Biomedical subjects

X Gong

Publications and source records attributed to X Gong.

At least 73 records · Page 4Linked to original sources

PubMed1998

[Clinical diagnosis of Colles fracture combined with dorsal subluxation of radial carpal joints].

OBJECTIVE: To study the criteria for evaluating Colles fracture combined with dorsal radiocarpal subluxation (DRS). METHOD: Fifty cases of Colles fracture combined with DRS, 100 cases of simple Colles fracture without DRS, and 100 normal wrist joint controls were included. We analysed central point displacement and perpendicular line ratio on the lateral view X-ray. For comminuted and severely displaced fracture, central point displacement (CPD) was not adopted because of difficulties in identifying the central point of the articular surface. Perpendicular line ratio (PLR) was suggested. RESULT: Prominent difference was seen in the CPDs and the PLRs between the Colles fracture combined with DRS group and the simple Colles fracture and the normal control group (P < 0.01). Prominent relevance between the CPD and the PLR was also found (P < 0.05). CONCLUSION: Central point displacement and perpendicular line ratio can be regarded as the diagnostic criteria for Colles fracture combined with DRS. PLR is especially valuable when the central point is hard to be identified in very comminuted and severely displaced fractures. DRS is suggested when CPD is more than 2.5 mm and PLR is less than 0.76.

Adolescent↗

PubMed1998

[Effect of keratinocyte growth factor on corneal epithelial wound healing].

OBJECTIVE: To select effective methods for accelerating corneal epithelial wound healing and treating persistent corneal epithelial defect. METHODS: Exogenous keratinocyte growth factor (KGF, 0.1 ng/ml - 100 ng/ml) was added to cultures of human corneal epithelial cells and DNA synthesis in corneal epithelial cells was measured with [(3)H]-thymidine incorporation and liquid scintillation techniques. The effective concentration of topical application of KGF was calculated and 1 microg/ml KGF was then applied topically to rabbit eyes. Corneal epithelial defect was measured by a digital computer at different times. RESULTS: KGF at a dosage ranging from 1 ng/ml to 100 ng/ml enhanced cellular proliferation effectively (the rate of cell proliferation 27.66% - 76.73%) and in a dose-dependent manner (r = 0.9233, P < 0.001). Topical application of KGF significantly accelerated corneal wound healing in rabbits (Epithelial healing rate in the KGF-treated group was 1.77 +/- 0.23 mm(2)/h, while in the PBS-treated group it was 1.49 +/- 0.24 mm(2)/h; P < 0.05). CONCLUSION: The results suggest that exogenous KGF stimulate proliferation of human corneal epithelial cells and accelerate corneal epithelial wound healing in vivo.

Animals↗

PubMed1998

[Immunohistochemical studies on wholemounts of the cornea and iris-ciliary body after corneal transplantation].

OBJECTIVE: To study the phenotype of the cells involved in the pathogenesis of allograft rejection after corneal transplantation. METHODS: Wholemounts of the cornea and iris-ciliary body were isolated and prepared from normal rats and those after penetrating corneal transplantation. Immunohistochemical stainings were carried out on these wholemounts using monoclonal antibodies to CD3 (T cell), CD4 [T-helper (Th) cell], CD8 [T-suppressor (Ts) cell], macrophages, dendritic cells, B lymphocytes, major histocompatibility complex (MHC) class II antigen and transforming growth factor-beta (TGF-beta). RESULTS: All the cells mentioned above except B lymphocytes were positive and present in a small number in the peripheral cornea and limbus of normal rats. A massive influx of CD3, CD4, CD8 positive cells, macrophages, dendritic cells, MHC class II and TGF-beta positive cells not only into cornea but also into the iris was observed 7 days after allograft corneal transplantation. Whereas no B cell was found in the allograft. Such a cellular response was not found in the rats in which corneal transplantation with autologous cornea was performed. CONCLUSION: T cells, Th cells, Ts cells, macrophages, dendritic cells, MHC class II positive cells and TGF-beta positive cells are involved in the pathogenesis of corneal allograft transplantation. The involvement of the iris and ciliary body may promote or aggravate the allograft rejection.

