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Biomedical subjects

H Guo

Publications and source records attributed to H Guo.

At least 73 records · Page 4Linked to original sources
PubMed2001

Activation of glycogen synthase kinase 3 beta (GSK-3beta) by platelet activating factor mediates migration and cell death in cerebellar granule neurons.

Children with vertically acquired HIV-1 can present with a rapidly progressive encephalopathy and neuronal apoptosis in the first 12-18 months of life. Furthermore, abnormal prenatal platelet activating factor (PAF) signalling may result in lissencephaly, a disorder of neuronal migration. PAF, produced from human immunodeficiency virus type 1 (HIV-1) -infected brain-resident macrophages, induces neuronal apoptosis in cultured cerebellar granule neurons (CGNs) in part by activating glycogen synthase kinase 3 beta (GSK-3beta). However, PAF can also inhibit migration of CGNs that are dispersed and allowed to reaggregate. Therefore, we investigated the biological effects following activation of GSK-3beta by PAF, and whether these effects were dependent on the culture conditions of the CGNs. We show here that activation of neuronal GSK-3beta by PAF is receptor-specific, with similar kinetics of activation in both monolayer cultures of CGNs that have ceased to migrate and reaggregate cultures of CGNs that are actively migrating. However, PAF receptor activation in reaggregated CGNs inhibits neuronal migration and induces approximately half the level of neuronal apoptosis compared with PAF-treated CGN cultures that have ceased to migrate. PAF-mediated inhibition of neuronal migration in reaggregated CGNs or induction of apoptosis in CGNs that have ceased to migrate can be reversed by either PAF receptor antagonists, or the GSK-3beta inhibitors lithium or valproic acid, in a dose-dependent manner. Abnormal PAF signalling that results in GSK-3beta overactivation may represent a common mechanism for pathological defects in neuronal migration in the prenatal period and neuronal apoptosis in the postnatal period.

Animals↗
PubMed2001

Ventricular tachycardia with QRS configuration similar to that in sinus rhythm and a myocardial origin: differential diagnosis with bundle branch reentry.

INTRODUCTION: Tachycardia with a QRS configuration which resembles that in sinus rhythm is usually thought to be supraventricular. Ventricular tachycardia, with a similar QRS configuration to that in sinus rhythm on the 12-lead ECG, can occur. The mechanisms of this form of ventricular tachycardia have not been previously reported. METHODS AND RESULTS: The mechanism of ventricular tachycardia was defined during electrophysiological study in five patients. During sinus rhythm, all patients had a wide QRS complex (>0.12 s) on the 12-lead ECG. The morphology remained grossly unchanged during spontaneous, symptomatic tachycardia. Four of the five patients had coronary artery disease and left ventricular dysfunction. The remaining patient had idiopathic dilated cardiomyopathy. The relationship between the His bundle, deflection, the right bundle branch and the QRS complex was evaluated during tachycardia. Atrial and ventricular pacing, and ventricular activation mapping were performed during tachycardia to define the tachycardia mechanism. The tachycardia induced at electrophysiological testing, which was similar to the clinical tachycardia, was proven to be ventricular tachycardia in each patient. The morphology of ventricular tachycardia was right bundle branch block in two patients and left bundle branch block in three patients. The median tachycardia cycle length was 300 ms (range: 260-480 ms). His bundle activation occurred in a 1:1 relationship with ventricular activation during tachycardia in all patients at least intermittently. The tachycardias were thought initially to be bundle branch reentry tachycardia. With further intervention and continued observation, it became clear that His bundle activation was passive and was not required for the tachycardia to sustain. During tachycardia, His bundle activation appeared to precede the local ventricular activation. Instead, the His bundle was activated slowly from the previous ventricular beat causing a long ventricular-His (VH) interval. This was shown by: (1) activation patterns, (2) response to pacing, (3) intermittent VH dissociation, and (4) termination of ventricular tachycardia. CONCLUSION: A unique form of ventricular tachycardia is described. The QRS complex morphology on the 12-lead ECG during tachycardia was grossly similar to that during sinus rhythm. The His bundle activation was passive and occurred with a long activation time from the ventricle to the His bundle. Although it mimics usual bundle branch reentry, this form of ventricular tachycardia appears to be due to a different mechanism in which the His bundle is not obligatory for the continuation of the reentrant phenomenon.

