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Biomedical subjects

M Kuroki

Publications and source records attributed to M Kuroki.

At least 37 records · Page 2Linked to original sources
PubMed2001

Vasospastic total occlusion at the left main tract in a single coronary artery.

A 64-year-old man was admitted to hospital under the suspicion of unstable angina pectoris. Coronary angiography showed that he has a single coronary artery originating from the right coronary artery (RCA) without significant fixed stenosis. Acetylcholine was superselectively infused into the left main coronary artery (LMCA), and confirmed the coronary vasospastic occlusion associated with chest pain and elevation of the ST-segment in the precordial leads. This is the first report of the induction of a totally occlusive spasm of the LMCA of a patient with a RCA type single coronary artery, and this case suggests that spasm of the aberrant coronary artery is a potential mechanism for sudden death in patients with a single coronary artery.

Angina Pectoris, Variant↗
PubMed2001

Identification and comparison of residues critical for cell-adhesion activities of two neutrophil CD66 antigens, CEACAM6 and CEACAM8.

CEACAM6 (CD66c) and CEACAM8 (CD66b) are cell-adhesion proteins on neutrophils that belong to the human carcinoembryonic antigen (CEA) family. CEACAM6 reveals homophilic adhesion and heterophilic adhesion to other CEACAM family antigens including CEACAM8, CEACAM1, and CEA, whereas CEACAM8 exhibits only heterophilic adhesion to CEACAM6. Here, we investigated and compared structural requirements for the homophilic adhesion of CEACAM6 and heterophilic adhesion between CEACAM6 and CEACAM8 at the amino acid level by using CHO transfectants expressing their mutant and chimeric proteins. The NH(2)-terminal domain (N-domain) of CEACAM6 expressed on a CHO cell was suggested to bind the N-domain of CEACAM6 or CEACAM8 on the opposing cell. By homologue-scanning mutagenesis, we found that the locations of the sequences critical for the adhesion of CEACAM6 to itself and to CEACAM8 are overlapped and that they are highly similar but not identical to the locations of the residues previously shown to be essential for the binding of CEACAM antigens to Opa proteins of pathogenic NEISSERIAE: Our findings imply that subtle differences in the N-domain sequences determine the specificity of the CEACAM antigens on neutrophils for interaction with the same or different CEACAM antigens and the bacterial proteins.

Amino Acid Sequence↗
PubMed2000

Extracellular N-domain alone can mediate specific heterophilic adhesion between members of the carcinoembryonic antigen family, CEACAM6 and CEACAM8.

The domain(s) responsible for the specific heterophilic adhesion between two members of the carcinoembryonic antigen (CEA) family, CEACAM6 and CEACAM8, both of which with three extracellular domains, were investigated using Chinese hamster ovary (CHO) transfectants expressing chimeric antigens. Using a chimeric antigen in which the N-domain, a sole extracellular domain, of CEACAM3 was substituted with that of CEACAM6, it was shown that the N-domain of CEACAM6 alone was able to mediate specific adhesion to CEACAM8. Furthermore, the chimeric antigen was shown to bind significantly to chimeric CEA whose N-domain was substituted with that of CEACAM8, but not to unsubstituted CEA. These results demonstrate that the N-domain alone is sufficient and other domains of CEACAM6 or CEACAM8 are not required for this specific binding. We therefore propose a model of heterophilic interaction between the N-domains, which is distinct from that of CEA-CEA homophilic binding.

Animals↗
PubMed2000

The coupling of 5-oxo-eicosanoid receptors to heterotrimeric G proteins.

5-Oxo-eicosatetraenoic acid (5-oxoETE) stimulated human neutrophil (PMN) and eosinophil chemotaxis, PMN hexose uptake, and PMN membrane GTP/GDP exchange. Pertussis toxin (PT), a blocker of heterotrimeric G proteins (GP), completely inhibited these responses, but proved far less effective on the same responses when elicited by leukotriene B4, C5a, FMLP, platelet-activating factor, IL-8, or RANTES chemotactic factors. 5-OxoETE also specifically bound to the membrane preparations that conducted GTP/GDP exchange. This binding was down-regulated by GTPgammaS, but not ADPgammaS, and displaced by 5-oxoETE analogues, but not by leukotriene B4, lipoxin A4, or lipoxin B4. Finally, PMN expressed PT-sensitive GP alphaiota2 and PT-resistant GP alphaq/11- and alpha13-chains; eosinophils expressed only alphai2 and alphaq/11. We conclude that 5-oxoETE activates granulocytes through a unique receptor that couples preferentially to PT-sensitive GP. The strict dependency of this putative receptor on PT-sensitive GP may underlie the limited actions of 5-oxoETE, compared with other CF, and help clarify the complex relations between receptors, GP, cell signals, and cell responses.

