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Biomedical subjects

H Zhu

Publications and source records attributed to H Zhu.

At least 289 records · Page 16Linked to original sources
PubMed1999

[Functional reconstruction of mandible by using vascularized fibular free flap and one-stage rehabilitation of the implant].

OBJECTIVE: To study the characteristics of the vascularized fibular free flap and the possibility of the insertion of implant at the same time. METHODS: The microvascular surgical procedure and implant technique were used in the treatment of two cases suffered from mandibular ameloblastoma. After tumor resection by partial mandiblectomy, graft of vascularized fibular free flap was performed with simultaneous insertion of 5 implant. RESULTS: One year later, the grafted bone was survival, the osseointegration was proceeded between the implant and grafted bone. The functional reconstruction of the mandible was excellent after prosthetic denture. CONCLUSION: This is a good approach to rehabilitate bone function by using vascularized fibular free flap and one-stage implant placement.

Adult↗
PubMed1999

[Analysis of MRI and CT manifestations of paranasal sinuses and orbitocranial disorders with secondary exophthalmos].

OBJECTIVE: To study the MRI and CT manifestations of paranasal sinuses and orbitocranial disorders with secondary exophthalmos. METHODS: MRI and CT scans of 51 patients were examined. RESULTS: MRI offers more information for evaluation of soft tissue lesions; the cavernous hemangioma and dermoid cyst were found to present rather characteristic images. Whereas in evaluation of lesions involving bony structures and calcifications, CT was superior to MRI. CONCLUSION: CT and MRI may evaluate the tumor location, extension into adjacent areas and are valuable in differential diagnosis of paranasal sinuses and orbitocranial disorder with secondary exophthalmos.

Adolescent↗
PubMed1999

[Change of high density lipoprotein receptor of hepatocyte during cholesterol gallstone formation in rabbit model].

In order to study the formation of cholesterol gallstone through rabbit model which was induced by high cholesterol diet (HCD), we investigated the high density lipoprotein receptor (HDLr) activities of hepatocytes, total bile acids and cholesterol of common duct bile at 1 week(1 w), 2 weeks(2 w), 3 weeks (3 w) and 4 weeks(4 w) in comparison with those of a control group respectively. The results were as follows: 1. The HDLr Bmax decreased and the kd value increased significantly (1 w group vs control group, P < 0.05); In 2 w group the two variables recovered to the level of control group; and after that, the HDLr Bmax increased and Kd value decreased markedly (3 w and 4 w groups vs control group, P < 0.05). 2. Total bile acids in bile increased slightly in 1 w group (vs control group, P > 0.05), then decreased in 2 w, 3 w and 4 w groups (4 w group vs control group, P < 0.05). 3. The concentration of cholesterol in bile increased gradually as the time of feeding HCD went on (3 w and 4 w groups vs control group, P < 0.05). The results demonstrated that owing to the intake of HCD with the passage of time, the activity of HDLr was up at the beginning and down gradually in the rest period. The change in concentrations of bile acids was similar to that of HDLr, and the concentration of cholesterol in bile was foreign to the change of HDLr. These results suggest that the decrease of HDLr activity may cause the absence of material for bile acids synthesis and it may play an important role in the formation of gallstone.

Animals↗
PubMed1999

[Spherical phenyl-regenerated cellulose stationary phases used for hydrophobic chromatography to extract bramelain from crude stem bramelain].

The low-pressure preparative hydrophobic chromatography packing materials have been successfully synthesized by grafting hydrophobic phenyl group to the macro-pore Spherical Regenerated Cellulose Resin (diameter 0.7-1.3 mm, pore size 4.3-15.7 microns, specific surface area 88 m2/g). The optimum adsorption-desorption conditions have been got by using 10 mL of this hydrophobic resin to deal with 100 mL of the crude stem bramelain: the mobile phase pH is around 5.0, concentration of (NH4)2SO4 is 1.5 mol/L; and the pH of total eluate is 8.0. While the hydrophobic column is operated according to the following steps: 1. use 0.1 mol/L NaAc-HAc(pH 4.8) and 1.5 mol/L (NH4)2SO4 solution to soak resin for more than 30 min; 2. let 100 mL of the extracted liquor of pineapple skin, which contains the same concentration of salt as 1, pass through the hydrophobic column; 3. use 20 mL of the same solution as 1 to wash the impurities in proteins, which are not adsorbed by the hydrophobic column; 4. use 30 mL of eluant, which contains 67 mmol/L NaOH and 50 mmol/L Na2CO3-NaHCO3(pH 10.28), to elute the adsorbed bramelain, and the initial 5 mL of the eluate is discarded; 5. soak the hydrophobic column with 0.5 mol/L NaOH + 20% (volume fraction) C2H5OH for 30 min, then wash it with water, and soak it with 0.5 mol/L HCl for 30 min, at last use water to wash it to neutrality for next use. We can get enriched bramelain of 4.4 fold activity, moreover the total enzyme activity recovery is more than 120%. The Phenyl-Spherical Regenerated Cellulose Resin can be used at the pH from 1 to 13; As it has a high rigidity and big size, it can be operated under low-pressure condition; It has a larger specific surface area and a higher separation efficiency for natural bramelain; After it has been used repeatedly for more than 50 times, its efficiency does not fall. Moreover, it is cheap to be produced.

