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Biomedical subjects

S Miyakawa

Publications and source records attributed to S Miyakawa.

At least 19 recordsLinked to original sources
PubMed2003

Long-term implantation of zinc-releasing calcium phosphate ceramics in rabbit femora.

Zinc is an essential trace element that has stimulatory effects on bone formation. Recently, we developed zinc-releasing calcium phosphate ceramics in order to add the pharmacologic effect of zinc to calcium phosphate ceramics. In our previous study, we showed that the optimum zinc content for promoting bone formation was 0.316 wt %. Therefore a zinc composite ceramic of zinc-containing beta-tricalcium phosphate and hydroxyapatite, with a zinc content of 0.316 wt %, was chosen for long-term implantation. Cylindrical rods of the zinc composite ceramic were implanted in rabbit femora for 2 to 60 weeks. Using computer-aided image analysis, a histomorphometric study was carried out to investigate bone formation and resorption around the implants. The control was a composite ceramic of beta-tricalcium phosphate and hydroxyapatite without zinc. The addition of zinc to the implant demonstrated both favorable and unfavorable effects on bone remodeling. The favorable effect was enhanced bone apposition to the implant surface, demonstrated by a significant increase in intramedullary bone apposition rate at 6 weeks and in cortical bone apposition rate at 24 and 60 weeks (p < 0.05). The unfavorable effect was increased bone resorption, demonstrated by a significant increase in medullary cavity area at 60 weeks (p < 0.05). In order to utilize the favorable effect and avoid the unfavorable effect of zinc, either a reduction in zinc content in the zinc composite ceramic or the selection of implantation sites that do not have excessive exposure to bone marrow are required.

Animals↗
PubMed2002

Clinical and histopathological spectrum of cutaneous vasculitis in rheumatoid arthritis.

BACKGROUND: Cutaneous manifestations are the most frequent, and often the initial feature of extra-articular involvement in patients with rheumatoid vasculitis. OBJECTIVES: The purpose of the study was to evaluate the clinical and histological spectrum of cutaneous vasculitis and the associated systemic involvement in patients with rheumatoid vasculitis. METHODS: Among 525 patients with rheumatoid arthritis, 20 tissue specimens with histologically proven cutaneous necrotizing vasculitis from 11 patients were investigated by studying the types and levels of affected vessels and related clinical features. RESULTS: Small-vessel vasculitis identified as dermal necrotizing venulitis was found in 10 patients, clinically characterized by palpable purpura, maculopapular erythema, erythema elevatum diutinum and haemorrhagic blisters. Arteritis histologically resembling cutaneous polyarteritis nodosa, clinically characterized by subcutaneous nodules, livedo reticularis, atrophie blanche and deep ulcers was identified in four patients all with systemic complications. Coexistence of venulitis and arteritis was identified in three patients. Different cutaneous vasculitic manifestations often coexisted and recurred in the same patient. Three patients with systemic complications of mononeuritis multiplex (two of three), interstitial pulmonary fibrosis (two of three) and abdominal microaneurysms (one of three) died within 1 year of onset of the cutaneous vasculitis. Immunofluorescence demonstrated vessel wall deposition of IgM and/or complement in six of the seven patients examined. CONCLUSIONS: Features of cutaneous rheumatoid vasculitis overlapping both the characteristics of cutaneous necrotizing venulitis and cutaneous polyarteritis nodosa together with coexistence of these different type of vasculitis in the same or different lesional skin account for the associated diverse cutaneous vasculitic manifestations. Although dermal venulitis (leucocytoclastic vasculitis) was the most common presentation, the presence of leucocytoclastic vasculitis in rheumatoid patients did not necessarily indicate a favourable prognosis. Associations with mononeuritis multiplex and bowel involvement had a fatal prognosis, while patients with superficial dermal venulitis without other extra-articular involvement may follow a favourable prognosis.

Adult↗
PubMed2002

Coexistence of beta2 microglobulin and lambda light chain in amyloid fibrils of dialysis-unrelated plasma cell dyscrasia-associated systemic amyloidosis.