Arachidonic Acids↗
PubMed2000

The carcinoembryonic antigen (CEA) family (CD66) expressed in melanocytic naevi is not expressed in blue naevuscell naevi in dendritic type.

BACKGROUND: Although sporadic reports have regarded the expression of the carcinoembryonic antigen (CEA) family in melanoma, there has been no information about the expression in precursor lesions of melanoma such as melanocytic naevi and blue naevi. METHODS: The expression was immunohistochemically studied in frozen biopsy specimens of 45 acquired and 16 congenital melanocytic naevi and 20 blue naevi, using a panel of monoclonal and polyclonal antibodies that recognize different epitopes of CEA and related molecules. RESULTS: Members of the CEA glycoprotein family were strongly expressed in all of the subtypes of melanocytic naevus. A reduced expression of the CEA glycoproteins with increased dermal depth or acquisition of a spindled morphology of naevus cells was apparent. The expression was not seen in the present blue naevi and normal epidermal melanocytes. CONCLUSIONS: Although the significance of the expression was not clarified, this report has clearly demonstrated that the CEA family is strongly expressed in melanocytic naevi and immunoreactivity is divergent between melanocytic naevi and blue naevi and between dermal naevus cell types, suggesting that the expression may be altered with architectural changes in the melanocyte-lineage cells.

Adolescent↗
PubMed2000

Nail bed keratinocytes express an antigen of the carcinoembryonic antigen family.

Using a panel of monoclonal and polyclonal antibodies raised against human carcinoembryonic antigen (CEA) and CEA-related molecules, we detected strong expression of an antigen, with immunoreactivity consistent with non-specific cross-reacting antigen (NCA) (CD66c), in all of 26 normal human nail specimens obtained from various fingers and toes. In longitudinal sections, strong and constant expression of the NCA-like antigen was seen on keratinocytes distributed in the upper epithelial cell layers of the nail bed, while in transverse sections the expression was limited to the major central portions of the nail bed, but only where longitudinal epidermal ridges were observed. In the hyponychium and the ventral aspect of the proximal nail fold, the expression was weak or lacking. No expression was seen in the nail matrix, the nail plate, or the dorsal aspect of the proximal nail fold. The same results were obtained for all of the 26 nails studied. This report is the first to demonstrate that an antigen of the CEA family, with NCA-like immunoreactivity, is expressed in a specific subpopulation of keratinocytes in the nail bed. The specific expression pattern suggests that the antigen may play a part in adhesion of the nail plate to the nail bed.

Aged↗
PubMed2000

Effects of macrophage colony-stimulating factor (M-CSF) on anti-fungal activity of mononuclear phagocytes against Trichosporon asahii.

Trichosporon asahii is an emerging opportunistic pathogen in immunocompromised patients. Little is known about the mechanisms of host defence against T. asahii. We investigated the fungicidal activity of human peripheral blood monocytes and murine peritoneal macrophages against T. asahii isolates, and the effects of M-CSF on the anti-fungal activity of mononuclear phagocytes. We also established a neutropenic mouse model of disseminated trichosporonosis with T. asahii. M-CSF enhanced the phagocytic fungicidal activity of mononuclear cells, and infected mice treated with human M-CSF at 10 x 106 U/kg showed a significant improvement in survival rate, with fewer fungal colony counts in the lung compared with control mice. Mice treated with human M-CSF showed higher concentrations of tumour necrosis factor-alpha (TNF-alpha) in the lung and plasma compared with control mice. The survival rate was significantly reduced in mice treated with anti-mouse TNF-alpha. Our results showed that M-CSF enhanced the fungicidal activity of mononuclear phagocytes partly by production of TNF-alpha, and suggest that the administration of M-CSF to patients with disseminated trichosporonosis may be a useful adjunct to conventional anti-microbial therapy and prophylaxis.

Animals↗
PubMed2000

Intrapulmonary concentrations of inflammatory cytokines in a mouse model of chronic respiratory infection caused by Pseudomonas aeruginosa.