Adult↗
PubMed2001

Cdk5 mediates changes in morphology and promotes apoptosis of astrocytoma cells in response to heat shock.

The cyclin-dependent kinase member, Cdk5, is expressed in a variety of cell types, but neuron-specific expression of its activator, p35, is thought to limit its activity to neurons. Here we demonstrate that both Cdk5 and p35 are expressed in the human astrocytoma cell line, U373. Cdk5 and p35 are present in the detergent-insoluble cytoskeletal fraction of this cell line and Cdk5 localizes to filopodia and vinculin-rich regions of cell-matrix contact in lamellopodia. When exposed to a 46(o)C heat shock, U373 cells change shape, lose cell-matrix contacts and show increased levels of apoptosis. To test whether Cdk5 activation might play a role in these events, U373 cells were stably transfected with histidine-tagged or green fluorescent protein-tagged constructs of Cdk5 or a dominant negative mutation, Cdk5T33. Under normal growth conditions, growth characteristics of the stably transfected lines were indistinguishable from untransfected U373 cells and Cdk5 localization was not changed. However, when subjected to heat shock, cells stably transfected with Cdk5-T33 remained flattened, showed little loss of cell-matrix adhesion, and exhibited significantly lower levels of apoptosis. In contrast, cells that overexpressed wild-type Cdk5 showed morphological changes similar to those seen in untransfected U373 cells in response to heat shock and had significantly higher levels of apoptosis. Heat-shocked cells showed changes in p35 mobility and stability of the Cdk5/p35 complex consistent with endogenous Cdk5 activity. Together these findings suggest that endogenous Cdk5 activity may play a key role in regulating morphology, attachment, and apoptosis in U373 cells, and raise the possibility that Cdk5 may be a general regulator of cytoskeletal organization and cell adhesion in both neuronal and non-neuronal cells.

Apoptosis↗
PubMed2001

Vascular expression of integrin-associated protein and thrombospondin increase after mechanical injury.

BACKGROUND: Integrin-associated protein (IAP) is a thrombospondin (TSP)-binding, Gi protein-coupled cell surface receptor. The vascular function of IAP has not been defined, and it is not known whether TSP and IAP are expressed at the same time in injured arteries. METHODS: Left brachial arteries of baboons were injured using balloon withdrawal technique. Arteries were harvested 1 week after injury, and immunohistochemistry and in situ hybridization were performed using standard techniques. Uninjured right brachial arteries served as a control. Proliferation studies were performed using cultured human aortic smooth muscle cells (SMC). RESULTS: We found significant IAP expression in the media and neointima 7 days after injury using BRIC-126, an immunoglobulin (Ig) G2b monoclonal antibody that recognizes IAP with high specificity. In contrast, IAP staining in the uninjured vessel was only observed in the endothelium. Concurrent with IAP expression, TSP mRNA and protein expression in the neointima and media was enhanced 1 week after injury. In cultured SMC, activation of IAP was sufficient to elicit a proliferative response. TSP-induced proliferation was inhibited by antibodies that block TSP binding to IAP and mimicked by 4N1K, a 10-amino acid peptide derived from the IAP binding site within the carboxyl terminus of TSP. CONCLUSIONS: Vascular expression of IAP and TSP increased after mechanical injury and activation of IAP elicited a proliferative response in cultured SMC. These findings support the hypothesis that IAP participates in vascular healing responses.

Animals↗
PubMed2001

[The establishment of three-dimensional soft tissue facial reconstruction and morphometry].

OBJECTIVE: To establish a digital three-dimensional facial soft tissue morphometry and reconstruction system for orthodontic diagnosis and analysis of the facial soft tissue. METHODS: Three-dimensonal characteristics of facial soft tissue were captured by 4 digital cameras of high resolution. The developed hardware and software system and stereophotogrammetry were used for three-dimensional facial soft tissue reconstruction and morphometry at the same time. RESULTS: The three-dimensional facial soft tissue were successfully reconstructed with high reality and the three dimensional facial image can be rotated, moved and zoomed on the purpose. The system has the following advantages: (1) rapid capture of the facial image within 1 second or so, (2) accurate identification of facial landmark within 0.5 mm of resolution, (3) easy manipulation, (4) no exposure to radiation. CONCLUSIONS: The established system has proved to be effective for three-dimensional facial soft tissue diagnosis and analysis with the advantages of high resolution, high speed and, no exposure to radiation.

