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Biomedical subjects

D He

Publications and source records attributed to D He.

At least 73 records · Page 4Linked to original sources
PubMed1996

Structure and dynamic organization of centromeres/prekinetochores in the nucleus of mammalian cells.

Although considerable research has been focused on understanding the structure and molecular organization of the centromere-kinetochore complex of mitotic chromosomes, few reports have dealt with the centromere (prekinetochore) in the interphase nucleus. In the present study, we utilized anti-centromere antibodies from the serum of patients with the autoimmune disease, scleroderma CREST (calcinosis, Raynaud's phenomenon, esophageal dismotility, sclerodactyly, telangiectasia), as probes to investigate the structure and morphogenesis of the centromere in interphase nuclei of three cell lines using laser scanning confocal microscopy and immunoelectron microscopy. Of particular interest were the chromosomes of the Indian muntjac (2n = 6 in females and 2n = 7 in males), whose large centromeres are thought to have evolved through the tandem fusion of smaller centromeres of a Chinese muntjac-like progenitor species (2n = 46). The various forms and patterns of centromeres observed in the nucleus correlated with stages in the cell cycle as determined by bromodeoxyuridine labeling and apparently represent stages in prereplication, replication and maturation. Immunoelectron microscopic studies using CREST antisera indicated that the high order structure of chromatin associated with each prekinetochore undergoes a regular unfolding-refolding cycle, displaying small bead-like subunits tandemly arranged along a linear thread of centromeric DNA, much like that reported for mitotic chromosomes. Individual centromeres/prekinetochores form a stable association with the 9-13 nm core filaments of the nucleoskeletal network in the nucleus that later become the chromosome scaffold of mitotic chromosomes. Our findings provide morphological support for the hypothesis that the spatial arrangements of individual centromeres within the nucleus may have influenced centromeric translocations and fusions during chromosome evolution. Therefore, the centromere-kinetochore complex, best known for its essential role in partitioning chromosomes in mitosis and meiosis, may also function in chromosome movements and associations in interphase.

Animals↗
PubMed1996

[Regulatory effect of lingqi anshen liquor on erythrocyte immune function and antioxidation in immunosuppressed mice].

The regulatory effect of Lingqi Anshen Liquor (LQASL) on erythrocyte immune function and antioxidation in cyclophosphamide induced immunosuppressed model mice was observed. After given LQASL for 7 days, the results showed that it could antagonize the inhibitory action of cyclophosphamide significantly, demonstrated by raising the level of superoxide dismutase activity, erythrocyte immune adhesive enhance factor and erythrocyte C3b receptor rosette forming rate, lowering the serum malondialdehyde, erythrocyte adhesive inhibitory factor and erythrocyte immunocomplex rosette forming rate. It suggested that LQASL can regulate the erythrocyte immune function and antagonize the injury of oxygen free radical in immunosuppressed mice.

Animals↗
PubMed1996

[Human papillomavirus infection and esophageal squamous cell carcinoma].

Human papillomavirus (HPV) infection, especially high risk types HPV 16 and 18, have been studied widely in cervical cancer. However, HPV infection in esophageal cancer has not been well defined. In the present study, immunohistochemistry, PCR and Southern blot hybridization methods were used to detect HPV infection in 127 cases of esophageal squamous cell carcinoma. Immunohistochemistry results indicated that the virus was detected frequently in well differentiated carcinoma. The positive rates for BPV and HPV E6 protein were 60.6% (77/127) and 43% (54/127) respectively. Meanwhile, PCR and Southern hybridization showed that 35.9% (37/103) of esophageal squamous cell carcinomas have HPV DNA, which included 20.4% (21/103) HPV 16 and 7.8% (8/103) HPV 18. Of the 103 cases, only 1 had both HPV 16 and HPV 18 DNA. Our results suggest that HPV infection is present in esophageal squamous cell carcinoma and may play a role in its pathogenesis.

