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Biomedical subjects

S Shin

Publications and source records attributed to S Shin.

At least 199 records · Page 11Linked to original sources
PubMed1987

Angiotensin II-induced increase in inositol 1,4,5-trisphosphate in cultured rat mesangial cells: evidence by refined high performance liquid chromatography.

Angiotensin II-induced change in inositol phosphates were studied in cultured rat mesangial cells prelabeled with [3H]myo-inositol. By using anion-exchange high performance liquid chromatography, we could analyzed the change in inositol mono-, bis-, and tris-phosphate more rapidly and easily with higher resolution than the previously reported methods. Angiotensin II rapidly increased inositol 1,4,5-trisphosphate and inositol 1,4-bisphosphate within 15 sec, followed by an increase in inositol 1-monophosphate at 30 sec. Angiotensin II-induced increases in inositol phosphates were dose-dependent and completely blocked by saralasin. These results indicate that angiotensin II induces the production of inositol phosphates including inositol 1,4,5-trisphosphate, an intracellular Ca2+-releasing factor, in cultured rat mesangial cells.

Angiotensin II↗
PubMed1986

Decreased tumorigenicity correlates with expression of altered cell surface carbohydrates in Lec9 CHO cells.

To investigate a role for surface carbohydrates in cellular malignancy, 15 different glycosylation-defective CHO cell mutants were examined for their tumorigenic and metastatic capacities after subcutaneous injection into nude mice. Most of the glycosylation mutants displayed similar or slightly decreased tumorigenicity compared with parental CHO cells. Neither parental CHO cells nor any of the mutants were observed to metastasize. However, independent isolates of one mutant type, Lec9, showed a dramatic reduction in tumor formation. The altered carbohydrates expressed at the surface of Lec9 cells appeared to be responsible for their loss of tumorigenicity, because revertants for lectin resistance were able to form tumors, and a double mutant (Lec9.Lec1) that expressed a Lec1 glycosylation phenotype also formed tumors. Finally, Lec9 cells were able to form tumors in gamma-irradiated nude mice, suggesting that recognition by an irradiation-sensitive host cell(s) was responsible for their reduced tumorigenicity in untreated nude mice.

Animals↗
PubMed1986

Quantitative and qualitative characterization of human cancer-associated serum glycoprotein antigens expressing fucosyl or sialyl-fucosyl type 2 chain polylactosamine.

The quantity of tumor-associated antigens carrying type 2 chain polylactosamines with four types of fucosyl determinants, LeX (X-hapten), poly-LeX, sialyl LeX, and LeY (Y-hapten), present in sera of patients with various malignant and non-malignant disorders, as well as the qualitative chemical properties of the carrier molecules in sera, have been investigated using four monoclonal antibodies, each of which defines one of these determinants. The following findings are of particular importance: the serum levels of LeX defined by antibody FH2 and poly-LeX defined by ACFH18 in patients with cancer were occasionally high (incidence about 10%); however, the majority of patients did not show elevated levels; the serum level of the antigen, defined by monoclonal antibody FH6 (termed sialyl LeX-i since this determinant is carried by i antigen), was significantly high in patients with cancers originating from organs from which adenocarcinomas often develop. For example, among various types of lung cancer, only adenocarcinoma but not squamous cell carcinoma, small cell carcinoma, or large cell carcinoma showed a high level of sialyl LeX-i antigen in sera. The incidence of high antigen levels in sera of patients with adenocarcinomas of lung was as high as 76% of the observed cases; the serum level of Ley (Y-hapten) was frequently high in patients with hepatoma (incidence, 34%); sialyl LeX-i antigen was separated on gel filtration as a glycoprotein with an average molecular weight greater than 10(6). It was characterized by its susceptibility to basehydrolysis, Pronase digestion, and sialidase and endo-beta-galactosidase treatment and is assumed to be a high molecular weight mucin-type glycoprotein; sialyl LeX-i antigen expressed in sera of patients with cancer was soluble in perchloric acid, while the same antigen in sera of patients with noncancerous diseases and normal subjects was mostly insoluble in perchloric acid. LeX, a poly-LeX, and essentially all LeY antigens in sera of patients with cancer were perchloric acid-insoluble.

Antibodies, Monoclonal↗
PubMed1985

Whole milk extender with antibiotics to eliminate Campylobacter fetus from frozen bovine semen.

Fresh bovine semen was contaminated with five strains of Campylobacter fetus at 10(5) to 10(6) organisms per ml of semen. The contaminated semen was processed to contain 500 units of polymyxin B, 500 units of penicillin G, and 1000 micrograms of streptomycin sulfate per ml, incubated at 35 degrees C for 10 min, and added then to whole milk extender with like units of antibiotics for further processing. Both a low and high initial sperm count requiring extension rates 1:7 and 1:39 were studied. Specimens for bacterial viability were processed for culture prior to adding bacteria, 100 min after initial antibiotic treatment, prior to freezing, and after thawed semen was centrifuged and washed to remove extender and antibiotic residue. All strains of Campylobacter fetus were not viable 6 h postantibiotic treatment prior to freezing. All nonantibiotic treated controls were viable after thawing and washing. Removal of antibiotics from thawed semen by centrifugation and washing indicated that antibiotics had bactericidal rather than only bacteriostatic activities against Campylobacter fetus.

