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Biomedical subjects

K Kamiya

Publications and source records attributed to K Kamiya.

At least 235 records · Page 13Linked to original sources
PubMed1990

ATP directly affects junctional conductance between paired ventricular myocytes isolated from guinea pig heart.

Effects of ATP on junctional conductance (gj) were investigated in paired ventricular myocytes isolated from guinea pig hearts. One cell of the pair was voltage-clamped with a single-patch pipette, and gj was measured after the perforation of the nonjunctional membrane of the partner cell. The current-voltage relation of gj was linear between -30 and +30 mV. The control gj at 5.0 mM ATP in 88 pairs of cells ranged from 100 to 1,055 nS (average, 268 nS). ATP within the range from 0.1 to 5.0 mM increased gj in a dose-dependent manner. The Hill coefficient was 2.6, and the half-maximum effective concentration of ATP was 0.68 mM. Adenylylimidodiphosphate (2 mM) caused a transient increase in gj in the presence of 0.5 mM ATP, but forskolin (30 microM), cyclic AMP (50 microM), catalytic subunit of cyclic AMP-dependent protein kinase (1 microM), and ADP (10 mM) had no significant effect on gj. The temperature coefficient of gj in the presence of 5.0 mM ATP was 1.29. These findings suggest that gj in paired ventricular myocytes is directly regulated by ATP probably through a specific ligand-receptor interaction between ATP and gap junctional channel protein.

Adenosine Diphosphate↗
PubMed1990

Huge calcified epidural abscess--case report.

A 76-year-old female with an intracranial epidural abscess having a long history of about 30 years is presented. Craniogram, carotid angiogram, and computed tomographic scan showed a huge calcified lesion with hyperostosis at the right parietal region. The abscess appeared to have granulated and calcified due to long-lasting stagnation of the pus.

Aged↗
PubMed1990

Saccular aneurysm of the distal anterior choroidal artery--case report.

The authors report a case of a distal anterior choroidal artery aneurysm in a 75-year-old female who presented with nausea, vomiting, and severe headache. Computed tomographic (CT) scans revealed a hematoma in the right lateral ventricle and a subarachnoid hemorrhage in the right parasellar-Sylvian cistern. Cerebral angiography showed a saccular aneurysm at the right distal anterior choroidal artery. The authors intended to operate at the chronic stage, and carried out conservative management. After 1 month her condition suddenly worsened and she died, although a CT scan showed no remarkable changes. At autopsy, a pulmonary artery thrombosis was considered the cause of death. The aneurysm was identified in the temporal horn of the right lateral ventricle, and was a true aneurysm.

Aged↗
PubMed1990

Effect of clot removal on cerebral vasospasm.

The effect of clot removal on cerebral vasospasm was studied in 104 patients with aneurysmal subarachnoid hemorrhage (SAH). The series included patients who fulfilled all of the following criteria: operation was performed by Day 3 after the ictus; the patient's preoperative clinical grade was between Grades I and IV; there was no rebleeding; computerized tomography (CT) showed only SAH; and carotid angiograms were performed by Day 2 and repeated between Days 7 and 9. Both the degree of SAH on CT and angiographic vasospasm were graded from 0 to III. The relationship of the SAH grade in the basal frontal interhemispheric fissure (IHF) to the presence of vasospasm at the A2 segments of the anterior cerebral artery and the relationship of the SAH grade in the sylvian stems to the presence of vasospasm at the M1 segments of the middle cerebral artery were analyzed. Correlation of preoperative and postoperative SAH grades with the angiographic vasospasm grades, with the incidence of symptomatic vasospasm, and with the low-density area on CT could be found in the A2 and M1 territories. Decrease of cisternal blood measured by CT after the operation did not relate directly to the reduction of vasospasm. When the SAH was Grade II or III in the basal frontal IHF, the angiographic vasospasm grades at the A2 were significantly lower in patients with surgery via the interhemispheric approach than in those with surgery via the pterional approach. Symptomatic vasospasm occurred in two of the eight cases operated on by the interhemispheric approach compared with 11 of the 22 cases approached via the pterional route. In patients with a pterional approach, there was no significant difference in severity of vasospasm in the M1 territory between the side of approach and the opposite side. No consistent relationship could be found between the time interval from SAH to operation and the severity of vasospasm. While clot removal may ameliorate cerebral vasospasm, its effect per se does not seem to be significant.