Adult↗
PubMed1996

[Furosemide test for diagnosis of endolymphatic hydrops: a clinical exploration].

Furosemide test (FT) is a clinical method for the diagnosis of endolymphatic hydrops (EH). Immediately preceding i.v. injection of 20 mg furosemide, a caloric test was performed with 50 micromilligrams of water at 30 degrees C. Nystagmography was employed to measure the maximum slow velocity of caloric nystagmus. The test was repeated one hour after the injection. The two sets of data were then compared. An increase beyond 22.97% was defined as positive. The first group was composed of 54 patients of EH as the experimental group, and the second group 54 patients with vertigo of non-EH as control. The positive rates of the two groups were 70.4% and 25.9% respectively. It showed that FT was useful for detecting EH. The percentage of directional preponderance (DP) was obviously descended in the two groups after i.v. furosemide. Descending rate was 77.8% (21/27) in the first group, which had reached the normal value in 9 cases. It was showed that DP was important also for criticizing FT. The hearing of all subjects was not damaged. When the renal function of the subject was normal and not combined with the use of aminoglycoside antibiotics, the dose of FT was not dangerous to the hearing and had few side reactions. The mechanism of dehydration in hydropic labyrinth was presumed to be acute systemic diuresis, but the effect in inner ear was unknown.

Diagnosis, Differential↗
PubMed1995

The C terminus of mitosin is essential for its nuclear localization, centromere/kinetochore targeting, and dimerization.

Mitosin is a novel 350-kDa nuclear phosphoprotein that dramatically relocates from the evenly nuclear distribution in S phase to the centromere/kinetochore and mitotic apparatus in M phase. The dynamic relocalization of mitosin is accompanied by the phosphorylation of itself, suggesting that mitosin plays a role in mitotic progression. The molecular basis of nuclear localization and targeting of mitosin to the centromere/kinetochore were characterized using a set of epitope-tagged deletion mutants. The data indicate that the extreme C terminus (amino acids 2,487-3,113) of mitosin has both an independent centromere/kinetochore targeting domain and an unusually spaced bipartite nuclear localization signal. Moreover, the same centromere/kinetochore targeting domain was shown to be essential for the ability of mitosin to bind to itself or other putative mitosin-associated proteins through use of the yeast two-hybrid system. These results suggest that the C terminus of the mitosin is essential for its role in influencing cell cycle progression.

Amino Acid Sequence↗
PubMed1995

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Journal Article↗
PubMed1995

Nuclear matrix proteins as structural and functional components of the mitotic apparatus.

The eukaryotic nucleus is a membrane-enclosed compartment containing the genome and associated organelles supported by a complex matrix of nonhistone proteins. Identified as the nuclear matrix, this component maintains spatial order and provides the structural framework needed for DNA replication, RNA synthesis and processing, nuclear transport, and steroid hormone action. During mitosis, the nucleoskeleton and associated chromatin is efficiently dismantled, packaged, partitioned, and subsequently reassembled into daughter nuclei. The dramatic dissolution of the nucleus is accompanied by the assembly of a mitotic apparatus required to facilitate the complex events associated with nuclear division. Until recently, little was known about the fate or disposition of nuclear matrix proteins during mitosis. The availability of specific molecular probes and imaging techniques, including confocal microscopy and improved immunoelectron microscopy using resinless sections and related procedures, has enabled investigators to identify and map the distribution of nuclear matrix proteins throughout the cell cycle. This chapter will review the structure, function, and distribution of the protein NuMA (nuclear matrix mitotic apparatus) and other nuclear matrix proteins that depart the nucleus during the interphase/mitosis transition to become structural and functional components within specific domains of the mitotic apparatus.

Animals↗
PubMed1995

The effect of porphyrin and radiation on ferrochelatase and 5-aminolevulinic acid synthase in epidermal cells.

