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Biomedical subjects

J Z Liu

Publications and source records attributed to J Z Liu.

At least 55 records · Page 3Linked to original sources
PubMed1992

Age, dietary selenium and quantity of 7,12-dimethylbenz(a)anthracene influence the in vivo occurrence of rat mammary DNA adducts.

The present studies determined the impact of age, dietary selenium and 7,12-dimethylbenz(a)anthracene (DMBA) dosage on the occurrence of DMBA-DNA adducts in rat mammary tissue. Diets formulated to contain selenium, as sodium selenite, at 0.1 (control) or 2.0 mg/kg were fed for 2 wk before DMBA treatment. Food intake and weight gain were not influenced by selenium intake. Anti- and syn-dihydrodiol epoxide adducts reached maximum binding by 24 and 36 h, respectively, after treatment with DMBA. Consumption of the diet containing 2.0 mg Se/kg inhibited the appearance of both anti- and syn-adducts by approximately 50% compared with controls. The occurrence of DMBA-DNA adducts correlated with a dosage of DMBA from 5 to 50 mg/kg body wt (r greater than or equal to 0.95). The ability of supplemental selenite to lower DMBA binding to mammary cell DNA increased as the quantity of the carcinogen administered increased. DMBA-DNA binding was found to increase with the increasing age of the rat. Nevertheless, dietary selenium supplementation was effective in reducing DMBA binding to DNA in all ages examined. These data confirmed the ability of dietary selenium to inhibit the in vivo metabolism of DMBA under a variety of conditions.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1991

Inhibition of 7,12-dimethylbenz(a)anthracene-induced mammary tumors and DNA adducts by dietary selenite.

The present studies were designed to examine the influence of dietary selenite supplementation on the initiation phase of 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinogenesis and to correlate selenite-induced changes in the binding of DMBA metabolites to rat mammary cell DNA with the ultimate tumor incidence. Diets formulated to contain selenium, as sodium selenite at 0.1, 0.5, 1, 2, or 4 micrograms/g were fed for 2 weeks prior to and 2 weeks following treatment with DMBA (5 mg/kg body weight). Food intake and weight gain did not differ among treatments. Tumor incidence correlated inversely to the quantity of selenium consumed (r = -0.99). Final tumor incidences were 52, 32, 24, 14, and 10% for rats fed 0.1, 0.5, 1, and 4 micrograms selenium/g, respectively. In a separate group of rats fed a diet containing 4 micrograms selenium/g during both the initiation and promotion stages the final tumor incidence was 4.8%. Selenite supplementation for 2 weeks markedly depressed the occurrence of individual and total DMBA-DNA adducts. The final mammary tumor incidence correlated positively with total DMBA-DNA adducts (r = 0.99). These studies clearly demonstrate that selenite can inhibit the initiation stage of mammary carcinogenesis. This reduction in tumor incidence is likely due to a reduction in carcinogen metabolism and ultimately adduct formation.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1990

Ion selectivity of the Vibrio alginolyticus flagellar motor.

The marine bacterium, Vibrio alginolyticus, normally requires sodium for motility. We found that lithium will substitute for sodium. In neutral pH buffers, the membrane potential and swimming speed of glycolyzing bacteria reached maximal values as sodium or lithium concentration was increased. While the maximal potentials obtained in the two cations were comparable, the maximal swimming speed was substantially lower in lithium. Over a wide range of sodium concentration, the bacteria maintained an invariant sodium electrochemical potential as determined by membrane potential and intracellular sodium measurements. Over this range the increase of swimming speed took Michaelis-Menten form. Artificial energization of swimming motility required imposition of a voltage difference in concert with a sodium pulse. The cation selectivity and concentration dependence exhibited by the motile apparatus depended on the viscosity of the medium. In high-viscosity media, swimming speeds were relatively independent of either ion type or concentration. These facts parallel and extend observations of the swimming behavior of bacteria propelled by proton-powered flagella. In particular, they show that ion transfers limit unloaded motor speed in this bacterium and imply that the coupling between ion transfers and force generation must be fairly tight.

Cell Movement↗
PubMed1990

Study on BcII/St14 RFLPs in Chinese for DNA diagnosis for hemophilia A.

The BcII polymorphism within DXS52 (St14) was reported. It was composed of 4 allelic fragments, 4.0 kb, 3.3 kb, 3.0 kb and 2.3 kb. The frequency of these fragment were 0.09, 0.12, 0.44 and 0.35 respectively in the Chinese. The polymorphism provided the PIC of 0.66. DNA analysis of families with hemophilia A showed that the confidence of the RFLPs was the same as the TaqI/St14 RFLPs and for carrier detection the former is much better than that of the TaqI/St14 RFLPs.

