Biomedical subjects

T H Han

Publications and source records attributed to T H Han.

At least 19 recordsLinked to original sources

PubMed2002

The neck crease as a landmark of Chassaignac's tubercle in stellate ganglion block: anatomical and radiological evaluation.

BACKGROUND: Stellate ganglion block (SGB) is most commonly performed at the transverse process of the sixth cervical vertebra, the identification of which could be difficult in patients with short and wide necks. This study was conducted to evaluate whether the neck skin crease is a reliable indicator of the C6 level. METHODS: Forty-nine relatively obese pain clinic patients were investigated. They assumed a standard position for SGB. A radiopaque wire was placed along the neck skin crease caudad to the thyroid cartilage. Next, a radiopaque indicator was placed on the skin above the tubercle found to be most prominent by palpation. X-rays of the neck were obtained after each procedure. RESULTS: The probability that the neck crease would cross C5, C6 and C7 was 16%, 71%, and 12%, respectively. The most prominent tubercle corresponded to the C5, C6 and C7 levels in 16%, 69% and l4% of cases, respectively. CONCLUSION: The studied means to identify the C6 transverse process was found to correlate well with each other (P<0.001). Since in 30% of cases the C6 process could not be identified by any of the studied means, radiological guidance is recommended in order to ensure optimal safety and efficacy of SGB in selected cases.

Autonomic Nerve Block↗

PubMed2001

Modulation of nitric oxide bioavailability by erythrocytes.

Nitric oxide (NO) activates soluble guanylyl cyclase in smooth muscle cells to induce vasodilation in the vasculature. However, as hemoglobin (Hb) is an effective scavenger of NO and is present in high concentrations inside the red blood cell (RBC), the bioavailability of NO would be too low to elicit soluble guanylyl cyclase activation in the presence of blood. Therefore, NO bioactivity must be preserved. Here we present evidence suggesting that the RBC participates in the preservation of NO bioactivity by reducing NO influx. The NO uptake by RBCs was increased and decreased by altering the degree of band 3 binding to the cytoskeleton. Methemoglobin and denatured hemoglobin binding to the RBC membrane or cytoskeleton also were shown to contribute to reducing the NO uptake rate of the RBC. These alterations in NO uptake by the RBC, hence the NO bioavailability, were determined to correlate with the vasodilation of isolated blood vessels. Our observations suggest that RBC membrane and cytoskeleton associated NO-inert proteins provide a barrier for NO diffusion and thus account for the reduction in the NO uptake rate of RBCs.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed2001

14-3-3tau associates with and activates the MEF2D transcription factor during muscle cell differentiation.

Myocyte enhancer binding factor 2 (MEF2) proteins belong to the MADS box family of transcription factors and four MEF2 proteins, MEF2A, MEF2B, MEF2C and MEF2D, have been found. MEF2 proteins have been shown to play critical roles in differentiation of muscles and neuronal tissues. How transactivational activity of MEF2 proteins is regulated is not fully understood. MEF2 proteins are activated by several kinases, including Erk5 and calcium/calmodulin-dependent kinase, and interact with repressors, including histone deacetylases 4 and 5 (HDAC4 and HDAC5) and Cabin1. During the effort to understand regulation of MEF2 activity, we identified 14-3-3tau as a MEF2D-interacting molecule by yeast two-hybrid screening. We found that 14-3-3tau forms a complex with MEF2D in vivo and specifically enhances MEF2 transactivational activity. The results from transient transfection and co-precipitation experiments suggest that 14-3-3tau activates MEF2D by competitively inhibiting HDAC4 from binding to MEF2D and thereby affects muscle cell differentiation.

14-3-3 Proteins↗

PubMed2001

The laryngeal mask airway is effective (and probably safe) in selected healthy parturients for elective Cesarean section: a prospective study of 1067 cases.

