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S Aiba

Publications and source records attributed to S Aiba.

At least 91 records · Page 5Linked to original sources
PubMed1992

Studies on chitosan: 4. Lysozymic hydrolysis of partially N-acetylated chitosans.

The lysozymic digestibility of partially N-acetylated chitosans was studied by measuring the reducing sugars produced and the molecular weights of their hydrolysates. Moderately N-deacetylated chitosans (MDC), obtained by N-deacetylation of chitin under heterogeneous conditions, were about four times more digestible at an early stage than partially N-acetylated chitosans (PAC-H) with similar acetyl content, prepared by N-acetylation of highly N-deacetylated chitosans under homogeneous conditions. The molecular weights of the hydrolysates of MDC decreased rapidly but gradually reached a constant value in contrast to the behaviour of PAC-H. The Km was 0.14 mM for 30% N-acetylated MDC and 0.12 mM for 65% N-acetylated PAC-H although the degree of N-acetylation of the latter was twice as much as the former. These differences were due to the different distribution patterns of N-acetyl groups in two types of the chitosans. MDC with 20-30% acetyl content have the sequences of more than three N-acetyl-D-glucosamine residues but PAC-H with about 30% acetyl content are random-type copolymers of N-acetyl-D-glucosamine and D-glucosamine units. PAC-H with more than 50% acetyl content have the sequences of more than three N-acetyl-D-glucosamine residues.

Acetylation↗
PubMed1992

Dermatofibrosarcoma protuberans is a unique fibrohistiocytic tumour expressing CD34.

Dermatofibrosarcoma protuberans (DFSP) is a slow growing, locally invasive tumour whose differentiation from other fibrohistiocytic tumours sometimes poses serious diagnostic problems. We investigated CD34 expression immunohistologically in various fibrohistiocytic tumours including dermatofibroma, DFSP, malignant fibrous histiocytoma (MFH), infantile myofibromatosis, fibrosarcoma, hypertrophic scar and keloid. Among these, DFSP was unique in that tumour cells themselves expressed CD34, whereas in other tumours. CD34 expression was observed only on vascular endothelial cells amongst the tumour cells. Until now, there have been no reports of useful immunohistological markers for DFSP. CD34 expression by the tumour cells can be an extremely useful marker in establishing a definitive diagnosis of DFSP.

Antigens, CD↗
PubMed1992

Acquisition of a sucrose utilization system in Escherichia coli K-12 derivatives and its application to industry.

An Escherichia coli strain, B-62, that was isolated from a clinical source and was epidemiologically unrelated to E. coli K-12 was the source of chromosomal DNA for a sucrose utilization system (Scr+) in the construction of a plasmid, pST621. The cloned insert of a gene encoding Scr+ in pST621 conferred a sucrose-positive phenotype onto transformed cells of E. coli K-12 derivatives. Sucrase activity of the transformants was as high as that which would correspond to a "gene dosage effect" of a vector plasmid pBR322, whereas the transformants' sucrose uptake activity was always lower than that of E. coli B-62. A region within an XhoI-SacI fragment (3.2 kb) of pBR322-glyA was replaced in the construction of another plasmid, pST5R7, by a fragment (about 2.6 kb) of pST622 containing the gene encoding Scr+. A genetically stable Scr+ derivative of E. coli K-12 was obtained by introducing the gene encoding Scr+ onto E. coli chromosome via homologous recombination between pST5R7 and the chromosome and subsequent plasmid segregation. The use of low-copy-number plasmid RP4 as a cloning vector was also effective for enhancing the stability of Scr+. Tryptophan producers E. coli SGIII1032S, in which the gene encoding Scr+ was cloned onto the chromosome, and E. coli SGIII1032, which carried Scr+ plasmid RP4.5R7, produced from 6% sucrose in shake flasks (33 degrees C, 96 h) 2.3 and 5.7 g of tryptophan per liter, respectively.

Biological Transport, Active↗
PubMed1992

Calcium currents in hearts with persistent truncus arteriosus.

