Biomedical subjects

B Yu

Publications and source records attributed to B Yu.

At least 109 records · Page 6Linked to original sources

PubMed1998

[The effects of Chinese medicine herb mixture on cell-mediated immune functions and four kinds of acute-phase reaction proteins in burn patients].

OBJECTIVE: To search for immunomodulators to improve postburn immune function disorder. METHOD: We studied the Chinese medicinal herbs. On the basis of previous data, we prepared a kind of Chinese medicinal herbal mixture and studied its effects in vivo and in vitro. RESULT: The mixture could restore the cell-mediated immune response such as the production of interleukin 2 and the T cell proliferative ability, and could also adjust the levels of serum acute-phase reaction proteins, i.e, haptoglobin, prealbumin, transferrin and alpha 1-acid glycoprotein. CONCLUSION: The Chinese herbal mixture showed immune regulatory effects on body defence imbalance and also on acute phase reaction proteins in burn patients.

Acute-Phase Proteins↗

PubMed1998

[Investigation on resources and commodities of Chinese medicinal herbs of Jili].

OBJECTIVE: To make clear the current situation of application of the Chinese medicinal herbs of Jili. METHOD: The medicinal resources and commodities of the berbs in some provinces and cities in China were investigated. RESULT: The species Tribulus terrestris included in is widely distributed in China. The fruit of T. terrestris which is widely used in China as a traditional medicine is commonly called Yingjili. Being only the fruit of Atriplex entralasiatica Ruanjili is produced mainly in Shandong Province and customarily used as Fructus Tribuli in some areas of Shandong and Hebei Provinces. CONCLUSION: The current situation of medicinal application of Jili basically conforms to the requirements of . The main variety is Yingjili.

China↗

PubMed1998

Corticotropin-releasing factor increases dihydropyridine- and neurotoxin-resistant calcium currents in neurons of the central amygdala.

Corticotropin-releasing factor (CRF) is an important mediator of stress responses in the brain, and CRF receptors and CRF-containing neurons and terminals are located within the central nucleus of the amygdala (CeA). CeA neurons possess multiple types of Ca++ channels, including L, N and Q types and a current resistant to saturating concentrations of dihydropyridine and neurotoxin antagonists. In this study, we used whole-cell patch-clamp techniques to study the effects of CRF on whole-cell Ca++ current (ICa) in acutely dissociated CeA neurons and determine components of the current affected. CRF (1-400 nM) increased the peak of the ICa in approximately 50% of the CeA neurons recorded. In the remaining neurons, CRF had little effect. The CRF-induced increase in the ICa was concentration dependent and the estimated EC50 value was 14.9 nM. CRF (50 nM) increased the peak ICa by 25 +/- 5% (n = 9). CRF produced an increase in both the transient and the steady state current but did not shift the peak of the current-voltage relationship. CRF did not affect the voltage dependence of activation and inactivation, and the CRF effect on ICas was not significantly different when the neuron was held at -80 or -40 mV. The competitive CRF receptor antagonist (alpha-helical CRF9-41, 3 microM) blocked the CRF-induced increase in ICa, suggesting that the effect of CRF is receptor mediated. CRF (50 nM) enhanced the ICa (20 +/- 3%) in the presence of saturating concentrations of the L-type blocker nimodipine and neurotoxin N- and Q-type blockers omega-conotoxin GVIA and omega-conotoxin MVIIC. We conclude that CRF increased, through a receptor mechanism, dihydropyridine- and neurotoxin-resistant current(s) in CeA neurons.

Amygdala↗

PubMed1998

Prenatal diagnosis for thalassaemia in a multicultural society.