PURPOSE: To report on the use of the laryngeal mask airway (LMA) for elective Cesarean section in 1067 consecutive ASA I-II patients preferring general anesthesia. METHODS: Patients were excluded if they had pharyngeal reflux, a pre-pregnancy body mass index >30, or had a known/predicted difficult airway. Patients were fasted for six hours and given ranitidine/sodium citrate. A rapid sequence induction was performed with thiopentone and suxamethonium. The LMA was inserted by experienced users. Anesthesia was maintained with N(2)O and 50% O(2) and a volatile agent. Cricoid pressure was maintained until delivery, but was relaxed if insertion/ventilation was difficult. Patients were intubated if an effective airway was not obtained within 90 sec, or SpO(2) <94%, or end-tidal CO(2) >45 mmHg. Postdelivery, vecuronium and fentanyl were administered. RESULTS: An effective airway was obtained in 1060 (99%) patients, 1051 (98%) at the first attempt and nine (1%) at the second or third attempt. Air leakage or partial airway obstruction occurred in 22 (21%) patients, and seven (0.7%) patients required intubation. There were no episodes of hypoxia (SpO(2) <90%), aspiration, regurgitation, laryngospasm, bronchospasm or gastric insufflation. Surgical conditions were satisfactory and all APGAR scores were >/=7 after five minutes. CONCLUSION: We conclude that the LMA is effective and probably safe for elective Cesarean section in healthy, selected patients when managed by experienced LMA users.

Adolescent↗

PubMed2000

Neutralization epitopes on the antigenic domain II of the Orientia tsutsugamushi 56-kDa protein revealed by monoclonal antibodies.

Monoclonal antibodies (MoAbs) reactive with the authentic Orientia tsutsugamushi 56-kDa protein were generated. MoAb FS10 and FS15 showed in vitro, as well as, in vivo neutralizing activity upon O. tsutsugamushi infection. Deletion mutants of the gene for 56-kDa protein of O. tsutsugamushi Boryong were expressed to map the binding region. FS10 and FS15 are bound to amino acids (aa) located in an antigenic domain II, at residues 140-160 and 187-214, respectively. Computer modeling indicated that aa 146-153 were important for antigenicity against FS10. A sequence for aa 142-150 was highly homologous between oriential strains. These results suggest that the antigenic determinant for neutralizing MoAbs is an epitope within aa 140-160. Furthermore, this region may be important for the adhesion/invasion or intracellular survival of O. tsutsugamushi within host cells.

Amino Acid Sequence↗

PubMed2000

Sp1 mediates constitutive and transforming growth factor beta-inducible expression of urokinase type plasminogen activator receptor gene in human monocyte-like U937 cells.

Urokinase type plasminogen activator receptor (uPAR) is known to be involved in conversion of plasminogen into plasmin and its expression can be regulated by a variety of biological agents including transforming growth factor beta (TGF-beta). In the present study, we cloned the promoter region of the human uPAR (huPAR) gene (-653 to +61) and investigated the transcription regulatory mechanism of the expression of the huPAR gene upon treatment with TGF-beta in human monocyte-like U937 cells. By deletion and point mutational analysis of the huPAR gene promoter, it was found that the sequence positioned at -70 is required for both constitutive and TGF-beta-inducible expression of the huPAR gene in U937 cells. Using electrophoretic mobility shift assay, we could observe that Sp1 formed a DNA-protein complex at the -70 sequence. In addition, antisense oligonucleotide against human Sp1 blocked both constitutive and TGF-beta-inducible expression of the luciferase reporter gene driven by the huPAR gene promoter in U937 cells. These results led us to conclude that Sp1 transcription factor mediates constitutive and TGF-beta-inducible expression of the huPAR gene in U937 cells through binding to the sequence located at -70.

Electrophoresis↗

PubMed2000

Cellular invasion of Orientia tsutsugamushi requires initial interaction with cell surface heparan sulfate.

Role of transmembrane heparan sulfate proteoglycans on invasion of Orientia tsutsugamushi into host cells was investigated. Pretreatment with heparan sulfate and heparin inhibited the infection of O. tsutsugamushi for L cell, mouse fibroblast, whereas other glycosaminoglycans had little effect. These same treatments were also shown to reduce the infection in a dose-dependent manner, and enzymatic treatment of cells with heparitinase, but not chondroitinase ABC, inhibited the infection. In addition, mutant cell lines of Chinese hamster ovarian cell defective in heparan sulfate synthesis but not chondrotin sulfate synthesis and defective in all glycosaminoglycan synthesis showed marked reduction in susceptibility to infection by O. tsutsugamushi. Also mutant cell lines, which express heparan sulfate proteoglycans at low level, showed intermediate level of infectivity. Finally O. tsutsugamushi bind to(35)S-labelled heparin. Collectively, these findings provide strong evidence that heparan sulfate proteoglycans contribute to the attachment of O. tsutsugamushi to the cells.

Animals↗

PubMed2000

Genetic diversity of Chilean and Brazilian alstroemeria species assessed by AFLP analysis.

