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Biomedical subjects

G Liu

Publications and source records attributed to G Liu.

At least 631 records · Page 35Linked to original sources
PubMed1992

[Atmosphere pollution by sulfur dioxide during processing of zirantong].

This paper reports the colorimetric determination of total SO2 in Zirantong by the method of rosaniline hydrochlorid. Samper of processed Zirantong from the pharmacy have been analyzed and the quality specifications established. Optimum conditions for processing have been chosen and a procedure has been proposed for the recovery of the poisonous matter SO2 which is then transformed into a beneficial material.

Air Pollution↗
PubMed1992

Protective effect of schisanhenol against oxygen radical induced mitochondrial toxicity on rat heart and liver.

Schisanhenol (SAL) had been shown to have potent antioxidant activities. The protective effects of SAL against oxygen radical induced mitochondrial injuries of rat heart and liver were investigated in the present study. The ferrous-cysteine induced mitochondrial lipid peroxidation was significantly inhibited by SAL, while the loss of ATPase activity induced by the lipid peroxidation was prevented. The rigidification of mitochondrial membrane, as well as swelling, lysis and disintegration of the mitochondria induced by ferrous-cysteine were all significantly inhibited by SAL. These results further confirm that SAL possesses antioxidant activity.

Animals↗
PubMed1991

Role of cytochrome P450 IA2 in acetanilide 4-hydroxylation as determined with cDNA expression and monoclonal antibodies.

The role of P450 IA2 in the hydroxylation of acetanilide was examined using an inhibitory monoclonal antibody (MAb) 1-7-1 and vaccinia cDNA expression producing murine P450 IA1 (mIA1), murine P450 IA2 (mIA2), or human P450 IA2 (hIA2). Acetanilide hydroxylase (AcOH) activity was measured using an HPLC method with more than 500-fold greater sensitivity than previously described procedures. This method, which does not require the use of radioactive acetanilide, was achieved by optimizing both the gradient system and the amount of enzyme needed to achieve detection by uv light. MAb 1-7-1 inhibits up to 80% of the AcOH activity in both rat liver microsomes and cDNA expressed mouse and human P450 IA2. MAb 1-7-1, which recognizes both P450 IA1 and P450 IA2, completely inhibits the aryl hydrocarbon hydroxylase (AHH) activity of cDNA expressed in IA1. The inhibition of only 80% of the AHH activity present in MC liver microsomes by MAb 1-7-1 suggests that additional P450 forms are contributing to the overall AHH activity present in methylcholanthrene (MC)-liver microsomes as MAb 1-7-1 almost completely inhibits the AHH activity of expressed mIA1. Maximal inhibition of IA2 by 1-7-1 results in an 80% decrease in acetanilide hydroxylase activity in both liver microsomes and expressed mouse and human IA2. The capacity of MAb 1-7-1 to produce identical levels of inhibition of acetanilide hydroxylase activity in rat MC microsomes (80%) and in expressed mouse (81%) and human P450 IA2 (80%) strongly suggests that P450 IA2 is the major and perhaps the only enzyme responsible for the metabolism of acetanilide. These results demonstrate the complementary utility of monoclonal antibodies and cDNA expression for defining the contribution of specific P450 enzymes to the metabolism of a given substrate. This complementary approach allows for a more precise determination of the inhibitory capacity of MAb with respect to the metabolic capacity of the target P450.

Acetaminophen↗
PubMed1991

Respiratory pattern generation in mammals: in vitro en bloc analyses.

The development of in vitro en bloc preparations of mammalian neuraxis that retain functional circuits for respiratory pattern generation has led to novel observations that have expanded our understanding of this important motor/homeostatic system. This experimental approach is a powerful and unique way to study complex integrative neural function concurrently at cellular, synaptic, and network levels.

Animals↗
PubMed1991

Evidence of cyclic GMP may regulate the association of myosin II heavy chain with the cytoskeleton by inhibiting its phosphorylation.

