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Biomedical subjects

Y Yonekawa

Publications and source records attributed to Y Yonekawa.

At least 37 records · Page 2Linked to original sources
PubMed2005

Kyoto islet isolation method: the optimized one for non-heart-beating donors with highly efficient islet retrieval.

The availability of pancreata for clinical cadaveric islet transplantation is restricted to non-heart-beating donors (NHBDs) in Japan. This forced us to modify the current standard islet isolation protocol that was made up for brain-dead donors and make it suitable for NHBDs. The Kyoto islet isolation method is the one with induction of several steps based on the ideas both already reported literally and invented originally by ourselves. Using this islet isolation method, we isolated islets from 13 human pancreata of NHBDs and transplanted 11 preparations to six type-1 diabetic patients. The rate to meet release criteria of Edmonton protocol was 84.6%. Establishment of this method allowed us to begin a clinical islet transplantation program in Japan and to continue to perform the preparation of islets from NHBDs with high rate to meet the release criteria of the Edmonton protocol.

Brain Death↗
PubMed2004

Seasonal variations in hospital admissions due to aneurysmal subarachnoid haemorrhage in the state of Zurich, Switzerland.

INTRODUCTION: In clinical practice, the occurrence of aneurysmal subarachnoid haemorrhage (SAH) often coincides with a particular season. Our objective was to examine seasonal variations in hospital admissions due to aneurysmal SAH. METHODS: The study population consisted of 489 patients with aneurysmal SAH who were admitted to the Department of Neurosurgery, University Hospital of Zurich, Switzerland, between 1st of January 1996 and 31st of December 2002. Statistical significance of seasonal variation was determined by applying Roger's r test. RESULTS: Statistically significant seasonal variation was only found among patients younger than 60 years, showing a first peak in spring and second lower peak in autumn (Roger's r=6.89, p<0.05). A borderline significance was found in men younger than 60 years (Roger's r=5.96, p=0.051). A trend was observed in patients presenting with Fisher grade 1-2 (Roger's r=5.70, p=0.058). CONCLUSIONS: Previous studies from different countries have shown significant seasonal variations, with the peak period for aneurysmal SAH differing widely. There appears to be some link between aneurysmal SAH and the season of the year or variations in weather conditions. Further investigations are desirable to evaluate which weather or climatic parameters correlate well with SAH.

Adult↗
PubMed2003

A new subdural probe for combined intracranial pressure (ICP) and cerebral blood flow (CBF) monitoring.

We report the development of a new subdural probe for combined intracranial pressure (ICP) and cerebral blood flow (CBF) monitoring with near infrared spectroscopy (NIRS) and indocyanine green (ICG) dye dilution. For NIRS a conventional subdural ICP monitoring probe was supplied with two fiber bundles and 90-degree prisms. Injections of 25 mg ICG were performed. Regional values for the mean transit time of ICG (rmtt(ICG)), cerebral blood flow (rCBF) and cerebral blood volume (rCBV) were calculated. With prototypes of the probe in two patients with intracerebral haemorrhage 18 comparative measurements obtained simultaneously with conventional NIRS (optodes placed on the skin) and the subdural NIRS probe were performed. The new subdural NIRS probe allows combined monitoring of ICP and cerebral hemodynamics in the brain directly, without the influence of extracerebral tissue.

Blood Flow Velocity↗
PubMed2003

Moyamoya disease and Moyamoya syndrome: experience in Europe; choice of revascularisation procedures.

OBJECTIVES: To present our clinical experience in terms of disease presentation and choice of revascularisation procedure in our first group of 23 European Moyamoya angiopathy (disease and syndrome) patients. METHOD AND PATIENT SELECTION: Twenty three patients were diagnosed and treated from 1997-2001 in our neurosurgical department. All patients underwent preoperative angiography, colour Doppler examination, cranial MRI and/or CT scans, HMPAO-SPECT or H(2)(15)O PET (baseline and Diamox challenge) scans. Nineteen patients presented with child-juvenile Moyamoya angiopathy with an average age at presentation of 8 years (range 1-17 years), in 4 patients adult Moyamoya was diagnosed with a mean age at presentation of 34 years (range 23-40 years). RESULTS: In all but one patient bilateral affection was present at the time of diagnosis. All patients underwent direct and/or additional indirect revascularisation procedures. Twenty-one patients underwent bilateral revascularisation procedures. In two patients a unilateral procedure was performed. A direct STA-MCA bypass (superficial temporal artery branch - middle cerebral artery branch anastomosis) was performed in all patients. Additional direct STA-ACA bypass (STA - anterior cerebral artery branch anastomosis) was performed in 10 patients. Indirect arteriosynangiosis using the occipital artery was performed in the posterior cerebral artery (PCA) territory in 3 patients. The frontal branch of the STA was used for arteriosynangiosis in the frontal region in another 2 patients. Indirect frontal durasynangiosis was performed in 14 patients. The number and location of multiple revascularisation procedures was determined according to the angiographic findings as well as the site of decreased perfusion reserves seen on H(2)(15)O PET. A one stage revascularisation procedure was performed in 7 patients. Fourteen patients underwent two stage procedures. Following operation no complications were encountered in all but one adult patient who died postoperatively due to a massive middle cerebral artery infarct on the nonoperated side. CONCLUSIONS: As territorial hemodynamic disorder seems to be a characteristic in Moyamoya disease and/or syndrome, judging from our experience with European patients in our series, and several reports hitherto, treatment with multiple revascularisation procedures is considered to be justified.

