Biomedical subjects

J Lu

Publications and source records attributed to J Lu.

At least 397 records · Page 22Linked to original sources

PubMed1998

Effects of isovolumetric hemodilution treatment and superoxide dismutase on ischemic reperfused hearts in rabbit.

UNLABELLED: The isovolumetric hemodilution treatment reduces ischemic injury and anti-radical interventions may reduce reperfusion injury. However, the effects of the treatment with both interventions have never been investigated. In the present study, anesthetized rabbits underwent 45 min of coronary artery ligation, which was followed by 180 min of reperfusion. Ten animals in each group received: (i) normal saline only; (ii) isovolumetric hemodilution with Dextran 40 during ischemia; (iii) superoxide dismutase (SOD) 1 min before and during reperfusion; and (iv) combined treatment with hemodilution and SOD. RESULTS: (1) compared with those of the control group, left ventricular peak pressure (LVP) and +/- dp/dt-max improved significantly in the animals which received hemodilution or SOD alone, and left ventricular systolic function of the animals with the combination therapy improved further; (2) infarct size averaged 54.4 +/- 2.6% of the risk region in controls and was significantly smaller in the rabbits that were treated with hemodilution (32.8 +/- 1.8%) (p < 0.05), with SOD (42.1 +/- 3.2%) (p < 0.05) and with the combination therapy (23.4 +/- 1.5%) (p < 0.01). Therefore, (1) in groups where either hemodilution during ischemia or removal of oxygen radicals during reperfusion was done left ventricular systolic function and salvaged ischemic reperfused myocardium improved significantly; (2) in this acute model, SOD improved left ventricular systolic and diastolic functions and reduced infarct size further when given to the animals that had been treated with hemodilution.

Animals↗

PubMed1998

Translaminar facet screw placement: an anatomic study.

Anatomic measurements for screw path length, caudal and lateral angles, and superior and inferior lamina border thicknesses from L1 to L5 were measured for translaminar facet screw fixation in 30 dried lumbar spines. All measured values were fairly constant from L1 to L5. The mean values of the length of the screw path and lateral angle gradually increased from L1-2 to L5-S1 levels (41 to 54 mm, 39 degrees to 60 degrees, respectively). The caudal angle of screw placement relative to transverse plane gradually decreased from L1-2 to L5-S1 levels (60 degrees to 38 degrees). The superior border of the lamina was relatively thinner, with the mean thickness ranging from a minimum of 1.3 mm at L1 to a maximum of 2.0 mm at L5. The thickness of the inferior border of the lamina increased from L1 to L5 (from 6.7 mm to 7.8 mm). This study confirmed that a translaminar facet screw, 40 mm to 50 mm long at L1 to L5 levels, 60 mm long at L5-S1 level, and 4.5 mm in diameter, should be inserted through the lumbar facet joint at an angle of 40 degrees to 50 degrees laterally at L1 to L5 levels, 50 degrees to 55 degrees laterally at L5-S1 level, 45 degrees to 60 degrees caudally at L1 to L5 levels, and 35 degrees to 40 degrees at L5-S1 level caudally.

Adult↗

PubMed1998

Epithelial ion transport and barrier abnormalities evoked by superantigen-activated immune cells are inhibited by interleukin-10 but not interleukin-4.

Many studies have indicated an association between bacteria and the severity of enteric secretory or inflammatory disorders. We previously showed that monolayers of human T84 epithelial cells display altered ion transport and permeability after coculture with Staphylococcus aureus enterotoxin B (SEB, a model superantigen)-activated immune cells, where interferon-gamma and tumor necrosis factor-alpha were key mediators in the pathophysiology. Here we examined whether the regulatory Th2-type cytokines, interleukin (IL)-10 and IL-4, could prevent these epithelial irregularities. T84 monolayers were cocultured with human peripheral blood mononuclear cells (PBMC) or T cell-enriched, monocyte-depleted PBMC (T + B cells) +/- SEB for 20 hr in the presence or absence of IL-10 or IL-4. Subsequently, T84 monolayers were mounted in Ussing chambers and ion transport (short-circuit current (Isc) and DeltaIsc evoked by forskolin) and permeability (ion resistance and probe fluxes) were assessed. IL-10 dose-dependently inhibited the increased T84 permeability and the reduced responsiveness to forskolin that were evoked by coculture with SEB-activated PBMC or T + B cells. Similar changes in T84 function occurred in response to conditioned medium from SEB-activated immune cells; however, addition of IL-10 to the conditioned medium did not prevent the changes in epithelial function. In contrast, when PBMC were stimulated with SEB in the presence of IL-10, the subsequent conditioned medium was less effective in evoking altered epithelial function. These data suggest that the affect of IL-10 was due to effects on the immune cells and not directly on the epithelium. In contrast to IL-10, IL-4 did not ameliorate any of the immune-mediated changes in T84 function. We conclude that IL-10 can reduce the epithelial functional changes caused by SEB-activated immune cells and this data adds further support for IL-10 immunotherapy in the treatment of intestinal secretory or inflammatory disorders.

