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Biomedical subjects

C X Huang

Publications and source records attributed to C X Huang.

At least 19 recordsLinked to original sources
PubMed2006

Troponin T measurement can predict persistent left ventricular dysfunction in peripartum cardiomyopathy.

OBJECTIVE: To determine whether measurement of cardiac troponin T (cTnT) concentration in newly diagnosed peripartum cardiomyopathy (PPCM) can be used to predict persistent left ventricular dysfunction after a 6-month follow-up. PATIENTS AND METHODS: This was a prospective, multiple-centre clinical trial that studied 106 patients with newly diagnosed PPCM surviving over 6 months. cTnT concentration was measured within 2 weeks of the onset of PPCM. RESULTS: Serum cTnT concentration was negatively correlated with left ventricular ejection fraction (LVEF) at follow-up (LVEF, r = -0.518, p = 0.0001). Analysis by receiver operator characteristic curve yielded an area under the curve of 0.764 (95% CI 0.669 to 0.860, p = 0.0001, vs null hypothesis value 0.5) for cTnT, and a cTnT concentration cut off of >0.04 ng/ml, predicting persistent left ventricular dysfunction with a sensitivity of 54.9% and a specificity of 90.9%. Among 106 recruited patients, there were 33 patients with cTnT concentrations >0.04 ng/ml and 73 patients with cTnT concentrations < or =0.04 ng/ml. After a 6-month follow-up, there was significantly smaller LVEF (35.42% (13.04% vs 50.16% (10.48%, p = 0.0001) and more persistent left ventricular dysfunction (84.8% vs 31.5%, OR = 12.17 (95% CI 4.17 to 35.57), p = 0.001) in patients with cTnT >0.04 ng/ml than in patients with cTnT < or =0.04 ng/ml. CONCLUSION: Serum cTnT concentration measured within 2 weeks of the onset of PPCM was correlated negatively with LVEF at follow-up. This marker offers a simple, quick, inexpensive, non-invasive method for predicting a persistent LVEF of < or =50%. A cTnT concentration of >0.04 ng/ml predicted persistent left ventricular dysfunction with a sensitivity of 54.9% and a specificity of 90.9%.

Adult↗
PubMed2006

Freeze/thaw-induced embolism depends on nadir temperature: the heterogeneous hydration hypothesis.

Freeze/thaw-induced embolism was studied in leaves of field-grown snow gum (Eucalyptus pauciflora) subject to frequent morning frosts. Juvenile trees were grown in buried pots, brought to the laboratory at different stages of acclimation and subjected to simulated frost-freezes (at 2 degrees C h(-1)) to nadir temperatures of -3 or -6 degrees C, which snow gums commonly experience. Frost-frozen and subsequently thawed leaves were cryo-fixed to preserve the distribution of water and were then examined by cryo-scanning electron microscopy. No embolisms were found in leaves frozen to -3 degrees C and thawed. In contrast, 34% of vessels were embolized in thawed leaves that had been frozen to -6 degrees C. This difference was seen also in the extent of extracellular ice blocks in the mid-vein expansion zones in leaves frozen to -3 and -6 degrees C, which occupied 3 and 14% of the mid-vein area, respectively. While the proportion of embolism depended on nadir temperature, it was independent of season (and hence of acclimation state). From the observation that increased embolism at lower nadir temperature was related to the freeze-induced redistribution of water, we hypothesize that the dehydration of cell walls and cells caused by the redistribution exerts sufficient tension on xylem water to induce cavitation on thawing.

Adaptation, Physiological↗
PubMed2006

Leaf water content and palisade cell size.