One to three accessions of 22 Alstroemeria species, an interspecific hybrid (A. aurea x A. inodora), and single accessions of Bomarea salsilla and Leontochir ovallei were evaluated using the AFLP-marker technique to estimate the genetic diversity within the genus Alstroemeria. Three primer combinations generated 716 markers and discriminated all Alstroemeria species. The dendrogram inferred from the AFLP fingerprints supported the conjecture of the generic separation of the Chilean and Brazilian Alstroemeria species. The principal co-ordinate plot showed the separate allocation of the A. ligtu group and the allocation of A. aurea, which has a wide range of geographical distribution and genetic variation, in the middle of other Alstroemeria species. The genetic distances, based on AFLP markers, determined the genomic contribution of the parents to the interspecific hybrid.

Brazil↗

PubMed2000

Prevention of postoperative nausea and vomiting by continuous infusion of subhypnotic propofol in female patients receiving intravenous patient-controlled analgesia.

In this prospective, randomized, double-blind, placebo-controlled study, the use of continuous subhypnotic propofol infusion as an antiemetic in fentanyl intravenous patient-controlled analgesia (i.v. PCA) was investigated during the first 24 h after surgery. One hundred female patients, ASA I-II, aged 20-71 yr, undergoing major gynaecological or orthopaedic surgery, were included. Either propofol 10 mg or placebo (1 ml of Intralipid) was given and one of the following five regimens was maintained for 24 h: propofol 5, 10, 15 or 20 microg kg(-1) min(-1) or Intralipid 1 ml h(-1) as a placebo. Fentanyl i.v. PCA was started in the postanaesthesia care unit for postoperative analgesia. Significantly more of the patients given propofol 15 and 20 microg kg(-1) min(-1) experienced no nausea or vomiting compared with those given placebo (65% and 70% versus 25%; P<0.05). Patients given propofol 20 microg kg(-1) min(-1) reported more sedation than those in the other groups 4 h after surgery (P<0.05).

Adult↗

PubMed2000

Expression of chemokine genes in murine macrophages infected with Orientia tsutsugamushi.

Scrub typhus, caused by Orientia tsutsugamushi infection, is characterized by local as well as systemic inflammatory manifestations. Inflammation is initiated by O. tsutsugamushi-infected macrophages and endothelial cells in the dermis. We investigated the regulation of chemokine induction in macrophage cell line J774A.1 in response to O. tsutsugamushi infection. The mRNAs for macrophage inflammatory proteins 1alpha/beta (MIP-1alpha/beta), MIP-2, and macrophage chemoattractant protein 1 were induced within 30 min, and their levels showed a transitory peak for 3 to 12 h. However, the lymphotactin, eotaxin, gamma interferon-inducible protein 10, and T-cell activation gene 3 mRNAs were not detected by RNase protection assays. Heat-killed O. tsutsugamushi induced a similar extent of chemokine responses. Induction of the chemokine genes was not blocked by the eukaryotic protein synthesis inhibitor cycloheximide, suggesting that de novo synthesis of host cell protein is not required for these transcriptional responses. The induction of chemokine mRNAs by O. tsutsugamushi was blocked by the inhibitors of NF-kappaB activation. Furthermore, O. tsutsugamushi induced the nuclear translocation and activation of NF-kappaB. These results demonstrate that heat-stable molecules of O. tsutsugamushi induce a subset of chemokine genes and that induction involves activation of the transcription factor NF-kappaB.

Animals↗

PubMed1999

CD28-mediated regulation of the c-jun promoter involves the MEF2 transcription factor in Jurkat T cells.

Within a few minutes of T-cell activation, transcription of a set of genes including c-fos and c-jun is activated. For maximal induction of c-jun, at least two major signal pathways are required. One can be triggered by T-cell receptor engagement or phorbol esters and the other by anti-CD28 engagement. The c-jun promoter region between -117 and -50 contains binding sites for the transcription factors Spl, CTF, ATF/CREB, and MEF2. In this study, we sought to map the sequences in the c-jun promoter responsible for CD28-mediated induction in activated Jurkat T cell by point mutational analysis. We found that mutation of the c-jun MEF2 site strongly reduces CD28 induction of the promoter in Jurkat T cells and that MEF2D is the major binding molecule to the c-jun MEF2 site in Jurkat T cells. Mutation of the c-jun ATF site also partially reduced CD28 induction of the promoter. In addition, pretreatment with an endolysomotropic agent NH4Cl, an acidic sphingomyelinase inhibitor, completely inhibited the activation of the c-jun promoter by anti-CD28 antibody treatment, whereas pretreatment with wortmannin, a PI3-kinase inhibitor, did not affect the induction of the c-jun promoter. These results suggest that CD28 signaling leading to the c-jun promoter involves acidic sphingomyelinase, but not PI3-kinase, to activate factors binding to the MEF2 and ATF sites.

