Biomedical subjects

L Jiang

Publications and source records attributed to L Jiang.

At least 109 records · Page 6Linked to original sources

PubMed2000

Application of laser Doppler flowmetry to measure cerebral microvascular perfusion in the fetal sheep.

Laser Doppler flowmetry (LDF) has been used to measure flow in various organs of the adult, but has not been applied to the mammalian fetus. The purpose of this study was to apply LDF to measure cerebral blood flow of the fetal sheep and to assess the possible errors and artifacts of the method caused by myometrial, fetal, and maternal movements. By three days after probe placement, the flow signal had decreased 55% from initial post surgical readings and thereafter it became stable. During fetal hypoxia, the signal increased 48% and during hypercarbia it increased 59%. After fetal death, the signal decreased to 48% of control level. After maternal death, it decreased to 9% and electrical zero could not be reached. LDF is useful to measure changes of fetal cerebral microvascular perfusion because it can provide continuous signals but care is required in data handling and probe fixation when used for the mammalian fetus.

Animals↗

PubMed2000

[Mutants of subtilisin E].

Ser 236, located in the surface of subtilisin E and at the end of alpha-helex with Ser221, is far from the active center (Asp32, His64, Ser221). The replacement of Ser236 with Cys via directed-mutagenesis should effect protease activity insignificantly and may be able to improve the stability of enzyme due to the potency to form disulfide across two molecules. The results indicated that BP-1 (Ser236Cys) was found to gain 150% activity (Kcat/Km value) of the wild-type subtilisin E and 3-fold increase in stability in aqueous solution at pH7.4 and 50 degrees C, compared to the wild-type enzyme. However, further mutations on BP-1 to introduce Ala15Asp/Gly20His (BU-1) or Ser24His/Lys27Asp (BW-1) was found negative effects on the activity and stability of subtilisin E.

Enzyme Stability↗

PubMed2000

[Reevaluation of the nomenclature and diagnostic criteria in 477 patients with severe hepatitis].

OBJECTIVE: To explore the possibility of establishing more reasonable nomenclatures and diagnostic criteria for patients with severe hepatitis (SH) through analyzing clinical data of 477 cases of SH. METHODS: The clinical characteristics and outcomes of SH were analyzed according to different criteria. RESULTS: Chronic severe hepatitis (CSH) made up 88.5% of total cases of SH. The survival rate in the patients with hepatic encephalopathy was much lower than that without hepatic encephalopathy. About 1/5 of cases of subacute severe hepatitis (SSH) and CSH had neither ascites nor hepatic encephalopathy. When the period of 2 weeks was used in replace of 10 days for the diagnosis for acute severe hepatitis (ASH), the newly added cases were consistent with the characteristics of ASH. CONCLUSION: We suggest dividing SH into 2 types: encephalopathy and non-encephalopathy by using the nomenclature of fulminant hepatitis and severe type hepatitis, respectively. The late-onset form should be added besides of acute form and subacute form. It seems to use the period of 2 weeks as the new definition of onset time for ASH. The criteria of dividing SH into 3 forms, i.e. ascites, encephalopathy and ascites plus encephalopathy, and the nomenclature recommended by the International Association for the Study of the Liver Subcommittee are not satisfactory when used in clinical cases. The typing of CSH remains to be clarified.

Adolescent↗

PubMed2000

[Site-directed mutagenesis and effects on the enzymatic properties of subtilisin E].

Site-directed mutagenesis was used to investigate the effects of S221C/P225A, N118S/S221C/P225A, D60N/N118S/S221C/P225A and Q103R/N118S/S221C/P225A mutations on the properties of Subtilisin E. It was found that S221C/P225A mutant is 73,000-fold decreased in amidase activity than subtilisin E and 3-fold increased than subtiligase in the ratio of esterase/amidase; N118S/S221C/P225A mutant has 3.6-fold and 15-fold decreased in amidase and esterase activity respectively and as a result, it has a 4-fold lower in the ratio of amidase/esterase than S221C/P225A mutant; Although it has no effect on the esterase activity, D60N/N118S/S221C/P225A mutant enhanced its ratio of amidase/esterase by 15 fold, 3.3-fold and 10.3 fold compared to N118S/S221C/P225A mutant, S221C/P225A mutant and subtiligase respectively; Q103R/N118S/S221C/P225A mutant, however, has a 5-fold enhanced in the amidase activity and 55-fold and 1000-fold decrease in the esterase activity and the ratio of esterase/amidase compared to N118S/S221C/P225A.

