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Biomedical subjects

L Y Huang

Publications and source records attributed to L Y Huang.

At least 19 recordsLinked to original sources
PubMed2001

Alteration in the voltage dependence of NMDA receptor channels in rat dorsal horn neurones following peripheral inflammation.

1. It has been proposed that the activation of NMDA receptors and upregulation of protein kinase C (PKC) underlie the exaggerated and persistent pain experienced in the inflammatory state. However, there is no direct evidence to show that inflammation alters the function of NMDA receptors. 2. We examined the voltage-dependent properties of NMDA receptor channels in rat dorsal horn neurones that receive sensory inputs from an inflamed hindpaw. 3. Peripheral inflammation was induced by injections of complete Freund's adjuvant (CFA). Membrane currents were measured using the perforated patch-clamp technique. 4. After CFA treatment, the current-voltage relationship of NMDA receptor channels was shifted in the hyperpolarized direction. This resulted in enhanced NMDA responses at negative potentials. 5. The change was mediated by PKC because the voltage shift was blocked by the selective PKC inhibitors chelerythrine and bisindolylmaleimide I. 6. Furthermore, the Mg(2+) blockade of NMDA receptors was reduced. This reduction could account for the shift in the voltage dependence of NMDA receptor channels. 7. These results indicate that NMDA receptor channel characteristics in the dorsal horn are altered by inflammation, and that the changes observed could contribute to the hyperalgesia and allodynia associated with tissue injury.

Animals↗
PubMed2001

IL-12 induction by a TH1-inducing adjuvant in vivo: dendritic cell subsets and regulation by IL-10.

IL-12 induction is critical for immune responses against many viruses and intracellular bacterial pathogens. Recent studies suggest that IL-12-secreting dendritic cells (DC) are potent Th1-inducing APC. However, controversy exists concerning the function of DC subsets. Murine studies have suggested that CD8(+) DC preferentially induce Th1 responses, whereas CD8(-) DC induce Th2 development; in this model, different DC subsets prime different responses. Alternatively, the propensity of DC subsets to prime a Th1 response could depend upon the type of initial stimulus. We used a prototypic Th1-inducing adjuvant, heat-killed Brucella abortus (HKBA) to assess stimulation of DC subsets, relationship between Ag burden and IL-12 production, and down-regulation of DC subset IL-12 production by IL-10. In this study, we show that DC were sole producers of IL-12, although most HKBA uptake was by splenic macrophages and granulocytes. More CD8(-) than CD8(+) DC produced IL-12 after HKBA challenge, whereas only CD8(+) DC produced IL-12 after injection of another Th1-promoting microbial substance, soluble Toxoplasma gondii Ags. Studies in IL-10-deficient mice revealed that IL-10 down-regulates frequency and duration of IL-12 production by both DC subsets. In the absence of IL-10, IL-12 expression is enabled in CD11c(low) cells, but not in macrophages or granulocytes. These findings support the concept of DC as the major IL-12 producers in spleens, but challenge the notion that CD8(+) and CD8(-) DC are destined to selectively induce Th1 or Th2 responses, respectively. Thus, the nature of the stimulating substance is important in determining which DC subsets are activated to produce IL-12.

Adjuvants, Immunologic↗
PubMed2001

High prevalence of TT virus-related DNA (90%) and diverse viral genotypes in Norwegian blood donors.

Early estimates of the prevalence of TTV viremia in healthy adults of developed countries were in the order of 1--10 %, while similar estimates in Third World countries were considerably higher. Using three different PCRs, TTV-related DNA was detected in serum from 180 out of the 201 Norwegian blood donors tested, indicating that these viruses are almost universally present in adults. Sequence analysis revealed heterogeneity similar to what is found world-wide. The data suggest that the previous discrepancy in prevalences might be related to a lower serum concentration of virus in developed countries. The high prevalence adds evidence to the benign nature of the virus.

Adolescent↗
PubMed2001

Immunity and protection against Brucella abortus.

Brucella abortus is an intracellular pathogen that causes disease in cattle and in humans. The response against B. abortus involves the whole gamut of the immune system, from innate to adaptive immunity resulting from stimulation of antigen-presenting cells, NK cells, CD4(+) and CD8(+) T cells, and B cells.

