PubMed Health⌕ Search

Biomedical subjects

Y Ueda

Publications and source records attributed to Y Ueda.

At least 55 records · Page 3Linked to original sources
PubMed1992

Efflux of glutamate produced by short ischemia of varied severity in rat striatum.

BACKGROUND AND PURPOSE: Evidence has accumulated suggesting that ischemia-induced neuronal damage may be linked to an extracellular overflow of glutamate. The purpose of this study was to provide new information about the time course of the increase in extracellular glutamate concentration associated with moderate and severe ischemia, and its relationship with electrical changes including anoxic depolarization. METHODS: Changes in the extracellular concentration of glutamate were continuously monitored in the rat striatum by microdialysis. Ischemia was induced by four-vessel occlusion for 3 or 5 minutes, and in some cases its severity was increased with a neck tourniquet. The severity of ischemia was assessed by electroencephalogram and direct current potential recording to detect anoxic depolarization. RESULTS: In all experiments, the extracellular glutamate concentration began to increase shortly after the onset of ischemia and steadily rose throughout the ischemic period. Increases up to 35.0 mumol/l (2-3 mumol/l baseline; p less than 0.005) were observed when ischemia provoked the rapid occurrence of a large and sustained anoxic depolarization. Relatively smaller but still significant increases (6.9 mumol/l; p less than 0.005) were observed in penumbral conditions (electroencephalogram loss without anoxic depolarization). Glutamate began to be cleared immediately after reperfusion and 90% of released glutamate was cleared within 5 minutes, even when the preceding ischemia had been severe. CONCLUSIONS: We propose that the extracellular glutamate concentration may not reach critical levels during short episodes of penumbral ischemia, but this might happen with a longer ischemic period.

Animals↗
PubMed1992

Changes in extracellular glutamate concentration produced in the rat striatum by repeated ischemia.

BACKGROUND AND PURPOSE: Evidence suggesting that ischemia-induced neuronal damage may be linked to an extracellular overflow of glutamate has accumulated, and previous studies have shown that repetitive ischemic insults may have a cumulative effect. The purpose of this study was to investigate changes in the extracellular glutamate concentration produced by repeated brief ischemic episodes of varied severity. METHODS: Four consecutive 3- or 5-minute periods of bilateral hemispheric ischemia were produced in rats, each ischemic period followed by 27 minutes of reperfusion. Extracellular glutamate in the striatum was monitored using microdialysis, and the electroencephalogram and extracellular direct current potential were recorded in the same tissue site to assess the severity of ischemia. RESULTS: The results suggest that the kinetics of the increase in the extracellular glutamate concentration produced by a brief ischemic episode are similar, irrespective of whether it is a single insult or part of a repeated sequence. In all cases, the extracellular glutamate concentration increased throughout ischemia and returned to its preischemic level early during reperfusion. The pattern of changes in the ischemia-induced glutamate overflow during repetitive insults varied with the severity of ischemia, in common with the pattern of changes in the direct current potential, supporting the concept that ionic changes associated with anoxic depolarization are a major determinant of ischemia-induced glutamate overflow. CONCLUSIONS: There may be no cumulative effect of brief repeated episodes of ischemia on the extracellular glutamate concentration, even though repeated 5-minute ischemic episodes apparently caused progressive deterioration of ionic homeostasis in some cases.

Animals↗
PubMed1992

Clinical management of boric acid ingestion: pharmacokinetic assessment of efficacy of hemodialysis for treatment of acute boric acid poisoning.

Seven hours after suicidal ingestion of about 21 g of boric acid, a 26-year-old female admitted to our hospital in a state of slightly impaired consciousness, with frequent vomiting, shivering, fever and skin flush. Immediately, gastric lavage, followed by administration of activated charcoal and laxative (MgSO4), was performed. In order to ensure her urination, fluid infusion therapy was conducted with the aid of diuretics (furosemide). Since the serum concentrations of boric acid was very high, hemodialysis was carried out twice during the first 39 h. She responded well to the above mentioned treatment and was discharged 12 d post-admission without any sequelae. The concentrations of boric acid in serum and urine were measured in appropriate intervals with our modified Miyamoto's method, and the pharmacokinetics of boric acid were analyzed. The concentration of boric acid in serum and urine at the beginning of treatment was 465 micrograms/ml and 3.40 mg/ml, respectively. The half-life of boric acid in serum was 13.46 h, whereas it was shortened to 3.76 h during hemodialysis. The total body clearance was 0.99 l/h, while it increased to 3.53 l/h by hemodialysis. The additional removal of boric acid by hemodialysis was estimated to be about 5 g. It was concluded that the hemodialysis was very useful in the treatment of boric acid poisoning, because it accelerated the elimination of boric acid about four times faster than with conventional treatment.