The provision of a prenatal diagnosis service for thalassaemia is becoming more demanding. In an ethnically-diverse community, the number of mutations has increased. Requests for prenatal testing continue to come at advanced stage in pregnancy, often without the underlying mutation having been identified. Although controls are included in PCR assays, errors can still occur. The alternative to DNA testing, i.e., an alpha/beta globin chain synthesis ratio on a fetal blood sample, is now less readily available. In the circumstances described, the laboratory must adopt a more efficient and reliable approach to DNA mutation analysis. With currently available technology, this improvement is more likely to come through increased automation. To achieve this aim, we have moved to capillary electrophoresis. With capillary electrophoresis we are able to use a PCR-based screening strategy which can detect up to 11 beta thalassaemia mutations. The actual prenatal test is undertaken using two independent PCRs thereby reducing the potential for error. Despite the advantages of PCR, approximately 12 per cent of beta thalassaemia and about nine per cent of alpha thalassaemia cases require further study in our experience. In this situation, capillary electrophoresis has again proven helpful since a DNA scanning approach, such as single strand conformation polymorphism, can be automated to identify the region of DNA to be sequenced.

Asia, Southeastern↗

PubMed1997

The Ca2+-dependent binding of calmodulin to an N-terminal motif of the heterotrimeric G protein beta subunit.

Ca2+ ion concentration changes are critical events in signal transduction. The Ca2+-dependent interactions of calmodulin (CaM) with its target proteins play an essential role in a variety of cellular functions. In this study, we investigated the interactions of G protein betagamma subunits with CaM. We found that CaM binds to known betagamma subunits and these interactions are Ca2+-dependent. The CaM-binding domain in Gbetagamma subunits is identified as Gbeta residues 40-63. Peptides derived from the Gbeta protein not only produce a Ca2+-dependent gel mobility shifting of CaM but also inhibit the CaM-mediated activation of CaM kinase II. Specific amino acid residues critical for the binding of Gbetagamma to CaM were also identified. We then investigated the potential function of these interactions and showed that binding of CaM to Gbetagamma inhibits the pertussis toxin-catalyzed ADP-ribosylation of Galphao subunits, presumably by inhibiting heterotrimer formation. Furthermore, we demonstrated that interaction with CaM has little effect on the activation of phospholipase C-beta2 by Gbetagamma subunits, supporting the notion that different domains of Gbetagamma are responsible for the interactions of different effectors. These findings shed light on the molecular basis for the interactions of Gbetagamma with Ca2+-CaM and point to the potential physiological significance of these interactions in cellular functions.

Adenosine Diphosphate Ribose↗

PubMed1997

Characterization of a Goalpha mutant that binds xanthine nucleotides.

Several GTP binding proteins, including EF-Tu, Ypt1, rab-5, and FtsY, and adenylosuccinate synthetase have been reported to bind xanthine nucleotides when the conserved aspartate residue in the NKXD motif was changed to asparagine. However, the corresponding single Goalpha mutant protein (D273N) did not bind either xanthine nucleotides or guanine nucleotides. Interestingly, the introduction of a second mutation to generate the Goalpha subunit D273N/Q205L switched nucleotide binding specificity to xanthine nucleotide. The double mutant protein GoalphaD273N/Q205L (GoalphaX) bound xanthine triphosphate, but not guanine triphosphate. Recombinant GoalphaX (GoalphaD273N/Q205L) formed heterotrimers with betagamma complexes only in the presence of xanthine diphosphate (XDP), and the binding to betagamma was inhibited by xanthine triphosphate (XTP). Furthermore, as a result of binding to XTP, the GoalphaX protein underwent a conformational change similar to that of the activated wild-type Goalpha. In transfected COS-7 cells, we demonstrate that the interaction between GoalphaX and betagamma occurred only when cell membranes were permeabilized to allow the uptake of xanthine diphosphate. This is the first example of a switch in nucleotide binding specificity from guanine to xanthine nucleotides in a heterotrimeric G protein alpha subunit.

Amino Acid Sequence↗

PubMed1997

The limits of random fingerprinting.

