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Biomedical subjects

H Liang

Publications and source records attributed to H Liang.

At least 73 records · Page 4Linked to original sources
PubMed2000

Application of combined genetic algorithms with cascade correlation to diagnosis of delayed gastric emptying from electrogastrograms.

The current standard method (radioscintigraphy) for the diagnosis of delayed gastric emptying (GE) of a solid meal involves radiation exposure and considerable expense. Based on combining genetic algorithms with the cascade correlation learning architecture, a neural network approach is proposed for the diagnosis of delayed GE from electrogastrograms (EGGs). EGGs were measured by placing surface electrodes on the abdominal skin over the stomach in 152 patients with suspected gastric motility disorders for 30 min in the fasting state and for 2 h after a standard test meal. The GE rate of the stomach was simultaneously monitored after the meal using radioscintigraphy. Five spectral parameters of EGG data in each patient were used as the inputs to a classifier. The classifier was designed by using genetic algorithms in conjunction with the cascade correlation learning architecture. The main advantage of this technique over the back-propagation (BP) for supervised learning is that it can automatically develop the architecture of neural networks to give a suitable network size for a specific problem. The resulted neural network with three hidden units exhibits 83% correct classification for the EGG data, and has comparable performance with the BP network. This study demonstrates the potential of the neural network approach based on combined genetic algorithms with cascade correlation for diagnosis of gastric emptying from the EGG.

Algorithms↗
PubMed2000

Effect of pH and Zn(2+) on subcultured muscle cells from Macrobrachium nipponense.

A cell culture system was devised for muscle cell of Macrobrachium nipponense in the study. The juvenile and adult shrimps were held in laboratory aquaria with penicillin 1000 IU/ml and streptomycin 1000 microg/ml for 12-24 hours. Cell cultures were established in medium 199 supplemented with 20% fetal bovine serum, 1 g/L glucose, 5.2 g/L NaCl, 1.43 g/L CaCl(2), 0.05 g/L MgCl(2), 100 IU/mL penicillin and 100 microg/ml streptomycin. Fibroblast-like cells were passaged up to three times and survived for 54 days. The results showed the optimum for subculture in vitro was in medium 199 with pH 7.6. Moreover, basal medium supplemented with Zn(2+) 60 microg/L could enhance the growth of the muscle cells. It was found that better results for cell culture would be obtained more easily with juvenile shrimps caught in spring than adults in summer or autumn; and shrimps caught within 12 hours after ecdysis could grow much better than the intermoult shrimps.

Animals↗
PubMed2000

Galalpha(1,3)Gal epitope in porcine small intestinal submucosa.

Small intestinal submucosa (SIS) is a naturally occurring, acellular biomaterial derived from porcine jejunum, which promotes constructive tissue remodeling when applied as a xenogeneic graft material. Galactosyl-alpha(1,3)galactose (Gal) is a cell-associated epitope responsible for hyperacute rejection of porcine whole-organ xenografts in primates. Because SIS is harvested from porcine tissue, it may contain the Gal epitope. The goals of this study were to determine if Gal is present in SIS and, if it is present, to determine if human serum complement can be activated in vitro following exposure to porcine-derived SIS. SIS was probed for Gal by immunohistochemical methods and by lectin-peroxidase staining. SIS stained strongly positive with human serum, which contains naturally occurring antibodies to Gal, followed by anti-immunoglobulin G (IgG) or anti-IgM peroxidase conjugate. Blocking with the lectin I-B(4), which is specific for the Gal epitope, decreased the intensity of staining. Exposure of SIS to alpha-galactosidase reduced staining to negligible amounts. The Gal epitope is distributed transmurally throughout the SIS material. Subtyping of the immunoglobulins that bind to SIS showed that IgG(2) is the major immunoglobulin of human plasma that binds to SIS. SIS did not activate complement in vitro as measured by radioimmunoassay for C3a.

Animals↗
PubMed2000

Effects of benzyl isothiocyanate and phenethyl isothiocyanate on benzo[a]pyrene metabolism and DNA adduct formation in the A/J mouse.

