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Biomedical subjects

Y Tada

Publications and source records attributed to Y Tada.

At least 235 records · Page 13Linked to original sources
PubMed1994

Acute bilateral cerebellar infarction in the territory of the medial branches of posterior inferior cerebellar arteries.

BACKGROUND: We describe the first clinicoradiological report of acute bilateral cerebellar infarction confined to the territory of the medial branches of the posterior inferior cerebellar arteries. CASE DESCRIPTION: A 65-year-old man with atrial fibrillation and hypertension had sudden onset of vertigo, followed by brief loss of consciousness. Three days later a cranial computed tomographic scan showed acute hydrocephalus and low-density areas in the cerebellar vermis on both sides. On transfer the patient showed mild dysarthria, dysequilibrium with retropulsion, symmetrical bilateral horizontal gaze-evoked nystagmus on lateral gaze, and marked gait ataxia without brain stem signs, followed by marked vertigo that was induced by motion. Cranial magnetic resonance imaging revealed abnormalities consistent with fairly symmetrical bilateral cerebellar hemorrhagic infarction that was confined to the territory of the medial branches of the posterior inferior cerebellar arteries, in addition to minimal high-intensity areas in the pons on T2-weighted images. The patient improved with conservative therapy, including intravenous administration of glycerol. CONCLUSIONS: We speculate that our patient likely had initial transient occlusion of the right vertebral artery at the origin of the right posterior inferior cerebellar artery, which probably gave rise to the bilateral medial branches of posterior inferior cerebellar arteries. This caused infarction in the territory of the medial branches on both sides without remaining brain stem signs. Such an unusual pattern of cerebellar infarction accompanied by acute hydrocephalus posed a diagnostic challenge at the time of transfer to our care, and correct diagnosis was facilitated by cranial magnetic resonance imaging.

Aged↗
PubMed1994

Perforin-secreting killer cell infiltration and expression of a 65-kD heat-shock protein in aortic tissue of patients with Takayasu's arteritis.

Cell-mediated autoimmunity has been strongly implicated in the pathogenesis of vascular cell injury in Takayasu's arteritis. To clarify the immunological mechanisms involved, we examined the expression of a cytolytic factor, perforin in infiltrating cells of aortic tissue samples from seven patients with Takayasu's arteritis. We also examined the expression of a 65-kD heat-shock protein (HSP-65), human leukocyte antigen classes I and II, and intercellular adhesion molecule-1 in the aortic tissue. Immunohistochemical studies showed that the infiltrating cells mainly consisted of gamma delta T lymphocytes, natural killer cells, macrophages, cytotoxic T lymphocytes and T helper cells, and that perforin was expressed in gamma delta T lymphocytes, natural killer cells, and cytotoxic T lymphocytes. In situ hybridization analysis also revealed expression of perforin mRNA in the infiltrating cells. Immunoelectron microscopic studies demonstrated that the infiltrating cells released massive amounts of perforin directly onto the surface of arterial vascular cells. We also found that expression of HSP-65, human leukocyte antigen classes I and II, and intercellular adhesion molecule-1 was strongly induced in the aortic tissue and might facilitate the recognition, adhesion and cytotoxicity of the infiltrating killer lymphocytes. These findings provide the first direct evidence that the infiltrating cells in the aortic tissue mainly consist of killer cells, and strongly suggest that these killer cells, especially gamma delta T lymphocytes, may recognize HSP-65 and play a critical role in the vascular cell injury of Takayasu's arteritis by releasing perforin.

Adult↗
PubMed1994

Giant thrombosed vertebral artery aneurysm treated by extracranial-intracranial bypass and aneurysmectomy--case report.

A 42-year-old male presented with a giant thrombosed aneurysm of the left vertebral artery. The aneurysm was resected through a combined subtemporal and suboccipital approach after a saphenous vein bypass graft was placed between the right external carotid artery and the posterior cerebral artery. Intraoperative measurements of the blood flow volume and pressure demonstrated good blood flow in the bypass. Postoperatively, uncontrollable hypertension resulted in huge intracerebral hematoma formation and increased intracranial pressure. Control of systemic hypertension is essential in such patients.

