and rifampicin of all isolates against these showed 1 microgram/ml or less. Sparfloxacin is the most potent agent, of which the MICs showed 0.008-0.016 microgram/ml. Results of DNA fingerprinting by pulsed-field gel electrophoresis (PFGE) differentiated three types (Type I; 11 strains (42%), type II; 14 strains (54%) and type III; 1 strains (4%)). However, no relation between regions and identical PFGE patterns was found in this study. Further, surveillance of the antimicrobial susceptibilities and molecular epidemiology of B. pertussis will be required.

Anti-Bacterial Agents↗
PubMed2004

Seroepidemiologic study on pertussis, diphtheria, and tetanus in the Fukuoka area of southern Japan: seroprevalence among persons 0-80 years old and vaccination program.

In Japan, mass vaccination for diphtheria, pertussis, and/or tetanus has been mandated by the Vaccination Law since 1948. In order to evaluate the efficacy of this vaccination policy, we conducted seroepidemiological studies on pertussis, diphtheria, and tetanus among individuals aged 0 - 80 years. The pertussis toxin seropositive rates of the vaccine-eligible groups and vaccine-ineligible groups were 55.0 and 57.9%, respectively. The seropositive rate of each group for diphtheria antitoxin was 76.3 and 75.7%, respectively. The tetanus antitoxin seropositive rates were 91.7 and 10.5%, respectively, showing a significant difference between the two groups (P < 0.001). For the three diseases, variations were seen between age groups in the geometric mean antibody titers due to changes of the vaccination program. The results of this study show that natural Bordetella pertussis infection has occurred more frequently than expected. In order to establish the most appropriate vaccination program for the control of pertussis, diphtheria, and tetanus in Japan, further evaluation is necessary.

Adolescent↗
PubMed2003

Fate of aneurysms of the distal arch and proximal descending thoracic aorta after transaortic endovascular Stent-Grafting.

BACKGROUND: The purpose of this study was to evaluate the midterm results of transaortic stent-grafting for distal aortic arch aneurysms or proximal descending aortic aneurysms and the feasibility of this method for thoracic aortic aneurysm repair. METHODS: Twenty-three patients with true distal aortic arch aneurysms or proximal descending thoracic aortic aneurysms were repaired with the stent-graft introduced through the incision on the proximal arch aorta. Follow-up computed tomography was performed every 6 months in 21 surviving patients. The maximum dimension of the excluded aneurysmal space and the maximum aneurysmal diameter were measured and evaluated to determine whether the aneurysmal space decreased or disappeared after this alternative procedure. RESULTS: There was 1 hospital death (4.3%) due to cerebral embolism. Another patient died of pneumonia 1 year after surgery. Twenty-one patients (91%) survived during the follow-up period, but 1 patient (4.3%) suffered from paraplegia. The follow-up period ranged from 12 to 62 months (average, 34.3 +/- 15.2). There were no instances of aneurysmal rupture during the follow-up period. Postoperative serial computed tomography scans showed disappearance or significant shrinkage of the excluded aneurysmal space in 20 of 21 patients (95%), except for the one patient with endoluminal leakage. CONCLUSIONS: Transaortic endovascular stent-grafting was an effective alternative approach to treating distal aortic arch aneurysms or proximal descending aortic aneurysms. The excluded aneurysm disappeared or shrunk after successful placement of the stent-graft.

Aged↗
PubMed2003

WinLALS for a linked-atom least-square refinement program for helical polymers on WINDOWS PCs.

Fiber diffraction dada from polymers are sufficiently different in kind and quantity from single crystal data as to warrant analyses with a different emphasis: refinement of competing molecular models where torsion angles and bond angles are the explicit variables rather than atomic coordinates. The first linked-atom least-squares (LALS) refinement program had been devolved at Arnott's laboratories at King's College London [Arnott, S., Wonacott, A.J., 1966a. Polymer 7, 157] on mainframe and several revised versions were maintained at Purdue University [Smith, P.J.C., Arnott, S., 1978. Acta Crystallogr. Sect. A 34, 3; Chandrasekan, R. 2000. LALS Users Manual, Whistler Centre for Carbohydrate Researchm Purdue University, West Lafayette, IN] on workstation. Today the LALS users have to choose correctly any one program that they want to use, trigonometric or Bessel functions, from some versions. To develop a new WinLALS program based on the dimensioned version of the latest LALS2000 program [LALS Users Manual (2000)], we reviewed all the mathematical expressions and corrected the optimization of the non-bonded atomic contact terms. The WinLALS is coded with FORTRAN 90 and runs on MICROSOFT-WINDOWS PCs and the many amendments including changing input/output assignments, expanding array sizes, arranging that the update files have all output parameters of each cycle, and correcting several bugs are performed. This paper describes the mathematical expressions in detail employed in WinLALS and compares results of its applications obtained with those obtained earlier.