Benzyl isothiocyanate (BITC) inhibits lung tumorigenesis induced in A/J mice by benzo[a]pyrene (B[a]P). In contrast, phenethyl isothiocyanate (PEITC) does not. We tested the hypothesis that BITC inhibits B[a]P tumorigenicity in mouse lung by inhibiting DNA adduct formation, and compared the effects of BITC and PEITC. In mouse liver or lung microsomal incubations, BITC and PEITC inhibited formation of 7,8-dihydro-7,8-dihydroxybenzo[a]pyrene (B[a]P-7, 8-diol) and some other B[a]P metabolites. The metabolism of B[a]P was compared in mouse lung and liver microsomes, 6 or 24h after treatment with BITC or PEITC. In lung, 6 h after treatment, B[a]P-7, 8-diol and some other metabolites were inhibited by BITC and PEITC. However, 24 h after treatment, no inhibition of B[a]P-7,8-diol was observed in microsomes from BITC-treated mice, whereas it was substantially increased in mice treated with PEITC. Effects on B[a]P metabolism in liver microsomes were generally modest. Conversion of B[a]P-7,8-diol to mutagens by mouse liver microsomes was more strongly inhibited by BITC than PEITC. Effects on 7,8-dihydroxy-9, 10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE)-DNA adduct formation were evaluated in DNA from mice treated with isothiocyanates and B[a]P, and killed 2-120h later. The area under the curve (AUC) for BPDE-DNA adducts in lung was 29.5% less (P = 0. 001) in the BITC-B[a]P treated mice and 19.0% less (P = 0.02) in the PEITC-B[a]P mice than in the mice treated with B[a]P alone. Similar results were obtained in liver DNA. There were no significant differences between the reduction of BPDE-DNA AUC values by BITC versus PEITC. The results of this study support the hypothesis that BITC inhibits B[a]P-induced lung tumorigenesis in A/J mice by inhibiting the metabolic activation of B[a]P to BPDE-DNA adducts. However, differences in BPDE-DNA adduct formation do not appear to explain fully the contrasting effects of BITC and PEITC on B[a]P-induced lung tumorigenesis.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed2000

Uncoupling salicylic acid-dependent cell death and defense-related responses from disease resistance in the Arabidopsis mutant acd5.

Salicylic acid (SA) is required for resistance to many diseases in higher plants. SA-dependent cell death and defense-related responses have been correlated with disease resistance. The accelerated cell death 5 mutant of Arabidopsis provides additional genetic evidence that SA regulates cell death and defense-related responses. However, in acd5, these events are uncoupled from disease resistance. acd5 plants are more susceptible to Pseudomonas syringae early in development and show spontaneous SA accumulation, cell death, and defense-related markers later in development. In acd5 plants, cell death and defense-related responses are SA dependent but they do not confer disease resistance. Double mutants with acd5 and nonexpressor of PR1, in which SA signaling is partially blocked, show greatly attenuated cell death, indicating a role for NPR1 in controlling cell death. The hormone ethylene potentiates the effects of SA and is important for disease symptom development in Arabidopsis. Double mutants of acd5 and ethylene insensitive 2, in which ethylene signaling is blocked, show decreased cell death, supporting a role for ethylene in cell death control. We propose that acd5 plants mimic P. syringae-infected wild-type plants and that both SA and ethylene are normally involved in regulating cell death during some susceptible pathogen infections.

Apoptosis↗
PubMed2000

Antibodies against the Plasmodium falciparum receptor binding domain of EBA-175 block invasion pathways that do not involve sialic acids.

The 175-kDa Plasmodium falciparum erythrocyte binding protein (EBA-175) binds to its receptor, sialic acids on glycophorin A. The binding region within EBA-175 is a cysteine-rich region identified as region II. Antibodies against region II block the binding of native EBA-175 to erythrocytes. We identified a P. falciparum strain, FVO, that could not invade erythrocytes devoid of sialic acids due to prior neuraminidase treatment, and in addition, we used a strain, 3D7, that could invade such sialic acid-depleted erythrocytes. We used these two strains to study the capacity of anti-region II antibodies to inhibit FVO and 3D7 parasite development in vitro. Analysis of growth-inhibitory effects of purified FVO anti-region II immunoglobulin G (IgG) with the FVO and 3D7 strains resulted in similar levels of growth inhibition. FVO and 3D7 strains were inhibited between 28 and 56% compared to control IgG. There appeared to be no intracellular growth retardation or killing of either isolate, suggesting that invasion was indeed inhibited. Incubation of recombinant region II with anti-region II IgG reversed the growth inhibition. These results suggest that antibodies against region II can also interfere with merozoite invasion pathways that do not involve sialic acids. The fact that EBA-175 has such a universal and yet susceptible role in erythrocyte invasion clearly supports its inclusion in a multivalent malaria vaccine.

