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Biomedical subjects

G Chen

Publications and source records attributed to G Chen.

At least 217 records · Page 12Linked to original sources
PubMed2001

[Study on the transformation from myelodysplastic syndromes into acute leukemias].

OBJECTIVE: To study the patterns of transformation from myelodysplastic syndromes (MDS) into acute leukemias (AL). METHODS: Leukemic transformation of MDS patients was dynamically followed up and the clinical manifestations, peripheral blood and bone marrow pictures, karyotypes, immunophenotypes, response to treatment and prognosis of post MDS acute leukemia (postMDS-AL) were observed. RESULTS: During the past eight year and seven months, 21 (13.91%) of 151 MDS patients progressed to overt leukemia with a median interval of 5 (1 - 21) months. There were no significant differences among the rates of leukemia from RA, RAEB and RAEB-t groups. The transformation was developed either gradually or rapidly. There were five parameters related to the leukemic transformation: under 40 years of age, pancytopenia, more than 0.15 blasts in bone marrow, at least two types of abnormal karyotype and combined chemotherapy. All of the 21 post MDS-AL were acute myeloid leukemia (AML); and most of them were M(2), M(4) and M(5). Two (9.52%) post MDS-AML developed extramedullary infiltration. Leukopenia was found in 47.62% of patients. Two third of the patients, whose bone marrows were generally hypercellular, showed neutropenias. After evolving into AML, 8 (47.06%) patients developed abnormal karyotypes. High expression of immature myeloid antigens, including CD(33) (49.83 +/- 24.50)%, CD(13) (36.38 +/- 33.84)%, monocytic antigen CD(14) (38.50 +/- 24.60)%, and stem cell marker CD(34) (34.67 +/- 30.59)% were found on bone marrow mononuclear cells of post MDS-AML cases. In some cases, lymphoid antigens, such as CD(5), CD(7), CD(9) and CD(19) were coexisted with myeloid antigens. A low complete remission rate (31.25%) and short survival duration with median survival of 6 (1 - 28) months were found in patients with post MDS-AML treated by induction therapy. CONCLUSION: MDS was at high risk of evolving into AML, either gradually or rapidly. Patients with post MDS-AML had specific biologic features and worse prognoses.

Acute Disease↗
PubMed2001

[Association between renin activity, angiotensin II and ovarian hyperstimulation syndrome].

OBJECTIVE: To investigate the association between renin-like activity (RA) and angiotensin II (A II) and the ovarian hyperstimulation syndrome (OHSS). METHODS: Blood samples were taken from 42 patients undergoing in vitro fertilization (IVF). According to the ovarian stimulating response, the patients were divided into 4 groups: group I, low responders, 7 cases; group II, moderate responders, 8 cases; group III a high responders without using albumin, 7 cases, group III b, high responders with albumin, 10 cases; group IV, severe and moderate OHSS, 10 cases. 5 patients for intrauterin insemination with natural cycle as control. Follicular fluid (FF) was collected at oocyte retrieval from 28 IVF patients (including 7 OHSS patients). Fluid from ascites and hydrothorax was obtained from 3 OHSS patients, and peritoneal fluid obtained from 5 infertility patients by laparoscopy and ascitic fluid obtained from 6 ovarian carcinoma patients served as control. RA and A II levels were measured by radioimmunoassay. RESULTS: Plasma RA and A II levels at mid-luteal phase from OHSS patients [(19.9 +/- 19.0) micrograms.L-1.h-1 and (397.0 +/- 378.2) ng/L] were significantly higher than those from the other patients (P < 0.01-0.05), also the levels at mid-luteal phase from IVF patients were significantly higher than those at late-follicular phase [(4.1 +/- 2.9)-(4.9 +/- 3.2) micrograms.L-1.h-1 Vs (1.5 +/- 0.9)-(1.9 +/- 1.0) micrograms.L-1.h-1, (85.5 +/- 49.5)-(109.4 +/- 46.0) ng/L Vs (33.6 +/- 15.9)-(37.0 +/- 17.1) ng/L, P < 0.01-0.05]. RA and A II levels in FF were significant higher than those in plasma (P < 0.01-0.05). A II in ascitic fluid in OHSS patients was 4 to 8 times higher than that in plasma, while RA in ascitic fluid was 1.5 to 3 times higher than that in plasma, but the levels of A II and RA in controls were very low. The plasma RA and A II levels dropped very significantly along with clinical improvement (P < 0.01). CONCLUSION: These findings suggest that RA and A II are associated with the pathogenesis of capillary leakage in OHSS.