Animals↗

PubMed1998

[An ideal imaging quality can be obtained from the evenly scattering x-ray density].

Since X-ray image quality was evaluated by the self-delivering function, the limitations in the application of fixative focus X-ray tube seem more outstanding. How to improve the quality of the x-ray image has been one of the focus problems in the field of the x-ray diagnosis. If we use the x-ray tube of the evenly scattering x-ray density as the radio source, we can get the ideal images.

Radiography↗

PubMed1998

[A methodological study of frequency domain analysis on heart rate variability and RT interval variability].

Recently, heart rate variability (HRV) as a non-invasive measure for assessing the balance of autonomic nervous system has drawn more attentions and HRV analysis has become a focus of the ECG signal processing. QT interval represents the ventricular repolarization duration. QTV might reflect the balance of autonomic nervous system in other way. QTV analysis might complement HRV analysis. Because of the difficulty in detecting QT interval, RT interval is often used instead of QT interval. HRV and QTV detecting methods have been presented in this paper. After recording 24 h ECG signals, R fiducial marks are detected correctly and ectopic beats are removed. T peaks are detected on the basis of templet matching and correlation. The analysis in frequency domain consists of 24 h 3-dimensional frequency chart, as well as trends of HF/LF and HF, with fast Fourier transform and autoregressive techniques. We acquired ECG signals from subjects under controlled respiration in different frequencies. The results of HRV and RTV spectral analysis have shown that HF peak is modulated at the frequency of controlled respiration, which proves that HF peak is dependent on the vagal activity and our method is correct. The establishment of these methods has provided a basis for further research, and the development of HRV and QTV analysis techniques will be more helpful for early diagnosis, monitoring and prognostic assessment of some diseases.

Algorithms↗

PubMed1998

A study of clinical characteristics and treatment of Mooren's ulcer.

OBJECTIVE: To investigate the clinical characteristics and to compare the effects of several therapies of Mooren's corneal ulcer. METHODS: 550 consecutive cases of Mooren's corneal ulcer inpatients were analysed, including the age, sex, laterality of the eye, ulcer location, perforative rate, cure rate of surgeries, recurrent rate, and the effects of conjunctiva excision, lamellar keratoplasty (LKP), LKP and plus cyclosporin A eye drop. RESULTS: The average age of onset of the corneal ulcer was 48.4 years old, the ratio of the male to the female patients was 1:0.74, the bilateral disease was 30% of the total cases, 31.5% of the bilateral disease occurred in the younger group, and 68.5% of the bilateral ulcer occurred in the older group, ulcers located at the limbus of the palpebral fissure were 70% of the total cases, perforative rate was 13.3%, 43.2% of the perforation occurred in the younger group, and 56.8% of the perforation occurred in the older group, recurrent rate of the post-operation was 25.6%, the cure rate of the first procedure of LKP and plus cyclosporin A eye drop was 73.7%, the final cure rate was 95.6%, and the preservative rate of the corneal anatomical structure of the surgeries was 99.7%. CONCLUSION: The study primarily provided the clinical characteristics of Mooren's corneal ulcer patients of China. The available data do not support the present concept of the classification of the two clinical types. The bilateral ulcer may be the malignant type of Mooren's ulcer. LKP and plus cyclosporin A eye drop was an effective treatment of Mooren's corneal ulcer.

Adolescent↗

PubMed1998

Cytotoxicity of contact lens care solution to human corneal epithelium in vitro.

PURPOSE: To investigate the cytotoxicity of soft contact lens multi-purpose care solutions which are now in common use in China. METHODS: The cell culture method was used. Cytotoxicity was indicated by significant increases in the number of dead cells relative to controls. RESULTS: Cells were exposed to soft contact lens care solutions for 15 min. They were irregular in shape and variable in size. The intercellular space increased and variable in size. The intercellular space increased and the cells became scrunken. With the time of exposure elongated, damage of cells became more severe. CONCLUSIONS: Four kinds of soft contact lens multi-purpose care solutions may have harmful effects on the culture of human corneal epithelial cells. Soaked lenses should be rinsed with saline before being placed in the eyes in order to reduce the potential toxicity of contact lens care solutions.

