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Y Kai

Publications and source records attributed to Y Kai.

At least 109 records · Page 6Linked to original sources
PubMed1996

Orderly disposition of heterogeneous small subunits in D-ribulose-1,5-bisphosphate carboxylase/oxygenase from spinach.

We determined the crystal structure of spinach ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) by x-ray diffraction at 1.8-A resolution and found that the enzyme contained two kinds of S, SI and SII, present in equal number and disposed in an orderly way within the Rubisco holoenzyme. The electron density maps suggested that leucine was at residue 56 in SI, although histidine was at that position in SII. There were other residue differences. Thus, spinach Rubisco has a L8SI4SII4 subunit structure. The orderly disposition of the heterogeneous small subunits in the Rubisco holoenzyme provides accounts of a multigene family of S in plants.

Crystallography, X-Ray↗
PubMed1996

Intramedullary epidermoid cyst in the brain stem: case report.

BACKGROUND: The incidence of intracranial epidermoid cysts is between 0.2% to 1.8% of all brain tumors. They usually occur in the cerebellopontine angle or parasellar region. Intramedullary epidermoid cyst is rare and only nine cases have been previously reported. METHODS: A 69-year-old woman had progressive left hemiparesis for 2 years. Computed tomography scanning and magnetic resonance imaging (MRI) revealed that there was a cystic tumor in the pons that was compressing the brain stem. A part of the tumor cyst wall and the content of the cyst were surgically removed by right subtemporal transtentorial approach. The histologic diagnosis was epidermoid cyst. After the surgery, the left hemiparesis was improved and there was no sign of the tumor growth by MRI. CONCLUSION: The outcome of the previous cases with radical tumor resection was poor compared with the present case in which only a part of the cyst wall and the content were removed. Therefore, radical removal of the whole tumor may not be necessary for intramedullary epidermoid cyst of the brain stem.

Aged↗
PubMed1996

Crystallization and preliminary crystallographic studies of ribulose 1,5-bisphosphate carboxylase/oxygenase from a red alga, Galdieria partita, with a high specificity factor.

Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) from a red alga, Galdieria partita, has been crystallized by the hanging drop vapor diffusion method. Two forms (Forms I and II) of crystals were obtained under distinct conditions. The Form I crystal belongs to monoclinic space group C2 with cell dimensions of a = 190.2, b = 140.0, c = 189.0 A, and beta = 102.6 degrees, and diffracts up to 3.0 A resolution. Diffraction from the Form II crystal was too weak to determine crystal data.

Crystallization↗
PubMed1996

Increased secretion of triglyceride and cholesterol following inhibition of long-chain fatty acid oxidation in rat liver.

The effects of emeriamine, a fungal metabolite and a potent inhibitor of mitochondrial fatty acid oxidation, on ketogenesis and lipid secretion were examined in isolated perfused livers from 2-day-fasted rats. Liver perfusion with increasing concentrations of emeriamine up to 3 mumol caused a dose-dependent inhibition of ketone body production. The hepatic uptake of exogenous oleic acid substrate was comparable in the control and emeriamine-treated livers. The addition of 2 mumol emeriamine to the perfusion medium at either the beginning of perfusion or 2 h later caused immediate and almost complete cessation of ketone body production, which was accompanied by a concomitant decrease in the beta-hydroxybutyrate: acetoacetate ratio, suggesting a decreased production of NADH via mitochondrial beta-oxidation. Conversely, both triglyceride and cholesterol secretions were elevated, indicating a reciprocal response in ketogenesis and lipid secretion by the livers. The proportion of oleate in the perfusate triglyceride obtained from emeriamine-treated livers was significantly higher than that from control livers. In the post-perfused liver triglyceride, oleate was progressively increased in the livers treated with the inhibitor 2 h after perfusion and at the beginning of perfusion, respectively. These results indicate that direct inhibition of fatty acid oxidation diverts the exogenous fatty acids to the esterification pathway, and subsequently stimulate the synthesis and secretion of triglyceride and cholesterol. The fatty acid oxidation rate in the liver is, therefore, a critical determinant for the synthesis and secretion of these lipid components.