Animals↗
PubMed2001

[Studies on bioconversion conditions and stereoselectivity of Arthrobacter K1108 hydantoinase].

The bioconversion conditions of hydantoinase of Arthrobacter K1108 were studied. It was shown that the optimum temperature of the enzyme is 55 degrees C, and the optimum pH is 7.0. The enzyme can be activated by Co2+ and Fe2+, while inhibited by Ca2+. The optimal substrate of the hydantoinase is 5-benzylhydantoin, while 5-phenylhydantoin and 5-indolylmethylhydantoin cannot effectively digested, showing a high specificity on the substrates. An investigation on the hydantoinase stereoselectivity mechanism showed that the N-carbamoylamino acid hydrolase is stereoselective but the hydantoin hydrolase is not.

Amidohydrolases↗
PubMed2001

[The design of a practical instant ECG pocket recorder].

The Holter is no doubt very useful in clinic to help doctor to capture and understand the seizure from the ECG. But the device is not convenient to be use at home and is still very expensive now. This paper introduces a practical instant ECG recorder which a patient can take with at any time. It's cheap and easy of use.

Electrocardiography, Ambulatory↗
PubMed2000

Activation of silent mechanoreceptive cat C and Adelta sensory neurons and their substance P expression following peripheral inflammation.

The effect of inflammation on the excitability and the level of substance P (SP) in cat mechanoreceptive C and Adelta dorsal root ganglion (DRG) neurons were studied in vivo using intracellular recording and immunocytochemical techniques. Following injections of carrageenan (Carg) into the cat hindpaw, the percentage of C neurons exhibiting spontaneous activity increased from 7.2 to 20.7% and the percentage of Adelta neurons increased from 6.9 to 18.6%. In contrast to most cells from normal cats, which fired regularly below 10 Hz, many cells from Carg-treated cats fired at higher frequencies or in bursts. Inflammation (Carg treatment) also depolarized membrane potentials, increased membrane input resistance, caused the disappearance of inward rectifying currents and lowered the mean current thresholds of tibial nerve-evoked responses in DRG neurons. With inflammation, the percentage of C or Adelta neurons responding to low threshold mechanoreceptive stimuli increased (C neurons: normal, 13%; inflamed, 41%; Adelta neurons: normal, 13 %; inflamed, 39 %), while the percentage of C or Adelta neurons responding to high threshold mechanoreceptive stimuli remained unchanged. Some receptive field (RF)-responsive cells were injected with Lucifer Yellow and their SP immunoreactivity was determined. Following Carg treatment, substantially higher percentages of RF-responsive cells were SP positive (C neurons: normal, 35.7%; inflamed, 60%; Adelta neurons: normal, 18.2%; inflamed, 66.7%). These combined increases in the excitability of DRG neurons and SP-containing RF-responsive neurons could lead to sensitization of sensory neurons, thus contributing to the development of hyperalgesia.

Animals↗
PubMed2000

Anterolateral thigh vastus lateralis myocutaneous flap for vulvar reconstruction after radical vulvectomy: a preliminary experience.

BACKGROUND: There are many myocutaneous flap methods which have been reported for the immediate reconstruction of large vulvar defects created by deforming radical cancer surgery in the female perineum except for the anterolateral thigh vastus lateralis myocutaneous flap. The present report describes our preliminary experience with the use of this flap in a patient who underwent radical vulvectomy for locally advanced squamous cell carcinoma of the vulva. CASE: A 75-year-old woman underwent radical vulvectomy with bilateral inguinal lymphadenectomy due to right vulvar squamous cell carcinoma. The large vulvar defect was immediately reconstructed by using anterolateral thigh vastus lateralis myocutaneous flap. The postoperative course was uneventful. In addition to the expected primary healing, the neovulva had a relatively normal appearance with satisfactory sensation and function and the donor defect was found to be minimal both functionally and aesthetically. CONCLUSION: This technique can be used as an alternative method for vulvar reconstruction after radical vulvectomy. Further studies are warranted to prove the efficacy of this myocutaneous flap in reconstructing large vulvar defects.

Aged↗
PubMed2000

A study of the process and kinetics of electrochemical deposition and the hydrothermal synthesis of hydroxyapatite coatings.