Previous studies have implicated cyclic GMP in the regulation of myosin II heavy chain (MHC) association with the cytoskeleton in Dictyostelium discoideum. Here we provide evidence that cyclic GMP may regulate MHC association with the cytoskeleton through MHC phosphorylation. Comparative data are presented of MHC phosphorylation in the wild-type strain NC4, the parental strain XP55 and streamer mutants NP368 and NP377. Using an anti-MHC monoclonal antibody to immunoprecipitate MHC from [32P]phosphate-labelled developing cells, we found that cyclic AMP stimulation of the wild-type strain NC4 and parental strain XP55 induced MHC phosphorylation in vivo. A peak of phosphorylation was observed at 30-40 s, followed by a gradual decrease to basal level at 160 s. In contrast, in both of the streamer mutants NP368 and NP377 (which have prolonged cyclic GMP accumulation and prolonged MHC association with the cytoskeleton), the phosphorylation of MHC was delayed and did not form a peak until 60-80 s after cyclic AMP stimulation. We also found that cytoskeletal MHC showed only minor phosphorylation, the majority of the phosphorylated MHC being found in the cytosol. We present a model to account for these results in which cyclic GMP regulates MHC association with the cytoskeleton by regulating the phosphorylation/dephosphorylation cycle of MHC in these cells.

Animals↗
PubMed1991

[Biomechanical characteristics of the trachea and its reconstruction].

Under uniaxial loading, the mechanical properties of fifteen canine tracheas were tested by CSS-2100 electronic universal testing machine, (produced by Changchun Institute of Testing Machines), which was equipped with X-Y recorder, deformation testing gauge and Super Computer, etc. Tracheas of 22 healthy adult dogs were divided into 3 groups. The 1st group contained normal tracheas, the 2nd group contained tracheas medially cut and the tension test. These features from one-dimension tensile anastomosed end-to-end with 0.2 mm silk sutures. The 3rd group contained those anastomosed with 0.3 mm silk sutures. The results showed that in the 1st group although there was a nonlinear stress-strain relationship, the linear segment was not clear. The stress produced by the suture formed the incisive force because of small section area and stress concentration. The thickness of the membrane paries of the canine trachea was greater than that of the annular ligament, but smaller than that of the cartilage ring. The length of the membrane paries was smaller than that of the cartilage ring. Consequently, an uneven stress distribution was seen. The results of this experiment might serve as a basis for further research on the biomechanical implications of human trachea reconstruction.

Anastomosis, Surgical↗
PubMed1991

[Protective action of biphenyl dimethyl dicarboxylate (DDB) against liver nuclear DNA damage induced by carcinogens].

The protective effect of DDB against carcinogen-induced DNA damage was examined in the present investigation. Preincubation of rat liver nuclei with DDB (1 mmol/L) resulted in inhibition of binding of 3H-benzo (a) pyrene to nuclear DNA. The inhibition rate was about 60%. Unscheduled DNA synthesis (UDS) of freshly isolated rat hepatocytes induced by aflatoxin B1 (10(-7) mol/L) was also dose dependently inhibited by DDB (10(-6)-10(-3) mol/L). Oral administration of DDB at 200 mg/kg once daily for 3 days was effective to induce increase of liver cytosol glutathione-S-transferase and microsomal UDPG-transferase in mice. The results indicate that DDB is able directly or indirectly to antagonize certain carcinogen-induced DNA damages.

Aflatoxin B1↗
PubMed1991

[Gene diagnosis of adult polycystic kidney disease--linkage analysis between APKD gene and alpha-globin gene 3'HVR].

Genomic DNA PvuII fragments containing the 3'HVR from 52 unrelated Chinese of Han nationality varied between 1.7 kb and 10.0 kb and showed high polymorphism. The genomic DNA PvuII fragments from five families with adult polycystic kidney disease (APKD) were analyzed using the alpha-globin gene 3' HVR (hypervariable region) as probe. The results showed a close linkage between 3'HVR and the APKD gene and segregation according to Mendelian laws. The maximum Lod score for linkage between 3' HVR and APKD was 3.372 at a recombination fraction theta = 0.01. The alpha-globin gene 3'HVR probe can therefore be used for presymptomatic gene diagnosis and prenatal diagnosis in the Han ethnic group.