Adolescent↗
PubMed2002

Intensive care management of patients with severe intracerebral haemorrhage after endovascular treatment of brain arteriovenous malformations.

We studied the impact of emergency neurosurgery and intensive care on the outcome for patients with severe intracerebral haemorrhage after endovascular treatment of brain arteriovenous malformations (AVMs). We reviewed the case notes of 18 patients with severe haemorrhage after embolisation of a brain AVM between 1986 and 2001. During this period the treatment changed: before 1993, these patients were not surgically treated, and they died, while after 1994, all patients underwent emergency surgery. We established a standardised protocol for emergency treatment and intensive care in May 1998, and emergency surgery was performed as soon as possible after the onset of symptoms of haemorrhage. Postoperative intensive care was according to a standardised regime. During these 15 years, 24 out of 605 patients undergoing 1066 interventions had a haemorrhage during or after the procedure, of which 18 were severe (3% of patients, 1.7% of interventions). All patients had a severe clinical deficit (mean Glasgow coma scale 4.2); eight had uni- or bilateral mydriasis. From 1989 to April 1998 four (31%) of 13 patients died, one (7.5%) remained in a vegetative state and eight (61.5%) made a good recovery. All five patients treated between 1998 and 2001 had a favourable outcome. The mean time from onset of the symptoms of haemorrhage to reaching the operation room was 129 min between 1989 and 1998 and 24 min between 1998 and 2001. Standardised emergency treatment and intensive care with early resuscitation, minimal radiological exploration before rapid surgery improved the outcome. A short time between the onset of the symptoms of haemorrhage and evacuation of the haematoma may be the most important factor for a favourable outcome.

Adult↗
PubMed2002

Dynamic changes during evacuation of a left temporal abscess in open MRI: technical case report.

We demonstrate the usefulness of "near real-time" neuro-navigation by open MRI systems for guidance of stereotactic evacuation of intracranial abscesses. A 70-year-old patient was referred to our institution with an intracranial left temporal abscess. He presented with headache, senso-motor aphasia and mild right hemiparesis. The abscess (35 x 25 mm) was stereotactically evacuated under MRI guidance, and a recurrence of a daughter abscess was again evacuated on the 9th postoperative day. "Near real-time" imaging showed an indentation of the abscess wall of 11 mm along the trajectory. A thermosensitive MRI protocol demonstrated a higher temperature around the abscess capsule than in the brain tissue more distant to the capsule, demonstrating the inflammatory process. The patient had 6 weeks of antibiotic therapy for gram-negative bacteria and was discharged with improved clinical symptoms 5 weeks after admission. Follow-up CT 2 months postoperatively showed a complete resolution of the abscess. Open MRI-guided interventions with "near real-time" imaging demonstrate the anatomical changes during an ongoing procedure and can be accommodated for enhancing the overall precision of stereotactic procedures. Thermosensitive MRI protocols are capable of revealing temperature gradients around inflammatory processes.

Aged↗
PubMed2002

Presentation and management of patients with initial negative 4-vessel cerebral angiography in subarachnoid hemorrhage.

The importance of repeat-angiography in patients with acute subarachnoid hemorrhage (SAH) and initial negative angiography has been reviewed in the light of our patient population (19 patients with initial negative angiography/168 patients with SAH). The type of SAH i.e., nontraumatic perimesencephalic SAH versus focal or generalized non perimesencephalic SAH, as well as the amount and distribution of blood on the initial CT examination are important factors in decision making. 3D-Angio-CT, in 3/5 patients, and MR-angiography (MRA) in 1/5 patients were complementary non-invasive methods to diagnose aneurysms on repeated examinations. Repeat-cerebral angiography confirmed the source of hemorrhage in 3 patients.