Binding Sites↗

PubMed1999

Requirement of MEF2D in the induced differentiation of HL60 promyeloid cells.

The regulatory role of MEF2 (myocyte enhancer binding factor 2) proteins in nonmuscle tissues has not been well characterized. We examined the expression of MEF2 family members, namely, MEF2A, -B, -C, and -D, in the differentiation of HL60 promyeloid cells and observed the remarkable increase in the expressions of MEF2A and MEF2D proteins during the differentiation process into monocytes. To examine the role of MEF2, we expressed a dominant-negative form of MEF2D, without its transactivation domain, in HL60 cells. When the HL60 cell line expressing the mutant MEF2D was induced to differentiate by VitD(3) treatment, cell surface expression of CD14 and the ability to reduce NBT, which are important characteristics of differentiated monocytes, were significantly decreased compared with control HL60 cells. These results show that MEF2D is required in the differentiation process along the monocyte/macrophage lineage,

Base Sequence↗

PubMed1997

Induction of neutralizing antibody in mice by immunization with recombinant 56 kDa protein of Orientia tsutsugamushi.

Anti-oriential antibody inhibits Orientia tsutsugamushi attachment to, and penetration of, host cells. However, O. tsutsugamushi antigens that induce the production of a neutralizing antibody have not been identified. The authors immunized mice and rabbits with the recombinant 56 kDa protein of O. tsutsugamushi fused to the maltose binding protein of Escherichia coli (MBP-Bor56) and analysed their effect on O. tsutsugamushi attachment to or penetration of L929 cells. O. tsutsugamushi attachment and penetration were measured by using an indirect immunofluorescent antibody assay (IFA). O. tsutsugamushi growth in L929 cells was determined by [3H]thymidine uptake assay. By IFA, we observed a 96% reduction of attachment or penetration of O. tsutsugamushi treated with rabbit anti-MBP-Bor56 sera. [3H]thymidine uptake showed that mouse anti-MBP-Bor56 sera caused a 91% reduction in O. tsutsugamushi growth, when compared to mouse anti-MBP sera. These results suggest that the 56 kDa protein of O. tsutsugamushi plays an important role in O. tsutsugamushi attachment to or penetration of cells.

ATP-Binding Cassette Transporters↗

PubMed1997

Isolation of a new Orientia tsutsugamushi serotype.

Orientia tsutsugamushi, the etiological agent of scrub typhus, is an antigenically diverse organism and many serologically distinct strains have been identified. The 56 kDa protein of O. tsutsugamushi, a major protein in the outer membrane, has been thought to be responsible for this antigenic variability. A strain of O. tsutsugamushi isolated in Korea cross-reacted with both Gilliam strain-specific and Karp strain-specific monoclonal antibodies. When its 56 kDa protein gene was cloned and analyzed, its sequence showed variation especially between 1,200 and 1,250 bp, showing that this isolate is a new O. tsutsugamushi strain.

Amino Acid Sequence↗

PubMed1997

Mapping of antigenic determinant regions of the Bor56 protein of Orientia tsutsugamushi.

The 56-kDa protein (Bor56) of Orientia tsutsugamushi is an immunoprotective antigen and is the target molecule of neutralizing antibodies. This antigen is recognized by almost all of the serum antibodies produced by patients in the convalescence phase of scrub typhus. We expressed the Bor56 open reading frame in Escherichia coli and generated from it a series of deletion constructs as MalE fusion proteins. Antibody-binding domains were characterized by using patient sera, mouse monoclonal antibodies (MAbs), and Bor56-immunized-mouse sera. None of the antibodies bound to a fusion protein containing the carboxy-terminal 140 amino acids (aa) of the Bor56 protein, suggesting that the carboxy-terminal domain of Bor56 is not exposed on the surface of the molecule. Human immunoglobulin M (IgM) antibodies predominantly bound to antigenic domain I (AD I; amino acids [aa] 19 to 113) and AD III (aa 243 to 328). Human IgG antibodies also showed preferential binding to AD I. The epitope recognized by strain-specific MAb (KI4) or group-specific MAb (KI57) was mapped to AD II (aa 142 to 203). Mouse serum antibodies, elicited by immunization with deletion mutants, consistently bound to AD III. Moreover, the carboxy-terminal 140 aa of the Bor56 protein did not elicit an antibody response in C3H/HeDub mice. A model of the antigenic structure of Bor56 is presented and discussed. These results suggest that antigenic fragments from AD I and AD III are useful in the induction of humoral immunity against O. tsutsugamushi. These antigenic analyses provide an important foundation for further analyses of the neutralizing-antibody responses generated during rickettsial infections. They also provide potential peptide substrates for diagnostic assays and vaccine strategies.

