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Biomedical subjects

C Bai

Publications and source records attributed to C Bai.

At least 55 records · Page 3Linked to original sources
PubMed1999

Lung fluid transport in aquaporin-1 and aquaporin-4 knockout mice.

The mammalian lung expresses water channel aquaporin-1 (AQP1) in microvascular endothelia and aquaporin-4 (AQP4) in airway epithelia. To test whether these water channels facilitate fluid movement between airspace, interstitial, and capillary compartments, we measured passive and active fluid transport in AQP1 and AQP4 knockout mice. Airspace-capillary osmotic water permeability (Pf) was measured in isolated perfused lungs by a pleural surface fluorescence method. Pf was remarkably reduced in AQP1 (-/-) mice (measured in cm/s x 0.001, SE, n = 5-10: 17 +/- 2 [+/+]; 6.6 +/- 0.6 AQP1 [+/-]; 1.7 +/- 0.3 AQP1 [-/-]; 12 +/- 1 AQP4 [-/-]). Microvascular endothelial water permeability, measured by a related pleural surface fluorescence method in which the airspace was filled with inert perfluorocarbon, was reduced more than 10-fold in AQP1 (-/-) vs. (+/+) mice. Hydrostatically induced lung interstitial and alveolar edema was measured by a gravimetric method and by direct measurement of extravascular lung water. Both approaches indicated a more than twofold reduction in lung water accumulation in AQP1 (-/-) vs. (+/+) mice in response to a 5- to 10-cm H2O increase in pulmonary artery pressure for five minutes. Active, near-isosmolar alveolar fluid absorption (Jv) was measured in in situ perfused lungs using 125I-albumin as an airspace fluid volume marker. Jv (measured in percent fluid uptake at 30 min, n = 5) in (+/+) mice was 6.0 +/- 0.6 (37 degrees C), increased to 16 +/- 1 by beta-agonists, and inhibited to less than 2.0 by amiloride, ouabain, or cooling to 23 degrees C. Jv (with isoproterenol) was not affected by aquaporin deletion (18.9 +/- 2.2 [+/+]; 16.4 +/- 1.5 AQP1 [-/-]; 16.3 +/- 1.7 AQP4 [-/-]). These results indicate that osmotically driven water transport across microvessels in adult lung occurs by a transcellular route through AQP1 water channels and that the microvascular endothelium is a significant barrier for airspace-capillary osmotic water transport. AQP1 facilitates hydrostatically driven lung edema but is not required for active near-isosmolar absorption of alveolar fluid.

Animals↗
PubMed1999

[Clinical analysis of 12 cases with venous thromboembolism during pregnancy and puerperium].

OBJECTIVE: To study the incidence, cause and clinical manifestation of venous thromboembolism during pregnancy and puerperium, and its diagnosis and treatment. METHODS: 12 cases of venous thromboembolism admitted in our hospital from 1984-1997 were analysed retrospectively. The plasma protein C, protein S and antithrombin III activities were measured in 4 of the cases and activated protein C resistance (APC-R) were assayed by activated partial thrombinplastin time (APIT) in the presence and absence of APC (APC-APIT) and FV Leiden gene mutation were analysed by PCR restriction fragment length polymorphisms (RFLP) methods as well. RESULTS: Four cases occurred before delivery and 8 postpartum. Two cases complicated by pulmonary thromboembolism, and of them 1 died. APC-R(+), reduced activity of antithrombin-III and protein S each were found in 3 separate cases. No FV Leiden gene mutation was found in the 4 cases. CONCLUSIONS: The formation of venous thromboembolism during pregnancy and puerperium is highly associated with the deficiency of anticoagulant proteins. Anticoagulation is recommended in the high risk women of thromboembolism.

Adult↗
PubMed1999

[Study on thrombomodulin and plasminogen activator inhibitor type-1 in patients of pregnancy induced hypertension].

