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Biomedical subjects

A Yamanaka

Publications and source records attributed to A Yamanaka.

At least 19 recordsLinked to original sources
PubMed1998

Immunolocalization of prolyl 4-hydroxylase subunits, alpha-smooth muscle actin, and extracellular matrix components in human lens capsules with lens implants.

Lens capsules become fibrotic after the extraction of a cataract. To understand this phenomenon, we evaluated the immunolocalization of prolyl 4-hydroxylase (an enzyme involved in procollagen hydroxylation), and extracellular matrix components and cytoskeletal components in a normal human lens capsule and in others with intraocular lenses. Lens capsules containing intraocular lenses were removed from a patient with proliferative vitreoretinopathy and three with proliferative diabetic retinopathy during vitreous surgery. Two circular sections of the anterior capsules with lens epithelial cells were obtained by anterior capsulotomy during cataract surgery. In addition, a lens capsular bag was obtained immediately after phacoemulsification. The lens capsules were processed for light microscopic immunohistochemical detection of the alpha and beta subunits of prolyl 4-hydroxylase, extracellular matrix components (including collagen types, laminin and cellular fibronectin) or cytoskeletal components (such as cytokeratin, vimentin and alpha-smooth muscle actin). Monolayer lens epithelial cells were seen on the inner surface of the normal anterior capsules. Each intraocular lens was found to be fixed in the capsular bag. Light microscopic immunohistochemistry showed that these proliferating cells expressed vimentin and alpha-smooth muscle actin; in contrast, quiescent lens epithelial cells did not stain for alpha-smooth muscle actin. Marked immunostaining for subunits of prolyl 4-hydroxylase was detected in lens epithelial cells proliferating on the capsules, while no or only faint prolyl 4-hydroxylase immunoreactivity was detected in quiescent lens epithelial cells immediately after phacoemulsification. Collagen types I, III and VI and cellular fibronectin were observed diffusely in accumulated connective tissue on a capsule with an intraocular lens. Type IV collagen immunoreactivity was seen both in the capsules and in the connective tissue accumulation on the capsules. Collagen V and laminin were detected in association with cellular proliferation. Collagen VII and VIII and laminin 5 were not seen. We concluded that during wound healing of the lens capsule after cataract extraction, the lens epithelial cells that proliferate on the inner surface of the capsule transform it into a myofibroblastic phenotype, expressing prolyl 4-hydroxylase and alpha-smooth muscle actin. These proliferating cells are involved in the production of collagen on the lens capsule. This results in a postoperative fibrotic process and contraction of the lens capsule.

Actins↗
PubMed1998

Subretinal administration of tissue-type plasminogen activator to speed the drainage of subretinal hemorrhage.

BACKGROUND: Bleeding into the subretinal space in the vicinity of the macula is associated with age-related macular degeneration or retinal arterial macroaneurysm. The prognosis for restoration of vision is poor in the presence of blood clots. METHODS: Using a simple device composed of three disposable syringes we injected tissue-type plasminogen activator (tPA) into the subretinal space during conventional vitrectomy in six patients to assist the draining of subretinal clots. RESULTS: Four of six patients recovered their visual acuity postoperatively, while visual acuity in the other patients was stabilized. CONCLUSION: Early drainage of subretinal hemorrhage assisted by the introduction of tPA into the subretinal space led to uncomplicated surgery and favorable postoperative results.

Aged↗
PubMed1998

Silk protein, sericin, inhibits lipid peroxidation and tyrosinase activity.

This study provided the first evidence for an antioxidant action of the silk protein sericin by showing that sericin suppressed in vitro lipid peroxidation. Furthermore, sericin was found to inhibit tyrosinase activity. These results suggest that sericin may be a valuable natural ingredient for food and cosmetic industries.

Animals↗
PubMed1998

Characterization of endothelium-dependent relaxation independent of NO and prostaglandins in guinea pig coronary artery.

