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Biomedical subjects

B Liu

Publications and source records attributed to B Liu.

At least 631 records · Page 35Linked to original sources

Preconcentration and determination of lead ions at a chitosan-modified glassy carbon electrode.

In this paper, the preparation of a chitosan-modified glassy carbon electrode (CMGCE), by the method of covalent-bond reaction, is described and the anodic stripping voltammetric characteristics of lead at a CMGCE are studied. The CMGCE can be used for the preconcentration and determination of trace amounts of lead(II) in water samples, and its sensitivity is about 14 times greater than that of an unmodified glassy carbon electrode. The selectivity, reproducibility and analytical results for water samples are satisfactory.

Chelating Agents↗

Modulatory effects of testosterone on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity.

In this experiment, we examined the modulatory effects of testosterone on the parkinsonism-inducing drug 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in two strains of mice. Orchidectomized male CD-1 and C57/B1 mice were implanted with either empty Silastic capsules or capsules containing testosterone and subsequently treated with MPTP. A small area of the corpus striatum was removed for determination of dopamine (DA) content, whereas the remainder was superfused and used to measure L-DOPA (5 microM)-evoked DA release. In animals treated with MPTP, L-DOPA-evoked DA release was reduced significantly in CD-1 mice, but not in C57/B1 mice, treated with testosterone. No differences in L-DOPA-stimulated DA release between MPTP-versus vehicle-treated mice was observed in either the CD-1 or C57/B1 mice receiving empty Silastic capsules. Corpus striatum DA contents were more severely depleted in the MPTP-sensitive C57/B1 versus the CD-1 mouse strain irrespective of hormone treatment. These results confirm previous results demonstrating differences in these two mouse strains in response to the neurotoxic effects of MPTP upon corpus striatum DA content. More interestingly, they show an important differential modulatory effect of testosterone upon L-DOPA-evoked DA release as a function of MPTP treatment and indicate that testosterone significantly alters the neurotoxic effects of MPTP in the CD-1 mouse.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

Low external K+ regulates Na,K-ATPase alpha 1 and beta 1 gene expression in rat cardiac myocytes.

Incubation of mammalian cells in medium containing low K+ is often associated with an increase in Na,K-ATPase activity and content. In the present studies, we investigated the effect of low K+ on the regulation of Na,K-ATPase alpha 1 and beta 1 gene expression in primary cultures of neonatal rat cardiac myocytes. Northern blot hybridization analysis indicated that exposure of cardiocytes to a medium containing 0.3 mmol/L K+ for 72 h resulted in 1.8- and 3.3-fold increases in the abundance of alpha 1 and beta 1 mRNAs, respectively, compared with control cells exposed to 5.4 mmol/L K+. To investigate the molecular mechanism of the low K effect on beta 1 mRNA content, we constructed chimeric genes with a full-length and deleted portion of the 5' end of the rat beta 1 gene linked to the firefly luciferase gene. Transient transfection experiments using these constructs indicated that beta 1 gene sequences between -102 and +151 base pairs (bp) are required for low K(+)-induced trans-activation of reporter gene expression. Taken together, these results indicate that low K+ induction of beta 1 mRNA abundance in neonatal rat cardiac myocytes is mediated by regulatory DNA sequences in close proximity to the site of transcription initiation of the beta 1 gene.

Animals↗

Target imbalance: disparity of Borrelia burgdorferi genetic material in synovial fluid from Lyme arthritis patients.

Lyme arthritis is a late manifestation of Lyme disease that results in episodic synovial inflammation and swelling. Although this process is thought to be driven directly by the spirochetal etiologic agent, Borrelia burgdorferi, the organism itself has been recovered by culture only twice. In contrast, polymerase chain reaction (PCR) studies are usually positive. This apparent discrepancy in 19 culture-negative synovial fluid specimens from 18 patients with Lyme arthritis was investigated. In all 19, DNA sequences characteristic of plasmid-encoded genes OspA and OspB were easily detected. However, despite equivalent or even superior analytic sensitivity for detection of cultured organisms, the reactivity of two genomic DNA targets was often weak or absent altogether in the clinical specimens. This apparent overrepresentation of B. burgdorferi plasmid sequences was found exclusively in clinical specimens and not in cultured organisms. The physiologic imbalance of genomic and plasmid DNA reactivity in B. burgdorferi infection may signal an underlying pathogenetic mechanism.

