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Biomedical subjects

S Yamada

Publications and source records attributed to S Yamada.

At least 307 records · Page 17Linked to original sources
PubMed2000

Close association between pulmonary disease manifestation in Mycoplasma pneumoniae infection and enhanced local production of interleukin-18 in the lung, independent of gamma interferon.

To investigate pathophysiologies of Mycoplasma pneumoniae infection from an immunological point of view, we measured the levels of interleukin-18 (IL-18) (originally designated gamma interferon [IFN-gamma]-inducing factor) in 19 serum samples from 10 patients with pneumonia without pleural effusion (ages 1 to 16 years), 3 serum and 13 pleural fluid samples from 11 patients with pleural effusions (ages 11 months to 15 years), and 18 serum and 27 cerebrospinal fluid samples from 24 patients with central nervous system complications (ages 1 to 15 years). IL-18 was measured by a commercially available enzyme-linked immunosorbent assay kit (MBL, Nagoya, Japan). In addition, the levels of tumor necrosis factor alpha, IFN-gamma, IL-6, IL-12, and KL-6 (a mucin-like glycoprotein expressed on type 2 pneumocytes) were measured in selected samples. The results concerning pleural effusions showed that elevated levels of IL-18 in pleural fluid, but not in serum, were solely associated with a sustained fibrotic change of the lung on chest roentgenography which might represent a pathological feature of intraluminal organization. All the pleural fluid samples with elevated levels of IL-18 were positive by PCR for M. pneumoniae DNA. There was no association between IL-18 and IFN-gamma levels in serum or in the pleural fluid. On the other hand, elevated levels of IL-18 in serum, but not in cerebrospinal fluid samples, were observed in the cases complicated by central nervous system involvement, including profound brain dysfunction with seizures. Our study demonstrated that M. pneumoniae can induce IL-18 and that the enhanced local production of IL-18 in the lung is closely associated with pulmonary disease manifestation.

Adolescent↗
PubMed2000

Long-term administration of oral low-dose topoisomerase II inhibitors, MST-16 and VP-16, for refractory or relapsed non-Hodgkin's lymphoma.

It is known that the topoisomerase II inhibitors, MST-16 (sobuzoxane) and VP-16 (etoposide), are effective for the treatment of lymphoma. Five patients with refractory or relapsed non-Hodgkin's lymphoma (NHL) were treated with a combination of oral MST-16 and VP-16 over a long period. Two patients had severely refractory NHL. The remaining 3 patients could not be treated with intensive chemotherapy because of severe organ dysfunction or a poor hematopoietic reserve. All 5 are alive and well after MST-16 and VP-16 treatment. MST-16 and VP-16 are effective for NHL when intensive chemotherapy is ineffective or contraindicated.

Administration, Oral↗
PubMed2000

New imaging findings in a patient with central nervous system dysfunction after bone marrow transplantation.

Central nervous system disorders are an important complication of bone marrow transplantation (BMT). We have recently performed cerebral angiography to examine central nervous system dysfunction in a 22-year-old woman with acute lymphoblastic leukaemia who had undergone BMT. Angiography demonstrated multiple stenoses and occlusions in the peripheral branches of the anterior and middle cerebral arteries, a pattern similar to that seen in vasculitis. She was thought to most likely have cytomegalovirus (CMV) vasculitis, but other forms of vasculitis, such as angiitis-like-syndrome-associated graft-versus-host disease could not be excluded. This case suggests that CMV vasculitis may cause central nervous system dysfunction after BMT and that imaging studies may provide useful information about central nervous system disorders in these patients.

Adult↗
PubMed2000

Clearance of Alzheimer's amyloid-ss(1-40) peptide from brain by LDL receptor-related protein-1 at the blood-brain barrier.