The palisade cell sizes in leaves of Eucalyptus pauciflora were estimated in paradermal sections of cryo-fixed leaves imaged in the cryo-scanning electron microscope, as a quantity called the cell area fraction (CAF). Cell sizes were measured in detached leaves as a function of leaf water content, in intact leaves in the field during a day"s transpiration as a function of balance pressure of adjacent leaves, and on leaf disks equilibrated with air of relative humidities from 100 to 58%. Values of CAF ranged from 0.82 at saturation to approx. 0.3 in leaves dried to a relative water content (RWC) of 0.5, and in the field to approx. 0.58 at 15 bar (1.5 MPa) balance pressure. At a CAF of 0.58, the moisture content of the cell walls is in equilibrium with air at 90% relative humidity, which is the estimated relative humidity in the intercellular spaces. It is shown that at this moisture content, the cell walls could be exerting a pressure of approx. 50 bar on the cell contents.

Cell Size↗
PubMed2005

Comparison of rate control and rhythm control in patients with atrial fibrillation after percutaneous mitral balloon valvotomy: a randomised controlled study.

OBJECTIVE: To compare rate control and rhythm control strategies in patients with atrial fibrillation (AF) after percutaneous mitral balloon valvotomy (PMV). METHODS: 183 patients with AF after successful PMV, with AF duration <or= 12 months and post-PMV left atrial (LA) size <or= 45 mm, were studied in a prospective, randomised trial. The primary end point was improvement in AF-related symptoms. Secondary study end points were 6 min walk tests, quality of life (QOL), normalisation of LA size, number of hospital admissions and duration of hospital stay. RESULTS: Over one year, 2% patients in the rate control group had sinus rhythm, as compared with 96% of patients in the rhythm control group (p < 0.001). A greater proportion of patients reported improvement in symptoms in the rhythm control group than in the rate control group (p < 0.0001 at every visit time). Walking distance in a 6 min walk test, QOL and LA size normalisation were better in the rhythm control group than in the rate control group. The strategy of rhythm control was associated with similar numbers of hospital admissions but with longer duration of hospital admissions. Drug-related side effect did not differ between the rate control and rhythm control groups. During the follow-up period, no patients in either group had embolic or transitory ischaemic neurological events. CONCLUSIONS: In patients with AF after PMV, AF duration <or= 12 months and post-PMV LA size <or= 45 mm, sinus rhythm was easy and safe to achieve and maintain. Moreover, patients benefited from restoration and maintenance of sinus rhythm in terms of improved AF-related symptoms, 6 min walk tests and QOL, and of LA size normalisation. Rhythm control should therefore be considered as the preferred initial therapy for this group of patients. The optimal strategy to treat AF after PMV should be individualised.

Adult↗
PubMed2004

The management of extracellular ice by petioles of frost-resistant herbaceous plants.

BACKGROUND AND AIMS: Some frost-tolerant herbaceous plants droop and wilt during frost events and recover turgor and posture on thawing. It has long been known that when plant tissues freeze, extracellular ice forms. Distributions of ice and water in frost-frozen and recovered petioles of Trifolium repens and Escholschzia californica were visualized. METHODS: Petioles of intact plants were cryo-fixed, planed to smooth transverse faces, and examined in a cryo-SEM. KEY RESULTS: With frost-freezing, parenchyma tissues shrank to approx. one-third of their natural volume with marked cytorrhysis of the cells, and massive blocks of extracellular icicles grew under the epidermis (poppy) or epidermis and subepidermis (clover), leaving these layers intact but widely separated from the parenchyma except at specially structured anchorages overlying vascular bundles. On thawing, the extracellular ice was reabsorbed by the expanding parenchyma, and surface tissues again contacted the internal tissues at weak junctions (termed faults). These movements of water into and from the fault zones occurred repeatedly at each frost/thaw event, and are interpreted to explain the turgor changes that led to wilting and recovery. Ice accumulations at tri-cellular junctions with intercellular spaces distended these spaces into large cylinders, especially large in clover. Xylem vessels of frozen petioles were nearly all free of gas; in thawed petioles up to 20 % of vessels were gas-filled. CONCLUSIONS: The occurrence of faults and anchorages may be expected to be widespread in frost-tolerant herbaceous plants, as a strategy accommodating extracellular ice deposits which prevent intracellular freezing and consequent membrane disruption, as well as preventing gross structural damage to the organs. The developmental processes that lead to this differentiation of separation of sheets of cells firmly cemented at determined regions at their edges, and their physiological consequences, will repay detailed investigation.