Cell Line↗

PubMed1997

Specific interaction of the PDZ domain protein PICK1 with the COOH terminus of protein kinase C-alpha.

PICK1 is a protein kinase C (PKC) alpha-binding protein initially identified using the yeast two-hybrid system. Here we report that PICK1 contains a PDZ domain that interacts specifically with a previously unidentified PDZ-binding domain (QSAV) at the extreme COOH terminus of PKCalpha and that mutation of a putative carboxylate-binding loop within the PICK1 PDZ domain abolishes this interaction. The PDZ-binding domain in PKCalpha is absent from other PKC isoforms that do not interact with PICK1. We also demonstrate that PICK1 can homooligomerize through sequences that are distinct from the carboxylate-binding loop, suggesting that self-association and PKCalpha binding are not mutually exclusive. A Caenorhabditis elegans PICK1-like protein is also able to bind to PKCalpha, suggesting a conservation of function through evolution. Association of PKCalpha with PICK1 provides a potential mechanism for the selective targeting of PKCalpha to unique subcellular sites.

Amino Acid Sequence↗

PubMed1997

Vulnerability of the recurrent laryngeal nerve in the anterior approach to the lower cervical spine.

STUDY DESIGN: To perform anatomic dissections and measurements of the recurrent laryngeal nerve between the inferior thyroid artery and superior border of the clavicle (mid-portion) on both sides. OBJECTIVES: To determine quantitatively the differences in course and location between the recurrent laryngeal nerves on both sides and to relate this to the vulnerability of the recurrent laryngeal nerve during an anterior approach to the lower cervical spine. SUMMARY OF BACKGROUND DATA: The midportion of the recurrent laryngeal nerve is usually encountered in the anterior approach to the lower cervical spine, especially on the right side. No quantitative regional anatomy describing the course and location of the mid-portion of the recurrent laryngeal nerve is available in the literature. METHODS: Fifteen adult cadavers were used for dissections of the recurrent laryngeal nerve. The length of the recurrent laryngeal nerve between the superior border of the clavicle and the inferior thyroid artery, and the angle of the recurrent laryngeal nerve with respect to sagittal plane, were measured bilaterally. In addition, six cross-sections at C7 were obtained to determine the linear distances between esophagotracheal groove and the recurrent laryngeal nerve. RESULTS: The recurrent laryngeal nerve on the right runs in a superior and medial direction, with an angle of 25.0 degrees +/- 4.7 degrees relative to sagittal plane, compared with 4.7 degrees +/- 3.7 degrees on the left. The length of the recurrent laryngeal nerve between the superior border of the clavicle and the inferior thyroid artery is 23.0 +/- 4.4 mm on the left, and 22.8 +/- 4.3 mm on the right. The recurrent laryngeal nerve lies deep within the esophagotracheal groove on the left, but 6.5 +/- 1.2 mm anterior and 7.3 +/- 0.8 mm lateral to the esophagotracheal groove on the right. CONCLUSIONS: The recurrent laryngeal nerve on the right side is highly vulnerable to injury if ligature of the inferior thyroid vessels is not performed as laterally as possible or if retraction of the midline structures along with the recurrent laryngeal nerve is not performed intermittently. Avoiding injury to the recurrent laryngeal nerve, especially on the right side, is a major consideration during an anterior approach to lower cervical spine.