Elimination of amyloid-ss peptide (Ass) from the brain is poorly understood. After intracerebral microinjections in young mice, (125)I-Ass(1-40) was rapidly removed from the brain (t(1/2) </= 25 minutes), mainly by vascular transport across the blood-brain barrier (BBB). The efflux transport system for Ass(1-40) at the BBB was half saturated at 15.3 nM, and the maximal transport capacity was reached between 70 nM and 100 nM. Ass(1-40) clearance was substantially inhibited by the receptor-associated protein, and by antibodies against LDL receptor-related protein-1 (LRP-1) and alpha(2)-macroglobulin (alpha(2)M). As compared to adult wild-type mice, clearance was significantly reduced in young and old apolipoprotein E (apoE) knockout mice, and in old wild-type mice. There was no evidence that Ass was metabolized in brain interstitial fluid and degraded to smaller peptide fragments and amino acids before its transport across the BBB into the circulation. LRP-1, although abundant in brain microvessels in young mice, was downregulated in older animals, and this downregulation correlated with regional Ass accumulation in brains of Alzheimer's disease (AD) patients. We conclude that the BBB removes Ass from the brain largely via age-dependent, LRP-1-mediated transport that is influenced by alpha(2)M and/or apoE, and may be impaired in AD.

Aging↗
PubMed2000

Cloning, characterization, and expression analysis of mouse enamelysin.

Enamelysin is a recently isolated member of the matrix metalloproteinase (MMP) family of extracellular matrix (ECM)-degrading enzymes. Here we describe the isolation and characterization of the mouse enamelysin cDNA. Expression of mouse enamelysin was detectable only in ameloblasts and odontoblasts of developing teeth. Characterization of mouse enamelysin demonstrated that it is highly conserved in both its sequence content and pattern of expression relative to the porcine, human, and bovine homologues previously described.

Amino Acid Sequence↗
PubMed2000

Expression of corticotropin-releasing hormone messenger ribonucleic acid in human pituitary corticotroph adenomas associated with proliferative potential.

Among the factors that promote the growth of human pituitary corticotroph adenomas (hPCAs), the proliferative potential of CRH secreted by hPCAs on these tumors is not well known. In this study, the CRH messenger ribonucleic acid (mRNA) transcripts were demonstrated on paraffin sections using the quantitative in situ hybridization method in 37 of 43 hPCAs, including 17 of 22 microadenomas, 15 of 15 macroadenomas, and 5 of 6 locally invasive adenomas according to Hardy's classification of pituitary adenomas. The more important findings were that CRH mRNA signal intensity in pituitary corticotroph adenoma cells was linearly correlated with Ki-67 tumor growth fractions (r = 0.802; P < 0.0001), and in macroadenoma and locally invasive adenoma cells it was significantly higher than in microadenoma cells (P = 0.035). On the other hand, CRH mRNA transcript accumulation was absent or negligible in 10 normal pituitary glands (P = 0.005). This is the first report of the frequent expression of CRH mRNA localized in human pituitary corticotroph adenoma cells. These results indicate that CRH from a local source of corticotroph adenoma cells not only has autocrine/paracrine functions in corticotroph adenomatous tissue, but also is an important factor associated with a proliferative potential of hPCAs.

Adenoma↗
PubMed2000

Improvement in the histopathology of hearts from cardiomyopathic BIO TO-2 hamsters following long-term administration of amlodipine and cilnidipine.

The effect of long-term administration of amlodipine and cilnidipine was examined on the histopathology and 1,4-dihydropyridine (DHP) calcium channel antagonist receptors in the left ventricle of BIO TO-2 hamsters, a model of dilated cardiomyopathy (DCM). Oral administration of amlodipine (3 and 10 mg/kg/d, 19 weeks) in 7 week-old BIO TO-2 hamsters produced a significant reduction in calcium deposition and necrosis with little change in the cavity area and fibrosis. A reduction of calcium deposition and necrosis in the myocardium of BIO TO-2 hamsters was also seen following similar administration of cilnidipine (10 mg/kg/d). The long-term administration of amlodipine (3 and 10 mg/kg/d) caused a significant increase (36.6 and 21.7%, respectively) in the Bmax for specific (+)-[3H]PN 200-110 binding in the myocardium from BIO TO-2 hamsters, compared with that in control hamsters. In conclusion, the present study has shown that long-term administration of amlodipine and cilnidipine improves calcium deposition and necrosis in the myocardium from BIO TO-2 hamsters. Thus, these data suggest that both agents may be effective pharmacological treatments of DCM.