Cryoelectron Microscopy↗
PubMed2004

Additive effects of combined valsartan and spironolactone on cardiac aldosterone escape in spontaneously hypertensive rats.

The additive effects of combined valsartan and spironolactone on plasma and cardiac aldosterone escape were evaluated in spontaneously hypertensive rats (SHRs). Twenty-four SHRs were treated with valsartan (30 mg/kg body weight per day), spironolactone (20 mg/kg body weight per day) and a combination of both for 4 months. Blood was collected and plasma aldosterone (PA) was estimated with radioimmunoassay (RIA). Ex vivo heart perfusion was performed, the ex vivo cardiac aldosterone (EXCA) was assessed by RIA after high-performance liquid chromatography separation. PA and EXCA were significantly decreased after one month but increased after 4 months in valsartan administration group. The combined valsartan and spironolactone therapy normalized cardiac aldosterone levels. This study provides the first evidence that the long-term treatment with Angiotensin II type 1 receptor antagonist (AT1A) induces local aldosterone escape in cardiovascular tissue, whereas the combined AT1A and spironolactone therapy inhibits the escape in hypertensive rats.

Aldosterone↗
PubMed2004

In vitro mutagenesis of Xanthomonas campestris alpha-amylase gene by partially replacing deoxythymidine triphosphate with 5-bromo-2'-deoxyuridine-5'-triphosphate using a PCR technique.

Three mutants of the wild type alpha-amylase gene from Xanthomonas campestris pv. campestris 8004 were obtained using a PCR technique in which deoxythymidine triphosphate (dTTP) was partially replaced by 5-bromo-2'-deoxyuridine-5'-triphosphate (BrdUTP), at an optimal dTTP:BrdUTP ratio of 1000:1. Of thre three mutants that were obtained and which were sequenced, one mutant with 40 times higher activity than the wild type alpha-amylase gene product was obtained by using primary PCR products as a template for a second PCR reaction.

Cloning, Molecular↗
PubMed2002

Loss of expression of death-inducing signaling complex (DISC) components in lung cancer cell lines and the influence of MYC amplification.

We have previously reported that the key apoptosis related gene caspase 8 (CASP8) is frequently silenced in small cell lung cancer (SCLC) tumors and cell lines usually, but not always, by aberrant promoter methylation. Because CASP8 is a key component of the death-inducing signaling complex (DISC) when specific death receptors (including DR4, DR5, FAS) are activated by their specific ligands (TRAIL/FASL), we examined expression of the components of the DISC complex in lung cancer cell lines. MYC family members are frequently amplified (MYC+ve) in SCLC, and MYC is a potent inducer of apoptosis. We examined 34 SCLC lines (12 of which were MYC+ve) and 22 NSCLC lines. CASP8 gene expression was frequently lost (79%) at message and protein levels in SCLC but not in non-SCLC (NSCLC). MYC amplification was present in 45% of SCLC cell lines, which had lost CASP8 expression, but not in any of the CASP8 positive lines. The frequency of CASP8 loss was significantly higher in MYC+ve SCLC compared to MYC-ve SCLC or in NSCLC. Analyses of other DISC components showed significantly higher rates of loss of expression of CASP10, DR5, FAS and FASL in SCLC compared to NSCLC. The loss of expression of proapoptotic DISC components was significantly higher in MYC+ve SCLC cell lines and these lines were completely resistant to TRAIL. Expression of CASP10 (a caspase closely related to CASP8) was frequently absent at the protein level in both SCLC and NSCLC lines. Expression of c-FLIP (proteolytically inactive homolog of CASP8) was inversely related to expression of CASP8. Our major conclusions are: (a) The death receptor pathway is differently inactivated at multiple levels in lung cancer cell lines; and (b) MYC amplification in SCLC is associated with inactivation of most components of the DISC complex, with resistance to TRAIL and with expression of c-FLIP. These findings may have considerable clinical and therapeutic implications.

