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Biomedical subjects

K Toda

Publications and source records attributed to K Toda.

At least 73 records · Page 4Linked to original sources
PubMed1998

Delta-9 fatty acid desaturase gene containing a carboxyl-terminal cytochrome b5 domain from the red alga Cyanidioschyzon merolae.

A delta-9 fatty acid desaturase gene, homologous to animal and fungal acyl-coenzyme A (CoA) desaturases, was isolated from the red alga Cyanidioschyzon merolae using a degenerate PCR strategy. This gene, designated as CmFAD9, has no intron. The encoded delta-9 fatty acid desaturase (CmFad9p) consists of 476 amino acids and has an estimated molecular mass of 55.4 kDa. CmFad9p is a unique delta-9 fatty acid desaturase among plants, in that it is fused with the cytochrome b5 domain at its carboxyl terminus. This is characteristic of yeast acyl-CoA desaturase. Genomic Southern hybridization suggested that the C. merolae genome contains a single gene for delta-9 fatty acid desaturase of the animal and fungal type. Southern hybridization combined with pulsed-field gel electrophoresis revealed that CmFAD9 is probably located on chromosome XI of the 17 C. merolae chromosomes. A 1.6-kb product of this gene was transcribed throughout a light/dark synchronization culture. The discovery of CmFAD9 indicates the existence of a novel type of plant delta-9 fatty acid desaturase that may function in the endoplasmic reticulum, but not in the plastid.

Amino Acid Sequence↗
PubMed1998

Histological evaluation of the effects of intraarterial chemotherapy for advanced breast cancer: a long-term followup study with respect to the survival rate.

To evaluate the effects of intraarterial infusion chemotherapy (IAIC) for advanced breast cancer, we examined the grade of histological responses of preoperative IAIC on tumors at the time of operation and estimated the patients' prognoses for 19 years. IAIC was done preoperatively using timely epochal anticancer drugs on 105 patients with locally advanced (Stage IIIa, IIIb) and metastatic (Stage IV) breast cancer. The survival rate of the Stage IIIb patients who showed a good histological response (Grade IIb< or =) to IAIC was 68.1% for 5 years, and 62.4% for 10 years, respectively. This was in contrast to that of the patients classified as Stage IIIb who showed a poor histological response (Grade IIa> or =) to IAIC. On the other hand, there was no significant difference in the survival rates between the Stage IIIa and IV patients with good and poor histological responses to IAIC. However, the findings showed that a good histological response to IAIC reflected a prolonged survival while the Stage IIIb and IV patients acquired a "down clinical staging" by IAIC. These results strongly suggest that IAIC thus appears to be a useful modality in the multidisciplinary treatment of advanced breast cancer, especially for Stage IIIb patients.

Adult↗
PubMed1998

Antinociceptive effects of neurotropin in a rat model of painful peripheral mononeuropathy.

A non-protein extract isolated from the inflamed skin of rabbits inoculated with vaccinia virus (Neurotropin, NTP), has been clinically used in Japan for the treatment of chronic painful conditions such as low back pain, osteoarthritis, postherpetic neuralgia, subacute myelo-opticoneuropathy, and so on. Recent studies have shown its efficacy on patients with complex regional pain syndrome (CRPS). The chronic constriction injury (CCI) model described by Bennett and Xie has been thought to show similar painful conditions to those seen in CRPS patients. Thus, the antinociceptive effects of NTP were tested in CCI model. In rats with mechanical hyperalgesia 2 weeks after nerve injury, i.p. injection of NTP (100 Neurotropin Unit, NU/kg) produced an analgesic effect that lasted for at least 50 min. An analgesic effect lasting up to 30 min. was observed in rats with heat hyperalgesia 2 weeks after nerve injury. Seven daily i.p. injections (50 NU/kg) of NTP commencing 1 week after surgery produced an early recovery from heat hyperalgesia. Prior studies suggest that NTP produces analgesia by activation of a descending pain inhibitory system. Thus, our findings suggest the possibility that the dysfunction of the descending pain inhibitory system could be related to the hyperalgesia in the nerve injury model, and perhaps also in people who suffer from painful peripheral neuropathies.

Analgesics↗
PubMed1998

The division apparatus of plastids and mitochondria.