We have used the neural crest model of defective heart development to characterize both L- and T-type Ca2+ currents (ICa,L and ICa,T) in ventricular myocytes from embryonic chick hearts with a severe outflow tract anomaly known as persistent truncus arteriosus (PTA). Because of smaller whole embryo weights but no significant change in the weights of ventricles with PTA, the ventricle to whole embryo weight ratios from hearts with PTA were 61% larger than normal at day 11 of incubation. There was a 51% reduction in the peak magnitude of ICa,L at a test potential of +10 mV (-1.4 vs. -0.7 microA/cm2), whereas ICa,T, a proportionately large fraction of the total Ca2+ current in the embryonic chick ventricle, was unaffected. In comparison to sham-operated controls, ICa,L was otherwise not different. Half-activation occurred at about -1 and -41 mV, whereas half-inactivation occurred at -19 and -61 mV for ICa,L and ICa,T, respectively. The time for half-recovery from inactivation were not different and were 200 and 230 ms for ICa,L and ICa,T, respectively. The time for half-decay of the currents and their responses to BAY K 8644 were also similar in both sham-operated and experimental hearts. Although the dihydropyridine receptor binding experiments suggest that the total number of L-type Ca2+ channels was not different, the results from the physiological experiments indicate that the number of functional L-type channels available for opening and/or the single-channel conductance may be reduced in hearts with PTA. Finally, our results with the neural crest model indicate that it is unlikely that the development of Ca2+ currents is influenced by the onset of cholinergic innervation in the heart.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1992

Annular psoriasiform eruption with lymphocytic infiltration of the epidermis: a variant of acute psoriasis?

Disseminated annular psoriasiform lesions developed over a period of 2 months in a 48-year-old man with no preceding psoriatic history of drug intake, being accompanied by general dullness and arthralgia. Etretinate was effective for both skin eruption and arthralgia; only the latter recurred on its cessation 5 months later. However, histologic features examined by serial sections totally lacked those of pustular psoriasis; there were no neutrophils in the epidermis where massive T lymphocyte infiltration existed instead, in a fashion similar to that of early psoriatic lesions. We differentiated this peculiar annular psoriasiform eruption from the annular erythematous lesions noted in pityriasis rosea, erythema annulare centrifugum, subacute cutaneous lupus erythematosus, annular erythema associated with Sjögren's syndrome and erythema chronicum migrans. It is our speculation that this dermatosis represents a variant of acute psoriasis, rather than annular pustular psoriasis. The histopathologic and immunohistologic findings suggest ongoing cellular immune responses in these lesions where some unknown inhibitory mechanisms might be operative against further production of neutrophil chemotactic factors that usually takes place in psoriatic lesions.

Acute Disease↗
PubMed1992

[Hospital infection and our policy to control].

Since we organized the committee to control hospital infection in April 1980, we have adopted various investigations and strategies. When wide spread of infection caused by Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa was recognized in 1981 our strategies were set up of water faucets with footpedal, frequent to wash of hands and use of disposable paper towels. Investigation of HBV markers revealed that the positive rate of HBV antibody was 21% in scrub and ward nurse group. Vaccination was performed to our HVB antibody negative members to protect them from the infection of HBV antigen. After HBV antigen positive patients were operated, we sterilized the operating room using our ultraviolet ray irradiation apparatus. In 1990, 50 cases infected with MRSA were detected bacteriologically, which occupied 68.5% of all those infected with Staphylococcus aureus. Therefore, we cultured MRSA from nose swabs and investigated numbers of bacteria in the air which were gathered with air sampler in the operating rooms and wards.

Cross Infection↗
PubMed1991

The ability of cultured Langerhans cells to process and present protein antigens is MHC-dependent.

There is controversy regarding the ability of short term (2 to 3 days) cultured epidermal Langerhans cells (cLC) to process and present intact protein Ag to primed T cells. Some studies have shown that cLC are potent APC for both haptens and intact protein Ag, whereas in others cLC have been unable to process and present intact protein Ag. In an attempt to resolve this controversy, we tested the ability of Langerhans cells from several strains of mice to process and present intact protein Ag to T cell clones and T cell hybridomas. We found that both cLC and freshly prepared Langerhans cells from various Iak mice, including BALB.k mice, process and present intact protein antigens (i.e., hen egg lysozyme, cytochrome c, and OVA) to T cells. These functions are retained in cLC cultured for 7 days. In contrast, cLC from Iad mice do not process intact protein Ag, such as hen egg lysozyme and myoglobin, although they can present relevant peptides to specific T cells and are potent stimulators of allogeneic responses. Furthermore, cLC from (Iak x Iad)F1 mice process and present intact protein Ag to Iak-restricted T cells, but not to Iad-restricted T cells. Although cLC that processed and presented intact protein Ag to T cells exhibited enhanced class II MHC expression, they were, on a per cell basis, somewhat less efficient than were fresh Langerhans cells. Finally, we found that if Iad Langerhans cells are pulsed with intact protein Ag and then cultured for 3 days, they are then fully capable of inducing Ag- and MHC-specific T cell proliferation.