3-Hydroxybutyric Acid↗
PubMed1996

Two types of K+ currents underlying inward rectification of rat osteoclast membrane: a single-channel analysis.

1) Electrical membrane properties of spread type-osteoclasts were examined using the whole-cell and cell-attached configurations of the patch clamp technique. The membrane potential of the osteoclasts was measured and grouped into two populations: hyperpolarized and depolarized (around -80 and 0 mV, respectively). The current-voltage relation was N-shaped, showing the property of inward rectification which was produced by K+ conductance. Either Na+ or Ca2+ inward currents were not observed. 2) The single-channel recordings were made with osteoclasts of the hyperpolarized population. Two types (slow and fast) of the current were analyzed, which appeared predominantly and had large unit conductances. The reversal potential for both types shifted according to the equilibrium potential for K+. 3) The slow type had high open probabilities (> or = 0.85) at all potentials examined. The mean open time was 349 ms at the resting potential (RP) and had a tendency to become shorter with hyperpolarization of the membrane. The closed time histogram was fitted with a double exponential function, yielding closed times of 8.3 and 55.2 ms at RP, which were not changed by hyperpolarization. The unit conductance was 32.0 pS. No outward currents were recorded at depolarized potentials to RP. 4) The open probability of the fast type was 0.25 at RP and increased with hyperpolarization of the membrane (0.55 at -80 mV to RP). The mean open time was short (2.6 ms at RP), which became longer with hyperpolarization. The channel had two closed times, 2.8 and 15.3 ms at RP, which were not voltage dependent. The unit conductance was 38.8 pS in the range of hyperpolarization from RP. The amplitude of outward currents evoked by voltage pulses beyond RP was small, probably due to rapid flickering of the current. 5) The two types of single-channel K+ currents showed the inwardly rectifying property and may play an important role in the inward rectification seen in the whole-cell configuration.

Animals↗
PubMed1996

[Immunohistochemical study of androgen receptor in adenocarcinoma of the human prostatic cancer].

BACKGROUND: The anti-androgen therapy usually used to manage prostatic cancer is effective because the growth of adenocarcinoma of the prostate is influenced by androgens. However, some prostatic cancers do not respond to hormone therapy. Many studies have been conducted with the objective being to assess the responsiveness of prostatic cancer tissues by measuring the amount of androgen receptors (AR). The present study investigates the expression of AR in adenocarcinoma and in benign adenoma of the human prostate. METHODS: Formaline fixed paraffin sections of adenocarcinoma were prepared using 86 patients with primary prostatic cancer, seven patients with relapsed prostatic cancer, and 26 patients with BPH (as the control). Specimens were obtained by needle biopsy and immunohistochemical staining was performed. RESULTS: The benign adenoma AR were stained in the nuclei of the glandular epithelial cells. The receptor-positive and receptor-negative cells were intermingled with the malignant prostatic cells. The labelling indexes (LI) of the androgen receptor stain values in adenocarcinoma of the prostate (57.8 +/- 14.5%) in 86 patients were significantly lower than benign adenoma (86.4 +/- 6.3%) (p = 0.0001). And the LI were decreased with the progress of grades in malignancy: 72.8 +/- 7.5% in well differentiated; 58.7 +/- 7.3% in moderately differentiated; and 41.4 +/- 8.2% in poorly differentiated adenocarcinoma (p = 0.0001). Moreover, LI in relapsed case, all of which were poorly differentiated (22.9 +/- 13.6%), were significantly lower than the LI values of the primary cancer cases with poorly differentiated adenocarcinoma (p = 0.0004). Responders to anti-androgen therapy had high AR positive rate (p = 0.0001) and weakly stained cases had a lower survival rate than strongly stained cases (p = 0.03). CONCLUSION: These results suggest that the detection of AR with immunohistochemical study is useful for estimating the prognosis of the patients undergone anti-androgen therapy. And prostatic cancer cells are heterogeneously composed of clones of both androgen dependent and independent cancer cells before hormonal therapy is begun. And one reason why these tumors easily relapse with the progress of grades in hormonal therapy.

Adenocarcinoma↗
PubMed1996

[Targeted chemotherapy of hepatocellular carcinoma using Lipiodol as a carrier].

