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Biomedical subjects

M Kuroki

Publications and source records attributed to M Kuroki.

At least 91 records · Page 5Linked to original sources
PubMed1997

Field evaluation of chicken egg yolk immunoglobulins specific for bovine rotavirus in neonatal calves.

The oral efficacy of chicken egg yolk immunoglobulins (yIg) specific for bovine rotavirus (BRV) serotypes G6 and G10 in protecting neonatal calves was examined in a herd of cattle under field conditions. In one of the three trials, yIg-treated calves tested under high relative humidity (RH) showed a significantly increased mean body weight (P < 0.05) and a decrease in number of calves shedding high titer of BRV (G6) in stool compared to control calves (P < 0.01), suggesting that our yIg product was effective in a field condition with an epidemic outbreak of BRV diarrhea.

Animals↗
PubMed1997

Passive protection of neonatal calves against bovine coronavirus-induced diarrhea by administration of egg yolk or colostrum antibody powder.

The protective effect of egg yolk and colostrum powders prepared from hens and cows vaccinated with inactivated bovine coronavirus (BCV) antigen was evaluated in a challenge model with a virulent BCV strain. Twenty three calves from BCV-free herds were randomly divided into control and several treatment groups. All calves were orally challenged with 1 x 10(9) TCID50 of the virulent Kakegawa strain of BCV at 24 to 36 h after birth. Calves in treatment groups received either egg yolk powder or cow colostrum containing BCV specific antibodies. Daily treatment with these antibody preparations started 6 h until 7 days post-challenge. Control calves which received no antibody had severe diarrhea and all died within 6 days after infection. In contrast, calves fed milk containing egg yolk or colostrum with neutralization titers of 1:2560 or 1:10,240 respectively all survived and had positive weight gain unlike the other treatment groups. These results indicate that the orally administered egg yolk and colostrum powders protected against BCV-induced diarrhea in neonatal calves and that the egg yolk used provided a higher degree of protection compared to colostrum powder on a titer basis. Treatment with whole egg yolk from immunized hens therefore provides a more efficacious alternative to the existing methods of specific passive protection against BCV.

Animals↗
PubMed1997

Binding of spermatozoa to the perivitelline layer in the presence of a protease inhibitor.

The extracellular investment of oocytes in a number of species contains species-specific receptors to which spermatozoa bind as a prelude to fertilization; however, little is known about the nature and distribution of sperm receptors in avian oocytes. In order to elucidate the early step of fertilization in birds, we observed the binding of spermatozoa to the perivitelline layer (PL) of quail ova. When the PL obtained from the largest follicles were incubated in vitro with spermatozoa, perforations were observed. The presence of trypsin inhibitors during incubation inhibited the sperm-induced perforations of the PL and binding of spermatozoa to the PL could be observed. The number of spermatozoa bound to the PL increased in the ovum from more mature follicles, and concentrated binding of spermatozoa to the PL overlying the germinal disc region was observed in the largest follicle. The number of spermatozoa bound to the PL overlying the germinal disc region decreased in the oviposited eggs. These results demonstrate that sperm receptors exist in the PL over the germinal disc in the mature follicle.

Acrosome↗
PubMed1997

A monoclonal antibody modulates neutrophil adherence while enhancing cell motility.

A monoclonal antibody (MoAb) to human neutrophils, designated 3H9, was established by screening for the inhibition of neutrophil adherence to plastic plates containing a medium supplemented with fetal calf serum (FCS medium). The antigen recognized by 3H9 was shown to be present on human leukocytes and found at the highest levels on granulocytes. On Western blotting, 3H9 reacted with a molecule having a molecular weight of 80 kDa. When this MoAb was added at the same time as a neutrophil stimulant (fMLP), the inhibition of neutrophil adherence to plastic plates in the presence of FCS medium was observed after 60 min incubation. Furthermore, this MoAb enhanced not only fMLP-induced chemotaxis but random migration of neutrophils as well. The mechanisms of these phenomena are discussed.

