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Biomedical subjects

T Kawase

Publications and source records attributed to T Kawase.

At least 55 records · Page 3Linked to original sources
PubMed2001

Evaluation of ppk-specified polyphosphate as a mercury remedial tool.

To evaluate the utility of polyphosphate kinase gene (ppk)-specified polyphosphate in mercury remediation, a fusion plasmid, pMK27, with ppk from Klebsiella aerogenes and mercury transport genes, merT and merP, from Pseudomonas K-62, was constructed. The transcription and translation of ppk, merT and merP were found to be mercury-inducible. The ppk-specified polyphosphate was identified in cells preinduced by Hg2+, but not in cells without mercury induction, suggesting that the synthesis of polyphosphate is regulated by merR. The hypersensitive phenotype to Hg2+, shown by bacteria with pMRD141, which contains merT and merP, was almost completely restored to its original levels when the ppk was introduced into the plasmid, suggesting that the Hg2+-toxicity was reduced by the polyphosphate, probably via chelation formation. Bacteria with pMK27 accumulated approximately 6-fold more mercury than the bacteria with cloning vector, pUC119. These results clearly demonstrate that the polyphosphate is capable of retaining mercury in the cells without taxing the cells. Based on the results obtained in the present study, the fusion plasmid pMK27 may serve as a strategy for mercury remediation.

Bacterial Proteins↗
PubMed2001

Spontaneous thrombosis of intracavernous internal carotid artery aneurysm and parent artery occlusion in patients with positive balloon test occlusion--two case reports.

Two patients with giant intracavernous internal carotid artery (ICA) aneurysms were intolerant to balloon test occlusion of the ICA, and later developed spontaneous thrombosis of the aneurysm and the parent ICA without ischemic sequelae. Case 1: A 60-year-old female with a giant right intracavernous ICA aneurysm presented with right abducens nerve paresis. An unsuccessful extracranial-to-intracranial bypass graft operation was complicated by transient postoperative ophthalmoplegia. The patient did not tolerate balloon test occlusion of the right ICA after attempted bypass surgery, and was treated conservatively. The patient presented with acute onset of headache 3 years later. Case 2: A 50-year-old female with a giant right intracavernous ICA aneurysm presented with right abducens nerve paresis. The patient was managed conservatively after a positive balloon test occlusion of the right ICA. The patient suffered transient hypopituitarism and acute onset of headache 2 years later. Spontaneous thrombosis of the aneurysms and occlusion of the parent ICA were found in both patients. Neither had major hemispheric infarcts, but the first patient had asymptomatic infarcts, which were presumed to be thromboembolic in nature. Patients with intracavernous ICA aneurysms who have positive balloon test occlusions appear to develop tolerance to spontaneous and gradual occlusion of the ICA without significant sequelae. However, these patients have an increased risk of developing embolic infarctions. The role for anticoagulation and repeat hemodynamic tests remains unclear.

Balloon Occlusion↗
PubMed2001

Isolated abducens nerve paresis associated with incomplete Horner's syndrome caused by petrous apex fracture--case report and anatomical study.

A 17-year-old male presented with a wound on the right temporal region, oozing hemorrhagic necrotic brain tissue and cerebrospinal fluid, following a fall. Computed tomography showed temporoparietal and petrous apex fractures on the right. Neurological examination revealed abducens nerve paresis, ptosis, and myosis on the right side. The patient was treated surgically for the removal of the free bony fragments at the fracture site and to close the dural tear. The abducens nerve paresis, ptosis, and myosis persisted at the 3rd monthly postoperative follow-up examination. The anatomy of the abducens nerve at the petroclival region was studied in four cadaveric heads. Two silicone-injected heads were used for microsurgical dissections and two for histological sections. The abducens nerve has three different angulations in the petroclival region, located at the dural entrance porus, the petrous apex, and the lateral wall of the cavernous segment of the internal carotid artery. The abducens nerve had fine anastomoses with the trigeminal nerve and the periarterial sympathetic plexus. There were fibrous connections extending inside the venous space of the petroclival area. The abducens nerve seems to be vulnerable to damage in the petroclival region, either directly by trauma to its dural porus and petrous apex or indirectly by stretching of the nerve through the nervous and/or fibrous connections. Concurrent functional loss of the abducens nerve and the periarterial sympathetic plexus clinically manifested as incomplete Horner's syndrome in our patient.

Abducens Nerve↗
PubMed2001

[Biodistribution of hypoxic marker, 99mTc-HL91 (4,9-diaza-3,3,10,10-tetramethyldodecan-2,11-dione dioxime)].

