Search PubMed⌕ Search

Biomedical subjects

Y Y Lu

Publications and source records attributed to Y Y Lu.

36 records · Page 2Linked to original sources
PubMed1993

Homozygous deletions within 9p21-p22 identify a small critical region of chromosomal loss in human malignant mesotheliomas.

Previous DNA analyses have demonstrated that 9p13-p22 is a frequent site of chromosomal loss in leukemia, glioma, melanoma, and lung and bladder carcinomas. Recent cytogenetic studies have revealed recurrent alterations of 9p in malignant mesothelioma (MM). We have performed gene dosage studies of 23 MM cell lines, using probes for several 9p21-p22 loci (IFNB, IFNA/IFNW, D9S3, D9S126, D9S169, and D9S171), to identify a common region of deletion. Homozygous and/or hemizygous deletions were identified in 19 (83%) cell lines. Homozygous losses (10 cell lines; 43%) occurred most often at the D9S171 and IFNA/IFNW loci. In 8 cell lines, 2 or more of the 9p loci examined were found to be homozygously lost; 2 others displayed homozygous losses only at the D9S171 locus. Results from our deletion mapping analysis suggest that D9S171 is located between IFNA/IFNW and D9S126. The data presented here indicate that allelic loss from 9p21-p22 is a common occurrence in MM and further delineate the location of a putative 9p tumor suppressor gene(s) to a region between IFNA/IFNW and D9S171. These MM cell lines may facilitate efforts to define an even smaller critically deleted region, leading to the eventual cloning and characterization of this gene.

Base Sequence↗
PubMed1991

Tumorigenicity, metastasis and suppression of MHC class-I expression in murine fibroblasts transformed by mutant v-ras deficient in GTP binding.

We have introduced point mutations in v-rasH to study their effects on biochemical and biological properties of the ras-encoded protein p21. Several of these mutant proteins do not bind GTP and thus lack GTPase activity, while others were shown to have their GTP binding reduced. We have introduced these ras mutants into NIH 3T3 fibroblastoid cells to study major parameters of clinical importance which are associated with neoplastic transformation, particularly MHC expression in cells, metastasis and tumorigenesis in both nude mice and immune competent mice. Our data show that certain mutations in v-ras differentially affect the expression of the transformed phenotype. Mutant ras molecules deficient in GTP binding fail to generate rapidly progressing tumors in immune competent mice, and not all morphologically transformed cells were capable of experimental metastasis. Cells transformed by certain v-ras mutants form tumors in immunocompetent mice and show reduced expression of MHC class-I antigens. Other cells are morphologically transformed and tumorigenic in athymic nude mice, but fail to form tumors in normal mice and show levels of MHC class-I antigen expression similar to non-transformed 3T3 cells. The inverse relationship between MHC class-I-antigen expression and the degree of transformation in fibroblastoid cells suggests that the ras gene product could be involved in regulating MHC expression.

Animals↗
PubMed1991

[Studies on the classification of thermophilic actinomycetes. IV. Determination of thermophilic Streptomyces hygroscopicus group].

The thermophilic streptomyces hygroscopicus is one of the pathogens of farmer's lung disease. The identified 60 strains of thermophilic streptomyces hygroscopicus coming from the isolates from the haystack, moldy hay and sputa collected from Jiangsu, Hubei province and Shanghai in China. These strains are grown around 50 degrees C and have moist patches on the surface of colonies. It is proved that protease can be extracted from cultured H9-4 strain. This protease is provided with antigen, the farmer's lung disease of rabbit can be induced in animals experiments. On clinical diagnosis the farmer's lung disease can be detected by sera test. From the identification of the 60 thermophilic streptomyces hygroscopicus strains, we found the morphological cultural, physiological characteristics and cell wall composition of H9-4 and T562 well different from description hitherto. So two of them are identified as new species. H9-4 is named as Streptomyces thermoendus sp. nov. and T562 is named as Streptomyces thermobicorno-hygroscopicus sp. nov.

Animals↗
PubMed1990

trans-Dominant suppressor mutations of the H-ras oncogene.

Site-directed mutagenesis of the conserved sequence motifs of p21 generated a group of mutant p21s defective in GTP binding. Some of these mutants were highly transforming, whereas others were transformation defective. Among the latter group, we found two mutants, derived from the v-H-ras oncogene by substituting the asparagine-116 with tyrosine and isoleucine, that exhibited a trans-dominant activity of suppressing the transformed phenotype of NIH3T3 cells induced by a long terminal repeat-linked c-H-ras and a wild-type v-H-ras. They caused reduction of the colony-forming efficiency in soft agar (78% in c-ras-transformed cells; 55% in v-ras cells) and morphological reversion of ras transformants. Subclones of revertants expressed a great excess of mutant p21 relative to the c-ras p21 present in these cells. These mutants were not lethal to NIH3T3 cells. Apparently, defective proteins encoded by suppressor mutants sequestered vital targets for ras function. Suppressor mutants also induced morphological reversion of NIH3T3 cells transformed by src, fes/flp, sis, and fms oncogenes, suggesting that these oncogenes function upstream to ras in the signaling pathways. Cells transformed by mos and a chemical carcinogen were unaffected.