Animals↗
PubMed1997

[A case of pulmonary zygomycosis caused by Cunninghamella bertholletiae].

Cunninghamella bertholletiae, a rare causative agent of human deep seated mycosis, has been reported with increased frequency in the Western countries, in recent years. We experienced a case of Cunninghamella bertholletiae pulmonary infection in a 63-year-old male with pulmonary fibrosis and mild diabetes mellitus. In spite of intensive anti-fungal chemotherapy following clinical diagnosis, he died of exacerbation of the underlying diseases. Postmortem examination showed Cunninghamella infection in the cavity of the lung and massive pulmonary fibrosis. There was no fungal invasion outside the cavity. This is the third report of Cunninghamella human infection in Japan.

Aged↗
PubMed1997

Effect of oral egg antibody in experimental F18+ Escherichia coli infection in weaned pigs.

The protection conferred by egg antibody specific for F18-fimbriae against infection with F18+ Escherichia coli was studied in controlled passive immunization trials involving weaned pigs. Parameters of protection consisted of body weight gain, frequency and severity of diarrhea and recovery of the challenge strain of F18+ E. coli. Weaned pigs at four weeks of age were challenge exposed once daily for three days by oral inoculation with 10(11) cfu of virulent F18+ E. coli followed by daily administration of antibody supplemented feed for 9 days starting from the first challenge day 0. Results showed a dose-dependent response to antibody treatment. The group of pigs given 1:50 titer of antibody in feed had less frequency of diarrhea (P < 0.01-0.05), higher rate of gain (P < 0.01) and lower isolation rate of challenge strain in rectal and intestinal swabs (P < 0.01) compared to non-treated control. In the same manner, the anti-F18 antibody significantly reduced adherence of F18+ E. coli to pig intestinal epithelial cells in vitro (P < 0.01). Results suggest that egg antibodies specific for the F18 fimbriae is a suitable immunotherapeutic agent for pigs infected with F18+ E. coli and that pigs can be protected from overt clinical disease and the subsequent reduced performance arising from infection with this pathogen.

Administration, Oral↗
PubMed1997

Regulation of vascular endothelial growth factor expression by insulin-like growth factor I.

Insulin-like growth factor I (IGF-I) and vascular endothelial growth factor (VEGF) levels are correlated with retinal ischemia-associated intraocular neovascularization in humans. Since VEGF is required for iris and retinal neovascularization in animal models of retinal ischemia, we tested whether IGF-I could act as an indirect angiogenic factor by increasing VEGF gene expression. IGF-I increased retinal pigment epithelial (RPE) cell VEGF mRNA in a concentration-dependent manner with an EC50 of 7 nmol/1 (53.6 ng/ml). RPE and bovine smooth muscle cells exposed to 50 nmol/l (383 ng/m1) IGF-I achieved peak VEGF mRNA expression within 2 h. IGF-I-treated RPE cells increased VEGF protein levels in conditioned media and stimulated capillary endothelial cell proliferation. Blockade of the IGF-I receptor with a neutralizing antibody abrogated the VEGF increases in RPE cells. Further, hypoxia-mediated and IGF-I-mediated increases in VEGF mRNA and protein levels were additive in RPE cells, and the hypoxia-induced VEGF increases were independent of endogenous IGF-I. VEGF promoter activity was enhanced by IGF-I in RPE cells, but VEGF transcript half-life was unaltered. In summary, the supplementation of RPE and smooth muscle cell cultures with IGF-I at 5-100 nmol/l increased VEGF mRNA and secreted protein levels. The VEGF increases in RPE cells occurred primarily through enhanced transcription of the VEGF gene and via the IGF-I receptor. Elevated IGF-I levels may promote neovascularization through increased retinal VEGF gene expression.

Animals↗
PubMed1996

Reactive oxygen intermediates increase vascular endothelial growth factor expression in vitro and in vivo.