Antigens, Bacterial↗

Activation of phospholipase D in Chinese hamster ovary cells expressing platelet-activating factor receptor.

Platelet-activating factor (PAF) activated phospholipase D (PLD) in WT-H cells, CHO cells stably expressing cloned guinea-pig PAF receptor. The PLD activation was found to be dependent on extracellular Ca2+, protein kinase C (PKC), and a currently unidentified protein tyrosine kinase (PTK). PTK inhibitors ST-638 and genistein inhibited PLD activation induced by PAF as well as phorbol myristate acetate, indicating that PTK acts downstream of PKC. Furthermore, activation of MAP (mitogen-activated protein) kinases, as assessed by their phosphorylation, was also dependent on Ca2+, PKC, and PTK. The correlation between PLD activity and MAP kinase activation, together with the previously observed MAP kinase activation associated with arachidonic acid release by cPLA2 [Honda et al. (1994) J. Biol. Chem. 269, 2307-2315], led us to examine the involvement of MAP kinase in PLD activation. The results indicate that PLD and MAP kinases are activated through the common pathway consisting of Ca2+, PKC, and the unidentified PTK, which act in parallel, but not in a linear sequence.

Animals↗

A comparison of soft-tissue substitutes.

The fate of the Zyderm II, Zyplast, Vicryl, and chromic gut was histologically examined up to 1 year following subcutaneous implantation into rats. Our data demonstrated both Zyderm II and Zyplast to be inert materials without inflammatory response; there was no difference in long-term persistence between these two collagens. Both Vicryl and chromic gut implants caused an intense inflammatory response at 1 month, and Vicryl was completely resorbed before 6 months. The degree of inflammation associated with chromic gut diminished over time, and approximately 67% of the material persisted without reaction up to 1 year.

Animals↗

gamma-Tubulin in Arabidopsis: gene sequence, immunoblot, and immunofluorescence studies.

gamma-Tubulin is a protein associated with microtubule (Mt)-organizing centers in a variety of eukaryotic cells. Unfortunately, little is known about such centers in plants. Genomic and partial cDNA clones encoding two gamma-tubulins of Arabidopsis were isolated and sequenced. Comparisons of genomic and cDNA sequences showed that both genes, TubG1 and TubG2, contain nine introns at conserved locations. The sequences of the two genes both predict proteins containing 474 amino acids, with molecular masses of 53,250 and 53,280 D, respectively. The predicted gamma 1- and gamma 2-tubulins exhibit 98% amino acid identity with each other and approximately 70% amino acid identity with the gamma-tubulins of animals and fungi. RNA gel blot results demonstrated that both genes are transcribed in suspension culture cells, seedlings, and roots and flowers of mature plants. Immunoblots of Arabidopsis proteins using an antibody specific to a conserved peptide of gamma-tubulin showed a major cross-reacting polypeptide with an M(r) of 58,000. The same antibody stained all Mt arrays in tissue and suspension culture cells of this species. Binding was inhibited by the homologous oligopeptide in the gamma-tubulins predicted by the two Arabidopsis gene sequences. Antibody staining avoided the plus ends of Mts at the kinetochores and cell plate, but unlike the case in animal cells, seemed to be localized over broad stretches of the kinetochore fibers and phragmoplast toward the minus ends. We concluded that at least two gamma-tubulin protein homologs are present in Arabidopsis and that at least one of them is localized along Mt arrays. Its distribution is correlated with and may help explain unique characteristics of Mt organization in plants.

Amino Acid Sequence↗

Widespread expression of perlecan proteoglycan in basement membranes and extracellular matrices of human tissues as detected by a novel monoclonal antibody against domain III and by in situ hybridization.