Adult↗
PubMed1994

Facial nerve enhancement in Gd-MRI in patients with Bell's palsy.

The diagnostic value of a contrast enhanced MRI in patients with Bell's palsy was investigated. It was a characteristic finding that the internal acoustic meatal segment of the facial nerve was enhanced only on the affected side. The signal intensity ratio of the geniculate ganglion and the tympanic segment was significantly higher on the affected side than on the normal side. The severity of the facial palsy and the results of physiological examinations showed no relation to the results of MRI scans. Gd enhanced MRI thus appears to provide some useful findings for estimating the affected region of Bell's palsy, whereas it is not considered to be valuable in the diagnosis of severity.

Contrast Media↗
PubMed1994

Gd-DTPA enhanced MRI in Ramsay Hunt syndrome.

Ten patients with Ramsay Hunt syndrome underwent magnetic resonance (MR) scans. In many examinations, abnormal enhancement of the 7th nerve in the internal acoustic meatal segment through the mastoid segment was observed. Out of seven patients with cochlear and/or vestibular symptoms, only one showed abnormal enhancement of the 8th nerve, in addition to the 7th. The other 6 patients showed the same findings as in Bell's palsy, showing no enhancement of the 8th nerve. This suggests that clinical symptoms have no relation to the results of MRI. Enhanced MRI is the most sensitive means of making differential diagnoses between Hunt's syndrome and tumors, but it is impossible to detect all lesion sites corresponding to the symptoms in Hunt's syndrome.

Adult↗
PubMed1994

Effect of crystallization on fracture strength of castable glass-ceramics containing two crystals.

The relationship between fracture strength and crystallization in castable glass-ceramics was studied using castable glass-ceramics which contained crystalline apatite and magnesium titanate. Bending strength was increased with increases in crystal phases; 90, 124, 122 and 162 MPa were recorded for as-cast specimens and specimens cerammed at temperatures of 905 degrees, 925 degrees and 945 degrees C, respectively. The results of bending tests suggest that the crystallization of magnesium titanate is more effective than that of apatite in increasing the strength of glass-ceramics. Fracture toughness in specimens reheated at 905 degrees C was doubled compared with as-cast specimens. The apatite particles precipitated during ceramming treatment were thought to be an important factor in increasing both the fracture toughness and crack pinning effect.

Apatites↗
PubMed1994

[Intrabronchial neurilemmoma: a case report].

A 62-year-old woman who was pointed out abnormal shadow at left middle lung field in chest X-ray was followed up as a hamartoma from 1989. In this period, the tumor was growing up in chest X-ray and occupying the left segmental bronchus (B3) in bronchofiberscopic study. It was suspected neurilemmoma by the final biopsy examination. Left upper lobectomy was performed and pathohistological diagnosis was typical neurilemmoma that consist of Antoni type A and Antoni type B. Intrapulmonary or intrabronchial neurilemmoma is rare and only 20 cases have been reported in the Japanese literature.

Bronchial Neoplasms↗
PubMed1994

[Surgical treatment of intractable vasculitis syndromes--with special reference to Buerger disease, Takayasu arteritis, and so-called inflammatory abdominal aortic aneurysm].

