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Biomedical subjects

Y Okada

Publications and source records attributed to Y Okada.

At least 181 records · Page 10Linked to original sources
PubMed2001

[Hemodynamic effects of STA-MCA anastomosis on patients with occlusion of the main cerebral artery].

PURPOSE: We studied cerebral circulation in patients with occlusion of the main cerebral artery and investigated the efficacy of STA-MCA anastomosis. PATIENTS AND METHODS: Thirty-six patients with occlusion of the main cerebral artery were studied. Twenty-three patients had occlusion of the internal carotid artery and 13 had occlusion of the middle cerebral artery. The mean age was 62 years. Cerebral blood flow (CBF) was measured in all patients and cerebrovascular reactivity (CVR) was examined in 11 patients by xenon enhanced CT. Intraoperatively, cortical arterial pressure and anastomotic flow were measured. RESULTS: There was no perioperative mortality or morbidity. There was no ipsilateral stroke recurrence during the follow-up period averaging 35.1 months. Patency of the anastomosis was verified in 91% of the patients by magnetic resonance angiography. Twenty-three (64%) patients showed decreased CBF before the operation and 57% of these patients showed improvement to the normal range after STA-MCA anastomosis. All of the eight patients with decreased CVR showed improvement after the operation. Anastomotic flow correlated significantly with the cortical arterial pressure. CONCLUSION: STA-MCA anastomosis could improve cerebral circulation of patients with low CBF or low CVR due to occlusion of the main cerebral arterial. It was concluded that STA-MCA anastomosis may contribute to the reduction of stroke recurrence, if perioperative complications are reduced.

Aged↗
PubMed2001

Immunohistochemical characterisation of a case of insular thyroid carcinoma.

A case of insular thyroid carcinoma arising in the right lobe of a 54-year-old male is reported. The tumour exhibited an invasive growth pattern with regional lymph node metastasis. Microscopically, the tumour was characterised by well-defined solid nests like insulae, including mature follicles containing colloid and immature follicles without colloid. Immunohistochemically, tumour cells in follicular areas predominantly exhibited immunopositivity to antithyroglobulin antibody. On the other hand, diffuse immunoreactions with anti-neuron-specific enolase (NSE), S-100 protein and Leu-7 were detected mainly in the tumour cells of solid areas. In addition, clear cytoplasmic immunoreactivity with anti-myelin basic protein (MBP) antibody was exhibited in a number of tumour cells. Ultrastructurally, many tumour cells possessed dense vacuoles, apparently containing colloid material, but intracytoplasmic neurosecretory granules were absent. The histopathological and ultrastructural characteristics of the tumour as well as its anti-thyroglobulin antibody immunoreactivity support the classical hypothesis that this neoplasm is a variant of poorly differentiated thyroid carcinoma. The positive immunohistochemical reactions for NSE, S-100, MBP and Leu-7 raise the possibility of aberrant differentiation, for example neural.

Biomarkers, Tumor↗
PubMed2001

[Experience of direct hemoperfusion using polymyxin B-immobilized fiber on patients with endotoxin shock from urosepsis].

We report the effects of direct hemoperfusion using polymyxin B-immobilized fiber (PMX treatment) on two patients with endotoxin shock from urosepsis. In both cases, urosepsis caused by pyelonephritis from a ureteral stone progressed to endotoxin shock and disseminating intravascular coagulation (DIC). Single J catheter was indwelt in the ureter for the purpose of drainage before PMX treatment. Drainage of the origin of infection, using effective antibiotics and PMX treatment improved shock state and DIC earlier than we expected.

Anti-Bacterial Agents↗
PubMed2001

Mitral exposure technique for redo cardiac surgery. A left mediastinal pleurotomy and minimal adhesiotomy method.

We report an improved mitral exposure technique for mitral valve re-operation. Left mediastinal pleurotomy through a median sternotomy achieves rotation of the heart and excellent exposure of the mitral valve allowing the apex to drop posteriorly. We employed this technique in redo mitral valve surgeries for over a 3-year period. This minimal adhesiotomy method is technically simple, safe and time-saving.

Humans↗
PubMed2001

[Reevaluation of bronchoplasty for central-type lung cancer].

The outcome, anastomotic complications, and recurrence rate after bronchoplasty carried out in 198 patients with bronchogenic carcinoma in our institutions were evaluated retrospectively. The outcome of bronchoplasty was reasonable (5-year survival rate of 58%), but that of patients with adenocarcinoma was poor (5-year survival rate of 13%) because of their advanced stage and less complete resection. The complications of anastomosis occurred in 8.2% after bronchoplasty. Postoperative pneumonia significantly increased the risk of complications. There was no difference in the incidence of complications between patients who received end-to-end and telescope-type anastomosis. Local recurrence at the anastomosis occurred in 4.9% who underwent bronchoplasty, but in 28% who underwent carinal resection. Lymph node metastasis was a risk factor for local recurrence. Twenty patients with early superficial squamous cell carcinoma in the central bronchus were treated with photodynamic therapy without local recurrence. This new modality may be of benefit to selected patients.

