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Biomedical subjects

S Kataoka

Publications and source records attributed to S Kataoka.

At least 109 records · Page 6Linked to original sources
PubMed1991

Turnover of asymmetric unit membranes in the transitional epithelial superficial cells of the rat urinary bladder.

Asymmetric thick unit membranes were observed on the luminal surface, fusiform vesicles, and multivesicular bodies of superficial cells of rat transitional epithelium. When HRP-labeled Ricinus communis lectin (RCA-I) was injected into the rat urinary bladder, RCA-I was deposited along the luminal cell membrane and in some multivesicular bodies, but not in the fusiform vesicles either before or after contraction. When the bladder was sliced by Vibratome and stained with HRP-labeled RCA-I after fixation, RCA-I was observed in many cell organelles, including fusiform vesicles and multivesicular bodies as well as the luminal surface. When small pieces of tissue were stained en-bloc with HRP-labeled RCA-I, RCA-I was found along the luminal cell surface but not in the fusiform vesicles nor the multivesicular bodies. When HRP alone was injected into the bladder, HRP was observed in some multivesicular bodies after contraction but not in the fusiform vesicles. Various lysosomes were observed by electron microscopy. Some were wrapping multivesicular bodies in ringlike fashion, and some contained asymmetric unit membranes. These findings suggest that the asymmetric unit membranes are carried to the luminal cell membrane via the fusiform vesicles and that old luminal cell membranes are removed via the multivesicular bodies to be degraded by lysosomes.

Animals↗
PubMed1991

Studies on the synthesis of compounds related to adenosine 3',5'-cyclic phosphate. IX. Synthesis and cytotoxic effect of adenosine 3',5'-cyclic alkylphosphoramidates.

A series of adenosine 3',5'-cyclic monophosphoramidates (3, cAMP amidates), including long-chain alkyl amidates, were synthesized from adenosine 3',5'-cyclic monophosphate (1, cAMP) by means of a one-pot reaction. This reaction proceeded by the treatment of cAMP tributylammonium salt (2) with phosphorus pentachloride (PCl5) and alkylamine in N,N-dimethylformamide (DMF). Compounds 3 synthesized were investigated to determine their cytotoxic activities on the growth of mouse mastocytoma P-815 cells, mouse mammary tumor FM3A cells, and human mammary tumor ZR-75 cells in culture. It was found that compounds 3h-m showed significant cytotoxic activities against these cell lines, and that cAMP decylamidate (3j) was the most cytotoxic compound (the concentration required for 50% inhibition of cell growth, ID50 = 6.0, 15.0, 2.2 microM, respectively); the antitumor effect on P-815 cells by a total packed cell volume method showed 81.8% inhibition. The cytotoxic activity of 3 increased with the increase in alkyl chain length up to 10 carbon atoms and decreased in compounds having longer alkyl chain.

Adenosine Monophosphate↗
PubMed1991

[Basal experiments of active oxygen generation in urinary polymorphonuclear leukocytes].

Polymorphonuclear leukocytes (PMNs) play an important role in host defense system. Upon interaction with soluble or particulate matter, PMNs generate active oxygen species (AO), which act on killing of bacteria. In urinary tract infection, urinary PMNs are assumed to have bactericidal activity in urine. Basal experiments were studied on the AO generation of urinary PMNs, monitored by mainly the luminol-dependent chemiluminescence. It was indicated that urinary PMNs, isolated from patients with urinary tract infection, generated AO in physiological medium. This activity of urinary PMNs was found to be significantly inhibited rather than that of PMNs in blood, and this suppression was suggested to be time-dependent. PMNs were affected significantly by osmolarity of reaction medium. These changes were associated with intracellular free calcium. PMNs exposed in hyposmotic medium generated AO, just as they were stimulated. However PMNs exposed in hyperosmotic medium did not generate AO. The stimulation-dependent AO generation of PMNs was increased in hyposmotic solution, while in PMNs incubated at 37 degrees C for 60 min in hyposmotic solution, this generation was decreased than controls. On the other hand, the stimulation-dependent generation was decreased in hyperosmotic solution, while incubated in hyperosmotic solution, this generation was increased. These results suggest that ability of urinary PMNs is regulated by urine osmolarity and retaining time or many other factors, however urinary PMNs are primed and maintain bactericidal activity.

Animals↗
PubMed1990

Acute effects of anticonvulsants on brain-stem auditory evoked potentials in rats.

Acute effects of various anticonvulsants on brain-stem auditory evoked potentials (BAEPs) in rats were tested. A high dose of phenytoin abolished all BAEP waves. Carbamazepine increased all 4 wave latencies. Phenobarbital and clonazepam increased the latencies of waves IV and III. Therefore, if BAEPs are to be used as an ancillary test for brain death, the possibility of significant effects of high dosages of anticonvulsants on BAEPs must be considered.