Angiotensin II↗
PubMed2001

[Isolation of HIV-1 from infected individuals in Fujian Province].

OBJECTIVE: To isolate the virus from HIV-1 infected individuals. METHODS: Blood specimens were collected from 10 HIV-1 infected persons in Fujian Province. Peripheral blood mononuclear cells (PBMCs) were separated from the heparinized blood. Each sample was cocultured with fresh normal PBMCs to isolate HIV-1. Supernatant of the cocultures was tested by using HIV-1 P24 antigen Kit. RESULTS: Of the 10 specimens, 9 showed positive for the P24. 4 of 9 isolated infected MT4 cells, and cell syncytias could be seen. Three isolates showed transient infection of MT4, which probably belong to slow/low virus. Only one isolate could infect MT4 successively, which had been passed for 15 generations without significantly changed viral titer; it is believed to be a rapid/high replication virus. CONCLUSIONS: HIV-1 virus was successfully isolated.

HIV Infections↗
PubMed2001

Informant-rated cognitive symptoms in normal aging, mild cognitive impairment, and dementia. Initial development of an informant-rated screen (Brief Cognitive Scale) for mild cognitive impairment and dementia.

An informant-rated cognitive screen may have the potential to reliably help detect early dementia. A valuable scale should have good interitem associations and strong reliability when tested in groups with and without cognitive impairment. Our scale, the Brief Cognitive Scale (BCS), consists of 18 questions designed to assess cognitive function that affects everyday activities. Each question is coded with one of four levels, ranging from no impairment to severe impairment. We administered this screen to 120 subjects: 26 controls, 28 with a diagnosis of mild cognitive impairment (MCI), and 66 with a diagnosis of dementia. In addition, we administered a Folstein Mini-Mental Status Examination (MMSE) to each subject. Our results showed that the BCS scores were lowest in the control group and highest in the dementia group. In our sample, this scale was effective at discriminating between subjects with no cognitive impairment, MCI, and dementia. However, the scale needs further refinement before it can be employed in a clinical setting.

Aged↗
PubMed2001

[Effects of angiotensin II on proliferation and expression of interleukin-6 of human kidney fibroblasts].

OBJECTIVE: To investigate the effects of Angiotensin(Ang) II on the proliferation and expression of Interleukin (IL)-6 in human kidney fibroblasts(KFB). METHODS: The human KFB were cultured and identified, the proliferation of KFB was measured by MTT, and the level of IL-6 was measured by radioimmunoassay(RIA). RESULTS: Angiotensin II could stimulate the proliferation of KFB and enhance the expression of IL-6 in protein level on KFB. CONCLUSION: Angiotensin II can stimulate KFB's proliferation and enhance the expression of IL-6 of KFB. These findings suggest that Ang II might play a part in the mechanisms for modulating tubulointerstitial changes and induceing renal fibrosis.

Angiotensin II↗
PubMed2001

[Purification and properties of endoglucanases from Aspergillus aculeatus SM-L22].