Adult↗
PubMed1990

The effect of various treatments on composite materials in bonding with resin cements.

The present study investigated the influence of surface treatments of composite materials using 6% hydrofluoric acid or 2% acidulated phosphate fluoride, the influence of the application of a bonding agent to the surface, and the influence of incremental curing of composite materials on the shear bonding strength between composite materials and resin cements. These results were studied statistically by analyzing variances in three-way classification and by their contributory ratios. The effects of hydrofluoric acids or acidulated phosphate fluorides on the treated surfaces of composite materials, and also the interfaces between composite materials and resin cements were further examined by mean of scanning electron microscopy (SEM). Unlike the controls, surfaces of all specimens treated with hydrofluoric acid or fluoride revealed micro-porous surfaces, but the effect of the surface treatment on the bonding strength was not equal for all the composite materials tested. The application of a bonding agent influenced some composite material, but the incremental curing of composite materials had no influence on bonding with resin cements.

Acidulated Phosphate Fluoride↗
PubMed1990

[Study on porcelain veneer restorations. 2. Influence of hydrofluoric acid on bonding strength at the porcelain-resin interface].

Recently, porcelain veneer restoratives have been introduced to the general practice, and their clinical performances have been confirmed through many longterm clinical investigations. It is expected that porcelain veneer restorations will perform successfully in esthetic, conservative and abhesive dentistry. It is an well known fact that the micro-mechanical bonding strength at the porcelain-resin interface which is achieved through the application of hydrofluoric acid to the porcelain surface is quite a strong bonding mechanism. However, there are very few studies reporting on the acid treatment of porcelain surfaces. The authors have been studying the influence of hydrofluoric acid on porcelain surfaces, and in our previous report we reported, the degrees of corroded porcelain treated with different concentrations of hydrofluoric acid for different durations of application. In the present study, shear bonding strength was measured between resin cements and porcelain surfaces treated with different concentrations (4, 6, 8%) of hydrofluoric acid and for different durations (1 to 24 min.), and the appropriate treatment of porcelain surfaces with regard to the bonding strength was determined. The results obtained were as follows. 1. As the treating time increased with any concentration (4, 6, 8%) of hydrofluoric acid, corrosion of the porcelain surface became more intense. Hardly any evidence of corrosion was observed on any porcelain surface treated for one minute, so it seems that the treatment of porcelain surfaces using 4 to 8% hydrofluoric acids should be continued for over three minutes. 2. Observation of the surface profile by SEM showed no significant differences between the surfaces treated for 3, 6, 12 and 24 minutes. 3. It was not clear as to how the differences of hydrofluoric acid concentrations (4, 6, 8%) plus the differences in the kinds of porcelain (Super Porcelain AAA, NORITAKE Co. Ltd., VMK 68, Vita Zahnfabrik Gmbh & Co., Cosmotech Porcelain, G-C Co. Ltd.) had affected the differences in the amount of corrosion. 4. Regarding to the shear bonding strength at the porcelain-resin cement interface, in comparison with control specimens which were only sandblasted, about all two to three times higher bonding strength were obtained in specimens treated with any concentration (4, 6, 8%) of hydrofluoric acids and for any duration between 3 to 24 minutes. Specimens treated for one minute were an exception.

Composite Resins↗
PubMed1990

[Study on the porcelain veneer restoration. 3. Effect of various treatments of porcelain surface on the bonding strength at porcelain-resin interface].

