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Biomedical subjects

K Nakayasu

Publications and source records attributed to K Nakayasu.

At least 73 records · Page 4Linked to original sources
PubMed1990

[Quantitative analysis of collagen fiber in keratoconus].

In order to identify the direct pathogenic factors involved in the stromal thinning of keratoconus, quantitative analysis of keratocytes, collagen fibers and collagen lamellae in keratoconus cornea was performed histologically by light and electron microscopy. Both normal and keratoconus corneas showed a similar cell density of keratocytes in the central stroma, therefore the total number of keratocytes in keratoconus cornea might be smaller than that of controls, because of the thinning of stroma in the keratoconus. The collagen lamellae in keratoconus corneas showed a significant decrease in number compared with controls. There was a direct relationship between the stromal thickness and number of collagen lamellae. On the other hand, there was no statistical significance between normal and keratoconus corneas in terms of the thickness of collagen lamellae. These results suggest that the thinning of the cornea in keratoconus might occur as the result of a defect of some collagen lamellae due to a disorganization during the process of collagen lamellae formation.

Adolescent↗
PubMed1990

Disseminated intravascular coagulation after hepatic resection.

Disseminated intravascular coagulation (DIC) after hepatic resection is a serious complication that leads to a fatal outcome unless prompt treatment is instituted. Between April 1973 and June 1988, DIC occurred postoperatively in 18 of 192 patients who underwent hepatic resection because of a variety of diseases of the liver and biliary tract. The diagnosis was made on the basis of changes in platelet count, fibrinogen level, serum level of fibrin degradation product (FDP), and protamine sulfate test. Heparin was used in an earlier series but has been discontinued because of difficulty in determining the optimal dose in patients undergoing liver resection. Instead, we now use gabexate mesilate, which blocks the coagulation cascade without the aid of antithrombin III and works as an anticoagulant. Fifteen patients had uneventful recoveries, but three died. Two died of aggravation of DIC, which was a result of reoperation performed under the diagnosis of surgical bleeding. The other patient died of liver failure after fever of unknown cause persisted for 4 months. The rationale for the diagnosis and treatment of DIC after liver resection is documented, and the problems involved are discussed.

Anticoagulants↗
PubMed1990

Hepatic resection for hepatocellular carcinoma.

Between July 1973 and September 1988, 119 patients with hepatocellular carcinoma underwent hepatic resection at Keio University Hospital, Tokyo. Hepatic resection was performed not only for patients with liver cirrhosis and obstructive jaundice but also for patients with advanced disease. Eighty (67.2%) of the 119 patients had liver cirrhosis and four patients had obstructive jaundice. Two or more segments of the liver were resected in 56 (47.0%) patients, 29 of whom had liver cirrhosis. Eleven patients died within 30 days after surgery, an operative mortality rate of 9.2%. Seven additional patients could not be discharged from the hospital, resulting in a hospital death rate of 5.9%. Seventeen of these 18 patients had cirrhosis. Selection of patients with sufficient reserve function of the remaining liver portion, caused a great reduction of the incidence of postoperative death. The 5-year actuarial survival rate for the 101 patients who were discharged from the hospital was 39%, and 13 patients lived longer than 5 years, the longest survival period being 13 years 10 months. Hepatocellular carcinoma is amenable to hepatic resection if patients with sufficient reserve function of the liver are selected.

Adolescent↗
PubMed1989

Strong anti-tumor effect of monosialoganglioside specific monoclonal antibody 202: a clinical trial in a cancer patient with melanoma.

Mab 202, a mouse monoclonal IgM antibody which recognizes sialic acid alpha 2----3 galactosyl residue in monosialogangliosides and reacts with human melanoma cells but not with normal cells, was administered to a melanoma patient by either intralesional injection or intravenous infusion. Mab 202 induced regressions of the metastatic tumors without side effects. Histopathologic examination showed remarkable degenerative and necrotic changes in the tumor, around which lymphocytes, eosinophils, plasma cells and macrophages infiltrated. Immunoperoxidase staining revealed Mab 202 binding to melanoma cells. Clinical and pathologic evidence suggested that Mab 202 has cytotoxic effects against melanoma cells. Mab 202 may therefore be useful in the treatment of human malignant melanoma.