Amlodipine↗
PubMed2000

Aldol condensation versus conjugate addition: intramolecular cyclization using a combination of Lewis acid and 1,2-diol.

The reactivity of 3-substituted 4-methyl-4-(3-oxobutyl)-2-cyclohexen-1-ones (1) in the presence of a combination of a Lewis acid and a 1,2-diol was studied. The results suggest several factors that influence 6-membered ring formation, including two types of intramolecular aldol reaction and intramolecular 1,4-addition, due to the C3-substituent, Lewis acid, and the presence of diol. In this study, novel methodology to prepare two types of decalin skeleton could be developed.

Acids↗
PubMed2000

Synthesis of (10Z)- and (10E)-19-fluoro-1alpha,25-dihydroxyvitamin D3: compounds to probe vitamin D conformation in receptor complex by 19F-NMR.

To study the interaction of vitamin D with its receptor by 19F-NMR, (5Z,10Z)- and (5Z,10E)-19-fluoro-1alpha,25-dihydroxyvitamin D3 were synthesized starting from vitamin D2 via electrophilic fluorination of vitamin D-SO2 adducts as the key step. Regio- and stereoselective electrophilic fluorination at C(19) of vitamin D-SO2 adducts was achieved under the conditions using (PhSO2)2NF and bulky bases. The stereochemistry of the addition and elimination of SO2 of various vitamin D derivatives was studied in detail. SO2 causes Z-E isomerization of the 5,6-double bond of vitamin D and adds to the resulting (5E)-isomer from the sterically less hindered side opposite to the substituent at C(1). Elimination of SO2 from 19-substituted vitamin D-SO2 adducts proceeded exclusively in a suprafacial manner with respect to the diene part under either thermal or reductive conditions. Dye-sensitized photochemical isomerization of 19-fluorovitamin D derivatives was studied in detail. The rapid isomerization at the 5,6-double bond was followed by the slow isomerization at the 10,19-double bond to yield the (5E,10Z)-isomer (by nomenclature of the 1-OH derivatives) as the major product. (10Z)- and (10E)-19-Fluorovitamin Ds were also interconverted thermally probably via the corresponding previtamin D by 1,7-sigmatropic isomerization.

Fluorine↗
PubMed2000

Insight into acid-mediated asymmetric spirocyclization in the presence of a chiral diol.

Asymmetric spirocyclization based on intramolecular conjugate addition using a combination of a Lewis acid and an optically active cyclohexane-1,2-diol has been studied in connection with 1) the effect of substituents on the cyclohexane-1,2-diol and 2) the effect of substituents on the substrate. This reaction was found to be both thermodynamically and kinetically controlled under restricted conditions.

Acids↗
PubMed2000

Dietary fructooligosaccharides prevent a reduction of cortical and trabecular bone following total gastrectomy in rats.

Fructooligosaccharides (FOS) have been shown to stimulate the absorption of several minerals in the intestine. In the present study, the effects of FOS on osteopenia induced by total gastrectomy were examined. Twenty eight male Sprague Dawley rats were divided into 2 groups: sham-operated (SH) and gastrectomized (GX). After a one-week adaptation period following surgery, the rats were fed synthetic diets with or without 7.5% FOS for 5 weeks. The right femur was then examined by soft X-ray, and the bone mineral density (BMD) was measured. Based on the soft X-ray findings, both cancellous and cortical bone were markedly decreased in GX rats, but not in GX + FOS rats. GX rats showed a 30% lower BMD in the metaphysis and a 20% lower BMD in the diaphysis, compared with SH rats (P < 0.01). As assessed by morphometry, significant decreases were observed in cortical bone in the diaphysis and trabecular bone in the distal metaphysis (P < 0.01). On the other hand, dietary FOS completely prevented these changes following gastrectomy. These findings indicate that dietary FOS might contribute to the prevention of bone diseases following gastrectomy.

