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Biomedical subjects

M J Wang

Publications and source records attributed to M J Wang.

At least 19 recordsLinked to original sources
PubMed2002

Transoesophageal echocardiographic monitoring of pulmonary venous obstruction induced by sternotomy closure during infant heart transplantation.

A case of an infant receiving orthotopic heart transplantation with over-sized donor heart was reported. Left lower pulmonary venous obstruction after sternotomy closure was detected by transoesophageal echocardiography (TOE) and the decision to delay sternal closure was made and the clinical outcome was very satisfactory. The usefulness of intraoperative TOE monitoring and postoperative TOE follow-up for infant heart transplantation, especially in those cases of size mismatch, was well demonstrated.

Echocardiography, Transesophageal↗
PubMed2001

Neurokinin B potentiates ATP-activated currents in rat DRG neurons.

This study aimed to explore whether NKB could modulate the responses mediated by ATP receptor (P2X purinoceptor). Whole-cell patch clamp and repatch experiments were performed on cultured rat DRG neurons. The majority of neurons examined were sensitive both to ATP and to NKB (77.1%, 54/70). NKB preapplied could potentiate ATP-activated currents (I(ATP)) markedly; this effect was concentration-dependent and could be blocked by SR 142801, an NK3 receptor antagonist. Preapplication of 0.001, 0.01, 0.1 and 1.0 microM NKB increased ATP-activated currents by 55.1+/-18.8, 75.2+/-17.4, 84.1+/-18.8 and 81.0+/-21.7%, respectively. The concentration-response curves for ATP with and without preapplication of NKB show that: (1) preapplication of NKB shifted the curve upwards; (2) the maximal amplitude of I(ATP) with NKB preapplication increased by 78.5%, while the threshold value remained unchanged; (3) the EC(50) values of the two curves were very close (44 vs. 42 microM). Intracellular dialysis of H-7 by using repatch clamp technique could block the potentiation of I(ATP) by NKB. It suggests that this potentiating effect was caused by phosphorylation of ATP receptor, which resulted from the activation of G protein coupled NK3 receptor and consequential intracellular signal transduction cascade.

Adenosine Triphosphate↗
PubMed2001

Energy loss of fast quarks in nuclei.

We report an analysis of the nuclear dependence of the yield of Drell-Yan dimuons from the 800 GeV/c proton bombardment of 2H, C, Ca, Fe, and W targets. Employing a new formulation of the Drell-Yan process in the rest frame of the nucleus, this analysis examines the effect of initial-state energy loss and shadowing on the nuclear-dependence ratios versus the incident proton's momentum fraction and dimuon effective mass. The resulting energy loss per unit path length is -dE/dz = 2.32+/-0.52+/-0.5 GeV/fm. This is the first observation of a nonzero energy loss of partons traveling in a nuclear environment.

Journal Article↗
PubMed2001

Resveratrol inhibits interleukin-6 production in cortical mixed glial cells under hypoxia/hypoglycemia followed by reoxygenation.

Reactive oxygen intermediates (ROIs) are important mediators of a variety of pathological processes, including inflammation and ischemia/reperfusion injury. Cytokines and chemokines are detected at mRNA level in human and animal ischemic brains. This suggests that hypoxia/reoxygenation may induce cytokine production through generation of ROIs. In this study, we investigated the cytokine induction and inhibition by antioxidants in rat cortical mixed glial cells exposed to in vitro ischemia-like insults (hypoxia plus glucose deprivation). The results showed that interleukin-6 (IL-6) mRNA and protein, but not tumor necrosis factor-alpha (TNF-alpha) or interleukin-1beta (IL-1beta), were induced during hypoxia/hypoglycemia followed by reoxygenation in the mixed glial cells. The accumulation of IL-6 mRNA was induced as early as 15 min after hypoxia/hypoglycemia and its level was further increased after subsequent reoxygenation. Among the antioxidants studied, only resveratrol suppressed IL-6 gene expression and protein secretion in mixed glial cultures under hypoxia/hypoglycemia followed by reoxygenation. These findings suggest that resveratrol might be useful in treating ischemic-induced inflammatory processes in stroke.

Animals↗
PubMed2001

Determining the maximum acceptable work duration for high-intensity work.