Face↗
PubMed2001

Immunity induced by DNA vaccine of plasmid encoding the rhoptry protein 1 gene combined with the genetic adjuvant of pcIFN-gamma against Toxoplasma gondii in mice.

OBJECTIVE: To construct the eukáryotic expression recombinant plasmid, pcIFN-gamma, as a genetic adjuvant and observe the immune responses elicited by pcDNA3-rhoptry protein 1 (pc-ROP1) combined with pcIFN-gamma against Toxoplasma gondii (T. gondii) infection in mice. METHODS: A fragment of the IFN-gamma gene was directly inserted into the pcDNA3 plasmid and identified by two restriction endonucleases digestion. pcIFN and pcROP1 DNA was injected into the left leg muscle of mice at a dosage of 100 micrograms, and a booster vaccination was given at the same dosage after two weeks. Control groups were injected with pcDNA3 blank plasmid or normal saline. At 30, 50 and 70 days after booster injection, kinetic tests were carried out: MTT assay for the proliferation response of T lymphocyte cells and the activity of NK cells, sandwich ABC-ELISA for the determination of IFN-gamma, IL-2 and IL-10; a serum enzymetic aassay for nitric oxide (NO) in sera and ELISA for the titer of IgG antibody in sera. RESULTS: The recombinant plasmid, pcIFN-gamma was constructed. The proliferation response of spleen T lymph cells, NK cell killing activity, and serum levels of IFN-gamma, IL-2 and NO in mice injected with pcROP1 and pcIFN-gamma were higher than in those injected with pcROP1 alone. There was no difference in IgG antibody levels between the two groups. CONCLUSION: The genetic adjuvant, pcIFN-gamma, could enhance the cellular immune response induced by DNA vaccine of pcROP1 in mice against Toxoplasma gondii infection.

Animals↗
PubMed2001

Construction of a recombinant plasmid harbouring the rhoptry protein 1 gene of Toxoplasma gondii and preliminary observations on DNA immunity.

OBJECTIVE: To observe the immune responses elicited in BALB/c mice by a DNA vaccine. A gene encoding rhoptry protein 1 (ROP1) from Toxoplasma gondii (T. gondii) was cloned into vector pcDNA3. METHODS: Amplifyied gene fragments coding for ROP1 from the genomic DNA of T. gondii ZS2 were inserted into cloning vector, pUC18, and sub-cloned into pcDNA3. Mice were injected at a dosage of 100 micrograms recombinant plasmid DNA by intramuscular injection and boosted after 2 weeks. pcDNA3 and normal saline were used as control. 30, 50 and 70 days after the second immunization, NK cell activity, T lymphocyte proliferation and sub-clusters and serum IgG antibody were assayed. RESULTS: The specific gene fragment coding for ROP1 was amplified and a pcROP1 recombinant was constructed. At 30 days after immunization, the spleens of the mice were obviously enlarged evidently. NKC activity and the proliferation of spleen T lymphocytes seen on MTT assay were higher in pcROP1 group than in the controls. The number of CD4+ T cells exhibited no obvious increase compared with that of the control, but CD8+ T cells were obviously increased (P < 0.05). At 90 days after vaccination, the titer of IgG antibody in the serum of vaccinated mice was positive (1:100). CONCLUSION: pcROP1 was constructed and it could elicit both cellular and humoral immune responses in immunized mice.

Animals↗
PubMed2001

[Effect of fibrinogen on corrosion behavior of stainless steel in artificial blood solution].

The effect of fibrinogen on corrosion behavior of SUS316L and SUS317L stainless steel in artificial blood PBS solution has been investigated with electrochemical technology. The results showed that the corrosion potential (Ec) of stainless steel shifted negatively, the passivated current (ip) became less and the pitting corrosion potential (Eb) shifted negatively with the existence of fibrinogen in PBS. These indicate that samples become more sensitive to corrosion under this circumstance. SEM pictures demonstrated that stainless steel adsorbed fibrinogen on its surface.

Adsorption↗
PubMed2001

[Effect of Cu and As and their combination pollution on Glycine max].

Experiments are carried out with hoagland cultivation to study the effects of Cu and As and their interactions on the germination and seedling growth of Glycine max. The results show that Cu or As pollution reduced proteinase activities, inhibited the seedling growth and the respiration rate of germinating seed of soybean. The inhibition increased as Cu and As concentration increased, POD activities increased with increasing Cu and As concentration. Cu pollution has an antagonistic effect against the pollution of As, and vise versa.