Mitochondria and plastids in eukaryotic cells contain distinct genomes and multiply in the cytoplasm by binary division of preexisting organelles. Mitochondrial and plastid nuclei are easily visualized as compartments in the matrix of organelles by high-resolution fluorescence microscopy and by immunoelectron microscopy using anti-DNA antibodies. Plastid and mitochondrial division can be clearly separated into two main events: division of the organelle nuclei, and then division of the rest of the organelles, the process of organellokinesis (mitochondriokinesis and plastidokinesis). The mechanical apparatus that regulates organellokinesis has remained undetermined. In 1986, the plastid-dividing apparatus (PD ring) for plastidokinesis was first identified by us in the primitive red alga Cyanidium caldarium RK-1. The PD ring is located in the cytoplasm outside the organelle envelope at the constricted isthmus of dividing organelles and has subsequently been found in all eukaryotic plants examined. We were also the first to identify the mitochondrion-dividing apparatus (MD ring) for mitochondriokinesis in the unicellular red alga Cyanidioschyzon merolae in 1993. Eukaryotic cell division is therefore controlled by at least three dividing apparata (rings), a contractile ring, an MD ring, and a PD ring, while bacterial division is controlled by a single bacterial contractile FtsZ ring. The aims of this review are to present the fine structure, process of formation, and contraction of the organelle-dividing apparatus, focusing on evolutionary conservation and diversion from the bacterial contractile ring.

Cell Division↗
PubMed1998

Further characterization of a new in vitro angiogenesis model under serum free culture conditions; suppression of endothelial cell differentiation by serum.

We studied the regulation of the extracellular matrix in the recently established murine vascular endothelial cell clones, F-2 or F-2C. F-2 cells constitutively show a cobblestone growth pattern under serum supplemented culture conditions, whereas F-2C cells undergo spontaneous histodifferentiation to form tubular structures in chemically defined media. We reported that the tubulogenesis induced by F-2C might relate to the heavy deposition of a 'basement membrane analog' as a subendothelial matrix (SEM). We further characterized the regulation of extracellular matrix (ECM) metabolism in these cell clones, in terms of gelatinase expression, ECM degradation and the effects of serum. F-2C cells in culture medium containing 1% serum did not undergo tubulogenesis but presented cobblestone growth. Zymography analysis showed that both F-2 and F-2C cells express two gelatinase (72 and 92 kDa). However, F-2 cells mainly expressed the former and faintly the latter, whereas F-2C mainly expressed the latter. Proteolysis studies showed that the spent media conditioned by F-2C cells partially cleaved type IV collagen and completely degraded type V collagen. The cleavage of type V collagen was suppressed by the addition of serum, whereas that of type IV collagen was not. The proteolysis of laminin and fibronectin by the conditioned medium was not observed. Serum-supplemented F-2 or F-2C cultures markedly suppressed SEM deposition. These results indicated that F-2C cells under serum free culture conditions not only present a simple and useful in vitro model with which to study the dynamic processes of proteolysis and ECM metabolism during the sequential phases of angiogenesis, but is also useful for analyzing the serum effects on angiogenesis (AG).

Animals↗
PubMed1998

Induction of apoptosis, p53 and heme oxygenase-1 by cytotoxic prostaglandin delta12-PGJ2 in transformed endothelial cells.

Delta12-prostaglandin (PG)J2, which has been reported to have potent growth inhibitory activity in various tumor cells, induced apoptosis at 5 microg/ml culture medium in transformed mouse endothelial (F2) cells. Immunoblot analysis using anti-p53 or anti-WAF1 antibodies demonstrated that these two proteins had increased following delta12-PGJ2 treatment in F2 cells. Western blotting analysis using anti-heme oxygenase-1 (heat shock protein (HSP)32) antibody also revealed that delta12-PGJ2 induced HSP32 formation in F2 cells. HSP32 was also induced by heat shock treatment at 43 degrees C for 90 min. In contrast, HSP72 was not induced by heat shock or by delta12-PGJ2 treatment. In agreement with these findings, HSP32 immunofluorescence in the cytoplasm of F2 cells was intensified by delta12-PGJ2 treatment. More intense HSP32 immunoreactivity was similarly observed after heat shock treatment. These results suggest that delta12-PGJ2 caused the apoptotic cell death of F2 cells, which involved a certain process required for p53 or HSP32 induction.

Animals↗
PubMed1998

Basal cell carcinoma cells resemble follicular matrix cells rather than follicular bulge cells: immunohistochemical and ultrastructural comparative studies.

