Biomedical subjects

H Liao

Publications and source records attributed to H Liao.

At least 19 recordsLinked to original sources

PubMed2002

Facial subdermal vascular network flap: anatomic study and clinical application.

Despite the numerous flaps for facial reconstruction that have been described, the search for the ideal flap with good color matching and minimal donor-site morbidity continues. In the past 3 years we have repaired 13 facial defects with success using the lateral genicervical flap - a type of facial subdermal vascular network flap (SVNF) - with a pedicle located on the preauricular region. An anatomic study of the facial SVNF, including blood supply and vascular distribution of the face and anatomic characteristics of facial vessels, based on 14 cadaver dissections, was carried out. The blood supply of the facial skin basically originated from the branches of the facial, superficial temporal and infraorbital arteries. The lateral genicervical skin was supplied basically by the branches of the facial, superficial temporal and occipital arteries, but also by the terminal branches of the superior thyroid artery. The branches diverging from these arteries became superficial and formed a subcutaneous arterial network. The arterioles from the network went to the corium layer and formed a subdermal arterial network whose arterioles anastomosed with each other in a honeycomb-like structure. The vascular distribution presented certain directivity on different areas. The blood supply of the pedicle originated from the subdermal vascular network formed by the perforator branches of these arteries. The arterioles from the facial and superficial temporal arteries anastomosed in the lateral genicervical region. From the anatomic study, we think that the viability of the facial SVNF depends basically on the subdermal vascular network formed by the perforator branches of the pedicle, and that the anastomoses between the facial and superficial temporal arteries provide a solid anatomic basis to the lateral genicervical flap. The clinical data also indicated that this flap is a useful alternative for facial, especially superficial temporal, defects. But the directivity must be taken into account in its clinical application.

Adolescent↗

PubMed2001

Induction of a major leaf acid phosphatase does not confer adaptation to low phosphorus availability in common bean.

Acid phosphatase is believed to be important for phosphorus scavenging and remobilization in plants, but its role in plant adaptation to low phosphorus availability has not been critically evaluated. To address this issue, we compared acid phosphatase activity (APA) in leaves of common bean (Phaseolus vulgaris) in a phosphorus-inefficient genotype (DOR364), a phosphorus-efficient genotype (G19833), and their F(5.10) recombinant inbred lines (RILs). Phosphorus deficiency substantially increased leaf APA, but APA was much higher and more responsive to phosphorus availability in DOR364 than in G19833. Leaf APA segregated in the RILs, with two discrete groups having either high (mean = 1.71 micromol/mg protein/min) or low (0.36 micromol/mg protein/min) activity. A chi-square test indicated that the observed difference might be controlled by a single gene. Non-denaturing protein electrophoresis revealed that there are four visible isoforms responsible for total APA in common bean, and that the difference in APA between contrasting genotypes could be attributed to the existence of a single major isoform. Qualitative mapping of the APA trait and quantitative trait loci analysis with molecular markers indicated that a major gene contributing to APA is located on linkage group B03 of the unified common bean map. This locus was not associated with loci conferring phosphorus acquisition efficiency or phosphorus use efficiency. RILs contrasting for APA had similar phosphorus pools in old and young leaves under phosphorus stress, arguing against a role for APA in phosphorus remobilization. Our results do not support a major role for leaf APA induction in regulating plant adaptation to phosphorus deficiency.

Acid Phosphatase↗

PubMed2001

LDL-activated p38 in endothelial cells is mediated by Ras.

Endothelial dysfunction is a major atherogenic proinflammatory event. LDL causes the activation and phenotypic changes of cultured vascular endothelial cells (ECs). We previously reported that LDL activates c-Jun and AP-1 in ECs. In this study, we demonstrated that p38-ATF-2 is activated by LDL in human ECs and that this activation is mediated by Ras. When ECs are incubated with LDL in pathophysiological concentrations, the p38-mediated ATF-2 phosphorylation and ATF-2 transactivation are increased in a time- and dose-dependent manner. To elucidate the upstream mechanism in LDL-activated p38 in ECs, we demonstrate that LDL increases Ras translocation from the cytoplasm to the cellular membrane, with concurrent increases in Ras binding activity to GST-Raf-1. Overexpression of RasN17, a dominant negative mutant of Ras, attenuates the LDL-induced increases in (1) phosphorylation of ATF-2, (2) phosphorylation of c-Jun, (3) AP-1 binding, and (4) AP-1-driven luciferase activity. To study the effect of p38 in the regulation of an LDL targeting gene, we show that a specific p38 inhibitor attenuates LDL-induced E-selectin at the mRNA level. Thus, LDL activates both p38 and JNK signaling pathways through Ras activation, and furthermore, these events may play an important role in LDL-induced endothelial activation.

