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Biomedical subjects

S Yamamoto

Publications and source records attributed to S Yamamoto.

At least 19 recordsLinked to original sources
PubMed1995

A histologically distinctive interstitial pneumonia induced by overexpression of the interleukin 6, transforming growth factor beta 1, or platelet-derived growth factor B gene.

Interstitial pneumonia is characterized by alveolitis with resulting fibrosis of the interstitium. To determine the relevance of humoral factors in the pathogenesis of interstitial pneumonia, we introduced expression vectors into Wistar rats via the trachea to locally overexpress humoral factors in the lungs. Human interleukin (IL) 6 and IL-6 receptor genes induced lymphocytic alveolitis without marked fibroblast proliferation. In contrast, overexpression of human transforming growth factor beta 1 or human platelet-derived growth factor B gene induced only mild or apparent cellular infiltration in the alveoli, respectively. However, both factors induced significant proliferation of fibroblasts and deposition of collagen fibrils. These histopathologic changes induced by the transforming growth factor beta 1 and platelet-derived growth factor B gene are partly akin to those changes seen in lung tissues from patients with pulmonary fibrosis and markedly contrast with the changes induced by overexpression of the IL-6 and IL-6 receptor genes that mimics lymphocytic interstitial pneumonia.

Adenoviridae↗
PubMed1995

Partial purification and characterization of the porcine brain enzyme hydrolyzing and synthesizing anandamide.

Anandamide (arachidonylethanolamide) is known as an endogenous agonist for cannabinoid receptors. An amidohydrolase, which hydrolyzed anandamide, was solubilized from the microsomal fraction of porcine brain with 1% Triton X-100. The enzyme was partially purified by Phenyl-5PW hydrophobic chromatography to a specific activity of approximately 0.37 mumol/min/mg of protein at 37 degrees C. As assayed with 14C-labeled substrates, the apparent Km value for anandamide was 60 microM, and anandamide was more active than ethanolamides of linoleic, oleic, and palmitic acids. Ceramidase and protease activities were not detected in our enzyme preparation. The purified enzyme also synthesized anandamide from free arachidonic acid in the presence of a high concentration of ethanolamine with a specific activity of about 0.16 mumol/min/mg of protein at 37 degrees C. On the basis of cochromatographies, pH dependence, heat inactivation, and effects of inhibitors such as arachidonyl trifluoromethyl ketone, p-chloromercuribenzoic acid, diisopropyl fluorophosphate, and phenylmethylsulfonyl fluoride, it was suggested that the anandamide amidohydrolase and synthase activities were attributable to a single enzyme protein.

Amidohydrolases↗
PubMed1995

CD14 enhances cellular responses to endotoxin without imparting ligand-specific recognition.

Binding of the lipid A portion of bacterial lipopolysaccharide (LPS) to leukocyte CD14 activates phagocytes and initiates the septic shock syndrome. Two lipid A analogs, lipid IVA and Rhodobacter sphaeroides lipid A (RSLA), have been described as LPS-receptor antagonists when tested with human phagocytes. In contrast, lipid IVA activated murine phagocytes, whereas RSLA was an LPS antagonist. Thus, these compounds displayed a species-specific pharmacology. To determine whether the species specificity of these LPS antagonists occurred as a result of interactions with CD14, the effects of lipid IVA and RSLA were examined by using human, mouse, and hamster cell lines transfected with murine or human CD14 cDNA expression vectors. These transfectants displayed sensitivities to lipid IVA and RSLA that reflected the sensitivities of macrophages of similar genotype (species) and were independent of the source of CD14 cDNA. For example, hamster macrophages and hamster fibroblasts transfected with either mouse or human-derived CD14 cDNA responded to lipid IVA and RSLA as LPS mimetics. Similarly, lipid IVA and RSLA acted as LPS antagonists in human phagocytes and human fibrosarcoma cells transfected with either mouse or human-derived CD14 cDNA. Therefore, the target of these LPS antagonists, which is encoded in the genomes of these cells, is distinct from CD14. Although the expression of CD14 is required for macrophage-like sensitivity to LPS, CD14 cannot discriminate between the lipid A moieties of these agents. We hypothesize that the target of the LPS antagonists is a lipid A recognition protein which functions as a signaling receptor that is triggered after interaction with CD14-bound LPS.