To detail the histogenetic relationship between basal cell carcinoma (BCC) and hair follicles, we immunohistochemically compared BCC cells to follicular matrix cells and follicular bulge cells using a panel of monoclonal antibodies against melanocytes, cytokeratins, subepidermal extracellular matrix components, and bullous pemphigoid (BP) sera, as well as using electron microscopy. Cytokeratin expression patterns were not consistent with the variety in types of cytokeratins and in cases of BCC. The distribution of some extracellular matrix components was not only linear along the interfaces of BCC tumor nests and stroma, and follicular matrix and follicular papilla; granular deposits were also seen in the stroma and follicular papilla, whereas they were only linearly distributed along the follicular bulge. The BP antigens and integrin alpha 6, which were absent in BCC and follicular matrix, were expressed in the follicular bulge area. Electron microscopically, hemidesmosomes were poorly organized in these three tissues, but the lamina densa was incomplete in BCC and follicular matrix, whereas the lamina densa in the follicular bulge area was continuous. These morphologic similarities between BCC and follicular matrix cells, and coexistence of melanocytes in the BCC tumor nest strongly suggest the differentiation of BCC toward the follicular matrix cells.

Basal Cell Carcinoma↗
PubMed1998

Induction of DNA fragmentation by total-body irradiation in murine liver.

Total-body irradiation (TBI) is an accepted modality to treat patients with disseminated tumors. The influence of the treatment on normal tissues is evaluated using mice by measuring the rate of the induction and distribution of apoptosis, as well as DNA fragmentation which occurs in the murine liver within hours of irradiation. Unanesthetized female C3H/He mice were exposed to gamma-ray TBI of 2, 7, and 20 gray (Gy) delivered from 60Co at a dose rate of 114 cGy/min. Frozen sections of livers which were excised from the animals at various times after irradiation were stained by hematoxylin-eosin (H-E) to count numbers of apoptotic cells, or were examined to detect DNA fragmentation. The percentages of apoptotic cells and length of the period during which the maximum levels of the percentages were exhibited showed a dose-dependent increase in the sections stained with H-E. No positive cells for 3'-OH ends of fragmented DNA were found in the liver before TBI, whereas positive cells were observed immediately after irradiation without dose-dependency, these positive cells returned to nearly basal levels after several hours. Positive cells were observed prior to showing apoptosis, suggesting that DNA fragmentation occurs immediately after TBI independent of apoptosis. The difference in the time courses between induction of DNA fragmentation and of apoptosis was not observed in other organs or in the samples treated with the detergent. These results suggested that the 3'-OH ends newly generated by TBI were masked by a detergent-soluble DNA-binding molecule which might be preferentially present in the murine liver.

Animals↗
PubMed1998

Effects of irradiation on telomerase activity in human lymphoma and myeloma cell lines.

The effect of high-dose irradiation on telomerase activity was examined in some human lymphoma (DL40, DL95, DL110) and myeloma (U266) cell lines. The survival rate was reduced in DL40, DL110 and U266 by irradiation. Irradiation, however, showed no effect on the rate of DL95. Telomerase activity was detected in non-irradiated samples of all cell lines, as measured by PCR-based telomeric repeat amplification protocol assay. The telomerase activity increased 2-6.5 fold by irradiation. Especially in DL110, the activation increased in a dose-dependent manner. In the early phase after irradiation, we observed no correlation between telomerase activity and cell viability, suggesting that telomerase-mediated chromosome healing might not be a major cause and/or not sufficiently effective to protect the cells from irradiation.

Cell Line, Tumor↗
PubMed1997

Roles of E- and P-cadherin in the human skin.

The Ca(2+)-dependent cell-cell adhesion molecules, termed cadherins, are subdivided into several subclasses. E (epithelial)- and P (placental)-cadherins are involved in the selective adhesion of epidermal cells. E-cadherin is expressed on the cell surfaces of all epidermal layers and P-cadherin is expressed only on the surfaces of basal cells. Ultrastructural studies have shown that E-cadherin is distributed on the plasma membranes of keratinocytes with a condensation in the intercellular space of the desmosomes. During human skin development P-cadherin expression is spatiotemporally controlled and closely related to the segregation of basal layers as well as to the arrangement of epidermal cells into eccrine ducts. In human skin diseases E-cadherin expression is markedly reduced on the acantholytic cells of tissues in pemphigus and Darier's disease. Cell adhesion molecules are now considered to play a significant role in the cellular connections of cancer and metastatic cells. Reduced expression of E-cadherin on invasive neoplastic cells has been demonstrated for cancers of the stomach, liver, breast, and several other organs. This reduced or unstable expression of E- and P-cadherin is observed in squamous cell carcinoma, malignant melanoma, and Paget's disease, but cadherin expression is conserved in basal cell carcinoma. Keratinocytes cultured in high calcium produce much more intense immunofluorescence of intercellular E- and P-cadherin than those cells grown in low calcium. E-cadherins on the plasma membrane of the keratinocytes are shifted to desmosomes under physiological conditions, and therein may express an adhesion function in association with other desmosomal cadherins. Soluble E-cadherins in sera are elevated in various skin diseases including bullous pemphigoid, pemphigus vulgaris, and psoriasis, but not in patients with burns. Markedly high levels in soluble E-cadherin are demonstrated in patients with metastatic cancers.