Elevated vascular endothelial growth factor (VEGF) levels are required for ocular and tumor angiogenesis in animal models. Ischemic hypoxia is strongly correlated with increased VEGF expression in these systems and is considered a physiologically relevant stimulus. Because ischemic hypoxia is often followed by reperfusion and reactive oxygen intermediate (ROI) generation, we examined the potential role of ROI in the control of VEGF gene expression. Human retinal pigment epithelial cells exposed to superoxide or hydrogen peroxide rapidly increased VEGF mRNA levels. Superoxide-associated mRNA increases were dose dependent, blocked by antioxidants, and associated with elevated VEGF protein levels in conditioned media. Increases in VEGF mRNA levels were also observed in cultured human melanoma and rat glioblastoma cells with superoxide or hydrogen peroxide. Cycloheximide prevented the ROI-associated increases in VEGF mRNA. Transcriptional inhibition with actinomycin D revealed an inducible increase in VEGF mRNA half-life, but nuclear run-on experiments showed no increase in VEGF transcriptional rate. Reoxygenation of human retinal pigment epithelial cells in vitro and ocular reperfusion in vivo increased retinal VEGF mRNA levels. Antioxidants prevented the reperfusion-associated VEGF mRNA increases in retina. We conclude that ROIs increase VEGF gene expression in vitro and during the reperfusion of ischemic retina in vivo. The ROI-associated increases are mediated largely through increases in VEGF mRNA stability.

Animals↗
PubMed1996

Up-regulation of vascular endothelial growth factor production by iron chelators.

Agents that modulate cellular iron availability have been studied for their antitumor activity. Based on encouraging in vitro studies, the iron chelator deferoxamine (DFO) has been used in clinical studies to treat cancer patients. The observation that DFO induced macular edema in several cancer patients led to the present investigation of vascular endothelial growth factor (VEGF) as a possible mediator of the encountered side effects. Both normal and malignant cell lines were incubated with DFO and a variety of other iron chelators. DFO, at concentrations achievable in humans, induced a 3-5-fold increase in VEGF mRNA expression in all cell lines studied. This increased VEGF mRNA expression was dose and time dependent. A panel of structurally different iron chelators induced an even more potent increase in VEGF mRNA expression. The DFO-induced increase in VEGF mRNA expression translated into 6- and 4-fold increases in VEGF protein secretion in conditioned media of retinal pigment epithelial and C6 glioblastoma cells, respectively. These findings suggest that VEGF may act as a mediator of the side effects induced by iron chelation therapy. In addition, because VEGF is an important regulator of angiogenesis, iron chelators should be given with caution to cancer patients.

Animals↗
PubMed1996

5-Oxo-eicosanoids and hematopoietic cytokines cooperate in stimulating neutrophil function and the mitogen-activated protein kinase pathway.