The effects of ultraviolet A (UVA) and blue light on ferrochelatase protein, and its mRNA level, in 5-aminolevulinic acid (ALA)-loaded A431 cells was evaluated. Western blot analysis of ferrochelatase protein showed a protein band of 43 kDa. There was a decrease in the protein concentration 24 h and 48 h after irradiation of these cells. In contrast, as judged by Northern blot analysis, there was no change in ferrochelatase mRNA level. Measurement of ALA synthase activity showed an ALA dose-dependent but radiation-independent decrease of enzyme activity, suggesting an end-product feedback inhibition. Since reactive oxygen species generated by porphyrin-induced photochemical reaction may be involved in the decrease in ferrochelatase protein, the effect of scavengers of reactive oxygen species was evaluated by measuring porphyrin accumulation in irradiated, ALA-loaded A431 cells. Porphyrin accumulation was significantly decreased in the presence of singlet oxygen scavenger sodium azide (0.05 mM, 40.6% suppression) or hydroxyl radical scavenger mannitol (5.0 mM, 45.0% suppression). These data suggest that the photochemical reaction induced by porphyrin and irradiation resulted in a decrease in ferrochelatase protein content, but had no effect on ferrochelatase mRNA level nor on ALA synthase activity. The decrease in protein was partly mediated by the reactive oxygen species.

5-Aminolevulinate Synthetase↗
PubMed1995

Muscle fibre type and dimension in genetically obese and lean Zucker rats.

Skeletal muscle structure and morphology may be altered in obesity. To study this further, muscles from six genetically obese (fa/fa) and six normal male rats were examined at 15 weeks of age. The gluteus medius, vastus lateralis and rectus abdominis muscles were dissected out and stained for histochemical fibre typing. In addition the fibre cross-sectional area was measured on a graphic tablet. The proportion of fast-twitch fibres was larger in the vastus lateralis and rectus abdominis muscles of the obese rats (P < 0.01); no difference was seen for the gluteus medius muscle. For the normal rats the cross-sectional area of the fast-twitch fibres was 2-3 times larger than the area of slow-twitch fibres in the same muscle. The cross-sectional area of the fast-twitch fibres in the obese rats was 40-47% less than in the control animals (P < 0.003), while no difference between the two groups was found for the slow-twitch fibre area. The data thus suggest that in the genetically obese rats the development of fast-twitch fibres was primarily affected. Moreover, in these animals some muscles may be more affected than others.

Animals↗
PubMed1995

The effect of ALA and radiation on porphyrin/heme biosynthesis in endothelial cells.

To study porphyrin biosynthesis in human microvascular endothelial cells, HMEC-1 cells, a transformed human microvascular endothelial cell line, were incubated with 5-aminolevulinic acid (ALA), the precursor of endogenous porphyrins, and porphyrin accumulation was measured spectro-fluorometrically. The HMEC-1 cells accumulated porphyrin in a concentration-related and a time-dependent fashion. Protoporphyrin was the predominant porphyrin accumulated in the cells. The effect of light on protoporphyrin accumulation was evaluated by exposing the ALA-loaded HMEC-1 cells to ultraviolet-A (UVA) and blue light, followed by another incubation with ALA for 2-24 h. Enhancement of protoporphyrin accumulation in irradiated HMEC-1 cells was observed 2-24 h after irradiation, which was associated with a decrease in ferrochelatase protein and activity. Porphyrin accumulation from ALA after irradiation was significantly decreased when catalase (750-3000 U/mL, 29.3-44.3% suppression) or superoxide dismutase (270 U/mL, 36.4% suppression) was present during irradiation. These data demonstrate that HMEC-1 cells were capable of porphyrin biosynthesis, and that exposure of protoporphyrin-containing HMEC-1 cells to UVA and blue light, which includes the Soret band spectrum, decreased the ferrochelatase activity and its protein. These changes were mediated, at least in part, by reactive oxygen species.

Aminolevulinic Acid↗