The five endoglucanases(CMCase) components from Aspergillus aculeatus SM-L22 were separated and purified by exclusion chromatography and ion-exchange chromatography. Five components(EG II-1, EG II-2, EG III-1, EG III-2 and EG IV) had molecular weights of 38.7, 34.4, 31.4, 36.9 and 23.7 kD by SDS-PAGE, respectively, and IEF showed their pI were pH < 3.5, < 3.5, 4.9, 4.4 and 5.0, respectively. All of them have maximum reactive activities at pH 3.5-4.0; and the optimum temperatures were 55 degrees C, 60 degrees C, 60 degrees C-70 degrees C, 60 degrees C-70 degrees C and 60 degrees C, respectively. EG II-1 and EG II-2 can only act such morphological substrates as CMC or phosphated cellulose, but EG III-1, EG III-2 and EG IV can active xylan also. The activities of all components were stimulated by Fe2+ except EG IV, EG III-2 was activited mostly by Fe2+. The kinetics' showed that there were no relativies between the affectivity of cellulases and its Km.

Aspergillus↗
PubMed2001

[Study on the construction of DYS385 allelic ladder and the genotype distribution in two populations].

OBJECTIVE: We have designed a new method to produce standard DYS385 allelic ladder in order to solve the problem of the accuracy and standardization of STR-PCR typing in forensic practice. METHODS: Nine different PCR amplified DYS385 allelic fragments were isolated from the gel, eluted into the distilled water and reamplified by PCR. The purified allelic fragments were then blunt-end subcloned individually into the pUC plasmid vectors and transfected into competent E. coli DH5 alpha cells. The sequencing results confirmed that the size and the constructure of the inserts were correct. The recombinant plasmids DNA with 9 inserts were then used as templates for reamplification to generate DYS385 standard ladder. RESULTS: A large quantity of standard DYS385 allelic ladder was obtained, with which the genetic polymorphisms of DYS385 locus both in Chinese Han and German populations were studied. CONCLUSION: The STR standard ladder constructed by this method has high value in the forensic application, and the DYS385 locus is robust for forensic analysis.

Alleles↗
PubMed2001

[Simultaneous determination of trace cadmium and arsenic in grains using atomic absorption spectrophotometry].

Simultaneous determination of two components in single wavelength using interferencing effect and atomic absorption spectrophotometry assisted by simulated annealing-back propagation of error-artificial neural networks algorithm was realized, and simultaneous determination of trace cadmium and arsenic in grains was studied. The results obtained are satisfactory. The recoveries found by standard addition method are 91%-98% and 87%-92% respectively. Relative standard deviations for 7 times of determinations are all less than 4%. This method is fast and simple.

Arsenic↗
PubMed2001

[Analysis of the content of ten kinds of metal elements in cerebrolysin by atomic absorption spectrophotometry].

The contents of Mg, K, Ca, Cr, Mn, Fe, Co, Ni, Cu and Zn in eight different brand cerbrolysins were determined by flame atomic absorption spectrophotometry. The statistical results as follows: the metal elements have significant difference between in seven kinds of Chinese products and in the cerebrolysin made by Austria. According to the results, we studied the inter relation of metal elements with medicine result, and analyzed the effect of trace elements in cerebrolysin. It provided useful data for medicine on clinical practice.

Amino Acids↗
PubMed2001

[External irradiation combined with intracavitary brachytherapy for esophageal cancer].

OBJECTIVE: To study the long-term treatment results and acute irradiation response as well as complications following external irradiation combined with intracavitary brachytherapy. METHODS: After loading intracavitary brachytherapy was used for patients with esophageal cancer. In 92 patients with esophageal cancer, 47 (group A) were treated with external irradiation only, and 45 (group B) with external irradiation and brachytherapy. The doses were 60.0 Gy - 70.0 Gy per 6-7 week for external irradiation, using 8 or 10 MV liner accelerator, and 5.0-8.0 Gy per fraction for intracavitary therapy. RESULTS: There was a significant difference in acute response and complications as well as local recurrence rate between the two groups (P < 0.05). The survival rates of groups A and B at 1,3 and 5 years were 59.6%, 25.6%, 10.6% and 80.0%, 46.7%, 26.7% respectively (P < 0.05 respectively, using chi2 test). The complications related to intracavitary irradiation were esophageal perforation, esophagorrhagia, esophagotracheal fistula and esophageal narrowing. 66 patients died and 9 lost follow-up, giving a follow up rate of 90.2%. CONCLUSION: External irradiation combined with afterloading intracavitary brachytherapy for esophageal cancer can reduce the local recurrence and enhance the long-term survival but with an increase of complications compared with the patients treated with external irradiation alone.