Hydroxyapatite (HAp) coatings were prepared using electrochemical deposition and post-hydrothermal synthesis. The composition and morphology of coatings at each processing step was studied through the application of scanning electron microscopy (SEM), X-ray diffraction (XRD) and infra-red spectroscopy (IR). The mechanism and kinetics of hydrothermal synthesis were considered in particular, and the influence of the temperature and time on the HAp formation rate was also investigated. The results show that the electrochemical deposition coatings are composed of CaHPO42H2O crystals which are converted into needle-like HAp crystals after post-hydrothermal treatment. The HAp content of the coatings increases with the treatment temperature and time. The synthesis rate also increases with the pH value of the water. The formation of HAp coatings is considered to be a combination of several reactions. An Arrhenius relationship was found between the HAp formation rate and the temperature, and an apparent activation energy of 94.4 KJ/mol was obtained by calculation.

Journal Article↗
PubMed2000

Effects of four methods of sperm preparation on motion characteristics and nitric oxide concentration in laboratory-prepared oligospermia.

BACKGROUND: To compare four different spermatozoa preparation methods in semen samples with respect to recovery rate, percent motility, path and progressive velocity, and nitric oxide (NO) production before and after centrifugation. METHODS: Each of 36 semen specimens was diluted to 1 x 10(6)/ml and divided into four 1-ml aliquots for sperm processing using four methods: swim-up, two (Percoll II) and three (Percoll III) layer Percoll (Pharmacia Biotech AB, Uppsala, Sweden) gradients and albumin columns. The motile sperm recovery rate, percent motility and motion parameters were measured for each semen specimen (n = 36) before and after processing using the four methods. NO was measured with the use of a chemiluminescence method before and after centrifugation (n = 17). RESULTS: The sperm recovery rate was higher using both Percoll gradients than with the other two methods (Percoll II, 68 +/- 20.5%, Percoll III, 75.3 +/- 22.2% vs swim-up, 25.8 +/- 9.9% and albumin, 33.1 +/- 20.7%). The results were similar for total motile cells (Percoll II, 3.55 +/- 1.72 x 10(6)/ml, Percoll III, 4.25 +/- 1.29 x 10(6)/ml vs swim-up, 1.19 +/- 0.71 x 10(6)/ml and albumin, 1.89 +/- 1.36 x 10(6)/ml). Both Percoll methods and the albumin method produced a statistically significant improvement over the swim-up method in motility. The albumin column method resulted in the least path and progressive velocities (51.3 +/- 15.4 microns/s and 46.2 +/- 16.5 microns/s, respectively). NO produced during sperm processing did not differ significantly among the four processing methods (swim-up, 4,531 +/- 1,626 nM, Percoll II, 5,119 +/- 3,969 nM, Percoll III, 6,060 +/- 5,512 nM, albumin 4,838 +/- 2,462 nM). CONCLUSIONS: Our data suggest that Percoll methods are superior to swim-up and albumin columns for sperm preparation, yielding good sperm recovery, motility and motion characteristics. The trend toward lower NO levels among samples prepared using albumin columns did not reach statistical significance.

Cell Separation↗
PubMed1999

Mechanism underlying increased neuronal activity in the rat ventrolateral periaqueductal grey by a mu-opioid.

1. The overall effect of the mu-opioid receptor agonist DAMGO (Tyr-D-Ala-Gly-MePhe-Gly-ol) on ventrolateral periaqueductal grey (PAG) neurons in brain slices was studied using the whole-cell patch-clamp recording technique. 2. Under current-clamp conditions, DAMGO (1 microM) increased cell firing in many PAG neurons even though the opioid induced hyperpolarization and inhibited excitatory postsynaptic potentials (EPSPs) in these cells. 3. The increase in cell activity by DAMGO was observed in both transverse and horizontal slices. The increase persisted when the membrane potential was re-depolarized to the control level. Thus, different planes of sections or the removal of Na+ channel inactivation could not account for the observation. 4. The GABA antagonist bicuculline caused cell firing, mimicking the excitatory effect of DAMGO. Unlike DAMGO, however, bicuculline depolarized PAG cells. 5. Under voltage-clamp conditions, with the same driving force, the evoked inhibitory postsynaptic currents (IPSCs) in these neurons were 2.3 times larger than the evoked excitatory postsynaptic currents (EPSCs). Furthermore, DAMGO inhibited IPSCs by 60.7% while it inhibited EPSCs by 35.3%. 6. We propose that the overall effect of an opioid depends on the dynamic balance of its excitatory and inhibitory actions. In the PAG, the blockade of the inhibitory drive of GABAergic inputs by DAMGO is large. It overcomes the DAMGO-induced hyperpolarization and inhibition of EPSCs and thus results in the excitation of these neurons.