Various random fingerprinting methods are sometimes used to detect overlap between pairs of clones as a first step toward producing a minimal tiling path of clones for subsequent mapping and sequencing efforts. This paper evaluates and compares various statistical procedures for detecting pairwise overlap between clones when the fingerprints arise from any random process meeting simple, plausible assumptions about the relationship between overlap and the resulting fingerprint. Examples of such random processes include, but are not limited to, large-scale hybridization procedures designed to prepare tiling paths of clones for subsequent large-scale genomic sequencing. Our goals are to assess how well random fingerprinting can possibly detect overlap, to assess the effects of inevitable fingerprinting errors on statistical detection, to determine how one can make the best use of the data random fingerprinting provides, and to evaluate how well simple, heuristic techniques for overlap detection compare to more complex, likelihood-based approaches. The paper provides a quantitative assessment of the ability of any random fingerprinting procedure to detect various proportions of clonal overlap and shows the extent to which a small amount of experimental error will vitiate the performance of such techniques. The paper outlines a simple approximation method for constructing Bayesian overlap detectors, while concluding that detectors constructed from linear combinations of fingerprint data can be designed that will perform nearly as well as more complex, likelihood-based approaches.

DNA Fingerprinting↗

PubMed1997

Activation of protein kinase C (alpha, beta, and zeta) by insulin in 3T3/L1 cells. Transfection studies suggest a role for PKC-zeta in glucose transport.

We presently studied (a) insulin effects on protein kinase C (PKC) and (b) effects of transfection-induced, stable expression of PKC isoforms on glucose transport in 3T3/L1 cells. In both fibroblasts and adipocytes, insulin provoked increases in membrane PKC enzyme activity and membrane levels of PKC-alpha and PKC-beta. However, insulin-induced increases in PKC enzyme activity were apparent in both non-down-regulated adipocytes and adipocytes that were down-regulated by overnight treatment with 5 microM phorbol ester, which largely depletes PKC-alpha, PKC-beta, and PKC-epsilon, but not PKC-zeta. Moreover, insulin provoked increases in the enzyme activity of immunoprecipitable PKC-zeta. In transfection studies, stable overexpression of wild-type or constitutively active forms of PKC-alpha, PKC-beta1, and PKC-beta2 failed to influence basal or insulin-stimulated glucose transport (2-deoxyglucose uptake) in fibroblasts and adipocytes, despite inhibiting insulin effects on glycogen synthesis. In contrast, stable overexpression of wild-type PKC-zeta increased, and a dominant-negative mutant form of PKC-zeta decreased, basal and insulin-stimulated glucose transport in fibroblasts and adipocytes. These findings suggested that: (a) insulin activates PKC-zeta, as well as PKC-alpha and beta; and (b) PKC-zeta is required for, and may contribute to, insulin effects on glucose transport in 3T3/L1 cells.

3T3 Cells↗

PubMed1997

Lipopolysaccharide binding protein and soluble CD14 catalyze exchange of phospholipids.

Lipopolysaccharide binding protein (LBP) is a plasma protein known to facilitate the diffusion of bacterial LPS (endotoxin). LBP catalyzes movement of LPS monomers from LPS aggregates to HDL particles, to phospholipid bilayers, and to a binding site on a second plasma protein, soluble CD14 (sCD14). sCD14 can hasten transfer by receiving an LPS monomer from an LPS aggregate, and then surrendering it to an HDL particle, thus acting as a soluble "shuttle" for an insoluble lipid. Here we show that LBP and sCD14 shuttle not only LPS, but also phospholipids. Phosphatidylinositol (PI), phosphatidylcholine, and a fluorescently labeled derivative of phosphatidylethanolamine (R-PE) are each transferred by LBP from membranes to HDL particles. The transfer could be observed using recombinant LBP and sCD14 or whole human plasma, and the plasma-mediated transfer of PI could be blocked by anti-LBP and partially inhibited by anti-CD14. sCD14 appears to act as a soluble shuttle for phospholipids since direct binding of PI and R-PE to sCD14 was observed and because addition of sCD14 accelerated transfer of these lipids. These studies define a new function for LBP and sCD14 and describe a novel mechanism for the transfer of phospholipids in blood. In further studies, we show evidence suggesting that LBP transfers LPS and phospholipids by reciprocal exchange: LBP-catalyzed binding of R-PE to LPS x sCD14 complexes was accompanied by the exit of LPS from sCD14, and LBP-catalyzed binding of R-PE to sCD14 was accelerated by prior binding of LPS to sCD14. Binding of one lipid is thus functionally coupled with the release of a second. These results suggest that LBP acts as a lipid exchange protein.