Cell Count↗

PubMed1998

In vivo radioprotective effects of angiogenic growth factors on the small bowel of C3H mice.

This study was undertaken to determine if acidic or basic fibroblast growth factor (FGF1 or FGF2) or vascular endothelial growth factor (VEGF) alters the radiation response of small bowel after total-body irradiation (TBI). Female C3H mice were treated with various doses of angiogenic growth factor administered intravenously 24 h before or 1 h after TBI. Radiation doses ranged from 7 to 18 Gy. End points measured were the number of crypts in three portions of the small bowel, the frequency of apoptosis of crypt cells at various times after TBI, and the LD50/30 (bone marrow syndrome) and LD50/6 (GI syndrome). Fibroblast growth factors alone, without TBI, decreased the number of crypts per circumference significantly. Among the factors tested, FGF2 caused the greatest decline in baseline crypt number. Despite this decrease in the baseline crypt number, after irradiation the number of surviving crypts was greater in animals treated with growth factor. The greatest radioprotection occurred at intermediate doses of growth factor (6 to 18 pg/mouse). Mice treated with FGF1 and FGF2 had crypt survival curves with a slope that was more shallow than that for saline-treated animals, indicating radiation resistance of crypt stem cells in FGF-treated mice. The LD50/6 was increased by approximately 10% for all treatments with angiogenic growth factors, whether given before or after TBI. Apoptosis of crypt cells was maximum at 4 to 8 h after TBI. The cumulative apoptosis was decreased significantly in animals treated with angiogenic growth factors, and the greatest protection against apoptosis was seen in animals treated with FGF2 prior to TBI. All three angiogenic growth factors tested were radioprotective in small bowel whether given 24 h before or 1 h after irradiation. The mechanism of protection is unlikely to involve proliferation of crypt stem cells, but probably does involve prevention of radiation-induced apoptosis or enhanced repair of DNA damage of crypt cells.

Angiogenesis Inducing Agents↗

PubMed1997

Antioxidant enzyme activities in lens, liver and kidney of calorie restricted Emory mice.

Dietary calorie restriction extends both mean and maximum life span and retards age-related diseases, including eye lens cataract in Emory mice. The beneficial effects of calorie restriction have been hypothesized to reflect enhanced tissue antioxidant capacity. As a test of this hypothesis, we reared male and female Emory mice on control (C) or 40% calorie-restricted (R) diets. We then determined activities of total superoxide dismutase (T-SOD), Cu/Zn-SOD, Mn-SOD, glutathione peroxidase (GPx), glutathione reductase (GR) and catalase (CAT) in eye lens, liver and kidney of young (4.5 or 6 months), mature (11 or 12 months) and old (22 months) animals. Effects of diet, age and sex were evaluated by multi-factor ANOVA. Only kidney GR activities (mean +/- S.E.M.) were significantly enhanced with the R diet (R, 61 +/- 2 vs. C, 54 +/- 3 U/mg protein; P = 0.03). More frequently, we noted reduced antioxidant enzyme activity in R as compared with C animals, including reduced activities of T-SOD in lens, liver and kidney, Cu/Zn-SOD in liver and kidney, liver Mn-SOD and liver CAT (P < 0.05). Effects of age on antioxidant enzyme activity in C mice included age-dependent decreases in lens and kidney CAT and in liver Mn-SOD. There was also an age-dependent increases in liver and kidney Cu/Zn-SOD and liver GR. None of these age-dependent alterations in antioxidant enzyme function were attenuated in tissues of mice fed the R diet. Values for liver CAT were significantly lower in females than in males (P = 0.05). These results indicate that antioxidant enzyme activities in Emory mouse tissues are influenced by diet, age and sex. However, it is unlikely that increased lifespan and attenuation of cataract (and perhaps other age-dependent debilities), which are associated with the R diet in the Emory mouse, are due to enhanced antioxidant enzyme capabilities.

Age Factors↗

PubMed1997

Disruption of alpha3 connexin gene leads to proteolysis and cataractogenesis in mice.