99mTc-HL91 (4,9-diaza-3,3,10,10-tetramethyldodecan-2,11-dione dioxime) was developed as a hypoxic marker. Athymic mice bearing human tumors were administered with 99mTc-HL91 to evaluate it from the clinical point view. The tumor was visualized clearly 4 hours after injection. The biodistribution study revealed that 99mTc-HL91 was accumulated in the liver (tissue-to-blood ratio (T/B) = 11.5) and kidney (2.25) with higher than in the tumor (1.01). Oxygen condition of the tumor and muscle was measured by using the probe. 99mTc-HL91 uptake of tumors with PO2 (tumor-to-muscle ratio) under 0.55 was higher than that with 0.55 or higher PO2. Oxygen condition of tumors with 1.0 or higher uptake (tumor-to-blood ratio) was lower than that with the lower uptake. Autoradiography of tumor sections indicated that 99mTc-HL91 was scarcely accumulated in the necrotic and viable areas while strong radioactivity was observed in the border zone (speculated to be hypoxic condition). Our experimental results suggest that the 99mTc-HL91 scintigraphy may be useful for evaluating oxygenation status of some tumors in non-abdominal region.

Animals↗
PubMed2000

High-resolution inkjet printing of all-polymer transistor circuits.

Direct printing of functional electronic materials may provide a new route to low-cost fabrication of integrated circuits. However, to be useful it must allow continuous manufacturing of all circuit components by successive solution deposition and printing steps in the same environment. We demonstrate direct inkjet printing of complete transistor circuits, including via-hole interconnections based on solution-processed polymer conductors, insulators, and self-organizing semiconductors. We show that the use of substrate surface energy patterning to direct the flow of water-based conducting polymer inkjet droplets enables high-resolution definition of practical channel lengths of 5 micrometers. High mobilities of 0.02 square centimeters per volt second and on-off current switching ratios of 10(5) were achieved.

Journal Article↗
PubMed2000

Post-ischemic hypothermia delayed neutrophil accumulation and microglial activation following transient focal ischemia in rats.

Following ischemia, inflammation has been demonstrated to be involved in the progression of the tissue damage. Intra-ischemic hypothermia has been shown to attenuate the adverse activities of neutrophils and microglia. We investigated whether neutrophil accumulation and/or microglial activation is attenuated in post-ischemic hypothermia following transient focal ischemia in rats. After 1 h of ischemia, the neutrophil accumulation and the microglial activation was evaluated immunohistochemically. Percent infarct area was compared at 1, 2, 3, 5, and 7 days after ischemia/reperfusion. In hypothermia, the neutrophil accumulation was delayed but not attenuated. In normothermia, the accumulation reached the peak at 2 days after ischemia. The peak shifted to 3 days in hypothermia. Similarly, the microglial activation was delayed in hypothermia. Comparison of the infarct area showed significant protection by hypothermia at 1 and 2 days after reperfusion. However, hypothermia failed to show significant protection after 3 days and later. These results show that the delayed neutrophil accumulation and the microglial activation can be responsible for the loss of persistent protection in post-ischemic hypothermia.

Animals↗
PubMed2000

The modified tangential irradiation technique for breast cancer: how to cover the entire axillary region.

PURPOSE: The two-portal tangential irradiation technique has usually been applied to breast cancer patients after breast-conserving surgery (1, 2) and is expected to irradiate the axillary lymph node region to some extent (3). We investigated the range of the axillary region covered by this technique and tried to devise an optimal irradiation technique (modified tangential irradiation) that would cover the axillary lymph node region properly. METHODS AND MATERIALS: We checked the status of the surgical clips left at axillary lymph node sites by reviewing the simulator films and planning CT scans of 63 patients who underwent axillary dissection of level I, I-II, or I-III lymph nodes. Then we created the modified tangential irradiation technique and applied this technique to 16 patients and checked the irradiation volume by CT scans. RESULTS: We found that all of the surgical clips on lateral-view simulator films were on the ventral side of the dorsal edge line of the humeral head. All but one clip were on the caudal side of the caudal edge line of the humeral head. Accordingly, it is possible to irradiate almost all axillary lymph node regions by setting the dorsal edge of the irradiation field on lateral-view simulator films at the dorsal edge of the humeral head and the cranial edge at the caudal edge of the humeral head. CONCLUSIONS: All breast tissue and the entire axillary lymph node region can be covered by the modified tangential irradiation technique without increasing the lung volume irradiated.

Adult↗
PubMed2000

Novel mutations in the connexin 26 gene (GJB2) responsible for childhood deafness in the Japanese population.