Carcinoma, Non-Small-Cell Lung↗
PubMed2001

[Expression of the neural cell adhesion molecule in human astrocytomas].

OBJECTIVE: To investigate the expression of the neural cell adhesion molecule (NCAM) in human astrocytomas, and evaluate the relationship between NCAM and proliferating cell nuclear antigen (PCNA). METHODS: Forty-eight astrocytomas were studied by SP method with monoclonal antibody against NCAM and PCNA proteins. RESULTS: All normal brain tissues expressed NCAM; NCAM expression was positive in Grade I-II glioma [95% (19/20)], Grade III glioma [38.9% (7/18)], Grade IV glioma [20% (2/10)] respectively. An inverse correlation was observed between the degree of NCAM expression and that of PCNA (r = -0.657, P < 0.05). CONCLUSION: NCAM is a down-regulated factor in the development of the malignancy of astrocytomas; and it is suggested that the reduced NCAM expression might be involved in the development of biological malignancy.

Astrocytoma↗
PubMed2001

[Growth inhibition of epidermal growth factor-stimulated human glioblastoma cells by nicardipine in vito].

OBJECTIVE: To study the growth effects of epidermal Growth Factor (EGF) and the calcium channel antagonist nicardipine (NC) on U251 MG, a human malignant glioma cell lime, which has high-affinity EGF receptors. METHODS: The growth effects of EGF and NC on U251 MG cultured in serum-free and serum-containing (10% fetal bovine serum, FBS) media respectively were observed by MTT colorimeritric analysis. RESULTS: (1) EGF significantly enhanced the growth of U251 MG in a dose-dependent manner in serum-free conditions. The near-maximal effect was obtained at 10 mg.ml-1. The addition of serum obscured this effect. (2) NC decreased U251 MG cells proliferation, especially in serum-containing media, and completely blocked the growth-stimulated effect of EGF. The combinated effects of EGF (10 ng.ml-1) and NC equaled those of NC alone. CONCLUSIONS: When serum is absent U251 MG cells showed a pronounced mitogenic response to EGF in a dosedependent manner, which approximated that achieved with 10% FBS. NC suppressed the growth of U251 MG cells and completely blocked the growth-stimulated effects of EGF, it can be used as an adjuvent therapy for human malignant gliomas.

Antineoplastic Agents↗
PubMed2001

Aberrant methylation of the adenomatous polyposis coli (APC) gene promoter 1A in breast and lung carcinomas.

The adenomatous polyposis coli (APC) gene is a tumor suppressor gene associated with both familial and sporadic cancer. Despite high rates of allelic loss in lung and breast cancers, point mutations of the APC gene are infrequent in these cancer types. Aberrant methylation of the APC promoter 1A occurs in some colorectal and gastric malignancies, and we investigated whether the same mechanism occurs in lung and breast cancers. The methylation status of the APC gene promoter 1A was analyzed in 77 breast, 50 small cell (SCLC), and 106 non-small cell (NSCLC) lung cancer tumors and cell lines and in 68 nonmalignant tissues by methylation-specific PCR. Expression of the APC promoter 1A transcript was examined in a subset of cell lines by reverse transcription-PCR, and loss of heterozygosity at the gene locus was analyzed by the use of 12 microsatellite and polymorphic markers. Statistical tests were two-sided. Promoter 1A was methylated in 34 of 77 breast cancer tumors and cell lines (44%), in 56 of 106 NSCLC tumors and cell lines (53%), in 13 of 50 SCLC cell lines (26%), and in 3 of 68 nonmalignant samples (4%). Most cell lines tested contained the unmethylated or methylated form exclusively. In 27 cell lines tested, there was complete concordance between promoter methylation and silencing of its transcript. Demethylation with 5-aza-2'-deoxycytidine treatment restored transcript 1A expression in all eight methylated cell lines tested. Loss of heterozygosity at the APC locus was observed in 85% of SCLCs, 83% of NSCLCs, and 63% of breast cancer cell lines. The frequency of methylation in breast cancers increased with tumor stage and size. In summary, aberrant methylation of the 1A promoter of the APC gene and loss of its specific transcript is frequently present in breast and NSCLC cancers and cell lines and, to a lesser extent, in SCLC cell lines. Our findings may be of biological and clinical importance.