In the presence of N omega-nitro-L-arginine and indomethacin, acetylcholine (ACh) induced endothelium-dependent relaxation in guinea pig coronary artery preconstricted with 9,11-dideoxy-9 alpha, 11 alpha-epoxymethano prostaglandin F2 alpha. Dexamethasone and arachidonyltrifluoromethyl ketone, inhibitors of phospholipase A2, and 17-octadecynoic acid, an inhibitor of cytochrome P450 epoxygenase, had no effect on the response to ACh. Although proadifen, which is used widely as an inhibitor of cytochrome P450-dependent enzymes, suppressed the ACh-induced relaxation, the drug also inhibited the relaxation induced by cromakalim, a K+ channel opener. In isolated smooth muscle cells of guinea pig coronary artery, proadifen, but not 17-octadecynoic acid, almost abolished delayed rectifier K+ current. Epoxyeicosatrienoic acids failed to relax the artery. Apamin and iberiotoxin, inhibitors of small- and large-conductance Ca(++)-activated K+ channels, respectively, did not affect the relaxation induced by ACh. A combination of charybdotoxin plus apamin, but not iberiotoxin plus apamin, abolished the response. However, the combination of charybdotoxin plus apamin had no effect on ACh-induced increase in intracellular free Ca++ concentration in endothelial cells. These results suggest that epoxyeicosatrienoic acids do not contribute to N omega-nitro-L-arginine/indomethacin-resistant relaxation induced by ACh in the guinea pig coronary artery. The present study also proposes that K+ channels on vascular smooth muscle cells, which both charybdotoxin and apamin must affect for inhibition to occur, are the target for endothelium-derived hyperpolarizing factor.

Acetylcholine↗
PubMed1997

Deposition of extracellular matrix on intraocular lenses in rabbits: an immunohistochemical and transmission electron microscopic study.

BACKGROUND: We examined by transmission electron microscopy the accumulation of extracellular matrix on intraocular lenses (IOLs) implanted experimentally into rabbit eyes, and evaluated the immunolocalization of such extracellular matrix components as collagen types I, III, and IV, and cellular fibronectin on these IOLs. METHODS: Phacoemulsification and aspiration of the crystalline lens were performed and an IOL was implanted into the capsular bag of each eye of each of 16 adult albino rabbits under general anesthesia. After up to 12 weeks, the animals were killed and the IOLs were removed. Specimens were processed for transmission electron microscopy or for immunohistochemical detection collagen types I, III, and IV, and cellular fibronectin. RESULTS: Transmission electron microscopy revealed an accumulation of extracellular matrix between the residual anterior lens capsule and the surface of an IOL explanted 4 weeks after surgery. Collagen types I and III and cellular fibronectin were detected immunohistochemically on each IOL in association with cellular deposits. Type IV collagen-immunoreactive matrix was not seen on the optic portion, but was detected on the haptic portion of one of six IOLs examined. CONCLUSION: Each component of the extracellular matrix that is deposited on the IOL supplies scaffolding for the adhesion and proliferation of cells. These components are considered to be produced by cells such as lens epithelial cells and macrophages that adhere to the IOL surface.

Animals↗
PubMed1997

Deposition of extracellular matrix on silicone intraocular lens implants in rabbits.

PURPOSE: To examine the deposition of extracellular matrix on silicone intraocular lenses (IOLs) implanted experimentally into rabbit eyes by electron microscopy and to determine the immunolocalization of extracellular matrix components, including collagen types and cellular fibronectin, on these IOLs. METHODS: We performed phacoemulsification and aspiration of the crystalline lens and implanted a foldable silicone IOL in the capsular bag of one eye of each of 26 adult albino rabbits under general anesthesia. After 8 weeks the animals were killed and the eyes were enucleated. The silicone IOLs were processed for electron microscopy and for immunohistochemical detection of collagen types I, III, and IV and cellular fibronectin. RESULTS: Electron microscopy revealed deposition of a presumed cell matrix complex on the optic portion of all silicone IOLs, as well as the adhesion of presumed macrophages and foreign-body giant cells. Cellular deposits showed immunoreactivity for cellular fibronectin. Fibrous or membranous deposits exhibited immunoreactivity for cellular fibronectin and collagen types I and III. A few type IV collagen-immunoreactive deposits were also seen. CONCLUSION: Deposits of extracellular matrix components were observed on silicone IOLs. These deposits may form the scaffolding for the adhesion and proliferation of cells. These matrix components appeared to be the products of cells adhering to the surfaces of IOLs, including lens epithelial cells, macrophages and foreign-body giant cells, indicating that the process of granulation was incomplete.