Animals↗

PubMed1995

Regulatory role of MEF2D in serum induction of the c-jun promoter.

Serum induction of c-jun expression in HeLa cells requires a MEF2 site at -59 in the c-jun promoter. MEF2 sites, found in many muscle-specific enhancers, are bound by a family of transcription factors, MEF2A through -D, which are related to serum response factor in their DNA binding domains. We have found that MEF2D is the predominant protein in HeLa cells that binds to the c-jun MEF2 site. Serum induction of a MEF2 reporter gene was not observed in a line of NIH 3T3 cells which contain low MEF2 site binding activity. Transfection of MEF2D into NIH 3T3 cells reconstituted serum induction, demonstrating that MEF2D is required for the serum response. Deletion analysis of MEF2D showed that its DNA binding domain, when fused to a heterologous transcriptional activation domain, was sufficient for serum induction of a MEF2 reporter gene. This is the domain homologous to that in the serum response factor which is required for serum induction of the c-fos serum response element, suggesting that serum regulation of c-fos and c-jun may share a common mechanism.

3T3 Cells↗

PubMed1994

A fluorescent in situ hybridization analysis of the chromosome constitution of ejaculated sperm in a 47,XYY male.

Two semen samples from a 47,XXY male were examined using chromosome-specific DNA probes and fluorescent in situ hybridization (FISH) to determine the distribution of sex chromosomes and an autosome (chromosome 17) in the sperm. A motile population of sperm was also prepared from one sample using the swim-up technique to compare the motile and total sperm populations. Chromosomes were localized using single FISH and a biotinylated chromosome 17 probe (TR17), or double FISH using a biotinylated X chromosome probe (TRX) and a digoxigenin-labelled Y chromosome probe (HRY). Labelling efficiencies were 95-98%. Ploidy levels were estimated by measurement against a microscope eye-piece graticule. The overall ratio of X- to Y-bearing sperm was 47% to 48.4% in the neat samples, and 48.4% to 45.3% in the swim-up fraction. Neither of the ratios was significantly different from 1:1. The frequencies of monosomic and disomic (but otherwise haploid sperm) were not different from the frequencies we observed in normal donors. In contrast, the frequencies of both diploid and tetraploid cells were increased in the neat samples of the XYY male. In the swim-up fractions, however, none of these parameters differed from those of ten normal semen donors. These results support the hypothesis that the extra Y chromosome in XYY men is eliminated during spermatogenesis.

Adult↗

PubMed1992

Mapping of epidermal growth factor-, serum-, and phorbol ester-responsive sequence elements in the c-jun promoter.

Expression of the nuclear proto-oncogene c-jun is rapidly and transiently induced by many growth factors, serum, and tumor promoters. The sequence elements in the c-jun promoter involved in serum or growth factor induction have not been identified. The c-jun promoter region between -117 and -72 contains binding sites for the transcription factors Sp1, CTF, and AP-1. An additional sequence element has been noted at position -59. This A+T-rich sequence, formerly proposed as a TFIID-binding site, conforms to the consensus binding sequence of a recently identified factor, RSRF (related to serum response factor). In this study, we mapped the sequences in the c-jun promoter responsible for epidermal growth factor (EGF), serum, and 12-O-tetradecanoylphorbol-13-acetate (TPA) induction by deletion and point mutational analysis. We found that the c-jun RSRF site is an important element for EGF and serum induction of the promoter and that there are several factors in HeLa nuclear extracts which specifically bind to this site. The RSRF site was also sufficient for EGF, serum, and TPA induction when assayed on a heterologous promoter. The c-jun AP-1 site was not required for EGF, serum, or TPA induction but was sufficient to mediate a weak response to these agents when assayed on a heterologous promoter. Double mutation of the RSRF and AP-1 sites suggests that there is an additional TPA-responsive element between -80 and +150 in the c-jun promoter.

Base Sequence↗