Adenocarcinoma↗
PubMed2001

Preputial calculi: a case report.

The patient was a 92-year-old male whose chief complaint was urinary retention. The X-ray film showed multiple overlapping calcification shadows in the penile region. Renal insufficiency was speculated to be due to post-renal obstruction. Under the diagnoses of closure of the preputial orifice by balanoposthitis followed by urinary retention and preputial calculi, an urgent dorsal incision of the prepuce was made. Then, stone removal and indwelling catheter placement were performed. Renal function recovered soon after the operation, and the patient could urinate freely without catheterization. This case reminds us of the significance of surgical treatment for phimosis in elderly patients.

Aged↗
PubMed2001

[Incidence of systolic pulmonary venous flow reversal in patients with mitral valve prolapse: influence of the prolapse site].

OBJECTIVES: Systolic pulmonary venous flow reversal identified by pulsed Doppler echocardiography is useful for the diagnosis of severe mitral regurgitation. The direction of the mitral regurgitant jet in severe mitral regurgitation significantly influences the systolic pulmonary venous flow reversal in an experimental model. This study investigated the influence of the site of mitral valve prolapse on the incidence of systolic pulmonary venous flow reversal in patients with severe mitral regurgitation using transthoracic color Doppler echocardiography. METHODS: This study included 59 consecutive patients with severe mitral regurgitation (regurgitant fraction > 50%) due to mitral valve prolapse. Exclusion criteria were left ventricular ejection fraction < 45%, non sinus rhythms, associated aortic valve disease, bileaflet prolapse, and inadequate Doppler recordings. Right upper pulmonary venous flow was recorded and regurgitant fraction of mitral regurgitation measured by transthoracic color Doppler echocardiography. The sites of mitral valve prolapse were confirmed at operation in all patients. RESULTS: The incidence of systolic pulmonary venous flow reversal was 78% (14/18) in the patients with anterior leaflet prolapse, 82% (9/11) in the patients with medial commissure prolapse, 75% (12/16) in the patients with posterior middle scallop prolapse, 20% (2/10) in the patients with posterior medial scallop prolapse, and 25% (1/4) in the patients with posterior lateral scallop prolapse. There were no significant differences in regurgitant fraction between the five groups. The incidence of systolic pulmonary venous flow reversal was significantly lower in the patients with posterior medial scallop prolapse compared to the other sites of mitral valve prolapse (p < 0.01). CONCLUSIONS: Assessment of the severity of mitral regurgitation by systolic pulmonary venous flow reversal using transthoracic color Doppler echocardiography may be underestimated in patients with prolapse of the posterior medial scallop.

Aged↗
PubMed2001

[Not Available].

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Journal Article↗
PubMed2000

Association between two types of vitamin d receptor gene polymorphism and bone status in premenopausal Japanese women.

Polymorphisms in the vitamin D receptor (VDR) gene using ultrasound (US) bone mass and bone metabolic markers were investigated as potential genetic markers for osteoporosis in 126 premenopausal Japanese women aged 27.2 +/- 10.1 (mean +/- SD) years. The relationship between their VDR gene polymorphisms and bone states was determined. VDR genotypes were based on the absence (B) or presence (b) of the Bsm I restriction site (B polymorphism), and ATG (the M allele) and ACG (the m allele) sequences at the translation initiation site (M polymorphism). Genotype frequencies were 73.8%, bb; 24.6%, Bb; 1.6%, BB; 15.1%, MM; 51.6%, Mm and 33.3%, mm. The stiffness index of calcaneal bone minerals measured by an US bone densitometer was significantly higher in the mm types (P <0.05 versus MM) than in the Mm types (P <0.01 versus MM) and MM types. There was no significant difference between in B polymorphisms. Furthermore, bone mass was correlated with serum bone type alkaline phosphatase (ALP) activity and urinary deoxypyridinoline concentration in M polymorphisms. Because the distribution of B polymorphisms in each M polymorphism genotype did not differ, M polymorphisms were affected independently from B polymorphisms to bone mass or bone metabolic markers. No significant difference was observed in nutritional intake and food consumption among genotypes. In the MM and Mm types, the bone mass was closely related to the frequency of milk intake during the periods of elementary and junior high school. In contrast, bone mass was not associated with nutritional intake or the frequency of past milk intake in B polymorphisms. Therefore, the M polymorphism of the VDR gene is a stronger genetic indicator of osteoporosis than the B polymorphism in premenopausal Japanese woman.