China↗
PubMed1989

Studies of beta-thalassemia mutations in families living in three provinces in southern China.

beta-Thalassemia is a common disease in Southern China and 10 different mutations or frameshifts are responsible for most types of beta-thalassemia in this area. We studied 126 chromosomes of 80 beta-thalassemia patients from the Guangxi, Guangdong, and Sichuan Provinces using the polymerase chain reaction followed by dot-blot hybridization with specific oligonucleotide probes. The most common mutation in the three provinces is the frameshift at codons 41-42, followed by the A----T mutation at codon 17. The A----G mutation at nt -29 of the promoter is common in Sichuan but not in the other two provinces. Three mutations (T----C at nt -30; G----T at IVS-I-1, and G----C at IVS-I-5) were not observed. These data were used to initiate a prenatal diagnosis program using the same techniques for identification. Eleven fetuses at risk for beta-thalassemia have been diagnosed.

Base Sequence↗
PubMed1989

Operation of fluidized-bed bioreactor containing immobilized yeast cells and the diacetyl levels of green beer.

A fluidized-bed bioreactor containing yeast cells immobilized in calcium alginate gel was operated by means of a circulating wort system. The optimum volume fraction of gel beads was found to be 0.40 (phi, v/v) for fermentation. The effects of the flow rates of the wort on the period of the primary fermentation and the diacetyl levels in green beer were studied under the conditions of the volume fraction of gel beads at phi = 0.40, the fermentation temperature at 10 degrees C, and the ratio of circulation at n = 5. The experimental results indicated that the period of the primary fermentation was shortened as the flow rate of wort increased, whereas the concentration of diacetyl increased with the increasing flow rate of the wort. The period of the primary fermentation and the concentration of the diacetyl were found to be 14 h and 0.5 ppm respectively, when the residence time tau t in the reactor was 2.8 h.

Beer↗
PubMed1989

[The RFLPs of St14/Taq I in Chinese and its application to gene analysis and prenatal diagnosis of hemophilia A].

The genomic DNA fragment St14 (DXS52) is located in q28 region of X chromosome that also contains the hemophilia A locus. The RFLPs of St14/Taq I in Chinese were studied. The frequency of allele 7A (3.6 kb) is 31%, which is obviously different from the data reported abroad. By use of the RFLPs, 8 families with hemophilia A were analysed, including 1 case for first trimester prenatal diagnosis at risk of hemophilia A.

Asian People↗
PubMed1989

A study of sex identification of trace, dried bloodstains using a Y-chromosome-specific deoxyribonucleic acid (DNA) probe.

A new method is discussed which examines trace, dried bloodstains by gel in situ hybridization using a Y-chromosome-specific deoxyribonucleic acid (DNA) probe to determine the sex of the bloodstain for forensic medicine application. The complete DNA is transferred directly by electrophoresis onto the gel intact, bypassing the possibilities of impurities contaminating the sample and of DNA degradation. The method has proven accurate for small (2.5-mm-diameter) samples aged up to eight years and is quick, simple, and easily read.

Adult↗
PubMed1989

[A carotid resection in cervical tumors without a vascular reconstruction].

From 1979 to 1988, 15 cases, consisting of 12 carotid body paragangliomas, 1 vagal body paraganglioma, 1 aneurysm of the internal carotid artery, and 1 recurrent metastatic carcinoma of the neck, were given a simple carotid resection without a vascular reconstruction, since the lesions were fixed to the carotid artery. The collateral cerebral cross-flow was promoted preoperatively with the use of compressing exercises of the carotid artery and controlled by computerized rheoencephalography. There was no operative mortality, though a transient postoperative cerebral complication did occur in one female patient, from which she recovered in one month. Of this series of 15 patients, one died from a malignant lesion and 14 survived for 3 months to 9 years without cerebrovascular complications.

Adolescent↗
PubMed1988

Construction of three plasmids, each containing two or three different human globin gene fragments.

Three plasmids (labeled pUC-2 gamma-beta, pUC-2 beta-delta, and pL-alpha-zeta), each containing two or three different human globin gene fragments (beta IVS-II, inter-gamma, and gamma IVS-II in pUC-2 gamma-beta; 5'-beta, 3'-beta, and delta IVS-II in pUC-2 beta-delta; alpha and zeta in pL-alpha-zeta) have been constructed. The gene fragments could be isolated simultaneously from Eco RI/Bam HI double digests of each of the first two plasmids or from a Pst I digest of the third, using electrophoresis in an 1.0% agarose gel. This facilitates the large-scale isolation of gene fragments for use as probes in studies such as the analysis of polymorphisms or the molecular basis of some hemoglobinopathies.

DNA↗
PubMed1988

Effects of dexamethasone on electroacupuncture analgesia and central nervous system metabolism.