Since the incidence of inflammatory arterial disease has been higher in Japan, its surgical treatment has been one of the main themes of vascular surgery from its beginning in this country. Buerger disease has been the main cause of chronic occlusive arterial disease before the middle of 1970s. and many patients suffered from intractable ischemic leg ulcer with severe pain. Reconstructive surgery, however, has been so much limited that number of the candidates for bypass surgery were around 10% of the patients, because of distal nature of the disease. We have developed a new technique in distal bypass surgery named as Esmarch's rubber bandage method, which was intended to minimize surgical injury to the host artery, and the results of its application to Buerger disease is very encouraging, and we have confirmed that this technique enables a bypass to the collateral arteries and muscular branches in place of the diseased tibio-peroneal artery. We expect this technique will clear a new avenue to surgical treatment of Buerger disease with limb threatening ischemia. In Takayasu's arteritis, the carotid reconstruction was popular between the late 1950s and 1960s and, at the same time atypical coarctation, renovascular hypertension, and aneurysm, along with their combined lesion became the objects of vascular surgery. This expansion of surgical indication contributed to the improvement of the prognosis and rehabilitation of the patients. Long term function of the reconstruction has been also confirmed. On the other hand, several problems emerged with the widespread application of vascular reconstruction which were peculiar to the disease state. Among them, the most important problems were neurological complications due to sudden increase in the intracranial blood pressure after carotid reconstruction, and anastomotic aneurysm as the delayed complication affecting eventual outcome which are inherent to the inflammation and extensive destruction of the medial component in this disease. A new method to prevent the postoperative neurological complications is discussed in this report. To improve the long term survival, meticulous observation of postoperative course is essential in Takayasu's arteritis. Recently, abdominal aortic aneurysms showing the peculiar gross appearance and clinical presentation have become the subject of discussion as inflammatory abdominal aortic aneurysm because of remarkable thickening of the aneurysmal wall and a severe inflammatory change, and some difficulties of its surgical treatment have been stressed in the most of the reports. The recent researches offered the conclusion that etiology of the aneurysm is not inflammation, but inflammatory reaction during formation of atherosclerotic aneurysm.(ABSTRACT TRUNCATED AT 400 WORDS)

Aortic Aneurysm, Abdominal↗
PubMed1994

[Atheromatous embolization as a cause of postoperative renal dysfunction in infrarenal aortic reconstructive surgery].

Influences of atheromatous changes in the aortic wall at the site of proximal clamping were studied retrospectively on postoperative renal function in an infrarenal aortic reconstruction. Atheromatous lesion was evaluated on CT scan as low density layer in the aortic wall observed in cases with the thickened wall exceeding 3mm, and they were classified into atheromatous group (group II) consisted of 21 patients. In these patients, the postoperative serum creatinine showed significant elevation from preoperative value of 0.89 +/- 0.32 mg/dl to 1.67 +/- 0.90 mg/dl on 1st postoperative day (p < 0.01), 1.25 +/- 0.99 mg/dl on 7th day (p < 0.05) and 1.24 +/- 0.89 mg/dl on discharge (p < 0.05). Correlation between the severity of the postoperative renal dysfunction and the degree of the atheromatous changes evaluated by preoperative CT scan was also defined and 2 patients with severe changes died of acute renal failure. On the contrary, 39 patients without thickened wall (group I) showed no significant elevation of serum creatinine after operation. These results strongly suggest that atheromatous embolization to the kidney plays an important role to cause postoperative renal impairment following infrarenal aortic reconstructive surgery for the patients with atheromatous changes in the aorta near the site of proximal clamping.

Acute Kidney Injury↗
PubMed1993

Hepatotoxicity of piperonyl butoxide in male F344 rats.

Male F344 rats were given 0, 0.6, 1.2 or 2.4% of piperonyl butoxide in the diet. At 1, 2, 4 or 12 weeks after the beginning of the experiment, liver and kidney weight and serum clinical parameters were determined and livers and kidneys were examined with light microscopy. From 1 or 2-12 weeks, distinct increase of liver weight, changes in serum clinical parameters for liver damage, oval cell proliferation, bile duct hyperplasia, single cell necrosis, enlarged and vacuolated hepatocytes, enlarged nuclei and anisonucleosis were seen in treated rats. From 4-12 weeks, cell infiltration, focal necrosis, multinucleated hepatocytes and prominent nucleoli of hepatocytes were seen in treated rats. At 12 weeks microgranulomas were seen in treated rats. Especially in rats of the 2.4% group at 12 weeks, severe enlargement of hepatocytes, severe enlargement of nuclei and multinucleated hepatocyte were seen, suggesting preneoplastic alteration. Relative kidney weights and serum urea nitrogen levels were increased in treated rats from 1 or 2-12 weeks and at 12 weeks, atrophy of proximal tubules, dilation of tubules, cell infiltration, fibrosis and accumulation of yellow-brown pigment in the proximal tubular cells were seen.