Animals↗
PubMed1995

Suppression of TNF-alpha mRNA expression in LPS-primed macrophages occurs at the level of nuclear factor-kappa B activation, but not at the level of protein kinase C or CD14 expression.

Previously, we reported that preexposure of proteose peptone-elicited murine peritoneal exudate macrophages (P-PEM) to a low dose of LPS suppressed the expression of TNF-alpha mRNA, but not of IL-1 beta mRNA, induced by a second round of LPS exposure. To elucidate the mechanisms underlying this hyporesponsiveness to LPS, we focused on two molecules: nuclear factor (NF)-kappa B and CD14. Activation of NF-kappa B induced by a second round of LPS was suppressed in LPS-primed P-PEM much like the suppression of TNF-alpha mRNA expression. However, protein kinase C (PKC), a candidate as an activator of NF-kappa B, was not desensitized by LPS priming. LPS-induced TNF-alpha production was not affected by depletion of PKC, and LPS could not induce translocation of PKC. CD14 expression showed no significant difference between control and primed P-PEM. In contrast with J774.1 cells and thioglycolate medium-elicited macrophages (T-PEM), P-PEM exhibited serum-independent TNF-alpha production, and a polyclonal Ab to murine CD14 had no inhibitory effect on the LPS-induced TNF-alpha production by P-PEM. These results suggest that priming by LPS causes blockage at an early step, at least before the activation of NF-kappa B, in the LPS signal transduction pathway, but not at the expression of CD14. Our results also suggest that, in P-PEM, in contrast to J774.1 cells and T-PEM, neither PKC nor CD14 is involved in the LPS-induced activation and suppression of TNF-alpha gene expression.

Animals↗
PubMed1995

Delayed herpes zoster pseudodendrites. Polymerase chain reaction detection of viral DNA and a role for antiviral therapy.

BACKGROUND: The late-onset pseudodendrites, delayed corneal mucous plaques, of herpes zoster ophthalmicus are reported to be of mechanical or immune origin and to be worsened by antiviral therapy. OBJECTIVE: To study pseudodendrites to ascertain a viral presence in the lesions and their response to antiviral therapy. DESIGN: Prospective clinical study. SETTING: Outpatient and inpatient hospital-based corneal specialty referral practice; molecular virology laboratory. PATIENTS: Six patients, aged 33 to 89 years, four with delayed herpes zoster ophthalmicus pseudodendrites and two with herpes zoster ophthalmicus neurotrophic ulceration. One patient was immunosuppressed. MAIN OUTCOME MEASURES: Findings from clinical evaluation; polymerase chain reaction assays of lesions and tear film of six patients; polymerase chain reaction and light and electron microscopy of the corneal button from one patient; and the clinical response of four patients to various antiviral drugs. RESULTS: In contrast to reports in the current literature, delayed pseudodendrites may also be infectious, as they are positive for zoster DNA by polymerase chain reaction and appear responsive to certain antiviral therapy. The corneal button from an immunosuppressed patient had mature and immature viral particles in the basal cells within 2 weeks of transplantation. CONCLUSIONS: To our knowledge, this is the first report of viral DNA in delayed zoster pseudodendrites. Recurrent viral infection may play a role in this form of zoster keratopathy and warrant antiviral therapy.

Adult↗
PubMed1995

Anatomy of the sinus node, AV node, and His bundle of the heart of the sperm whale (Physeter macrocephalus), with a note on the absence of an os cordis.