Aged↗

PubMed1997

Determination of capsaicin and zucapsaicin in human serum by high-performance liquid chromatography with fluorescence detection.

A reversed-phase high-performance liquid chromatographic (HPLC) assay was developed to analyze capsaicin and zucapsaicin (civamide) in human serum at concentrations from 1 to 100 ng/ml. Human serum specimens were extracted twice with hexane-methyl tert.-butyl ether (1:1). The chromatographic separation was carried out on a C18 column at 40 degrees C using a mobile phase consisting of 40% acetonitrile in water with 5% tetrahydrofuran and 1% acetic acid. The concentration of the eluting compounds was monitored by a fluorescence detector with excitation at 270 nm and an emission cutoff of 300 nm. No interferences were observed from the extract of blank serum. The standard curves were linear in the detection range. The relative standard deviation of the assay was better than 8.4%. The limit of detection was 0.5 ng/ml.

Analgesics, Non-Narcotic↗

PubMed1997

Regulation of C-C chemokine production by murine T cells by CD28/B7 costimulation.

C-C chemokines play an important role in recruitment of T lymphocytes to inflammatory sites. T lymphocytes secrete chemokines, but the activation requirements for chemokine production by T cells are uncertain. We studied the regulation of C-C chemokine production by CD28 costimulatory signals by murine T lymphocytes. Splenocytes from BALB/c mice cultured with anti-CD3 mAb expressed macrophage-inflammatory protein (MIP)-1alpha mRNA and secreted MIP-1alpha, which was inhibited by anti-B7-1 plus anti-B7-2 mAbs. MIP-1alpha production by Ag-stimulated T cells from DO.11.10 TCR transgenic mice was augmented by anti-CD28 mAb and increased compared with DO.11.10/CD28(-/-) cells. When T cell costimulation was provided by IL-2, MIP-1alpha was not enhanced. Studies with IL-2, IL-4, STAT4, and STAT6 knock-out mice suggested that chemokine production is controlled by pathways different from those regulating T cell differentiation. Thus, CD28 costimulation may amplify an immune response by stimulating T cell survival, proliferation, and production of chemokines that recruit T cells to inflammatory sites.

Animals↗

PubMed1997

Identification of positively charged residues contributing to the stability of plasminogen activator inhibitor 1.

Plasminogen activator inhibitor 1 (PAI-1), a member of the serpins, has a unique conformational flexibility. A typical characteristic is its intrinsic lability resulting in the conversion of the active conformation to a latent conformation. In the present study, we have evaluated the effect of substitution of positively charged residues located at the turn connecting strand s4C with strand s3C, either with negatively charged or with neutral residues, on the functional stability of PAI-1. The following mutants were constructed, purified and characterized in comparison to wild-type (wt) PAI-1: PAI-1-R186E,R187E (Arg186--> Glu and Arg187--> Glu), PAI-1-H190E,K191E (His190--> Glu and Lys191--> Glu) and PAI-1-H190L,K191L (His190--> Leu and Lys191--> Leu). In contrast to wtPAI-1 the mutants exhibited no inhibitory activity. Whereas latent wtPAI-1 can be reactivated (up to a specific activity of 78+/-19%) by treatment with guanidinium chloride, a similar treatment applied to these mutants resulted in a significant but relatively small increase of specific activity (i.e. to 14%). Evaluation of the functional stability (at 37 degrees C, pH 5.5, 1 M NaCl revealed a strongly decreased functional stability compared to wtPAI-1 (i.e. 3-9 h for the mutants vs. > 24 h for wtPAI-1). Further characterization by heat denaturation studies and plasmin susceptibility confirmed that removal or reversal of the positive charge on the turn connecting s4C with s3C results in PAI-1 mutants with a highly accelerated conversion of active to latent forms. We can therefore conclude that the pronounced positive charge in the turn connecting s4C with s3C is of the highest importance for the functional stability of PAI-1.

Electrophoresis, Polyacrylamide Gel↗

PubMed1997

Nucleotide sequences and gene organization of TaqI endonuclease isoschizomers from Thermus sp. SM32 and Thermus filiformis Tok6A1.