Analgesics, Opioid↗
PubMed1999

Non-metastatic Ewing's sarcoma: twenty years of experience suggests that surgery is a prime factor for successful multimodality therapy.

Eighty-five patients (37 female, 48 male; median age 14 years) with non-metastatic Ewing's sarcoma received definitive treatment at the University of Texas M.D. Anderson Cancer Center between 1969 and 1988. Multidisciplinary therapy was administered as follows: combination chemotherapy (CC) and local radiotherapy (XRT): 65 patients; CC, XRT and surgery, 19 patients; and XRT and surgery, 1 patient. This permitted a 10-20 year follow-up for 75% of our patients. The overall survival at 5 and 10-20 years was 46.1%, and 37.2%, respectively. At 5 years, 80.5% of live patients had control of local disease. The influence of sex, age, ethnicity, primary site, size, lactic dehydrogenase (LDH) level, presence or absence of systemic symptoms, and XRT dose (<60 Gy and </=60 Gy) was analyzed and was not found to be of prognostic significance in survival. The presence of a soft tissue mass at diagnosis was found to be a significant unfavorable prognostic variable. Nine of 11 patient who underwent resection after CC and/or XRT had residual tumor in the surgical specimen. Patients who received surgery as part of the planned treatment of their primary tumor had significantly better local control and disease-free survival than those who did not undergo resection. Complications in long-term survivors are described.

Adolescent↗
PubMed1999

The impact of department sub-division on hospital performance.

BACKGROUND: Chang Gung Memorial Hospital is the first hospital in Taiwan to adopt the 'sub-division management'. The hospital sub-divided extensively growing departments into two or more similar sub-divisions. This study compared the relative performance before and after the implementation of "sub-division management". METHODS: The cardiac department of Chang Gung Memorial Hospital was subdivided into Cardiac I and Cardiac II in July 1992. This study collected the managerial information of cardiac inpatients from 1991 through 1993 in Chang Gung Memorial Hospital. By exploring the effects of the "sub-division management" and other confounding factors, we tried to find out the possible impact they brought to hospital performance. RESULTS: Considering a time trend effect, the results of regression indicate that 'sub-division' mechanism had little effect on departmental performance. However, the performance is different between Cardiac I and Cardiac II in the aspect of total expenditure per admission, average length of stay, and average number of discharge per physician. These differences might be affected by the characteristics of physicians' sub-specialties rather than the implementation of sub-division management. CONCLUSION: The significant decrease in mortality rate of patients in the cardiology department after the implementation might suggest that the quality of care in the cardiology department increased after the introduction of sub-divisions. The long-term effects of practice behavior induced by competition within and between sub-divisions require further organizational and behavioral studies.

Efficiency↗
PubMed1998

GABA(B) receptors function as a heteromeric assembly of the subunits GABA(B)R1 and GABA(B)R2.

The principal inhibitory neurotransmitter GABA (gamma-aminobutyric acid) exerts its effects through two ligand-gated channels, GABA(A) and GABA(C) receptors, and a third receptor, GABA(B) , which acts through G proteins to regulate potassium and calcium channels. Cells heterologously expressing the cloned DNA encoding the GABA(B)R1 protein exhibit high-affinity antagonist-binding sites, but they produce little of the functional activity expected from studies of endogenous GABA(B) receptors in the brain. Here we describe a new member of the GABA(B) polypeptide family, GABA(B)R2, that shows sequence homology to GABA(B)R1. Neither GABA(B)R1 nor GABA(B)R2, when expressed individually, activates GIRK-type potassium channels; however, the combination of GABA(B)R1 and GABA(B)R2 confers robust stimulation of channel activity. Both genes are co-expressed in individual neurons, and both proteins co-localize in transfected cells. Moreover, immunoprecipitation experiments indicate that the two polypeptides associate with each other, probably as heterodimers. Several G-protein-coupled receptors (GPCRs) exist as high-molecular-weight species, consistent with the formation of dimers by these receptors, but the relevance of these species for the functioning of GPCRs has not been established. We have now shown that co-expression of two GPCR structures, GABA(B)R1 and GABA(B)R2, belonging to the same subfamily is essential for signal transduction by GABA(B) receptors.