BACKGROUND: Atrioventricular (AV) conduction time in large whales is only slightly greater than in smaller mammals even though their hearts are enormously larger. Little is known of the detailed histology or cytology of the conduction system of large whales. Such knowledge could be useful in defining the nature of cardiac rhythm and conduction of the whale as well as smaller mammals including humans. METHODS: We studied hearts from seven sperm whales. After fixation in formaldehyde and later dissection, specimens were prepared for histological examination. RESULTS: Cell size, histological organization, and innervation of the sperm whale's sinus node, AV node, and His bundle are similar to most mammalian hearts, except the sinus node is substantially larger. There is no central fibrous body between the atrial and ventricular septa, and the whale has no os cordis. Only the upper quarter of the interventricular septum is fully formed; below that there is only a thin layer of fatty connective tissue between the two ventricles. CONCLUSIONS: Given our morphological findings, we believe that the whale's comparatively short AV conduction time may be best explained by the sinus node and AV node functioning as coupled relaxation oscillators. Absence of an os cordis or central fibrous body or strong attachment between the two ventricles may pose both electrophysiological and hemodynamic hazards when the whale is no longer in its normally buoyant aquatic environment.

Animals↗
PubMed1995

The role of gamma delta T cells in priming macrophages to produce tumor necrosis factor-alpha.

The secretion of tumor necrosis factor (TNF)-alpha from macrophages is regulated by both priming and triggering signals. We found that macrophages from mice lacking gamma delta T cells [T cell receptor (TCR) delta-/- mice], which lack the gene encoding the delta chain, produced only small amounts of TNF-alpha in response to lipopolysaccharide (LPS) and showed a reduced level of expression of CD14. Pre-incubation of macrophages from TCR delta-/- mice with gamma delta T cells from their TCR delta +/- littermates restored their capacity to produce TNF-alpha in response to LPS. The priming activity of gamma delta T cells was in part inhibited by neutralizing anti-interferon (IFN)-gamma monoclonal antibodies. Collectively, these results suggest that gamma delta T cells play a role in priming macrophages to a steady state of activation via IFN-gamma secretion, which allows them to produce TNF-alpha when exposed to LPS.

Animals↗
PubMed1995

m-calpain in rat growth plate chondrocyte cultures: its involvement in the matrix mineralization process.

m-Calpain, a Ca(2+)-dependent neutral cysteine proteinase (EC 3.4.22.17), has been demonstrated to be present in the lower hypertrophic zone of the rat growth plate. Using the pelleted culture system as an in vitro model of rat epiphyseal chondrocyte differentiation, we studied m-calpain contents and activities in pelleted cultures during chondrocyte differentiation and the role of m-calpain in the mineralization process. m-Calpain was demonstrated immunohistochemically in epiphyseal chondrocytes, and immunoreactive m-calpain content in cells increased with terminal differentiation into hypertrophic cells. Immunoblotting also showed the association of the increase in m-calpain in cell pellets and in cell culture medium with development of the culture. Ca(2+)-dependent caseinolytic activities of m-calpain extracted from cell pellets and from the medium increased with chondrocyte differentiation, coincident with the increase in enzyme content. The inhibition of m-calpain by the addition of calpastatin, a specific inhibitor of calpain, caused suppression of matrix mineralization in pelleted cultures; the addition of E-64c, a specific inhibitor of cysteine proteinases, during the mineralization stage also caused a significant inhibition of the matrix mineralization. The addition of E-64c resulted in altered composition of proteoglycan monomers and aggregates in cell pellets and in suppression of mineral growth. These findings support an important role of cysteine proteinases, especially m-calpain, in the regulation of the cartilage mineralization process through proteoglycan degradation.

Alkaline Phosphatase↗
PubMed1995

DNase I interaction on muscle Z-line.

The effect of deoxyribonuclease I on muscle Z-line structures was re-examined. Under conditions of deoxyribonuclease I activation (presence of the divalent cation Ca2+ and Mg2+), a deoxyribonuclease I preparation did not affect Z-line structure if phenylmethylsulfonylfluoride, an inhibitor of serine proteases, was also present. In the absence of protease inhibitor, both Z-lines and M-lines were digested, even in the presence of EDTA and EGTA as inhibitors of deoxyribonuclease I. These electron microscopic observations were consistent with the following results from sodium dodecyl sulphate gel electrophoresis: when the protease was inhibited but deoxyribonuclease I was activated, myofibrillar proteins remained essentially intact. However, degradation of proteins in both rabbit psoas and chicken pectoralis myofibrils was observed in the presence of deoxyribonuclease I inhibitors when the protease inhibitor was absent. Our data strongly suggest that the interaction of deoxyribonuclease I with Z-line proteins previously reported is most likely due to contamination of the deoxyribonuclease I fraction by the serine-type proteases.

