Biomedical subjects

Y Y Li

Publications and source records attributed to Y Y Li.

At least 91 records · Page 5Linked to original sources

PubMed1994

Association of Helicobacter pylori with gastric cancer and observations on the detection of this bacterium in gastric cancer cases.

OBJECTIVE: The aim of the present study was to assess the prevalence of Helicobacter pylori infection in Chinese patients with advanced gastric cancer, to compare this with a matched control population, and to identify factors that may effect the detection of H. pylori in patients with gastric cancer. METHODS: Fifty-one patients with advanced gastric cancer and 102 age/sex-matched controls were included in the study. For the detection of H. pylori, both biopsy specimens and sera were collected from the patients, whereas only sera were collected from the controls. A strong association was shown between H. pylori and both intestinal and diffuse type gastric cancer. Antibiotic intake in the month before endoscopic examination, the site of collection of biopsy specimens, and tumor size were identified as factors that may reduce the histological detection of H. pylori in gastric cancer patients. CONCLUSIONS: These data provide supporting evidence of an association between H. pylori infection and gastric cancer and indicate that, in certain circumstances, histological evaluation of H. pylori infection in gastric cancer cases may be less reliable than serological evaluation.

Adult↗

PubMed1994

[Mitochondrial DNA mutations in patients with myocardial diseases].

Amplification of one of the frequently deleted regions of myocardial and lymphocytic mitochondrial DNA (mt DNA) from patients with dilated cardiomyopathy (DCM), acute myocardial infarction (AMI) and normal controls was carried out with polymerase chain reaction (PCR). The results showed that multiple deletions exist in mtDNA of both patients and normal controls. 7.8 kb deletion was detected in myocardial mtDNA of 2 patients with AMI and 10 patients with DCM; 7.47, 8.10, 8.32 and 8.48kb deletions were found in lymphocytic mtDNA of 3 patients with AMI and 25 patients with DCM as well as 14 normal controls. The incidence and abundance of the 7.47kb mtDNA deletion increased with age of all the subjects studied. Quantitative analysis showed that mutated mtDNA accumulated up to 10% of total mtDNA-only in some older patients. Single strand conformational polymorphism analysis of the amplified 8,530-9,333 fragment allowed us to find a point mutation in a patient with DCM. Clinical significance of the mutations in mtDNA was discussed.

Adolescent↗

PubMed1994

[The effect of iron deficiency anemia on the auditory brainstem response in infant].

Our study attempts to explore the mechanism by which iron deficiency anemia (IDA) affects the brain function of infants. We made auditory brainstem response (ABR) test for 48 IDA infants and 30 normal control infants, aged 6-36 months and reexamined ABR in 4 IDA infants after three months iron therapy. 26 cases of abnormal ABR among 48 IDA infants were found, it took 54.2% of total IDA infants. IDA led mainly to peripheral impairments of auditory system and rarely to brainstem. There was a direct relationship between the severity of IDA and the degree of abnormality of the ABR in infants. The threshold of ABR in IDA infants was significantly higher than that of in control group. It suggests that IDA infants have listening comprehensive difficulty as a result of impairment in high frequency hearing. After follow-up of 4 IDA infants, it was found that the impairment of auditory system could be reversible after prompt correcting of IDA. This observation has important significance for child health in the future.

Anemia, Hypochromic↗

PubMed1993

Disruption of mitotic spindle orientation in a yeast dynein mutant.

Dynein motor isoforms have been implicated as potential kinetochore-associated motors that power chromosome-to-pole movements during mitosis. The recent identification and sequence determination of genes encoding dynein isoforms has now permitted the in vivo analysis of dynein function in mitosis. In this report we describe the identification and mutational analysis of the gene, DHC1, encoding a dynein heavy chain isoform in Saccharomyces cerevisiae. Sequence analysis of a 9-kb genomic fragment of the DHC1 gene predicts a polypeptide highly homologous to dynein sequences characterized from sea urchin, Dictyostelium, Drosophila, and rat. Mutations in the yeast dynein gene disrupt the normal movement of the spindle into budding daughter cells but have no apparent effect on spindle assembly, spindle elongation, or chromosome segregation. Our results suggest that, in yeast, a dynein microtubule motor protein has a nonessential role in spindle assembly and chromosome movement but is involved in establishing the proper spindle orientation during cell division.

Amino Acid Sequence↗

PubMed1993

Effects of GAL10-SUC2 promoter combinations on SUC2 gene expression in S. cerevisiae.