Acute-Phase Proteins↗

PubMed1997

Reproducibility of the kinematics and kinetics of the lower extremity during normal stair-climbing.

The purpose of this study was to examine the intrasubject reproducibility of the kinematic and kinetic measures of the lower extremity during normal stair-climbing. Three-dimensional video and force-plate data were collected for three trials per subject during each of three conditions: ascending, descending, and level walking. Three-dimensional angles and moments of the ankle, knee, and hip joints were calculated. The coefficient of multiple correlation was used to determine the intrasubject reproducibility of joint angles and resultant moments. Analysis of variance with repeated measures was conducted to compare the magnitudes of the coefficients between different steps, different joints, and different joint functions. The results showed that (a) generally, the kinematic and kinetic measures of normal subjects climbing stairs were reproducible; (b) the kinetic measures during the transition steps from level walking to ascending and from descending to level walking were significantly less reproducible than those during the other steps; (c) the data from the sagittal plane were more reproducible than those from the other two planes; and (d) the kinetic measures were more reproducible than the kinematic measures, especially for abduction-adduction and internal-external rotation.

Adult↗

PubMed1997

Parameters for modeling the upper extremity.

The purpose of this paper was to provide parameters for the development of a musculoskeletal model of the upper extremity. Five upper extremity specimens were obtained from four fresh cadavers. Anthropometric measures were obtained for each cadaver. Segment inertial parameters were estimated for each specimen from anthropometric measures of the cadaver from which the specimen was obtained. The three-dimensional kinematics of the humerus, ulna, and radius in different movements of the glenohumeral, humeroulnar and ulnoradial joints were measured for each specimen using of the 3Space tracking system (Isotrack, Polhemus). The instantaneous rotation center of the glenohumeral joint and the instantaneous rotation axes of elbow flexion and forearm pronation were determined for each specimen from the kinematic data. The specimens were dissected and the muscle origins and insertions and bony structures needed in upper extremity modeling were digitized using the 3Space system. The shapes of muscle origins and insertions were estimated. Muscle length, volume and pennation angle were measured for the estimation of physiological cross-sectional areas of each muscle. The results, which are given for one specimen, showed that the rotation center of the glenohumeral joint was very close to the geometric center of the joint with a mean distance of 4 mm. The mean angle between the flexion-extension and pro-supination axes of the elbow joint was 94 degrees. The minimum distance between these two axes was about 4 mm.

Aged↗

PubMed1997

Valgus-varus motion of the knee in normal level walking and stair climbing.

OBJECTIVE: The knee valgus-varus moment and the knee angles were compared between normal level walking and stair climbing. DESIGN: Ten healthy subjects were tested for ascent, descent, and level walking. BACKGROUND: An understanding of the normal valgus-varus motion of the knee during stair climbing is needed to apply biomechanical analysis of stair climbing as a evaluation tool for knee osteoarthritis patients. METHODS: A motion analysis system, three force plates, and a flight of stairs were used to collect kinematic and kinetic data. The knee angles and moments were calculated from the collected kinematic and kinetic data. RESULTS: The knee varus angle for the maximum knee valgus moments in stair climbing was significantly greater than that in level walking. The knee valgus moment was significantly correlated to ground reaction forces and knee valgus-varus angle during stair climbing and level walking. CONCLUSIONS: There is a coupling between the knee valgus-varus motion and flexion-extension motion. Ground reaction forces are the major contributors to the within-subject variation in the knee valgus-varus moment during stair climbing and level walking. The knee valgus-varus angle is a major contributor to the between-subject variation in the knee valgus moment during stair climbing and level walking.

Journal Article↗

PubMed1997

Sudden cardiac death in familial hypertrophic cardiomyopathy: are "benign" mutations really benign?