Arsenic↗
PubMed2001

[Study on the compliance of antihypertensive drugs in patients with hypertension].

OBJECTIVE: To study the compliance of antihypertensive drugs and its related factors in inpatients and outpatients patients with hypertension. METHOD: Clinical data of 816 inpatients and 497 outpatients were reviewed to study the compliance of antihypertensive drugs and related factors as well as to investigate the utilization of anti-hypertensive medicament, the incidence of the side-effect of the medication and to explore the difference of the blood pressure control between the compliant group and the uncompliant group. RESULTS: The main risk factors of the hypertensive patients were in the order as: disorder of lipometabolism, smoking, left ventricular hypertrophy (LVH) and Diabetes mellitus. Sixty point nine percent of the inpatients were followed up. The incidences of compliance were 63.4% in the inpatients, 77.3% when being discharged, and 43.7% in the outpatients. The cause of uncompliance were as follows: side-effect of the medication, failure to control BP, financial problems, etc. Data gathered during follow up period, it was found the side effect of the calcium antagonist and the diuretics improved palpably. Those compliers controlled their BP well, while little fluctuation of BP was observed. However, the uncompliers showed different pictures, and the range of fluctuation of BP was large. CONCLUSIONS: The compliance of the medicament was best among the outpatients to the discharge order, and the compliance of the outpatients was the worst.

Adrenergic beta-Antagonists↗
PubMed2001

[Immunohistochemical and clinical studies on sub-corneal flap epithelial implantation accompanied by flap melting after excimer laser in situ keratomileusis].

OBJECTIVE: To study the immunohistochemical and clinical characteristics of the corneal epithelial cells implanted under the flap accompanied by the flap melting after excimer laser in situ keratomileusis (LASIK) and the method of management. METHODS: In eight eyes (In 4 eyes a part of the flap melted.) with corneal epithelial cells implanted under the flap after LASIK, the corneal flap was torn again. The implanted tissue was removed. After washing between the interfaces, the flap was repositioned. The implanted tissue was immunohistochemically stained by using four kinds of monoclonal antibodies and using terminal deoxyribonucleotide transferase-mediated dUTP nick end labeling (TUNEL) method. RESULTS: Early in the course, the disorder appeared on the temporal side, expanded and thickened. The defective periphery of the corneal flap presented as a partial lunar eclipse. The melting process was self-limited in 3 months. The result was good after the implanted tissue was removed. The implanted material was stained by using HE, immunohistochemical and TUNEL methods. Some vesicle-like degeneration in the implanted layer was found. There was lysozyme in the vesicles, and the cells of implanted layer possessed a trend of apoptosis. All the cells were dead in the vesicles. CONCLUSIONS: The progress of corneal epithelial implantation under corneal flap after LASIK may include 3 periods: epithelial implantation, corneal flap melting and self-limitation. Early in the course, the implanted material presented as a thin film. Afterwards, it becomes a non-structural material. Possibly the melting of the corneal flap is caused by apoptosis. Therefore, the implanted epithelium should be removed early.

Adult↗
PubMed2001

[Study on quantitative relationship between retention parameters of solutes in reversed-phase liquid chromatography].

A quantitative relationship between lg I (a constant relating to the affinity of one mole of solute to stationary phase) and Z (total moles of organic solvent released at the contact region as one mole solute adsorbed by stationary phase) in the stoichiometric displacement model for retention (SDM-R) of solute was compared with the corresponding relationship in Snyder's Equation in reversed-phase liquid chromatography (RPLC). It was found that the relationship from SDM-R was more exact than that from Snyder's Equation. The linearity depends on the ranges of both lg I and lg Kw0. The broader the range, the better the linearity is. This conclusion conflicts to that reported in references in which the linearity only exists either when one factor dominates solute retention, or when it is completely dominated by statistics. The linear relationship in SDM-R and in Snyder's Equation was found valid not only for homologues but also for non-homologues.

Chromatography, High Pressure Liquid↗
PubMed2001

Surgical treatment of malignant esophageal tumors in PUMC Hospital.