OBJECTIVE: To study the circulating levels of Thrombomodulin (TM) and Plasminogen activator inhibitor type-1 (PAI-1) in women with pregnancy induced hypertension (PIH) and normal pregnant women. METHODS: Blood samples were withdrawn from 73 pregnant women, In which 25 mild PIH, 26 moderate PIH, 22 severe PIH were divided into study group, and 24 normotensive healthy pregnant women in their third trimester were control group. The determination of TM was measured by ELISA and PAI-1 by Colorimetric Assay methods. RESULTS: Circulation levels of TM and PAI-1 were increased with increasing severity of the PIH. There were no significant differences between groups of mild PIH and normal pregnancy (TM 45.69 +/- 15.15 micrograms/L and 40.14 +/- 15.82 micrograms/L, PAI-1 22.06 +/- 12.13 kU/L and 18.40 +/- 9.78 kU/L respectively). The parameters significantly increased in moderate (TM 52.76 +/- 13.91 micrograms/L, PAI-1 25.77 +/- 9.45 kU/L) and severe PIH (TM 64.84 +/- 15.16 micrograms/L, PAI-1 30.79 +/- 11.64 kU/L) groups. CONCLUSIONS: These results demonstrate that the endothelial cell damage and its functional disturbance play a very important role in the etiology of PIH. TM and PAI-1 may serve as clinical markers for the assessment of endothelial damage in PIH.

Adult↗
PubMed1999

[Factor V Leiden and PTG20210A gene mutation in patients with venous thrombosis and healthy blood donors].

OBJECTIVE: To evaluate the incidence of factor V Leiden and prothrombin gene G20210A mutation in patients with venous thrombosis and healthy volunteers. METHODS: Factor V Leiden and prothrombin gene G20210A mutation were analysed in 97 cases of venous thrombosis and 100 healthy volunteers with the methods of one-step PCR-RFLP. RESULTS: PCR products for the factor V gene (175 bp) and for the prothrombin gene (118 bp) were identified to 157 bp and 98 bp fragments by electrophoresis after Taq I treatment. No factor V Leiden and prothrombin gene G20210A mutation were found in either group. CONCLUSION: The low incidence of factor V Leiden and prothrombin gene G20210A mutation suggest that they are not the major genetic risk factors for thrombophilia in the Chinese.

Adolescent↗
PubMed1999

The diagnostic value of total respiratory impedance by impulse oscillometry in chronic obstructive lung disease.

OBJECTIVE: To investigate the diagnostic significance of total respiratory impedance for chronic obstructive lung disease. METHODS: The impedance of respiratory system was measured by impulse oscillometry method and compared with parameter values of routine pulmonary function in 57 patients with chronic obstructive pulmonary disease (COPD). RESULTS: It significantly increased in viscous resistance ranging from 5 Hz and 35 Hz and resonant frequency in COPD group than that in healthy group. Reactance from 5 Hz and 35 Hz in COPD group was marked lower than that in healthy group. There were marked frequency dependence of viscous resistance and reactance in COPD patients. Resonant frequency was markedly and negatively correlated with parameters of pulmonary ventilation indices; X5 was positively correlated with parameters of pulmonary ventilation indices. But no statistical correlation was showed between R20 and parameters of pulmonary ventilation indices. Correlation was found between resonance frequency and FEV1, resonance frequency and Vmax. The correlation coefficient values were -0.671 and -0.666 respectively. The sensitivity of resonant frequency, R5 and X5 for diagnosing COPD were 94.74%, 59.65% and 54.38%, respectively. The specificity of them were 86.66%, 96.66% and 90%, respectively. CONCLUSIONS: Resonant frequency was the most sensitive index in the parameters measured by IOS for diagnosing COPD. Since impedance measurement was a non-invasive method and only passive co-operation of the patient was needed. This technique could therefore be applied in COPD patients with acute attack for dynamic examination.

Aged↗
PubMed1999

[Human motion analysis system based on common video-camera].

A new human motion analysis system based on common video-camera is introduced in this paper. The image processing technique is used to recognize and track anatomic landmarks, which makes data processing more quickly and accurately. The system is cost-effective and can be easily operated because the common video-cameras instead of special instruments are used. Furthermore, the system can also be used for detection and analysis of other low-speed moving objects.

Algorithms↗
PubMed1998

[Relationship between genotype of angiotensin converting enzyme gene and left ventricular hypertrophy in Chinese hypertensives].

OBJECTIVE: To search into the relationship between genotype of angiotensin-converting enzyme (ACE) gene and left ventricular hypertrophy(LVH) in Chinese hypertensives. METHODS: ACE genotyping with polymerase chain reaction (PCR) was performed in 33 unrelated hypertensives with LVH, 55 hypertensives without cardio-cerebrovascular diseases and 62 healthy controls. RESULTS: The frequencies of DD genotype (0.394) and deletion allele (0.606) among hypertensives with LVH were significantly higher than those (0.129 and 0.387) among controls and those (0.128 and 0.400) among hypertensives without cardio-cerebrovascular diseases. CONCLUSION: A deletion polymorphism of ACE gene probably increases the risk for left ventricular hypertrophy in Chinese hypertensives.