Cadherins↗
PubMed1997

Three-dimensional cultures of keratinocytes and an application to in vitro-amyloid production of cutaneous amyloidosis.

Some three-dimensional culture models of the skin were reviewed including our systems using a collagen dermal substitute and a matrix dermal substitute. No obvious junctional structures, such as hemidesmosomes and the lamina densa, were formed between the basal keratinocytes and the dermal substitutes, when the cytoplasmic membrane of the basal keratinocytes directly faced the collagenous materials. On the other hand, when the cytoplasmic membrane of the basal keratinocytes faced the preformed basement membrane, the type IV collagen film, or the extracellular matrix gel, an organized interaction occurred between the basal keratinocytes and the dermal substitute through hemidesmosomes and a rudimentary lamina densa. Keratinocyte differentiation in the suprabasal layers seemed to be closely related to such a basal cell differentiation. Our preliminary examination of the experimental amyloid production by the epidermal sheet from the lesional skin of patients with primary localized cutaneous amyloidosis suggested that the basal cells in the transplanted lesional epidermis produced amyloid fibrils in our in vitro culture model. This is another use of the three-dimensional culture models of the skin in addition to the application of the systems to wound treatment.

Amyloid↗
PubMed1997

Characteristics of mucosal nociceptors in the rat oral cavity: an in vitro study.

Characteristics of mucosal nociceptors were investigated by recording activities from single fibers in the lingual nerve in an in vitro jaw-nerve preparation of rats. We found four subtypes of nociceptors in the medial side gingival area of the oral mucosa in the lower jaw: 11 A delta-high threshold mechanonociceptors (A delta-HTMs), 7 A delta-mechanoheat nociceptors (A delta-MHs), 21 A delta-polymodal nociceptors (A delta-POLYs) and 28 C-polymodal nociceptors (C-POLYs). Thus the majority of the nociceptors was polymodal type (ca. 73% of the recorded fibers), ca. 43% of which consisted of A delta-POLYs scarcely found in the skin but commonly found in the deep tissue, muscle or colon. In contrast to the skin, the size of the receptive field of both A delta and C polymodal types was larger than that of either A delta-HTM or A delta-MH type. The von Frey threshold of all types of mucosal nociceptor was higher than that of the skin, though their heat threshold was almost the same as that of the skin nociceptors. These results show that the mucosal nociceptors are different from the skin nociceptors in the frequency distribution of their types and certain physiological properties.

Action Potentials↗
PubMed1997

CMO I deficiency caused by a point mutation in exon 8 of the human CYP11B2 gene encoding steroid 18-hydroxylase (P450C18).

Corticosterone methyloxidase I (CMO I) deficiency is an autosomal recessive disorder of aldosterone biosynthesis. To determine further the molecular genetic basis of CMO I deficiency, a patient of Turkish origin that suffered from CMO I deficiency was studied. Nucleotide sequencing of the PCR-amplified exons from the genomic DNA of this patient revealed a single point mutation CTG (leucine) CCG (proline) at codon 461 in exon 8 of CYP11B2, which is involved in the putative heme binding site of steroid 18-hydroxylase (P450(C18)). The expression study using a cDNA introducing the point mutation revealed that the amino acid substitution totally abolishes the P450(C18)p3 enzyme activities required for conversion of 11-deoxycorticosterone to aldosterone, even though the mutant product was detected in the mitochondrial fraction of the transfected cells. These results suggest that this point mutation causes CMO I deficiency.

Aldosterone↗
PubMed1997

Detection of p53 gene mutations in fine-needle aspiration biopsied breast cancer specimens: correlations with nuclear p53 accumulations and tumor DNA aneuploidy patterns.