The plasmid series YEP51 delta n bearing GAL10-SUC2 promoter combinations were constructed by inserting SUC2 gene with different upstream deletions downstream GAL10 promoter on YEP51. After transforming yeast cells S. cerevisiae, the invertases expressed by each of the transformants were measured and analysed by means of PAGE. The results showed that: 1) The SUC2 gene with upstream deletion to at -636bp expressed high level glycosylated form of invertase under glucose derepression, while SUC2 gene with more extensive deletions to -223 bp or more lost its response to glucose derepression; 2) Each part of GAL10-SUC2 promoter combination acted almost independently. All of the combinations showed no apparent coordinated promoter function under our experimental conditions; 3) Sequences between -89bp and -41bp of SUC2 upstream region are responsible for constitutive expression of nonglycosylated invertase. The two tracts of poly (dA-dT) of this region may serve as promoter elements.

DNA Transposable Elements↗

PubMed1993

Analysis of 155 patients with chemical injury: a 5-year experience.

From July 1986 to June 1991, 155 patients were treated in our department for various chemical burn injuries. The experience over the 5-year period is reviewed. Among these patients, 109 patients were between 20 and 40 years of age and accounted for 70.3 per cent of all chemical burn patients. It is suggested that chemical burns are very common in people of working age. Chemical burn manifestations were unlike those of thermal injury. The scene of injury, type of chemical agent, age of patients, clinical manifestation and management of the burn surface are discussed. Although the patients were given the same physical therapy, early tangential or full thickness excision and immediate autografting yielded better results than conservative treatment and shortened hospital stay.

Adolescent↗

PubMed1993

Improbability of harmful autoimmune responses resulting from immunization with HIV-1 envelope glycoproteins.

Autoimmunity mediated by cross-reactive antibodies, elicited by HIV-1 envelope glycoproteins gp120/gp160, has been postulated to contribute to the pathogenesis of AIDS. Partial amino acid sequence homology between gp120/gp160 and several human host proteins, including MHC antigens and immunoglobulins, has been perceived as the basis for immunological cross-reactivity. Binding of antibodies from sera of HIV-1-infected individuals to selected host proteins and/or to synthetic peptides derived from them and the inhibitory activity of such sera in assays measuring the functional activity of T cells provided apparent support for the autoimmunity hypothesis, which is also relevant to the issue of safety of anti-HIV-1 vaccines. Considering the possibility that the detected autoantibodies may arise for reasons other than antibody responses to gp120/gp160, the immunological cross-reactivity between gp120/gp160 and the relevant host proteins was investigated using hyperimmune rabbit anti-gp120/gp160 and monoclonal antibodies. As determined from dilution end-point comparisons for polyclonal anti-gp120, the cross-reactivity of anti-gp120 with CD4 was undetectable (< 10(-5)%). The cross-reactivity of anti-gp120/gp160 with HLA-I and HLA-II antigens was also undetectable (< 4 x 10(-4)%) and that with other human proteins reported to have partial sequence homology with gp120/gp41 was < or = 0.013%. Anti-gp120/gp160 did not have detectable inhibitory effects in functional assays measuring proliferative T cell responses. Therefore, immunization with gp120/gp160 is unlikely to elicit harmful autoimmune responses.

Amino Acid Sequence↗

PubMed1993

[Studies on the genetic susceptibility to dilated cardiomyopathy].

HLA-DQB1,-DRB1 genes of 27 Chinese patients with dilated cardiomyopathy (DCM), 7 high risk individuals in a DCM kindred and 17 normal control subjects were analysed with the use of restriction fragment length polymorphisms (RFLP) with full length DQB1 and DRB1 cDNA probes according to the standard and nomenclature of the Xth International Histocompatibility Workshop. The resulting restriction patterns allowed genotyping of HLA-DR and HLA-DQw. D-DQw8 frequency increased significantly in patients with DCM as compared with that of the controls (P < 0.05). D-DQw4 also increased in patients although no statistical significance was shown when Chi-square value was corrected with Yate's correction, whereas D-DQw5 overrepresented in controls (P < 0.05). Over half of the high risk individuals (4/7) in the familial DCM kindred carry D-DQw8 and D-DQw4. These results support the hypothesis that HLA class II genes were associated with an increased risk for DCM, HLA-DQB rather than -DRB may confer genetic susceptibility to DCM.

Adult↗

PubMed1993

[Clinical significance of changes in plasma renin-angiotensin aldosterone system in patients with high altitude pulmonary edema].

Plasma levels of renin activity, angiotensin II and aldosterone were determined in 16 patients with high altitude pulmonary edema (HAPE) with radioimmunoassay and compared with those in the controls including 9 patients with high altitude acute response (HAAR) and 14 health subjects. All of them arrived recently in Lhasa, a place with an altitude of 3,658 m. The results showed that the concentration of plasma renin activity, angiotensin II, and aldosterone was significantly increased (P < 0.05-0.001) in patients with HAPE and higher than that in the controls. It is suggested that the increase plays a role in the development of pulmonary edema in patients with HAPE.