The newly defined eicosatetraenoates (ETEs), 5-oxoETE and 5-oxo-15(OH)-ETE, share structural motifs, synthetic origins, and bioactions with leukotriene B4 (LTB4). All three eicosanoids stimulate Ca2+ transients and chemotaxis in human neutrophils (PMN). However, unlike LTB4, 5-oxoETE and 5-oxo-15(OH)-ETE alone cause little degranulation and no superoxide anion production. However, we show herein that, in PMN pretreated with granulocyte-macrophage or granulocyte colony-stimulating factor (GM-CSF or G-CSF), the oxoETEs become potent activators of the last responses. The oxoETEs also induce translocation of secretory vesicles from the cytosol to the plasmalemma, an effect not requiring cytokine priming. To study the mechanism of PMN activation in response to the eicosanoids, we examined the activation of mitogen-activated protein kinase (MAPK) and cytosolic phospholipase A2 (cPLA2). PMN expressed three proteins (40, 42, and 44 kDa) that reacted with anti-MAPK antibodies. The oxoETEs, LTB4, GM-CSF, and G-CSF all stimulated PMN to activate the MAPKs and cPLA2, as defined by shifts in these proteins' electrophoretic mobility and tyrosine phosphorylation of the MAPKs. However, the speed and duration of the MAPK response varied markedly depending on the stimulus. 5-OxoETE caused a very rapid and transient activation of MAPK. In contrast, the response to the cytokines was rather slow and persistent. PMN pretreated with GM-CSF demonstrated a dramatic increase in the extent of MAPK tyrosine phosphorylation and electrophoretic mobility shift in response to 5-oxoETE. Similarly, 5-oxoETE induced PMN to release some preincorporated [14C]arachidonic acid, while GM-CSF greatly enhanced the extent of this release. Thus, the synergism exhibited by these agents is prominent at the level of MAPK stimulation and phospholipid deacylation. Pertussis toxin, but not Ca2+ depletion, inhibited MAPK responses to 5-oxoETE and LTB4, indicating that responses to both agents are coupled through G proteins but not dependent upon Ca2+ transients. 15-OxoETE and 15(OH)-ETE were inactive while 5-oxo-15(OH)-ETE and 5(OH)-ETE had 3- and 10-fold less potency than 5-oxoETE, indicating a rather strict structural specificity for the 5-keto group. LY 255283, a LTB4 antagonist, blocked the responses to LTB4 but not to 5-oxoETE. Therefore, the oxoETEs do not appear to operate through the LTB4 receptor. In summary, the oxoETEs are potent activators of PMN that share some but not all activities with LTB4. The response to the oxoETEs is greatly enhanced by pretreatment with cytokines, indicating that combinations of these mediators may be very important in the pathogenesis of inflammation.

Arachidonic Acid↗
PubMed1996

5-Oxo-eicosatetraenoate is a broadly active, eosinophil-selective stimulus for human granulocytes.

5-Oxo-eicosatetraenoate (5-oxoETE) is gaining recognition as a chemotactic factor for eosinophilic (Eo) as well as neutrophilic (Neu) polymorphonuclear leukocytes. We found that the eicosanoid was far stronger than C5a, platelet-activating factor (PAF), leukotriene B4 (LTB4), or FMLP in stimulating Eo chemotaxis. Moreover, it had weak intrinsic degranulating effects on otherwise unstimulated Eo, produced prominent degranulation responses in Eo primed by granulocyte-macrophage CSF, and enhanced the Eo-degranulating potencies of PAF, C5a, LTB4, and FMLP by up to 10,000-fold. Low picomolar levels of 5-oxoETE also induced Eo to activate mitogen-activated protein kinases (MAPKs), as defined by shifts in the electrophoretic mobility and tyrosine phosphorylation of two immunodetectable proteins, p44 and p42. 5-OxoETE was > or = 100-fold weaker or unable to stimulate any of these responses in Neu. Finally, 5-oxo-15-hydroxy-ETE and 5-hydroxy-ETE activated both cell types, but were weaker than 5-oxoETE and had Eo/Neu potency ratios approaching unity. 5-OxoETE, thus, is uniquely potent and selective in promoting Eo not only to migrate, but also to release granule enzymes and activate MAPKs. By triggering MAPK activation, the eicosanoid may also influence the production of anaphylactoid lipids (e.g., PAF), arachidonic acid metabolites, and cytokines. 5-OxoETE therefore possesses a biologic profile well suited for mediating Eo-dominated allergic reactions in vivo.

Arachidonic Acids↗
PubMed1996

Analysis of heterophilic cell adhesion mediated by CD66b and CD66c using their soluble recombinant proteins.