In a previous report, observations were made on the apporopriate concentrations of hydrofluoric acid and durations of application in treating porcelain surfaces to improve the bonding strength at the porcelain-resin interface. Particular concentrations and durations were found, such as 4%, 6 min. for Supper Porcelain AAA, 8%, 6 min. for VMK 68, and 6%, 3 min. for Cosmotech Porcelain, and it was clearly shown that hydrofluoric acid treatment was the most effective treatment for porcelain-resin micro-mechanical bonding. However, because of its strong corrosive action, the use of hydrofluoric acid is very dangerous, and it must be handled with extreme care even in the laboratory. Accordingly, there is a need to find a safer and more effective way of treating porcelain surfaces, particularly in the field of interoral repairs to fractured porcelain restoratives by means of porcelain-resin micro-mechanical bonding. In the present study, 2% acidulated phosphate fluoride (APF), which corrodes the surface of porcelain restoratives, PorceLock (PL), which is a 2.5% buffered hydrofluoric acid made by DenMat Co. and a 6% hydrofluoric acid (HF) preparations were applied to the surface of porcelain specimens and the resulting effects on treated porcelain surfaces were examined by means of SEM observations and shear bonding strength tests. The following results were obtained: 1. In comparison with control specimens which were not treated with any acids or fluoride, a much higher bonding strength at the porcelain-resin interface was obtained in the specimens treated with 2% APF, PL and 6% HF. 2. Regarding to SEM observations, both of the specimens treated 6% HF or PL showed extremely micro-porous surfaces.2+ surfaces of the

Acidulated Phosphate Fluoride↗
PubMed1990

[Blastic crisis of primary myelofibrosis associated with multiple myeloblastomas ].

The patient is a 71-year-old female who underwent splenectomy due to splenomegaly 32 months after diagnosed as having primary myelofibrosis. On examination she was found to have massive skin nodules, lymph nodes swelling and an enlarged liver with an abnormal hematologic profile as follows: RBC count 3.68 x 10(6)/microliters; WBC count 151 x 10(3)/microliters with 11% blasts; and platelet count 42 x 10(3)/microliters. The bone marrow aspirate showed a hypocellular marrow with 19.2% blasts. Histological examination of the skin nodules revealed that they were myeloblastomas, thus suggesting leukemic transformation of primary myelofibrosis. Her WBC count dropped to about 20 x 10(3)/microliters through treatment with vindesine, cyclophosphamide, 6-mercaptopurine and prednisolone, but it did not drop further. Treatment with dexamethasone remarkably regressed the myeloblastomas, but she died of heart failure 4 months after diagnosis of leukemic transformation of primary myelofibrosis. The autopsy findings showed the formation of numbers of myeloblastomas in both the systemic fatty tissue and dura mater as well as extramedullary hematopoiesis in liver and lymph nodes. A rapid development of splenomegaly in a patient with primary myelofibrosis seems to be associated with leukemic transformation.

Aged↗
PubMed1990

[A carcinoma of the cecum arising from the orifice of the appendix: a case report].

Reported is the case of a 50-year-old man who was admitted to hospital because of an abdominal pain. A barium enema revealed the shade of a distended, unfilled appendix that had reversed itself on the cecum and the ascending colon, the latter showing compression from the exterior. Further, a colonoscopic examination uncovered a flat, nodular tumor of the cecum that had elevated at the orifice of the vermiform appendix, and 67Ga scintigraphy indicated the uptake at the lower right abdomen. A resected specimen of the tumor showed proliferation in the cecal mucosa at the orifice of the appendix, causing an appendiceal abscess, and the histopathological findings revealed an adenocarcinoma of the cecal mucosa but no malignant transformation of the appendiceal mucosa.

Adenocarcinoma↗
PubMed1990

[Idiopathic plasmacytic lymphadenopathy with polyclonal hyperimmunoglobulinemia (IPL) accompanied with severe thrombocytopenia and interstitial pneumonitis].

