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Biomedical subjects

H Aihara

Publications and source records attributed to H Aihara.

At least 163 records · Page 9Linked to original sources
PubMed1992

Extramedullary plasmacytoma of the thyroid, associated with follicular colonization and stromal deposition of polytypic immunoglobulins and major histocompatibility antigens. Possible categorization in MALT lymphoma.

A 78-year-old woman complaining of a neck mass underwent right hemithyroidectomy. The 7 x 6 cm thyroid tumor consisted predominantly of mildly atypical, epithelial membrane antigen-positive plasma cells and scattered lymphoid follicles. Features of follicular colonization (plasma cell infiltration into germinal centers) were noted. Numerous CD45RO-positive reactive T cells and a smaller number of CD20-positive blast-like B cells were also distributed among the plasma cell infiltrate. IgG, kappa-type monoclonality with J-chain reactivity was identified in the plasma cells, including those in the lymphoid follicles. The association of pre-existing lymphocytic thyroiditis was confirmed histologically in the non-tumorous thyroid tissue. The tumor exhibited deposition of reticulin fiber-rich, amorphous eosinophilic substances, provoking pronounced foreign body reactions. The deposit, polytypically immunoreactive for immunoglobulin gamma-, mu-, kappa- and lambda-chains, beta 2-microglobulin and HLA-DR, was scarcely reactive upon amyloid staining, and consisted ultrastructurally of electron-dense, non-fibrillar material and entrapped collagen fibers. Multiple myeloma was ruled out by laboratory, histologic and clinical examinations. The possible categorization of this extramedullary plasmacytoma of the thyroid within low-grade B cell lymphoma of the mucosa-associated lymphoid tissue (MALT) is discussed.

Aged↗
PubMed1992

[A clinical study of combined therapy of aspoxicillin and ceftazidime on intractable respiratory infections].

Both aspoxicillin (ASPC) and ceftazidime (CAZ) were administered together to 55 patients with intractable respiratory tract infections. ASPC and CAZ were administered at daily doses of 4 g and 2 to 4 g, respectively. Clinical effects were excellent in 11 cases, good in 33, fair in 7 and poor in 4, thus the efficacy rate was 80.0%. Bacteriologically, identified organisms were eradicated in 14 cases out of 21, decreased in 3, exchanged in 2 and unchanged in 2. The eradication rate was 76.2%. As a side effect, diarrhea was found in only one case, and abnormal laboratory test values were observed in 4 cases. However, these adverse reactions were not severe, therefore it was possible to continue the chemotherapy. These results indicate that the combination antimicrobial chemotherapy of ASPC and CAZ is effective against intractable respiratory tract infections.

Adult↗
PubMed1991

Sustained activation of protein kinase C is essential to HL-60 cell differentiation to macrophage.

Although a single dose of phorbol 12-myristate 13-acetate (PMA) allowed HL-60 cells to differentiate to macrophages, a single dose of membrane-permeant diacylglycerol (DAG), 1,2-dioctanoylglycerol (1,2-DiC8), was normally insufficient to differentiate these cells. These cells metabolized 1,2-DiC8 very rapidly, and 1,2-DiC8 available to protein kinase C (PKC) activation was removed from the incubation medium at a rate proportional to cell density. However, increasing the duration of exposure of HL-60 cells to this DAG either by its repeated addition or by decreasing the cell density greatly enhanced their differentiation to macrophages as measured by CD11b expression. During this differentiation induced by DAG, neither measurable translocation nor depletion (down-regulation) of PKC was observed. When the cells were exposed to PMA, on the other hand, some PKC subspecies were instantaneously translocated to membranes and subsequently disappeared very quickly, whereas the alpha-subspecies was decreased to the level of approximately 60% of the resting cell, but thereafter its activity was maintained at a nearly constant level in membranes. After approximately 4 hr, the PKC subspecies, once depleted, reappeared gradually in the membrane fraction. The results suggest that sustained activation of PKC is essential to differentiation of HL-60 cells to macrophages, and depletion of the enzyme is not needed. Perhaps translocation of PKC represents an extreme state of the active form of the enzyme, which may result from PMA action, and the alpha-subspecies presumably plays a key role in HL-60 cell differentiation.

Biological Transport↗
PubMed1991

Inhibition of gastric H+,K(+)-ATPase by the anti-ulcer agent, sofalcone.

Effects of the anti-ulcer agent, sofalcone, on gastric H+,K(+)-ATPase were studied as well as those of other chalcone derivatives, chalcone and sophoradin. These drugs inhibited pig gastric H+,K(+)-ATPase in a dose-dependent manner. They were 5-10-fold less inhibitory toward Na+,K(+)-ATPase than H+,K(+)-ATPase. The potencies of these drugs on the inhibition of enzymes were as follows: sophoradin greater than sofalcone greater than chalcone. Kinetic studies showed that the inhibition of H+,K(+)-ATPase by sofalcone was competitive with respect to ATP and was non-competitive with respect to K+. Sofalcone also inhibited H+,K(+)-ATPase mediated proton transport and reduced the phosphoenzyme level. These results suggest that sofalcone inhibits gastric H+,K(+)-ATPase competitively with ATP at the ATP site and thereby blocks the phosphorylation of the enzyme. This may be the cause of the anti-secretory activity of sofalcone.