Adolescent↗

PubMed1993

[Ectopic expression and the significance of HLA-class II antigens in the myocardium in patients with dilated cardiomyopathy].

Expression of HLA-class II antigens (DQ, DP) in the myocardium of patients with different heart diseases and normal controls was studied with indirect immunofluorescence (IIF). The positive rates in different groups were as follows: dilated cardiomyopathy (DCM, 12/13,+- ), rheumatic heart disease (2/4, +-+ + +), congenital heart diseases (1/14,+), left atrial myxoma (0/1) and normal controls (1/8,+). The immunofluorescent area was in the endocardium and endothelial cells of the blood vessels (VIII factor related antigen positive areas in dual staining of the myocardium). There were significant differences between the positive rates of DCM and those of other heart diseases including rheumatic heart disease, congenital heart diseases and left atrial myxoma (chi 2 cor = 15.3, P < 0.001), as well as between DCM and normal controls (chi 2 cor = 9.9, P < 0.01). The expression of HLA-class II antigens is highly selective. Ectopic expression has been postulated to be responsible for autoimmune diseases. So it can be used as a specific marker for autoimmunity in DCM.

Adult↗

PubMed1993

A stable vector for high-level expression and secretion of human interferon alpha A in yeast.

Yeast high stable plasmid vector pHC11 was constructed by introducing pEM-BL Yi27 cleaved with SmaI into the SnaBI site of intact 2 microns plasmid. The result of plasmid stability assay revealed that 82% of the host cells still harbored the vector after 50-generations growth in non-selective medium, which confirmed the existence of a non-functional region in 2 microns plasmid. The human interferon alpha A (IFN alpha A) gene expression-secretion cassette was inserted into pHC11, and the yeast transformant was cultured in complex medium. The data showed that the expressed product was 36.8% of the total protein amount in the culture supernatant and the IFN alpha A biological activity was 2.6 x 10(10) units per liter, demonstrating that high-level expression and secretion of IFN alpha A were achieved in yeast by using the stable vector pHC11.

Escherichia coli↗

PubMed1992

Cells transfected with human interleukin 6 cDNA acquire binding sites for the hepatitis B virus envelope protein.

Earlier studies revealed that human interleukin 6 (IL-6) contains recognition sites for the hepatitis B virus (HBV) envelope (env) protein, and that IL-6 and anti-IL-6 antibodies, respectively, inhibited the interaction of cells expressing a receptor for HBV with the preS(21-47) segment of the HBV env protein, encompassing the complementary attachment site for IL-6. This suggested that IL-6 mediates HBV-cell interactions. We report that: (a) Chinese hamster ovary cells transfected with human IL-6 cDNA and Spodoptera frugiperda ovarian insect cells infected with recombinant baculovirus carrying human IL-6 cDNA expressed receptors for the preS(21-47) region of the HBV env protein, indicating that expression of IL-6 on the surface of cells is sufficient to endow them with receptors for HBV. (b) Among peptides covering the entire sequence of human IL-6 and the corresponding antipeptide antibodies, the peptide IL-6[35-66] and anti-IL-6[35-66] most effectively inhibited the interaction between human hepatoma HepG2 cells and the preS(21-47) ligand, suggesting that this region of the human IL-6 sequence encompasses a binding site for the HBV env protein. (c) Studies with replacement set peptides from the preS(21-47) sequence indicated that residues 21-25, 28, 31, 33-35, 39, and 43-45 can be replaced by alanine (serine) residues, while all the other residues are essential for maintaining the cell receptor/IL-6 binding activity. Further delineation of complementary sites on IL-6 and on the HBV env protein may contribute to the design of compounds inhibiting HBV replication.

Amino Acid Sequence↗

PubMed1992

Basement membrane and its components on lymphocyte adhesion, migration, and proliferation.