Gap junction channels formed by alpha3 (Cx46) and alpha8 (Cx50) connexin provide pathways for communication between the fiber cells in the normal transparent lens. To determine the specific role of alpha3 connexin in vivo, the alpha3 connexin gene was disrupted in mice. Although the absence of alpha3 connexin had no obvious influence on the early stages of lens formation and the differentiation of lens fibers, mice homozygous for the disrupted alpha3 gene developed nuclear cataracts that were associated with the proteolysis of crystallins. This study establishes the importance of gap junctions in maintaining normal lens transparency by providing a cell-cell signaling pathway or structural component for the proper organization of lens membrane and cytoplasmic proteins.

Aging↗

PubMed1997

Regulation of ubiquitin-conjugating enzymes by glutathione following oxidative stress.

Upon oxidative stress cells show an increase in the oxidized glutathione (GSSG) to reduced glutathione (GSH) ratio with a concomitant decrease in activity of the ubiquitinylation pathway. Because most of the enzymes involved in the attachment of ubiquitin to substrate proteins contain active site sulfhydryls that might be covalently modified (thiolated) upon enhancement of GSSG levels (glutathiolation), it appeared plausible that glutathiolation might alter ubiquitinylation rates upon cellular oxidative stress. This hypothesis was explored using intact retina and retinal pigment epithelial (RPE) cell models. Exposure of intact bovine retina and RPE cells to H2O2 (0.1-1.7 micromol/mg) resulted in a dose-dependent increase in the GSSG:GSH ratio and coincident dose-dependent reductions in the levels of endogenous ubiquitin-activating enzyme (E1)-ubiquitin thiol esters and endogenous protein-ubiquitin conjugates and in the ability to form de novo retinal protein-125I-labeled ubiquitin conjugates. Oxidant-induced decrements in ubiquitin conjugates were associated with 60-80% reductions in E1 and ubiquitin-conjugating enzyme (E2) activities as measured by formation of ubiquitin thiol esters. When GSH levels in RPE cells recovered to preoxidation levels following H2O2 removal, endogenous E1 activity and protein-ubiquitin conjugates were restored. Evidence that S thiolation of E1 and E2 enzymes is the biochemical link between cellular redox state and E1/E2 activities includes: (i) 5-fold increases in levels of immunoprecipitable, dithiothreitol-labile 35S-E1 adducts in metabolically labeled, H2O2-treated, RPE cells; (ii) diminished formation of E1- and E2-125I-labeled ubiquitin thiol esters, oligomerization of E225K, and coincident reductions in protein-125I-labeled ubiquitin conjugates in supernatants from nonstressed retinas upon addition of levels of GSSG equivalent to levels measured in oxidatively stressed retinas; and (iii) partial restoration of E1 and E2 activities and levels of protein-125I-labeled ubiquitin conjugates in supernatants from H2O2-treated retinas when GSSG:GSH ratios were restored to preoxidation levels by the addition of physiological levels of GSH. These data suggest that the cellular redox status modulates protein ubiquitinylation via reversible S thiolation of E1 and E2 enzymes, presumably by glutathione.

Animals↗

PubMed1997

Activity of ubiquitin-dependent pathway in response to oxidative stress. Ubiquitin-activating enzyme is transiently up-regulated.

Relations between the ubiquitin pathway and cellular stress have been noted, but data regarding responses of the ubiquitin pathway to oxidative stress are scanty. This paper documents the response of this pathway to oxidative stress in lens cells. A brief exposure of lens epithelial cells to physiologically relevant levels of H2O2 induces a transient increase in activity of the ubiquitin-dependent pathway. Ubiquitin conjugation activity was maximal and increased 3. 5-9.2-fold over the activity noted in untreated cells by 4 h after removal of H2O2. By 24 h after removal of H2O2, ubiquitin conjugation activity returned to the level noted in untreated cells. In parallel to the changes in ubiquitin conjugation activity, the activity of ubiquitin-activating enzyme (E1), as determined by thiol ester formation, increased 2-6.7-fold during recovery from oxidation. Addition of exogenous E1 resulted in an increase in ubiquitin conjugation activity and in the levels of ubiquitin carrier protein (E2)-ubiquitin thiol esters in both the untreated cells and the H2O2-treated cells. These data suggest that E1 is the rate-limiting enzyme in the ubiquitin conjugation process and that the increases in ubiquitin conjugation activity which are induced upon recovery from oxidation are primarily due to increased E1 activity. The oxidation- and recovery-induced up-regulation of E1 activity is primarily due to post-synthetic events. Substrate availability and up-regulation of E2 activities also appear to be related to the enhancement in ubiquitinylation upon recovery from oxidative stress. The oxidation-induced increases in ubiquitin conjugation activity were associated with an increase in intracellular proteolysis, suggesting that the transient increase in ubiquitinylation noted upon recovery from oxidative stress may play a role in removal of damaged proteins from the cells.