Adenosine Triphosphatases↗
PubMed1991

Protective effects of minaprine in infarction produced by occluding middle cerebral artery in stroke-prone spontaneously hypertensive rats.

1. We examined the effects of minaprine on cerebral infarction produced by occluding of unilateral middle cerebral artery (MCA) above the rhinal fissure in stroke-prone spontaneously hypertensive rats (SHRSP). 2. Oral administration of minaprine (60 mg/kg/day) and vehicle were started 30 min after the occlusion of MCA, and continued for 6 days. 3. The brain was dissected out and 36 coronal multiple sections of the whole brain were histologically prepared to determine the location and extension of infarction. 4. The infarcted area produced by the occlusion of MCA was limited to the cerebral cortex. 5. Body weight of the minaprine-treated rats gradually decreased within 4 days after the occlusion of MCA and thereafter increased, whereas in the vehicle-treated rats, there was a gradual decrease during the experimental period. 6. Size of the infarcted area was serially measured, in each section, using a microcomputer imaging device. In all animals with an occluded MCA, there was a typical pattern of ischemic damage. 7. Post-treatment of MCA occluded SHRSP with minaprine resulted in reduction in infarct size, as compared to findings in the vehicle-treated controls. 8. The pharmacological and histopathological effects of minaprine on the progress of cerebral infarction produced by the occlusion of MCA in SHRSP are discussed.

Animals↗
PubMed1991

Electrophysiological effects of CD-349, a dihydropyridine-type calcium antagonist, on goat cardiac Purkinje fibers.

We examined the calcium antagonistic action of CD-349, a dihydropyridine derivative, on goat cardiac Purkinje fibers using the two-microelectrode voltage-clamp method. CD-349 at a concentration of 10(-5) M shortened the action potential duration without changing the maximum rise in the action potential (Vmax) in goat Purkinje fibers. CD-349 at 3 x 10(-7) to 3 x 10(-6) M inhibited the slow inward current (Isi) in a concentration-dependent manner. At the holding potential of -55 mV, CD-349 exerted a tonic block of Isi, and, furthermore, it exerted a use-dependent block at a frequency range of 1 Hz, but it did not exert a use-dependent block at 0.5 and 0.2 Hz. This may be because CD-349 delayed the recovery process from the inactivation of Isi. The amplitude of the block of Isi was larger at the holding potential of -45 mV than at -55 mV. The inactivation curve of Isi shifted toward a negative potential in the presence of CD-349. Nifedipine also exerted a tonic block of Isi. The onset of the action of nifedipine was quicker than that of CD-349 or nitrendipine. A use-dependent block at 1 Hz and delay of the recovery process from inactivation was also observed with nifedipine. The inactivation curve shifted toward the negative potential with nifedipine. On washout of the drugs, the effects of CD-349 or nitrendipine were not readily reversed compared with those of nifedipine. CD-349 had no effect on either inward rectifying (IK1) or delayed outward potassium (IK) or hyperpolarization-activated inward (If) currents. These observations suggest that, in cardiac tissues, CD-349 selectively inhibits the calcium current, presumably by acting on the inactivated channel.

Action Potentials↗
PubMed1991

Time-dependent interaction of a new H2-receptor antagonist, IT-066, with the receptor in the atria of guinea pig.

3-Amino-4-[4-[4-(1-piperidinomethyl)-2-pyridyloxy]-cis-2- butenylamino]-3-cyclobutene-1,2-dione hydrochloride (IT-066) showed a highly potent and long lasting H2-receptor blocking action in guinea pig atria. The inhibitory effect of IT-066 on the histamine-induced positive chronotropic response increased concentration- and time-dependently. A short period of treatment with IT-066 shifted the concentration-response curve of histamine to the right in parallel, without decreasing the maximal response to histamine. With prolongation of the treatment, the concentration-response curve shifted further to the right with time-dependent suppression of the maximal response to histamine. The inhibitory effect of IT-066 was irreversible. The dissociation constant for histamine (KA) was not changed by prolongation of the time of incubation with IT-066. The dissociation constant for IT-066 (KB) was decreased with the prolongation of the treatment. Kinetic analysis of the time-dependent inhibition showed a two-step reaction: the first was reversible and the second was irreversible. Preincubation of the atria with ranitidine, however, protected the H2-receptor from the apparently irreversible antagonism of IT-066. These results suggest that IT-066 has a time-dependent and irreversible interaction with the H2-receptor and that the interaction may be responsible for the potent and long lasting H2-receptor blocking action of IT-066.

Animals↗
PubMed1991

[A case with a diagnosis of apparent functional sylvian aqueductal stenosis].