Adult↗
PubMed1998

A convenient method of aligning large DNA molecules on bare mica surfaces for atomic force microscopy.

Large DNA molecules remain difficult to be imaged by atomic force microscopy (AFM) because of the tendency of aggregation. A method is described to align long DNA fibers in a single direction on unmodified mica to facilitate AFM studies. The clear background, minimal overstretching, high reproducibility and convenience of this aligning procedure make it useful for physical mapping of genome regions and the studies of DNA-protein complexes.

Aluminum Silicates↗
PubMed1998

The observation of the local ordering characteristics of spermidine-condensed DNA: atomic force microscopy and polarizing microscopy studies.

Condensation of DNA by multivalent cations can provide useful insights into the physical factors governing the folding and packaging of DNA in vivo. In this work, local ordered structures of spermidine-DNA complexes prepared from different DNA concentrations have been examined by using atomic force microscopy (AFM) and polarizing microscopy (PM). Two types (I and II) of DNA condensates, significantly different in sizes, were observed. It was found that for extremely dilute solutions (DNA concentrations around 1 ng/microl or below), the DNA molecules would collapse into toroidal structures with a volume equivalent to a single lambda-DNA (type I). In relatively dilute solutions (DNA concentrations between 1 and 10 ng/microll), a significantly larger structure of multimolecular toroids (circular and elliptical, type II) were formed, which were constructed by many fine particles. Measurements show that the average diameter of these fine particles was similar to the outer diameter of the monomolecular toroids observed in extremely dilute solutions, and the thickness of the multimolecular toroids had a distribution of multi-layers with height increments of 11 nm, indicating that the multimolecular toroidal structures have lamellar characteristics. Moreover, by enriching the DNA-spermidine complexes in very diluted solution, branch-like structures constructed by subunits were observed by using AFM. The analysis of the pellets in polarizing microscopy reveals a liquid-crystal-like pattern. These observations suggest that DNA-spermidine condensation could have multiple stages, which are very sensitive to the DNA and spermidine concentrations.

Bacteriophage lambda↗
PubMed1998

Drosophila clipper/CPSF 30K is a post-transcriptionally regulated nuclear protein that binds RNA containing GC clusters.

An essential component of the mammalian pre-mRNA 3'-end processing machinery is a multimeric protein complex known as cleavage and polyadenylation specificity factor (CPSF). The Drosophila melanogaster gene, clipper ( clp ), encodes a homolog of the CPSF 30K subunit. We have shown previously that CLP possesses N-terminal endoribonucleolytic activity and that the relative expression of its mRNA fluctuates during fly development. In the present study, we report that CLP's C-terminus, containing two CCHC zinc knuckles, confers a binding preference for RNAs that contain G- and/or C-rich clusters. We also show, for the first time, that a member of the highly conserved CPSF 30K family is a nuclear and developmentally regulated protein. Though clp transcripts are detectable throughout embryogenesis, CLP protein is not present. We demonstrate that post-transcriptional regulation of clp mRNA in the embryo occurs by a process that does not involve poly(A) tail length shortening. Thus, a key component of the pre-mRNA 3'-end processing machinery is subject to post-transcriptional regulation during development. These results support the existence of a distinct mechanism controlling eukaryotic gene expression through the regulated processing of pre-mRNAs in the nucleus.

Amino Acid Sequence↗
PubMed1998

Uncoupling protein-3: a muscle-specific gene upregulated by leptin in ob/ob mice.

We identified and partially characterized another member of the uncoupling protein termed UCP3. Human and mouse UCP3 protein sequences are 86% identical to each other, and 73% and 59% identical to UCP2 and UCP1, respectively. Expression of human UCP3 in yeast resulted in a drastic decrease of mitochondria membrane potential. Northern analysis showed that UCP3 was highly expressed in skeletal muscle in human, rat, and mouse. Mapping of UCP3 placed it to the same chromosomal region of UCP2 in both human and mouse, a region that is linked to obesity and hyperinsulinemia. Furthermore, adenovirus-mediated leptin expression in obese ob/ob mice led to increased expression of UCP3 in skeletal muscle. The data indicate that UCP3 encodes a muscle-specific uncoupling protein that may play an important role in the regulation of energy expenditure and development of obesity.