For targeted chemotherapy using Lipiodol as a carrier, it was found that anticancer agents had to be dissolved in Lipiodol and diffused gradually from it. Dose forms having properties for targeted chemotherapy were named "oily anticancer agents". Oily anticancer agents are completely different from simple mixture of Lipiodol and anticancer agents by pumping methods in antitumor activities and adverse effects. Up to 1,601 arterial injections of oily anticancer agents were given to 400 patients with unresectable hepatocellular carcinoma. Decrease in serum AFP levels was observed in 209 (94%) of 222 AFP-positive patients, and reduction of tumor size was observed in 308 (96%) of 322 patients who had evaluable tumors. Reduction in size to less than 50% was observed in 50% of patients 5 to 6 months after initial administration, and all tumors reduced to less than 50% one year after. In 45 of 60 patients whose tumors shrank to less than 10% of initial size, follow-up 1 year or more after tumor shrinkage could be done (range 1-9 years, average 3 years). These tumors did not regrow, so they were considered to be cured. Survival was prolonged, especially in 251 patients who were good candidates for therapy (excluding those with Child C liver cirrhosis, tumor occupying all four segments of the liver, and/or extrahepatic spread at initial arterial injection of the drug), the 1-, 2-, and 5-year survival rates were 83, 58, and 34%, respectively.

Adolescent↗
PubMed1995

Spectroscopic and electrochemical studies on active-site transitions of the type 1 copper protein pseudoazurin from Achromobacter cycloclastes.

The single type 1 copper protein pseudoazurin from Achromobacter cycloclastes gives reversible electrochemical behavior at a (4-pyridyl)disulfide-modified gold electrode. Measurements carried out at 25.0 degrees C indicate a midpoint reduction potential of E 1/2 = 260 mV versus normal hydrogen electrode at pH 7.0 and a peak-to-peak separation of delta Ep = 59 mV. The diffusion coefficient and heterogeneous electron transfer rate constant are estimated to be 2.23 x 10(-6) cm2 s-1 and 3.7 x 10(-2) cm s-1, respectively. Also, controlled potential electrolysis indicates a 1-electron transfer process and a formal reduction potential of 259 mV versus normal hydrogen electrode for the Cu(II)/Cu(I) couple. The heterogeneous electron transfer rate constant determined at the (4-pyridyl)disulfide-modified gold electrode at pH 4.6 is 6.7 x 10(-3) cm s-1, consistent with a slower process at the positively charged electrode surface. At pH 11.3, UV-visible, EPR, and resonance Raman spectra indicate a conversion of the distorted tetrahedral copper geometry to a trigonal structure. The trigonal form has elongated axial bonding and an axial EPR spectrum. At pH 11.3, the reduction potential is further decreased, and Cu-S bands in resonance Raman spectra at 330-460 cm-1 are shifted to higher energy (approximately 10 cm-1), consistent with a stronger Cu-S bond.

Alcaligenes↗
PubMed1995

Local anesthetics reduce the inhibitory neurotransmitter-induced current in dissociated hippocampal neurons of the rat.

The effects of local anesthetics on amino acid-induced currents were examined using the whole-cell configuration of the patch clamp technique in dissociated hippocampal pyramidal neurons of the rat. Lidocaine (3 mM) decreased the glycine-induced Cl- current (Gly-ICl) more potently (to 46% of the control value) than the gamma-aminobutyric acid-induced Cl- current (GABA-ICl; to 75%), whereas the agent had little effect on the excitatory glutamate response. The reduction in the Gly-ICl was dose-dependent, with a dissociation constant (KD) of 3 mM and a Hill coefficient of 0.96. A non-competitive inhibition was suggested by a double reciprocal plot of the effects of lidocaine on the concentration-response curve of the Gly-ICl. Benzocaine, a neutral local anesthetic at physiological pH, decreased the Gly-ICl more potently than lidocaine, while QX314, a permanently charged quaternary derivative of lidocaine, produced a much smaller inhibition, thereby indicating that the neutral form of local anesthetics is more effective in reducing the Gly-ICl. The depression of the Gly-ICl and GABA-ICl in central neurons may contribute to local anesthetic-induced convulsions.