We investigated the role of inflammatory cytokines in a mouse model of chronic Pseudomonas aeruginosa infection mimicking diffuse panbronchiolitis (DPB), and determined the effects of clarithromycin therapy on the production of these cytokines. The concentrations of IL-1beta, IL-2, IL-4, IL-5, interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) were measured serially in the lungs of mice with experimentally induced chronic respiratory P. aeruginosa infection until 60 days after inoculation. The concentrations of these cytokines during the course of the disease were significantly higher than baseline (before inoculation, P<0.01 for all cytokines). Clarithromycin significantly inhibited the production of IL-1beta and TNF-alpha in the lung (P<0.01). The same treatment also reduced the levels of other cytokines, albeit insignificantly. Treatment with anti-TNF-alpha antibody significantly reduced the number of pulmonary lymphocytes and concentration of IL-1beta in the lung (P<0.01), but did not change the number of viable bacteria. Our findings resemble those detected in bronchoalveolar lavage fluid of patients with DPB and indicate that inflammatory cytokines play an important role in chronic P. aeruginosa lung infection. Our results also show that macrolides modulated the production of these cytokines, ultimately reducing lymphocyte accumulation in the lung. Our data suggest that anti-TNF-alpha antibody might be a useful new strategy for the treatment of chronic respiratory P. aeruginosa infection.

Animals↗
PubMed2000

Combination therapy for chronic Pseudomonas aeruginosa respiratory infection associated with biofilm formation.

There had been no reports of investigations into biofilms in chronic respiratory infection in vivo. Recently, we established a new murine model of chronic respiratory infection with Pseudomonas aeruginosa. In the present study, we examined the bacteriological effect of combined clarithromycin and levofloxacin against chronic respiratory infection with P. aeruginosa. Scanning electron micrograph of the surface of the catheter intubated in mouse bronchus for 7 days demonstrated in vivo formation of a biofilm containing blood cells, complex fibrous structures and bacteria. Treatment with either clarithromycin alone or levofloxacin alone had no statistical effect on the number of viable bacteria in lung. The combined use of both drugs resulted in a significant decrease in the number of viable bacteria. The present experiment demonstrates that the newly established murine model was useful to investigate the treatment of biofilm-associated chronic respiratory infection with P. aeruginosa, and combination therapy with clarithromycin and levofloxacin was effective in biofilm-associated chronic respiratory infection.

Animals↗
PubMed2000

Adherence protects the binding sites of Helicobacter pylori urease from acid-induced damage.

Colonization by Helicobacter pylori partly depends on acid-dependent adherence by urease to gastric mucin. To further verify the relevance of urease adherence to colonization, the influence of acidity on the binding sites of H. pylori urease was investigated. When enzyme-based in vitro ligand capture assays were used, the effect of acidity on the binding site of H. pylori urease was determined against a backdrop medium consisting of acidic buffers simulating the luminal side of gastric mucus. A high degree of stability was exhibited by adherent urease, suggesting a pivotal role by the denatured enzyme in the persistence of the bacterium within the acidified compartment of gastric mucus.

Bacterial Adhesion↗
PubMed2000

Molecular identification of a human carcinoma-associated glycoprotein antigen recognized by mouse monoclonal antibody FU-MK-1.

Mouse monoclonal antibody FU-MK-1, raised against a human gastric adenocarcinoma, recognizes an antigen (termed MK-1 antigen) present on the majority of carcinomas. The present study aimed to identify the MK-1 molecule and to establish its relationship to other carcinoma antigens. Immunoprecipitation studies of human tumor cell lines revealed that FU-MK-1 recognizes a monomeric membrane glycoprotein with two forms, 40 kDa (major form) and 42 kDa (minor form), and with a molecular mass of 35 kDa following treatment with the N-glycosylation inhibitor tunicamycin. The partial amino acid sequence of a main fragment of the MK-1 molecule obtained by spontaneous cleavage under hypotonic conditions was examined, and the 17 contiguous NH2-terminal amino acids were found to be identical with residues 81-97 of the 314-residue GA733-2 protein [Szala et al.; Proc. Natl. Acad. Sci. USA, 87, 3542-3546 (1990)]. Hence, the GA733-2 cDNA was cloned and the specificity of FU-MK-1 was confirmed using four recombinant forms of the GA733-2 antigen expressed in COS-1 cells. Immunoprecipitation with FU-MK-1 of the cell lysate transfected with the full-length GA733-2 cDNA revealed two bands corresponding to those obtained from the tumor cell lines. FU-MK-1 also precipitated three other recombinant proteins consisting of amino acids 1-265, 1-201, and 1-139 of the GA733-2 protein, respectively. Furthermore, immunoblotting analysis indicated that FU-MK-1 binds to a small fragment (6 kDa) generated from a tumor cell line under hypotonic conditions, suggesting that the FU-MK-1 epitope exists on the distal 6-kDa peptide of the extracellular domain of the GA733-2 molecule. We thus conclude that the MK-1 antigen is the GA733-2 antigen, which is currently being used as a target in clinical trials with monoclonal antibodies.