Adult↗
PubMed2002

Neurological and neuropsychological outcome after SAH.

The fact that neurological status and physical integrity alone do not sufficiently assess the overall state of patients after aneurysmal subarachnoid hemorrhage (SAH) gives rise to the necessity for complementary neuropsychological investigation. Neuropsychological work-up should also cover an emotional state, psychosocial adjustment and competence in everyday life of the patients. In our prospective study we investigated 82 patients three months and one year after SAH and early clipping of the aneurysm. For the evaluation of postoperative neurological functions the Glasgow Outcome Scale (GOS) was used. For the neuropsychological assessment we used standardized measures of verbal and figural learning and memory, verbal and figural fluency, speed of information processing, visuospacial abilities and affective function. One year after SAH 95.6% of patients with Hunt&Hess Grade 1 and 2 on admission showed good neurological results (GOS 4 and 5). However, only 30.1% (18 of 63 patients with a favourable neurological outcome--GOS 4 and 5) did not show any neuropsychological deficit. Localization of the ruptured aneurysm significantly correlated with cognitive measures. The best cognitive outcome was shown in patients with aneurysms on the anterior communicating artery (ACoA) followed by posterior communicating artery (PCoA) and those located on the internal carotid artery (ICA) on the right side.

Aneurysm, Ruptured↗
PubMed2002

New methods for monitoring cerebral oxygenation and hemodynamics in patients with subarachnoid hemorrhage.

Radiographic cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH) do not reflect cerebral hemodynamics and oxygenation and may occur in the absence of clinical deficit and vice-versa. This report is to describe preliminary findings in further development of a non invasive method to estimate regional cerebral oxygenation and perfusion. Measurements were performed with a technique combining near infrared spectroscopy (NIRS) and indocyaningreen (ICG) dye dilution. Successful data analysis has been performed based on the decomposition in pulsatile and non-pulsatile components of NIRS absorption data collected before and during the passage of ICG through the vascular bed under the NIRS-detector. First measurements in patients with CVS suggest that the technique could become a powerful tool in the detection and treatment of CVS. This non invasive technique can be done at the bedside, it seems to be safe, easy to perform and less time-consuming compared to conventional techniques. The influence of extracerebral bone and surface tissue on cerebral NIRS signal has not been clarified yet. Therefore a new subdural NIRS probe has been developed, which gives the opportunity to measure directly the concentration of the chromophores in the brain without the influence of extracerebral contamination. In future comparative measurements with conventional NIRS probes on the scalp will allow to quantify and eliminate extracerebral contamination from the NIRS signal.

Adult↗
PubMed2002

Strategies for surgical management of cerebral aneurysms of special location, size and form--approach, technique and monitoring.

Special strategies are mandatory for optimal surgical management of aneurysms of special location, size and form. Approaches of extradural selective anterior clinoidectomy, partial occipital condylectomy, transpetrosal approach by anterior petrosectomy and supracerebellar transtentorial approach are discussed among them. Furthermore various types of temporary and permanent clipping procedures are discussed along with mention of intraoperative monitoring.

Craniotomy↗
PubMed2002

Surgical prognosis of unruptured cerebral aneurysms. Report of 40 cases in University Hospital Zurich.

A series of 40 patients admitted to University Hospital Zurich (1996-97) with unruptured cerebral aneurysms is reported. Fifty-two aneurysms were treated in 40 operations. The age of surgically treated patients ranged from 31 to 78 year old (mean 53.6). The main locations of the aneurysms were: MCA 21 (40.4%), AcomA 10 (19.2%), ICA (posterior communicating and bifurcation) 6 (11.5%), carotid-ophthalmic segment 4 (7.7%), ACA 4 (7.7%), basilar tip 3 (5.8%), vertebral artery 2 (3.8%). The circumstances of diagnosis were: incidental 15 (37.5%), other cranial lesions 9 (22.5%), symptomatic 8 (20%), multiple aneurysm 8 (20%). The overall outcome of surgery was: good recovery in 39 cases (97.5%), moderately disabled in 1 case (2.5%) who was 56 year-old and had three aneurysms including basilar tip. There was no operative mortality. Though this series has small number of patients, it suggests that location of the aneurysm is an important factor affecting surgical outcome among patient age, the circumstances of the diagnosis, size and location of aneurysm.

Adult↗
PubMed2002

Thermotactile threshold testing for the evaluation of sensory nerve function in vibration-exposed patients and workers.