Perlecan, a multidomain heparan sulfate proteoglycan (PG), is an intrinsic component of basement membranes and extracellular matrices. We used a prokaryotic expression vector to generate fusion proteins encoding various domains of human perlecan protein core and these recombinant proteins were used as immunogens to produce mouse anti-human monoclonal antibodies (MAb). One MAb, designated 7B5, was characterized by Western blotting and ELISA and was shown to react specifically with the laminin-like region of perlecan (Domain III) but not with two other fusion proteins encoding Domain II or V. This perlecan epitope was detected by immunoenzymatic staining in the basement membranes of human tissues including pituitary gland, skin, breast, thymus, prostate, colon, liver, pancreas, spleen, heart, and lung. All vascular basement membranes tested contained this gene product. In addition, sinusoidal vessels of liver, spleen, lymph nodes, and pituitary gland expressed high levels of perlecan in the subendothelial region. In situ hybridization, using as probe the same human cDNA-encoding Domain III, localized perlecan mRNA to specific cell types within the tissues and demonstrated that in skin, perlecan appears to be synthesized exclusively by connective tissue cells in the dermal layer. The availability of MAb against precise regions of human perlecan will allow the investigation of this gene product in normal and diseased states.

Animals↗

[Propagation of the HTV in primary human embryonic kidney and lung cell culture].

2 strains of Hantaan virus (HTV, 76-118, Hubei-114) have been propagated successfully in cultured primary human embryonic kidney (HEK) and lung (HEL) cells. Cytopathic effect (CPE) was observed in the two kind of cells on day 5 to 7 postinoculation which showed the cell became round and clustered, then detached. The replicating peak of the Hubei-114 in two kinds of cell cultures appeared on the 11th day and another strain on the 14th or 17th day after infection. The ultrastructure changes were observed with EM and IEM, which stained by ICGT before embedding. It was discovered that the mitochondia atrophied and decreased, and inclusion bodies in the cytoplasma of HEK and KEL cells. A large amount of gold granulae were found in the inclusion bodies and the virions were seen occasionally. Contamination with other agents have been ruled out. Our data suggest that the replicating characters of HTV in these cell systems might be possible for the pathogenicity of HFRS for human.

Cells, Cultured↗

[Digital subtraction angiography in otorhinolaryngology--preliminary report].

The paper presents the preliminary experience with digital subtraction angiography (DSA) in otorhinolaryngology. This series included racemose hemangioma of the auricle in 3 cases, juvenile angiofibroma of nasopharynx in 4 cases, angioma in the retropharyngeal space in 1 case, tympanic body tumor in 1 case, traumatic epistaxis in 1 case, traumatic pseudoaneurysm in 1 case. The site, supply arteries, drainage veins of vascular tumors were shown with DSA. The intraoperative bleeding was reduced significantly by preoperative embolization of supply arteries to vascular tumors. The broken arteries of the traumatic epistaxis and the traumatic pseudoaneurysm were not only discovered but embolized. The indications and complications of DSA and measures for preventing and reducing complications were discussed.

Adult↗

[Comparison of skeletal development between rural and urban school-age children].

Skeletal development and other related indicators were measured in 1680 children aged 7-18 in urban areas of Harbin and rural areas of Hailun County in 1990-1992, and comparisons were made. The results showed that the skeletal age of urban children aged 7-17 was higher than that of rural children in both sexes, and this difference was significant in the early puberty stage. The difference in mean values of cortical thickness of the metacarpals between urban and rural children showed similar tendency. Sesamoid ossification in urban children occurred one year earlier than that in rural children in both sexes. In primary school-age children, skeletal age was highly correlated with body height and weight. The development of secondary sex characteristics in both sexes and the age at menarche in girls in urban areas were earlier than those in rural areas, and the onset of puberty occurred one year earlier in urban than that in rural children.

Adolescent↗

[Experimental and clinical observation on wrinkle correction by medical cosmetic collagen injection].

Medical cosmetic collagen is a new biomaterial for soft tissue augmentation, such as wrinkle correction, It consists of highly purified human collagen. The ratio of type I and type III collagen is 44/56. The persistence of collagen in rats is more than one year. Rat cells and capillaries grew into the injections. Fibroblasts synthesized rat collagen. Capillaries established blood supply. The clinical observation on 123 cases proved the safety of this product. No adverse reactions developing from the use of the collagen were found. It was effective in correcting contour deformities of the skin. More than 90% correction results were excellent or good.

Adult↗

[ELISA for measurement of human serum apolipoprotein A II].