Animals↗
PubMed1997

Cell proliferation on the outer anterior capsule surface after extracapsular lens extraction in rabbits.

PURPOSE: To use light microscopy to evaluate the presence and distribution of cells that proliferate on the outer surface of the anterior capsule after experimental lens extraction in rabbit eyes. SETTING: Research Laboratory, Department of Ophthalmology, Wakayama Medical College, Wakayama, Japan. METHODS: Extracapsular lens extraction, with or without implantation of a poly(methyl methacrylate) intraocular lens, was performed in 10 adult albino rabbits under general anesthesia. Animals were killed 1 month postoperatively. Each eye was embedded in paraffin and examined by light microscopy. RESULTS: A capsular bag composed of the anterior and posterior capsules was observed. Mononuclear cells, presumed to be lens epithelial cells (LECs), had proliferated in the space between the capsules as well as on the outer surface of the anterior capsules, in association with an accumulation of extracellular matrix. CONCLUSION: After lens extraction, LECs migrated to and proliferated on the anterior surface of the anterior capsule.

Animals↗
PubMed1997

Light and scanning electron microscopy of rabbit lens capsules with intraocular lenses.

PURPOSE: To examine postoperative changes in the lens capsules of rabbit eyes after phacoemulsification and aspiration of the crystalline lens and implantation of posterior chamber intraocular lenses (IOLs) using light and scanning electron microscopy. SETTING: Research Laboratory, Department of Ophthalmology, Wakayama Medical College, Japan. METHODS: The crystalline lens was emulsified and aspirated and an IOL implanted in the capsular bag or ciliary sulcus of each eye in adult albino rabbits under general anesthesia. Animals were killed after 4 weeks, and the lens capsules were removed. The specimens were observed under phase-contrast microscopy and processed for light and scanning electron microscopy. RESULTS: Phase-contrast microscopy revealed presumed lens epithelial cells (LECs) on the central posterior capsules in association with regenerating lenticular fibers and Elschnig pearls in the peripheral capsules. Scanning electron microscopy showed the accumulation of fibrous extracellular matrix on the surface of the posterior capsule in eyes in which the IOL was implanted in the ciliary sulcus. Deposition of packed material attached to the surface of IOLs and of Soemmering's ring were observed in eyes with in-the-bag IOL fixation. At a higher magnification, a parallel arrangement of lenticular fibers was seen in the regenerated lens structure on posterior capsules. An identical structure was observed under light microscopy. Outgrowth of presumed LECs from residual anterior lens capsules and adhesion of macrophages and giant cells were observed on the IOL surface. CONCLUSION: Two types of postoperative changes were observed in lens capsules after implantation of IOLs: accumulation of fibrous extracellular matrix and newly formed lenticular fibers. These changes are attributed to the proliferation of LECs and can induce posterior capsule opacification after IOL implantation.

Animals↗
PubMed1997

Local neurogenic regulation of rat hindlimb circulation: CO2-induced release of calcitonin gene-related peptide from sensory nerves.

1. The mechanism of release of calcitonin gene-related peptide (CGRP) from sensory nerves in response to skeletal muscle contraction was investigated in the rat hindlimb in vivo and in vitro. 2. In the anaesthetized rat, sciatic nerve stimulation at 10 Hz for 1 min caused a hyperaemic response in the hindlimb. During the response, partial pressure of CO2 in the venous blood effluent from the hindlimb significantly increased from 43 +/- 3 to 73 +/- 8 mmHg, whereas a small decrease in pH and no appreciable change in partial pressure of O2 were observed. 3. An intra-arterial bolus injection of NaHCO3 (titrated to pH 7.2 with HCl), which elevated PCO2 of the venous blood, caused a sustained increase in regional blood flow of the iliac artery. Capsaicin (0.33 micromol kg(-1), i.a.) and a specific calcitonin gene-related peptide (CGRP) receptor antagonist, CGRP(8-37), (100 nmol kg(-1) min(-1), i.v.) significantly suppressed the hyperaemic response to NaHCO3. Neither ND(omega)-nitro-L-arginine methyl ester (1 micromol kg(-1) min(-1), i.v.) nor indomethacin (5 mg kg(-1), i.v.) affected the response. 4. The serum level of CGRP-like immunoreactivity in the venous blood was significantly increased by a bolus injection of NaHCO3 (pH = 7.2) from 50 +/- 4 to 196 +/- 16 fmol ml(-1). 5. In the isolated hindlimb perfused with Krebs-Ringer solution, a bolus injection of NaHCO3 (pH = 7.2) caused a decrease in perfusion pressure which was composed of two responses, i.e., an initial transient response and a slowly-developing long-lasting one. CGRP(8-37) significantly inhibited the latter response by 73%. 6. These results suggest that CO2 liberated from exercising skeletal muscle activates capsaicin-sensitive perivascular sensory nerves locally, which results in the release of CGRP from their peripheral endings, and then the released peptide causes local vasodilatation.