Journal Article↗
PubMed2003

Transbrachial arterial insertion of aortic occlusion balloon catheter in patients with shock from ruptured abdominal aortic aneurysm.

OBJECTIVE: Of 125 surgical patients with abdominal aortic aneurysm (AAA) treated from 1999, 11 patients with deep shock from ruptured AAAs who underwent aortic occlusion balloon catheter (AOBC) insertion before laparotomy were studied. METHODS: With the patients under local anesthesia, the brachial artery was exposed and the balloon catheter was inserted into the thoracic aorta. The balloon was inflated halfway and pulled back gently to the orifice of the left subclavian artery, and was advanced with the aid of blood flow down to the abdominal aorta. After full inflation of the balloon, the catheter was pulled until the balloon was fixed at the proximal shoulder of the AAA. RESULTS: AOBC insertion was completed within 16.1 +/- 5.1 minutes. Systolic blood pressure at presentation was 84.1 +/- 31.7 mm Hg, deteriorated to 60.9 +/- 15.4 mm Hg on arrival in the operating room, and increased significantly (P <.0001) to 123.4 +/- 25.3 mm Hg after AOBC insertion. The balloon burst in three patients. Embolic complications were observed in two patients. There were three deaths, two associated with the balloon bursting. In nine patients whose shock was successfully controlled by AOBC, operative mortality was 11%. CONCLUSION: Transbrachial arterial insertion of an AOBC may be useful to ameliorate hemorrhagic shock in patients with ruptured AAAs.

Aged↗
PubMed2003

Retro-sartorius bypass in the treatment of graft infection after peripheral vascular surgery.

Extra-anatomic bypass is preferred for revascularization after removal of infected vascular grafts. The obturator canal technique has been used to bypass an infected field in the groin, although this method has not always been definitive because of several drawbacks. We present a unique method of extra-anatomic revascularization for use in such a situation. An autogenous graft is placed just below the sartorius muscle in the thigh and penetrates the iliacus muscle near the lateral end of the inguinal ligament. Limb loss and recurrent infection are prevented postoperatively. This retro-sartorius bypass technique may be a useful alternative to obturator bypass grafting in selected patients.

Aged↗
PubMed2003

Rib-cross thoracotomy for replacement of the thoracoabdominal or total descending aorta.

We describe the use of rib-cross thoracotomy and costal coaptation pins made with bioabsorbable poly-L-lactide for rib approximation. This thoracotomy provided an excellent intraoperative exposure of the entire descending aorta and thoracoabdominal aorta in patients with extended thoracoabdominal aortic aneurysm without increase in postoperative morbidity.

Absorbable Implants↗
PubMed2003

Surgical treatment of aortic coarctation associated with multi-vessel brachiocephalic involvement in takayasu's arteritis.

In Takayasu's arteritis (TA), both atypical coarctation (CO) and brachiocephalic involvement are common features that occasionally require operative correction. A combination of these abnormalities could duplicate underlying illness in patients, posing an increased risk of operative morbidity. We present, herein, two TA patients in which hypertensive heart disease secondary to CO was surgically corrected. Both patients had multi-vessel brachiocephalic disease. One patient who showed occlusion of all brachiocephalic arteries underwent aorto-aortic bypass, while another with two-vessel lesion underwent axillo-bifemoral bypass grafting. Subclavian reconstruction was supplemental to each procedure, resulting in relief of neurologic stigmata. Strategies to avoid intraoperative cerebral ischemia played an important role in the surgical repair of such TA-related extensive vascular lesions.

Aortic Coarctation↗
PubMed2003

Trans-vertebral regional cooling for spinal cord protection during thoracoabdominal aortic surgery: an experimental study.