Acoustic Stimulation↗
PubMed1990

Studies on the synthesis of compounds related to adenosine-3',5'-cyclic phosphate. VI. Synthesis and cardiac effects of N6,N6,2'-O-trialkyl-, N6,2'-O-dialkyl-, and 2'-O-alkyladenosine-3',5'-cyclic phosphates.

The alkylation of adenosine-3',5'-cyclic phosphate (cAMP, 1) with alkyl bromides was investigated and various new alkylated cAMP derivatives, N6,N6,2'-O-trialkyl cAMPs (2), N6,2'-O-dialkyl cAMPs (3) and 2'-O-alkyl cAMPs (4), were prepared by a one step reaction without the introduction of a protecting group into 1. Compounds (2) were synthesized from 1 by treatment with alkyl bromides in the presence of NaH or potassium tert-butoxide in dimethyl sulfoxide. Compounds (3) were also synthesized from 1 under conditions similar to those of the synthesis of 2 except for the use of MeONa as a base. Compounds (4) were prepared from 1 by treatment with alkyl bromides in the presence of 18-crown-6 in dioxane-aqueous KOH solution. N6,2'-O-Dibenzyl cAMP (3e) was obtained from 1 by the same method as the preparation of 4. These new alkylated derivatives were evaluated for cardiotonic activity in vitro. Some of them showed weak positive inotropic effects and strong negative chronotropic effects. Thus, the presence of the 2'-hydroxyl group seemed to be essential for the appearance of potent positive inotropic activity caused by cAMP derivatives.

Animals↗
PubMed1990

Studies on the synthesis of compounds related to adenosine 3',5'-cyclic phosphate. VII. Synthesis and cardiac effects of N6,N6-dialkyl adenosine 3',5'-cyclic phosphates.

A series of novel N6,N6-dialkyl adenosine 3',5'-cyclic phosphates N6,N6-dialkyl cAMPs) was synthesized from 2'-O-p-toluenesulfonyl cAMP (2'-O-tosyl cAMP, 2) and tested for inotropic and chronotropic activities in vitro. Treatment of 2 with excess alkyl halides and sodium hydride followed by detosylation with aqueous NaOH readily gave N6,N6-dialkyl cAMPs (3) in good yields. Various N6,N6-dialkyl cAMPs having different alkyl groups at the N6-position (9-12) were prepared by alkylation followed by detosylation of N6-alkyl-2'-O-tosyl cAMPs (4) which were obtained by the reductive alkylation of 2 with aldehydes in the presence of sodium cyanoborohydride in acetic acid or tosylation of N6-methyl cAMP. The mechanism of the detosylation is briefly discussed. Among the N6,N6-dialkylated derivatives, N6,N6-dipentyl (3f) and N6-ethyl-N6-heptyl (10e) derivatives were found to exhibit a potent positive inotropic effect and a weak positive chronotropic effect. The structure-activity relationships for the position and the length of alkyl residue are discussed.

Alkylation↗
PubMed1990

[Stress analysis of bridge abutment teeth with cemented dowels].

Stress analysis of bridge abutment teeth having cemented dowels was conducted using a two-dimensional finite element method. The results obtained are as follows: 1. In fixed-fixed bridges, compressive stress was found concentrated within the dowel, on the mesial side of the dowel apex, and in the distocervical part of the crown. 2. In cantilever bridges, tensile stress was found concentrated in the disto-occlusal and mesiocervical parts of the crown, and along the mesial sides of the root and the dowel. Compressive stress was concentrated in the distocervical part of the crown, along the distal sides of the root and dowel, and on the mesial side of the dowel apex. 3. In comparison with fixed-fixed bridges, stresses were significantly greater in cantilever bridges in the abutment teeth, the dowel, and crown margins. 4. In both fixed and cantilever bridges, stresses increased in relation to the length of the span. The rate of increase was less, however, in fixed-fixed than cantilever bridges.

Dental Abutments↗
PubMed1990

Expression of the beta-cyclodextrin glucanotransferase gene of an alkalophilic Bacillus sp. #1011 in Escherichia coli cells and characterization of the synthesized enzyme.

To express efficiently the gene for extracellular beta-cyclodextrin glucanotransferase (beta-CGTase) of an alkalophilic Bacillus sp. #1011 using the E. coli promoters (tac, trp and PL promoters), three DNA fragments starting from the nucleotide positions +1, -18, and -48 of the translation initiation site of the gene were prepared and they were fused with the promoters. The maximum production of the enzyme, which was located mainly (90%) in the periplasm of the E. coli strain, was observed in the combination of the trp promoter and the beta-CGTase gene starting from the -48 nucleotide position in the presence of the inducer, IAA. The production of the enzyme was increased to 5.5 times that by the E. coli harboring the original plasmid and to approximately 3 times higher than the extracellular production of the enzyme by the parental Bacillus sp. #1011. The properties including the stability and optimum in the high pH range (pH 9) of the extracellular beta-CGTase from the alkalophilic Bacillus was conserved in the periplasmic enzymes of the E. coli cells.