Adenosine Triphosphate↗

PubMed1997

Monocyte chemotactic protein-2 (MCP-2) uses CCR1 and CCR2B as its functional receptors.

Monocyte chemotactic protein (MCP)-2 is a member of the C-C chemokine subfamily, which shares more than 60% sequence homology with MCP-1 and MCP-3 and about 30% homology with macrophage inflammatory protein (MIP)-1alpha, regulated on activation of normal T cell expressed (RANTES), and MIP-1beta. Despite this considerable sequence homology to other C-C chemokines, MCP-2 appears to have unique functional properties in comparison with other C-C chemokines such as MCP-1 and MCP-3. Although evidence obtained from studies on leukocytes suggested that MCP-2 may share the receptors with these C-C chemokines, the actual functional receptors for MCP-2 have not yet been identified. In this study, by using radioiodinated MCP-2, we identified high affinity binding sites for MCP-2 on human peripheral blood monocytes. The MCP-2 binding was competed for by MCP-1 and MCP-3, but less well by MIP-1alpha or RANTES. In experiments using cells transfected with C-C chemokine receptors, 125I-MCP-2 bound to human embryonic kidney 293 cells transfected with CCR1 or CCR2B, known to also bind MIP-1alpha/RANTES and MCP-1, respectively, but both shared by MCP-3. The binding of 125I-MCP-2 to these receptor-transfected cells was displaced completely by chemokines that bind to these receptors. Both CCR1- and CCR2B-transfected 293 cells showed significant migration in response to MCP-2, in addition to responding to other specific chemokines. These results clearly demonstrate that MCP-2, unlike MCP-1, uses both CCR1 as well as CCR2B as its functional receptors, and this accounts for the unique activities of MCP-2.

Binding Sites↗

PubMed1997

Developmental regulation of Zbu1, a DNA-binding member of the SWI2/SNF2 family.

The SWI2/SNF2 gene family has been implicated in a wide variety of processes, involving regulation of DNA structure and chromatin configuration, mitotic chromosome segregation, and DNA repair. Here we report the characterization of the Zbu1 gene, also known as HIP116, located on human chromosome band 3q25, which encodes a DNA-binding member of this superfamily. Zbu1 was isolated in this study by its affinity for a site in the myosin light chain 1/3 enhancer. The protein has single-stranded DNA-dependent ATPase activity, includes seven helicase motifs, and a RING finger motif that is shared exclusively by the RAD5, spRAD8, and RAD16 family members. During mouse embryogenesis, Zbu1 transcripts are detected relatively late in fetal development and increase in neonatal stages, whereas the protein accumulates asynchronously in heart, skeletal muscle, and brain. In adult human tissues, alternatively spliced Zbu1 transcripts are ubiquitous with highest expression in these tissues. Gene expression is also dramatically induced in human tumor lines and in Li-Fraumeni fibroblast cultures, suggesting that it is aberrantly regulated in malignant cells. The developmental profile of Zbu1 gene expression and the association of the protein with a tissue-specific transcriptional regulatory element distinguish it from other members of the SWI2/SNF2 family and suggest novel roles for the Zbu1 gene product.

Adenosine Triphosphatases↗

PubMed1997

Identification of previously unrecognized common elements in eukaryotic promoters. A ribosomal RNA gene initiator element for RNA polymerase I.