Animals↗
PubMed1985

[Blood volume measurement of newborn using stable isotope 50Cr].

A technique for the blood volume measurement of newborns was established in which nonradioactive 50Cr was used in patients for whom radioactive labels were not advisable. The red blood cells (RBC) in the newborn's blood withdrawn from umbilical cord after birth were tagged with enriched stable isotope 50Cr (96%, normal abundance 4.3%) and reinjected into the newborn. Blood samples (0.5 ml) were withdrawn at 30 min and thereafter at 6, 12, 24, 48, 72 and 120 hours old. Samples were centrifugalized and portion of RBC was then freeze-dried, weighed and sealed into polyethylene sheet bag together with 50Cr standard. Neutron irradiation was performed in the reactors of the JAERI with thermal neutron flux 5 X 10(13), 2 X 10(13), 8 X 10(13) cm-2s-1 at JRR-2, -3 and -4 respectively for 20 min and samples were left for about two weeks after irradiation. Induced radioactivity (51Cr, 59Fe) of the sample was measured with a Ge(Li) gamma-ray detector system and 4096 channels pulse height analyzer. Analysis of activity data was carried out by BOB-76 code. The RBC and total blood volume of the newborn was calculated using an isotopic dilution technique. We have investigated on tagging efficiency of 50Cr to RBC, washing effect and dilution rate by 50Cr content or 51Cr/59Fe ratio. Significant difference was observed in the total blood volume of newborns depending on the delivery style and in addition, it changed dynamically along the time elapsed after birth.

Blood Volume Determination↗
PubMed1983

Tumorigenicity of SV40-transformed human and monkey cells in immunodeficient mice.

Human cells transformed in vitro by SV40 to the anchorage-independent state rarely form tumors in nude mice and therefore constitute an important exception to the otherwise tight correlation between anchorage independence and cellular tumorigenicity. In this paper we explore a number of possible explanations for this unusual situation. We find that the phenomenon is not restricted to human cells but includes monkey cells as well. The nontumorigenic phenotype of the primate SV40 transformants is highly stable. We are unable, through selection of ever more anchorage-independent lines, to generate a primate SV40 transformant which will grow as a tumor in even the most immunologically crippled animals. One tumor was obtained from SV80 (an SV40-transformed human cell line) following injection into a mouse deficient in both T and B cell functions. However, cell lines derived from this tumor are not significantly more tumorigenic than the SV80 parent. This low incidence of tumor formation is not due to the fact that the primate cells are transformed by nononcogenic defective viral genomes nor to a nutritional inadequacy of the host animal for the growth of human cells. Although a T cell-independent mechanism may be the major mechanism involved in tumor suppression, it is unlikely that this completely accounts for the general lack of tumor growth by most of these cells. It appears that the interaction of SV40 (a primate virus) with primate cells may be intrinsically less oncogenic than its interaction with rodent cells.

Animals↗
PubMed1983

Transcription of the Epstein-Barr virus genome in productively infected cells.

Transcription of the genome of Epstein-Barr virus in productively infected B95-8 cells was studied. Dot blot hybridization of cDNA prepared from cytoplasmic viral poly(A)RNA with 28 different cloned BamHI fragments of EBV DNA indicated that the patterns of viral genome transcription were similar in control and TPA-treated cells. However, three fragments, BamHI I, R, and Z, appeared to be newly induced in TPA-treated cells, as no significant level of transcription of these fragments was observed in control cells. In contrast, there was no detectable transcription from fragments BamHI P, a, and b even in cells treated with TPA. The size of virus-specific RNA was determined by agarose gel electrophoresis followed by Southern blot hybridization using radioactive BamHI cloned EBV DNA fragments as probes. Sixty-eight cytoplasmic poly(A)RNA species, ranging in size from 0.1 to 2.8 megadaltons, were detected by this procedure.

Animals↗
PubMed1983

Phosphonoacetic acid-resistant RNA of Epstein-Barr virus in productively infected cells.

The transcription of Epstein-Barr virus genome in productively infected B95-8 cells in the presence or absence of phosphonoacetic acid (PAA) was studied. Twenty-eight species of cytoplasmic poly(A)-containing virus mRNA were identified as PAA resistant. Some of these viral mRNAs were not detected in the absence of PAA. The most actively transcribed fragments of cloned EBV DNA in the presence of PAA were BamHI H (map unit 29.1-32.5) and M (47.3-50.3). The treatment of TPA-induced B95-8 cells with cycloheximide abolished most cytoplasmic viral poly(A) RNAs, and only three species of viral mRNA (0.7, 1.0, and 1.6 megadaltons) were detectable by hybridization with the BamHI M fragment.