Activating Transcription Factor 2↗

PubMed2001

Correlates of work injury frequency and duration among firefighters.

This study examined demographic, personality, and economic incentive correlates of workplace injuries suffered by 171 firefighters over a 12-year period. Results showed that female firefighters experienced more injuries than male firefighters. Several Minnesota Multiphasic Personality Inventory (MMPI) scales (Conversion Hysteria, Psychopathic Deviate, and Social Introversion) were positively related to injury frequency. Regression analyses revealed that age, tenure, gender, marital status, type of injury, and wage variables were significant when predicting the duration of injuries as well as an interaction between marital status and gender. Two MMPI scales (Psychopathic Deviate and Schizophrenia) were also significantly related to injury duration. Indemnity cost estimates were calculated. The results underscore the importance of distinguishing the duration of injury from the occurrence of injury.

Accidents, Occupational↗

PubMed2001

Effect of phosphorus availability on basal root shallowness in common bean.

Root gravitropism may be an important element of plant response to phosphorus availability because it determines root foraging in fertile topsoil horizons, and thereby phosphorus acquisition. In this study we seek to test this hypothesis in both two dimensional paper growth pouch and three-dimensional solid media of sand and soil cultures. Five common bean ( Phaseolus vulgaris L.) genotypes with contrasting adaptation to low phosphorus availability were evaluated in growth pouches over 6 days of growth, and in sand culture and soil culture over 4 weeks of growth. In all three media, phosphorus availability regulated the gravitropic response of basal roots in a genotype-dependent manner. In pouches, sand, and soil, the phosphorus-inefficient genotype DOR 364 had deeper roots with phosphorus stress, whereas the phosphorus-efficient genotype G19833 responded to phosphorus stress by producing shallower roots. Genotypes were most responsive to phosphorus stress in sand culture, where relative root allocation to the 0-3- and 3-6-cm horizons increased 50% with phosphorus stress, and varied 300% (3-6 cm) to 500% (0-3 cm) among genotypes. Our results indicate that (1) phosphorus availability regulates root gravitropic growth in both paper and solid media, (2) responses observed in young seedlings continue throughout vegetative growth, (3) the response of root gravitropism to phosphorus availability varies among genotypes, and (4) genotypic adaptation to low phosphorus availability is correlated with the ability to allocate roots to shallow soil horizons under phosphorus stress.

Biomass↗

PubMed2000

Structure of the FHA1 domain of yeast Rad53 and identification of binding sites for both FHA1 and its target protein Rad9.

Forkhead-associated (FHA) domains have been shown to recognize both pThr and pTyr-peptides. The solution structures of the FHA2 domain of Rad53 from Saccharomyces cerevisiae, and its complex with a pTyr peptide, have been reported recently. We now report the solution structure of the other FHA domain of Rad53, FHA1 (residues 14-164), and identification of binding sites of FHA1 and its target protein Rad9. The FHA1 structure consists of 11 beta-strands, which form two large twisted anti-parallel beta-sheets folding into a beta-sandwich. Three short alpha-helices were also identified. The beta-strands are linked by several loops and turns. These structural features of free FHA1 are similar to those of free FHA2, but there are significant differences in the loops. Screening of a peptide library [XXX(pT)XXX] against FHA1 revealed an absolute requirement for Asp at the +3 position and a preference for Ala at the +2 position. These two criteria are met by a pThr motif (192)TEAD(195) in Rad9. Surface plasmon resonance analysis showed that a pThr peptide containing this motif, (188)SLEV(pT)EADATFVQ(200) from Rad9, binds to FHA1 with a K(d) value of 0.36 microM. Other peptides containing pTXXD sequences also bound to FHA1, but less tightly (K(d)=4-70 microM). These results suggest that Thr192 of Rad9 is the likely phosphorylation site recognized by the FHA1 domain of Rad53. The tight-binding peptide was then used to identify residues of FHA1 involved in the interaction with the pThr peptide. The results are compared with the interactions between the FHA2 domain and a pTyr peptide derived from Rad9 reported previously.