BACKGROUND: Systemic amyloidosis occurs as a result of amyloid deposition in various tissues. The amyloid fibrils in systemic amyloidosis have been reported to originate from immunoglobulin light chains. OBJECTIVE: We studied the composition of amyloid fibrils from two patients with plasma cell-associated systemic amyloidosis (PASA). METHODS: A double immunofluorescence study of the lesional skin of PASA was undertaken. Amyloid proteins were extracted with distilled water from one case of PASA. RESULTS: The double immunofluorescence study showed that anti-lambda light chain and anti-beta2 microglobulin antibodies mostly reacted with the same area of amyloid deposit. Amyloid deposits from two patients with PASA who had never undergone haemodialysis showed a positive reaction with the antibodies for beta2 microglobulin as well as immunoglobulin lambda light chain. By the use of immunoblot assay of amyloid fibril proteins, polypeptides immunoreactive with antigamma light chain antibody (29 kDa) and with anti-beta2 microglobulin antibody (12 kDa) were detected. CONCLUSIONS: These results indicate that beta2 microglobulin is a component of amyloid fibrils in PASA.

Aged↗
PubMed2000

Stimulatory effect of zinc-releasing calcium phosphate implant on bone formation in rabbit femora.

Although hydroxyapatite (HAP) and tricalcium phosphate (TCP) are currently used as bone graft substitutes or coatings on metallic prostheses because of their excellent biocompatibility and osteoconductivity, they do not stimulate bone formation or inhibit bone resorption. Zinc, an essential trace element in many animals, has a direct specific proliferative effect on osteoblastic cells and has a potent and selective inhibitory effect on osteoclastic bone resorption in vitro. Therefore, zinc-containing beta-tricalcium phosphate (ZnTCP) ceramics and composite ceramics of ZnTCP and HAP (ZnTCP/HAP) were implanted in the femora of New Zealand White rabbits for 4 weeks to promote bone formation. The implants were sintered ceramics with zinc contents of 0 (control), 0.063, 0.316 and 0.633 wt %. Histological and histomorphometrical investigation of the undecalcified sections revealed an increase by 51% (p =.0509) in the area of newly formed bone around the ZnTCP/HAP implants of 0. 316 Zn wt % compared with the control. Plasma zinc concentration was unchanged. An increased bone resorption on the endosteal surface was observed when ZnTCP and ZnTCP/HAP of 0.633 Zn wt % were implanted. To promote bone formation, the optimum zinc content of the calcium phosphate ceramics was therefore 0.316 wt %.

Animals↗
PubMed2000

Elevated interleukin-12 in pseudosynovial fluid in patients with aseptic loosening of hip prosthesis.

Loosening of a prosthesis is a major problem in total joint arthroplasty. To assess levels of cytokines in patients with such loosening, we measured the pseudosynovial fluid concentration of the following cytokines; tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-1beta, IL-4, IL-6, IL-10, IL-12, matrix metalloproteinase (MMP)-1, and MMP-3. We examined the pseudosynovial fluid in patients with a loose hip prosthesis (group A; n = 8) and the synovial fluid in patients with osteoarthritis (OA) of the hip (group B; n = 18) using enzyme-linked immunosorbent assays. The mean concentration of IL-12 was significantly higher in group A than in group B (P < 0.01). Also, we found a significant (P < 0.05) correlation between the concentration of IL-12 and the concentration of MMP-1 in the patients with prosthesis loosening. The concentrations of TNF-alpha, IL-1beta, IL-4, IL-6, IL-10, IFN-gamma, MMP-1, and MMP-3 appeared to be similar in the two groups, although the small number of samples available precluded us from determining that there was no significant difference. The present study is the first to report elevated IL-12 levels in the pseudosynovial fluid of patients with a loose prosthesis. The immunoregulatory effect of IL-12 against wear particles could play an important role in causing loosening of the prosthesis.

Aged↗
PubMed2000

Abiotic synthesis of guanine with high-temperature plasma.

The origin of guanine has been unknown, though there are some reports concerning its abiotic synthesis. We show here that guanine, as well as uracil and cytosine, are synthesized from a 90%N2-10%CO-H2O gas mixture via a complex organic product produced with the high-temperature and rapid quenching technique. This result implies that a large amount of complex organic matter including precursors of bioorganic compounds might have been produced on the primitive earth after cometary impacts.

Carbon Monoxide↗
PubMed1999

Differential regulation of rheumatoid synovial cell interleukin-12 production by tumor necrosis factor alpha and CD40 signals.