Mutations in the connexin 26 gene (GJB2), which encodes a gap-junction protein and is expressed in the inner ear, have been shown to be responsible for a major part of nonsyndromic hereditary prelingual (early-childhood) deafness in Caucasians. We have sequenced the GJB2 gene in 39 Japanese patients with prelingual deafness (group 1), 39 Japanese patients with postlingual progressive sensorineural hearing loss (group 2), and 63 Japanese individuals with normal hearing (group 3). Three novel mutations were identified in group 1: a single nucleotide deletion (235delC), a 16-bp deletion (176-191 del (16)), and a nonsense mutation (Y136X) in five unrelated patients. The 235delC mutation was most frequently observed, accounting for seven alleles in 10 mutant alleles. Screening of 203 unrelated normal individuals for the three mutations indicated that the carrier frequency of the 235delC mutation was 2/203 in the Japanese population. No mutation was found in group-2 patients. We also identified two novel polymorphisms (E114G and I203T) as well as two previously reported polymorphisms (V27I andV37I). Genotyping with these four polymorphisms allowed normal Japanese alleles to be classified into seven haplotypes. All 235delC mutant alleles identified in four patients resided only on haplotype type 1. These findings indicate that GJB2 mutations are also responsible for prelingual deafness in Japan.

Adolescent↗
PubMed2000

Postischemic hypothermia attenuates apoptotic cell death in transient focal ischemia in rats.

Hypothermia confers potent neuroprotection against ischemic injury. Attenuation of apoptosis by hypothermia can be one of the responsible mechanisms. In this study, in situ DNA nick-end labeling (TUNEL) and immunostaining of Bax protein were performed to evaluate the effect of postischemic hypothermia on apoptotic cell death, employing rodent transient focal ischemia. Animals received 1 hour of transient focal ischemia. Brain temperature was maintained at 37.5 +/- 0.5 degrees C during ischemia. Immediately after reperfusion, animals were assigned to either a normothermic or hypothermic group. In hypothermia, animals were cooled and brain temperature was lowered to 34.5 +/- 1.0 degrees C. Prolonged hypothermia was maintained for 16 hours and animals rewarmed. In both groups, TUNEL and immunostaining of Bax was performed. In normothermia, the number of TUNEL positive cells reached the peak at 2 days after ischemia and decreased gradually. In hypothermia, the peak was shifted to 3 days after ischemia. The number of TUNEL positive cells in hypothermia was persistently below that of normothermia. Similarly, in hypothermia, immunostaining of Bax showed attenuated immunoreactivity compared with that in normothermia. In conclusion, postischemic hypothermia reduced both the number of TUNEL positive cells and immunoreactivity of Bax, which may be one of the responsible mechanisms with which hypothermia exerts neuroprotection.

Animals↗
PubMed2000

Analyses of proliferative potential in schwannomas.

We report studies of schwannomas with a high percentage of MIB-1 positive cells. Thirty-eight specimens from 36 cases of schwannoma in the intracranial and spinal regions comprise the substance of this study. The MIB-1 positive cells were measured using immunohistochemical staining. In nine cases with a positivity index (PI) of 5% or more, immunohistochemical staining using DNA topoisomerase IIalpha (topo-II) and CD68 was performed. In some cases, we also searched for apoptosis with the TdT-mediated dUTP-biotin nick-end labeling (TUNEL) method. Three of nine cases with 5% or more positive MIB-1 cells had a very high cellularity with mitotic figures and were considered cellular Schwannomas. Their MIB-1 PI values were 8.21%, 10.00%, and 21.37%. However, the remaining six cases showed little evidence of malignancy. Their PIs were comparatively low, ranging from 5.19% to 8.41%, and the positive findings were localized in many cases. In these cases, we examined the sites where MIB-1 was measured and found that they corresponded to the borderline site between Antoni type A and B patterns and tended to be associated with an infiltration of CD68-positive macrophage. Furthermore, apoptotic cells appeared in the sites. With topo-II staining, the PIs in the same sites of these six cases were low, ranging from 0.78% to 1.93%. This implies that the high MIB-1 PI that was seen in these six cases was caused by reaction of MIB-1 to tumor cells that brought about an abnormality in the cell cycle by degeneration, such as apoptosis. In the site of formation of Antoni type B, MIB-1 may be a false positive in tumors with degenerative findings such as schwannomas. Topo-II was useful in these cases.

Adult↗
PubMed2000

Impairment of spatial memory and changes in astroglial responsiveness following loss of molar teeth in aged SAMP8 mice.