Amino Acid Sequence↗
PubMed1990

[Delayed postanoxic encephalopathy after strangulation--the serial neuroradiological and neurochemical studies].

A 13-year-old boy was the victim of a strangulation attempt. His behavior was normal by the 6th day after the assault. However, from the 7th day, he developed choreoathetosis, dystonia and marked pseudobulbar palsy. CT and T2-weighted MRI at this time revealed a low density and high signal intensity in the region of the bilateral putamen and caudate respectively for the first time. Thereafter, these symptoms and changes in CTs and MRIs subsided gradually over two months. Sequential analysis of CSF for GABA and dopamine during illness revealed reciprocal changes each other with normal recovery. Because of delayed onset of neurological changes, and findings of CSF with reversible symptoms the delayed encephalopathy after strangulation is probably related to biochemical alteration secondary to anoxia in vulnerable basal ganglia.

Adolescent↗
PubMed1990

[Intramedullary spinal cord metastasis documented by MR imaging].

A 63-year-old woman with progressive paraparesis was found to have an intramedullary spinal cord metastasis from the primary rectal cancer. Myelography and post myelography CT showed an enlargement of the spinal cord at level of the sixth to seventh thoracic vertebra. MR imaging disclosed a localized mass in the spinal cord at the same level. T2-weighted images showed an oval high signal intensity area with central low intensity, and gadolinium-DTPA-enhanced T1-weighted images demonstrated a ring enhancement. Histological examination of the spinal cord revealed an intramedullary spinal cord metastasis with intra-tumorous necrosis at T7 to T8 cord level.

Adenocarcinoma↗
PubMed1990

[Purification and chemical characterization of pregnancy-specific beta 1-glycoprotein (SP1)].

A pregnancy-specific beta 1-glycoprotein (SP1) was purified from human placenta using either an ion-exchange column [method I] or an anti-SP1 antibody immunoadsorbent column [method II]. The yields were 5.2% with a total of 1.2 mg per placenta [method I], and 9. 4% with a total of 2.2 mg per placenta [method II], respectively. The physicochemical properties (molecular weight, sedimentation coefficient, amino acid composition etc.) of SP1 purified from human placenta by these methods are essentially the same as those of typical SP1. It is thus apparent from the present results that these SP1 from pregnant serum and human placenta cannot be distinguished immunologically and biochemically.

Amino Acids↗
PubMed1990

[Neuroradiological studies of Wilson's disease by computed tomography and magnetic resonance imaging].

Three cases of Wilson's disease were imaged by computed tomography and magnetic resonance. They were characterized by common findings. CT scan showed atrophy of cerebral cortex, caudate head, midbrain and cerebellum, and areas of low absorption in the caudate head, putamen, globus pallidus, posterior limb of internal capsule, thalamus and midbrain. The T2-weighted MRI imaging demonstrated marked hyperintensity in the putamen, retrolenticular part of internal capsule, thalamus and midbrain. In 2 patients, these high intensity areas were decreased by chelating therapy. Improvement of the increased intensity on T2-weighted images led to the suggestion that the area of marked hyperintensity area might be edema or demyelination rather than neuronal loss or cavitation.

Adolescent↗
PubMed1990

[Bilateral internuclear ophthalmoplegia in association with basilar artery occlusive disease].

A 56 year-old man presented with vertigo and the right sided weakness. Neurological examination revealed a lethargic man with good orientation to three spheres. His neck was supple. He had anisocoria, the right pupil being larger than the left by 1.5 mm with sluggish light reaction bilaterally. He had exotropia of the right eye in primary gaze. The abduction of both eyes were full with terminal horizontal nystagmus. The adduction of both eyes were quite limited in each eye. He had a limited upward gaze with poor convergence. These were interpreted as the syndrome of the medial longitudinal fasciculus (MLF) bilaterally. He had a depressed gag reflex on the right side with tongue deviation to the right. He had a mild weakness of the right side limb and also had the right sided hemihyperesthesia including his face to pain and temperature. Twenty four hours after the onset, the left brachial angiography revealed a complete occlusion of the rostral portion of the basilar artery without visualization of the posterior cerebral and superior cerebellar arteries bilaterally. CT scans three days after the onset revealed a low density area in the mid pons with extension rostrally up to the mesencephalon. Four days later he became quadriplegic with bilateral horizontal gaze palsy. No more internuclear ophthalmoplegia is noted on both sides. The midline location of the MLF in the pons, and the separate blood supplies by different paramedian branches of the basilar artery, form the anatomical explanation for the frequent unilaterality of vascular and bilaterality of demyelinating lesions. Bilateral MLF syndrome has been considered almost pathognomonic of multiple sclerosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Arterial Occlusive Diseases↗