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Biomedical subjects

S Han

Publications and source records attributed to S Han.

At least 271 records · Page 15Linked to original sources
PubMed1993

[Analysis of estrogen receptors in normal bone and bone tumor tissues].

Thirteen human normal bone and fifteen bone tumor tissues were assayed for estrogen receptor (ER) by Dextran-coated Charcoal method (Scatchard plot). The results showed that the concentrations of ER in normal bone tissues (15.12 +/- 14.68 fmol/mg pro) were higher than that of bone malignant tumors (8.04 +/- 6.71 fmol/mg pro) P < 0.05). The binding dissociation constants (Kd) of ER in bone tumors (18.46 +/- 27.10 x 10(-11) mol/L) was lower than those in normal ones (39.91 +/- 20.13 x 10(-11) mol/L) (P < 0.025). The percentages for positive score of ER in normal and tumor ones (23.1%, 26.7%) were not significantly different (P > 0.05). Our study indicated that the variations of concentration and affinity of ER in bone related to the tumor incidence. That cytosol ER content was decreased in malignant bone tumors whereas that of affinity increase suggests an impairment or change of an intact receptor mechanism in this tissues.

Adolescent↗
PubMed1993

[Anti-implantation action of nylestriol and its effect on uterine cytosol estrogen and progesterone receptor in rabbits].

The anti-implantation action of nylestriol in rabbit was studied. The changes of uterine cytosol estrogen and progesterone receptor (ER and PR) were analysed with the dextran-coated charcoal method. Plasma progesterone level of early pregnant rabbits was measured by radioimmunoassay. The results showed that oral nylestriol could obviously prevent the early pregnancy of rabbit by anti-implantation of blastocyst. The content of ER decreased in the nylestriol group (P < 0.01). The content of PR in nylestriol group was lower than that of the control group (P < 0.05). No significant difference of plasma progesterone level was noted between the control and treatment groups. These results suggest that there is close relationship between the anti-implantation effect of nylestriol and the decreased content of cytosol ER and PR during the pre-implantation period.

Animals↗
PubMed1993

Genomic organization, chromosomal localization and developmental expression of hepatocyte growth factor-like protein.

Hepatocyte growth factor is a multi-functional protein that elicits different biological responses in a tissue- or cell-specific manner. We have isolated the cDNA and gene for a previously unidentified protein that has the identical domain composition as hepatocyte growth factor. We have called this novel protein "hepatocyte growth factor-like protein". Both proteins contain four kringle domains followed by a serine protease-like domain. Overall, the two proteins are only about 50% identical. The human gene for hepatocyte growth factor-like protein has been localized to locus p21 on chromosome 3, where one or more tumor suppressor genes may be located. Although the biological function of HGF-like protein has not been determined we have localized the major site of synthesis to the liver. Whether this newly identified member of the hepatocyte growth factor family of proteins is involved in the development and differentiation of the liver remains to be determined.

Amino Acid Sequence↗
PubMed1992

Specific identification of collagens and their fragments by clostridial and anti-collagenase antibody.

A method specific for identification of collagens irrespective of type, species, or tissue origin, and of their derived fragments of molecular weight more than 10,000, is described. The method is based on the low-temperature affinity between clostridial collagenase and almost all types of collagens as well as on the affinity between collagenase and its antibodies. Various collagens or fragments derived from them by treatment with CNBr were separated by SDS-PAGE and immobilized onto a nitrocellulose membrane by a slot-blot technique or electrotransfer. Following binding of clostridial collagenase to a collagen or its fragments at 0 degrees C, the collagen-collagenase complex was fixed with glutaraldehyde. The complex was then allowed to bind anti-collagenase antibody at room temperature. The new complex was subsequently treated with 125I-labeled donkey anti-rabbit IgG and visualized as an autoradiogram. Under the conditions of low temperature used, the collagenase binds to collagens without causing their digestion. This procedure is specific for detection of soluble collagens as well as of insoluble collagens converted to fragments by treatment with CNBr. The method is uniquely suited for detection of fragments of tissue collagens. Also, it may serve as a prototype for methods for detection of other specific polymeric substances.

Amino Acid Sequence↗
PubMed1992

[Characteristics of monoclonal antibodies against chorionic gonadotropin receptor].