Adenoviridae↗
PubMed1998

S-[(1 and 2)-phenyl-2-hydroxyethyl]cysteine-induced alterations in renal mitochondrial function in male Fischer-344 rats.

Previous studies from our laboratory have shown that mitochondrial dysfunction may be an important early event in S-[(1 and 2)-phenyl-2-hydroxyethyl]cysteine (PHEC)-induced cytotoxicity in isolated rat renal proximal tubules. The present study has therefore examined in more detail PHEC-induced mitochondrial dysfunction, both in vivo and in vitro, using isolated renal cortical mitochondria. Renal cortical mitochondria isolated from PHEC-treated rats in vivo showed depressed effects on the mitochondrial respiration and oxidative phosphorylation in both a dose (0, 250, and 500 micromol/kg iv)- and time (0-24 h)-dependent manner in the presence of both succinate (Site 2) and malate plus alpha-ketoglutarate (Site 1) as respiratory substrates, with initial significant depression occurring as early as 4 h following treatment with 500 micromol PHEC/kg. Similar mitochondrial dysfunctions were observed in vitro in concentration- and time-dependent manners with both respiratory substrates. PHEC also caused a marked dose-dependent inhibition of mitochondrial succinate dehydrogenase and NADH cytochrome c reductase activities both in vivo and in vitro, with initial inhibition occurring as early as 4 h after in vivo administration and 45 min after exposure to PHEC in vitro, while the NADH dehydrogenase activity was not considerably inhibited. The mitochondrial ATPase activity was significantly decreased 4 and 24 h following treatment with PHEC (500 micromol/kg). These results suggest that PHEC exerts its inhibitory effect on the mitochondrial respiration and oxidative phosphorylation through the action on the mitochondrial electron transport chain. PHEC significantly reduced the activity of adenine nucleotide translocase as well as the net uptake of substrates by mitochondria without affecting their efflux within 2-4 h after its injection (500 micromol/kg). On the other hand, significant renal damage, as assessed by morphological study, appeared as early as 24 h following such treatment. The observation of similar effects after both in vivo and in vitro exposures may suggest that the effect on mitochondria may have a pathogenic role in PHEC-induced renal injury in rats. PHEC produces mitochondrial toxicity that results from an inactivation of mitochondrial anionic substrate transporters as well as from an inhibition of activities of adenine nucleotide translocase and dehydrogenases.

Animals↗
PubMed1998

A mouse model to test the in vivo efficacy of chemical chaperones.

In vitro studies in transfected cells have indicated that chemical chaperones including glycerol (0.5-1.2 M) and trimethylamine oxide (TMAO, 50-100 mM) can correct defective trafficking of some proteins, including deltaF508 CFTR in cystic fibrosis and AQP2 mutants in nephrogenic diabetes insipidus. To develop a mouse model to test the efficacy of chemical chaperones in vivo, glycerol and TMAO were administered by intraperitoneal (i.p.), subcutaneous (s.c.), and oral routes. Glycerol and TMAO assays that utilized 1-5 microL of tail vein blood were developed. Administration by the i.p. and s.c. routes gave maximum serum glycerol concentrations of approximately 100 mM, levels that were well below the effective in vitro concentrations. Single i.p. or s.c. doses of TMAO (7 g/kg, 8% solution in water) resulted in serum [TMAO] greater than 50 mM, with a long half-life (t1/2 approximately equal to 18-21 h). Sustained high serum and tissue [TMAO] > 52 mM for 3 days was achieved by s.c. administration of TMAO (7 g/kg) in water every 8 h. Although approximately 50% of the mice died with this multiple-dose regimen, the remaining mice had nearly normal liver, renal, and pancreatic function. A lower dose of TMAO (5 g/kg) given by the s.c. route every 8 h resulted in serum [TMAO] concentration of 22 mM, a level that was well tolerated by all mice for 72 h. These mice also had high [TMAO] in urine, 400 mM. These results demonstrate that potentially therapeutic concentrations of TMAO can be sustained in mice in vivo, permitting the testing of chemical chaperones in transgenic mouse models of diseases caused by defective protein trafficking.

Animals↗
PubMed1998

Effect of selective substitution of 5-bromocytosine on conformation of DNA triple helices.