Eight TaqI isoschizomer genes, two from Yellowstone National Park, one from Japan, two from New Zealand, two from Portugal, and one from the Azores (1000 miles west of Portugal), were PCR-amplified and sequenced. Sequence alignment of isoschizomers isolated from close geographical locations shows identical or almost identical protein sequences, while isoschizomers from distant sites demonstrate considerable diversity, ranging from 54 to 75% in amino acid identity. Accordingly, these isoschizomers were arranged into four geographical groups, i.e., USA as represented by Thermus aquaticus YT1, Japan by Thermus thermophilus HB8, New Zealand by Thermus filiformis Tok6A1, Portugal by Thermus sp. SM32. The complete ORFs of two new representative genes, tfiTok6A1I and tsp32IR, were obtained by bubble PCR. Unlike M . TaqI-R.TaqI and M . TthHB8I-R . TthHB8I which exhibit an unusual 13-codon overlap, the methylase and endonuclease genes are each separated by 15 nucleotides in the TfiTok6A1I and Tsp32IR restriction-modification systems. Phylogenetic analysis suggests that initially TfiTok6A1I diverged from a common ancestor, then Tsp32IR branched out, and finally TaqI and TthHB8I diverged from each other during evolution.

Amino Acid Sequence↗

PubMed1997

Isolation and characterization of chicken beta-catenin.

beta-catenin interacts with a number of proteins in different important biological processes, including cell adhesion through cadherins, actin organization through fascin, body axis determination through Wnt signaling, tumor suppression through APC, and transcriptional activation through LEF-1. To examine its function in chicken embryogenesis, we isolated the chicken homolog of beta-catenin from a chicken embryo cDNA library. The sequence is highly conserved at the amino acid level between chicken, mouse (99%), human (99%) and Xenopus (97%). In-situ hybridization and immunostaining showed that in the developing limb, it is specifically expressed in the apical ectodermal ridge, suggesting a role in epithelial-mesenchymal interactions.

Amino Acid Sequence↗

PubMed1997

Tertiary structure of RBD2 and backbone dynamics of RBD1 and RBD2 of the human U1A protein determined by NMR spectroscopy.

The human U1A protein has two putative RNA binding domains, one at the N-terminal region of the protein (RBD1) and the other at the C-terminal end (RBD2). RBD1 binds tightly and specifically to one of the stem loops of the U1 snRNA, as well as to its own 3'-UTR. In contrast, RBD2 does not appear to associate with any RNA. The two domains share 25% amino acid identity, and both have the same betaalphabeta-betaalphabeta secondary structure fold. In this work, 13C/15N/1H multidimensional NMR methods were used to obtain side-chain assignments for RBD2, and then the tertiary structure was calculated using a distance geometry/simulated annealing algorithm that employs pairwise Gaussian metrization. RBD2 is shown to fold into an alpha/beta sandwich with a four-stranded antiparallel beta-sheet, which is the typical global topology of these domains. Specific structural features of RBD2 include a beta-bulge in beta2, N-capping boxes for both alpha-helices, and an extremely shallow twist of its beta-sheet. The 15N backbone dynamics of these two structurally homologous RBDs are significantly different, compared using order parameters and T2 exchange terms in the Lipari and Szabo model-free formalism. Conformational exchange observed in RBD1, which is absent in RBD2, may correlate to the mechanism of RNA binding.

Amino Acid Sequence↗

PubMed1997

Determination of paromomycin in human plasma and urine by reversed-phase high-performance liquid chromatography using 2,4-dinitrofluorobenzene derivatization.

A sensitive high-performance liquid chromatographic method for the determination of paromomycin in human plasma and urine was developed. Paromomycin was quantitated following pre-column derivatization with 2,4-dinitrofluorobenzene (DNFB). The chromatographic separation was carried out on a C18 column at 50 degrees C using a mobile phase consisting of 64% methanol in water adjusted to pH 3.0 with phosphoric acid. The eluents were monitored by UV detection at 350 nm. The linearity of response for paromomycin was demonstrated at concentrations from 0.5 to 50 microg/ml in plasma and 1 to 50 microg/ml in urine. The relative standard deviation of the assay procedure is less than 5%.