Administration, Oral↗
PubMed1993

Tissue-specific light-regulated expression directed by the promoter of a C4 gene, maize pyruvate,orthophosphate dikinase, in a C3 plant, rice.

Pyruvate,orthophosphate dikinase (PPDK; EC 2.7.9.1) activity is abundant in leaves of C4 plants, while it is difficult to detect in leaves of C3 plants. Recent studies have indicated that C3 plants have a gene encoding PPDK, with a structure similar to that of PPDK in C4 plants. However, low expression makes PPDK detection difficult in C3 plants. This finding suggests that high PPDK expression in C4 plants is due to regulatory mechanisms which are not operative in C3 plants. We have introduced a chimeric gene consisting of the gene encoding beta-glucuronidase (GUS; EC 3.2.1.31) controlled by the PPDK promoter from a C4 plant, maize, into a C3 cereal, rice. The chimeric gene was exclusively expressed in photosynthetic organs, leaf blades and sheaths, and not in roots or stems. Histochemical analysis of GUS activity demonstrated high expression of the chimeric gene in photosynthetic organs, localized in mesophyll cells, and no or very low activity in other cells. GUS expression was also regulated by light in that it was low in etiolated leaves and was enhanced by illumination. These observations indicate that the mechanisms responsible for cell-specific and light-inducible regulation of PPDK observed in C4 plants are also present in C3 plants. We directly tested whether rice has DNA-binding protein(s) which interact with a previously identified cis-acting element of the C4-type gene. Gel retardation assays indicate the presence in rice of a protein which binds this element and is similar to a maize nuclear protein which binds PPDK in maize. Taken together, these results indicate that the regulatory system which controls PPDK expression in maize is not unique to C4 plants.

DNA, Recombinant↗
PubMed1993

A case of an aortocolic fistula occurring 27 years after aorto-femoral bypass surgery, treated successfully by surgical management.

The secondary aortoenteric fistula (AEF) is a rare but grave complication of aortic reconstructive surgery. We report herein a case of an aortocolic fistula which occurred 27 years after an aortofemoral bypass. A 69-year-old man was admitted to hospital following a sudden episode of melena. He had undergone aortofemoral bypass surgery with a prosthetic graft 27 years previously for occlusive disease of the right external iliac artery. Colonofiberscopy, CT scan, and angiography were performed, and an aortocolic fistula due to an aortic anastomotic pseudoaneurysm was diagnosed. The first-stage operation, being resection of the previously implanted graft, right hemicolectomy, and aortic stump closure were carried out with concomitant axillo-right femoral bypass. A femoro-femoral crossover bypass was performed in the second stage and the patients recovery followed uneventfully. This case constitutes the longest postoperative interval for an AEF recorded in the English literature.

Aged↗
PubMed1993

Electron microscopic localization and expression on cultured cells of a novel surface-associated molecule in the rat central nervous system.

Subcellular localization and in vitro expression of a newly raised monoclonal antibody 374 antigen, which outlines a subset of neurons in various regions of the rat CNS, were studied. Electron microscopy revealed that the immunoreactivity is associated with the outer surfaces of neuronal subsets, the surfaces of glial cell processes facing such neurons and less frequently, with the Golgi apparatus and inner cell surfaces. The monoclonal antibody also stained part of the cytoplasm of a population of dendrites. In order to test whether the antigen originates from neurons, we examined the expression of the antigen in cultured cortical cells. Double immunofluorescence staining with neuron-specific enolase and glial fibrillary acidic protein revealed that the antigen is expressed on a subset of neuronal cells and to a lesser extent on glial cells. The antigen is considered to be expressed on the outer surface because the cells were stained by the monoclonal antibody irrespective of whether they were alive or fixed. The monoclonal antibody 374 antigen may be a novel neuronal surface molecule which plays a role in neuron-neuron or glial-neuron interactions in the CNS.