Familial hypertrophic cardiomyopathy (FHC) is an autosomal dominant disorder characterised predominantly by left ventricular hypertrophy and sudden cardiac death. Mutations in the cardiac beta-myosin heavy chain gene have been identified in several families and designated as "benign" or "malignant". We describe a family (family L) with a "benign" mutation in which early sudden cardiac death has occurred. The family was studied by clinical, electrocardiographic and echocardiographic assessment. DNA analysis involved screening for the six most common cardiac beta-myosin heavy chain gene mutations using allele specific oligonucleotide probes and restriction enzyme analysis. The Val606Met missense mutation was found. This mutation has been described in four families as being "benign" since it was associated with low penetrance and a near normal life span. Sudden cardiac death was an infrequent finding. In contrast, family L has a more malignant clinical picture with one sudden death in three affected individuals. The proband died suddenly at age 14 years during exercise. Designating gene mutations in FHC as benign or malignant has major clinical implications. As these mutations have only been described in a limited number of families, caution needs to be taken when interpreting genotype-phenotype correlations in this disorder.

Cardiomyopathy, Hypertrophic↗

PubMed1997

First trial of home ECG and blood pressure telemonitoring system in Macau.

OBJECTIVE: To determine the feasibility of home monitoring of patients with cardiac disease or hypertension. METHODS: An improved home electrocardiographic and blood pressure telemonitoring system linked to a central workstation was tested in 10 patients in Macau for 3 months. RESULTS: The total number of connections was 1377. Of the automatic alarm connections, 32.5% were false positive, with the percentage of false positives ranging from 7.6 to 54.6 for different patients. Both patients and physicians found the system easy to use. CONCLUSIONS: Further investigation is required to match the number of patients with the system capacity. A more robust dysrhythmia detection algorithm is needed to reduce the number of false alarms. Nevertheless, the results were sufficiently good that the trial is being expanded.

Blood Pressure Determination↗

PubMed1997

Dihydropyridine- and neurotoxin-sensitive and -insensitive calcium currents in acutely dissociated neurons of the rat central amygdala.

The central amygdala (CeA) is an area involved in emotional learning and stress, and identification of Ca2+ currents is essential to understanding interneuronal communication through this nucleus. The purpose of this study was to separate and characterize dihydropyridine (DHP)- and neurotoxin-sensitive and -resistant components of the whole cell Ca2+ current (ICa) in acutely dissociated rat CeA neurons with the use of whole cell patch-clamp recording. Saturating concentrations of nimodipine (NIM, 5 microM), a DHP antagonist, blocked 22% of ICa: this NIM-sensitive (L-type) current was recorded in 68% of CeA neurons. The DHP agonist Bay K 8644 (5 microM) produced a 36% increase in ICa in a similar proportion of CeA neurons (70%). omega-Conotoxin GVIA (CgTx GVIA, 1 microM) in saturating concentrations inhibited 30% of ICa, whereas omega-agatoxin IVA (Aga IVA, 100 nM), in concentrations known to block P-type currents, did not affect ICa. Higher concentrations of Aga IVA (1 microM) alone reduced ICa by 34%, but in the presence of NIM (5 microM) and CgTx GVIA (1 microM) blocked only 18% of ICa. omega-Conotoxin MVIIC (CgTx MVIIC, 250 nM) reduced ICa by 13% in the presence of CgTx GVIA (1 microM). Application of NIM (5 mM), CgTx GVIA (1 microM); and Aga IVA (1 microM) blocked approximately 67% of ICa. A similar portion (63%) of Ca2+ current was blocked with CgTx MVIIC (250 nM) in the presence of NIM (5 microM) and CgTx GVIA (1 microM). The current resistant to NIM and the neurotoxins represented 37% of ICa, whereas in neurons not having L-type currents the resistant current made up approximately 53% of ICa (49 +/- 2%, mean +/- SE). The resistant current activated at around -40 mV and peaked at approximately 0 mV with half-activation and -inactivation potentials of -17 and -58 mV and slopes for activation and inactivation of -5 and 13 mV, respectively. The resistant current was sensitive to Cd2+ (IC50 = 2.5 microM) and Ni2+ (IC50 = 86 microM), was larger in Ca2+ than in Ba2+ (ratio = 1.31:1), and showed a moderate rate of decay. In summary, our results show that the high-voltage-activated calcium current in rat CeA neurons is composed of at least four pharmacologically distinct components: L-type current (NIM sensitive, 22%), N-type current (CgTx GVIA sensitive, 30%), Q-type current [Aga IVA (1 microM) and CgTx MVIIC sensitive, approximately 13-18%], and a resistant current (Non-L, -N, and -Q current, 33 approximately 37%), amounting to 37-53% of the total current. The resistant current has some electrophysiological and pharmacological characteristics in common with doe-1, alpha 1E, and R-type calcium currents, but remains unclassified.