In order to evaluate the mechanism(s) responsible for senile impairment of cognitive function as a result of reduced mastication, the effects of the loss of the molar teeth (molarless condition) on the hippocampal expression of glial fibrous acidic protein (GFAP) and on spatial memory in young adult and aged SAMP8 mice were studied using immunohistochemical and behavioral techniques. Aged molarless mice showed a significantly reduced learning ability in a water maze test compared with age-matched control mice, while there was no difference between control and molarless young adult mice. Immunohistochemical analysis showed that the molarless condition enhanced the age-dependent increase in the density and hypertrophy of GFAP-labeled astrocytes in the CA1 region of the hippocampus. These effects increased the longer the molarless condition persisted. When the extracellular K+ concentration ([K+]o) was increased from 4 to 40 mM for hippocampal slices in vitro, the mean increase in the membrane potential was about 57 mV for fine, delicate astrocytes, the most frequently observed type of GFAP-positive cell in the young adult mice, and about 44 mV for the hypertrophic astrocytes of aged mice. However, there was no significant difference in resting membrane potential between these cell types. The data suggest that an impairment of spatial memory and changes in astroglial responsiveness occur following the loss of molar teeth in aged SAMP8 mice.

Aging↗
PubMed2000

Long-term outcome of 17 cases of large-giant posterior fossa aneurysm.

Long-term outcome of 17 patients who harbored a large or giant aneurysm of posterior fossa was summarized. The anatomical distribution of aneurysms included eight cases of basilar artery (BA) bifurcation aneurysms, three cases of BA trunk aneurysms, and six cases of vertebral artery (VA) aneurysms. Eight patients received surgical or endovascular treatment for their lesion. The clinical outcome was good recovery in six, moderate disability in one, and vegetative state in one case, respectively. The other nine patients were followed conservatively. Four of them had fatal aneurysmal rupture, and another two patients suffered from aggravation of pre-existing symptoms related to their aneurysm. Only three patients remain intact. Comparison of the radiographic parameters between those who bled and those who did not bleed revealed that those with subsequent rupture had significantly higher rate of aneurysmal thrombus and had a trend for larger diameter of the aneurysm. Although more aggressive and multidisciplinary measure should be taken to these patients to improve their long-term outcome, our results showed the limitation of treatment for these patients in the present era at the same time. The patients with broad neck BA bifurcation aneurysm in which efferent vessels were incorporated into aneurysmal dome, and those with fusiform, giant BA trunk aneurysm with thrombus were the least amenable to treatment in our series.

Adult↗
PubMed2000

Basilar artery occlusion due to mucormycotic emboli, preceded by acute hydrocephalus.

A rare case of brain stem infarction caused by mucormycotic emboli, preceded by acute hydrocephalus, is reported. The patient, who had suffered from leukemia and had undergone bone marrow transplantation several months before, presented initially with seizure and persistent disturbance of consciousness. A head CT scan revealed marked ventricular dilation and diagnosed as acute hydrocephalus. The patient received emergent ventricular drainage. Despite the aggressive treatment, the patient did not survive. Autopsy revealed systemic mucormycosis occluding and invading various arteries including basilar artery and its branches, causing fatal brainstem infarction. Although early diagnosis remains difficult in the cases of systemic mucormycosis, prompt initiation of treatment is mandatory; one must have in mind the possibility of presence of fungal infection when treating patients with acute neurological deterioration who have underlying debilitating diseases, even though fungi themselves are hard to detect in most cases.

Acute Disease↗
PubMed2000

Effects of contralateral noise on measurement of the psychophysical tuning curve.

The effects of the addition of contralateral noise on the psychophysical tuning curve (PTC) were examined in subjects with normal hearing. The masking threshold of the tail part of the PTC tended to decrease with the addition of contralateral noise, although the threshold reduction was usually less than 5 dB. On the other hand, the effects of contralateral noise were relatively small around the tip of the PTC contour. Focusing on the effects of contralateral noise on the masking threshold at the tail part of the PTC, the effects of changing the time between initiation of masking the tone and the presentation of the masked probe tone on the threshold reduction at the tail part of the PTC were also observed. The results indicate that the reduction of the masking threshold by the addition of contralateral noise tended to be larger when the presentation of the signal tone was delayed after the onset of the masker. Usually, when the signal tone was presented under conditions of the forward masking paradigm, the reduction of the threshold was most remarkable. Results obtained in the present study are discussed based on the known characteristics of the olivocochlear (OC)-efferent fibers activated by contralateral noise.

Adult↗
PubMed2000

Measurement of stapedius contraction during vocalization effort in patients after laryngectomy or tracheostomy.

The contraction of the stapedius muscle during the effort of vocalization was examined by measurement of acoustic compliance in subjects who had undergone laryngectomy or tracheostomy. No significant level of persistent compliance change was recorded in any of the subjects, indicating the absence of effective contraction of the stapedius during the vocalization effort. In two subjects who use an electrolarynx, although no significant compliance change resulted from the simple vocalization effort without the electrolarynx (no actual vocalized sound), a remarkable level of persistent compliance change was observed during the vocalization using the electrolarynx. These results seem to indicate that a simple vocalization effort without actual voice cannot elicit effective contraction of the middle ear muscles, and that sound generation during vocalization is essential for effective contraction of the middle ear muscles during vocalization, at least in some human subjects.

Aged↗