Animals↗
PubMed1993

Muscle pH/PCO2 monitoring.

The surface pH of skeletal muscle has been confirmed to be a sensitive indicator of peripheral muscle blood flow, but the development of a better electrode has been required. As a consequence, a unique and minute sensor was developed to measure muscle pH/PCO2. The purpose of this article was to evaluate this new monitoring device experimentally and clinically in order to clarify its effects, usefulness and specificity. Our experimental and clinical results showed that placement and measurements using the muscle pH/PCO2 monitor were easily and quickly accomplished without any complications. This small sensor provided an accurate assessment of vital physiologic functions and gave an early warning of clinical deterioration. The new monitor should be useful in pediatric surgery clinical management.

Animals↗
PubMed1993

Water transport model during CAPD: determination of parameters.

To minimize the total amount of glucose required for removing the same volume of water as a bolus, a continuous infusion of glucose during CAPD was proposed and studied. Both a computer simulation of water transport through the peritoneal membrane and in vivo assessment with rats were carried out to evaluate the feasibility of the newly proposed mathematical model in which lymphatic drainage of dialysate from the peritoneal cavity to lymphatic system was considered in addition to conventional water transport. Mass transport area coefficients (KA) of 0.041 to 0.063 ml/min/100 g body wt and 0.045 to 0.066 ml/min/100 g body wt were measured for glucose and urea during CAPD with male Wistar rats. Hydraulic conductivity of peritoneal membrane (Lc) was 7.9 x 10(-5) to 1.5 x 10(-4) ml/min/mm Hg/100 g body wt, which was calculated by a linear relationship between volume and osmotic pressure. Simulated water transport model using determined parameters indicated that the ratio of lymphatic transport to convective transport would be changeable in CAPD with glucose infusion at varying infusion rates, while up to 16% of the glucose uptake could be reduced compared with that of the common CAPD at the same dwell time.

Animals↗
PubMed1993

Expression of a rice homeobox gene causes altered morphology of transgenic plants.

We have isolated a cDNA clone encoding a homeobox sequence from rice. DNA sequence analysis of this clone, which was designated as Oryza sativa homeobox 1 (OSH1), and a genomic clone encoding the OSH1 sequence have shown that the OSH1 gene consists of five exons and encodes a polypeptide of 361 amino acid residues. Restriction fragment length polymorphism analysis has shown that OSH1 is a single-copy gene located near the phytochrome gene on chromosome 3. Introduction of the cloned OSH1 gene into rice resulted in altered leaf morphology, which was similar to that of the maize morphological mutant Knotted-1 (Kn1), indicating that OSH1 is a rice gene homologous to the maize Kn1 gene. RNA gel blot analysis has shown that the gene is primarily expressed in the shoot apices of young rice seedlings. This finding is supported by results of transformation experiments in which the 5' flanking region of the gene directed expression of a reporter gene in the shoot apex, particularly in stipules, of transgenic Arabidopsis. To elucidate the biological function of the OSH1 gene product, the coding region was introduced into Arabidopsis under the control of the cauliflower mosaic virus 35S promoter. Almost all transformants showed abnormal morphology. The typical phenotype was the formation of clumps of abundant vegetative and reproductive shoot apices containing meristems and leaf primordia, which did not form elongated shoots. Some transformants with a less severe phenotype formed elongated shoots but had abnormally shaped leaves and flowers with stunted sepals, petals, and stamens. The abnormal phenotypes were inherited, and the level of expression of the introduced OSH1 correlates with the severity of the phenotype. These findings indicate that the abnormal morphologies of the transgenic plants are caused by the expression of the OSH1 gene product and, therefore, that OSH1 is related to the plant development process.

Amino Acid Sequence↗