The aim of this study was to determine the maximum acceptable work duration (MAWD) for high-intensity work. Thirty young individuals participated in this study. Their maximum oxygen uptake (VO2max) and maximum work rate (MWR) were assessed first. Each subject then performed two cycling tests (60% and 70% MWR) on two separate days. Oxygen uptake and heart rate data were collected throughout the test. The results indicate that the MAWD in the 60% MWR test (18.8 min) was about threefold greater than the MAWD in the 70% MWR test (6.5 min). The MAWD was inversely correlated with the relative workload indices: relative oxygen uptake (RVO2; r = -0.82, P < 0.001) and relative heart rate (RHR; r = -0.79, P < 0.001). The RVO2 was defined as the elevation in oxygen uptake from the resting level as a percentage of the difference between maximum and resting oxygen uptake. The RHR was defined as the elevation in heart rate from the resting level as a percentage of the difference between maximum and restingheart rate. Furthermore, more than 80% of the variations were explained by the exponential decrease regression model for predicting MAWD using the above two variables. The findings of this study can provide useful information for the design of high-intensity jobs.

Adult↗
PubMed2001

The effects of container design and stair climbing on maximal acceptable lift weight, wrist posture, psychophysical, and physiological responses in wafer-handling tasks.

Despite the high level of automation in semiconductor manufacturing processes, many manual operations are still involved in the workplace. Due to inadequate human-machine interface design, stairs are frequently used to help operators perform wafer-handling tasks. This study was designed to evaluate the effects of climbing stairs and carrying wafer containers (pods) on psychophysical responses (maximal acceptable weight of lift--MAWL, and ratings of perceived exertion--RPE), physiological responses (oxygen consumption--VO2, and heart rate--HR), and wrist posture (ulnar and radial deviations). Each of 12 subjects (six males and six females) performed six sessions (3 climbing stairs x 2 pods types). The results indicate that climbing stairs had a significant influence on MAWL and VO2 (p<0.01). The type of pod effect on wrist posture was significant (p<0.01). Gender effect differences on MAWL, VO2 and wrist posture were also significant (p<0.05). Job design implications are discussed.

Adult↗
PubMed2001

Dehydroepiandrosterone inhibits lipopolysaccharide-induced nitric oxide production in BV-2 microglia.

Levels of dehydroepiandrosterone (DHEA) and its sulfated derivative (DHEAS) decline during aging and reach even lower levels in Alzheimer's disease (AD). DHEA is known to exhibit a variety of functional activities in the CNS, including an increase of memory and learning, neurotrophic and neuroprotective effects, and the reduction of risk of age-related neurodegenerative disorders. However, the influence of DHEA on the immune functions of glial cells is poorly understood. In this study, we investigated the effect of DHEA on activated glia. The production of inducible nitric oxide synthase (iNOS) was studied in lipopolysaccharide (LPS)-stimulated BV-2 microglia, as a model of glial activation. The results showed that DHEA but not DHEAS significantly inhibited the production of nitrite in the LPS-stimulated BV-2 cell cultures. Pretreatment of BV-2 cells with DHEA reduced the LPS-induced iNOS mRNA and protein levels in a dose-dependent manner. The LPS-induced iNOS activity in BV-2 cells was decreased by the exposure of 100 microM DHEA. Moreover, DHEA suppressed iNOS gene expression in LPS-stimulated BV-2 cells did not require de novo synthesis of new proteins or destabilize of iNOS mRNA. Since DHEA is biosynthesized by astrocytes and neurons, our findings suggest that it might have an important regulatory function on microglia.

Animals↗
PubMed2001

The addition of morphine prolongs fentanyl-bupivacaine spinal analgesia for the relief of labor pain.

UNLABELLED: The combination intrathecal fentanyl (25 microg) and bupivacaine (2.5 mg) provides effective labor analgesia for approximately 90 minutes. The purpose of this prospective, randomized, double-blinded investigation was to determine if the addition of morphine (150 microg) to the intrathecal combination of fentanyl (25 microg) and bupivacaine (2.5 mg) would prolong labor analgesia. By using the combined spinal epidural technique, 95 healthy primiparous laboring women in early labor received 2 mL of one of the two intrathecal study solutions, either FB (n = 48): fentanyl (25 microg) and bupivacaine (2.5 mg); or FBM (n = 47): fentanyl (25 microg) and bupivacaine (2.5 mg) plus morphine (150 microg). The mean duration of labor analgesia was significantly longer in the FBM group than in the FB group (252 +/- 63 min vs 148 +/- 44 min, P < 0.01). There were no significant differences between the two groups regarding the sensory levels, the incidence of nausea, vomiting, pruritus, hypotension, or operative delivery. In conclusion, the addition of 150 microg of morphine to the intrathecal combination of fentanyl plus bupivacaine prolonged the duration of labor analgesia duration without increasing adverse effects. IMPLICATIONS: The addition of morphine (150 microg) to intrathecal fentanyl (25 microg) and bupivacaine (2.5 mg) prolongs the duration of labor analgesia duration without increasing adverse effects.