Anti-Bacterial Agents↗

PubMed1997

Purification and binding properties of a human ficolin-like protein.

Ficolin was initially identified from porcine uterus as a TGF-beta 1 binding protein and is considered to have an overall structure similar to that of the complement protein C1q and the collectins. Recent studies have shown that human ficolin is synthesized mainly by monocytes in peripheral blood and that it could potentially bind to sugar structures on microorganisms. The aim of the present investigations was to isolate ficolin from human plasma by affinity chromatography on immobilized sugars. A human serum protein was identified in the GlcNAc eluate from GlcNAc-Sepharose which migrated as a polypeptide of approx. 40 kDa on SDS-PAGE under reducing conditions and was, after further purification by FPLC on a mono-Q column, shown to have an identical N-terminal sequence, over the first 14 residues, to P35, a plasma protein having similar sequence and domain organisation to ficolin. This protein, named the ficolin-like protein, was shown to be sensitive to collagenase and similar to P35 in that it was also disulphide-linked into an oligomer of approx. 320 kDa. However, unlike P35, its binding to GlcNAc was independent of Ca2+. Gel-filtration studies showed that this ficolin-like protein also had a molecular weight of approx. 320 kDa under non-dissociating conditions. During the course of this study this ficolin-like protein was found to simply bind to CNBr-activated Sepharose which had been inactivated with Tris, and from which it could be eluted with GlcNAc. This ficolin-like protein was also shown to bind to GlcNAc, but not to mannose and maltose. The functional significance of the unusual binding property of this ficolin-like protein is not clear, but it has facilitated the development of a simple method for its purification.

Acetylglucosamine↗

PubMed1997

Anatomic considerations of the lumbar isthmus.

STUDY DESIGN: A morphometric study of lumbar isthmus from L1 to L5 on 30 dried lumbar spines was conducted. OBJECTIVE: To provide anatomic data about the lumbar isthmus and to quantitatively evaluate structural features of the lumbar isthmus and its relationship to adjacent anatomic structures. SUMMARY OF BACKGROUND DATA: There are very few anatomic studies about the lumbar isthmus, and no study describes the relationship of the lumbar isthmus to its adjacent structures. METHODS: Direct measurements using digital calipers and a goniometer were taken from 30 dried lumbar spines. Anatomic evaluation focused on the lumbar isthmus and its related structures, the isthmus pedicle, and superior and inferior facets. Seven linear and four angular parameters of the lumbar isthmus were determined. RESULTS: The length of the superior edge of the isthmus gradually increased from L2 to L5 (from 8.22 +/- 1.43 mm at L2 to 10.44 +/- 1.90 mm at L5), and that of its inferior edge progressively decreased from L2 to L5 (from 8.67 +/- 1.76 mm at L2 to 6.34 +/- 1.74 mm at L5). The superoinferior diameter of the isthmus decreased from L3 to L5 (from 13.87 +/- 1.77 mm at L3 to 13.26 +/- 2.49 mm at L5). The superior edge of the isthmus was the thinnest at L4 (1.62 +/- 0.58 mm), and its thickness inferiorly increased from L1 to L5 (from 6.71 +/- 1.47 mm at L1 to 7.76 +/- 1.08 mm at L5). The medial and caudal inclination of the isthmus with respect to the pedicle gradually increased from L1 to L5 (from 112.3 degrees +/- 13.8 degrees at L1 to 119.2 degrees +/- 11.2 degrees at L5 medial inclination and from 132.5 degrees +/- 8.8 degrees at L2 to 139.0 degrees +/- 12.1 degrees at L5 caudal inclination, respectively). The dimensions of the lumbar isthmus were positively correlated to dimensions of the pedicle and orientations of the facets. CONCLUSIONS: This study provides detailed anatomic data of the lumbar isthmus. Anatomic parameters of the lumbar isthmus are related to the vertebral levels and have a significant correlation with the angles of the facets and the dimensions of the pedicles. The vulnerability of the pars interarticularis of the fifth lumbar vertebra has been anatomically confirmed.

Analysis of Variance↗

PubMed1997

Anterior iliac crest bone graft. Anatomic considerations.