Amidohydrolases↗

PubMed2000

Dimethylamiloride-induced differentiation of HL-60 cells.

AIM: To study the effect of 5-(N,N-dimethyl) amiloride (DMA) on the proliferation and differentiation of HL-60 cells in vitro. METHODS: MTT assay to test cytotoxicity; cell staining and NBT reduction to test cell differentiation. RESULTS: DMA inhibited HL-60 cells growth in a concentration-dependent manner, and IC50 value for 96 h was 31.7 (95% confidence limits: 6.3-57.1) mumol.L-1. DMA also induced granulocytic differentiation in HL-60 cells. The percentage of differentiating cells increased from 6.5% to 70% after DMA 100 mumol.L-1 treatment for 3 d. The differentiating effect of DMA was distinguishable from amiloride, 5-(N-ethyl-N-isopropyl)amiloride (EIPA), and (5-(N-ethyl-N-isopropyl)amiloride (MIA). None among the amiloride, EIPA, and MIA were capable of triggering the differentiation of HL-60 cells. CONCLUSION: DMA inhibited the proliferation of HL-60 cells and induced differentiation of HL-60 cells.

Amiloride↗

PubMed2000

Embolic events in 93 elderly Chinese patients with atrial fibrillation.

OBJECTIVES: To evaluate the prevalence of embolic events and relevant factors in elderly Chinese patients with atrial fibrillation(AF), and to provide evidence on ways to prevent embolic events. METHODS: Autopsy data from ninety-three continous elderly Chinese patients with AF were analysed. The incidence of embolic events and its relationship to underlying disease, pathologic changes in the heart, and other clinical characteristics were examined. RESULTS: Embolism were observed in 27 of 93 cases, with an incidence of 29.03%. The incidence of embolic events was higher in elderly patients with rheumatic heart disease than those with coronary artery disease, hypertensive myocardiopathy and heart diseases. Patients with chronic AF, with a course of AF > or = 3 years, and those with heart failure or diabetes had a higher incidence of embolic events than those without these complications. There was significant difference in incidence between paroxysmal and chronic AF. Patients with left atrial or ventricular enlargement, mural thrombosis in cardiac chambers, valvular calcification and valvular vegetation also had a higher incidence of embolic events. Oral dipyridamole (75-150 mg/d) or aspirin (50-150 mg/d) showed no definite effects in preventing embolism in some patients. CONCLUSIONS: There was a high incidence of embolic events in elderly Chinese patients with AF. Anticoagulation therapy should be provided to the elderly patients with AF, especially to the patients with risk factors for embolism.

Aged↗

PubMed2000

Computer-aided 3-D reconstruction and measurement of the optic canal and intracanalicular structures.