Antibodies, Monoclonal↗
PubMed1989

Localization of 3H-proline, 35S-sulfate and 3H-glucosamine in rat cornea following epithelial removal: epithelio-stromal interaction.

Localization of 3H-proline, 35S-sulfate and 3H-glucosamine was studied by autoradiography in the rat cornea following the removal of the epithelium. The three labeling chemicals were injected into the anterior chamber of rats, one chemical in each rat, 24 hours after the removal of the epithelium. Animals were sacrificed at various intervals up to 7 days after the injection. The silver grains of 35S-sulfate incorporated into the re-covered epithelium gradually shifted into the stroma. On the other hand, the 3H-glucosamine tended to move toward the epithelial cell membrane and the superficial layer of the epithelium. The 3H-proline incorporated in the epithelium remained in the cells without movement. These results suggest that the 35S-sulfate in the epithelium shifted into the stroma as 35S-phosphoadenosine-phosphosulfate [35S-PAPS] before sulfation of glycoconjugates occurred in the epithelium. A large amount of 3H-glucosamine was utilized as a component of low-sulfated glycoconjugates in the epithelial cell membrane and other cell-coating substances.

Adenine Nucleotides↗
PubMed1989

[Statistical analysis of Marfan's syndrome].

To evaluate the ocular complications of Marfan's syndrome which cause severe visual disturbance, we retrospectively investigated 104 patients (208 eyes) with Marfan's syndrome. Dislocation of the lens, the most frequent ocular manifestation, was detected in 151 eyes (72.6%). There were 33 eyes with a visual acuity 0.1 or less. In this group, we found retinal detachment in 12 eyes (36.4%) and glaucoma in 5 eyes (15.2%) as the causes of visual disturbance. Among 17 eyes with retinal detachment, 5 eyes (29.4%) had horizontally dislocated lens. On the other hand. The lens dislocation in a downward direction was found in 5 (22.7%) of 22 eyes with glaucoma. No lens dislocation in an upward direction was found in eyes with glaucoma. The incidence of retinal detachment in aphakic eyes (5/31, 16.1%) was higher than that in the phakic group (16/177, 9.0%). In only 2 (3.6%) of 56 eyes, did the lens dislocation become markedly worse during the observation period. From these data, we re-confirmed that retinal detachment and glaucoma are the most important ocular complications of Marfan's syndrome leading to severe visual disturbance. The decision to operate on the dislocated lens should be made cautiously.

Adolescent↗
PubMed1988

Origin of pericytes in neovascularization of rat cornea.

The possible role of keratocytes in the neovascularization of the rat cornea was studied by means of light and electron microscopic autoradiography. The keratocytes were identified by labeling with 3H-thymidine. Subsequently, the neovascularization was induced by application of 5N sodium hydroxide to the cornea. Besides approximately 10% of the keratocytes, some of the wall cells of the new vessels also incorporated 3H-thymidine. Electron microscopic autoradiography showed that the labeled perivascular cell was extramural. Moreover, the cell seemed to secrete multilayer basement membranous material. Therefore, one might describe the labeled perivascular cell as an "adventitial cell" or "extramural pericyte". These data suggest that keratocytes may participate in the formation of neovascularization in the pathological corneal stroma of the rat.

Animals↗
PubMed1988

Stromal changes following removal of epithelium in rat cornea.

Morphologic and metabolic changes were studied in the corneal stroma of the rat eye following denudation of the epithelium. By touching the cornea with a glass slide coated with 10% gelatin the epithelium was removed with minimal trauma to the underlying stroma. The underlying superficial keratocytes degenerated promptly leaving an anterior acellular zone within 12 hours. At 24 hours wandering cells invaded this damaged stroma, coincident with reepithelialization of the surface. This suggests not only an interaction of epithelium and keratocytes but also of epithelium and wandering cells. Repair of the acellular zone began about 24 hours after the denudation. At 48 hours mitotic figures were abundant with vigorous incorporation of the 3H-thymidine in the remaining keratocytes. The acellular zone became repopulated with new stromal cells advancing from the posterior stroma toward the anterior stroma.