Analgesia, Epidural↗
PubMed2001

The assessment of the proximal left pulmonary artery by transesophageal echocardiography and computed tomography in neonates and infants: a case series.

IMPLICATIONS: Transesophageal echocardiography (TEE) is often used during surgical repair of congenital heart disease. In our case series of 256 newborns and infants, we found that a left paracarinal view of TEE could visualize the proximal left pulmonary artery, a frequent blind spot for TEE, in most patients, except in a few cases with anatomic variations of the esophagus in the right lateral to the vertebra.

Cardiac Surgical Procedures↗
PubMed2001

[Substance P depresses GABA-activated currents in cultured hippocampal pyramidal neurons of rats].

The purpose of the present study was to explore whether substance P (SP) modulates the response mediated by GABAA receptors. Experiments were carried out on cultured hippocampal pyramidal neurons of rats. GABA-activated inward currents were recorded using the whole-cell-patch-clamp technique. The majority of the neurons examined (66/92, 72%) were sensitive to both GABA and SP. When the neurons were treated with SP prior to application of GABA, the GABA-activated current (IGABA) was inhibited markedly, which was concentration-dependent and could be blocked by spantide, an NK1 receptor antagonist. With 10(-8), 10(-7), 10(-6) and 10(-5) mol/L SP, IGABA was inhibited by 18%, 24.8%, 25.9% and 28% respectively. Intracellular application of H7, a potent inhibitor of PKC, abolished inhibition of IGABA by SP, suggesting that the inhibition of IGABA by SP may be a result of intracellular phosphorylation of the GABAA receptor.

Animals↗
PubMed2001

Bedside pericardiocentesis under the guidance of transesophageal echocardiography in a 13-month-old boy.

Pericardial effusion is a common sequel to cardiac surgery. Urgent pericardiocentesis is required in the case of cardiac tamponade. In adult patients, most pericardiocentesis is accomplished using transthoracic echocardiographic imaging. However, transthoracic echocardiographic imaging may interfere with the procedure field in children. We report the case of a 13-month-old boy who developed cardiac tamponade resulting in heart failure after surgical repair of tetralogy of Fallot. Urgent pericardiocentesis was safely performed at the bedside under transesophageal echocardiographic guidance. Transesophageal echocardiographic monitoring during pericardiocentesis in children has the advantages of better imaging of pericardial effusion without procedure-field interference.

Echocardiography, Transesophageal↗
PubMed2000

Telomere-binding and Stn1p-interacting activities are required for the essential function of Saccharomyces cerevisiae Cdc13p.

Yeast Saccharomyces cerevisiae Cdc13p is the telomere-binding protein that protects telomeres and regulates telomere length. It is documented that Cdc13p binds specifically to single-stranded TG(1-3) telomeric DNA sequences and interacts with Stn1p. To localize the region for single-stranded TG(1-3) DNA binding, Cdc13p mutants were constructed by deletion mutagenesis and assayed for their binding activity. Based on in vitro electrophoretic mobility shift assay, a 243-amino-acid fragment of Cdc13p (amino acids 451-693) was sufficient to bind single-stranded TG(1-3) with specificity similar to that of the native protein. Consistent with the in vitro observation, in vivo one-hybrid analysis also indicated that this region of Cdc13p was sufficient to localize itself to telomeres. However, the telomere-binding region of Cdc13p (amino acids 451-693) was not capable of complementing the growth defects of cdc13 mutants. Instead, a region comprising the Stn1p-interacting and telomere-binding region of Cdc13p (amino acids 252-924) complemented the growth defects of cdc13 mutants. These results suggest that binding to telomeres by Cdc13p is not sufficient to account for the cell viability, interaction with Stn1p is also required. Taken together, we have defined the telomere-binding domain of Cdc13p and showed that both binding to telomeres and Stn1p by Cdc13p are required to maintain cell growth.

Cyclin B↗
PubMed2000

Differential expression and regulation of macrophage inflammatory protein (MIP)-1alpha and MIP-2 genes by alveolar and peritoneal macrophages in LPS-hyporesponsive C3H/HeJ mice.

