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Biomedical subjects

K S Chang

Publications and source records attributed to K S Chang.

At least 145 records · Page 8Linked to original sources
PubMed1982

possible role of a retrovirus in the expression of tumor-specific antigens of the Meth A sarcoma.

The serologically defined tumor-specific surface antigen (TSSA) of the chemically-induced BALB/c Meth A sarcoma, highly restricted to one of 20 sarcomas of BALB/c origin, has been detected on a Moloney murine sarcoma virus (Mo-MuSV)-transformed BALB/c 3T3 cell lines, designated IIA(v). The immunogenicity of the IIA(v) cell in tumor-rejection assays was specific for the Meth A sarcoma, supporting the evidence for a close relationship between the TSSA and the tumor-associated transplantation antigen (TATA) of this tumor. Infection of SC-I cells with retroviruses present in cultured filtrates of IIA(v) cells resulted in Meth A antigen expression. The retroviruses associated with Meth A antigen expression have been tentatively identified as replication and/or transformation-defective XC- MuLV. The possible roles of Mo-MuSV and cellular genes of the BALB/c strain of mice in the expression of the Meth A antigen are discussed.

Animals↗
PubMed1982

Bioelectric activity in the rabbit ear regeneration.

A 1-cm-diameter hole was punched through rabbits' ears. The surface potentials during wound healing of regenerating (normal) and partially and nonregenerating (decartilaged) ears were measured. The time sequence of these surface potentials were similar to those reported to occur in regenerating amphibians forelimbs. A small positive potential was observed for about 1 week, and this was followed by a larger negative potential of up to 20 mV, with different durations. The duration of the positive potential was about the same as which was observed in amphibians. The duration and the amplitude of the negative potential were greatest for completely regenerating ears with overgrowth, smaller for partially regenerating ears, and smallest for the nonregenerating ears. The surface potential was localized. If a nipple-shaped outgrowth developed after the hole was closed, the surface potential was observed only on this outgrowth; immediately outside it, the potential was normal. We concluded that the negative bioelectric activity accompanies growth, and while growth continues, negative bioelectric potential continues.

Animals↗
PubMed1982

Modulation of natural killer sensitivity of murine trophoblast cells by tumor promoter and interferon.

The in vitro established lines of murine placental trophoblast cells showed little membrane expression of H-2 antigens and a high degree of sensitivity to natural killer (NK)-cell-mediated cytotoxicity. This NK-sensitivity was decreased either by short-term treatment of these cells with murine interferon (IFN) or by culture for more than 4 days in the presence of a tumor promotor, 12-O-tetradecanoylphorbol-13-acetate (TPA). This effect of TPA was reversible after removal of TPA from the culture medium. However, IFN treatment of trophoblast cells cultured previously in TPA medium resulted in restoration of NK-sensitivity to the original level exhibited by cells untreated with IFN or TPA. The mechanism for this antagonistic effect is not clear. The decrease in NK-sensitivity of IFN- or TPA-treated trophoblast cells was not due to the loss of NK-recognition membrane structures, or to induction of prostaglandin which elevates cyclic-AMP levels. Inhibition of protein synthesis by cycloheximide restored the NK-sensitivity or TPA-treated trophoblast cells, indicating the possible contribution of de novo synthesized protein(s) which could confer NK-resistance. The TPA-treated trophoblast cells became more tumorigenic, producing larger tumors and a higher mortality than the untreated controls when inoculated into mice. The possible roles of NK cells in trophoblastic diseases and feto-maternal relationships are discussed.

Animals↗
PubMed1982

Isolation and characterization of polyoma virus mutants which grow in murine embryonal carcinoma and trophoblast cells.

Mouse trophoblast cell lines established from cultured midterm placenta and a cell line obtained from cultured blastocyst resemble trophectoderm cells. These cells are resistant to infection by wild-type polyoma virus. We have isolated six polyoma virus mutants capable of growing in trophoblast cell lines. Restriction enzyme analyses and marker rescue experiments revealed that the genetic changes necessary for the growth of these mutants ( PyTr mutants) in trophoblast cells were located in a regulatory region of the genome between the origin of viral DNA replication and the region encoding the viral structural proteins. PyTr mutants are, therefore, similar to PyEC mutants, described by others, which are able to grow in embryonal carcinoma cell lines such as F9 or PCC4. The nucleotide sequence of two independently obtained PyTr mutants has an identical 26-bp deletion from nucleotide 5131 to 5156. This deleted region is replaced by either the sequence GGGA or by viral DNA sequences that flank this deletion. PyECF9 mutants grow well in trophoblast and trophectoderm cells, but PyTr mutants do not grow in F9 or PCC4 cells.

Animals↗
PubMed1982

The use of sinusoidally changing workloads as an aid to identify dynamic properties of physiological systems.