Ananas↗
PubMed1999

[The characterization of a novel testis-specific nucleoporin gene].

OBJECTIVE: To investigate the structure and function of testis-specific gene and spermatogenesis in human. METHODS: Screening cDNA expression library, 5' rapid amplification of cDNA ends, Northern blot and fluorescent in situ hybridization(FISH) were used. Gene expressing, purified of expressed protein by affinity chromatography and SDS-PAGE as well as phosphorylation of expressed protein in vitro by PKC and p34cdc2 were observed. RESULTS: A cDNA designated as BS-63 was isolated and found to consist of 2,209 bp with an open reading frame of 2,100 bp and assigned the accession number U64675 by GenBank. The deduced polypeptide consisted of 700 amino acid residues containing XFXFG or FG motifs that were characteristic of nuclear pore complex (NPC) protein and acted as potential binding sites for Ran. The N-terminal region had high homology with Ran BP2/Nup 358, a nucleoporin component, showing that BS-63 was a member of the NPC family. Northern blot analysis of mRNA prepared from various human tissues showed that BS-63 gene was transcribed in two forms: 6.0 and 8.5 kb. The 8.5 kb transcript was present in low amounts in several somatic tissues; whereas the 6.0 kb transcript was expressed only in testis. Analysis by FISH method mapped the BS-63 gene in 2q11.2-12. A protein band with an estimated Mr of 80,000 was detected with E. coli BL21 (DE3) transfected with recombinant plasmid pET30a (+)-BS-63. In vitro phosphorylation test indicated the BS-63 recombinant protein could be phosphorylated by PKC and p34cdc2. CONCLUSIONS: The study was the first demonstration that the BS-63 gene encoding a nucleoporin-related protein with Ran binding sites was expressed in germ cells of human testis.

Amino Acid Sequence↗
PubMed1999

[The study on edge detection method of medical color image].

Considering the specificity of the medical color image, in this paper a medical color image is decomposed as three color orthogonal feature: I1, I2 and I3 in K-L transformation method, and Kirsch algorithm is used to detect the edge of the monochrome image I1 including rich information. Finally, both clarity edge and rich detail of color backdisplay image are gained, if we adopt I2 and I3 to compensate I1.

Algorithms↗
PubMed1999

[Determination of metals in atmospheric particulates by atomic absorption spectrometric method (AAS) with CA-CN micropore membrane filters used for sampling].

A new sampling method of atmospheric particulates using 0.22 microm pore diameter micropore membrane filters was introduced. Copper, lead, zinc cadmium, manganese, iron, nickel and chromium in atmospheric particulates were determined by atomic absorption spectrometry. This sampling method has shown several advantages: easy, complete and fast digestion; low membrane blank; increased flexibility to surrounding temperature change; high elution recovery, standard addition recovery, precision and accuracy.

Metals↗
PubMed1998

Cellular gene expression altered by human cytomegalovirus: global monitoring with oligonucleotide arrays.

Mechanistic insights to viral replication and pathogenesis generally have come from the analysis of viral gene products, either by studying their biochemical activities and interactions individually or by creating mutant viruses and analyzing their phenotype. Now it is possible to identify and catalog the host cell genes whose mRNA levels change in response to a pathogen. We have used DNA array technology to monitor the level of approximately 6,600 human mRNAs in uninfected as compared with human cytomegalovirus-infected cells. The level of 258 mRNAs changed by a factor of 4 or more before the onset of viral DNA replication. Several of these mRNAs encode gene products that might play key roles in virus-induced pathogenesis, identifying them as intriguing targets for further study.