Adult↗
PubMed2000

Brevican is degraded by matrix metalloproteinases and aggrecanase-1 (ADAMTS4) at different sites.

Brevican is a member of the lectican family of chondroitin sulfate proteoglycans that is predominantly expressed in the central nervous system. The susceptibility of brevican to digestion by matrix metalloproteinases (MMP-1, -2, -3, -7, -8, -9, -10, and -13 and membrane type 1 and 3 MMPs) and aggrecanase-1 (ADAMTS4) was examined. MMP-1, -2, -3, -7, -8, -10, and -13 degraded brevican into a few fragments with similar molecular masses, whereas the degradation products of aggrecanase-1 had apparently different sizes. NH(2)-terminal sequence analyses of the digestion fragments revealed that cleavages of the brevican core protein by these metalloproteinases occurred commonly within the central non-homologous domain. MMP-1, -2, -3, -7, -8, -10, and -13 preferentially attacked the Ala(360)-Phe(361) bond, whereas aggrecanase-1 cleaved the Glu(395)-Ser(396) bond, which are similar to the cleavage sites observed with cartilage proteoglycan (aggrecan) for the MMPs and aggrecanase-1, respectively. These data demonstrate that MMP-1, -2, -3, -7, -8, -10, and -13 and aggrecanase-1 digest brevican in a similar pattern to aggrecan and suggest that they may be responsible for the physiological turnover and pathological degradation of brevican.

ADAM Proteins↗
PubMed2000

Anaerobic glycolysis is crucial for the maintenance of neural activity in guinea pig hippocampal slices.

To investigate the functional significance of anaerobic and aerobic glycolysis on neural activity and levels of high energy phosphates, we tested the effects of glucose, mannose, fructose lactate, and pyruvate on the maintenance of neural activity and on the levels of ATP and creatine-P (CrP) in hippocampal slices. For an index of neural activity, population spikes (PS) evoked in the granule cell layer were monitored. Immediately after deprivation of glucose, the PS amplitude was gradually reduced and extinguished within 30 mm. Replacement of glucose with either lactate or pyruvate resulted in a decay and loss of PS with a similar time-course as observed during glucose deprivation. However, after the complete loss of neural activity for 10-20 min the PS reappeared and recovered to normal levels. The replacement of glucose with either mannose or fructose resulted in a transient decrease of the PS to 80-70% of the original amplitude in 20 mm, followed by recovery. The time-course of the decrease of PS in the mannose-containing medium was slower than that in the medium containing fructose and the time-course of recovery was faster. ATP and CrP were reduced to 90 and 70% of original level in each slice after glucose deprivation for 30 and 100 mm, respectively. In media containing either lactate, pyruvate, mannose, or fructose, the level of ATP and CrP was maintained at the original level. The anaerobic metabolic rate of glucose, mannose and fructose, determined by the rate of lactate production during complete anoxia, was consistent with the order of the decay and recovery of the PS in mannose and fructose-containing medium. The mode of the transient decay or loss of PS with no apparent reduction in the levels of ATP and CrP in each slice, in the presence of either mannose, fructose or lactate, indicates that anaerobic glycolysis is crucial for the maintenance of PS. The results obtained in this experiment are not in accordance with the reports by Schurr and Fowler in which they showed that lactate can support neural activity, although they did not measure the levels of ATP and CrP in slices. The present experiment disclosed that this discrepancy was due to the difference of slice preparation; namely rapidly prepared slice with shorter period anoxia (1 mm after removal of hippocampal tissue block) gives the results mentioned in the present study whereas slowly prepared slices by vibratome or chopper method with longer period of ischemia (5-20 mm), did not show transient loss of PS after application of lactate. Thus present experiment indicates that glycolytic process is essential for maintaining neural activity for physiological state of slices, if it is admitted to say that rapidly prepared slices is more physiological because they are exposed on shorter period of ischemia, and that more careful attention should be paid for the interpretation of the results of slice experiment according to the method of slice preparation.

Action Potentials↗
PubMed2000

Serotonin inhibits voltage-gated sodium current by cyclic adenosine monophosphate-dependent mechanism in bullfrog taste receptor cells.

We have investigated the effect of 5-hydroxytryptamine (serotonin) (5-HT) on the membrane properties of bullfrog taste receptor cells (TRCs) using patch-clamp technique. External application of 5-HT reversibly suppressed the voltage-gated Na(+) current (I(Na)) in about half of the TRCs sampled. The magnitude of suppression of peak I(Na) was dependent on the holding potential of the cell. Forskolin and cyclic adenosine monophosphate (cAMP) mimicked the suppressive effect of 5-HT on I(Na), but an internal protein kinase A-inhibitor potentiated I(Na). These results suggest that 5-HT suppresses I(Na) of bullfrog TRCs via protein kinase A-dependent phosphorylation, resulting in suppression of the excitability of bullfrog TRCs.