Animals↗
PubMed1995

A new technique for performing mitral valve repair in a small left atrium.

A simple approach for exposing a difficult mitral valve within a small left atrium is described herein through the report of case. Mobilization of the superior vena cava with direct venous cannulation and extended dissection of the interatrial groove provide excellent mitral valve exposure, even in patients with a small left atrium.

Aged↗
PubMed1995

Successful utilization of a video-assisted thoracic approach to repair Morgagni's hernia: report of a case.

We describe herein the successful utilization of a video-assisted thoracic surgical approach to repair Morgagni's hernia. The patient was a 62-year-old woman in whom a routine chest X-ray had revealed an asymptomatic mass, which was presumed to be a pericardial lipoma or Morgagni's hernia. The video-assisted thoracic surgical approach was combined with a right submammary minithoracotomy to successfully repair the hernia without performing a laparotomy. The patient's postoperative course was uneventful and she was discharged 14 days after surgery. Thus, we believe that video-assisted thoracic surgery may be a useful and effective method for repairing Morgagni's hernia.

Female↗
PubMed1995

Spontaneous spinal subarachnoid hematoma--case report.

BACKGROUND: Spinal subarachnoid hemorrhage is unusual, and rarely results in spinal subarachnoid hematoma because the cerebrospinal fluid tends to dilute the blood and prevent the formation of clots. We describe a patient with spinal subarachnoid hematoma of unusual spontaneous origin. CASE: A 66-year-old female presented with sudden onset of intense back pain with paraplegia. Magnetic resonance imaging demonstrated a mass lesion between T2 and T6, compressing the spinal cord anteriorly. Emergency osteoplastic laminotomy exposed a hematoma in the subarachnoid space from T2 to T6, but no source of the hemorrhage was found. The patient was able to walk by herself about 20 days after the operation. CONCLUSION: The outcome is significantly influenced by the duration between onset and operation, preoperative neurologic status, and rapidity of symptom progression. Therefore, we emphasize the importance of early diagnosis, and rapid and complete operative removal of spinal subarachnoid hematoma in order to achieve the best outcome.

Aged↗
PubMed1995

Frequent mutations of the p53 gene and infrequent H- and K-ras mutations in urinary bladder carcinomas of NON/Shi mice treated with N-butyl-N-(4-hydroxybutyl)nitrosamine.

To elucidate whether common genetic events in human urinary bladder carcinogenesis also occur in rodent models, we investigated the presence of p53, H- and K-ras mutations in 18 urinary bladder carcinomas induced by various concentrations of N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in male NON/Shi mice. Histopathologically, all were invasive, 11 being squamous cell carcinomas (SCCs) and the remaining seven being transitional cell carcinomas (TCCs). Using polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis followed by DNA sequencing, p53, H- and K-ras mutations were observed in 14 (78%; exons 5-7), two (11%; one each on exons 1 and 2) and one (5.6%; exon 1) animals respectively. The frequencies of mutations in p53 exons 5, 6 and 7 were 7 (39%), 4 (22%), and 9 (50%) respectively, and no mutation was found in exon 8. All mutations involved one base-pair substitution with or without amino acid changes and the types of base-pair substitution were random. No evident association was observed between mutation sites and the histological phenotypes. In conclusion, p53 mutations are frequent in BBN-induced mouse invasive urinary bladder tumors, at similar levels to those observed for human high-grade invasive carcinomas, and this plus their distribution suggests their possible participation in this model of urinary bladder carcinogenesis.

Amino Acid Sequence↗
PubMed1995

Failure of genotoxic carcinogens to produce tumors in human skin xenografts transplanted to SCID mice.