Amino Acid Motifs↗

PubMed2000

II. Structure and specificity of the interaction between the FHA2 domain of Rad53 and phosphotyrosyl peptides.

The forkhead-associated (FHA) domain is a protein module found in many proteins involved in cell signaling in response to DNA damage. It has been suggested to bind to pThr sites of its target protein. Recently we have determined the first structure of an FHA domain, FHA2 from the yeast protein Rad53, and demonstrated that FHA2 binds to a pTyr-containing peptide (826)EDI(pY)YLD(832) from Rad9, with a moderate affinity (K(d) ca. 100 microM). We now report the solution structure of the complex of FHA2 bound with this pTyr peptide. The structure shows that the phosphate group of pTyr interacts directly with three arginine residues (605, 617, and 620), and that the leucine residue at the +2 position from the pTyr interacts with a hydrophobic surface on FHA2. The sequence specificity of FHA2 was determined by screening a combinatorial pTyr library. The results clearly show that FHA2 recognizes specific sequences C-terminal to pTyr with the following consensus: XX(pY)N(1)N(2)N(3), where N(1)=Leu, Met, Phe, or Ile, N(2)=Tyr, Phe, Leu, or Met, and N(3)=Phe, Leu, or Met. Two of the selected peptides, GF(pY)LYFIR and DV(pY)FYMIR, bind FHA2 with K(d) values of 1.1 and 5.0 microM, respectively. The results, along with other recent reports, demonstrate that the FHA domain is a new class of phosphoprotein-binding domain, capable of binding both pTyr and pThr sequences.

Amino Acid Sequence↗

PubMed2000

Potentiation of endogenous fibrinolysis and rescue from lung ischemia/reperfusion injury in interleukin (IL)-10-reconstituted IL-10 null mice.

Little is known about interactions between endogenous anti-inflammatory paradigms and microvascular thrombosis in lung ischemia/reperfusion (I/R) injury. Interleukin (IL)-10 suppresses macrophage activation and down-regulates proinflammatory cytokine production, but there are no available data to suggest a link between IL-10, thrombosis, and fibrinolysis in the setting of I/R. We hypothesized that hypoxia/ischemia triggers IL-10 production, to dampen proinflammatory cytokine and adhesion receptor cascades and to restore vascular patency by fibrinolytic potentiation. Studies were performed in a mouse lung I/R model. IL-10 mRNA levels in lung were increased 43-fold over base line by 1 h of ischemia/2 h of reperfusion, with a corresponding increase in plasma IL-10. Expression was prominently localized in bronchial epithelial cells and mononuclear phagocytes. To study the link between IL-10 and fibrinolysis in vivo, the induction of plasminogen activator inhibitor-1 (PAI-1) was evaluated. Northern analysis demonstrated exaggerated pulmonary PAI-1 expression in IL-10 (-/-) mice after I/R, with a corresponding increase in plasma PAI/tissue-type plasminogen activator activity. In vivo, IL-10 (-/-) mice showed poor postischemic lung function and survival after I/R compared with IL-10 (+/+) mice. Despite a decrease in infiltration of mononuclear phagocytes in I/R lungs of IL-10 (-/-) mice, an increased intravascular pulmonary fibrin deposition was observed by immunohistochemistry and Western blotting, along with increased IL-1 expression. Recombinant IL-10 given to IL-10 (-/-) mice normalized the PAI/tissue-type plasminogen activator ratio, reduced pulmonary vascular fibrin deposition, and rescued mice from lung injury. Since recombinant hirudin (direct thrombin inhibitor) also sufficed to rescue IL-10 (-/-) mice, these data suggest a preeminent role for microvascular thrombosis in I/R lung injury. Ischemia-driven IL-10 expression confers postischemic pulmonary protection by augmenting endogenous fibrinolytic mechanisms.

Animals↗

PubMed2000

Effects of mast cell membrane stabilizing agents in a rat lung ischemia-reperfusion model.

BACKGROUND: The aim of this study was to test the hypothesis that agents which stabilize the mast cell membrane may modulate the phenotype of the vascular wall in a lung ischemia-reperfusion model, including altering expression of endothelial and leukocyte adhesion receptors and the inducible nitric oxide synthase (NOS-2). METHODS: Three sets of rats were given either intravenous saline (group A), ketotifen (group B), or cromolyn (group C), respectively. The left pulmonary artery was ligated temporarily and reopened after 2 hours of ischemia. Then, after a 2-hour period of reperfusion, the left lung was excised. ICAM-1 and NOS-2 were measured at the protein level by Western blotting, and cGMP levels were measured by enzyme-linked immunosorbent assay in the lung tissue specimens for each drug group. RESULTS: ICAM-1 expressions, determined as the intensity of a given band on the Western blot, were 197+/-59 in group B and 195+/-83 in group C versus 369+/-114 in group A (p = 0.002 for analysis of variance). In contrast with ICAM-1, NOS-2 expression was increased by ketotifen or cromolyn treatment (464+/-82 in group B and 507+/-93 in group C, compared with 377+/-44 for group A, p = 0.007). The finding of increased NOS-2 expression in groups B and C is consistent with the observed increase in tissue cGMP levels in the same groups (1.92+/-0.9 pmol/mL for group A versus 7.8+/-3.5 pmol/mL for group B, and 12.4+/-5.8 pmol/mL for group C, p = 0.0004). CONCLUSIONS: These data establish that mast cell stabilizing agents modulate the vascular phenotype in the setting of pulmonary ischemia and reperfusion by decreasing ICAM-1 expression, augmenting expression of NOS-2, and increasing tissue cGMP levels. As decreasing ICAM-1 expression and increasing cGMP levels have proven useful to limit proinflammatory mechanisms of tissue injury, mast cell stabilizing agents may provide a new therapeutic option to improve organ function in the setting of reperfusion.