OBJECTIVE: To reconstruct the human optic canal and its inner structures, and to provide detailed knowledge of this region for optic nerve decompression for further understanding on the pathologic mechanisms of indirect optic nerve injury. METHODS: Six optic canals and their inner structures were reconstructed using a computer-aided 3-dimensional reconstruction system. Quantitative measurement of the canal wall thickness, bony canal transverse area, optic nerve transverse area, dural sheath transverse area, subarachnoid space transverse area, and subarachnoid space volume were done by means of the computer morphometric analysis system. The detailed spatial relationship among intracanalicular structures were also carefully identified on the 3-D models. RESULTS: The thinnest portion of the canal was the middle part of the medial wall (0.45 +/- 0.35 mm) and the narrowest space was in the middle part of the optic canal (the transverse area was 18.21 +/- 2.50 mm2). The volume of subarachnoid space which can be considered the compensatory space for distention incurred by the hemorrhage, optic nerve edema, or hematoma was 21.16 +/- 4.31 mm3. At the cranial opening, the middle part and orbital opening, its transverse area was 4.45 +/- 1.12 mm2, 2.68 +/- 1.32 mm2 and 1.23 +/- 0.83 mm2, respectively. CONCLUSIONS: Since the compensatory space was limited, even a tiny amount of blood or swelling of the nerve may cause optic nerve compression. Because the narrowest space was in the middle part of the optic canal and the compensatory space for distention gradually decreases from cranial end to orbital end, the middle part and the anterior part of the optic canal and dural sheath are critical in optic nerve decompression.

Eye↗

PubMed2000

[The significance and characteristics of the gene expressions of c-fos and c-jun in hypertrophic scar and chronic ulcer tissues].

OBJECTIVE: To explore the characteristics and regularity of the expression of c-fos and c-jun genes in hypertrophic scar and chronic ulcer tissues and their relationship to different tissue restoration. METHODS: Tissue samples of hypertrophic scars were harvested from 16 cases of patients after burns and chronic cutaneous ulcers during operation together with the normal skin (n = 5) of the same patients as control. ABC method was employed to detect the gene expression of both c- fos and c-jun in above samples. RESULTS: The positive expression of c-fos and c-jun gene was found in epithelial basal cells and some subcutaneous fibroblasts in normal skin. But the expression of c-jun was weaker than that of c-fos in above tissues. A strong positive expression of c-fos and c-jun genes was found mainly in fibroblasts in the hypertrophic scar. But the combined expression of both tumor genes was most often found in the capillary endothelium, some inflammatory cells and the cytoplasm of fibroblasts in ulcer tissue. CONCLUSION: The results indicated that the amount and location of the expression of c-fos and c-jun genes were different in the three kinds of tissues, suggesting that these two tumor genes may play important roles in wound healing modulation.

Adult↗

PubMed2000

[Progress in the research on echinococcosis control].

Explore the source record for details and available documents.

Animals↗

PubMed2000

[Experimental safety study using rats and mice irradiated with the complex field cure instrument].

The complex field cure instrument is a new medical instrument. The complex field is composed of several sorts of physical quantum fields. Mice and rats are continuously irradiated by the complex field for 20 days to 90 days. The result shows that WBC, Hb and PLT value of the animals irradiated with the instrument are more than the control group, and their biochemical index is normal. The internal organs of the experimental animals show no toxicity. The visceval coefficient (liver, spleen) of the experimental animals is more than the control group. The marrow micronucleas test is negative. The chromosome test show no distortion. All of the results have proved that the instrument produces no toxicity side effect. Application of the instrument is safe and reliable and it may increase immune function of the body.

Animals↗

PubMed2000

[Investigation of connective tissue growth factor's gene cloning].

OBJECTIVE: The human connective tissue growth factor(CTGF), as the responsive product of immediate early gene, was cloned for the investigation of cellular primary gene responded and healing repairing. METHODS: RT-PCR was performed with the mRNA of HUVE cell stimulated, the three clones of CTGF, via mutational modified, were ligated to a complete gene that identified with sequencing. RESULTS: The sequencing indicated that this CTGF gene contains complete coding region and the 3'-noncoding region which is difference with the reported sequence. CONCLUSION: A new human CTGF gene was cloned.

Base Sequence↗

PubMed2000

[Determination of micro amounts of calcium and magnesium in saturated high purity sodium chloride solution by FAAS].

Micro amounts of calcium and magnesium in saturated high purity sodium chloride solution were determined by flame atomic absorption spectrometry after the preseparation of calcium and magnesium from matrix solution through ion-exchange resin column filled with model 401 chelate resin. The parameters and operating conditions of the preseparation of calcium and magnesium from matrix solution were studied by orthogonal optimization process. The relative standard deviations of this method were 6.5% and 5.5% for calcium and magnesium, respectively. The recoveries were 99% and 94% for calcium and magnesium, respectively.