The heterophilic cell adhesion mediated by CD66b (carcinoembryonic antigen (CEA) gene family member 6, CGM6) and CD66c (nonspecific cross-reacting antigen, NCA), both CEA family members expressed on neutrophils, was investigated using their soluble recombinant proteins prepared in silkworm larvae. The recombinant CD66b and CD66c immobilized on plastic bound CHO transfectants expressing CD66c and CD66b, respectively. Their deglycosylated forms retained the adhesion activity, suggesting that their carbohydrate portions are not prerequisite for the binding. This cell adhesion appeared to be mediated via interaction between the N domains of CD66b and CD66c, because CD66 antibodies recognizing their N domains inhibited the binding. Neutrophils, when activated, adhered to the immobilized CD66b and CD66c. In addition, the binding of primed neutrophils to the antigens induced superoxide anion release. The cell adhesion mediated by CD66b and CD66c may play a role in interaction between neutrophils or between neutrophils and epithelial cells expressing CD66c in vivo.

Animals↗
PubMed1996

The mouse gene for vascular endothelial growth factor. Genomic structure, definition of the transcriptional unit, and characterization of transcriptional and post-transcriptional regulatory sequences.

We describe the genomic organization and functional characterization of the mouse gene encoding vascular endothelial growth factor (VEGF), a polypeptide implicated in embryonic vascular development and postnatal angiogenesis. The coding region for mouse VEGF is interrupted by seven introns and encompasses approximately 14 kilobases. Organization of exons suggests that, similar to the human VEGF gene, alternative splicing generates the 120-, 164-, and 188-amino acid isoforms, but does not predict a fourth VEGF isoform corresponding to human VEGF206. Approximately 1. 2 kilobases of 5'-flanking region have been sequenced, and primer extension analysis identified a single major transcription initiation site, notably lacking TATA or CCAT consensus sequences. The 5'-flanking region is sufficient to promote a 7-fold induction of basal transcription. The genomic region encoding the 3'-untranslated region was determined by Northern and nuclease mapping analysis. Investigation of mRNA sequences responsible for the rapid turnover of VEGF mRNA (mRNA half-life, <1 h) (Shima, D. T. , Deutsch, U., and D'Amore, P. A. (1995) FEBS Lett. 370, 203-208) revealed that the 3'-untranslated region was sufficient to trigger the rapid turnover of a normally long-lived reporter mRNA in vitro. These data and reagents will allow the molecular and genetic analysis of mechanisms that control the developmental and pathological expression of VEGF.

Alternative Splicing↗
PubMed1996

Preparation and characterization of two human carcinoembryonic antigen family proteins of neutrophils, CD66b and c, in silkworm larvae.

As a step to investigate the cell adhesion mechanism and physiological roles of two CD66 antigens in human neutrophils, carcinoembryonic antigen gene family member 6 (CGM6, CD66b) and nonspecific cross-reacting antigen (NCA, CD66c), we prepared their soluble recombinant forms in silkworm larvae. Each cDNA fragment for CGM6 and NCA was ligated into the transfer vector pBK283 after modification to encode the protein lacking the membrane anchor. The resultant vectors were introduced to the Bombyx mori nuclear polyhedrosis virus, with which silkworm larvae were infected. Recombinant proteins secreted into the hemolymph of larvae at concentrations up to 1.3 mg/ml were purified by cation exchange followed by gel filtration or antibody affinity chromatography. The smaller apparent masses of the antigens compared with those of the native antigens appeared to be primarily due to incomplete glycosylation. Both recombinant antigens are quite similar to the corresponding native antigens in terms of the antigenic reactivity against a panel of CD66 monoclonal antibodies. In addition, the recombinant CGM6 and NCA exhibited cell binding activity against CHO cells expressing NCA and CGM6, respectively. Thus the two biologically active recombinant CD66 antigens prepared in large quantities in silkworm larvae should be useful for their functional studies, and our present system will be available for the production and purification of other carcinoembryonic antigen family members, whose biological functions are also unknown.

Animals↗
PubMed1996

Radioimmunoscintigraphy using technetium-99m-labeled parental mouse and mouse-human chimeric antibodies to carcinoembryonic antigen in athymic nude mice bearing tumor.