Animals↗
PubMed1991

Studies on chitosan: 3. Evidence for the presence of random and block copolymer structures in partially N-acetylated chitosans.

The chemical structures of moderately N-deacetylated chitosans (MDC) derived from chitin under heterogeneous reaction conditions and partially N-acetylated chitosans (PAC) derived from highly N-deacetylated chitosans (HDC) under homogeneous reaction conditions were deduced from the data of the stability of their solutions in alkaline media, the swelling behaviour and X-ray diffraction patterns of their films in connection with the degree of N-acetylation of them. The solutions of PAC with more than 51% acetyl content, which were prepared from HDC by N-acetylation, were stable and remained clear and homogeneous by adding 1.2 equivalents of NaOH. On the contrary the solutions of PAC with more than 52% acetyl content, which were prepared from MDC, became turbid by neutralization with less than 1.15 equivalents of NaOH. The films of PAC prepared from HDC were highly swollen in water. The degree of swelling of the chitosan film with 51% acetyl content, prepared from the 6% acetyl content chitosan, was 121% while that of the 53% acetyl content chitosan, prepared from the 30% acetyl content chitosan, was 28%. From these data it was possible to set up a hypothesis that PAC prepared from HDC were considered as random-type copolymers of N-acetyl-glucosamine and glucosamine units whereas MDC were considered as block-type copolymers.

Acetylation↗
PubMed1990

Phenotypic and functional characteristics of in vivo-activated Langerhans cells.

After short term culture (2 to 3 days), Langerhans cells (LC) exhibit increased class II MHC Ag and become more potent APC than freshly obtained LC in primary allogeneic and syngeneic T cell activation. To determine whether in vivo LC undergo changes similar to cultured LC, we examined the phenotypic and functional characteristics of LC harvested from ear skin of naive mice painted with various haptens and primary irritants. At 24 h after application of 3% trinitrochlorobenzene, LC appear larger and exhibit more intense staining in epidermal sheets using anti-I-A antibodies, and there was a two- to threefold increase in I-A and I-E expression by LC using flow microfluorimetry analysis. CD45 Ag expression was not altered. Flow microfluorimetry profiles showed the presence of two different LC populations based on fluorescence intensity, i.e., one with the same Ia density as nontreated LC and the other (representing 22 to 50% of all LC) with a markedly enhanced Ia density, (i.e., a 10-fold increase in I-A and I-E). This phenotypic change was observed only with haptens, such as trinitrochlorobenzene, dinitrofluorobenzene, oxazolone, and cinnamic aldehyde. In contrast, application of 10 to 30% sodium lauryl sulfate or vehicle controls did not induce this change. Functionally, LC obtained from hapten-painted mice induced a two- to fivefold increase in 3[H]-TdR incorporation by syngeneic or allogeneic T cells, compared to equal numbers of LC from nontreated or vehicle-treated or sodium lauryl sulfate-treated mice. These phenotypic and functional changes that occur in vivo are therefore analogous to those seen when LC are cultured for short periods of time. Thus, activated LC appear in vivo in response to the epicutaneous application of haptens and may represent an essential step in hapten-specific sensitization.

Administration, Topical↗
PubMed1990

Ostial stenosis of the left coronary artery as a sole clinical manifestation of Takayasu's arteritis: a possible cause of unexpected sudden death.

An 11-year-old girl experienced several syncopal attacks and her electrocardiogram showed ST depression with exercise. Ostial stenosis of the left coronary artery was disclosed by the coronary angiography. We suspected the coronary involvement was due to Takayasu's arteritis. On operation, aortitis in the ascending aorta involving ostium of the left coronary artery was observed. Therefore Takayasu's arteritis is considered to be one of the causes of sudden death.

Aortic Arch Syndromes↗
PubMed1990

Erythema induratum of Bazin as a type of tuberculid.

