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Biomedical subjects

Z Hu

Publications and source records attributed to Z Hu.

At least 199 records · Page 11Linked to original sources
PubMed1999

[Studies on pharmacological junctions of hairy root of Astragalus membranaceus].

OBJECTIVE: To investigate the effect of hairy root of Astragalus membranaceus(HRA). METHOD: HRA were given 10 g/kg per day for 50 days to aged mice treated with D-galactose, and the effect on memory and antioxidant functions were estimated. After administration of HRA 10 g/kg for four days, anti-ischemia-reperfusion kidney model of rat was prepared. The kidney function, activity of superoxide dismutase (SOD) and content of malondialdehyde(MDA) in kidney were examined. Mice with immunosuppression induced by cyclophosphamide were given orally HRA 10 g/kg for 12 days. The activity of natural killer (NK) cells was measured. RESULT: HRA improved the memory, raised SOD activity in brain and liver, decreased the MDA content in the liver of aged mice, reduced the MDA content in ischemia-reperfusion kidney, decreased the creatinine level in blood of rats, and promoted the activity of NK cells in immunosuppressed mice. CONCLUSION: Similar to the natural A. membranaceus, HRA has senility-preventing, antioxidizing and immunomodulating functions.

Aging↗
PubMed1999

[Biological characteristics and damaging regularities of grubs endangering the growth of Ophiopogen japonicus (Thunb.) Ker-Gawl].

OBJECTIVE: To provide a scientific basis for prevention and control of the damage done to Ophiopogen japonicus by grubs. METHOD: Conducting laboratory observation along with field investigation. RESULT: The grubs endangering the growth of O. japonicus are mainly Hoplosternus incanus, Holotrichina paraullela and Anomala corpulenta, H. incanus takes two years to make a generation and overwinters in the form of second or third-instar larvae. H. parallela and A. corpulenta generate yearly and overwinter in the form of third-instar larvae. The extent of the damage done to O. japonicus by grubs is related to such factors as the number of sequential cropping years, the model of intercropping and the type of soil. CONCLUSION: Prevention and control of the pest grub should be based primarily on proper agricultural (cultivating) measures.

Animals↗
PubMed1999

[Investigating the phenomenon of total erythrocyte destruction during an in-vitro hemolysis test by roller pump].

This study sought to address the question, "will the phenomenon of 'total erythrocyte destruction' come about during a long time of in vitro hemolysis test by roller pump". One-day-old boving blood was employed in the test by Polystan pump(group A) and Cobe pump (group B). TMB method was used to measure the level of plasma-free hemoglobin. The samples of plasma-free hemoglobin were taken at the time before pumping and pumping for 4,6,8,10, 12,14 and 16 hours. The index of hemolysis was calculated according to Koller's formula. The results showed that the levels of plasma-free hemoglobin in the two groups both increased linearly during the puming of blood. The index of hemolysis was 0.2960 mg/L group A, and 0.3993 mg/L in group B; no statistically significant difference was noted between the two groups. These data indicated that no phenomenon of "total erythrocyte destruction" was observed in this hemolysis test by roller pump.

Erythrocytes↗
PubMed1999

[Using lux genes marker technique to track Pseudomonas chlororaphis PL9L in cotton rhizosphere].

Tn7-luxCDABE marker system was successfully transferred into Pseudomonas chlororaphis (strain PL9) by means of transformation and conjugation and a stable lux-marked strain PL9L was obtained. The colonizing dynamics and distribution of the luminescent bacteria PL9L in the rhizosphere of cotton planted in pots and rhizoboxes were studied by the methods of X-ray film imaging and enumeration of luminescent colonies on agar media, The results of pot culture experiment showed that PL9L successfully colonized in the rhizosphere of cotton. In pot cultures of sterile soil the highest colonizing level(3.1 x 10(2) cfu/g root soil) was reached on 6th day after seeds sown; On 56th day, the population of PL9L tended to stable and decreased to 1.7 x 10(9) cfu/g root soil) but in pot cultures of unsterile soil, the highest colonizing level(1.1 x 10(9) cfu/g root soil) was reached on 8th day. On 46th day, the population of PL9L tended to a stationary state, the numbers of them were 1.4 x 10(2) cfu/g root soil. The results of rhizobox culture experiment showed that PL9L spread from seeds toward the direction of root tip, but not synchronized with the stretch of roots. 6 days after seeds sown, in rhizobox culture of sterile soil, PL9L spread 12.0 cm below seeds, but in non-sterile soil was 11.0 cm. In the region of cotton root tip, PL9L were not detected.