We reported the production of monoclonal antibodies (McAb) against chorionic gonadotropin (CG) receptor by fusing spleen cells of BALB/c mice immunized with purified pseudomonas maltophilia CG receptor with mouse myeloma line (SP 2/0). Four hybridoma cell lines secreting CG receptor McAbs were obtained (ED 490, DG 390, AB 890, GE 590). GE 590 is IgG 1; ED 490, DG 390, AB 890 are IgG2b. I125-HCG and ED 490, DG 390. AB 890 recognized CG receptor different antigenic determinant. Increased concentrations of GE 590 were in inverse proportion to the amount of I125-HCG binding to human ovarian tissues showing that normal ovarian tissues and ovarian malignant tumors have different HCG receptor antigenic determinant. This study indicated that these McAbs may be useful in studying the structure of CG receptor and in providing a valuable evidence for early diagnosis and treatment of ovarian malignant tumors.

Adenocarcinoma, Mucinous↗
PubMed1992

[Study of the estrogen receptor and progesterone receptor in human cervical carcinoma].

Three hundred and twelve different cervical specimens have been tested for estrogen (ER) and progesterone receptor (PR) content with dextran-coated charcoal method (DCC). The results showed that the concentrations of ER and PR in normal cervical tissues were higher than those in malignant cervical tissues, and that the percentage of positive scores for ER and PR in cervical squamous epithelial tissues were higher than that in malignant cervical tissues. That the variances of ER and PR in cervical malignant tumors were not parallel suggested that the production or/and the mechanism of receptor action might be impaired. The percentage of positive scores for ER was not correlated with the clinical stages whereas that of PR was inversely proportional to clinical stages. That some patient with cervical cancer had high level of PR and had both ER and PR positive implied the possibility for endocrine therapy. The content and distribution of ER and PR in normal cervical tissues are consistent with the effects of sex hormone.

Carcinoma, Squamous Cell↗
PubMed1992

Nude mouse interim host model for human parathyroid grafts. II. Alteration of MHC antigens in human PTG grafts in the nude mouse.

Human parathyroid (PTG) tissues from cadaver (C-PTG), 5-month fetus (F-PTG) and PTG adenoma (A-PTG) were transplanted into the kidney subcapsular areas of Balb/C nude mice as interim host. Dynamic changes in the amount of tissue major histocompatibility complex (MHC) antigen present within the transplantation period were observed. The results showed that during 100 days of interim hosting, no obvious changes in the expression of tissue MHC class I antigens were seen, but the expression of tissue MHC class II antigens was significantly reduced. The changes of MHC antigens in different donor human PTG tissues were compared.

Adenoma↗
PubMed1991

Characterization of the DNF15S2 locus on human chromosome 3: identification of a gene coding for four kringle domains with homology to hepatocyte growth factor.

A human genomic DNA library was screened by using conditions of reduced stringency with a bovine cDNA probe coding for the kringle domains in prothrombin in order to isolate the human prothrombin gene. Twelve positives were identified, three of which coded for prothrombin (Degen & Davie, 1987). Phage L5 was characterized in more detail because of its strong hybridization to the cDNA probe and its unique restriction map compared to the gene coding for human prothrombin. The gene in L5 was sequenced and found to code for a kringle-containing protein. A human liver cDNA library was screened by using a genomic probe from the gene in L5. cDNAs were isolated that contained sequence identical with regions in the gene in L5. Comparison of the cDNA with the gene indicated that the gene in L5 was composed of 18 exons separated by 17 intervening sequences and is 4690 bp in length. Exons ranged in size from 36 to 242 bp in length while intervening sequences ranged from 77 to 697 bp in length. The putative protein encoded by the gene in L5 contains four kringle domains followed by a serine protease-like domain. This domain structure is identical with that found in hepatocyte growth factor (HGF), although the two proteins are only about 50% identical. On the basis of the similarity of the protein encoded by L5 and HGF, we propose that the putative L5 protein be tentatively called HGF-like protein until a function is identified. The DNA sequence of the gene and cDNA and its translated amino acid sequence were compared against GenBank and NBRF databases. Sequences homologous to DNF15S1 and DNF15S2, human DNF15S2 lung mRNA, and rat acyl-peptide hydrolase were identified in exon 17 to the 3' end of the characterized sequence for the gene. From our results, it is apparent that the gene coding for human HGF-like protein is located at the DNF15S2 locus on human chromosome 3 (3p21). The gene for acyl-peptide hydrolase is 444 bp downstream of the gene coding for HGF-like protein, but on the complementary strand. The DNF15S2 locus has been proposed to code for one or more tumor suppressor genes since this locus is deleted in DNA from small cell lung carcinoma, other lung cancers, renal cell carcinoma, and von Hippel-Lindau syndrome.