Calcium↗

PubMed1999

Essential protein-protein interactions between Plasmodium falciparum thymidylate synthase and dihydrofolate reductase domains.

In Plasmodium falciparum, dihydrofolate reductase and thymidylate synthase activities are conferred by a single 70-kDa bifunctional polypeptide (DHFR-TS, dihydrofolate reductase-thymidylate synthase) which assembles into a functional 140-kDa homodimer. In mammals, the two enzymes are smaller distinct molecules encoded on different genes. A 27-kDa amino domain of malarial DHFR-TS is sufficient to provide DHFR activity, but the structural requirements for TS function have not been established. Although the 3'-end of DHFR-TS has high homology to TS sequences from other species, expression of this protein fragment failed to yield active TS enzyme, and it failed to complement TS(-) Escherichia coli. Unexpectedly, even partial 5'-deletion of full-length DHFR-TS gene abolished TS function on the 3'-end. Thus, it was hypothesized that the amino end of the bifunctional parasite protein plays an important role in TS function. When the 27-kDa amino domain (DHFR) was provided in trans, a previously inactive 40-kDa carboxyl-domain from malarial DHFR-TS regained its TS function. Physical characterization of the "split enzymes" revealed that the 27- and the 40-kDa fragments of DHFR-TS had reassembled into a 140-kDa hybrid complex. Thus, in malarial DHFR-TS, there are physical interactions between the DHFR domain and the TS domain, and these interactions are necessary to obtain a catalytically active TS. Interference with these essential protein-protein interactions could lead to new selective strategies to treat malaria resistant to traditional DHFR-TS inhibitors.

Animals↗

PubMed1999

Genome sequence of the radioresistant bacterium Deinococcus radiodurans R1.

The complete genome sequence of the radiation-resistant bacterium Deinococcus radiodurans R1 is composed of two chromosomes (2,648,638 and 412,348 base pairs), a megaplasmid (177,466 base pairs), and a small plasmid (45,704 base pairs), yielding a total genome of 3,284, 156 base pairs. Multiple components distributed on the chromosomes and megaplasmid that contribute to the ability of D. radiodurans to survive under conditions of starvation, oxidative stress, and high amounts of DNA damage were identified. Deinococcus radiodurans represents an organism in which all systems for DNA repair, DNA damage export, desiccation and starvation recovery, and genetic redundancy are present in one cell.

Bacterial Proteins↗

PubMed1999

ESR evidence of the photogeneration of free radicals (GDHB-, O2-) and singlet oxygen ((1)O2) by 15-deacetyl-13-glycine-substituted hypocrellin B.

15-Deacetyl-13-glycine-substituted hypocrellin B (GDHB) is a new type of hypocrellin derivative with an enhanced red absorption longer than 600 nm and water solubility. Visible light (> 470 nm) irradiation of an anaerobic aqueous solution of GDHB, the formation of GDHB*- was detected by an ESR method in the absence or presence of electron donor. When exposed to oxygen, superoxide anion radical and singlet oxygen were formed. The superoxide anion radical was generated by GDHB*- via electron transfer to oxygen and this process was significantly enhanced by the presence of electron donors. Singlet oxygen ((1)O2) was also formed in the photosensitization of GDHB in aerobic solution and 1,4-diazabicyclo [2,2,2] octane (DABCO), sodium azide (NaN3) and histidine inhibited the generation of (1)O2. A 9,10-diphenyl antracene (DPA)-bleaching method was used to determine the quantum yield of (1)O2 generated from GDHB photosensitization. The (1)O2 quantum yield was estimated to be 0.65. With the depletion of oxygen, the accumulation of GDHB*- would replace that of (1)O2. Evidence accumulated that the photodynamic action of GDHB may proceed via both type I and type II mechanisms and that a type II mechanism will be transformed into a type I mechanism as oxygen gets depleted.