Using the polymerase chain reaction and a single strand conformation polymorphism (PCR-SSCP) analysis, p53 gene mutations have been examined preoperatively in aspirated biopsy specimens from 22 breast cancers. In eight (36%) of the studied cases, abnormal bands indicating mutations were detected and were more frequently present in common invasive breast carcinomas. Eight of the breast cancer cases were found to be positive for mutations: direct DNA sequencing confirmed eight mutations and revealed G to A and A to G nucleotide changes in five (63%) and two (25%) cases, respectively. The mutations that were localized at the CpG site of the gene were seen in three cases. Additionally, an immunohistochemical investigation of the presence of the p53 protein and a DNA flow-cytometrical analysis of the 22 resected breast cancers were also performed. Nuclear p53 protein accumulations and a DNA aneuploidy pattern were detected in 11 (50%) cases and in 16 (73%) cases, respectively, and both significantly correlated with p53 gene mutations (P < 0.01 and P < 0.001, respectively; Fisher's exact test). In contrast, in five cases of a breast cancer with a lower histologic grade, no p53 gene mutations, nuclear p53 protein accumulations, or DNA aneuploidy patterns were detected. These results thus suggest that p53 gene mutations, nuclear accumulations of the p53 protein, and a DNA aneuploidy pattern are events that occur with close relationship in the progression of a breast cancer, and that p53 abnormalities appear to correlate with a high grade of the malignancy. Therefore, the detection of p53 gene mutations in aspirated biopsy specimens of breast cancers may be helpful for an accurate and rapid cytological diagnosis, which reflects the prognosis.

Adult↗
PubMed1997

Sulfated sialyl Lewis X, the putative L-selectin ligand, detected on endothelial cells of high endothelial venules by a distinct set of anti-sialyl Lewis X antibodies.

Endothelial cells of high endothelial venules (HEV) in human peripheral lymph nodes expressed a distinct type of sialyl Lewis X antigen, which was detected preferentially with a set of anti-sialyl Lewis X antibodies, 2F3, 2H5 and HECA-452 in immunohistochemistry, while another set of anti-sialyl Lewis X antibodies, FH-6 and CSLEX-1, failed to detect it. The adhesion of cells expressing L-selectin to HEV was inhibited by members of the former set of antibodies in Stamper-Woodruff assays performed on frozen sections of human peripheral lymph nodes. Transfection of a cultured endothelial cell line with a human alpha1-->3 fucosyltransferase, Fuc-T VII, resulted in the expression of a distinct type of sialyl Lewis X antigen having the reactivity similar to that of HEV; i.e., the antigen appearing on the transfectant clone was detectable only with the set of 2F3, 2H5 and HECA-452, but not with the set of FH-6 and CSLEX-1. Treatment of transfectant cells with sodium chlorate, a metabolic inhibitor of sulfation, resulted in reactivity to the members of the latter set of antibodies, suggesting that sulfation of sialyl Lewis X moiety was the cause of the discrepancy in the reactivity of the anti-sialyl Lewis X antibodies. When tested against various authentic sulfated sialyl Lewis X determinants, 6-sulfo sialyl Lewis X and 6,6'-bis-sulfo sialyl Lewis X were found to be reactive to the antibodies, 2F3, 2H5 and HECA-452, but not with antibodies FH-6 and CSLEX-1, suggesting that the distinct type of sialyl Lewis X determinant on the HEV endothelial cells and Fuc-T VII-transfected endothelial cell clone are mainly 6-sulfo and/or 6,6'-bis-sulfo sialyl Lewis X determinants.

Animals↗
PubMed1997

Failure to express the P-selectin gene or P-selectin blockade confers early pulmonary protection after lung ischemia or transplantation.

Endothelial P-selectin expression contributes to the first wave of neutrophil (polymorphonuclear leukocyte: PMN) influx in several inflammatory conditions. Although remote tissue ischemia, such as a crush injury to the hindlimb, may result in P-selectin-mediated pulmonary leukosequestration, it is not known whether the lungs exhibit a similar response after hypothermic preservation or when subjected to a direct ischemic insult. To determine if P-selectin may mediate early primary graft failure, left lungs harvested from male Lewis rats were preserved for 6 hr at 4 degrees C and transplanted orthotopically into isogeneic recipients. Recipients immunodepleted of PMNs before transplantation demonstrated improved graft function; pulmonary vascular resistance was reduced approximately 6-fold, arterial oxygenation was increased approximately 3-fold, and recipient survival was increased approximately 4-fold (P < 0.05, 0.05, and 0.005, respectively). Administration of a blocking anti-P-selectin IgG 10 min before reperfusion diminished graft PMN infiltration and resulted in improved graft function and recipient survival compared with controls. To establish the role of P-selectin in normothermic pulmonary ischemia, mice were subjected to temporary left pulmonary artery ligation. After functional removal of the nonischemic right lung, mice deletionally mutant for the P-selectin gene (P-selectin-/-) exhibited reduced PMN infiltration (approximately 2-fold), improved arterial oxygenation (approximately 2-fold), and improved survival (approximately 3-fold) compared with P-selectin +/+ control mice (P < 0.05, 0.01, and 0.05, respectively). These studies isolate and identify the central role of a single gene product (P-selectin) in early PMN recruitment and tissue injury after frank pulmonary ischemia and in the setting of lung transplantation after hypothermic preservation.

Animals↗