Animals↗
PubMed2000

Characterization and amino acid sequences of cytochromes c6 from two strains of the green alga Chlorella vulgaris.

Cytochromes c6 from the green algae Chlorella vulgaris CK-5 (CK5cyc6) and C. vulgaris CK-22 (CK22cyc6) were characterized and their amino acid sequences were analyzed. CK5cyc6 had a molecular mass of 9.3 kDa, isoelectric points of 3.0 (reduced) and 3.6 (oxidized), and a redox potential of +362 mV at pH 7.0. CK22cyc6 had a molecular mass of 9.5 kDa, isoelectric points of 2.9 (reduced) and 3.5 (oxidized), and a redox potential of +355 mV at pH 7.0. The absorption spectra of both cytochromes c6 showed 4 maxima in reduced form, and 2 maxima and a weak peak at 695 nm in oxidized form. The pyridine ferrohemochrome spectra indicated that their prosthetic group was heme c. These physicochemical properties were similar to those of other algal cytochromes c6. The amino acids (88 residues) of CK5cyc6 and CK22cyc6 were sequenced and the sequence motif -CXXCH-, which is typical of the heme-binding site of c-type cytochrome, was clearly confirmed in both cytochromes. Twenty-six amino acid residues were substituted, and the similarity score of each of them was 70.45%.

Algal Proteins↗
PubMed2000

Comparative immunohistopathology in pigs infected with highly virulent or less virulent strains of hog cholera virus.

Eight pigs were inoculated subcutaneously with a highly virulent hog cholera virus (HCV) strain ALD. The infected pigs developed severe illness and became moribund on postinoculation day (PID) 7 or PID 10. Histologic lesions were characterized by severe generalized vasculitis, necrosis of lymphocytes, and encephalitis. HCV antigen was detected in crypt tonsilar epithelial cells, macrophages, and reticular endothelial cells of lymphoid tissues. Antigen localization corresponded well with histologic lesions. Five pigs were inoculated with less virulent HCV Kanagawa/74 strain and were euthanatized on PID 30. All five infected pigs recovered from the illness but became stunted. They also had a slight follicular depletion of lymphocytes, histiocytic hyperplasia, and hematopoiesis in the spleen. Less virulent HCV antigen was observed in the tonsils, kidneys, pancreas, adrenal glands, and lungs. Although antigen localization was less associated with histologic lesions, immunoreactivity was stronger than that in the pigs infected with the ALD strain of HCV. An almost complete loss of B lymphocytes was recognized in pigs infected with the ALD strain and was correlated with follicular necrosis in lymphoid tissues. Loss of B lymphocytes was not prominent in the pigs infected with Kanagawa/74 strain. The number of CD4+ and CD8+ T lymphocytes was significantly higher than that in the noninfected control pigs.

Animals↗
PubMed2000

Rapid oscillation of insulin release by the rat pancreatic islets under stringent Ca2+-free conditions.

Oscillation of insulin release by the pancreatic islets was evaluated under stringent Ca(2+)-free conditions for the first time. Isolated single rat islets were exposed to 16.7 mM glucose in the presence of 1.9 mM Ca(2+), or under the stringent Ca(2+)-free conditions (Ca(2+) omission with 1 mM EGTA, 6 microM forskolin and 100 nM phorbol 12-myristate 13-acetate). Fifteen minutes after the initiation of glucose stimulation, effluent was collected at a 6-s interval, insulin was determined in duplicate by a highly sensitive insulin radioimmunoassay, and oscillation and pulsatility of release statistically analyzed. Significant oscillation of insulin release was observed in all islets irrespective of presence and absence of Ca(2+). Significant pulsatility of release was detected in 7 of 11 islets in the presence of Ca(2+) and three of six isl! ets in the absence of Ca(2+). In conclusion, high glucose elicits oscillatory insulin release both in the presence and absence of extracellular Ca(2+).