Animals↗
PubMed1983

Evidence from opiate binding studies that heroin acts through its metabolites.

The relative affinity to opiate receptors of heroin, 6-acetylmorphine and morphine was estimated by determining their ability to displace specifically bound 3H-naltrexone from rat brain opiate binding sites. In vitro hydrolysis of heroin to 6-acetylmorphine was monitored in the binding assay filtrate by use of a quantitative HPLC procedure. The rate of heroin hydrolysis was significantly slower at 0 degrees C than at 37 degrees C. The displacement of 1 nM 3H-naltrexone by unlabeled ligand at concentrations ranging from 7 to 500 nM was measured at 0 degrees C for 120 minutes, yielding IC50 values of heroin = 483 nM, 6-acetylmorphine = 73 nM and morphine = 53 nM. When the binding data for heroin were recalculated to include the displacement that could be attributed to the 6-acetylmorphine derived from heroin degradation during the incubation, all of the apparent heroin binding was accounted for by the 6-acetylmorphine. These results are consistent with previous reports of the low binding affinity of morphine congeners (e.g., codeine) that lack a free phenolic 3-hydroxyl group and support the view that heroin is a prodrug which serves to determine the distribution of its intrinsically active metabolites, 6-acetylmorphine and morphine.

Animals↗
PubMed1983

Structural correlates of cellular tumorigenicity and anchorage independence in transformed fibroblasts.

The ability on nonhematopoietic cells to proliferate in vitro without attachment to a solid surface (anchorage independence) is known to be highly correlated with their ability to form tumors in nude mice. Transformed cells in vitro frequently also show less organization of the intracellular actin-containing microfilament bundles and less cell-surface fibronectin compared to normal cells. We have examined whether the loss of the anchorage requirement for growth is related to either of these structural changes in the cellular cytoskeleton. Our approach was to select a series of subclones from a nontransformed Syrian hamster fibroblast line, NIL8, for the acquisition of either anchorage independence in vitro or tumorigenicity in nude mice. These subclones were then examined for concomitant changes in the cytoskeletal structures. We found that anchorage independence, decreased actin cable organization, and tumorigenicity in nude mice were coordinately induced in both the in vitro- and in vivo-selected subclones, whereas the loss of fibronectin was not consistently coinduced with these three markers. These results suggest that the transformation-associated decrease in actin cable organization in this type of cell enhances the ability to grow without anchorage in vitro and to form tumors in vivo.

Actins↗
PubMed1983

Tumor formation by SV40-transformed human cells in nude mice: the role of SV40 T antigens.

Human cells transformed in vitro by SV40 rarely form tumors in nude mice. We examined whether these cells as a group are inherently nontumorigenic or whether they are potentially tumorigenic but rejected by the athymic host, possibly by nonspecific immune mechanisms. SV80 and NG8 are SV40-transformed human cell lines that express all of the transformed properties, including anchorage-independent growth, but do not form tumors in adult nude mice after injection of as many as 10(8) cells. Both the SV80 and NG8 cell lines have SV40-specific transplantation antigens which crossreact with those present on SV40-transformed (but tumorigenic) rodent cells. We found that SV80 cells, though not NG8 cells, induced progressively growing lethal tumors if the cells are injected repeatedly into neonatal nude mice. Somatic cell hybrids between SV80 or NG8 cells and a highly tumorigenic cell line derived from a human tumor continue to express the virus-induced antigens and fail to form tumors in adult nude mice. These results strongly suggest that at least for some SV40-transformed human cells, the failure to form tumors in nude mice may be due to their expression of virus-induced transplantation antigens rather than the absence of tumorigenic potential.

Animals↗
PubMed1983

Structurally restricted conjugates of the beta-subunit of the human chorionic gonadotropin to produce antisera.

Structurally restricted conjugates, beta-hCG(-NH2)4(-NHC-NH-NH2)11(-C-O-TT)1-11, were synthesized by protecting the amino and guanidino functional groups of the beta-subunit of the human chorionic gonadotropin (beta-hCG) with t-Boc groups; then, the carboxyl groups of the protected intermediate were coupled by carbodiimide reagents with basic groups of tetanus toxoid (TT). After removal of the t-Boc groups, the immunogen has a total of fifteen amino and guanidino functional groups, which may be superior to carboxyl groups, for immunologic recognition. Conjugates, prepared in non-polar and aqueous systems, had ratios of beta-hCG to TT of 13:1 and 7:1, respectively. Immunization of rabbits yielded antisera which showed an inhibition of 50% for 41-62 ng/ml, beta-hCG, at final dilution ratios of up to 1:80,000.

Animals↗