Anesthetics, Local↗
PubMed1995

Relationship between evoked potentials and clinical status in spinal cord ischemia.

STUDY DESIGN AND METHODS: Sciatic neurogenic motor-evoked potentials, spinal evoked potentials, and somatosensory-evoked potentials were recorded in 12 anesthetized dogs that had arterial ischemia of the lumbar cord produced by ligation of segmental arteries. The presence or absence of the above-mentioned potentials was compared with the clinical status of repeated wake-up tests. RESULTS: Although these results were complicated, sciatic neurogenic motor-evoked potential was more sensitive to the spinal cord ischemia and was a better predictor of clinical outcome than spinal evoked potential and somatosensory-evoked potential. However, the presence was not a guarantee of normal function. The initial morphologic change of these potentials secondary to ischemia consisted of a decrease in amplitude and in the number of peaks without a shift of latency. CONCLUSIONS: The present study suggests that the peripheral neurogenic motor-evoked potential is a better warning system for spinal cord ischemia and that its adoption may contribute to the prevention of cord ischemia during spinal surgery, whereas somatosensory-evoked potential and spinal evoked potential cannot be indices.

Animals↗
PubMed1995

Using Ga-67 scintigraphy in prostatic abscess.

The use of Ga-67 scintigraphy (Ga) in prostate inflammatory diseases may be restricted by the difficulty in distinguishing between the accumulation of Ga-67-citrate (Ga-citrate) in the lesion and feces. The diagnosis of prostatic abscess has been mainly made by other radiologic methods without scintigraphic studies and no finding of Ga has been reported. This patient demonstrated that coordinating the findings of Ga-citrate accumulation can be helpful in making a prompt diagnosis of a possibly fatal prostatic abscess, especially in those patients with poorly defined clinical symptoms and high risk factors.

Abscess↗
PubMed1995

Thrombosed growing giant aneurysms of the vertebral artery: growth mechanism and management.

Results in three patients with thrombosed giant aneurysms of the vertebral artery are reported. Each of the aneurysms presented as a mass lesion. On postcontrast computerized tomography and magnetic resonance imaging, each aneurysm demonstrated a patent lumen and intrathrombotic vascular channels. Two patients died and were autopsied, and the other patient was successfully treated. Pathological examination revealed that the aneurysms had staged clots, an open lumen, intrathrombotic channels with endothelial lining, and aneurysmal walls with intimal thickening. The authors suggest that the development of the intrathrombotic capillary channels may be an important factor in the growth of thrombosed giant aneurysm of the vertebral artery. Trapping of the aneurysm followed by aneurysmectomy appears to be the best treatment for this type of aneurysm.

Adult↗
PubMed1995

[Transient tracheal obstruction during surgical correction of scoliosis in a patient with Marfan's syndrome].

A 13-yr-old male with Marfan's syndrome underwent surgical correction of severe scoliosis. He had not manifested dyspnea previously in any position. Under anesthesia with thiamylal and vecuronium, his trachea was intubated with a reinforced endotracheal tube without any difficulty. Anesthesia was maintained with nitrous oxide and fentanyl, 8 micrograms.kg-1. The patient was placed in a prone position. Thirty min after the start of operation, when orthopedists compressed the thoracic vertebrae vertically, positive pressure ventilation became impossible abruptly, even with a high airway pressure. Three min later, ventilation became possible after cessation of compression and by mouth-to-tube insufflation. SpO2 monitored with a pulse oximeter recovered immediately from 61% to 99%. A capnogram showed a lengthy retardation of an inspiratory phase. Emergency fibreoptic bronchoscopy revealed that the trachea had been compressed vertically; the compression was reduced by moving the chest supporters laterally. After the apneic episode, the operation continued uneventfully, and he was discharged a month later. A severe deformity of the thorax due to severe scoliosis and weak tracheal tissue due to connective tissue defect caused partial tracheal compression before the surgery, and made his trachea susceptible to complete obstruction by vertical external compression on the thorax. Patients with Marfan's syndrome and scoliosis should have careful preoperative airway evaluation. The selection and positioning of endotracheal tubes should be done with care. During surgery, the patient's body position and the condition of the trachea should be checked frequently. Capnography and fiberoptic bronchoscopy seem to be mandatory for early detection of tracheal stenosis and prevention of tracheal obstruction.