Amino Acid Sequence↗
PubMed2000

Avidin chase can reduce myelotoxicity associated with radioimmunotherapy of experimental liver micrometastases in mice.

Myelotoxicity is the main factor which decides the maximum tolerated dose (MTD) in radioimmunotherapy (RIT). Since bone marrow is mostly irradiated from blood radioactivity, enhancing the clearance of unbound circulating radiolabeled antibody is important to reduce myelotoxicity and to increase the MTD. We applied the avidin chase method, which was devised to obtain high tumor-to-background ratios in tumor-targeting, to RIT of experimental liver micrometastases and evaluated its influence on the side effects and therapeutic outcome. Seven days after intrasplenic injection of human colon cancer LS174T cells, nude mice were intravenously injected with biotinylated (131)I-labeled anti-CEA monoclonal antibody (MAb) (24 - 38 microg, 11.1 MBq). Mice of the chase group then received an intravenous injection of avidin twice (24 and 30 h, 72 - 115 microg each). Biodistribution, side effects (white blood cell counts and body weight change), and short- and long-term therapeutic effects were determined. Avidin chase markedly accelerated the clearance of radiolabeled MAb from the blood (P < 0.0001) and normal tissues, resulting in milder leukocytopenia and body weight loss, both of which recovered earlier than in the non-chase group (P < 0.01). The tumor uptake of radiolabeled MAb was also decreased by avidin chase, but the metastases-to-background ratios were increased. Avidin chase gave the therapeutic gain ratio of 1.89. Treated groups with and without avidin chase showed significant therapeutic effects compared to the non-treated group. There was no significant difference in the therapeutic effects between the two treated groups. Avidin chase effectively reduced the side effects of RIT and should increase the MTD.

Animals↗
PubMed2000

A new spontaneously diabetic non-obese Torii rat strain with severe ocular complications.

A new spontaneously diabetic strain of the Sprague-Dawley rat was established in 1997 and named the SDT (Spontaneously Diabetic Torii) rat. In this research, we investigated the characteristics of the disease condition in the SDT rats. The time of onset of glucosuria was different between male and female SDT rats; glucosuria appeared at approximately 20 weeks of age in male rats and at approximately 45 weeks of age in female rats. A cumulative incidence of diabetes of 100% was noted by 40 weeks of age in male rats, while it was only 33.3% even by 65 weeks of age in female rats. The survival rate up to 65 weeks of age was 92.9% in male rats and 97.4% in female rats. Glucose intolerance was observed in male rats from 16 weeks of age. The clinical characteristics of the male SDT rats were (1) hyperglycemia and hypoinsulinemia (from 25 weeks of age); (2) long-term survival without insulin treatment; (3) hypertriglyceridemia (by 35 weeks of age); however, no obesity was noted in any of the male rats. The histopathological characteristics of the male rats with diabetes mellitus (DM) were (1) fibrosis of the pancreatic islets (by 25 weeks of age); (2) cataract (by 40 weeks of age); (3) tractional retinal detachment with fibrous proliferation (by 70 weeks of age) and (4) massive hemorrhaging in the anterior chamber (by 77 weeks of age). These clinical and histopathological characteristics of the disease in SDT rats resemble those of human Type 2 diabetes with insulin hyposecretion. In conclusion, SDT rat is considered to be a potentially useful model for studies of diabetic retinopathy encountered in humans.

Animals↗
PubMed2000

Production and accumulation of thrombospondin-1 in human retinal pigment epithelial cells.