Many reports have indicated that electro-acupuncture analgesia (EAA) was mediated by endorphins. Among them is B-endorphin which can be released from the anterior lobe of the pituitary. To examine the role of B-endorphin in EAA and observe CNS metabolic (functional) and behavioral effects of dexamethasone the present study employed the (14C) 2-deoxyglycose (2DG) method. Seventeen adult male Sprague-Dawley rats in five groups received the following different types of somesthetic stimulation to examine the local cerebral glucose utilization (LCGU) and tail-flick response latency: control group (N = 3), pain group (N = 4), EA group (N = 3), pain + EA group (N = 3; from another ongoing study) and dexamethasone group (N = 4). Dexamethasone reduced tail-flick response latency in response to electroacupuncture, and produced metabolic (functional) changes in a number of CNS structures implicated in electroacupuncture produced analgesia effects (some changes were statistically significant, many others were not). Specific brain structures exhibiting statistically significant changes (p less than 0.05) in LCGU when compared to the pain + EA group are: the parafascicular and habennlar nuclei of the thalamus and the posterior cingulate gyrus. In comparison of dexamethasone group with the other four experimental groups of rats, the following trend in LCGU changes was observed: pain + EA group greater than pain group = EA group = dexamethasone group greater than control group. In addition, dexamethasone had a sedative effect. The results suggest that dexamethasone is reducing EAA and having suppressive effects on CNS metabolism and behavior.

Acupuncture Therapy↗
PubMed1988

Four categories of gamma-globin gene triplications: DNA sequence comparison of low G gamma and high G gamma triplications.

The human fetal gamma chains are produced by closely linked G gamma and A gamma genes, and unequal crossing over between them leads to gamma gene deletions and triplications. Nine gamma gene triplications from seven ethnic groups were analyzed for G gamma and hemoglobin F (Hb F) values of heterozygotes and for the presence of polymorphic XmnI restriction sites 5' to the gamma genes. Four categories of triplication were found: I had low G gamma and low Hb F values and lacked XmnI sites 5' to the three gamma genes [---]. II had high G gamma and slightly elevated Hb F values but was also [---]. III was similar to II, except that XmnI was [+--]. IV had very high G gamma and slightly elevated Hb F values, and XmnI was [++-]. One case each of triplications I and IV were cloned into Charon 35. For both, the two 5' gamma gene code for G gamma chain, while the 3' gamma gene codes for A gamma chain. DNA sequencing showed that the unequal crossover occurred between 472 and 398 base pairs (bp) 5' to the gamma gene Cap sites (-472 and -398) for the type IV triplication and between -271 and codon 136 for the type I triplication. In addition, type I had a 4-bp deletion of AGCA from -225 to -222. The high G gamma values of the type IV triplication are explained by its -G gamma-G gamma-A gamma-gene arrangement and the XmnI sites 5' to the G gamma genes. We hypothesize that the low G gamma value of the type I triplication, which is also -G gamma-G gamma-A gamma-, is due to inactivation of the middle G gamma gene by the AGCA deletion at -225 to -222.

Adult↗
PubMed1987

The beta-delta crossover leading to the beta delta hybrid gene of hemoglobin P-Nilotic is located within 54 base-pairs of the 5' end of exon 2 or between codons 31 and 50.

The crossover region of the beta delta hybrid gene of the hemoglobin variant Hb P-Nilotic was defined in detail through cloning and sequencing of appropriate DNA segments. The crossover must have occurred without loss of bases within a 54 base-pair stretch of DNA between bases 275 and 330 (or between amino acid residues 31 and 50), indicating that the exon 1 and IVS-1 originate from beta, and exon 2, IVS-2 and exon 3 from delta. The data support the speculation that the IVS-1, in contrast to IVS-2, has no effect on the expression of this hybrid gene.

Adult↗
PubMed1987

Construction of two plasmids, each containing three different human globin gene fragments.

Two plasmids (labelled pUC-2 gamma-beta and pUC-2 beta-delta), each containing three different human globin gene fragments (gamma IVS-II, inter-gamma, and beta IVS-II in pUC-2 gamma-beta, and 5'-beta, 3'-beta, and delta IVS-II in pUC-2 beta-delta) have been constructed. The three gene fragments could be isolated simultaneously from Eco RI/Bam HI double digests of each of the two plasmids using electrophoresis in an 1.0% agarose gel. This facilitates the large-scale isolation of the gene fragments for use as probes in studies such as the analysis of beta-globin gene cluster polymorphisms or of the molecular basis of some hemoglobinopathies.

DNA, Recombinant↗
PubMed1986

Synthesis of a fixed-length single-stranded DNA probe by blocking primer extension in bacteriophage M13.

A simple and efficient technique has been developed for preparing radiolabeled single-stranded (ss) probes of determined length and high specific radioactivity. The human beta-globin gene intervening segment II (IVSII) fragment (0.9-kb) was inserted between the EcoRI and BamHI sites of M13mp11 and used as a template for ss probe synthesis. The M13 hybridization probe primer (M13 Hpp) was annealed to the recombinant M13mp11-beta IVSII template DNA. This M13 Hpp was next blocked by the enzymatic addition of a dideoxy adenosine monophosphate (ddAMP) residue to the 3' OH group of the primer. The M13 universal sequencing primer was then annealed and used to prepare an ss copy of the beta-IVSII fragment. Synthesis of the ss fragment was terminated by the presence of the dd-blocked M13 Hpp yielding a specific 0.9-kb ss beta-IVSII probe.

Cloning, Molecular↗