Adolescent↗
PubMed1995

[Expression of PCNA/cyclin, p53, C-erbB-2 versus histological grade in transitional cell carcinoma of urinary bladder].

It is important to know the proliferating ability and the malignant potential of tumor tissues. We have examined the expression of PCNA/cyclin, p53 and C-erbB-2 in transitional cell carcinoma of the human urinary bladder by an immunohistochemical method, and compared the results with the histological grade, stage and survival rate. Immunohistochemical studies, using monoclonal and polyclonal antibodies, on these proteins were performed with formaline fixed-paraffin sections of tumor tissue from 40 patients with bladder cancer. Generally, a higher grade and higher stage tumors expressed PCNA/cyclin, p53 and C-erbB-2 with a greater frequency than the tumors with a lower grade and lower stage and strongly stained cases had a lower survival rate than weakly stained cases. These findings suggest that the detection of each antigen is useful for estimating the malignant potential of transitional cell carcinoma as the adjuvant studies, because of its applicability to paraffin-embedded tissue sections and its simple, rapid technique.

Adult↗
PubMed1994

Relationship between evoked potentials and clinical status in spinal cord ischemia.

STUDY DESIGN: Sciatic neurogenic motor-evoked potentials (sciatic-NMEP), spinal-evoked potentials (spinal-EP), and somatosensory-evoked potentials (SEP) were recorded in the lumbar cord during progressive ligation of segmental arteries. Relationship between electrophysiologic assessment and clinical status was studied. OBJECTIVES: In 12 anesthetized dogs that had arterial ischemia of the lumbar cord produced by ligation of segmental arteries, the aforementioned evoked potentials were recorded, and their presence or absence was compared with the clinical status of repeated wake-up tests. SUMMARY OF BACKGROUND DATA: Both sciatic-NMEP loss and ligation level producing cord ischemia were not associated with severity of wake-up test. Sciatic-NMEPs were lost earlier than spinal-EP and SEPs after progressive ligation. The false-negative rate of sciatic-NMEP, SEP at high spine and at low spine was 12.5%, 20.8%, and 41.7%, respectively. The waveform morphology of potentials by cord ischemia decreased in amplitude and in the number of peaks without a shift of latency. METHODS: First, baseline NMEPs and SEPs were obtained, lumbar arteries were ligated, evoked potentials were recorded continuously, and wake-up test was administered. If sciatic-NMEPs were not lost, intercostal arteries were ligated, and potentials and clinical status were reassessed. RESULTS: Though these results were complicated, sciatic-NMEP was more sensitive to the spinal cord ischemia and a better predictor of clinical outcome than spinal-EP and SEP. However, the presence was not a guarantee of normal function. Somatosensory-evoked potentials are not a good predictor of clinical motor status. The initial morphologic change of these potentials secondary to ischemia consisted of a decrease in amplitude and in the number of peaks without a shift of latency. CONCLUSIONS: The peripheral-NMEP is a better warning system to spinal cord ischemia and its adoption may prevent cord ischemia during surgery, whereas SEP and spinal-EP can not be indicies.

Animals↗
PubMed1994

Refined crystal structure of pseudoazurin from Methylobacterium extorquens AM1 at 1.5 A resolution.

The crystal structure of pseudoazurin from Methylobacterium extorquens AM1 (PAZAM1) has been solved by the molecular replacement method using copper-copper distances as translation parameters, which were obtained from difference Patterson maps calculated with the synchrotron radiation data containing the multiwavelength anomalous-dispersion effect. The structure refinement was carried out by the use of molecular dynamics optimization and the restrained least-squares method. The final crystallographic R factor was 19.9% for the 14 365 reflections greater than 3sigma between 1.5 and 8.0 A resolution. This report describes the characteristic features of the structure of PAZAM 1 as well as the effectiveness of synchrotron radiation for structure analysis of metalloproteins. The environment of the metal active site and the structural differences among blue-copper proteins are discussed.

Journal Article↗