OBJECTIVE: To investigate the roles of tumor necrosis factor alpha(TNFalpha) and the CD40-CD154 interaction in interleukin-12 (IL-12) production by rheumatoid synovial cells (SC). METHODS: Levels of IL-12 (p40 and p70) in synovial tissue and culture supernatants of SC from patients with rheumatoid arthritis (RA), osteoarthritis (OA), and ankylosing spondylitis (AS) were assayed by enzyme-linked immunosorbent assay. Effects of anti-CD154 and anti-TNFalpha antibody on spontaneous and lipopolysaccharide (LPS)-stimulated IL-12 production by SC were examined. Effects of immobilized anti-CD3 treatment and depletion of CD4+ T cells on IL-12 production were also tested. CD154 expression by synovial T cells and intracellular IL-12 production during culture were analyzed by flow cytometry. RESULTS: IL-12 p40 and p70 levels in RA synovial tissue and spontaneous IL-12 p40 production by SC from RA patients were significantly higher than the levels in OA and AS patients. Spontaneous IL-12 production by SC from RA patients significantly decreased after depletion of CD4+ T cells from SC or after application of anti-CD154 antibody, but not by treatment with anti-TNFalpha antibody. Anti-CD3 antibody stimulation increased spontaneous IL-12 p40 production and CD154 expression by synovial T cells. The increment of IL-12 p40 production by anti-CD3 was abrogated by anti-CD154 antibody. IL-12 p40 production was also increased by LPS stimulation. LPS-stimulated IL-12 production was inhibited by anti-TNFalpha antibody, but not by T cell depletion and anti-CD154 antibody treatment. The TNFalpha inhibitor rolipram inhibited LPS-stimulated IL-12 p40 production by RA SC more strongly than spontaneous production. TNFalpha restored LPS-stimulated IL-12 production that had been inhibited by rolipram. CONCLUSION: IL-12 production in RA is regulated by 2 different pathways. One pathway is T cell dependent, predominantly through a CD40-CD154 interaction, while the other is T cell independent, mediated through TNFalpha. Inhibition of IL-12 production by interference with CD40-CD154 interaction and TNFalpha production may be a potential therapeutic strategy for treating RA.

Adjuvants, Immunologic↗
PubMed1999

Amino acid synthesis from CO-N2 and CO-N2-H2 gas mixtures via complex organic compounds.

Reaction among hydrogen cyanide (HCN), formaldehyde (H2CO) and ammonia (NH3) are generally considered an important reaction in amino acid synthesis by electric discharge. Precursors of glycine and aspartic acid were, however, synthesized by adding water to metastable complex compounds produced by quenching a CO-N2 high-temperature plasma. In order to investigate effects of water remaining in an experimental vacuum chamber, optical emission spectroscopic and mass spectrometric measurements were conducted with CO-N2 and CO-N2-H2 gas mixtures. Although residual hydrogen atoms were detected in the CO-N2 experiment, the amount of them was much less than that in the CO-N2-H2 experiment.

Amino Acids↗
PubMed1998

Granulomatous mycosis fungoides with small intestinal involvement and a fatal outcome.

We report a case of granulomatous mycosis fungoides that progressed into fatal gastrointestinal involvement 4 years after the onset of skin lesions, despite improvement of the skin lesions in response to a combination of PUVA and systemic interferon-gamma therapy. Histological examination showed Pautrier's microabscesses with granuloma annulare-like features and sarcoidal granuloma formation in the plaque stage, proliferation of blast-transformed atypical lymphocytes with persistent granuloma formation in the tumour stage, and metastatic lesions. A literature review of granulomatous mycosis fungoides revealed that 11 of the 24 reported cases died of the disease, and like our case, seven died within 5 years. We suggest that mycosis fungoides with granulomatous reactions does not indicate a favourable prognosis.

Aged↗
PubMed1998

Attention-regulated activity in human primary visual cortex.

Effects of attention to a local contour of a moving object on the activation of human primary visual cortex (area V1) were examined. Local cerebral oxygenation changes (an index of neuronal activity) in human area V1 were measured with functional magnetic resonance imaging (fMRI) in conditions including the following two: 1) when attention was selectively directed toward one side of a moving wedge (the attention condition) and 2) when the wedges were viewed passively (the passive condition). Activation in area V1 was found to be higher in the attention condition than in the passive condition. To our knowledge, this is the first finding that attention to motion activates as early as area V1. We suggest that attentional activation of area V1 is task dependent.

Attention↗
PubMed1997

Cutaneous vasculitis in Behçet's disease: a clinical and histopathologic study of 20 patients.