Amino Acid Sequence↗
PubMed1998

HIV peptide conjugated to heat-killed bacteria promotes antiviral responses in immunodeficient mice.

Enhancement of immunity in the setting of HIV infection is difficult owing to loss of functional CD4+ T cells. The MHC class II-deficient mouse (II-/-) environment simulates that of the immunocompromised HIV-infected individual, since these mice have low CD4+ T cell numbers, defective CD4-dependent responses, and are susceptible to opportunistic infection. This strain was used to test whether heat-killed Brucella abortus (BA), covalently conjugated to the V3 peptide of HIV-1 (MN), could elicit anti-HIV responses. V3-BA, but not the T-dependent antigen V3-KLH, induced high levels of IL-12, IFN-gamma, and IL-10 mRNA in both wild-type (WT) and II-/- mice within 24 hr of injection. V3-BA-treated, but not V3-KLH-treated, II-/- mice developed serum IgG and IgA anti-V3 antibodies, with IgG2b and IgG3 as the predominant isotype. Viral neutralization studies, using a syncytium inhibition assay, demonstrated that the antibodies generated by V3-BA in II-/- mice were capable of neutralizing HIV. These experiments demonstrate that a heat-inactivated bacterium such as BA, when used as a carrier, can generate a cytokine environment that results in the production of neutralizing antiviral antibodies in an immunodeficient host. Such strategies could be important in the development of immunotherapies and vaccines for HIV-1 patients.

AIDS Vaccines↗
PubMed1998

Dynorphin uses a non-opioid mechanism to potentiate N-methyl-D-aspartate currents in single rat periaqueductal gray neurons.

The interaction of the endogenous K-opioid, dynorphin, with N-methyl-D-aspartate (NMDA) receptors was studied in single periaqueductal gray (PAG) cells using the whole cell patch recording technique. We have found that dynorphin A (1-17) rapidly and reversibly potentiates NMDA-activated currents in a subpopulation of PAG cells. The potentiation cannot be blocked by the non-specific opioid antagonist, naloxone, nor can it be reversed by the specific kappa-opioid antagonist, nor-BNI. In addition, the non-opioid fragment of dynorphin, dynorphin A (2-17), is effective in potentiating NMDA currents, while the specific kappa-opioid, U50,488, cannot mimic the action of dynorphin A (1-17). The non-opioid dynorphin action and the rapid onset and recovery of the potentiation are consistent with the idea that dynorphin interacts directly with NMDA receptors in PAG cells.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1998

Cross-modulation of glycine-activated Cl- channels by protein kinase C and cAMP-dependent protein kinase in the rat.

1. The cross-modulation of glycine responses by cyclic-AMP-dependent protein kinase (PKA) and protein kinase C (PKC) was determined in acutely dissociated trigeminal neurons. 2. Whole-cell glycine-evoked Cl- current (IGly) was recorded using the patch clamp technique. Protein kinases and their inhibitors were intracellularly perfused into the cells. 3. Both PKA and PKC when applied separately potentiated IGly. 4. When PKA and PKC were sequentially applied, PKC could not increase the IGly any further after the glycine responses were enhanced by PKA. 5. In 42% of our cells, IGly increased spontaneously. Endogenous PKA was found to mediate the increase. PKC had no effects on IGly in these cells. 6. The effect of PKA on IGly was studied in PKC-pretreated cells. PKA failed to potentiate IGly in these cells, suggesting that the PKA action also depends on the activity of PKC inside the cells. 7. These results suggest that the PKC action on IGly is conditional upon the modulation of the currents by PKA and vice versa. This cross-regulation of ligand-gated channel activity by protein kinases may play a role in neuronal integration and synaptic plasticity.

Action Potentials↗