Animals↗
PubMed2000

A rapid DNA probe method for detection of Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans.

BACKGROUND: The objective of the present study was to develop a rapid DNA probe method for the microbiological detection of periodontitis that can be used in dental clinics. By using the DNA probe, we also investigated the correlation between the occurrence of putative periodontopathic bacteria and clinical parameters. METHODS: This rapid DNA probe method minimizes the use of a water bath for ordinary hybridization and washing in order to shorten the total reaction time. The detection process could be completed within 2 hours. In order to evaluate the clinical application of the DNA probe, subgingival plaque samples were taken from patients with periodontitis before initial therapy. After the therapy, the patients were microbiologically and clinically evaluated. RESULTS: When the DNA probe method was compared with the culture method, the agreement was 88% for Porphyromonas gingivalis and 67% for Actinobacillus actinomycetemcomitans. A statistically significant association was found between the detection of P. gingivalis and probing depth, bleeding on probing (chi2 test: P <0.001, P <0.05). A significant association was also shown between the detection of A. actinomycetemcomitans and probing depth in patients aged 35 or older (chi2 test: P <0.001). The detection rate of A. actinomycetemcomitans was highest in teenagers. At shallow periodontal pocket sites (PD < or =3 mm) in teenagers, no P. gingivalis was found, while 22% of the sites harbored A. actinomycetemcomitans. After the therapy, the frequency of detection of P. gingivalis decreased significantly only in the clinically improved sites (chi2 test: P <0.001). CONCLUSIONS: The rapid DNA probe method appears promising as an efficient tool for rapid clinical detection of periodontopathic bacteria.

Adolescent↗
PubMed2000

Evaluation of the regenerative effect of a 25% doxycycline-loaded biodegradable membrane for guided tissue regeneration.

BACKGROUND: Biodegradable materials have been successfully utilized for guided tissue regeneration (GTR) and local delivery systems (LDS) because they are biocompatible, less cytotoxic, and do not require removal. Several studies have demonstrated that tetracyclines (TCs), when applied topically, stimulated osteogenesis in experimental bone defects. The purpose of this study was to evaluate the regenerative effect of a 25% doxycycline-loaded biodegradable GTR membrane (Doxy-M) in dogs. METHODS: Doxy-M was made by coating the inner surface of a biodegradable membrane (BD-M) with 25% doxycycline. Five male mongrel dogs with 20 created osseous defects were enrolled. The plain BD-M was used as the control membrane. Either Doxy-M or BD-M was applied in 20 randomly selected defects (10 Doxy-M, 10 BD-M) for 12 weeks with the GTR technique. The histometric analysis was evaluated with the following parameters: defect height (DH), apical extension of junctional epithelium (AEJP), new cementum height (NCH), new bone height (NBH), and new bone area (NBA). RESULTS: The Doxy-M-treated defects showed more pronounced new bone formation and less crestal bone resorption than the BD-M-treated defects. There were no statistically significant differences between the two groups in DH, AEJP, and NCH. Statistically significantly larger NBH (P <0.05) and NBA (P<0.005) were seen in the Doxy-M-treated defects. CONCLUSIONS: The results strongly suggest that Doxy-M may have a beneficial effect on osteogenesis to favor periodontal regeneration.

Absorbable Implants↗
PubMed2000

An unusual case of mediastinal lymphadenopathy caused by amyloidosis.

A 71-year-old Japanese female Nagasaki-atomic-bomb survivor was admitted for evaluation of a mediastinal mass. She was infected with human T-cell leukemia virus type I. Histological examination of the biopsy specimen, obtained thoracoscopically from the mass, revealed amyloid lymphadenopathy confirmed by Congo-red staining and electron-microscopic examination. Amyloid deposits and the serum monoclonal peak consisted of immunoglobulin lambda light chains. No atypical cells were detected in bone marrow. The case was diagnosed as an unusual amyloidosis affecting the mediastinal lymph node. No other sites were found to be affected by amyloidosis, although systemic involvement could not be conclusively ruled out.

Aged↗