Animals↗
PubMed1988

Expression defect of ornithine aminotransferase gene in gyrate atrophy.

A generalized deficiency in the mitochondrial enzyme, ornithine aminotransferase (OAT: EC 2.6.1.13), is the hallmark of gyrate atrophy (GA), a hereditary degenerative disease of the choroid and retina of the eye that leads to blindness. A human OAT cDNA, previously constructed and characterized in our laboratory, and anti-human OAT antibody were used as probes to examine the OAT gene, mRNA and protein of GA patients. A blot analysis of the genomic DNAs, RNAs and proteins of 14 GA patients identified a case with a partial heterozygous deletion of the functional OAT gene located on chromosome 10, no detectable OAT mRNA, and a barely detectable level of OAT antibody-reactive protein. The rest of the cases showed grossly normal OAT gene, mRNA, and variably reduced levels of OAT protein. A restriction fragment length polymorphism (RFLP) was identified in the functional OAT gene sequence with EcoRI which may be useful for prenatal diagnosis of GA. RFLPs were also identified in the OAT-related gene sequences located on the X chromosome with Hind III and Pst I which may potentially show linkage to X-linked retinitis pigmentosa locus. The finding of an OAT gene, mRNA, and protein defect in a GA case constitutes the first real demonstration of the molecular genetic defect of OAT in GA.

Choroid↗
PubMed1987

Idiopathic retroperitoneal fibrosis.

We treated a patient with idiopathic retroperitoneal fibrosis accompanied by right ureteral constriction. Pyelography, ureterography, and abdominal CT scan were pertinent diagnostics. Close collaboration between the surgeon and the urologist is required when attempting to treat such patients.

Humans↗
PubMed1987

[A case report of successful immunochemotherapy of metastatic renal cell carcinoma using UFT and PSK].

The authors have monitored a case of renal cell carcinoma metastatic to the supraclavicular cavity over a twenty-year period following surgical removal of a cancerous kidney. The subject was a 67-year-old male who had his right kidney removed in 1963 because of renal cell carcinoma. In September of 1983, complaints of pain and an enlarged tumor in the left supraclavicular cavity during a physical examination led to a pathological diagnosis of clear cell carcinoma. Although chemotherapy using FT-207+ PSK was ineffective, there was a response to UFT+ PSK therapy which was deemed effective according to the criteria of Koyama and Saito. The findings suggested that UFT was effective in this case.

Aged↗
PubMed1986

Distribution of types I, II, III, IV and V collagen in normal and keratoconus corneas.

By using type-specific antibodies to types I, II, III, IV and V collagens, distribution of distinct types of collagen in normal human cornea as well as keratoconus cornea were examined by indirect immunofluorescence microscopy. In normal human cornea, immunohistochemical evidence supported the previous biochemical finding that type I collagen was the major type of collagen in human corneal stroma. No reaction was observed to anti-type II collagen antibody in the whole cornea. Anti-type III collagen antibody reacted with the corneal stroma in a similar fashion as that of anti-type I collagen antibody. Type IV collagen was observed in the basement membrane of the corneal epithelium and in Descemet's membrane. Anti-type V collagen antibody also reacted with the corneal stroma diffusely. Bowman's membrane was strongly stained only with he anti-type V collagen antibody. For further details of the distribution of type I, type III and V collagens in human corneal stroma, immunoelectron microscopic study was undertaken. The positive reaction products of anti-type I and anti-type III collagen antibodies were located on the collagen fibrils, while that of anti-type V collagen antibody was either on or close to collagen fibrils. In keratoconus cornea, no difference was observed in terms of the distribution of type I, III and V collagens, while the disruptive and excrescent distribution of type IV collagen was noted in the basement membrane of the corneal epithelium.

Antibody Specificity↗