Bacterial Proteins↗
PubMed1999

[Analyses of central serous chorioretinopathy from indocyanine green angiography].

PURPOSE: To compare and analyse the characters of Indocyanine Green Angiography (ICGA) and Fundus Fluorescein Angiography (FFA) in Central Serous Chorioretinopathy (CSCR) and explore its pathological significance. METHOD: 35 cases of CSCR were examed with Heidelberg Retina Angiography. Simultaneous images of ICGA and FFA were analysed. RESULTS: Among the 35 cases, 29(83%) revealed more lesions in ICGA than in FFA. The lesions appeared in FFA were all associated with ICGA changes. CONCLUSION: The increasing of choroid hyperpermeability is an early change, which causes the overlying RPE dysfunction and structural damage. Some points related to the laser and medical treatment to CSCR were also discussed.

Angiography↗
PubMed1999

[Establishment of a method for classification of HBV genome and it's application].

OBJECTIVE: By using the techniques of PCR and restriction fragment length polymorphism (RFLP), we established a classification method for HBV genome based on viral S gene of asymptomatic HBV carriers (AsC). METHODS: By using this method we classified HBV DNA of AsC living in Guangzhou, Shenyang, Beijing and Chongqing. RESULTS: Among the AsC of Guangzhou, genotype B was 32.8%, genotype C 42.7%, mixed genotypes B and C 23.0%, others 1.6%; among the AsC of Chongqing, genotype B was 35.0%, genotype C 40.0%, mixed genotypes B and C 25.0%; among the AsC of Beijing, genotype B was 25.0%, genotype C 50.0%, mixed genotypes B and C 25.0%; among the AsC of Shenyang, genotype B was 11.1%, genotype C 88.9%. The prevalent HBV strains in China are genotype C and genotype B, and genotype C is the main genotype in west China. CONCLUSION: The established method for genotyping is simple and convenient. Using this method, we also classified HBV DNA of the patients with chronic hepatitis B and liver cirrhosis living in Guangzhou, and found that mixed genotypes B and C was in 50.0% of the patients detected, suggesting the mixed infection might lead to a severe damage of the liver tissue.

Carrier State↗
PubMed1999

[Experimental study of the properties of two-order FADOF at Cs 455 nm line under Nd:YAG pulse laser condition].

This paper experimentally studied some important properties of two-order FADOF at Cs 455 nm line under Nd:YAG pulse laser condition. At a selected temperature the properties of both the bandwidth and the transmission related to the magnetic field have been obtained. In this study, the bandwidth of two-order FADOF was increased linearly with the increment of the magnetic field from 200 to 700 Gauss and is obviously narrower than that of the two single-order FADOFs. The transmission of two-order FADOF was also linearly increased with the increment of the magnetic field in the same range and is lower than that of the single FADOF. Fortunately, at a slightly higher cell temperature, such as T = 160 degrees C, the transmission of two-order FADOF can reach 40%. Furthermore, it can reach theoretically up to 80% because 90% can be obtained in the case of single FADOF. The most important result in the study is that the out-of-bandwidth rejection, which is one of the three parameters, was improved from 10(-3) to 10(-5). The structure of the two-order FADOF is relatively simpler than that of the single-order FADOF.

English Abstract↗
PubMed1998

New preparation method of intestinal pressure-controlled colon delivery capsules by coating machine and evaluation in beagle dogs.