Acute Disease↗
PubMed1992

Loss of nocturnal decline in blood pressure in diabetic patients with autonomic neuropathy.

We investigated loss of the nocturnal decline in blood pressure (BP) and its mechanism in diabetes mellitus with autonomic neuropathy (ANP). BP was measured every 30 min using ambulatory BP recorders in 52 diabetic patients and 11 nondiabetic controls. As an index of autonomic nervous dysfunction, CVRR (the coefficient of variation of the R-R interval on ECGs) and diastolic blood pressure response on standing were measured. Plasma volume (PV) was measured with RISA. The difference between daytime mean BP (09:00 to 13:00) and nighttime mean BP (01:00 to 05:00) was analyzed. The normal control group showed a significant reduction in mean BP during the nighttime (-12.8 +/- 7.5 mmHg) as compared with the DM group (-3.3 +/- 8.6 mmHg, p < 0.001). The diabetic patients with loss of the nocturnal decline in blood pressure showed autonomic nervous dysfunction and increased PV. In conclusion, the nocturnal elevation of blood pressure might result from an imbalance between reduced tone of sympathetic and parasympathetic functions in addition to the postural effect and increased plasma volume present in diabetic patients.

Adult↗
PubMed1992

[Biological effects of exposure to high frequency electromagnetics on rabbits and guinea pigs].

To investigate the biological effects of exposure to feeble high frequency electromagnetism, skin surface temperature, blood vessel (arterioles and venules) diameter were examined, using infrared thermography, a laser doppler flowmeter, and a video microscope, respectively, in the ear of rabbits. After exposing the ear of rabbits to high frequency electromagnetism value of 9 MHz for 15 minutes, continued rising of local temperature was demonstrated. Though dilatation of arterioles was not seen. In addition, venules tended to dilate and blood flow also to increase, and microcirculation was accelerated at the site where electromagnetism was exposed. Hazardous effects of long term exposures of high frequency electromagnetism (9 MHz for 30 days, 8 hours/day) on guinea pigs were not observed in their behavior, food consumption, body and organ weights, hematological and biochemical values, macroscopic and microscopic findings on autopsy.

Animals↗
PubMed1992

Multiple endocrine neoplasia type 2A.

A 40-year-old woman was admitted with complaints of headache, palpitation and diaphoresis. She had undergone right hemithyroidectomy 12 years previously. Histological reexamination of the operative specimen revealed a medullary thyroid carcinoma. Abdominal ultrasonography, CT scan and angiography showed bilateral adrenal tumors. Serum catecholamine levels in both adrenal veins were high. Based on these data, bilateral adrenalectomy was performed. Histological examination confirmed the diagnosis of pheochromocytomas. After operation, serum calcitonin and urinary noradrenaline levels were still high. Further examination by 131I-metaiodobenzylguanidine (MIBG) scintigraphy is planned.

Adrenal Gland Neoplasms↗
PubMed1992

Synthesis and in vitro activity of novel quaternary ammonium carbapenems: 2-pyridiniopropyl and 1-pyridinioethyl carbapenems.

The synthesis of new carbapenems having either a pyridiniopropyl group at the 2-position or a pyridinioethyl group at the 1-position is described, along with the preparation of their corresponding hydroxy and acetoxy analogs. The antibacterial activity, susceptibility to dehydropeptidase-I (DHP-I) enzyme and chemical stability of these new carbapenems are also reported. 2-Pyridiniopropyl-carbapenem 4 was found to possess excellent antibacterial activity. It was more stable chemically and less susceptible to the DHP-I enzyme than the thio analog 3. 1-Pyridinioethylcarbapenem 5 showed significantly reduced antibacterial activity as compared to 2-pyridiniopropylcarbapenem 4.

Carbapenems↗
PubMed1992

[Non-Hodgkin's lymphoma with primary osseous manifestation, from the files of the Bone Tumor Registry of Westphalia].