Animals↗
PubMed1997

Lung cancer associated with Werner's syndrome: a case report and review of the literature.

A 52-year-old male had an abnormal shadow on a chest X-ray film. His parents were first cousins. His father, brother and two sisters had been diagnosed with Werner's syndrome. His lung lesion was diagnosed as lung cancer and right upper lobectomy was carried out. Histopathological examination of the resected specimen revealed bronchiolo-alveolar carcinoma with independent atypical adenomatous hyperplasia in the alveolar zone. The alveolar structures were those seen in aging lungs, suggesting a close relationship between Werner's syndrome and cancer development.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1996

Optical responses evoked by white matter stimulation in rat visual cortical slices and their relation to neural activities.

To characterize optical responses (ORs) evoked by white matter (WM) stimulation in slices of rat visual cortex (VC) stained with voltage sensitive dyes, time course of ORs in each layer was investigated by recording ORs with a linearly aligned photodiode array, and the spatial patterns of the ORs at specified time after stimulation were investigated by a CCD camera in combination with stroboscopic illumination. The ORs recorded by the photodiode array were an increase in absorption at 700 nm and a decrease in the wavelength below 650 nm, suggesting that the ORs were dye related. The ORs were compared with field potentials (FPs) to clarify that neural events were represented by the ORs, and in support of this view, we found that the first order spatial differentials of ORs and that of FPs were in good agreement. We further compared ORs with intracellular responses, and found that the ORs mainly represent postsynaptic potentials (PSPs) of VC neurons except for the deeper part of layer VI, where a component representing action potentials in fibers stimulated directly was observed. The time-lapse imaging of ORs showed that excitation first propagated vertically up to layer I and subsequently in the horizontal direction along layers II-III and V-VI as in previous investigations. Spatio-temporal patterns of ORs under blockade of synaptic transmission were also investigated to reveal activity of fibers evoked by WM stimulation which produced such patterns of propagation.

Action Potentials↗
PubMed1996

Collagen synthesis in lens epithelial cells on capsules containing intraocular lens implants in rabbits: immunolocalization of prolyl 4-hydroxylase.

BACKGROUND: We evaluated ultrastructurally the presence and distribution of lens epithelial cells and extracellular matrix on the posterior capsule after implantation of a silicone or a polymethyl-methacrylate (PMMA) intraocular lens (IOL) in rabbits. The immunolocalization of prolyl 4-hydroxylase, an enzyme involved in procollagen synthesis, was also examined in such cells. METHODS: Anesthetized adult albino rabbits (n = 12) underwent phacoemulsification and aspiration (PEA) of the crystalline lens and implantation of a silicone or a PMMA IOL into the capsular bag of one eye. They were killed by an intravenous overdose of pentobarbital sodium. The lens capsules were processed for transmission electron microscopy and for immunohistochemical detection of the beta-subunit of prolyl 4-hydroxylase. RESULTS: Ultrastructurally, lens epithelial cells on the posterior capsule evidenced an accumulation of collagenous extracellular matrix. Prolyl 4-hydroxylase immunoreactivity was detected in the cytoplasm of cells distributed on the capsules. CONCLUSION: Lens epithelial cells are involved in the production of collagenous matrix on lens capsules after PEA and implantation of IOL, resulting in a fibrotic process of the lens capsule.

Animals↗
PubMed1996

Characterization of polydnavirus-encoded mRNA in parasitized armyworm larvae.