We report three cases of patients with erythema induratum of Bazin who showed extreme tuberculin hypersensitivity reactions and a good therapeutic response to isoniazid. In the first patient satellite lesions with epithelioid granuloma formation developed 3 weeks after injection of purified protein derivative. In the second patient a high fever developed 1 day after injection of purified protein derivative, and the third patient blistered at the injection site; the histopathologic pattern was similar to erythema multiforme. Immunohistologic study of the epithelioid granulomas demonstrated a predominance of Leu-1--bearing, Leu-3a--bearing, and human lymphocyte antigen-DR-expressing cells. We conclude that erythema induratum of Bazin represents a tuberculid caused by heightened delayed-type hypersensitivity to components of tubercle bacilli released from latent foci of infection.

Adult↗
PubMed1990

Autologous mixed lymphocyte reaction is reduced in patients with psoriasis.

The autologous mixed lymphocyte reaction (auto-MLR) was studied to test the interactions between immunocompetent cells in patients with psoriasis. The auto-MLR in 20 patients with psoriasis was significantly lower than in 16 normal controls. Lower values were found in untreated psoriatic patients than in those in remission following treatment. The values in the latter group were significantly lower than in controls and in six patients with atopic dermatitis in remission. The tendency for an increase in the auto-MLR with a decrease in disease activity was further confirmed in five patients studied before and after treatment. In contrast, the allogeneic lymphocyte reaction (allo-MLR) in psoriatics was similar to that in normal controls.

Culture Media↗
PubMed1990

Does single-amino-acid replacement work in favor of or against improvement of the thermostability of immobilized enzyme?

Thermostabilities of kanamycin nucleotidyltransferase and of its mutants that became thermostable, in the free state, because of single-amino-acid replacements were studied after immobilization of the enzymes on cyanogen bromide-activated Sephadex G-200 particles. Lys in place of Gln at position 102 decreased the thermostability of the immobilized enzyme, whereas replacement with other amino acids enhanced it.

Amino Acid Sequence↗
PubMed1989

The interaction of cultured cells with membranes composed of random and block copolypeptides.

Random copolypeptides and block copolypeptides were synthesized, and an interaction between these polypeptide membranes and the cells was studied by a cell culture method (cell line, Ca. 9.22). In random copolypeptides composed of gamma-methyl L-glutamate and gamma-benzyl L-glutamate, cell attachment and cell growth depended on the monomer composition, and showed a maximum at around 70 mole % of benzyl glutamate. Block copolypeptide composed of L-methionine and oxyethylene exhibited low cell attachment and cell growth even at 10 mole % of oxyethylene content, compared to L-methionine homopolymer. ESCA study of the membrane suggested this result to be due to concentration of the poly(oxyethylene) block chain of the polymer on the surface of the membrane. Block copolypeptide composed of N5-(3-hydroxypropyl) L-glutamine and L-leucine exhibited low cell attachment and cell growth, while the corresponding random copolypeptide exhibited high cell attachment and cell growth. This difference is attributable to the microheterophase structure with the hydrophilic domains embedded in the hydrophobic matrix in the block copolypeptide membrane.

Biocompatible Materials↗
PubMed1989

Proliferative responses of peripheral blood mononuclear cells from psoriatic patients to T lymphocyte-stimulating cytokines (IL-2, IL-3, IL-4, and granulocyte-macrophage colony-stimulating factor) and OK-432.

We have examined the effects of four well-characterized cytokines with T lymphocyte-stimulatory activity, i.e., interleukin (IL)-2, IL-3, IL-4, and granulocyte-macrophage colony-stimulating factor (GM-CSF) on [3H]-thymidine incorporation in peripheral blood mononuclear cells (PBMs) obtained from patients with psoriasis. Under the influence of these cytokines, the incorporation of [3H]-thymidine into the PBMs was not different between psoriatic patients and healthy controls either in culture supplemented with pooled AB serum or with autologous serum. However, a potent immunopotentiator OK-432, which is a lyophilized preparation of penicillin-treated low virulence Su-strain of Streptococcus pyogenes group A3, induced significantly less incorporation of [3H]-thymidine into the PBMs from psoriatic patients than those from healthy controls [in both the culture supplemented with pooled AB serum (p less than 0.01) and that with autologous serum (p less than 0.01)]. This reduction in thymidine uptake was closely related to the disease activity as well as to the extent of skin lesions of the psoriatic patients. The defective immune response of PBMs from psoriatic patients to OK-432 probably reflects an abnormality at the level of interaction between monocytes and T cells or at the subsequent production and release of cytokines by them.

Adult↗