Amino Acid Sequence↗
PubMed1991

Characterization of the mouse cDNA and gene coding for a hepatocyte growth factor-like protein: expression during development.

The cDNA and gene coding for mouse hepatocyte growth factor-like protein (HGF-like protein) were isolated and characterized. The size of the gene from the site of initiation of transcription to the polyadenylation site is 4613 bp in length and is composed of 18 exons separated by 17 intervening sequences. The exons range in size from 36 to 227 bp in length, while the intervening sequences range in size from 78 to 613 bp in length. The site of initiation of transcription was identified by primer extension analysis using total RNA isolated from mouse liver. On the basis of these results, the first exon is 146 bp in length and includes 94 bp of 5'-noncoding sequence. The sequence 5'TATGTG3' is present between 34 and 39 bp upstream of the transcription start site and could potentially be the TATA sequence found for many constitutively expressed eukaryotic genes to be the promoter for RNA polymerase II. The sequence 5'GCAAT3' at -96 to -92 may be the CCAAT sequence responsible for stimulation of transcription of some eukaryotic genes. The same sequences in the Genbank and NBRF databases were homologous to similar regions in the genes coding for both human and mouse HGF-like protein (Han et al., 1991). The acyl-peptide hydrolase gene is 410 bp downstream of the mouse HGF-like protein, but is transcribed from the complementary strand. The mouse cDNA for HGF-like protein codes for a putative protein with the same domain structure as its human homologue with four kringle domains followed by a serine protease-like domain. On the basis of the translated sequence of the cDNA, the mouse HGF-like protein would be 716 amino acids in length with a molecular weight of 80K. There are four potential N-linked carbohydrate attachment sites. The DNA and amino acid sequences of mouse HGF-like protein are compared to the human protein. Overall, the two proteins are about 80% identical with each other. In contrast to mRNA for human HGF-like protein, which is 2.4 and 3.0 kilobases in length in human liver, only the smaller species is seen in mouse and rat liver. The expression pattern of mRNA coding for HGF-like protein during development and in maternal rats was determined by Northern analysis. It is apparent that the majority of mRNA coding for HGF-like protein is expressed in liver. Messenger RNA is also expressed at a lower level in lung, adrenal, and placenta.

Amino Acid Sequence↗
PubMed1991

Initial experience with a practical hyperfractionated accelerated radiotherapy regimen.

This paper presents early results of a trial of a three-fractions-per-day (TID) regimen that is more convenient to schedule than the Continuous Hyperfractionated Accelerated Radiotherapy (CHART) protocol currently being tested in Europe. The treatment schedule used in the CHART regimen has been modified from 36 fractions of 1.5 Gy TID in 12 days to 72 fractions of 1.1 Gy in 24 treatment days, with all fractions delivered during normal working hours. With no weekend treatments, the entire course of radiotherapy is completed in less than 5 weeks. The doses used were determined using the L-Q model, with correction for incomplete repair between fractions and for accelerated repopulation of cancer cells. Comparison with historical controls shows statistically significant improvements both in CR rates for the primary tumor and in acute toxicity, as measured by reduced treatment interruptions. L-Q model calculations predict that, compared to the highest dose achieved in previous studies without exceeding tolerance, we are able to obtain a 12% increase in bioeffect dose to the primary tumor due to accelerating the treatment. An analysis of the potential tumoricidal effectiveness of this new treatment regimen shows that it should be better than several other accelerated fractionation schedules being tested for all values of Tpot. For short Tpot times, the advantage may be as much as one log cell kill, corresponding to a 10-15% potential improvement in local control.

Aged↗
PubMed1991

[Preparation of monoclonal antibodies against chorionic gonadotropin receptor and study of its characteristics].