We have isolated five cDNA clones encoding Cotesia kariyai polydnavirus (CkPDV) mRNAs transcribed in parasitized host larvae of Pseudaletia separata. One of the cDNAs encoding the longest 2.0 kb CkPDV mRNA was sequenced and characterized. Southern hybridization analyses using the cloned cDNA as a probe showed that CkPDV mRNA was homologous to one of CkPDV DNA segments, 5.6 kbp DNA segment A. The 2.0-kb mRNA was demonstrated as being expressed in the parasitized host larvae by Northern-blot analyses. When specific host tissues were examined, the 2.0-kb mRNA was detected mainly in haemocytes. This RNA increased in relative abundance after 2 and 4 h post-parasitization when the immune response of host haemocytes appeared compromised.

Amino Acid Sequence↗
PubMed1996

Lens epithelial cell outgrowth and matrix formation on intraocular lenses in rabbit eyes.

PURPOSE: To evaluate the presence and distribution of lens epithelial cells (LECs) and extracellular matrix on intraocular lenses (IOLs) implanted in the capsular bag in rabbit eyes. SETTING: Department of Ophthalmology, Wakayama Medical College, Wakayama, Japan. METHODS: Five adult albino rabbits had phacoemulsification and IOL implantation in both eyes. Two or 11 months later, the animals were killed by intravenous pentobarbital. The IOLs were removed and observed under scanning and transmission electron microscopy. RESULTS: In addition to the macrophages and giant cells on the IOLs, all eyes had a monolayer of flattened cells growing out from the residual anterior lens capsule and a fibrous meshwork of extracellular matrix. Unlike those of a macrophagic origin, these cells had no central cytoplasmic elevation of nuclei and few cell surface microvilli and were considered to be proliferating LECs. CONCLUSION: Lens epithelial cells are involved in the eye's cellular reaction to IOLs and in the formation of extracellular matrix on IOLs. Further study of LEC behavior on IOLs should be done to improve IOL biocompatibility.

Animals↗
PubMed1996

Anomalous systemic arterial supply to normal basal segments of the left lower lobe. A report of two cases.

Two cases of anomalous systemic arterial supply to the basal segments of the lower lobe of the left lung without sequestration are presented. In the first case, the final diagnosis was made during a surgical operation, and lobectomy of the lower lobe of the left lung was performed. In the second case, the preoperative diagnosis made by CT was confirmed by angiography. An anastomosis was performed between the anomalous artery and the pulmonary artery without resection of the basal segments. Six months after surgery, pulmonary angiography showed improved flow of the anastomosed vessel, but little improvement was evidenced in the perfusion scan.

Adult↗
PubMed1996

[Electron microscopic observations on the posterior lens capsule after implantation of a silicone intraocular lens in rabbits].

We performed phacoemulsification and aspiration of the crystalline lens and implanted a silicone intraocular lens in the capsular bag in rabbits. The posterior capsules were then observed under transmission electron microscopy 2 or 4 months after the surgery. Lens epithelial cells proliferated between the posterior capsule and the optic portion of the silicone intraocular lens, accompanied with the accumulation of collagenous extracellular matrix.

Animals↗
PubMed1996

[Solitary plasmacytoma of sternum--a case report and review of the Japanese literature].

A 39-year-old woman complained of anterior chest pain. A lateral chest X-ray film showed destruction of bone in the body of sternum. CT scan showed a soft tissue density within the sternum. Serum protein electropheresis revealed mild monoclonal gammopathy of IgG-kappa, but the urine contained no Bence-Jones protein. A biopsy specimen showed plasmacytoma with cytoplasmic Ig IgG-kappa. Bone scintigraphy and systemic bone roentgenography revealed only the lesion in the sternum. Sternal subtotal resectin was performed. The defect of the anterior chest wall was reconstructed with double folded marlex mesh and pedicles from the major pectoral muscle. Iliac bone marrow aspiration revealed no evidence of myeloma. There was no serum evidence of monoclonal gammopathy two months after the operation. Therefore, the final diagnosis was solitary plasmacytoma of the sternum. It is now 41 months since surgery, and there have been no signs of fecurrence. Long term follow up is necessary in this case.

Adult↗