A new method for preparing large amounts of pressure-controlled colon delivery capsules (PCDCs) which employs a pharmaceutical coating machine, Hicoater-mini, has been developed. In contrast to our original method for preparing PCDCs where the inner surfaces of gelatin capsule were coated with the water-insoluble polymer ethylcellulose (EC), PCDC were directly prepared by coating the capsular shaped suppositories with EC. As a model drug, fluorescein (FL) was used in this study. FL powder was suspended with the suppository base, polyethylene glycol (PEG) 1000, at 50 degreesC, and was hardened in the capsular shape the sizes of which were #0 and #2. The capsular shaped suppositories were coated with 5% w/v ethanolic EC (7G grade) solution by a coating machine. By increasing the coating time from 55 to 75 min, the mean coating thickness of #0 PCDCs increased from 141+/-7 to 211+/-4 micrometer. In the case of #2 PDDCs, the mean coating thickness increased from 102+/-3 to 110+/-5 micrometer by increasing the coating time from 35 min to 40 min. Several kinds of #0 PCDCs having the mean EC coating membrane thickness of 141+/-7 micrometer (type 1), 166+/-4 micrometer (type 2), 188+/-4 micrometer (type 3), 211+/-4 micrometer (type 4) as well as #2 PCDCs having thickness of 102+/-3 micrometer (type 5) and 110+/-5 micrometer (type 6) were used for in vivo evaluation using beagle dogs. After oral administration of the test preparations containing 30 mg of FL, blood samples were obtained from the jugular vein and plasma FL levels were measured. The first appearance time, Ti, of FL in the plasma was used as a parameter for the estimation of the release time of FL from PCDCs in the gastrointestinal tract. The mean Ti of #0 PCDCs were 2.3+/-0.5 for type 1, 3.3+/-0.5 for type 2, 4.8+/-1.0 for type 3 and 7.8+/-1.7 h for type 4 preparations while the mean Ti of #2 PCDCs were 3.2+/-0.4 for type 5 and 3.8+/-0.4 h for type 6, respectively. There were good correlations between EC coatings.

Animals↗
PubMed1998

Protein trans-splicing by a split intein encoded in a split DnaE gene of Synechocystis sp. PCC6803.

A split intein capable of protein trans-splicing is identified in a DnaE protein of the cyanobacterium Synechocystis sp. strain PCC6803. The N- and C-terminal halves of DnaE (catalytic subunit alpha of DNA polymerase III) are encoded by two separate genes, dnaE-n and dnaE-c, respectively. These two genes are located 745,226 bp apart in the genome and on opposite DNA strands. The dnaE-n product consists of a N-extein sequence followed by a 123-aa intein sequence, whereas the dnaE-c product consists of a 36-aa intein sequence followed by a C-extein sequence. The N- and C-extein sequences together reconstitute a complete DnaE sequence that is interrupted by the intein sequences inside the beta- and tau-binding domains. The two intein sequences together reconstitute a split mini-intein that not only has intein-like sequence features but also exhibited protein trans-splicing activity when tested in Escherichia coli cells.

Amino Acid Sequence↗
PubMed1998

Direct Observation of Polymer Network Structure in Macroporous N-Isopropylacrylamide Gel by Raman Microscopy.

The Raman microscopy technique is used to characterize the temperature-induced evolution of the pore structures of a macroporous N-isopropylacrylamide (NIPA). The gel is synthesized using a suspension of 45 wt % toluene and 55 wt % pregel NIPA solution. The intensity of the band due to the CH2 bending vibration, centered at 1445 cm-1, is used to monitor the distribution of the polymer chain density in the lateral plane. It is found that the macroporous gel consists of water-rich areas, which can be interpreted as the pores, and polymer-rich areas. At room temperature, the average sizes of the pores and the width of polymer-rich areas are 75 µm and 20 µm, respectively. Both the pores and their surrounding polymer-rich areas have random geometry, as demonstrated by the Raman microimaging. With increased temperature the size of the pores decreases. This process is accompanied by a narrowing of the polymer-rich areas. At higher temperatures polymer chains bunch together and this process accelerates rapidly near the volume phase transition temperature (34 degreesC). Above 36 degreesC, the pore sizes become too small to be resolved using Raman microscopy.

Journal Article↗
PubMed1998

Cloning and expression of a group IV cytosolic Ca2+-dependent phospholipase A2 from rat pancreatic islets. Comparison of the expressed activity with that of an islet group VI cytosolic Ca2+-independent phospholipase A2.