We developed a simple cooling method for spinal cord protection against ischemic injury during aortic surgery. The neuroprotective effects of our method were investigated using an animal study. Selective spinal hypothermia was produced by means of originally-designed cooling pads placed over the lower thoracic and lumbar vertebral column. Spinal cord ischemia was induced by cross-clamping the thoracic aorta for 60 min in beagle dogs. The neuroprotective effects were evaluated by a multi-modal study. The motor-evoked potentials of the spinal cord resulting from transcranial electric stimulation (MEPs) were recorded during both the ischemic and reperfusion periods. Hindlimb motor function was graded with the Tarlov score, and a histologic examination of the spinal cord injury was performed, at 24 hours after ischemia in animals undergoing hypothermia (hypothermia group: n = 7) or a sham (control group: n = 7). The spinal cord temperatures at the lower thoracic (T10) and lumbar (L3) levels decreased by -9.1 degrees C per hour and -8.1 degrees C per hour, respectively. The amplitude of the MEPs decreased during ischemia in both groups of animals, and significantly recovered during the early phase of aortic reperfusion in the hypothermia group. The Tarlov scores in the hypothermia and control groups were 3.3 +/- 1.0 and 1.1 +/- 1.5 (mean +/- SD, p = 0.015), respectively. Histopathologic study revealed that ischemic injury of the lumbar cord was reduced in the animals undergoing hypothermia. Trans-vertebral regional cooling reduced ischemic spinal cord injury in a canine study. The current method is potentially feasible for clinical use, especially in view of its technical simplicity and few procedure-related complications.

Animals↗
PubMed2002

Enhanced sensitisation of mice with diphtheria tetanus acellular pertussis vaccine to local swelling reaction to the booster immunisation.

Severe local swelling has been regarded as a serious safety problem for the booster immunisations of diphtheria tetanus acellular pertussis combined (DTaP) vaccine and DT combined toxoids (DT-td). We attempted to search for the factor of DTaP vaccines possibly contributing to the enhanced local reaction by using the mouse hind paw swelling reaction. Mice were immunised intramuscularly with DTaP vaccine twice at 1-month interval and were challenged their hind paw with one of the antigens of DTaP vaccine 2 weeks later. D-td was shown to elicit the strongest swelling among the vaccine antigens. No causal relationship was found between the swelling and the level of immunoglobulin G (IgG) or IgE in mice. Residual pertussis toxin (PT) activity of DTaP vaccines for immunisation was shown to play a role in the enhanced sensitisation of mice to the D-td-related hind paw swelling.

Animals↗
PubMed2002

Cold blood spinal cord plegia for prediction of spinal cord ischemia during thoracoabdominal aneurysm repair.

BACKGROUND: This clinical study was undertaken to evaluate changes in motor evoked potentials (MEPs) during cold blood infusion into a thoracoabdominal aortic aneurysm. We also determined the efficacy of this infusion method for predicting spinal cord injury during thoracoabdominal aortic aneurysmal surgery. METHODS: We monitored descending evoked spinal cord potentials (ESCPs), segmental ESCPs, and MEPs during the prosthetic replacement phase of thoracoabdominal aneurysmal surgery. We perfused cold blood (4 degrees C, 300 to 450 mL) into aneurysms after clamping the aorta, while monitoring spinal cord potentials in 6 cases of thoracoabdominal aortic aneurysm. If the spinal cord potentials decreased during infusion of cold blood, we reconstructed the intercostal arteries in the aneurysm. If the potentials did not change during the infusion of cold blood and after the aneurysmectomy, we did not reconstruct the intercostal arteries and ligated all of them. RESULTS: Postoperative paraplegia did not occur in any case. The MEPs decreased in amplitude after infusion of cold blood in 3 cases, but amplitude recovered after reconstruction of the intercostal arteries. The other 3 cases did not show any change after infusion of cold blood, and all of the intercostal arteries in the aneurysm were ligated. CONCLUSIONS: Cold blood infusion into the aneurysm while monitoring MEPs was a useful adjunct to detect the presence of critical intercostal arteries and to facilitate thoracoabdominal aortic aneurysmal surgery.

Aged↗
PubMed2002

Surgical treatment of atypical aortic coarctation associated with occlusion of all arch vessels in Takayasu's disease.

We report a patient with Takayasu's disease surgically treated who had presented severe manifestation due to aortic coarctation associated with occlusion of all arch branches. This patient had suffered cardiac failure and recurrent fainting attacks before surgery. The operative procedures included ascending to infra-renal aortic bypass grafting combined with reconstruction of the right axillary artery. Cardio-pulmonary bypass (CPB) was used to facilitate the proximal aortic anastomosis. Regional oxygen saturation in the bilateral frontal lobes was measured intraoperatively using near-infrared spectroscopy to detect cerebral ischemia. Regional oxygen saturation was managed above the critical level throughout the CPB. No new cerebral complications occurred in the perioperative period.

Aortic Coarctation↗