PURPOSE: To investigate the production and release of thrombospondin-1 (TSP-1), a natural inhibitor of angiogenesis, by human retinal pigment epithelial (RPE) cells to clarify the possible role of TSP-1 in maintaining intraocular angiogenesis. METHODS: Human RPE cells were isolated from a human cadaveric eye and cultured in medium with 5% newborn calf serum. TSP-1 messages in the purified RNA of RPE cells were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). Intracellular TSP-1 peptides were detected by cytofluorographic analysis. TSP-1 peptides in the culture medium on RPE cells were measured by sandwich enzyme-linked immunosorbent assay (ELISA). TSP-1 specific immunofluorescent staining was tested in RPE cells cultured on glass slides and in a human retinal tissue specimen. RESULTS: mRNA specific for TSP-1 was found in RT-PCR products from RPE cells, and it showed a time-dependent increase from the beginning of the culture. Intracellular staining for TSP-1 was identified by flow cytometry. The sandwich ELISA identified a time-dependent increase of TSP-1 peptides in the culture medium of RPE cells. Immunostaining for TSP-1 was observed in the cytoplasm of RPE cells cultured on glass slides. Positive immunostaining of TSP-1 was observed in the cytoplasm of the RPE layer in the human retinal tissue specimen. CONCLUSIONS: RPE cells can produce and release TSP-1 in vitro, and TSP-1 accumulates in the cytoplasm of RPE cells in vivo as well as in vitro. The production of TSP-1 by RPE cells is influenced by the state of proliferation and/or cell density. TSP-1 appears to be an important control factor in retinal and choroidal neovascularization.

Antibodies, Monoclonal↗
PubMed2000

CaNa2EDTA for improvement of radioimmunodetection and radioimmunotherapy with 111In and 90Y-DTPA-anti-CEA MAbs in nude mice bearing human colorectal cancer.

UNLABELLED: 111In and 90Y, dissociated from 111In-labeled-monoclonal antibody (MAb) and 90Y-labeled MAb, may cause deterioration of the image quality in radioimmunodetection (RID) and undesirable irradiation of nontargeted tissue in radioimmunotherapy (RIT), respectively. The aim of this study was to investigate any improvement in RID and RIT with 111In-MAb and 90Y-MAb by pre- and postadministration of calcium disodium ethylenetriaminetetraacetic acid (CaNa2EDTA). METHODS: Murine MAb F33-104 against carcinoembryonic antigen (CEA) was labeled with 111In or 90Y by the diethylenetriamine pentaacetic (DTPA)-anhydride method. The influence of CaNa2EDTA on loss of radioactivity from 111In-MAb or 90Y-MAb in serum was investigated in vitro. The effects of CaNa2EDTA, administered before and after 111In-MAb or 90Y-MAb, on the biodistribution of radioactive isotopes in nude mice bearing human colon adenocarcinoma LS 180 tumor expressing CEA, or human pulmonary carcinoma PC 9 tumor expressing no CEA, were then examined. As a control, 0.9% NaCl was used in both the in vitro and in vivo studies. RESULTS: CaNa2EDTA did not cause any decrease in levels of radioactivity of radiolabeled MAbs. Pre- and post-treatment with CaNa2EDTA reduced radioctivity in both specific and nonspecific tumors at 72 h after 111In-MAb injection resulting in an increase of the specific tumor-to-nonspecific tumor radioactivity ratio. The levels of hepatic and renal radioactivity were also subsequently decreased by CaNa2EDTA. On the other hand, CaNa2EDTA pre- and post-treatment reduced levels of bony, hepatic, and renal radioactivity at 24, 72, and 72 h, respectively, after 90Y-MAb injection, although it had no effect on tumor radioactivity. CONCLUSION: Pre- and post-treatment with CaNa2EDTA would be of great use in humans who undergo RID or RIT with 111In-MAb and 90Y-MAb accompanied by disassociation of the labeled radionuclides.

Animals↗
PubMed2000

Fatal hepatic failure caused by chemotherapy-induced reactivation of hepatitis B virus in a patient with hematologic malignancy.

A patient with hematologic malignancy and hepatitis B virus (HBV) infection received chemotherapy containing a glucocorticoid. The patient developed severe hepatitis after chemotherapy and, despite achieving complete remission of the malignancy, died of hepatic failure. We carried out a retrospective study of changes in the serological markers of HBV in this patient. Both serum hepatitis B surface antigen (HBsAg) and hepatitis B surface antibody (HBsAb) were negative on admission. During the course of chemotherapy, HBsAg gradually became positive, but no liver dysfunction was apparent until after completion of the chemotherapy. The patient showed no initial evidence of being a latent HBV carrier. Therefore, we believe that screening for HBsAg is insufficient for detecting latent HBV carriers, and that investigation for hepatitis B core antibody (HBcAb) is essential.

Aged↗