Chemical carcinogenesis of human skin was investigated using human skin xenografts (16 full thickness and 48 split thickness skin grafts) transplanted to CB-17-scid (SCID) mice. Topical application of a carcinogen, i.e. 7,12-dimethylbenz[a]anthracene (DMBA), benzo[a]pyrene, methylcholanthrene or N-methyl-N'-nitro-N-nitrosoguanidine, to the human skin xenografts once a week for 25-30 weeks failed to produce skin tumors. Both DMBA application plus UV-B irradiation and alternate applications of the above four carcinogens in combination with UV-B irradiation also failed to produce tumors. All of these treatments induced skin papillomas in skins of host SCID mice. DMBA induced skin papillomas in allogenic CD-1 mouse skin grafts transplanted to SCID mice. These results indicate that susceptibility of human skin to these carcinogenic stimuli is much lower than that of mouse skin.

Animals↗
PubMed1995

Detection of reverse transcriptase by a highly sensitive assay in sera from persons infected with human immunodeficiency virus type 1.

In an ultrasensitive assay for reverse transcriptase (RT), an in vitro-transcribed heteropolymeric RNA sequence was used as a template and polymerase chain reaction (PCR) amplification with Southern blot hybridization served as a detection system for the cDNA reaction product. The assay, called Amp-RT, detected 9 tested retroviruses in unconcentrated culture supernatants diluted 10(2)- to 10(5)-fold. A comparative analysis using human immunodeficiency virus type 1 (HIV-1) revealed that Amp-RT was 100,000 times more sensitive than the standard RT assay, 10,000 times more sensitive than p24 antigen capture and branched DNA assays, and 100 times more sensitive than RT-PCR or TCID50 assays. Analysis of serum specimens from 42 HIV-1-infected persons by Amp-RT showed that 36 samples (85.7%) were RT-positive. In contrast, 41 serum specimens from persons seronegative for HIV-1 and human T lymphotropic virus types I and II were all Amp-RT-negative.

Animals↗
PubMed1995

Carbohydrate structures of the glycoprotein allergen Cry j I from Japanese cedar (Cryptomeria japonica) pollen.

The glycoprotein allergen Cry j I from Japanese cedar (Cryptomeria japonica) pollen was treated with pepsin and glycopeptidase A to release asparagine-linked oligosaccharides. The reducing ends of the oligosaccharides were aminated with the fluorescent reagent 2-aminopyridine. The oligosaccharide derivatives were purified by gel permeation chromatography and reversed-phase HPLC. Their structures were determined by sequential exoglycosidase digestion and 500 MHz 1H-NMR spectroscopy. Four oligosaccharide structures, A, B, C, and D, were identified as the xylose-containing complex-type. They were present at a molar ratio of 8:1:6:1. By amino acid sequence analyses of the tryptic peptides, Asn-170 and Asn-333 of Cry j I were found to carry asparagine-linked oligosaccharides. [formula: see text]

Allergens↗
PubMed1995

Induction of anagen in telogen mouse skin by topical application of FK506, a potent immunosuppressant.

The effect of topical application of FK506 on the normal hair cycle of C57BL/6J mice was investigated. When telogen mice (7 weeks of age) were treated topically with 1 mumol FK506 on days 0 and 3, 50% of the tested mice entered anagen by day 9 and 100% by day 16. With 0.1 mumol of FK506, 50% of the tested mice entered anagen by day 13 and 80% by day 19, indicating that the effect of FK506 is dose dependent. In control mice, a spontaneous shift from telogen to anagen started on day 14, and 30% of the control animals were in anagen at day 19. Histologic studies revealed that FK506 markedly stimulated the skin and thickened it. The depth and size of hair follicles were also markedly increased in FK506-treated skin compared to control skin. The data on hair growth also support the contention that FK506 induces early onset of anagen and stimulates hair growth. The hair growth stimulated by FK506 looked normal and the hairs were of normal length. The hair growth was restricted to the site of application. These results clearly demonstrate that topical application of FK506 induces anagen hair growth in telogen mouse skin and indicate that the hair-growth-stimulating effect of FK506 is due at least in part to its promoting effect on the hair cycle.

Administration, Topical↗