To study how to prolong the postoperative survival time of the patients with malignant esophageal tumors. The clinical data of 1098 patients with malignant esophageal tumors from 1961 to 1992 were retrospectively analyzed. The deletion of fragile histamine triplet (FHIT) gene (a tumor suppressor gene) in 30 fresh esophageal samples obtained in 1996 was detected with PCR and RT-PCR method. The resectability was raised gradually and the operative morbidity and mortality decreased year by year, but there was no significant improvement on the postoperative 5-year survival rate. Delayed diagnosis and irradical resection influenced the long-term survival. The deletion of cDNA of FHIT gene was 64. 2% in esophageal cancer and 20% in the resected margin of the cancer. We believe that high-grade atypical hyperplasia in esophageal epithelium and deletion of FHIT gene in esophageal cancer and its resected margin are pathological and molecular markers for early diagnosis of esophageal cancer respectively, and the latter may be one of the molecular markers for the resection. Early diagnosis and treatment, radical, resection, and postoperative nutritional support are very important for the improvement of the postoperative survival time of the patients.

Acid Anhydride Hydrolases↗
PubMed2001

[Induced tolerance to cardiac allografts with intrathymic injection of donor spleen cells].

OBJECTIVE: To study the methods and mechanisms of immune tolerance in cardiac transplantation. METHODS: Male DA rat hearts were transplanted to male Lewis rats using Ono's model and randomly divided into four groups: untreated (group I), intrathymic injection of 2.5 x 10(7) DA splenocytes to Lewis rat (group II), intraperitoneal injection of 1 ml rabbit anti-rat lymphocyte serum (ALS) to Lewis recipient (group III), intrathymic injection of 2.5 x 10(7) DA splenocytes combined with intraperitoneal injection of 1 ml rabbit anti-rat lymphocyte serum (ALS) to Lewis recipient (group IV). 21 days later heart transplantation was performed. Mean survival time (MST), histological changes and mixed lymphocyte reaction (MLR) were measured after operation. RESULTS: In the group of intrathymic injection of spleen cells combined with ALS treatment, the survival time of heart allografts [MST: (81.8 +/- 7.6)d] was significantly longer than in the groups I [MST: (7.3 +/- 1.0) d], group II [MST:(7.8+/- 1.0)d], and group III [MST(8.2 +/- 1.2) d, P < 0.01]. Only a few inflammatory cells infiltrated in cardiac allografts in group IV. MLR of group IV were significantly decreased compared with those of the normal control (P < 0.01). CONCLUSIONS: The role of thymus as a special site for induction and maintenance of specific immunological unresponsiveness to organ allografts was confirmed. T cell clonal deletion may play an important role in this immune tolerance.

Animals↗
PubMed2000

Effect of incompressibility on lateral instabilities of polymer brushes in a poor solvent.

We report a theoretical investigation of the lateral instability of grafted polymer layers in a poor solvent. Within self-consistent mean-field theory, we carry out a linear stability analysis at the random phase approximation level, for which an explicit incompressibility condition is enforced. Our analysis predicts a stability diagram in which regions of stable and unstable polymer brush profiles are located. Compared with analysis where incompressibility is not taken into account, our results suggest that lateral stability is enhanced.

Journal Article↗
PubMed2000

Nitric oxide-dependent ribosomal RNA cleavage is associated with inhibition of ribosomal peptidyl transferase activity in ANA-1 murine macrophages.

NO can regulate specific cellular functions by altering transcriptional programs and protein reactivity. With respect to global cellular processes, NO has also been demonstrated to inhibit total protein synthesis and cell proliferation. The underlying mechanisms are unknown. In a system of ANA-1 murine macrophages, iNOS expression and NO production were induced by exposure to endotoxin (LPS). In selected instances, cells were exposed to an exogenous NO donor, S-nitroso-N-acetylpenicillamine or a substrate inhibitor of NO synthesis. Cellular exposure to NO, from both endogenous and exogenous sources, was associated with a significant time-dependent decrease in total protein synthesis and cell proliferation. Gene transcription was unaltered. In parallel with decreased protein synthesis, cells exhibited a distinctive cleavage pattern of 28S and 18S rRNA that were the result of two distinct cuts in both 28S and 18S rRNA. Total levels of intact 28S rRNA, 18S rRNA, and the composite 60S ribosome were significantly decreased in the setting of cell exposure to NO. Finally, 60S ribosome-associated peptidyl transferase activity, a key enzyme for peptide chain elongation, was also significantly decreased. Our data suggest that NO-mediated cleavage of 28S and 18S rRNA results in decreased 60S ribosome associated peptidyl transferase activity and inhibition of total protein synthesis.

Animals↗