OBJECTIVES: The aim of the present study was to ascertain the usefulness of thermotactile testing under the measuring conditions clarified by our previous study in the evaluation of vibration-induced neuropathy. METHOD: Thermal (warm and cold) thresholds were examined on the index fingers of both hands of ten patients with hand-arm vibration syndrome, 36 workers exposed to hand-transmitted vibration, and ten healthy controls, using an aesthesiometer under the following measuring conditions: change rate of the applicator temperature was fixed at a rate of 1 degrees C/s; finger contact force on the applicator was kept at 0.5 N; and forearm was positioned on a support. Vibrotactile thresholds at 125 Hz and pain thresholds were also measured on the index fingers. RESULTS: Both warm and cold thresholds had more severely deteriorated in the patients than in the controls. Vibrotactile and pain thresholds were also increased in the patients. In the vibration-exposed workers, the neutral zone between the warm and cold threshold differed from in the controls. Thermotactile thresholds were likely to have deteriorated with advanced nerve impairment. Likelihood ratios of thermotactile testing were significantly high between the patients and the controls. For vibration-exposed workers with elevated vibrotactile and pain thresholds, the ratios were also significantly high, particularly in the neutral zone, though the accuracy tended to be lower than in the patients. Thermotactile thresholds appeared to be more closely correlated with pain thresholds than vibrotactile thresholds. CONCLUSIONS: Thermotactile threshold testing under the present measuring conditions can be useful for evaluating small sensory nerve fibre dysfunction in vibration-exposed subjects, and the neutral zone may be a sensitive indicator in vibration-exposed workers who may have slight or mild nerve impairments.

Adult↗
PubMed2001

Germline SDHD mutation in paraganglioma of the spinal cord.

Hereditary paraganglioma of the head and neck is associated with germline mutations in the SDHD gene, which encodes a mitochondrial respiratory chain protein. Paragangliomas of the central nervous system are very rare, occur almost exclusively in the cauda equina of the spinal cord and are considered non-familial. In the present study, we screened 22 apparently sporadic paragangliomas of the cauda equina for SDHD mutations. One spinal paraganglioma and similar cerebellar tumours that developed 22 years later in the same patient contained a missense mutation at codon 12 (GGT-->AGT, Gly-->Ser) and a silent mutation at codon 68 (AGC-->AGT, Ser-->Ser). There was no family history of paragangliomas but DNA from white blood cells of this patient showed the same sequence alterations, indicating the presence of a germline mutation. All other cases of spinal paraganglioma had the wild-type SDHD sequence, except one case with a silent mutation at codon 68 (AGC-->AGT, Ser-->Ser). This is the first observation indicating that inherited SDHD mutations may occasionally cause the development of paragangliomas in the central nervous system.

Cauda Equina↗
PubMed2001

Stroke in hemoglobin (SD) sickle cell disease with moyamoya: successful hydroxyurea treatment after cerebrovascular bypass surgery.

An 11-year-old boy with hemoglobin sickle disease (HbSD), bilateral stenosis of the intracranial carotid arteries, and moyamoya syndrome had recurrent ischemic strokes with aphasia and right hemiparesis. His parents (Jehovah's Witnesses) refused blood transfusions. After bilateral extracranial-intracranial (EC-IC) bypass surgery, hydroxyurea treatment increased hemoglobin F (HbF) levels to more than 30%. During a follow-up of 28 months, flow velocities in the basal cerebral arteries remained stable, neurologic sequelae regressed, and ischemic events did not recur. This is the first report of successful hydroxyurea treatment after bypass surgery for intracranial cerebral artery obstruction with moyamoya syndrome in sickle cell disease. The patient's religious background contributed to an ethically challenging therapeutic task. (Blood. 2001;97:2165-2167)

Anemia, Sickle Cell↗
PubMed2001

Severe arterial occlusive disorder and brachysyndactyly in a boy: a further case of Grange syndrome?

We report on a 15-year-old boy with stenosis and occlusion of multiple cranial, renal, and celiac arteries, aneurysm of the basilar artery, bilateral cutaneous syndactyly between fingers IV-V, partial cutaneous syndactyly between fingers III-IV on the right hand, brachydactyly, and borderline mental retardation. The clinical course was characterized by recurrent abdominal pain, gastritis, and high blood pressure. The pattern of the clinical and radiological findings is different from fibromuscular dysplasia (FMD) and Moyamoya disease, and highly suggestive of a syndrome described by Grange in four siblings (MIM#602531) Grange et al. [1998: Am J Med Genet 75: 469-480].

Abnormalities, Multiple↗