Annexin A1↗
PubMed1998

Identification of a serine protease with nerve growth promoting activity from snake venom.

A new protein with nerve growth promoting activity was purified from the crude venom of the Agkistrodon halys Pallas, a Chinese snake. Its amino-terminal sequence unexpectedly showed high homology with serine proteases, suggesting that it is a new member of the serine protease family. It also cross-reacted with antibodies against thrombin-like enzyme and possessed weak arginine esterase activity, amounting to about 3% of the activity of trypsin. However, its nerve growth promoting activity was comparable to that of nerve growth factor (NGF). It was named NGF-like protease (NLP). Northern blot analysis further demonstrated different patterns of induction of c-myc, vgf and trkA mRNA transcription in PC12 pheochromocytoma cells treated with NGF and NLP, respectively. These data suggested that NLP represents a novel potent neurotrophic factor.

Agkistrodon↗
PubMed1998

Antipredictable sequences: harder to predict than random sequences.

For any discrete-state sequence prediction algorithm A, it is always possible, using an algorithm B no more complicated than A, to generate a sequence for which A's prediction is always wrong. For any prediction algorithm A and sequence x, there exists a sequence y no more complicated than x, such that if A performs better than random on x, then it will perform worse than random on y by the same margin. An example of a simple neural network predicting a bit sequence is used to illustrate this very general but not widely recognized phenomenon. This implies that any predictor with good performance must rely on some (usually implicitly) assumed prior distributions of the problem.

Algorithms↗
PubMed1998

Cleavage of BID by caspase 8 mediates the mitochondrial damage in the Fas pathway of apoptosis.

We report here that BID, a BH3 domain-containing proapoptotic Bcl2 family member, is a specific proximal substrate of Casp8 in the Fas apoptotic signaling pathway. While full-length BID is localized in cytosol, truncated BID (tBID) translocates to mitochondria and thus transduces apoptotic signals from cytoplasmic membrane to mitochondria. tBID induces first the clustering of mitochondria around the nuclei and release of cytochrome c independent of caspase activity, and then the loss of mitochondrial membrane potential, cell shrinkage, and nuclear condensation in a caspase-dependent fashion. Coexpression of BclxL inhibits all the apoptotic changes induced by tBID. Our results indicate that BID is a mediator of mitochondrial damage induced by Casp8.

Animals↗
PubMed1998

Deletion of the conserved first 18 N-terminal amino acid residues in rat liver carnitine palmitoyltransferase I abolishes malonyl-CoA sensitivity and binding.

To assess the role of the 130 N-terminal amino acid residues of rat liver carnitine palmitoyltransferase I (L-CPTI) on malonyl-CoA sensitivity and binding, we constructed a series of mutants with deletions of the 18, 35, 52, 73, 83, or 129 most N-terminal amino acid residues. The deletion mutants were expressed in the yeast Pichia pastoris. We determined the effects of these mutations on L-CPTI activity, malonyl-CoA sensitivity, and binding in isolated mitochondria prepared from the yeast strains expressing the wild-type and deletion mutants. The mutant protein that lacked the first 18 N-terminal amino acid residues, Delta18, had activity and kinetic properties similar to wild-type L-CPTI, but it was almost completely insensitive to malonyl-CoA inhibition (I50 = 380 microM versus 2.0 microM). In addition, loss of malonyl-CoA sensitivity in Delta18 was accompanied by a 70-fold decrease in affinity for malonyl CoA (KD = 70 nM versus 1.1 nM) compared to wild-type L-CPTI. Deletion of the first 35, 52, 73, and 83 N-terminal amino acid residues had a similar effect on malonyl-CoA sensitivity as did the 18-residue deletion mutant, and there was a progressive reduction in the affinity for malonyl-CoA binding. By contrast, deletion of the first 129 N-terminal amino acid residues resulted in the synthesis of an inactive protein. To our knowledge, this is the first report to demonstrate a critical role for these perfectly conserved first 18 N-terminal amino acid residues of L-CPTI in malonyl-CoA sensitivity and binding.

Amino Acid Sequence↗
PubMed1998

NMDA-R1 antisense oligonucleotide attenuates withdrawal signs from morphine.