Biodistribution and imaging characteristics of Tc-99m-labeled parental mouse and mouse-human chimeric antibodies to carcinoembryonic antigen (CEA), designated F11-39 and ChF11-39, respectively, were evaluated in athymic nude mice bearing the human CEA-producing gastric carcinoma (MKN-45) xenografts. Group F monoclonal antibodies such as F11-39 and ChF11-39 have been found to recognize the protein epitopes present on the domain B3 of the CEA molecule and to discriminate CEA in tumor tissues from the CEA-related antigens. The Tc-99m labeling was performed by immediately mixing a reduced antibody by 2-mercaptoethanol with Tc-99m pertechnetate in the presence of stannous chloride. The labeling yields of the two antibodies were greater than 95% when estimated using gel chromatography. Although these Tc-99m-labeled antibodies were stable in neutral saline solution, Tc-99m from both labeled antibodies was associated with cysteine solution. Technetium-99m ChF11-39 was more susceptible to transchelation than was Tc-99m F11-39. The immunoreactivity of each Tc-99m-labeled antibody was confirmed using MKN-45 cell-binding assay. Biodistribution studies in tumor-bearing mice were performed at 1 h, 5 h, and 20 h after being given IV injections of 3.7 MBq of either Tc-99m F11-39 or Tc-99m ChF11-39. All tumor-to-organ uptake ratios increased with time for both Tc-99m-labeled antibodies. Imaging results also showed selective and progressive accumulation of both Tc-99m antibodies at the tumor site. Both these Tc-99m-labeled antibodies have proved to be good radiotracers giving satisfactory scintigrams of the CEA-producing tumor.

Animals↗
PubMed1996

Tumor-specific accumulation of 125I-labeled mouse-human chimeric anti-CEA antibody in a xenografted human cancer model demonstrated by whole-body autoradiography and immunostaining.

Whole-body autoradiography (WBAR) was used to study the biodistribution of 125I-labeled mouse-human chimeric antibody (Ch F11-39) to carcinoembryonic antigen (CEA) in athymic nude mice bearing the CEA-producing MKN-45 human gastric carcinoma xenografts. Significantly high uptake of 125I-Ch F11-39 in the tumors obtained by tissue-counting technique was confirmed by WBAR of mice of 12, 24, 48, and 96 h postinjection of 125I-Ch F11-39. When compared with histochemical or immunohistochemical staining results of the tumor tissue sections, imaging profiles of 125I-Ch F11-39 obtained by WBARs were topographically correlated with histopathological findings of tissues and immunohistochemical localization of CEA in the tumor tissues, indicating that the accumulation of 125I-Ch F11-39 at the tumor site is based on its specificity for CEA. These results demonstrate that this chimeric antibody may serve as a potential useful diagnostic and/or therapeutic reagent for human CEA-producing cancers.

Animals↗
PubMed1996

Cloning and sequencing of the VH and V kappa genes of an anti-CD3 monoclonal antibody, and construction of a mouse/human chimeric antibody.

Mouse monoclonal antibodies against CD3 on human T lymphocytes have been used for therapy in organ-transplant patients as a potent immunosuppressive agent or for treatment of cancer as a potent T cell activating agent. However, an inherent problem in their in vivo application is the human anti-mouse antibody response. In this study, we cloned and sequenced the variable region genes of the heavy and light chains (VH and V kappa) of a mouse anti-human CD3 monoclonal antibody (OKT3) using the reverse transcription-polymerase chain reaction method. Then, we constructed a mouse/human chimeric antibody, designated as Ch OKT3, by fusing the OKT3 VH and V kappa genes to the human heavy and light chain constant region genes (C gamma 1 and C kappa) derived from a human plasma cell leukemia line (ARH77), respectively. The chimeric gene constructs were sequentially co-transfected into mouse non-Ig-producing hybridoma cells (Sp2/0) by electroporation. The Ch OKT3 antibody thus prepared bound to human peripheral blood mononuclear cells and competitively inhibited the binding of the parental MAb OKT3 to the blood mononuclear cells, indicating that this chimeric antibody seems to be suitable for in vivo therapeutic approaches.

Amino Acid Sequence↗