A case of generalized lymphadenopathy with severe thrombocytopenia and marked polyclonal hypergammaglobulinemia is reported. A 51-year-old man was admitted to the hospital because of nasal bleeding and generalized lymphadenopathy. Laboratory examination revealed a platelet count of 6,000/microliters, a total protein level of 11.6 g/dl, and a gammaglobulin level of 8.7 g/dl including 6,726 mg/dl IgG, 1,119 mg/dl IgA, 265 mg/dl IgM, 265 mg/dl IgD and 226 IU/ml IgE. Neither definite evidence suggesting viral infection nor an autoimmune disease was found except slightly elevated titers of anti-microsome and anti-thyroglobulin antibodies. The chest X-ray revealed diffuse reticular shadowing suggesting interstitial pneumonitis. The cervical lymph node biopsy revealed massive infiltration by IgG-, IgA-, and IgM-positive plasmocytoid cells in the paracortical T cell areas, but no destruction of normal architecture of lymph node. The treatment with prednisolone resulted in a decrease in the severity of the lymphadenopathy, thrombocytopenia and polyclonal hypergammopathy. He is still well; however, interstitial pneumonitis, mild thrombocytopenia, and polyclonal hypergammopathy have persisted for 4 years. The histological findings in this case are similar to those in the case of Castleman lymphoma of a plasma cell type. Thus, considering the clinical data and clinical course, the diagnosis in this case is likely to be idiopathic plasmacytic lymphadenopathy with polyclonal hyperglobulinemia as a subtype of the plasma cell type of Castleman lymphoma. However, the accompanying interstitial pneumonitis and the severe thrombocytopenia, which was caused by excessive platelet destruction or by the suppression of megakaryocytes by proliferated plasma cells, are unique and are not found in any of the previously reported cases.

Humans↗
PubMed1989

Hemolysis by aliphatic alcohols and saponin measured by the coil planet centrifugation method.

Using the coil planet centrifugation method, the mechanism of hemolysis by alcohols and saponin was investigated. With this technique, erythrocytes are introduced into a gradient of hemolytic agents in saline, which is prepared in a long coiled polyethylene tube. The tube is centrifuged so that the cells move from a low to a high concentration of hemolytic agent. When the cells lyse, they release hemoglobin which remains stationary, and therefore hemolytic potency can be determined spectrophotometrically by the distance the cells move before lysing. We found that alcohols caused hemolysis at a particular concentration, whereas saponin-induced hemolysis was dependent on the amount of saponin accumulated in the environment of the cell. In addition, alcohols with longer carbon chains were more potent hemolytic agents than those with shorter chains, but each additional carbon group produced less of an increase in hemolysis per mole of alcohol. This chain-length dependency is consistent with a previous study on in vivo alcohol-induced hemolysis. The coil planet centrifugation method is also adaptable to comparative studies on the mechanism of other types of hemolysis, such as immune or drug-induced lysis, and to toxicological studies.

Alcohols↗
PubMed1989

Jugular foramen meningioma.

A case of jugular foramen meningioma is presented with a review of the related literature. The value of computed tomography in the diagnosis of the lesion and in the planning of the operative approach is discussed.

Female↗
PubMed1989

Malignant intraventricular meningioma with spinal metastasis through the cerebrospinal fluid.

A 67-year-old man developed a malignant meningioma of the right lateral ventricle at the trigone, for which he underwent total removal of the tumor and local irradiation. Six months after the operation, a spinal tumor developed and subtotal removal of the tumor was made. The spinal tumor was considered to be a metastasis via the cerebrospinal fluid in view of its histologic identity with the primary tumor, histologic findings of malignancy, absence of von Recklinghausen's disease, and lack of tumor attachment to the dura.

Aged↗
PubMed1989

Electrophysiologic effects of flecainide relative to serum and tissue concentrations in rabbits after chronic drug administration.