DNA Probes↗
PubMed1991

[Gas chromatographic analysis of alcohols, aldehydes and esters in potable spirits].

The determination of alcohols, aldehydes and esters in potable spirits was accomplished with a new kind of chromatographic packing made in China--graphitized carbon black (SHT2), modified with PEG-20M. By means of programmed temperature and direct injection, quantitative measurements of 22 components in potable spirits can be simultaneously finished in 50 min. The detect limit of the method was 1 ppm. The coefficients of variation were less than 10%. The recovery tests of 11 components were carried out and the recoveries were in the range of 81.0-106.8%. The method can be applied not only to hygienic monitoring of methanol, fusel oil and furfural, but also to quantitative monitoring of aromatic components in potable spirits. The measurements of several Sichuan spirits samples were made with satisfactory results.

Alcoholic Beverages↗
PubMed1991

[An analysis of the factors influencing the use of IUD].

An introduction of the method of the theory of quantification II is given, and it is applied to evaluation of the factors influencing the use of IUD. From the epidemiological data obtained in Jilin City, eight more important factors were screened. These factors are age of first parturition, age of first menses, condition of putting the IUD in, number of early stage induced abortion, number of gestation, labour posture, labour intensity and number of parturition. By comparing the results of analysis between the theory of the quantification and the Bayes discrimination analysis, it is shown that the former method is more objective and therefore the results are more reliable.

Bayes Theorem↗
PubMed1991

[Research on karyotypic consistency between chorionic villi and fetus].

In the last decade, chorionic villi sampling (CVS) has been widely accepted as a new technique in prenatal diagnosis. An inconsistency in karyotypes between CVS and fetal tissue was found in clinical practice, although the chorionic villi and the fetal tissues were from the same fertilized ovum. Karyotypes from direct chromosomal preparation of chorionic villi and cultured fetal tissues in 52 artificial abortion samples were compared. Results showed two cases with karyotypic inconsistency: (1) 46, XX/46, XY in the chorionic villus direct preparation and 46, XX in the fetal tissue; (2) 46, XY in the direct preparation of chorionic villi and 45,XY, t (15q21q) de novo in the fetal tissue. Our research demonstrates that karyotype from chorionic villus direct preparation does not always reflect the fetal karyotype.

Adult↗
PubMed1990

Synthetic peptide antigens elicit monoclonal and polyclonal antibodies to cytochrome P450 IA2.

Two peptide sequences from cytochrome P450 IA2 were synthesized, coupled to ovalbumin and used as antigens to generate anti-peptide monoclonal and polyclonal antibodies. Antisera to both peptides reacted with rat IA2 but not the structurally similar IA1 form as determined by enzyme-linked immunosorbent assay. However, antisera to both peptides detected both rat IA2 and IA1 on immunoblots. In addition immunoblots of human liver microsomes revealed that both antisera recognized human IA2, but not IA1. Monoclonal antibodies generated against one of the peptides recognized rat IA2 and IA1 but did not detect human IA2. These results demonstrate the utility of anti-peptide antisera as a practical approach for the generation of P450 specific antibodies.

Amino Acid Sequence↗
PubMed1990

Organization of the auditory area in the posterior cerebellar vermis of the cat.

We mapped the topographic distribution of auditory responses in the posterior cerebellar vermis of the cat under barbiturate anesthesia. Auditory neurons in the granule cell layer of lobules VI and VII appeared to be arranged in columns perpendicular to the surface of the cerebellar cell layers. Mapping the surface of the cerebellum, auditory responses were found as separated patches of the order of a square millimeter. Neurons on these patches responded to auditory stimuli but neurons between patches did not respond to sound. In decerebrated cats, the entire granule cell layer within the cerebellar auditory area responded to acoustic stimulation without a patchy pattern. Responses to tonal stimuli from single neurons in the granule cell layer were studied before and after the induction of barbiturate anesthesia. Some neurons showed no change in their responses to sound before and under barbiturate. But other neurons showed dramatically attenuated responses or essentially stopped responding as a result of barbiturate anesthesia. These results suggest that there may be two types of granule cells distinguishable in their auditory responses and therefore possibly in function.

Acoustic Stimulation↗