Adenomatous Polyposis Coli Protein↗
PubMed2000

Modulation of the basal activity of phosphatidylinositol-3-kinase/protein kinase B signaling pathway in human hepatocarcinoma cells.

The modulation of GnT-V activity by signaling molecules in PI-3-K/PKB pathway in human hepatocarcinoma cell line 7721 was studied. GnT-V activity was determined after the transfection of sense or antisense cDNA of PKB into the cells, as well as the addition of activators, specific inhibitors, and the antibodies to the enzyme assay system or culture medium. It was found that the basal activity of GnT-V was up regulated by the sense and down regulated by the antisense cDNA of PKB transfected into 7721 cells. GnT-V was activated by PIP2, PIP3 or GTPgamma[S] added to the assay system, and the activation of PIP2 or GTPgamma[S] was abolished by LY2940002, a specific inhibitor of PI-3-K, but the activation of PIP3 was not attenuated by LY2940002. In addition, GnT-V activity in cultured parental or H-ras transfected cells was inhibited by the antibody against PKB or PI-3-K. These findings demonstrated the involvement of PI-3-K/PKB signaling pathway in the regulation of GnT-V. Moreover, ET18-OCH3, an inhibitor of Raf translocation and PI-PLC enzyme, which produces the activator of PKC, as well as the antibodies against Raf-1 or MEK also inhibited GnT-V activity in the parental and H-ras transfected cells. The inhibitory rates, however, were less in the transfected cells than those in the parental cells. These results reveal that in parental and H-ras transfected 7721 cells, the basal activity of GnT-V is also regulated by the Ras/Raf-1/MEK/MAPK cascade in addition to PI-3-K/PKB signaling pathway. The significance of these two pathways in the regulation of GnT-V and their relations to the activation of PKC previously reported by our laboratory (Ju TZ et al., 1995 Glyconjugate J 12, 767-772) was discussed.

Antibodies, Monoclonal↗
PubMed2000

The reliability of cryoSEM for the observation and quantification of xylem embolisms and quantitative analysis of xylem sap in situ.

The reliability of cryoSEM for visualizing gas embolisms in xylem vessels of intact, functioning roots is examined and discussed. The possibility that these embolisms form as a result of freezing water columns under tension is discounted by a double-freeze experiment. Two regions of the same root, one frozen under tension, the other isolated from the tension by the first freeze, had the same percentage of embolisms, as did also long pieces of root frozen simultaneously along their length. The reliability of energy-dispersive X-ray analysis to measure xylem sap concentration in situ in frozen tissue was established by measurement of KCl standard solution frozen on stubs, and within xylem vessels. Solute heterogeneity within the vessels varied with freezing procedure; deep-freeze > LN2 > cryopliers > liquid ethane, but only the deep-freeze method gave unsatisfactory estimates of concentration for the standard solution. It is concluded that cryoanalytical SEM is useful for direct observation of gas and liquid-filled compartments, and for solute analyses at depth within intact plant organs.

Cryoelectron Microscopy↗
PubMed1998

Uncoupling protein mRNA, mitochondrial GTP-binding, and T4 5'-deiodinase activity of brown adipose tissue in Daurian ground squirrel during hibernation and arousal.