Analysis of Variance↗

PubMed2000

Tissue responses to natural aragonite (Margaritifera shell) implants in vivo.

The purpose of this study was to access tissue reactions to the outer prismatic (prism) and the inner nacreous (nacre) layers of the fresh water Margaritifera shell. The materials, in granule form, were implanted into the back muscles and femurs of rats for 1, 2, 4, 8 and 16 weeks. In the back muscles, a foreign body reaction was observed around the implants, starting from one week after implantation and reaching maximal proportions at two weeks. After four weeks, a thin layer of fibrous tissue encapsulated the implanted particles. The external surface of the material stained strongly with acid fuchsin, indicating degradation of implant. At femoral sites, newly formed bone was directly applied to the implant surfaces. The outer-most parts of the organic sheets in prisms were not degraded until 16 weeks after implantation and were embedded in the newly formed bone. The interface between bone and the implants showed close fusion by scanning electron microscopy (SEM). Energy dispersive X-ray analysis (EDAX) demonstrated a phosphorous-rich zone in the interface between bone and the implants, and no electron-dense layer in the interface was found by transmission electron microscopy (TEM). We conclude that Margaritifera shells are biocompatible, biodegradable and osteoconductive materials. Bonding between this natural aragonite and bone seems to occur via a phosphorous-rich intermediate layer.

Animals↗

PubMed2000

[A computer-aided analysis system for counting the synaptic numerical density based on disector technique].

The change in the numbers of synapse is of importance in various kinds of physiological and pathological processes. The numerical density is the structural parameter measuring up the numbers of the particles in the space. A new stereological technique, the disector technique, has been described to count the number of particles in a given volume of tissue. It is a technique for counting the number of arbitrary particles in 3-dimensional space using adjacent parallel sections at known distance apart. In this article also discussed is the software for computer assisted count of the synaptic numerical density based on the physical director technique with Visual Basic 4.0.

Algorithms↗

PubMed2000

[Surgery for tumors of the root of neck].

OBJECTIVE: To investigate the clinical value of the surgery for tumors located in the root of the neck. METHODS: A retrospective study was made on 15 cases with tumors in the root of the neck. Seven patients had benign and 8 had malignant tumors. In the malignant group, 4 staged III and 4 staged IV. Patients with benign disease were followed up for more than 3 years, and patients with malignant tumors were followed up from 1 to 5 years (median 2 years). RESULTS: Resection via "L" incision in the root of the neck was employed in 13 cases (7 benign and 6 malignant, clavicle splitting in 1 case) and sternotomy in 2 cases. Only one case in the benign group had complication (chylous leakage). In contrast, 7 complications (2 subclavian vein tearing, 2 brachial plexus injury, 2 chylous leakage and 1 pneumothorax) occurred in 6 patients in the malignant group. The incidence of complication was significantly different between the two groups (P < 0.05). We observed no recurrence in both groups during the period of follow-up. CONCLUSIONS: This study showed that surgery of tumors located in the root of the neck is effective, although the incidence of surgical complication is high for the malignant ones.

Adolescent↗

PubMed1999

Structure and function of a new phosphopeptide-binding domain containing the FHA2 of Rad53.

The forkhead-associated (FHA) domain is a 55-75 amino acid residue module found in >20 proteins from yeast to human. It has been suggested to participate in signal transduction pathways, perhaps via protein-protein interactions involving recognition of phosphopeptides. Neither the structure nor the ligand of FHA is known. Yeast Rad53, a checkpoint protein involved in DNA damage response, contains two FHA domains, FHA1 (residues 66-116) and FHA2 (residues 601-664), the second of which recognizes phosphorylated Rad9. We herein report the solution structure of an "FHA2-containing domain" of Rad53 (residues 573-730). The structure consists of a beta-sandwich containing two antiparallel beta-sheets and a short, C-terminal alpha-helix. Binding experiments suggested that the FHA2-containing domain specifically recognizes pTyr and a pTyr-containing peptide from Rad9, and that the binding site involves residues highly conserved across FHA domains. The results, along with other recent reports, suggest that FHA domains could have pTyr and pSer/Thr dual specificity.