Stimulation of pancreatic islets with glucose induces phospholipid hydrolysis and accumulation of nonesterified arachidonic acid, which may play signaling or effector roles in insulin secretion. Of enzymes that catalyze phospholipid hydrolysis, islet beta-cells express low molecular weight secretory phospholipases A2 (PLA2) and a Group VI, Ca2+-independent PLA2 (iPLA2). Previous studies indicate that islets also express a protein recognized by antibodies against a Group IV, cytosolic, Ca2+-dependent PLA2 (cPLA2). To further examine the possible expression of cPLA2 by islets, we screened a rat islet cDNA library with a probe that recognizes cPLA2 sequence, and isolated a full-length cPLA2 cDNA. The rat islet cPLA2-deduced amino acid sequence is 96% identical to those of human and mouse cPLA2. Transfection of COS-7 cells with cPLA2 cDNA in an expression vector induced expression of Ca2+-dependent PLA2 activity and of a protein recognized by anti-cPLA2 antibody. Comparison of recombinant islet cPLA2 and iPLA2 activities expressed in transfected COS-7 cells indicated that iPLA2 but not cPLA2 is stimulated by ATP. Both activities are similarly sensitive to inhibition by arachidonyltrifluoromethyl ketone, but iPLA2 is more effectively inhibited by a haloenol lactone suicide substrate than cPLA2. RT-PCR experiments with RNA from purified islet beta-cells and from an alpha-cell-enriched population prepared by fluorescence-activated cell-sorting indicated that cPLA2 mRNA is more abundant in the beta-cell population. Immunoblotting analyses indicate that islets express cPLA2-immunoreactive protein, and that interleukin-1 does not affect its expression. The cPLA2 is thus one of at least three classes of PLA2 enzymes with distinct properties expressed in beta-cells.

Amino Acid Sequence↗
PubMed1998

A topA intein in Pyrococcus furiosus and its relatedness to the r-gyr intein of Methanococcus jannaschii.

A new intein coding sequence was found in a topA (DNA topoisomerase I) gene by cloning and sequencing this gene from the hyperthermophilic Archaeon Pyrococcus furiosus. The predicted Pfu topA intein sequence is 373 amino acids long and located two residues away from the catalytic tyrosine of the topoisomerase. It contains putative intein sequence blocks (C, E, and H) associated with intein endonuclease activity, in addition to intein sequence blocks (A, B, F, and G) that are necessary for protein splicing. This DNA topoisomerase I intein is most related to a reverse gyrase intein from the methanogenic Archaeon Methanococcus jannaschii. These two inteins share 31% amino acid sequence identity and, more importantly, have the same insertion sites in their respective host proteins. It is suggested that these two inteins are homologous inteins present in structurally related, but functionally distinct, proteins, with implications on intein evolution and intein homing.

Amino Acid Sequence↗
PubMed1998

Beta3 integrins are upregulated after vascular injury and modulate thrombospondin- and thrombin-induced proliferation of cultured smooth muscle cells.

BACKGROUND: Treatment with an antibody that binds beta3 integrins (abciximab; c7E3 Fab) at the time of coronary angioplasty decreases the need for repeat revascularization. Two potential mechanisms have been proposed to explain this effect: (1) inhibition of platelet aggregation or (2) interruption of ligand binding to beta3 integrins on the smooth muscle cell (SMC) surface. We examined the latter hypothesis by determining (1) if beta3 integrin expression is upregulated after vascular injury in the baboon, (2) if 7E3 binds beta3 integrins on cultured SMC, and (3) if beta3 integrin activation plays a role in proliferation of cultured SMC. METHODS AND RESULTS: Results demonstrated that immunostaining for beta3 integrins was present in the neointima 1 week after balloon withdrawal injury of baboon brachial arteries and that beta3 integrin expression colocalized with alpha-actin-positive cells. In contrast, staining for beta3 integrins was undetectable in contralateral uninjured brachial arteries. 7E3 bound to cultured human aortic SMC with an affinity (KD=3.3 nmol/L) similar to 7E3 binding to endothelial cells or platelets. Cotreatment with 7E3 partially inhibited thrombospondin-induced or alpha-thrombin-induced proliferation but not PDGF-induced or serum-induced proliferation. CONCLUSIONS: In summary, these studies demonstrate that vascular cell beta3 integrin expression is increased after injury, that 7E3 binds to cultured SMC with high affinity, and that beta3 activation is important for thrombospondin-induced or alpha-thrombin-induced proliferation. These results support the hypothesis that beta3 integrins play a role in SMC growth responses after balloon injury.

Abciximab↗
PubMed1998

Evaluation of intestinal pressure-controlled colon delivery capsule containing caffeine as a model drug in human volunteers.