During inflammation and recirculation, lymphocytes migrate into tissues by traversing the capillary endothelium, a process known as extravasation. After crossing the endothelial cells, lymphocytes come into contact with the basement membrane, which is a specialized layer of extracellular matrix containing predominantly laminin, collagen type IV, entactin, and heparan sulfate proteoglycans. In tissue invasion by inflammatory cells and metastatic tumor cells, the basement membrane serves as a substratum for cell adhesion and migration. However, the role of basement membrane in lymphocyte extravasation remains unclear. In this study, we investigated the effect of basement membrane on lymphocyte adhesion, migration, and proliferation, using matrigel as a model for basement membrane. We observed that matrigel promotes both lymphocyte adhesion and migration, with entactin primarily responsible for promoting adhesion and laminin for promoting migration. In addition, activation of lymphocytes by anti-CD3 enhances their adhesion and migration on matrigel-coated substratum. We also observed that matrigel inhibits the proliferation of lymphocytes stimulated by Con A. Furthermore, we demonstrated that laminin is the matrigel component responsible for inhibiting lymphocyte proliferation. However, matrigel has no effect on the proliferation of lymphocytes stimulated by LPS. These results suggest that matrigel has different effects on lymphocyte subpopulations. In agreement with the results on proliferation, matrigel also inhibits the production of IL-2 by Con A-stimulated lymphocytes.

Animals↗

PubMed1992

LEU2 gene homolog in Kluyveromyces lactis.

A DNA fragment that can complement the leu2 mutation of Saccharomyces cerevisiae was cloned from the genomic library of Kluyveromyces lactis. The nucleotide sequence revealed an open reading frame of 362 codons, 75% homologous to S. cerevisiae LEU2 gene. The upstream region contained a CCGGAACCGG sequence identical to the site of leucine-specific control of LEU2. Further upstream, there is a partial open reading frame homologous to rat ribosomal protein L7.

Amino Acid Sequence↗

PubMed1992

Altered cytokine production in black patients with keloids.

The treatment of keloids in black patients remains a medical dilemma. Previous studies have focused on primary alterations in the metabolism of fibroblasts as the key in the etiology of this condition. Yet alterations in the production of various cytokines which may alter fibroblast responses secondarily have received little attention. Twelve black patients with clinical and histological diagnosis of keloids and eight black control volunteers were studied. Peripheral blood mononuclear-cell (PBMC) fractions from both groups were assayed for production of interleukin-1 (IL-1), interleukin-2 (IL-2), interleukin-6 (IL-6), alpha-interferon (IFN-alpha), beta-interferon (IFN-beta), gamma-interferon (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), and tumor necrosis factor-beta (TNF-beta). The production of IFN-alpha, IFN-gamma, and TNF-beta were markedly depressed in keloid patients compared to normal controls. However, IL-1 and IL-2 production was not significantly different between the two groups. In contradistinction, keloid patients produce greater amounts of IL-6, TNF-alpha, and IFN-beta. Altered levels of immunoregulatory cytokines may play a significant role in the net increase in collagen which characterizes keloid formation.

Black People↗

PubMed1992

Differential inhibition of human basal keratinocyte growth to silver sulfadiazine and mafenide acetate.

The impact of topical antimicrobial agents on improving the survival of patients with major thermal injuries is significant. However, the effects of these agents on cells responsible for wound healing has only recently received attention. Fresh human basal keratinocytes were grown in serum-free modified MCDB 153 medium under standard tissue culture conditions. Cells were subsequently exposed to concentrations of silver sulfadiazine and mafenide acetate as low as 1/100 of that used clinically over a period of 5-7 days. Cellular responses documented with hemocytometer cells counts, cellular protein assays, phase-contrast microscopy, and transmission electron microscopy show only severe toxicity to mafenide acetate. Such data imply that inhibition of wound epithelialization is greater with the use of mafenide acetate than with the use of silver sulfadiazine.

Cell Count↗

PubMed1992

Changes in serum osmolality and osmolar discrepancy in burned patients.

Forty-three patients with burns of various depth and burn surface area were studied to determine the relationship between burn severity and changes of serum osmolality. The results showed that the osmolality in four patients who died were significantly higher than the osmolalities of survivors with very serious burns, whose osmolalities decreased gradually to normal level. Hyperosmolality and obvious osmolar discrepancy often co-exist. It is suggested that the changes of osmolality and osmolar discrepancy can reflect the burn severity and prognosis of the patients.

Adolescent↗

PubMed1992

Epidemiology of Helicobacter pylori in southern China: identification of early childhood as the critical period for acquisition.

A large cross-sectional study to investigate the prevalence and possible modes of transmission of Helicobacter pylori was done in southern China. Serum samples (1727) were collected from Guangzhou city and three rural areas of Guangdong Province, and the prevalence of H. pylori infection was determined using an ELISA. Each subject completed a questionnaire. The overall prevalence of H. pylori infection was 44.2%; a significantly higher prevalence was found in Guangzhou (52.4%) than in the rural areas (38.6%). This difference was generally reflected in the group 0-5 years old, but the rate of increase in seroprevalence for H. pylori over 5 years of age was similar (1%/year). This study provides important new data on the acquisition of H. pylori, particularly in the early years of life, and shows that density of living conditions is a prime determinant in the acquisition of H. pylori.

Adolescent↗