Adult↗
PubMed2001

Liver transplantation for patients with hepatitis B virus-related diseases.

OBJECTIVES: To summarize the results of the orthotopic liver transplantation (OLT) for HBV-related diseases and assess the efficiency of lamivudine on preventing HBV recurrence. METHODS: From April 1993 to December 2000, 54 patients with HBV-related liver disease were treated by OLT at the Transplantation Center of Sun Yet-sen University of Medical Sciences (SUMS). Seventeen patients who had postnecrotic cirrhosis (PNC) as a result of HBV infection were designated as group 1; 25 patients coexisting hepatocellular carcinoma (HCC) served as group 2; the remaining 12 patients who had no liver disease but fulminant hepatic failure (FHF) due to HBV infection served as group 3. The survival rate, the causes of early death and the HBV recurrence rate under lamivudine monotherapy were retrospectively analyzed. RESULTS: The overall survival rate within 2 months of transplantation was 75.9% and the morbidity in group 3 was obviously higher than in group 1 and group 2; the outcome patients with small HCC was superior to that of patients with large HCC; lamivudine monotherapy can effectively prevent and treat HBV recurrence while no side effect attributable to it had been identified. CONCLUSION: Combined with the use of lamivudine, liver transplantation can be justified in patients with fulminant hepatitis B, hepatitis B-related liver cirrhosis and coexisting small HCC or even selected large HCC.

Antiviral Agents↗
PubMed2000

Carboxyl residues in the active site of human phenol sulfotransferase (SULT1A1).

The carboxyl-specific amino acid modification reagent, Woodward's reagent K (WK), was utilized to characterize carboxyl residues (Asp and Glu) in the active site of human phenol sulfotransferase (SULT1A1). SULT1A1 was purified using the pMAL-c2 expression system in E. coli. WK inactivated SULT1A1 activity in a time- and concentration-dependent manner. The inactivation followed first-order kinetics relative to both SULT1A1 and WK. Both phenolic substrates and adenosine 3'-phosphate 5'-phosphosulfate (PAPS) protected against the inactivation, which suggests the carboxyl residue modification causing the inactivation took place within the active site of the enzyme. With partially inactivated SULT1A1, both V(max) and K(m) changed for PAPS, while for phenolic substrates, V(max) decreased and K(m) did not change significantly. A computer model of the three-dimensional structure of SULT1A1 was constructed based on the mouse estrogen sulfotransferase (mSULT1E1) X-ray crystal structure. According to the model, Glu83, Asp134, Glu246, and Asp263 are the residues likely responsible for the inactivation of SULT1A1 by WK. According to these results, five SULT1A1 mutants, E83A, D134A, E246A, D263A, and E151A, were generated (E151A as control mutant). Specific activity determination of the mutants demonstrated that E83A and D134A lost almost 100% of the catalytic activity. E246A and D263A also decreased SULT1A1 activity, while E151A did not change SULT1A1 catalytic activity significantly. This work demonstrates that carboxyl residues are present in the active site and are important for SULT1A1 catalytic activity. Glu83 and E134 are essential amino acids for SULT1A1 catalytic activity.

Amino Acid Sequence↗
PubMed2000

Intra-cerebellar infusion of NMDA receptor antagonist AP5 disrupts classical eyeblink conditioning in rabbits.