Animals↗
PubMed2000

A recombinant baculovirus-expressed Plasmodium falciparum receptor-binding domain of erythrocyte binding protein EBA-175 biologically mimics native protein.

EBA-175 of Plasmodium falciparum is a merozoite ligand that binds its receptor glycophorin A on erythrocytes during invasion. The ligand-receptor interaction is dependent on sialic acids as well as the protein backbone of glycophorin A. Region II (RII) of EBA-175 has been defined as the receptor-binding domain. RII is divided into regions F1 and F2, which contain duplicated cysteine motifs. We expressed RII in a baculovirus and show that RII binds erythrocytes with a specificity identical to that of the native protein. We found that, consistent with the binding of erythrocytes to COS cells expressing F2, recombinant baculovirus-expressed F2 bound erythrocytes. About 20% of all baculovirus-expressed RII is N-glycosylated, unlike native P. falciparum proteins that remain essentially unglycosylated. However, glycosylation of recombinant RII did not affect its immunogenicity. Antibodies raised against both glycosylated and unglycosylated baculovirus-expressed RII recognized P. falciparum schizonts in immunofluorescence assays and also gave similar enzyme-linked immunosorbent assay titers. Furthermore, these antibodies have similar abilities to block native EBA-175 binding to erythrocytes. These results allow the development of RII as a vaccine candidate for preclinical assessment.

Animals↗
PubMed2000

Developmental changes in antioxidant enzymes and oxidative damage in kidneys, liver and brain of bcl-2 knockout mice.

While programmed cell death is induced by a variety of internal and external stimuli, including reactive oxygen species, the anti-apoptotic protein Bcl-2 is involved in opposing cell death and affects the antioxidant status of cells. Since the exact mechanism of its action is uncertain, in this study we examined the role of Bcl-2 using a loss of function model, Bcl-2 knockout mice. The consequence of Bcl-2 knockout was assessed in kidneys, liver and brain, using protein carbonyls and cellular levels of antioxidant enzymes as markers of oxidative stress. Kidney extracts from 8 days-old Bcl-2-knockout mice had 59% higher content of protein carbonyls relative to the wild type, but similar levels of oxidized proteins at the age of 30 days. By marked contrast, in liver and brain, levels of protein carbonyls were similar at 8 days but by 30 days the liver of knockout animals (and brains, as we have shown previously) show 36% higher protein carbonyls. Measures of glutathione reductase (GRX), glutathione transferase (GST) and catalase revealed significantly higher levels in kidneys of 8 days old Bcl-2-knockout mice compared to wild type. By 30 days activities of glutathione-related enzymes and catalase increased and abolished the differences between the knockout and wild type. At 8 days, in liver there were no significant differences in activities of all enzymes between the mice, however by 30 days, the specific activity of GRX was significantly higher in Bcl-2-knockout mice, relative to controls. From day 8 to day 30 there was an increase in liver catalase activity that resulted in significantly higher levels in Bcl-2-knockout animals. Catalase activity in brains of Bcl-2-knockout, 8 days old mice was significantly higher compared to the wild type, and significantly lowers at 30 days. Taken together our findings indicate that Bcl-2 knockout results in significant perturbations of oxidative metabolism and antioxidant status of in kidney, liver and brain. Such changes are tissue specific with respect to age, magnitude and type of enzyme affected.

Animals↗
PubMed2000

[Estimation of biolistic transformation effect by transient expression of C1-R regulatory genes of anthocyanin biosynthesis].

In the present study, the transient expression of maize C1-R regulatory genes of anthocyanin biosynthesis in maize calli, wheat immature embryos, rice calli and tobacco leaves were described. C1-R regulatory genes could activate anthocyanin biosynthesis in vivo and the pigmented cells were visible. For major crops, including maize, wheat and rice, which were transformed mainly by biolistic method, C1-R genes were novel visible markers, and the expression was easier to detect than GUS gene. And these genes also worked well in transient expression in biolistic transformation system of tobacco leaves.

Anthocyanins↗
PubMed2000

[The genetic behavior of an Agropyron intermedium chromosome conferring BYDV resistance in wheat background].