Animals↗
PubMed2000

Tri-n-butyltin-induced change in cellular level of glutathione in rat thymocytes: a flow cytometric study.

Since some of organotins, accumulated in edible mollusks of aquatic environments, exert a variety of toxic actions on experimental animals, it causes concern for the health of humans. We examined the effects of tri-n-butyltin chloride (TBT) and other organotins (triethyltin chloride, trimethyltin chloride, triphenyltin chloride and tetrabutyltin) on cellular content of glutathione (GSH) in rat thymocytes using a flow cytometer to further characterize the toxicity of TBT. When the cells were incubated with TBT at concentrations of 3 nM or more for 15 min, the cellular content of GSH dose-dependently decreased. However, it completely or partly recovered until 180 min even in the continued presence of TBT. This recovery was temperature-sensitive, suggesting an involvement of metabolic process. The efficacy of TBT to decrease the cellular content of GSH was greater than those of other organotins. Results suggest that TBT and some organotins at environmentally relevant (nanomolar) concentrations significantly reduce the cellular content of GSH, suggesting that they increase the vulnerability to some biological and chemical insults.

Animals↗
PubMed2000

Phosphofructokinase, a glycolytic regulatory enzyme has a crucial role for maintenance of synaptic activity in guinea pig hippocampal slices.

To clarify the importance of glucose metabolism in maintaining neural activity, we investigated the effects of lowering the concentration of glucose in perfusion medium on synaptic activity (population spikes, PS) and on the level of high energy phosphates in the region of dentate gyrus (DG), CA3 and CA1 area of hippocampal slices of guinea pig. Further we determined the activity of phosphofructokinase (PFK) and hexokinase (HK) of these areas. Lowering the concentration of glucose from 10 to 5, 4, 3, 1 and 0 (mM) caused a reduction in the PS amplitude. The PS in CA3 and CA1 region decayed and extinguished much faster than that in DG area. The ATP and CrP levels in these three areas were well preserved even after lowering the concentration of glucose to 3mM, and the patterns of reduction showed no difference in these three areas. On the other hand, there were significant differences in the activity of PFK in the DG, CA3 and CA1 areas, in contrast with HK which showed no significant differences. PFK activity was highest in the DG area and followed by CA3 and CA1 regions. The sensitivity in maintaining synaptic activity to lowered glucose concentrations showed good parallels with the activity of PFK in these regions, indicating that non-oxidative glycolytic metabolism regulated by PFK is crucial for the maintenance of synaptic activity

Action Potentials↗
PubMed2000

Ca2+-sensing receptor-mediated regulation of volume-sensitive Cl- channels in human epithelial cells.

Since extracellular Ca2+ or Mg2+ has been reported to modulate swelling-activated Cl- currents, we examined the expression of the G protein-coupled Ca2+-sensing receptor (CaR) and its involvement in the regulation of volume-sensitive Cl- channels in a human epithelial cell line (Intestine 407). Reverse transcriptase-polymerase chain reaction and immunoblotting analysis showed that Intestine 407 cells express CaR mRNA and protein. The swelling-activated whole-cell Cl- current was voltage-independently augmented by extracellular Ca2+ or Mg2+. In addition, Ca2+ or Mg2+ voltage-dependently accelerated the inactivation kinetics of the Cl- current. Neomycin, spermine and La3+ augmented volume-sensitive Cl- currents. However, these CaR agonists failed to affect depolarization-induced inactivation. Intracellular application of GTPgammaS, but not GDPbeta]S, increased the amplitude of the swelling-induced Cl- current without affecting the basal current. The upregulating effect of Ca2+ on the Cl- current amplitude was abolished by either GTPgammaS or GDPbetaS. In contrast, GTPgammaS and GDPbetaS failed to affect the inactivation kinetics of the Cl- current and the accelerating effect of Ca2+ thereon. The Cl- current amplitude was enlarged by stimulation with forskolin, dibutyryl cAMP and IBMX. During the cAMP stimulation, extracellular Ca2+ failed to increase the Cl- current but did accelerate depolarization-induced inactivation. It is concluded that stimulation of the CaR induces upregulation of volume-sensitive Cl- channels via a G protein-mediated increase in intracellular cAMP in the human epithelial cell. However, the accelerating effect of extracellular divalent cations on the inactivation kinetics of the Cl- current is induced by a mechanism independent of the CaR and cAMP.

Base Sequence↗