A specific, sensitive and simple ELISA for the measurement of human serum apo A II has been developed. The monospecific antibody was raised in goats. The polytyrene plates coated with purified anti-apo A II goat gamma-globulin together with enzyme labelled goat antibodies against human apo A II conjugate were used in this assay. The conjugate was obtained by binding horseradish perioidate by a simplified periodase method. No cross-reactivity with human apo A I, B100, C I, C II, C III and albumin was observed. The minimum measurable concentration of apo A II was 500ng in each assay. A standard curve with a working range of 0.25-8.0 mg/dl was plotted. The coefficients of variation of the reproducibility of intra- and interassays of apo A II in samples were 5.0-8.6% and 6.8-9.9% respectively. The recovery were 106.0 +/- 2.1% (n = 4). The mean concentrations of apo A II in 41 healthy subjects were 24.4 +/- 5.9mg/dl by our method and 26.7 +/- 4.6 mg/dl by RID method, respectively (r = 0.8000, P < 0.001).

Apolipoprotein A-II↗

[Effects of electroacupuncture on central and peripheral monoamine neurotransmitter in the course of protecting rat stress peptic ulcer].

The experimental Wistar rats were divided into two groups, the acupuncture group and the control group. Stress-induced gastric ulcer models were established by immersion of restrained rats in water. The results are as follows: 1. Stress-induced peptic ulceration was able to be protected with electroacupuncture. 2. Synthesis and decomposition of central and peripheral 5-HT in the electroacupunctured tats was inhibited. 3. The NE levels in the three brain regions (cortex, hypothalamus, brainstem) and blood were seen in the electroacupuncture group more than that in the control group, but the NE levels was smaller in the gastric tissue. 4. The higher levels of DA in the gastric tissue and blood were seen in the electroacupuncture group than in the control group. The results indicated that protecting rat stress ulceration with electroacupuncture was connected with monoamine neurotransmitter of centre and periphery.

Animals↗

[Pathological studies on alveolar hydatid in gerbils treated with albendazole and praziquantel].

Pathological changes in alveolar hydatids from experimentally infected gerbils were studied after administration of albendazole or praziquantel. The animals were divided into several groups including the control one, and drugs of different dosages were given separately to different groups with diverse durations of infection. According to the microscopical observation, the hydatids could be categorized into 3 grades: grade I, degenerated cysts; grade II, stable cysts (showing no proliferation); grade III, proliferated cysts. Larger proportion of grade I cysts were found in the group treated with albendazole at high dosage (33.3%) and the two groups treated with praziquantel (25.0% and 16.3%). The proportion of grade I cysts in gerbils with shorter duration (45 d) of infection was larger than those with longer duration (60 d). Lymphocyte infiltration to various extent was present surrounding the alveolar hydatid cysts in all the treated groups. More marked infiltration of lymphocytes was observed in albendazole treated gerbils (106.9 +/- 34.3-300.1 +/- 59.5) (P < 0.001). However, the combined medication of albendazole and praziquantel was less efficacious.

Albendazole↗

[Foreign genes expression in Wistar rats in vivo].

pN2-LacZ or pN2-CMV-ProUK plasmid DNA was separately injected into rat quadricept muscles and beta-galactosidase or Pro-UK was detected after 2 days. The expression of foreign genes lasted for at least 3 months. pN2-LacZ plasmid was injected into the left ventricular wall of the rat, and the expression of LacZ gene was more efficient than in the quadricept muscle. pN2-LacZ was also introduced into the rat arterial wall by balloon catheter. A new method was also found to improve the efficiency of foreign gene expression in muscle by stitching medical stitch containing plasmid DNA onto the quadricept muscle.

Animals↗

[Optimization of the processing technology of Aconitum kusnezoffii Reichb. by orthogonal test].

A study on the processing technology of Aconitum kusnezoffii by orthogonal test was carried out by assaying as criteria the changes in contents of the total alkaloids and ester type alkaloids before and after processing. The optimum experimental conditions were obtained after treating the experimental data with a formula for the multiple criteria, and the optimal processing results were achieved by having the material macerated with water, cut into thick pieces and then steamed under high pressure (127 degrees C, 0.15MPa) for 3 hours.

Alkaloids↗