The mRNA level of uncoupling protein (UCP) specific for brown adipose tissue (BAT) in Daurian ground squirrel, was detected by using a [32P]-labeled oligonucleotide probe. The UCP concentration in mitochondria was indirectly determined by titration with its specific ligand [H3]-labeled GTP. Type II T4 5'-deiodinase of BAT was assayed concomitantly. We found two species of mRNA for UCP with lengths of about 1.9 and 1.5 kb, respectively, both occurring in almost the same concentration. UCP mRNA content was elevated significantly during hibernation, but the UCP concentration did not change compared with that of nonhibernating controls kept at room temperature. When hibernating squirrels were aroused, the UCP mRNA remained at the elevated level as during hibernation, but the UCP concentration increased in comparison with that of nonhibernating controls or during hibernating. Changes in T4 5'-deiodinase activity in BAT were similar to the variations of the UCP mRNA level. These results suggest that the activation of T4 5'-deiodinase in BAT may be an important factor for the up-regulation and maintenance of UCP mRNA content needed for the synthesis of sufficient UCP to acquire the thermogenic capacity for arousal from hibernation.

Adipose Tissue↗
PubMed1997

[Effect of buyang huanwu decoction on platelet function and fibrinolytic activity of unstable angina pectoris patients].

OBJECTIVE: To explore the effect of Buyang Huanwu Decoction (BYHWD) on the platelet function and fibrinolytic activity of unstable angina pectoris patients. METHODS: Using randomized single blind method divided 60 unstable angina pectoris patients into conventional treatment (control) group and conventional plus BYHWD (TCM) group. RESULTS: BYHWD could lower the levels of platelet aggregation, thromboxane B2 and the inhibitor of fibrinolysinogen activator (P < 0.05), but the activity of histo-type of fibrinolysinogen activator was enhanced. CONCLUSION: BYHWD was effective in treating unstable angina pectoris.

Adult↗
PubMed1997

[Effect of allitridi on expression of proliferating cell nuclear antigen of cultured rabbit aortic smooth muscle cell].

OBJECTIVE: To observe the effect of allitridi on the expression of proliferating cell nuclear antigen (PCNA) of cultured rabbit aortic smooth muscle cell (SMC). METHODS: The expression of PCNA was examined with immunohistochemical technique (LSAB method) and the contents of superoxide dismutase (SOD), lipid peroxide (LPO), prostacyclin (PGI2) and cyclic adenosine monophosphate (cAMP) in medium were simultaneously determined. RESULTS: Allitridi has the effects of increasing SOD activity, decreasing LPO, elevating PGI2 and cAMP, reducing the expression of PCNA (all P < 0.05-0.01). CONCLUSION: Allitridi could inhibit SMC proliferation.

Allyl Compounds↗
PubMed1994

Planing frozen hydrated plant specimens for SEM observation and EDX microanalysis.

A procedure is described for forming a flat face on a frozen piece of plant tissue, which may then be observed fully-hydrated or lightly etched, and coated or uncoated with a metal film, in scanning electron microscopy (SEM). The frozen sample was planed with a glass knife at -80 degrees C in a cryo-ultramicrotome. The sections were discarded, and the planed block face placed on the cold stage in the microscope column, either for observation uncoated at low kV, or for light etching (-90 degrees C) to reveal the cell outlines. If a higher accelerating voltage was needed, the face was given an evaporative coating of Al in the cryo-preparation chamber and returned to the column. The advantages of the planed face over the usual fracture face are illustrated: imaging at a chosen rather than a chance position; clearer cellular and subcellular detail; preservation of hydrated gels like mucilage and swollen cell walls; the possibility of making serial parallel sections through the same piece of tissue; opportunities for accurate morphometric analyses on the planed face; capacity to produce longitudinal sections; preservation of very delicate structures that are destroyed by fixation and drying. A major advantage of the Al-coated planed face is the increased accuracy of energy-dispersive X-ray (EDX) microanalyses on a smooth rather than a rough surface. Tests are included which show that neither the light etching employed, nor successive planing, interferes with the analyses of elements in the frozen face.

Cryopreservation↗