The methodology of using frequency analysis in order to identify types of system(s) is discussed. A number of models with their characteristic Nyquist plots are presented graphically, to facilitate the identification of various types of systems by pattern recognition. A small series of measurements of oxygen consumption and heart rate has been carried out to illustrate the possibilities and limitations of the use of frequency analysis in exercise physiology. With a step function method one can only establish whether a system has multiple components in parallel or not, but with the frequency analysis method one can identify whether a system has multiple components in parallel or in series. It was found that under moderate exercise, the response of oxygen consumption to exercise is a system with multiple components in series, but the response of heart rate to exercise is a system with multiple components in parallel. The data that were obtained are in agreement with those produced by other authors, but the curves to fit the observed data were obtained using second order linear transfer functions.

Adult↗
PubMed1982

Unscheduled DNA synthesis in rat liver after gastric administration of halothane.

Unscheduled DNA replication occurred in response to halothane administered to rats by stomach tube. This response was observed under a narrow range of experimental conditions that included pretreatment with phenobarbital and a short interval between barbiturate and anesthetic administration. Under the conditions of the experiment, hepatic necrosis was not demonstrable.

Animals↗
PubMed1982

Characterization of xenotropic and dual-tropic type C retroviruses isolated from Abelson tumour.

Tumours induced in Balb/c mice by Abelson virus complex were found to contain a xenotropic virus (A-X-MuLV) and an NB-tropic, dual-tropic virus (NBX), in addition to the Moloney leukaemia virus (M-MuLV) and the defective, transforming Abelson virus genome. Both A-X-MuLV and NBX virus were presumably present in a genomically masked form and could be recovered only by co-cultivation of tumour cells with permissive cells. Only about 0.87% and 0.13% of the viruses in the co-culture supernatant represented A-X-MuLV and NBX virus respectively; the majority were M-MuLV. The NBX virus acted more efficiently than the HIX virus (Fischinger et al., 1975) as helper to rescue murine sarcoma virus (MSV) from S+L-cells of hamster, rat and mouse origin, whereas the converse was true for those of cat and human origin. The interference and nuetralization patterns suggested that the NBX virus was an env gene recombinant between A-X-MuLV and M-MuLV. The fact that NBX virus cross-reacted in radioimmunoassays with gp70s of both M-MuLV and Balb: virus-2 provides evidence for the recombinant nature of the NBX gp 70-coding gene which was probably derived from both M-MuLV and a virus similar to Balb: virus-2 or A-X-MuLV. The presence of a unique antigenic determinant on the gp70 of NBX virus is also suggested. Both A-X-MuLV and NBX virus cross-reacted with type-specific p12s of M-MuLV and Balb: virus 2- suggesting that the gag gene coding for p12 of NBX virus was derived from the A-X-MuLV, which was itself a recombinant, its p12-coding gene being derived from both Balb: virus-2-like virus and M-MuLV. The NBX virus was not oncogenic when tested in newborn Balb/c mice.

Abelson murine leukemia virus↗
PubMed1982

Ten-year pathological study of Beall mitral valve prostheses.

Detailed pathological studies are reported on 20 cloth-covered Beall mitral valve prostheses, which had to be removed for valve failure nine months to 10 years after implantation. Results in all patients except one indicated that there was a progressive and persistent granulomatous reaction that continued up to at least 10 years. Although the rate of tissue ingrowth into the valve decreased with time, the total volume of tissue formation increased. Cloth wear and disruption and deformity of the teflon discs was frequently seen. In these 20 valves the desired result--namely, the complete and smooth endothelialisation of the prosthesis--was certainly not achieved.

Adult↗
PubMed1981

Carcinomas induced by cell lines cultivated from normal mouse placentas.

Cell lines have been established from placentas of various strains of mice by in vitro cultivation. The established lines appear to be trophoblast cells as judged from their production of gonadotropin-like substance and their production of gonadotropin-like substance and steroid hormones. The cell lines lack detectable H-2 antigen, Fc receptor sites, Thy 1 and antigen and surface immunoglobulin determinants. In addition, the cells are resistant to murine type-C RNA tumor virus infection. The resistance is due to a block of viral replication after the stages of viral adsorption and penetration. The cell lines induced carcinomas after injection into adult mice of original host strains. Usually at least 2 x 10(6) cells are required to induce tumors by i.p. or s.c. injection. Transplantation of the tumor cells to various strains of mice revealed that some strains accepted and some strains rejected the transplant. Genetic crossings between susceptible and resistant mouse strains indicate that susceptibility to transplantation of tumor is determined by a single pair of dominant autosomal genes.

Animals↗
PubMed1981

Fungal endocarditis complicated by mycotic aneurysm of sinus of Valsalva, interventricular septal abscess, and infectious pericarditis: unique M-mode and two-dimensional echocardiographic findings.