The effects of chronic treatment with flecainide on the cellular electrophysiology and the relationship of the electrophysiologic effects to serum and myocardial flecainide concentrations were determined in rabbit ventricular myocardium. Two groups of rabbits were administered flecainide at doses of 7.5 mg/kg body weight (dose I) and 20 mg/kg body weight (dose II) intraperitoneally (i.p.) twice daily for 12-14 days; a third group received saline. Serum and myocardial flecainide concentrations with dose II (0.44 +/- 0.15 micrograms/ml and 3.0 +/- 1.4 micrograms/g, respectively) were significantly (p less than 0.01) higher than with dose I (0.19 +/- 0.11 micrograms/ml and 0.81 +/- 0.15 micrograms/g, respectively). At 1.0-Hz stimulation, only the high dose produced significant changes in transmembrane action potentials of right ventricular myocardial fibers, which showed a 17.6% (n = 6, p less than 0.05) decrease in maximal upstroke velocity (Vmax) of phase 0 and 19.5% (n = 6, p less than 0.05) prolongation of effective refractory period (ERP). Repetitive stimuli led to an exponential decline in Vmax with both dosage regimens. The magnitude of Vmax decrease was frequently dependent and was greater with the higher dose. The rate of decrease of Vmax per action potential (AP) during train of stimuli in rabbits treated with dose II was 0.037 +/- 0.012 (n = 5) at 2.0-Hz stimulation, and the recovery time constant from use-dependent block at 4.0-Hz stimulation increased significantly from 12.6 +/- 3.6% decrease in Vmax with the low dose to 35.6 +/- 7.1% decrease with the high dose. The data show that sodium channel inhibition by chronic flecainide administration is a function of dose, serum, and myocardial flecainide concentrations.

Action Potentials↗
PubMed1989

Effects of propafenone on electrical and mechanical activities of single ventricular myocytes isolated from guinea-pig hearts.

1. The effects of propafenone on the transmembrane action potential and sarcomere shortening during twitch contraction were investigated in single ventricular myocytes isolated from guinea-pig hearts. 2. Propafenone at low concentrations (3-5 x 10(-7) M) slightly lengthened action potential duration (APD), but shortened it at higher concentrations. The shortening of APD was accompanied by an attenuation of sarcomere shortening during twitch contraction. 3. Propafenone (greater than 10(-6) M) caused a concentration-dependent decrease in the maximum upstroke velocity (Vmax) of the action potential. In the presence of propafenone (3 x 10(-6) M), trains of stimuli led to an exponential decline in Vmax. A time constant for the recovery of Vmax from the use-dependent block was 4.8 s. 4. In myocytes treated with propafenone (3 x 10(-6) M), the Vmax of test action potentials preceded by the conditioning clamp pulses to 0 mV was progressively decreased by increasing the duration of single clamp pulse or by increasing the number of multiple brief clamp pulses. 5. These findings suggest that propafenone has use-dependent inhibitory action on the sodium channel by binding to the channel during both activated and inactivated states, and that the unbinding rate is comparable to that of Class-I antiarrhythmic drugs with intermediate kinetics. Propafenone may also have an inhibitory action on calcium and potassium channels.

Action Potentials↗
PubMed1989

Electrophysiological effects of OPC-88117, a new antiarrhythmic agent on papillary muscles and single ventricular myocytes isolated from guinea-pig hearts.

1. The effects of OPC-88117, a new antiarrhythmic agent, on transmembrane action potentials were examined in right ventricular papillary muscles and in single ventricular myocytes isolated from guinea-pig hearts. 2. In papillary muscles, OPC-88117 above 3 x 10(-6) M caused a dose-dependent prolongation of action potential duration (APD). 3. OPC-88117 above 3 x 10(-5) M caused a significant decrease in the maximum upstroke velocity (Vmax) of the action potential without affecting the resting membrane potential. The inhibition of Vmax was enhanced at higher stimulation frequencies. 4. In the presence of OPC-88117, trains of stimuli at rates greater than or equal to 1.0 Hz led to a use-dependent inhibition of Vmax with rapid onset. The time constant for the recovery of Vmax from the use-dependent block was 456 ms. 5. The curves relating membrane potential and Vmax were shifted by OPC-88117 to the direction of more negative potentials (9 mV at 10(-4) M). 6. In single ventricular myocytes treated with OPC-88117 (1-3 x 10(-4) M), the Vmax of test action potentials preceded by conditioning clamp pulses to 0 mV was decreased progressively as the clamp pulse duration was prolonged. 7. These findings suggest that the primary electrophysiological effect of OPC-88117 on the cardiac muscle cell is prolongation of APD (Class III action) and that at high concentrations, it may also possess a lignocaine-like sodium channel inhibitory effect (Class I action).

Action Potentials↗