Amygdala↗

PubMed1997

The morphological changes of intestinal mucosa in growing rabbits.

The study aimed to increase understanding of digestive function from the development of the digestive tract from suckling to maturity in rabbits. The relative weights of the digestive tract (in relation to body weight) in different segments increase linearly during the rapid growth period between 2 and 8 weeks of age, thereafter intestinal weight gain is slower. An underdeveloped mucosal histology was observed in the hindgut of suckling rabbits at 2 weeks compared with 4 weeks of age. From SEM micrographs, the small intestinal mucosal villi look more slender and finger-like in the suckling period, thereafter becoming broader or tongue-like or plate-shaped in mature rabbits. The micrographs showed a compact arrangement in the underdeveloped hindgut mucosa at 2 weeks, but after weaning as hindgut fermentation becomes significant the mucosa increased in surface area.

Aging↗

PubMed1997

A home electrocardiography and blood pressure telemonitoring system.

A home electrocardiography (ECG) and blood pressure telemonitoring system for cardiac patients was installed in the Macau region. The monitoring centre was established in the emergency unit at the Government Hospital of Macau. The first users were 10 cardiovascular patients selected by a physician. The average age of these users was 61 years (range 30-78). The results of a three-month trial showed that the system was easy to operate and technically reliable. It was found to be helpful for cardiac patients. The most significant problem during the trial was electrical noise from the ECG electrodes.

Adult↗

PubMed1997

[HLA-DQA1 genes involved in genetic susceptibility to rheumatic fever and rheumatic heart disease in southern Hans].

The incidence of rheumatic fever (RF) or rheumatic heart disease (RHD) is high in southern China. We studied the genetic susceptibility of HLA-DQA1 alleles to RF or RHD with emphasis on the mechanisms 106 unrelated healthy individuals and 54 patients with RF or RHD of Chinese Han nationality in Guangdong were included. DNA extraction from various biological material using phenol/chloroform method and HLA-DQA1 genotyping by PCR-PAGE and then with silver dyeing was used to show the electrophoretic patterns. A total 6 alleles of HLA-DQA1 were found. Increased allele frequencies of DQA1*0101 (31.48%, RR = 2.89, P < 0.005, EF = 0.206) and decreased allele frequencies of DQA1*0102 (1.85%, RR = 0.106, P < 0.005, PF = 0.134) were observed. Two increased genotyping of HLA-DQA1 (DQA1*0101/0301, chi 2 = 8.84, P < 0.005 and DQA1*0101/0401, chi 2 = 6.23, P < 0.0025) and decreased genotyping of DQA1*0102/0301 (chi 2 = 11.98, P < 0.005) were also observed. These findings suggested that DQA1*0101 contribute to genetic susceptibility for RF or RHD in Guangdong hans while DQA1*0102 to its genetic resistance. Digesting the genotyping of HLA-DQA1 may provide scientific basis for finding susceptible individuals to RF or RHD. Using PCR-PAGE and silver dyeing technique, a new genotyping method for HLA-DQA1, which is simple sensitive and precise, was established and applied.

Adolescent↗