STUDY DESIGN: A morphologic study of the anterior part of the iliac crest was performed. OBJECTIVE: To define the anatomic characteristics of the anterior part of the ilium and to determine an optimal area to harvest the iliac bone graft from the anterior iliac crest. SUMMARY OF BACKGROUND DATA: Stress fracture or avulsion fracture of the anterior cut for anterior iliac crest graft have been noted previously. However, there is insufficient published information on the morphology of the anterior part of the ilium relative to the optimal location of harvesting the bone graft. METHODS: Direct measurements using digital calipers were taken from 30 dried human pelves and 10 cadaveric pelves. The thickness of the anterior part of the ilium was measured, with different starting points on the iliac crest. The length of the bicortical iliac bone graft also was determined. RESULTS: The thickest portion of the ilium was 18.9 +/- 2.3 mm at the iliac tubercle, which was 45% thicker than at a point 3 cm posterior to the anterior superior iliac spine. The thick region of the anterior iliac crest extended 54.0 +/- 10.2 mm posteriorly from a point 3 cm posterior to the anterior superior iliac spine. The mean length of a 10 mm thick bicortical iliac tubercle bone graft was 36.8 +/- 8.7 mm. CONCLUSIONS: The region around the iliac tubercle is suitable for harvesting bicortical or tricortical bone graft.

Bone Transplantation↗

PubMed1997

Differential induction of growth arrest inducible genes by selenium compounds.

The effects of two types of selenium compounds on the expression levels of growth arrest and DNA damage-inducible (gadd) genes and on selected cell death genes were examined in mouse mammary MOD cells to test the hypothesis that the diversity of selenium-induced cellular responses to these compounds could be distinguished by unique gene expression patterns. Whereas the expression patterns of known cell death-related genes (bcl-2 and bax) were not informative with respect to the cellular response patterns upon exposure to selenium compounds, time-dependent and selenium species-specific induction patterns were observed for gadd34, gadd45 and gadd153 genes. It was also observed that the MOD cells expressed a truncated p53 transcript but no detectable immunoreactive P53 protein, indicating a null p53 phenotype. The fact that selenium compounds induced growth arrest and death of these cells and that these compounds induced specific patterns of expression of gadd genes indicates that these genes may mediate some selenium-induced cellular responses. The findings further imply that selenium compounds may be effective chemopreventive agents for human breast carcinogenesis, in which p53 mutations are frequent.

Animals↗

PubMed1997

The effects of imidazole binding on the conformation of cytochrome c.

Many individual protons exhibit different chemical shifts in Im-cyt c and cyt c, reflecting diamagnetic shift effects as a result of structure change, and in addition contact and pseudocontact shifts that occur only in the paramagnetic oxidized form. To estimate the chemical shift differences caused by structure change, we removed the pseudocontact shift contribution. The anisotropy and direction of the magnetic susceptibility anisotropy tensor were determined. There was evidence for conformational changes induced by the breakage of Fe-S bond. It was concluded that the Im-cyt c had undergone a rearrangement of several regions forming the heme pocket of the protein. The hydrogen-bond network in the heme cavity was affected by the substitution.

Cytochrome c Group↗

PubMed1997

Thermal unfolding of the N-terminal RNA binding domain of the human U1A protein studied by differential scanning calorimetry.

Thermal unfolding of the N-terminal RNA binding domain of human U1A protein (RBD1) and several variants has been observed by differential scanning calorimetry. Unfolding of the 95 amino acid domain is reversible and cooperative between pH 2.0 and 2.8 in 40 mM glycine, with a heat capacity for the transition of 1.2 kcal mol-1 K-1, and an unfolding free energy of 4.0 kcal mol-1 at pH 2.3 and 25 degrees C. At higher pH, thermal unfolding is irreversible. In contrast, unfolding of the protein by guanidine hydrochloride denaturation at pH 2.3 and pH 7.0 is reversible, with unfolding free energies of 6.6 and 9.0 kcal mol-1, respectively. DSC experiments show that RBD variants in which the N-terminal tail is truncated, or in which a functional loop is substituted, have altered unfolding free energies but little variation in their heat capacities of transition.

Amino Acid Sequence↗