30 cases of non-Hodgkin-lymphoma with primary bone manifestation were selected from the files of the Bone Tumor Registry of Westfalia from 1975 until 1992. Clinical data and radiologic aspects were evaluated. 60% of the lesions were localized within the long bones (femur 10, humerus 6, tibia 2). The lymphomas were classified based on paraffin-embedded material in combination with immunohistochemical findings according to the updated Kiel-classification. 29 B-cell lymphomas and one T-cell lymphoma of medium-sized pleomorphic type were found. 5 B-cell lymphomas were of low and 23 of high malignancy. Almost 50% of the tumors were of centroblastic type. The Kiel-classification was not applicable for one lymphoma, 3 others could not be subclassified because of shrinking artefacts. Prognosis in patients with localized disease (9 cases) was favorable, whereas only 25% of patients with generalized disease (12/cases) survived for 3 years or longer.

Bone Neoplasms↗
PubMed1992

Application of L-DNA to the study of the specific DNA recognition mechanism of bleomycin.

The hexadeoxynucleotide analog, L-d(CGCGCG) composed of L-deoxyribose was synthesized and clearly shown to have the same conformation and dynamic properties with natural D-d(CGCGCG) except for chirality with CD spectra. This unnatural hexanucleotide was not cleaved by bleomycin, an antitumor DNA cleaving drug, but was able to bind to the DNA binding domain of bleomycin to a similar extent with the natural one. These results strongly suggest the importance of the other moiety than the DNA binding domain for the specific DNA recognition of bleomycin. Thus, L-oligonucleotides are useful for the study of DNA-drug interactions.

Binding Sites↗
PubMed1992

[Effect of weight loss on the reduction of blood pressure in obesity hypertension--hyperinsulinemia and renal sodium retention].

The role of insulin and dopamine on blood pressure and renal sodium excretion was evaluated in 10 obese hypertensive patients. Essential hypertensive subjects (age 49.7 +/- 7.7) with at least 26.0kg/m2 obesity were hospitalized and a 2000k cal diet for 7 days (control periods) followed by a 800 k cal for 21 days were given. Salt intake was maintained at 10 g/day throughout this study. Mean blood pressure (MBP), plasma insulin (IRI), urinary dopamine and fractional excretion of sodium (FENa) were measured in both diet periods. Body mass index significantly decreased from 31.6 +/- 4.6kg/m2 to 28.6 +/- 4.1 kg/m2 after weight reduction (P < 0.001). MBP significantly lowered from 112.8 +/- 14.1 mmHg to 100.4 +/- 12.4 mmHg (P < 0.01) and IRI from 9.11 +/- 5.0 microU/ml to 6.3 +/- 5.5 microU/ml (P < 0.001) after weight loss. We observed a significant correlationship between delta MBP and delta IRI (r = 0.754, P < 0.01). Also, we observed a significant correlationship between delta MBP and delta FENa (r = -0.835, P < 0.01). A significant relationship was observed between urinary excretion of sodium and urinary excretion of dopamine (r = 0.507, P < 0.05). We concluded that sodium retention and increase of sympathetic nervous activity by hyperinsulinemia might play an important role of hypertension, and blood pressure reduction by weight loss resulted from decreased insulin and increased excretion of sodium in obesity hypertension.

Adult↗
PubMed1992

[Immunohistochemical studies of paraneoplastic subacute sensory neuropathy--an analysis of antineuronal antibody and infiltrated lymphocytes].

In order to clarify the pathogenesis of paraneoplastic syndrome, immunohistochemical studies were performed in a patient with subacute sensory neuropathy secondary to a small cell lung cancer. The case was a 73-year-old ex-farmer, whose chief complaints were pins and needles sensation of distal limbs and gait difficulty. After 6 weeks prodromata of pain in the upper limbs and numbness in all the limbs, he became unable to stand up without assistance. Neurological examinations on admission revealed marked sensory disturbances with glove and stocking type hypalgesia to pin prick and the loss of position and vibration senses in the distal extremities. His deep tendon reflexes also decreased in all the limbs. A chest X-ray showed a mass in the left upper lung field. A transbronchial lung biopsy of the mass revealed a small cell carcinoma. He was treated with anti-cancer drugs and radiation but he died of pneumonia after 8 months illness. Autopsy revealed a marked demyelination of the entire posterior column of the spinal cord. Dorsal root ganglia were infiltrated by lymphocytes with significant neuronal loss. Immunohistochemically, most of the infiltrated cells around the neurons were classified as CD8+ with fewer CD4+ lymphocytes. No B-lymphocytes were detected in the ganglia. The HLA-ABC and HLA-DR positive cells were found only among the satellite cells, not in the neurons. The serum and CSF from the patient were immunohistologically reacted with the nuclei and cytoplasm of all neurons of human as well as of rats, indicating the presence of anti-Hu type antineuronal antibody in the patient's CSF as well as serum.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Effects of cell differentiation on the synthesis of the third and fourth component of complement (C3, C4) by the human monocytic cell line U937.