BACKGROUND: Despite the frequency of small vessel vasculitis in skin lesions of Behçet's disease (BD), BD is classified as a neutrophilic dermatosis. OBJECTIVE: Our goal was to determine whether the various cutaneous manifestations of BD are secondary to cutaneous vasculitis. METHODS: Twenty-three specimens with histologically proven necrotizing vasculitis from 20 of 42 patients with BD were investigated. RESULTS: The cutaneous vasculitic manifestations were characterized as erythema nodosum-like eruptions, palpable purpura, hemorrhagic blisters, infiltrated erythema, Sweet's syndrome-like eruptions, papulopustular lesions, and extragenital ulcerations. Combinations of various skin lesions were commonly seen in the same patient. Venous vessels in the entire dermis to the subcutis were affected with sparing of arterial vessels from middermis to subcutis. Histologic features included leukocytoclastic vasculitis in seven and lymphocytic vasculitis in 13 patients with extensive to focal localized fibrinoid necrosis of vessel walls. CONCLUSION: Cutaneous vasculitis in BD is predominantly venulitis or phlebitis. Approximately half (48%; 20 of 42) of BD patients with cutaneous lesions had either lymphocytic (31%; 13 of 42) or leukocytoclastic vasculitis (17%; 7 of 42). We suggest that BD be considered as a vasculitis-associated disease separate from the neutrophilic dermatoses.

Adult↗
PubMed1996

Intraductal papillary adenocarcinoma with mucin hypersecretion and coexistent invasive ductal carcinoma of the pancreas with apparent topographic separation.

We report a 66-year-old man who had a cystic intraductal papillary adenocarcinoma containing a papillary adenoma, in the head of the pancreas and a coexistent invasive, well differentiated solid tubular adenocarcinoma in the tail of the pancreas. He was hospitalized with acute epigastralgia. Computed tomography demonstrated a multilocular cystic mass in the head of the pancreas and a solid tumor in the tail. Endoscopic retrograde pancreatography showed mucin secretion from an enlarged papilla of Vater, marked dilatation of the main pancreatic duct in the head and body, cystic dilatation of the uncinate branch, and irregular narrowing of the main pancreatic duct in the tail. Total pancreatectomy was performed. Between the cystic tumor and the solid tumor there was a distance of 4.8 cm of normal pancreatic parenchyma and duct, recognized both grossly and microscopically. The patient died 35 months after the operation. At autopsy, peritonitis carcinomatosa was found in the abdominal cavity. Microscopically, disseminated nodules were also well differentiated tubular adenocarcinoma. The apparent anatomic separation of these two tumors within the pancreas is extremely unusual.

Aged↗
PubMed1996

Estimation of fat absorption with the 13C-trioctanoin breath test after pancreatoduodenectomy or pancreatic head resection.

The aim of this study was to determine if fat absorption is better after pylorus-preserving pancreatoduodenectomy (PPPD) or duodenum-preserving pancreatic head resection (DPPHR) compared with that following pancreatoduodenectomy with gastrectomy (SPD), provided the patients have similar pancreatic exocrine function. Fat absorption was studied using the 13C-trioctanoin breath test in patients who were grouped according to the degree of fibrosis of the pancreatic remnant. The latter was judged by histologically measuring the fibrosis in a transectional wedge of resected pancreas. We evaluated 11 SPD cases, 25 PPPD cases, and 9 DPPHR cases. The 13C excretion rates and cumulative excretion values following DPPHR or PPPD were significantly better than those following SPD. The 13C excretion rates and cumulative values for the patients with > 30% fibrosis of the pancreas were lower than those in patients with < 30% pancreatic fibrosis, regardless of the surgical procedure. The cumulative value in the SPD group, however, was lower than that in the PPPD or DPPHR patients with < 30% pancreatic fibrosis. The results suggested that fat absorption following PPPD or DPPHR is superior to that after SPD in patients with the same fibrotic area of the pancreatic remnant and depends on the degree of fibrosis in the pancreatic remnant.

Absorption↗
PubMed1996

Photoallergic drug eruption due to pyridoxine hydrochloride.

Photoallergy to vitamin B6 is very rare; only a few cases of contact dermatitis and one case of photosensitive dermatitis due to pyritinol have been reported. We report here the first case of photoallergic drug eruption due to pyridoxine hydrochloride. A 71-year-old man developed papulo-squamous erythemata which were confined to sun-exposed sites. Photopatch testing, together with the clinical course, was helpful in reaching the initial diagnosis; this was confirmed by an oral challenge test. Photoallergic drug eruption due to vitamin B6 should be considered a rare cause of photosensitive dermatitis.

Aged↗
PubMed1996

Cefotiam-induced contact urticaria syndrome: an occupational condition in Japanese nurses.

A case of occupational contact urticaria syndrome caused by cefotiam dihydrochloride (CTM) in a Japanese nurse is reported. The patient had become sensitized to CTM through the process of preparing antibiotics 8 months before she developed symptoms. A review of the literature revealed 13 similar cases, all involving Japanese nurses, reported since CTM became available in Japan.

Adult↗