A point mutation in Toll-like receptor 4 (Tlr4) gene in C3H/HeJ mice underlies a defect in LPS-induced cytokine production by peritoneal macrophages (PMphi;). Whether the C-C and the C-X-C chemokines are induced differently by LPS between alveolar macrophages (AMphi;) and PMphi; in this mice remains unclear. Thus, we examined the expression and regulation of macrophage inflammatory protein-1alpha (MIP-1alpha) and macrophage inflammatory protein-2 (MIP-2) in C3H/HeJ macrophages. These results showed that the accumulation of MIP-1alpha and MIP-2 mRNA increased dose dependently in response to LPS. PMphi; responded to LPS to produce significantly higher levels of both chemokine mRNA and protein than AMphi;. In addition, both macrophages produced much more MIP-2 than MIP-1alpha by the same doses of LPS stimulation. Moreover, the chemokine production by C3H/HeN macrophages was significantly higher than that of the C3H/HeJ macrophages. IFN-gamma suppressed the LPS-induced MIP-1alpha release but enhanced the LPS-induced MIP-2 secretion in both macrophages. These results show that the chemokine production was induced and regulated differentially in AMphi; and PMphi;.

Animals↗
PubMed2000

Evaluating factors that influence hand-arm stress while operating an electric screwdriver.

The objective of this study is to evaluate the factors contributing toward hand-arm stress while operating an electric screwdriver. Hand-arm stress was investigated in terms of individual finger force exertion, flexor digitorum EMG, and hand-transmitted vibration. Two activation modes (push and push plus trigger (P + T)), two preset shut-off torque levels (low and high) and three horizontal operating distances (far, middle, and near) were evaluated. Thirteen healthy male subjects drove screws into a horizontally mounted iron plate with pre-tapped screw holes using an in-line electric screwdriver in randomly ordered experimental combinations. The results indicate that using push-to-start mode at low torque level was better than the other combinations of activation mode x torque because it resulted in less hand-arm stress. In addition, the far distance level (33-45 cm away from the work table edge) caused greater stress than the middle and near distances, and hence is best avoided. While operating an in-line electrical screwdriver, the force contribution of the small finger was greatest, followed by the ring finger. The average force contributions of the index, middle, ring, and small fingers were 19, 25, 27, and 30%, respectively, while operating with push-to-start mode.

Adult↗
PubMed2000

Prophylactic intravenous ondansetron reduces the incidence of intrathecal morphine-induced pruritus in patients undergoing cesarean delivery.

UNLABELLED: Pruritus is a common side effect of intrathecal morphine injection for postoperative pain control. Its incidence is especially high in patients undergoing cesarean delivery. We investigated the effectiveness of ondansetron in preventing intrathecal morphine-induced pruritus in such patients. We included 60 consecutive nonbreastfeeding women who were scheduled for elective cesarean delivery. After the administration of spinal anesthesia with bupivacaine and intrathecal morphine 0.15 mg injection, the patients were randomly divided into three groups. Group 1 received placebo (normal saline) IV injection, Group 2 diphenhydramine 30 mg IV injection, and Group 3 ondansetron 0.1 mg/kg IV injection. The incidence of pruritus was significantly lower in the ondansetron group (25%) when compared with that in the placebo group (85%) and in the diphenhydramine group (80%) (both P < 0.05). The postoperative pain score and time to flatus passage were not significantly different among the three groups. There were no headache or extrapyramidal signs associated with ondansetron use. In conclusion, ondansetron prophylaxis significantly reduced the incidence of intrathecal morphine-induced pruritus in patients undergoing cesarean delivery. IMPLICATIONS: Ondansetron prophylaxis significantly decreases the incidence of pruritus, a common side effect of intrathecal morphine used to treat postcesarean delivery pain.

Adolescent↗
PubMed2000

The effect of handle angle on MAWL, wrist posture, RPE, and heart rate.

In manual material handling tasks, the handle serves as the interface between the human operator and the box (the materials). Handle angle design can affect both wrist posture and lifting ability. This study was designed to evaluate the effect of handle angle on maximal acceptable weight of lifting (MAWL), perceived whole-body exertion, whole-body workload, wrist posture, and perceived wrist exertion. The results indicate that handle angle had a significant effect on wrist posture and wrist rating of perceived exertion (RPE). A box with a 0 degrees handle angle induced the greatest ulnar deviation and the highest wrist RPE. A 75 degrees handle angle induced the greatest radial deviation and a relatively high wrist RPE. A 30 degrees handle angle resulted in the greatest MAWL and the lowest level of wrist RPE. Overall, these findings suggest that 30 degrees and 45 degrees handle angles can provide favorable coupling conditions for the cutout-type handhold container handle. Actual or practical applications include the ergonomic design of container handles for manual material handling tasks industry.

Adult↗