Association of complement synthesis with cell differentiation in U937 cells was investigated using granulocyte-macrophage colony-stimulating factor (GM-CSF), vitamin D3 and interferon-gamma (IFN-gamma) as differentiation-inducing agents. GM-CSF or vitamin D3 enhanced the synthesis of the third component of complement (C3) by U937 cells, but had no stimulatory effect on the synthesis of the fourth component of complement (C4). IFN-gamma increased both C3 and C4 synthesis by U937 cells. Combination of two of these three agents resulted in synergistic enhancement and all three agents caused maximal enhancement of C3 synthesis. Vitamin D3 enhanced IFN-gamma-induced C4 synthesis by U937 cells. These results were confirmed by ELISA and SDS-PAGE after biosynthetic labelling. GM-CSF, vitamin D3 or IFN-gamma increased the expression of complement receptor type 3 (CR3), one of the markers of monocyte/macrophage differentiation. Two of these agents caused a further increase and all three agents maximal increase in CR3 expression. Since C3 was synthesized in parallel with the degree of CR3 expression, the synthesis of C3, but not C4, by U937 cells is thought to be closely related to cell differentiation. It was reconfirmed that the synthesis of C3 and C4 by U937 cells was independently regulated.

Cell Differentiation↗
PubMed1992

Tumor-specific chemoimmunotherapy of murine fibrosarcoma using tumor-specific transplantation antigen, cyclophosphamide, and interleukin-2.

The anti-tumor effect of active specific chemoimmunotherapy, using butanol-extracted tumor-specific transplantation antigen (TSTA), cyclophosphamide (CY), and continuous intrasplenic infusion of interleukin-2 (IS-IL-2), was assessed in a C3H/HeJ murine methylcholanthrene (MCA)-induced fibrosarcoma model. Sole administration of TSTA induced tumor-specific, suppressor T cells in the spleens of mice bearing 3-day established tumors. Concomitant low-dose (20 mg/kg) CY treatment not only inhibited TSTA-mediated suppressor cell induction, but also evoked splenic lymphocytes of tumor-bearing mice to display tumor-specific cytotoxic activity. High-dose (200 mg/kg) CY abrogated the immunotherapeutic benefit. The immune effectors generated by TSTA plus CY bear the Thy 1, L3T4, Lyt 2 phenotype. Continuous IS-IL-2 infusion in combination with TSTA and CY induced tumor-specific Lyt 2+ cytolytic T cells, as well as the activation of L3T4+ cytostatic T cells. Thus, a triple regimen using TSTA, CY, and IS-IL-2 appears to augment CTL induction in tumor-bearing hosts undergoing stimulation of helper elements by TSTA and inhibition of suppressor cells by CY.

Animals↗
PubMed1992

[Mathematical simulation of intracranial condition--Part 1. Linear model stimulation].

We developed a linear mathematical model of the intracranial vessels, which reflects changes of the pulse wave (pulse pressure) of intracranial pressure after ligation of the internal jugular vein. The model composed of eight major variables: 1. resistance of arteries, 2. resistance of small arteries and capillary vessels, 3. resistance of veins, 4. resistance of internal jugular and vertebral veins, 5. compliance of arteries, 6. compliance of small arteries and capillary vessels, 7. compliance of veins and 8. intracranial compliance. All variables are presumed to have linear elements and replaced with electrical elements. The model of neck dissection is expressed as the change of resistance of the internal jugular and vertebral veins. Intracranial condition is expressed as the pulse wave (pulse pressure) of intracranial pressure and driving pressure. After unilateral ligation of the internal jugular vein, the pulse wave of intracranial pressure increased 24% and, after bilateral ligation of the internal jugular vein, it increased 55%. After unilateral ligation of the internal jugular vein, the pulse wave of intracranial pressure increased 27%, and, after bilateral ligation, it increased 79%. When intracranial compliance is normal, the respective ratios of pulse wave of intracranial pressure and driving pressure to cross-sectional area decreased, whereas those after increase of intracranial compliance increased.

Cerebrovascular Circulation↗