Based on the chromosome origin identification of an Agropyron intermedium chromosome with BYDV resistance in Yi4212, a BYDV-resistant substitution line derived from the hybrids between 77-5433 and Zhong5, its ability compensating the lost wheat chromosomes and its transmission rate were investigated. The results indicated that the BYDV-resistant chromosomes originated from Zhong 5 could compensate the wheat chromosomes of homotologous group 2, 5 and 7. The chromosome conferring resistance to BYDV showed the intendance to substitute 2D rather than 2A, 2B wheat chromosomes in disomic substitution lines. In (77-5433/Zhong 5) selfing F2 population, 10 kinds of chromosome constitutions, including 9 expected and 1 unexpected kinds, and much chromosome number variation and little chromosome structure variation were observed. The transmission rate of the BYDV-resistant chromosome and the gametes carrying this chromosome were 56.3% and 33.0% respectively, both are lower than the expected ratio 75.0% and 50.0%. Some reasons were given to explain the related results, and chromosome in situ hybridization was an efficient and accurate way in studying the alien chromosome behavior in wheat background.

Chromosomes↗
PubMed2000

Electron-microscopic detection of apoptotic and necrotic cell death in non-atherosclerotic areas of stenotic aortocoronary saphenous vein bypass grafts.

Aortocoronary saphenous vein bypass grafts undergo structural alterations within the arterialized vein, resulting in graft stenosis and failure. Areas of the acellular intima contribute to fissuring, cracking and ulceration, while areas of the media become highly vascular but thinned. This study aimed to examine the ultrastructural features of cell death, including apoptosis and necrosis, in non-atherosclerotic areas of the stenotic aortocoronary saphenous vein bypass grafts. Thirteen stenotic vein grafts were obtained at redo coronary artery bypass grafting. The ultrastructural features of cell death were analysed by electron microscopy. Typical features of necrosis, including focal areas of cytoplasmic oedema, plasmalemmal destruction and nuclear condensation with cytoplasmic organelle destruction, were observed throughout the intima and media. Features of apoptosis, including the presence of apoptotic bodies, were also identified in the hyperplastic intima and its adjacent media. Our observations suggest that both apoptosis and necrosis occur in non-atherosclerotic areas of stenotic aortocoronary saphenous vein bypass grafts.

Aged↗
PubMed2000

[Fluorescence in situ hybridization applied to the meiotic analysis and spontaneous chromosome translocation in the pollen mother cells of hybrids of Triticum-Haynaldia].

Fluorescence in situ hybridization was applied to the meiotic analysis and chromosome pairing in the pollen mother cells of hybrids of Triticum-Haynaldia. The results indicated that most (90.5%-93.2%) of the PMCs of two Triticum-Haynaldia hybrids contained two univalents involving one Haynaldia chromosome at metaphase I, and only 1 of 320 PMCs with homologous pairing between one wheat chromosome and one Haynaldia chromosome was observed in the hybrid of Guinong 22 x common wheat Chinese Spring, the frequency was 0.3%. The frequencies of the PMCs with mis-dividing chromosome ranged from 32.7% to 37.5% at anaphase I and from 20.5% to 24.4% at anaphase II in the hybrids between Triticum-Haynaldia. The frequency of Haynaldia chromatin translocating into Triticum chromosome was about 0.7% at anaphase I in the hybrid of Guinong 22 x common wheat Chinese Spring and was 0.8%-1.7% at anaphase II in two wheat-Haynaldia hybrids. Otherwise, the chromosome morphology involving Haynaldia chromatin was observed at preleptotene I, and the frequencies of chromatin nucleus at tetrad stage and at microspore stage were investigated. The time of chromosome translocation in meiosis and the transmitting frequencies of Haynaldia chromosome in wheat background were discussed.

Gene Frequency↗
PubMed2000

[Measure of vibration protection effect of driver's corset and analysis of its biomechanical effect].

The purpose of this study was to evaluate the vibration protection and biomechanical effect of driver's corset. The frequencies of vertfical and horizontal vibrations were measured at low back of driver. The vehicle driven was ISUZU truck (loading capacity 8 tons). Vibration of the driver's lumbar back was measured real time with wear corset and without wear corset when the truck loaded with 6 tons was driven at the spead of ten, thirty and sixty kilometers an hour on the asphalt road. The results showed: 1. Vibration frequencies at driver's low back was under 10 Hz. It is a low frequency vibration. 2. The value of vertical vibration was higher than the value of horizontal (back and forth) vibration. 3. The vibration value of wear corset was higher than un-wear corset. These indicate the driver's corset is effective for protecting lumbar spine by means of change in the biomechanical characteristics and the resonace requencies of lumbar spine. So the driver's corset is one of the good methods for preventing the back pain of drivers.