We reported the production of monoclonal antibodies (McAbs) against chorionic gonadotropin hormone (CG) receptor by fusing spleen cells of BALB/c mice which had been immunized by purified bacteria (Pseudomonas maltophilia) CG receptor with mouse myeloma line SP2/0. Four hybridoma cell lines secreting CG receptor McAbs were obtained (ED490 DG390, AB890 and GE590). The titers of specific antibodies of both mice ascites and culture supernatant were 10(-2)-10(-6) and 1-10(-2) respectively, by solid phase ELISA. Double-Immunodiffusion test showed that the McAb GE590 was IgG1, and the McAbs ED490, DG390 and AB890 were IgG2b Immunoprecipitation indicated that 125I-HCG could bind the HCG receptor which had reacted with McAbs ED490, AB890 and DG390, suggesting that they may recognize the receptor with different antigenic determinant. Interaction of McAb GE590 with the receptor showed that the increased concentration of GE590 was in inverse proportion to the amount of 125I-HCG binding receptor, indicating that both the McAb and 125I-HCG could recognize a common site of receptor and that increased concentration of McAb GE590 may induce some change in conformation and structure of the receptor. Our study suggested that these McAbs may be used for studying structure of CG receptor.

Animals↗
PubMed1990

Ferryl and hydroxy intermediates in the reaction of oxygen with reduced cytochrome c oxidase.

Cytochrome c oxidase catalyses the 4-electron reduction of dioxygen to water and translocates protons vectorially across the inner mitochondrial membrane. Proposed reaction pathways for the catalytic cycle of the O2 reduction are difficult to verify without knowing the structures of the intermediates, but we now have such information for the catalytic intermediates in the first steps of the reaction of O2 with cytochrome c oxidase from resonance Raman spectroscopy, a technique that enables iron-ligand stretching modes to be identified. Here we report on two more key intermediates: a ferryl-oxo (Fe4 = O2-) and a ferric-hydroxy (Fe3+--OH-) intermediate at the level of 3- and 4-electron reduction, respectively. We identified these intermediates by their characteristic iron-oxygen stretching frequencies (786 cm-1 for Fe4+ = O2-, and 450 cm-1 for Fe3+ -- OH-) and oxygen and deuterium isotope shifts. The oxo atom in the ferryl intermediate is hydrogen-bonded and the iron-oxygen bond in the hydroxy intermediate is anomalously weak. With the identification of the primary, ferryl and hydroxy intermediates, the predominant structures at almost all stages of O2 reduction are now known and the catalytic pathway can be described with more certainty.

Deuterium↗
PubMed1990

Primary intermediate in the reaction of mixed-valence cytochrome c oxidase with oxygen.

The reaction of dioxygen with mixed-valence cytochrome c oxidase was followed in a rapid-mixing continuous-flow apparatus. The optical absorption difference spectrum and a kinetic analysis confirm the presence of the primary oxygen intermediate in the 0-100-microseconds time window. The resonance Raman spectrum of the iron-dioxygen stretching mode (568 cm-1) supplies evidence that the degree of electron transfer from the iron atom to the dioxygen is similar to that in oxy complexes of other heme proteins. Thus, the Fe-O2 bond does not display any unique structural features that could account for the rapid reduction of dioxygen to water. Furthermore, the frequency of the iron-dioxygen stretching mode is the same as that of the primary intermediate in the fully reduced enzyme, indicating that the oxidation state of cytochrome a plays no role in controlling the initial properties of the oxygen binding site.

Chemical Phenomena↗
PubMed1990

Metastable intermediates in myoglobin at low pH.

Resonance Raman and optical absorption spectra of ligand-free (deoxy) myoglobin and CO-bound myoglobin (MbCO) at pH 2.6 have been measured by using continuous-flow/rapid-mixing techniques. The spectra of deoxy myoglobin at low pH within 6 ms of the pH drop demonstrate that the iron-histidine bond has been ruptured but that the heme is still five-coordinate. Comparison with data from model complexes indicates that a weak-field ligand, such as a water molecule, is coordinated at the fifth position. The Raman spectrum of MbCO at low pH has an Fe-CO stretching mode that is characteristic of a six-coordinate heme with an unhindered Fe-CO moiety. Immediately following the pH drop in this case, there is no indication that the iron-proximal histidine bond is broken. Three different structural changes are detected at low pH: (i) the iron-proximal histidine (F8) bond in ligand-free myoglobin is broken and replaced by a weak-field ligand, (ii) the distal pocket in MbCO is opened, and (iii) protein constraints on the heme group in MbCO are relaxed. Previous conclusions that the kinetics of CO-binding in hemoproteins at low pH is modified by rupturing the iron-proximal histidine bond are supported by these new results which, however, demand a more complete reevaluation of the phenomenon.

Animals↗