Amino Acid Sequence↗

PubMed1999

Functional characterization of the S. cerevisiae genome by gene deletion and parallel analysis.

The functions of many open reading frames (ORFs) identified in genome-sequencing projects are unknown. New, whole-genome approaches are required to systematically determine their function. A total of 6925 Saccharomyces cerevisiae strains were constructed, by a high-throughput strategy, each with a precise deletion of one of 2026 ORFs (more than one-third of the ORFs in the genome). Of the deleted ORFs, 17 percent were essential for viability in rich medium. The phenotypes of more than 500 deletion strains were assayed in parallel. Of the deletion strains, 40 percent showed quantitative growth defects in either rich or minimal medium.

Culture Media↗

PubMed1999

[A study of HGV infection in liver tissue of hepatocellular carcinoma].

OBJECTIVE: To investigate the prevalence of hepatitis G virus (HGV) in hepatocellular carcinoma (HCC). METHODS: HGV NS5 antigen was detected in paraffin-embedded HCC tissues from 53 autopsy patients by using immunohistochemical method with antiHGV NS5 monoclonal antibody. RESULTS: Among the 53 subsjects, 20(37.7%) had been detected of HGV antigen (HGAg) in HCC tissues. When serological markers were used, the HGAg detection rate was 2/8(25%) in non-B and non-C, 16/41(39%) in HBV and 2/2 in HCV infection groups, respectively. CONCLUSION: The infection of HGV is often seen in patients with HCC. HGV infection does not appear to account for an important independent risk factor for development of HCC.

Adult↗

PubMed1999

Nanocrystalline Silver Particles: Synthesis, Agglomeration, and Sputtering Induced by Electron Beam.

Nanocrystalline silver particles with an average size of 15 nm have been prepared by reducing Ag(NH3)+2 with N2H4. H2O, with sodium dodecylbenzene sulfate (DBS) used as the stabilizing agent. The influence of DBS in the reaction is discussed. When the so-prepared silver particles were observed in situ under a transmission electron microscope, we observed an agglomeration and sputtering phenomenon induced by the electron beam. The possible reason for agglomeration and sputtering is proposed. Silver crystals of hexagonal shape, ranging from 20- to 120-nm in size, were formed on a copper grid. This phenomenon may offer a useful means of forming small particles. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

Influence of titanium ion on mineral formation and properties of osteoid nodules in rat calvaria cultures.

The effect of the addition of titanium ion (Ti) on osteoblast function and the mineralization of osteoid nodules in rat calvaria cultures was characterized. Concentrations of 10 ppm of Ti or more inhibited cell proliferation; 5 ppm or less either had no effect or stimulated proliferation. The number of nodules formed was not influenced by 5 ppm of Ti, but mineral deposition in nodules was suppressed, as revealed by von Kossa staining. Likewise, 5 ppm of Ti inhibited the incorporation of [(45)Ca] in cultures during nodule formation even if the Ti was withdrawn from the medium when mineralization was initiated. In order to test whether the synthesis of osteoid components was affected, the expression of osteonectin (OSN), osteopontin (OPN), osteocalcin (OSC), and alkaline phosphatase (ALP) mRNAs as well as ALP enzyme activity was analyzed. The expression of OSN and OPN mRNAs was reduced dramatically, but OSC mRNA was little affected by 5 ppm of Ti. Ti delayed the development of ALP mRNA expression and enzyme activity relative to the controls. Thus Ti treatment changed the proportional composition of cellular mRNA contributing the osteoblast phenotype.

Alkaline Phosphatase↗

PubMed1999

A failure model for ligaments.

We propose a failure model for ligament which assumes that sequential uncrimping and stretching of collagen fibers is responsible for the mechanical response of ligament. We further assume that the fibers rupture sequentially and in a brittle, strain-limited manner. The model was fit to stress strain curves obtained from medial collateral ligaments of New Zealand White rabbits from two age groups (4 and 7 months). The model indicated that collagen modulus values ranged from 300 to 680 MPa and that fiber failure strains ranged from 6 to 22%. The model provides a convenient means of describing the elastic and failure response of ligament using four structurally based parameters.

Aging↗