PubMed Health⌕ Search

Biomedical subjects

K Toh

Publications and source records attributed to K Toh.

14 recordsLinked to original sources
PubMed2000

Fibrous tissue ingrowth and attachment to porous tantalum.

This study determined the soft tissue attachment strength and extent of ingrowth to a porous tantalum biomaterial. Eight dorsal subcutaneous implants (in two dogs) were evaluated at 4, 8, and 16 weeks. Upon retrieval, all implants were surrounded completely by adherent soft tissue. Implants were harvested with a tissue flap on the cutaneous aspect and peel tested in a servo-hydraulic tensile test machine at a rate of 5 mm/min. Following testing, implants were dehydrated in a solution of basic fuschin, defatted, embedded in methylmethacrylate, and processed for thin-section histology. At 4, 8, and 16 weeks, the attachment strength to porous tantalum was 61, 71, and 89 g/mm respectively. Histologic analysis showed complete tissue ingrowth throughout the porous tantalum implant. Blood vessels were visible at the interface of and within the porous tantalum material. Tissue maturity and vascularity increased with time. The tissue attachment strength to porous tantalum was three- to six-fold greater than was reported in a similar study with porous beads. This study demonstrated that porous tantalum permits rapid ingrowth of vascularized soft tissue, and attains soft tissue attachment strengths greater than with porous beads.

Animals↗
PubMed1995

Seroepidemiological survey of feline retrovirus infections in cats in Taiwan in 1993 and 1994.

In order to investigate the prevalence of infections with three feline retroviruses feline immunodeficiency virus (FIV), feline leukemia virus (FeLV) and feline syncytial virus (FSV) in Taiwan, we collected a total of 75 blood samples from cats from veterinary hospitals, a breeding cattery and a homeless shelter in 1993 and 1994. We examined the presences of anti-FIV and FSV antibodies and FeLV-p27 antigen in these samples by the indirect immunofluorescence and/or enzyme-linked immunosorbent assays. All of the serum samples positive for FIV were obtained from homeless cats and the overall FIV positive rate was 4%. The overall positive rates of FSV and FeLV were 28% and 1.3%, respectively. From these results, together with previous seroepidemiological surveys by others, it was revealed that the prevalence of FIV and FeLV infections appeared to be lower in Taiwan than in the United States or Japan. In contrast, the prevalence of FSV infection in Taiwan was as high as that in Japan.

Animals↗
PubMed1987

[Clinical application of the subrenal capsule assay (SRCA) and related problems].

Subrenal capsule assay was performed on 35 fresh cancer tissue samples (13 stomach, 7 colon, 8 breast and 7 others) against MMC, 5-FU, ADM, CPA, MTX and cDDP employing normal immunocompetent ddY mice following Bogden's original method. Evaluability was 86% (30/35). Sensitivity was between 32 and 46% for each of the drugs except cDDP. Some organ-specific variations were noted between gastro-colic cancers and breast cancers with regard to chemosensitivity spectrum and also individual cases of the same histological type did not show a uniform one. Gastric cancer had the highest activity. The assay/clinical correlations were evaluable in 10 cases where 6 cases on active agents achieved two PR, two NC and PD, while all 4 cases on non-active agents showed PD. Histological analysis of implants, however, disclosed the following inherent problems: First, there was heterogeneity in tissue fragments due to the variable amounts of stroma; Second, apparent host reactions were seen in the untreated groups on the 6th day, accompanying marked damage to cancer cells. In contrast, in drug-treated groups, host reactions in most of them were suppressed and cancer cells were seen frequently in considerable amounts. This fact implies the mechanism that SRCA is based on, in spite of the xenograft immune; Third, there was some discordance between the macroscopic and microscopic findings. SRCA is assumed to be appliable to individual clinical cases up to a certain level which should be determined by histological analysis as well as by accumulation of clinically correlated cases.

Animals↗
PubMed1979

Separation of cell-dependent antibody (CDA) and inhibitory antibody by protein-A affinity chromatography and the effect of fractions on antibody-dependent cellular cytotoxicity (ADCC).