A new ribosomal RNA promoter element with a functional role similar to the RNA polymerase II initiator (Inr) was identified. This sequence, which we dub the ribosomal Inr (rInr) is unusually conserved, even in normally divergent RNA polymerase I promoters. It functions in the recruitment of the fundamental, TATA-binding protein (TBP)-containing transcription factor, TIF-IB. All upstream elements of the exceptionally strong Acanthamoeba castellanii ribosomal RNA core promoter, to within 6 base pairs of the transcription initiation site (tis), can be deleted without loss of specific transcription initiation. Thus, the A. castellanii promoter can function in a manner similar to RNA polymerase II TATA-less promoters. Sequence-specific photo-cross-linking localizes a 96-kDa subunit of TIF-IB and the second largest RNA polymerase I subunit (A133) to the rInr sequence. A185 also photo-cross-links when polymerase is stalled at +7.

Acanthamoeba↗

PubMed1997

Age-related decline in ubiquitin conjugation in response to oxidative stress in the lens.

Accumulation of damaged proteins is a major age-related change in lenses of virtually all species and is associated with lens opacification. Proteolytic removal of the damaged proteins may play an important role in maintaining the transparency of the lens. In many tissues, selective removal of abnormal or damaged proteins occurs via a ubiquitin-dependent proteolytic pathway. Ubiquitin, an 8.5 kDa polypeptide, selectively binds to proteins to form ubiquitin-protein conjugates. This ubiquitin-protein conjugate is, in most cases, a signal for protein degradation. In this work, age-related changes in rat lens in the following aspects were detected: (a) levels of the ubiquitin-protein conjugates, (b) some of the enzymes involved in ubiquitin conjugation in rat lenses, and (c) ability to respond to oxidative damage. Endogenous ubiquitin-protein conjugates were detected in epithelium, cortex and nucleus of lenses from young and old rats. The levels of endogenous high molecular weight (HMW) ubiquitin-protein conjugates in each developmental zone of the lenses from young rats were higher than that in the counterparts of lenses from old animals. Peroxide-treatment generally resulted in elevated levels of endogenous HMW ubiquitin-protein conjugates although masses of bulk proteins remain unchanged. The increases in ubiquitin-protein conjugates in the epithelial sections of young and old lenses upon oxidative stress were comparable. In the cortex of young lenses, there was a significant oxidation-related increase in ubiquitin-protein conjugates. There was a similar trend but diminished response in the cortex of old lenses. Nuclear fibers from young lenses also showed an oxidation-induced increase in the level of ubiquitin-protein conjugates. This response was not observed in nuclear fibers of old lenses. The ability to form HMW-ubiquitin conjugates with exogenous 125I-labeled ubiquitin in the lens also increased upon oxidative stress. The extent of the increase in the de-novo ubiquitin conjugating activity upon exposure to oxidation in old lens was much smaller than in young lens. Ubiquitin-activating enzyme (E1), and ubiquitin conjugating enzymes (E2(17k), E2(20k) and E2(25k) were detected by thiol ester assays or Western blot analysis. No significant age-related changes in the levels of E1, E2(17k), E2(20k) and E2(25k) were detected. The activity of E1 and E2(17k) increased upon exposure to H2O2. These data indicate that lens has the ability to increase ubiquitin conjugation activity in response to oxidative stress and this ability is attenuated upon aging. The age-related decrease in the ability to mount a ubiquitin-dependent response upon oxidation may contribute to the accumulation of damaged proteins in the old lenses.

Aging↗

PubMed1997

[Report of four cases of 22 channel cochlear implantations].

22 channel cochlear implants were implanted in 3 postlinguistical deafened adults and a prelinguistical deafened adolescent. All 4 patients including one with total cochlear ossification and another with congenital cochlear malformation showed significant auditory performance and demonstrated satisfactorily improved speech perception test scores postoperatively.

Adolescent↗

PubMed1997

[Carotid cavernous fistula (report of 14 cases)].

Fourteen cases of carotid cavernous fistula (CCF), including 9 cases of traumatic CCF and 5 cases of spontaneous CCF, were treated respectively or in combination with the ligation of the carotid, the isolation of the fistula, following clipping of its upper and lower reaches of the carotid, and endovascular treatment of balloons, steel coils, dry frozen dural pieces or Ivalon grains. It is considered that the detachable balloon endovascular embolization is a choice treatment for CCF.

Adult↗