A case with a presumptive diagnosis of a functional sylvian aqueductal stenosis is presented. The patient was a 64-year-old female, who suffered from progressive gait disturbance and dementia. On admission, CT-scan showed lateral and third ventricular dilatations. The pattern of the ventricular dilatation suggested an aqueductal stenosis. But CT-scan showed no tumorous lesion. RI-cisternography, RI-ventriculography, aqueductgraphy, and continuous monitoring of the intraventricular pressure of the third ventricle were performed in order to make a diagnosis. The results of these examinations led to the following conclusion. "Although there was no apparent mechanical obstruction or stenosis, the presence of circulatory failure of CSF, demonstrated apparent functional stenosis of the aqueduct sylvii." A VP-shunt operation was performed a month after her admission. Her symptoms improved remarkably.

Cerebral Aqueduct↗
PubMed1990

Interaction of the dihydropyridine calcium antagonist, CD-349, with calmodulin.

The characteristics of the binding of the 1,4-dihydropyridine Ca2+ antagonist, 2-nitratopropyl 3-nitratopropyl 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine 3,5-dicarboxylate (CD-349), to calmodulin (CaM) and the effect of CD-349 on the Ca2+/CaM-dependent enzyme, cyclic GMP (cGMP) phosphodiesterase (PDE), were investigated. CD-349 showed a Ca2(+)-dependent binding to CaM, in equilibrium column binding studies. CD-349 inhibited the [3H]CD-349 binding to CaM, at a concentration producing a 50% inhibition (IC50) of 2.4 microM, whereas the CaM antagonist, trifluoperazine hydrochloride (TFP), stimulated the [3H]CD-349 binding to CaM. Scatchard plot analysis of the binding of CD-349 to CaM revealed that the apparent dissociation constant (Kapp) of CD-349 was 2.1 microM and the maximal number of binding sites (Bmax) of CD-349 was 1.0 nmol/nmol CaM. In the presence of TFP, the Kapp and Bmax values of CD-349 binding to CaM were changed to 1.1 microM and 1.5 nmol/nmol CaM respectively. Although the CaM antagonists, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7) and TFP, decreased and increased, respectively, the fluorescence intensity caused by 2-p-toluidinylnaphthalene-6-sulfonic acid (TNS)-CaM binding, CD-349 only slightly decreased the fluorescence of TNS bound CaM. CD-349 inhibited both basal and Ca2+/CaM-activated cGMP PDE activity. However, CaM did not competitively antagonize the CD-349-induced inhibition of the Ca2+/CaM-activated PDE activity. In addition, the kinetic study showed that CD-349 inhibited both basal and Ca2+/CaM-activated cGMP PDE activity, competitively with cGMP, with almost the same inhibition constant (Ki). These results suggest that CD-349 binds to CaM, with Ca2+ dependency, at sites differing from those which bind to the CaM antagonist. The inhibitory activity of CD-349 on Ca2+/CaM-dependent PDE does not seem to be due to a CaM antagonistic action.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1990

Protein kinase C during differentiation of human promyelocytic leukemia cell line, HL-60.

Protein kinase C (PKC) from human promyelocytic leukemia HL-60 cells can be resolved into three fractions (peak, a, b and c) by hydroxyapatite column chromatography. Peak a and c enzymes are indistinguishable from the brain type II PKC having beta (beta I and beta II)-sequence and type III having alpha-sequence, respectively. Peak b enzyme is a previously unidentified PKC subspecies that has enzymological properties subtly different from type I (having gamma-sequence), type II and type III PKC. Upon treatment of HL-60 cells with 1 microM retinoic acid, this peak b enzyme is decreased dramatically within 24 h, whilst peak a enzyme (beta-PKC) is increased, and peak c (alpha-PKC) enzyme is slightly decreased within 48 h. The result implies that the PKC subspecies in HL-60 cells have distinct functions during cell differentiation.

Amino Acid Sequence↗
PubMed1990

H2-receptor antagonism by a novel compound IT-066 assessed from [14C]aminopyrine accumulation in rabbit parietal cells.

The H2-receptor antagonistic activities and properties of IT-066 were investigated in rabbit isolated gastric mucosal cell and were compared with those of famotidine and cimetidine. IT-066 inhibited dose dependently the histamine-stimulated [14C]aminopyrine ([14C]AP) accumulation in parietal cells. The antagonism was unsurmountable. The inhibitory action of IT-066 was enhanced by lengthening of its incubation time with the cells. IT-066 following 30 min preincubation with the parietal cells showed 32 and 1560 times the activity of famotidine and cimetidine, respectively, as an inhibitor of [14C]AP accumulation. The inhibitory activity of IT-066 on the histamine effect remained after repeated washing of the cells while with famotidine and cimetidine the response to histamine was restored after washout of the drugs from the cells. These data indicate that the antagonism of IT-066 on histamine H2-receptors is high and is unsurmountable in the isolated parietal cell model.

Aminopyrine↗