The nature of cell-dependent antibody (CDA) and the mechanism of inhibition of antibody-dependent cellular cytotoxicity (ADCC) were studied in the ADCC assay system in which culture cells of methylcholanthrene-induced rat fibrosarcoma (KMT-50) were used as target cells, xenogeneic antiserum (rabbit anti-KMT-50) as the CDA, and human peripheral blood leucocytes (PBL) as effector cells, respectively. By using protein-A Sepharose CL-4B affinity column chromatography of rabbit anti-KMT-50 serum, CDA was shown to bind protein A. Complement dependent-cytotoxicity (CDC), however, was demonstrated in both the adsorbed fraction (eluate) and the non-adsorbed fraction (effluent) to protein A from the same affinity column chromatography. These data confirmed that CDA was IgG with an intact Fc portion. Inhibition of ADCC occurred by pretreatment of effector cells with rabbit anti-effector (human PBL) serum even with extremely small amounts of antiserum. Such inhibition was demonstrated with the eluate but not with the effluent from protein-A Sepharose CL-4B affinity column chromatography of rabbit anti-effector serum. F(ab')2 fragments of the same eluate (IgG) did not inhibit the ADCC activity. These data showed that the inhibition of ADCC was induced by the blocking of Fc receptors of effector cells with the Fc portions of IgG in anti-effector serum. The data obtained indicate the usefulness of protein A in separation and analysis of CDA and in investigation of the inhibitory mechanisms of ADCC.

Animals↗
PubMed1977

A simple method of cell-mediated cytotoxic assay by postlabeling of tritiated thymidine.

The cytotoxic reaction of effector cells on target cells was performed on cover slips which were set in a petri dish so as to be interposed from the dish surface through the bases of the slide glasses. After incubation, the target cells remaining on the cover slips were pulse-labeled with 3H-TdR for 45 min. Subsequently, the cover slips were removed from the bases, and dipped in cold 5% TCA to be freed from non-incorporated isotopes. The residual target cells adhering on the cover slips were counted without being removed. By this assay system, the specific or non-specific cytotoxicity of lymphocytes or macrophages was easily demonstrated with reliability.

Animals↗
PubMed1977

Inhibition of cellular DNA synthesis by rat peritoneal macrophages.

The DNA synthesis in syngeneic, allogeneic and xenogeneic cells was inhibited by peritoneal macrophages of normal WKA rats. This inhibitory effect of macrophages was found to be mediated by a soluble factor (MfID) released into a culture medium from macrophages which was heat-stable and non-dialyzable. The MfID was also responsible for the inhibtion of lymphocyte DNA synthesis by MLC reaction. The action of MfID was indicated to suppress rather than to kill cell growth. It was interpreted that the inhibitory effect of macrophages on cellular DNA synthesis is their inherent property and macrophages may play the role of regulating the proliferation of lymphocytes and other cells.

Animals↗
PubMed1976

Inhibition of tumor growth in vivo and in vitro by macrophages from rats treated with a streptococcal preparation, OK-432.

The role of macrophages from rats treated with a streptococcal preparation (OK-432) for inhibition of syngeneic tumor growth was examined both in vivo and in vitro. Treatment of rats with OK-432 intraperitoneally resulted in a transient inhibition of ascites tumor growth and concomitant increase in survival time. Peritoneal exudate cells from these rats completely suppressed tumor growth when admixed with tumor cells and transferred subcutaneously to syngeneic recipient rats. No such effect was observed with tumor cells from saline-treated control rats. The macrophages were responsible for the neutralization of tumor growth, since the removal of adherent cells from peritoneal exudate cells of rats treated with OK-432 resulted in the abrogation of their antitumor activity. To further investigate the antitumor activity of macrophages, an in vitro cytotoxicity assay was carried out on several tumor cell lines. A complete target cell destruction was brought about by macrophages from the rats treated with OK-432 but not from the control animals. The tumor cytotoxicity mediated by macrophages activated with OK-432 was regarded as non-specific because they could damage all the target cell lines tested.

Animals↗
PubMedDate not supplied

TPH gene may be associated with suicidal behavior, but not with schizophrenia in the Korean population.

Tryptophan hydroxylase (TPH) is a rate-limiting enzyme in the biosynthesis of serotonin. This study was designed to examine whether A218C polymorphism, which has been identified in intron 7 of the TPH gene, may be associated with schizophrenia or the suicidal behavior of schizophrenics in the Korean population. TPH genotypes were determined in DNA samples from 217 schizophrenics and 236 healthy volunteers. Among the schizophrenic group, 27 patients had a history of suicidal behavior. Genomic DNA was amplified by a polymerase-chain-reaction-based method and restricted by Nhel. A218C polymorphism was associated with a history of suicidal behavior in schizophrenics. This finding suggests that the TPH gene or a gene in its vicinity may influence suicidal behavior in schizophrenics. However, genotypic and allelic distrubutions of this polymorphism did not significantly differ between schizophrenics and controls.

Adult↗