To test the involvement of NMDA receptor in the development of physical dependence on opioid, the effects of an antisense oligonucleotide against NMDA receptors on the naloxone precipitated withdrawal from morphine were studied. Antisense oligonucleotide (15 nmol/5 microl) corresponding to the nucleotides 4-21 of rat NMDA-RI subunit, sense oligonucleotide, or saline was injected into the lateral ventricle of rats every 12 h for 6 days. On day 4, the rats were intracerebroventricularly (i.c.v.) infused with morphine (26 nmol microl(-1) h(-1)) through osmotic minipumps. Rats then received simultaneous treatment with morphine and oligonucleotides or saline for 3 days. Antisense oligonucleotide, but not saline or sense oligonucleotide, significantly attenuated naloxone precipitated withdrawal signs including jumping, rearing, stretching, teeth chattering, vocalization, and penis licking. Treatment with antisense oligonucleotide, but not sense oligonucleotide, significantly reduced the Bmax of [3H]MK801 ¿[3-3H](+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d)cyclohepten-5,10- imine¿ binding without significant changes in Kd. These results support the hypothesis that NMDA receptors are involved in the physical dependence on opioid.

Animals↗
PubMed1998

CD44 isoform-cytoskeleton interaction in oncogenic signaling and tumor progression.

CD44, a major hyaluronan receptor, exists as several isoforms and is widely distributed in different cells and tissues. The isoforms of CD44, such as CD44s (the standard form), CD44E (the epithelial form) and CD44v (variant isoforms) (arise from differential splicing of one to ten (or eleven) variable exons that encode portions of the membrane proximal extracellular domain. The molecular diversity of CD44 isoforms is further compounded by differential biosynthetic processes and post-translational modifications [e.g. N-/O-glycosylation or glycosaminoglycan (GAG) addition]. This structural arrangement, which occurs within either the invariant region or the extracellular domain of the variant region, is important for CD44-mediated communication between extracellular matrix materials [ECM-hyaluronic acid (HA), collagen and fibronectin] and intracellular protein components (e.g cytoskeletal proteins and various regulatory enzymes). The 15 amino acid sequence [e.g. NSGNGAVEDRKPSGL (in human) or NGGNGTVEDRKPSEL (in mouse)] residing in the cytoplasmic domain of CD44 isoforms is the ankyrin-binding domain of this family of transmembrane glycoproteins. Biochemical analyses plus in vitro mutagenesis indicate that the ankyrin-binding domain is required for CD44-mediated "outside-in" and "inside-out" cell activation events. Furthermore, CD44s-cytoskeleton interaction is tightly coupled with signal transducing molecules (e.g. p185HER2 or Src kinases) during oncogenic signaling. Moreover, the transmembrane linkage between CD44v isoforms (CD44v10 and CD44v3) and the cytoskeleton up-regulates invasive and metastatic-specific tumor phenotypes [e.g. matrix degradation (MMPs) activities, tumor cell invasion and migration]. These findings strongly suggest that the interaction between CD44 isoforms and the cytoskeleton plays a pivotal role in the onset of oncogenesis and tumor progression.

Animals↗
PubMed1998

Dissociation of phagocyte recognition of cells undergoing apoptosis from other features of the apoptotic program.

Apoptosis is a programmed form of cell death characterized by biochemical and morphological changes affecting the nucleus, cytoplasm, and plasma membrane. These changes in various cellular compartments are widely regarded as mechanistically linked events in a single "program" in which activation of caspases and proteolysis of intracellular substrates represent a final common pathway leading to cell death. To date there has been very limited exploration of the linkage of this program to the plasma membrane changes, which bring about swift recognition, uptake, and safe degradation of apoptotic cells by phagocytes. Using the mitochondrial inhibitors antimycin A and oligomycin in human monocytic THP.1 cells triggered into apoptosis, we report the uncoupling of plasma membrane changes from other features of apoptosis. These inhibitors blocked increased plasma membrane permeability, externalization of phosphatidylserine, and recognition by two classes of phagocytes but not activation of caspase-3, cleavage of poly(ADP-ribose) polymerase and DNA fragmentation. Externalization of phosphatidylserine in apoptotic human leukemic U937 cells was also dissociated from caspase activation. Thus changes governing safe clearance of apoptotic cells may be regulated by an independent pathway to those bringing about caspase activation. This finding could have important consequences for attempts to manipulate cell death for therapeutic gain in vivo.

Amino Acid Chloromethyl Ketones↗