A 26-year-old male with fungal aortic endocarditis is presented in whom unique M-mode and two-dimensional echocardiographic findings permitted a diagnosis of mycotic aneurysm of right sinus of Valsalva and ventricular septal abscess preoperatively. The aneurysm was excised, and the affected aortic and tricuspid valves were replaced with valve prostheses.

Abscess↗
PubMed1981

Giant Lambl's excrescences of papillary muscle and aortic valve: echocardiographic, angiographic, and pathologic findings.

A 54-year-old female with rheumatic heart disease was found to have a mass in the left ventricle by echocardiography and angiography. Subsequently, giant Lambl's excrescences of papillary muscle and aortic valve were confirmed by operation and pathologic examination. Possible complication from cardiac catheterization could be avoided by the utilization of echocardiography prior to catheterization.

Aortic Valve↗
PubMed1981

Ecotropic and xenotropic type C retroviruses associated with reticulum cell neoplasms of SJL/J mice.

An ecotropic type C retrovirus (D1-MuLV) isolated from SJL/J mice was injected into neonatally thymectomized SJL/J mice. There was no acceleration of development of reticulum cell neoplasm (RCN) in these mice as compared with the control, uninoculated but similarly thymectomized group. The incidence of RCN at 10 and 11 months after injection was 14.6% and 12.5% respectively. Two female mice inoculated with D1-MuLV developed mammary adenocarcinoma. There was persistence of high titres of the ecotropic virus associated with RCN and mammary tumour of SJL/J mice. Xenotropic virus (X-MuLV) was detected in spleens of normal SJL/J mice at ages 6 and 12 months (60% and 80% respectively) but not at other ages. The X-MuLV isolated from SJL/J mouse embryo cell cultures treated with 5-iodo-2'-deoxyuridine (SJL-MEF-X-MuLV) and that isolated from a spontaneous RCN (SJL-RCN-X-MuLV) were compared with NZB-X-MuLV (NZB mouse origin) and AT124-X-MuLV (NIH Swiss mouse origin) in regard to their host range, ion and primer-template preference by reverse transcriptase, virus interference and neutralization characteristics. Cross-neutralization and gp70 competitive radio-immunoassays showed that D1-MuLV is more closely related to AKR-MuLV than to Rauscher-MuLV and appears to share some virus envelope antigens with SJL-X-MuLVs. The type-specific gag gene product (p12) from Balb:virus-2 and NZB-X-MuLV was used in competitive radioimmunoassay, and SJL-RCN-X-MuLV was found to be more closely related to Balb:virus-2 (MuLV-X alpha) than to NZB-X-MuLV (MuLV-X beta).

Animals↗
PubMed1980

Natural killer cell activity associated with reticulum cell neoplasms.

A marked increase in natural killer (NK) activity is observed with lymphoid cells prepared from SJL/J mouse spleen and lymph nodes, in which a transplantable reticulum-cell neoplasm (RCN) is growing. The killer cells are non-adherent, non-phagocytic, relatively resistant to X-ray, and scarcely or only partially inactivated by treatment with anti-Thy 1.2 serum and complement. The killer activity is directed against a wide variety of tumor target cells, not requiring homology in histocompatibility, but is selective and not indiscriminate. Kinetics of in vivo development on NK activity, competitive inhibition of in vitro cytotoxicity by target cells and their membrane extracts are described. The NK activity appears to increase in parallel with the infiltration and growth of RCN in these organs. No such augmented NK activity was observed with other types of tumors that grew in these organs of SJL/J mice. (C57BL/6 X SJL/J)F1 mice pretreated with silica to abrogate Hh restriction and subsequently injected with RCN of SJL/J (H-2s) origin supported the growth of transplanted RCN. The high NK activity associated with this RCN was markedly reduced by in vitro treatment with anti-H2b serum plus complement, indicating the host origin of NK cells. However, the close association of RCN growth with elevated NK activity may indicate a special function of RCN in promoting NK activity by an unknown mechanism(s) of cellular interactions.

Animals↗
PubMed1980

Solid dispersion of morphine-tristearin with reduced presystemic inactivation in rats.

Solid dispersions of morphine in tristearin, beta-sitosterol, and cholesterol were prepared by evaporation of their ethanol solutions. Weight ratios of morphine-lipid of 1:1, 1:3, and 1:4.5 were prepared. Dissolution studies of the solid dispersions and morphine were conducted in a simulated GI medium at 37 degrees. The release rates of morphine from the tristearin dispersions were the slowest. The 1:1 morphine-tristearin dispersion was administered orally to rats. Free and total morphine levels in rat urine were determined by spectrofluorometric and enzymatic immunoassay procedures, respectively. The morphine-tristearin dispersion yielded a higher percentage of free morphine after 24 and 48 hr as compared with morphine and its sulfate.

Animals↗