Anions↗

PubMed1999

[Effect of dengue virus infection on the production of ET-1 and PGI2 by human vascular endothelial cells].

OBJECTIVE: To study the effect of dengue virus infection on the production of endothelin 1(ET-1) and prostacyclin 2(PGI2) by human umbilical cord vein endothelial cells (HUVECs). METHODS: HUVECs were infected by dengue-2 virus (DV-2), the culture supernatants were collected at 4, 24, 48, 72 and 96 hours postinfection, and the levels of ET-1 and PGI2 were measured by radio-immunoassay. RESULTS: The results showed that inhibition of production of ET-1 and PGI2 was induced by dengue virus infection in HUVECs. Marked inhibition of ET-1 and PGI2 production was observed as early as 4 h postinfection and the inhibitory effect continued until 96 h postinfection. Significant differences were shown between the ET-1 concentration of the virus-infected and non-infected cells. Nevertheless, the inhibitory effect of dengue virus infection on the production of PGI2 gradually decreased and the PGI2 concentration reverted to normal level at 96 h postinfection. No significant difference between the PGI2 concentration of the virus-infected and non-infected cells was seem. CONCLUSION: The present study suggests that dengue virus infection of vascular endothelial cells could affect their normal functions of secretion of vasoactive substances, resulting in increased vascular permeability and impairment of homostasis and blood coagulation. Therefore, functional impairment of vascular endothelial cells induced by dengue virus might be an important aspect in the pathogenesis of DHF/DSS.

Cells, Cultured↗

PubMed1999

Saccharide-RNA recognition in a complex formed between neomycin B and an RNA aptamer.

BACKGROUND: Aminoglycoside antibiotics can target RNA folds with micromolar affinity and inhibit biological processes ranging from protein biosynthesis to ribozyme action and viral replication. Specific features of aminoglycoside antibiotic-RNA recognition have been probed using chemical, biochemical, spectroscopic and computational approaches on both natural RNA targets and RNA aptamers identified through in vitro selection. Our previous studies on tobramycin-RNA aptamer complexes are extended to neomycin B bound to its selected RNA aptamer with 100 nM affinity. RESULTS: The neamine moiety (rings I and II) of neomycin B is sandwiched between the major groove floor of a 'zippered-up' G.U mismatch aligned segment and a looped-out purine base that flaps over the bound antibiotic. Specific intermolecular hydrogen bonds are observed between the charged amines of neomycin B and base mismatch edges and backbone phosphates. These interactions anchor 2-deoxystreptamine ring I and pyranose ring II within the RNA-binding pocket. CONCLUSIONS: The RNA aptamer complexes with tobramycin and neomycin B utilize common architectural principles to generate RNA-binding pockets for the bound aminoglycoside antibiotics. In each case, the 2-deoxystreptamine ring I and an attached pyranose ring are encapsulated within the major groove binding pocket, which is lined with mismatch pairs. The bound antibiotic within the pocket is capped over by a looped-out base and anchored in place through intermolecular hydrogen bonds involving charged amine groups of the antibiotic.

Anti-Bacterial Agents↗

PubMed1999

Selective killing of transformed cells by cyclin/cyclin-dependent kinase 2 antagonists.

Recent studies identified a short peptide motif that serves as a docking site for cyclin/cyclin-dependent kinase (cdk) 2 complexes. Peptides containing this motif block the phosphorylation of substrates by cyclin A/cdk2 or cyclin E/cdk2. Here we report that cell membrane-permeable forms of such peptides preferentially induced transformed cells to undergo apoptosis relative to nontransformed cells. Deregulation of E2F family transcription factors is a common event during transformation and was sufficient to sensitize cells to the cyclin/cdk2 inhibitory peptides. These results suggest that deregulation of E2F and inhibition of cdk2 are synthetically lethal and provide a rationale for the development of cdk2 antagonists as antineoplastic agents.

Amino Acid Sequence↗