Automobile Driving↗
PubMed2000

[Dynamic changes of respiration pathway and active oxygen levels in subcultured tobacco callus].

During the growth and senescence of tobacco callus, the total respiration rate showed two peaks on the 11th and 19th day, respectively. The development and operation of alternative pathway increased gradually, reached the maximum between two respiration peaks, and then declined in the following days, but the cytochrome pathway was still as a main electron transport pathway consistently. Analysis on the levels of active oxygen species during the growth and senescence process in tobacco callus suggested that H2O2 and O2.- were involved in some way in the induction of the development and operation of the alternative pathway, but the increase of production rate of OH might suppress both the development and operation of the alternative pathway, which were enhanced by H2O2 and O2.- respectively. These results were further proved by the use of active oxygen scavengers. The possible participation of the alternative pathway enhanced by active oxygen in the initial senescence process was discussed.

Cells, Cultured↗
PubMed2000

[Study on relationship of parameters of nitric oxide, endothelin and blood stasis syndrome in traditional Chinese medicine in acute cerebral infarction].

OBJECTIVE: To explore the relationship of parameters of nitric oxide (NO), endothelin (ET) and blood stasis syndrome (BSS) of traditional Chinese medicine (TCM) in acute cerebral infarction (ACI). METHODS: Seventy-three patients of ACI (ACI group) were divided into two groups by the score of BSS: BSS group (included 18 cases of serious BSS, 19 cases of moderate BSS, and 21 cases of mild BSS); and non-BSS group (15 cases); while 30 healthy subjects were taken as the control group, their NO and ET were determined. RESULTS: Compared with the control group, the level of ET and ratio of ET/NO raised significantly in the ACI group and the BSS group (P < 0.01). The levels of ET and ratio of ET/NO of mild, moderate and serious BSS increased in order, but only the serious BSS in comparing with mild, moderate group of BSS had significant difference (P < 0.01). The NO levels of ACI group, non-BSS group in comparing with healthy control, there was significant decrease (P < 0.05, P < 0.01). The NO concentration among the mild, moderate and serious group of BSS had insignificant difference (P > 0.05). CONCLUSION: NO and ET participates the formation and development of ACI, owing to the disturbed NO and ET secretion by vascular, nerve cells etc., these might be the pathologic basis of BSS occurrence.

Acute Disease↗
PubMed2000

[Effect of different injections of Chinese herbal medicine on stress hormones and immune cell factors in patients of type 2 diabetes mellitus complicated with acute cerebral infarction].

OBJECTIVE: To investigate the effect and clinical significance of different injections of Chinese herbal medicine on stress hormones and immune cell factors in treating patients of type 2 diabetes mellitus complicated with acute cerebral infarction. METHODS: Patients were divided into three groups, treated with Defibrase injection (DI, n = 32), Acanthopanax injection (AI, n = 20) and Ginaton injection (GI, n = 12) respectively. Parameters, including corticotropin-releasing hormone (CRH), adrenocoticortropic hormone (ACTH), cortisol (CS), tumor necrosis factor alpha (TNF alpha) and interleukin-6 (IL-6) were determined using RIA in patients before and after treatment. The changes of parameters were analyzed and compared with those of healthy subjects for control. RESULTS: (1) Levels of all the above-mentioned parameters in all the three treated groups were higher than those in the healthy control group (P < 0.01); (2) All parameters were reduced after treatment in the three treated groups and the optimal effect was shown in the DI group (P < 0.01). CONCLUSION: The beneficial action of the three injections is closely related with the levels of stress hormones and immune cell factors, therefore, to monitor dynamically the changes of CRH, ACTH, CS, TNF alpha and IL-6 is of important significance in evaluation of therapeutic effect and elucidation of the pharmacology of Chinese herbal medicine.

Adrenocorticotropic Hormone↗
PubMed2000

[Determination of O6-methylguanine by high performance capillary zone electrophoresis].

In this paper, a method to determine O6-methylguanine in urine by high performance capillary zone electrophoresis has been established. O6-methylguanine was directly introduced into the capillary employing sodium borate at pH 9.0 as buffer. The capillary used was 75 microns i.d. x 57 cm. The calibration curve showed good linearity, r = 0.9987, CVs were 1.51% for intra-day and 1.93% for inter-day. The average recovery was 98.2%. In conclusion, this method is a simple, rapid, precise and reliable technique for O6-methylguanine measurement in urine.

DNA Adducts↗