Animals↗
PubMed1989

Rapid method for identifying subclones bridging gaps between contiguous DNA sequences.

Randomly sequencing of a limited number of unidirectional deletion subclones efficiently generated contiguous DNA sequences with some gaps between them. Gap-bridging subclones were identified by agarose gel electrophoresis. Those located at either end of each individual contiguous sequence were used as standard marker molecules; the subclones between them proved to be correctly identified in most cases. A 4064 bp DNA fragment containing the psr gene was sequenced with the strategy described in this paper.

Base Sequence↗
PubMed1989

[Diagnosis of iron deficiency anemia with an optimum combination of tests].

Basing on the analysis of five tests including serum ferritin, erythrocyte protoporphyrin, serum iron, total iron binding capacity and transferrin saturation in 92 anemic patients who were classified into iron deficient anemia (IDA) and non-iron deficient anemia by their bone marrow iron status, three models of combination of tests were designed by varying the test combination and diagnostic levels in model 1 and 2 and multiple regression analysis in model 3. The sensitivity and specificity for IDA were 93.7% and 93.1% respectively with the optimum scheme of combination of tests from model 2 in which serum ferritin has more weight than other tests. With the optimum scheme from the model 3 which was the discriminant function, the sensitivity and specificity were 93.3% and 100% respectively when the scheme tests the cases who are not included in the calculation of the function. It will decrease the number of false-positive or false-negative diagnosis due to the complex results of combination of test when the optimum combination of tests is used in the investigation of iron status and clinical work.

Anemia, Hypochromic↗
PubMed1987

Activated c-Ha-ras oncogene with a guanine to thymine transversion at the twelfth codon in a human stomach cancer cell line.

The rat fibroblast cell line Rat 1 was transfected with total DNA of a gastrocarcinoma cell line, BGC-823. The transforming gene was cloned from the genomic library of the secondary transformants using in situ hybridization with a probe of the human Alu repeat sequence. This cloned gene is homologous to the protooncogene c-Ha-ras. The activation lesion of the transforming gene was identified by sequence analysis as a single nucleotide substitution of thymine for guanine in the 12th codon. This results in the substitution of valine for glycine at the 12th amino acid of the Mr 21,000 protein.

Adenocarcinoma↗
PubMed1987

Structural significance of the GTP-binding domain of ras p21 studied by site-directed mutagenesis.

Point mutations of p21 proteins were constructed by oligonucleotide-directed mutagenesis of the v-rasH oncogene, which substituted amino acid residues within the nucleotide-binding consensus sequence, GXG GXGK. When the glycine residue at position 10, 13, or 15 was substituted with valine, the viral rasH product p21 lost its GTP-binding and autokinase activities. Other substitutions at position 33, 51, or 59 did not impair its binding activity. G418-resistant NIH 3T3 cell lines were derived by transfection with constructs obtained by inserting the mutant proviral DNA into the pSV2neo plasmid. Clones with a valine mutation at position 13 or 15 were incapable of transforming cells, while all other mutants with GTP-binding activity were competent. A mutant with a substitution of valine for glycine at position 10 which had lost its ability to bind GTP and its autokinase activity was fully capable of transforming NIH 3T3 cells. These cells grew in soft agar and rapidly formed tumors in nude mice. The p21 of cell lines derived from tumor explants still lacked the autokinase activity. These findings suggest that the glycine-rich consensus sequence is important in controlling p21 activities and that certain mutations may confer to p21 its active conformation without participation of ligand binding.

Animals↗
PubMed1980

Restriction endonucleases from three strains of Haemophilus influenzae.

The restriction endonucleases, Hin P1 I1), Hin S1 I and Hin S2 I are isolated from three strains of Haemophilus influenzae respectively. By polymin P treatment, ammonium sulphate, precipitation and column chromatography on phosphocellulose and on heparin-Sepharose Hin P1 I is partially purified. No contaminating deoxyribonuclease activities have been detected in this purified enzyme preparation. The fact that the digestion patterns of Hin P2 I and Hha I on phage lambda, plasmids ColE1 an pBR 322 DNAs are identical that they are isoschizomers but theri splitting sites are different. The banding patterns of Hin S1 I and Hin S2 I are also the same as that of Hha I.

DNA Restriction Enzymes↗