Rabbits were infused with AP5, an NMDA receptor antagonist, into the region of the cerebellar interpositus nucleus during classical eyeblink conditioning with a tone conditioned stimulus and an air puff unconditioned stimulus. Acquisition of the conditioned eyeblink response was delayed in rabbits infused with AP5 but the NMDA receptor antagonist had little effect on conditioned responses when these same rabbits were infused a second time after reaching asymptotic responding levels. Some rabbits that received AP5 infusions for the first time after the conditioned response was well learned showed temporary alterations in response timing. These data indicate that NMDA receptor activity is involved in the acquisition of classically conditioned eyeblink response and may also be involved in regulating cellular processes involved in response timing and other aspects of conditioned response execution.

2-Amino-5-phosphonovalerate↗
PubMed2000

Identification and characterization of a novel gene KE04 differentially expressed by activated human dendritic cells.

To better understand the molecular mechanisms of dendritic cells (DC) function, we isolated differentially expressed genes in Ag-activated DC by a PCR-based subtractive hybridization technique. A novel full-length cDNA, KE04, was thus isolated from KLH-activated human PBMC-derived DC. KE04 cDNA encoded a 346-aa protein devoid of functionally indicative motifs. KE04 protein showed 64% identity with a Caenorhabditis elegans protein and 83% identity with a human putative protein. Distant relationship was also found with other prokaryotic and eukaryotic proteins. Differential expression of KE04 in activated DC other than nonactivated DC was confirmed at both mRNA and protein levels. KE04 mRNA expression was detectable in various human tissues and cell lines by Northern blot and RT-PCR. Western blot and confocal microscopy analysis indicated that its cytolocalization was intracellular. Our data suggest the potential involvement of KE04 in DC activation and will facilitate the research of molecular mechanism of DC function.

Amino Acid Sequence↗
PubMed2000

Founder's Award, Society for Biomaterials. Sixth World Biomaterials Congress 2000, Kamuela, HI,May 15-20, 2000. Really smart bioconjugates of smart polymers and receptor proteins.

Over the past 18 years we have been deeply involved with the synthesis and applications of stimuli-responsive polymer systems, especially polymer-biomolecule conjugates. This article summarizes our work with one of these conjugate systems, specifically polymer-protein conjugates. We include conjugates prepared by random polymer conjugation to lysine amino groups, and also those prepared by site-specific conjugation of the polymer to specific amino acid sites that are genetically engineered into the known amino acid sequence of the protein. We describe the preparation and properties of thermally sensitive random conjugates to enzymes and several affinity recognition proteins. We have also prepared site-specific conjugates to streptavidin with temperature-sensitive polymers, pH-sensitive polymers, and light-sensitive polymers. The preparation of these conjugates and their many fascinating applications are reviewed in this article.

Acrylamides↗
PubMed2000

The p38 pathway provides negative feedback for Ras proliferative signaling.

Ras activates three mitogen-activated protein kinases (MAPKs) including ERK, JNK, and p38. Whereas the essential roles of ERK and JNK in Ras signaling has been established, the contribution of p38 remains unclear. Here we demonstrate that the p38 pathway functions as a negative regulator of Ras proliferative signaling via a feedback mechanism. Oncogenic Ras activated p38 and two p38-activated protein kinases, MAPK-activated protein kinase 2 (MK2) and p38-related/activated protein kinase (PRAK). MK2 and PRAK in turn suppressed Ras-induced gene expression and cell proliferation, whereas two mutant PRAKs, unresponsive to Ras, had little effect. Moreover, the constitutive p38 activator MKK6 also suppressed Ras activity in a p38-dependent manner whereas arsenite, a potent chemical inducer of p38, inhibited proliferation only in a tumor cell line that required Ras activity. MEK was required for Ras stimulation of the p38 pathway. The p38 pathway inhibited Ras activity by blocking activation of JNK, without effect upon ERK, as evidenced by the fact that PRAK-mediated suppression of Ras-induced cell proliferation was reversed by coexpression of JNKK2 or JNK1. These studies thus establish a negative feedback mechanism by which Ras proliferative activity is regulated via signaling integrations of MAPK pathways.

3T3 Cells↗