The delivery ability of a pressure-controlled colon delivery capsule (PCDC) containing caffeine as a test drug was evaluated after oral administration to healthy male human volunteers. The driving force causing PCDC disintegration in the intestinal tract is the physiological luminal pressure which results from peristalsis. Three kinds of PCDCs having different thickness of a water-insoluble polymer membrane was prepared by coating the inner surface of the gelatin capsules with ethylcellulose (EC). The mean thickness were 40 +/- 1 (SE) for type 1, 44 +/- 1 for type 2 and 50 +/- 1 micron for type 3 PCDC, respectively. Caffeine was dissolved with a suppository base (PEGs 400 and 1000) and the capsules were filled. Doses were 15, 45 or 75 mg. After blank saliva samples were obtained, test preparations were orally administered to the volunteers and saliva samples were collected for 1 min intervals hourly from 1 to 10 h in the fasted state study, and from 1 to 20 h and at 25 h in the fed state study. Caffeine concentrations in the saliva samples were analyzed by HPLC. The maximum salivary caffeine excretion rate increased as the oral caffeine dose increased. The maximum salivary caffeine excretion rate increased predominantly compared to the pre-dose level in 75 mg dose study. Therefore, all following studies were performed with this dose. The first appearance time of caffeine into the saliva, TI, was used as a parameter to estimate the disintegration time of test preparations in the gastrointestinal tract. The mean TI of types 1, 2, and 3 PCDCs were 3.0 +/- 0.4, 4.0 +/- 0.4 and 4.5 +/- 0.3 h, respectively. After oral administration of 75 mg caffeine in pain gelatin capsule as a reference preparation, caffeine appeared in the saliva within 0.5 h. The mean hardness of the PCDCs were 1.05 +/- 0.10 (type 1), 1.55 +/- 0.06 (type 2) and 2.08 +/- 0.15 newton (type 3), respectively. There were good correlations between three parameters: EC coating membrane thickness, hardness and TI (determination coefficient r2 = 0.935 between TI and thickness, r2 = 0.998 between thickness and hardness, r2 = 0.958 between hardness and TI). The effect of food intake on the delivery ability was examined with type 3 PCDCs. Food intake prolonged the mean TI, from 4.5 +/- 0.3 to 7.8 +/- 1.3 h. This increase is thought to be ascribed to prolonged gastric emptying time. Comparison with reported colon arrival times indicates that the type 3 PCDC functions in colon delivery of caffeine and is thought to be applicable to other drugs.

Adult↗
PubMed1998

Design and synthesis of monocyclic beta-lactams as mechanism-based inhibitors of human cytomegalovirus protease.

Mechanism based inhibitors of HCMV protease have been designed based on the monocyclic beta-lactam nucleus, which have been shown to acylate the viral enzyme in a time dependent manner. SAR in a series of monocyclic beta-lactam N-ureas, has defined the size and relative stereochemistry of the C-3 substituent producing a low micromolar inhibitor 17b with good aqueous stability and selectivity over the mammalian serine proteases.

Drug Stability↗
PubMed1998

Prenatal expression of inwardly rectifying potassium channel mRNA (Kir4.1) in rat brain.

The levels and cellular localization of the mRNA encoding the inwardly rectifying potassium ion channel Kir4.1 were investigated in the embryonic rat brain by Northern blots and in situ hybridization. This transcript was absent at embryonic day 13 (E13), whereas it was clearly present in E14-15 preparations, principally in the neuroepithelium of the cerebral cortex, thalamus, and hypothalamus. At later embryonic stages (E17-20), Kir4.1 mRNA levels increased and expanded to the mantle zone, such as the cortical plate, hippocampus, thalamus, and hypothalamus. The early appearance of Kir4.1 mRNA in various brain regions suggests an involvement of the channel in cell proliferation, migration and differentiation in the rat CNS.

Animals↗
PubMed1998

Crystallization and preliminary crystallographic analyses of pokeweed antiviral protein from seeds.

Pokeweed antiviral protein from seeds (PAP-S) is a ribosome inactivating protein which has lowest toxicity and highest inhibition activity as opposed to other pokeweed antiviral proteins and its three potential glycosylation sites (10, 44, 255) were shown to bind to N-acetylglucosamine. Good quality crystals of PAP-S were grown at high protein concentration (100 mg ml-1) and high temperature (306 K). The crystals have space group I222 and cell parameters a = 78.7, b = 85.2 and c = 93.0 A. An X-ray diffraction data set with resolution up to 1.8 A was collected. This high-resolution data will help to locate the sugars bound to the protein and provide accurate structural data for understanding structure-function relationships of PAP-S.

Antiviral Agents↗