Three triplex DNAs containing 5-bromocytosine[BrC] were studied by vibrational spectroscopy and molecular modelling. Firstly, three oligodeoxypyrimidines of 5'-(TC)3-T4-(BrCT)3 [CBrC], 5'-(TBrC)3-T4-(CT)3 [BrCC] and 5'-(TBrC)3-T4-(BrCT)3 [BrCBrC] were synthesized and then reacted with an oligodeoxypurine of 5'-(AG)3 at pH=4.5 in phosphate buffer respectively to form three comparative hairpin triplex named CY,YC and YY. The results of FT-Raman and IR revealed that YY is almost in A-like form, CY and YC are combinations of A-like form and B-like form, but A-form dominates in CY while B-form is equivalent as A-form in YC. The result is consistent with the theoretical analysis.

Cytosine↗
PubMed1998

[Relationship between plasma endothelin, nitric oxide, calcitonin gene-related peptide levels and pulmonary hemodynamics in patients with chronic cor pulmonale].

OBJECTIVE: To explore the relationship between plasma endothlin-1 (ET-1), nitric oxide (NO), calcitonin gene-related peptide (CGRP) levels and hypoxic pulmonary hypertension. METHOD: Cardiac catheterization was performed in 55 cases of chronic cor pulmonale to monitor the changes of their hemodynamic indices and to determine the levels of pulmonary arterial plasma ET-1, NO and CGRP. RESULT: The plasma ET-1 level of patients with pulmonary hypertension (Group A) was significantly higher than that of patients without pulmonary hypertension (Group B) and controls. The plasma NO level of group A was significantly lower than that of Group B and controls. The plasma CGRP level of ET-1 had a significantly negative correlation with PaO2 and positive correlation with pulmonary arterial pressure. The levels of NO and CGRP had significantly positive correlation with PaO2 and negative correlation with pulmonary arterial pressure. After 60-min oxygenation with 30% oxygen inhalation, the level of ET-1 decreased remarkably, but the levels of NO and CGRP went up notably. CONCLUSION: These results demonstrate that hypoxia affects plasma ET-1, NO, CGRP levels in patients with chronic cor pulmonale. ET-1, NO, CGRP play synergistic roles in regulation of pulmonary arterial pressure.

Adult↗
PubMed1998

[The growth inhibition of anti-EGF receptor monoclonal antibody to human lung adenocarcinoma cells].

OBJECTIVE: Epidermal growth factor (EGF) and its receptor play a critical role in the growth and regulation of many type of malignant cell. The high level of expression of the EGFR on normal cell lung cancer(NSCLC) and the important role of EGFR in signal transduction make it potentially an excellent target for antibody directed therapy. The purpose of this study was to evaluate the anti-tumor effects of anti-EGFR monoclonal antibody on lung carcinoma cells. METHOD: Preparation of hybrid cell producing anti-EGFR monoclonal antibody using EGF receptors partially purified from A431 cells as immunogen. The effect of anti-EGFR monoclonal antibody to human lung cells was investigated in vitro. RESULT: The anti-EGFR monoclonal antibody was shown to inhibit the proliferation of human lung adenocarcinoma cells in vitro, but no growth-inhibitory effect was observed in the human small cell lung cancer cells. The concentration, 15 ug/ml, of anti-EGFR antibody could inhibit growth rate by 94% and 88% for human lung adenocarcinoma cell lines SPC A-1 and A549, respectively. CONCLUSION: Our initial results indicate that the anti-EGF receptor monoclonal antibody may be potentially useful for the biotherapy of lung adenocarcinoma.

Adenocarcinoma↗
PubMed1998

Iterative reconstruction of fluorine-18 SPECT using geometric point response correction.

UNLABELLED: This article demonstrates resolution recovery in 18F SPECT image reconstruction by using an iterative algorithm that corrects for the system geometric response. METHODS: Patient and phantom studies were performed using a Picker PRISM 3000 three-detector SPECT system (Picker International, Inc., Cleveland, OH) to image 18F with 511 keV collimators. A measured point response function of the imaging system was used in an iterative reconstruction algorithm in which the projector and backprojector modeled the system point response function by using an efficient layer-by-layer blurring technique. The blurring function was a five-element kernel in the shape of a cross. The iterative reconstruction algorithm was an ordered-subset maximum-likelihood expectation maximization algorithm. RESULTS: The iterative reconstruction algorithm with geometric response correction showed an improvement in resolution over the filtered backprojection reconstruction and the iterative reconstruction without correction. CONCLUSION: The proposed iterative reconstruction algorithm with geometric response correction is efficient and effective with significant resolution recovery.

Aged↗