Biomedical subjects

T Wu

Publications and source records attributed to T Wu.

At least 91 records · Page 5Linked to original sources

PubMed2000

Modification of the silent period by double transcranial magnetic stimulation.

OBJECTIVES: To study the time course of the changes of the inhibitory network of the human motor system, we investigated the silent period (SP) in 7 healthy subjects by double suprathreshold transcranial magnetic stimulation (TMS). METHODS: SPs and motor evoked potentials (MEPs) were recorded from the voluntarily activated right abductor digiti minimi muscle. Conditioning and test stimuli were delivered with equal intensity, which was set to yield a baseline SP duration of 130 ms by a single pulse, and with various interstimulus intervals (ISIs). In addition, a control experiment with adjustment of the intensity of single stimuli was performed. RESULTS: At ISIs of 20 and 30 ms the test pulse SP duration was prolonged, without increasing the MEP amplitude. The SP duration shortened at longer ISIs and showed a significant depression between ISIs of 60-110 ms. The shortened SP was accompanied by a diminished MEP. The control experiment revealed that the SPs evoked by the adjusted pulses were significantly shorter than the test pulse SPs. CONCLUSIONS: A conditioning stimulus can prolong and shorten the test pulse SP duration at different ISIs. The prolongation is probably cortically generated, whereas the shortening is likely to occur at a cortical and spinal level.

Adult↗

PubMed2000

Immunotherapy of a human papillomavirus (HPV) type 16 E7-expressing tumour by administration of fusion protein comprising Mycobacterium bovis bacille Calmette-Guérin (BCG) hsp65 and HPV16 E7.

Human papillomavirus type 16 (HPV16) infection has been linked to the development of cervical and anal dysplasia and cancer. One hallmark of persistent infection is the synthesis of the viral E7 protein in cervical epithelial cells. The expression of E7 in dysplastic and transformed cells and its recognition by the immune system as a foreign antigen make it an ideal target for immunotherapy. Utilizing the E7-expressing murine tumour cell line, TC-1, as a model of cervical carcinoma, an immunotherapy based on the administration of an adjuvant-free fusion protein comprising Mycobacterium bovis BCG heat shock protein (hsp)65 linked to HPV16 E7 (hspE7) has been developed. The data show that prophylactic immunization with hspE7 protects mice against challenge with TC-1 cells and that these tumour-free animals are also protected against re-challenge with TC-1 cells. In addition, therapeutic immunization with hspE7 induces regression of palpable tumours, confers protection against tumour re-challenge and is associated with long-term survival (> 253 days). In vitro analyses indicated that immunization with hspE7 leads to the induction of a Th1-like cell-mediated immune response based on the pattern of secreted cytokines and the presence of cytolytic activity following antigenic recall. In vivo studies using mice with targeted mutations in CD8 or MHC class II or depleted of CD8 or CD4 lymphocyte subsets demonstrate that tumour regression following therapeutic hspE7 immunization is CD8-dependent and CD4-independent. These studies extend previous observations on the induction of cytotoxic T lymphocytes by hsp fusion proteins and are consistent with the clinical application of hspE7 as an immunotherapy for human cervical and anal dysplasia and cancer.

Animals↗

PubMed2000

Studies of the drug permeability and mechanical properties of free films prepared by cellulose acetate pseudolatex coating system.

Free films produced with cellulose acetate (CA) pseudolatex were prepared by the casting method. The effects of plasticizer concentration, drying temperature, and drying time on drug permeability and mechanical properties of free films were investigated by three-factor spherical second-order composite experimental design. The results were analyzed by the multivariable regression method. The experimental results indicated that plasticizer concentration, drying temperature, and drying time had complex effects on free film permeability and mechanical behavior. These results probably arise from the film-forming ability of CA pseudolatex particles at various conditions and the evaporation of plasticizer during the film-forming process.

Algorithms↗

PubMed2000

Formulation optimization technique based on artificial neural network in salbutamol sulfate osmotic pump tablets.

The aim of this study was to develop a formulation optimization technique in which an artificial neural network (ANN) was incorporated; 30 kinds of salbutamol sulfate osmotic pump tablets were prepared, and their dissolution tests were performed. The amounts of hydroxypropyl methylcellulose (HPMC), polyethylene glycol 1500 (PEG1500) in the coating solution, and the coat weight were selected as the causal factors. Both the average drug release rate v for the first 8 hr and the correlation coefficient r of the accumulative amount of drug released and time were obtained as release parameters to characterize the release profiles. A set of release parameters and causal factors was used as training data for the ANN, and another set of data was used as test data. Both sets of data were fed into a computer to train the ANN. The training process of the ANN was completed until a satisfactory value of error function E for the test data was obtained. The optimal formulation produced by the technique gave the satisfactory release profile since the observed results coincided well with the predicted results. These findings demonstrate that an ANN is quite useful in the optimization of pharmaceutical formulations.

Albuterol↗

PubMed2000

Activin, inhibin, and follistatin in zebrafish ovary: expression and role in oocyte maturation.

Activins, inhibins, and follistatins are important regulators of mammalian reproduction. However, their roles in lower vertebrates are poorly understood. In this study, we examined the expression of activin A, inhibin A, and follistatins in the zebrafish ovary and determined their role in final oocyte maturation. Using reverse transcription-polymerase chain reaction with primers specific for activin/inhibin beta(A) subunit and for follistatins, we detected DNA fragments of the expected size, which, upon sequencing, conformed to activin/inhibin beta(A) and follistatin. Western blot analysis using an antibody against activin/inhibin beta(A) subunit revealed two bands with sizes similar to those of activin A and inhibin A. The expression of follistatins was also confirmed by Western blot analysis. These results suggest that activin A, an inhibin A-like molecule, and follistatins are expressed in the zebrafish ovary. In cultured zebrafish follicles, activin A and inhibin A both induced final oocyte maturation in a dose-dependent manner. The effects of activin A and inhibin A were blocked by their binding protein, follistatin-288. Interestingly, follistatin-288 also inhibited final oocyte maturation induced by gonadotropin and by maturation-inducing hormone (MIH), suggesting that activin A and/or inhibin A may be local regulators mediating gonadotropin- and MIH-induced final oocyte maturation. Taken together, these findings suggest that activin A and inhibin A are paracrine regulators of ovarian functions in fish.

Activins↗

PubMed2000

Evaluation of the physician's ability to recognize the presence or absence of anemia, fever, and jaundice.

OBJECTIVE: The evaluation of the patient through a comprehensive history and physical examination is considered the cornerstone of medical diagnosis, but many studies suggest that physicians have inadequate physical examination skills. It is unknown whether these skills are reliable and whether they can be adequately acquired through training. The objective of this study was to evaluate the ability of the clinician to detect the presence and discriminate the extent of clinical anemia, fever, and jaundice in an ED or hospitalized patient. METHODS: This was a prospective observational study of a convenience sample of patients presenting to the ED or admitted to the hospital who had a rectal temperature measurement within 30 minutes prior to the observation, serum hematocrit measurement on the day of observation, or serum bilirubin measurement one day prior to the day of observation. Observers' (emergency medicine attending physicians', resident physicians', and rotating medical students') estimated serum hematocrit, rectal temperature, and serum bilirubin values were obtained after each observation. Sensitivity, specificity, positive predictive value, negative predictive value, and mean absolute difference between actual and estimated values were calculated for each observer. RESULTS: The physicians detected the presence or absence of anemia, fever, and jaundice in patients with sensitivities and specificities of approximately 70%. Their predictions varied from the measured value on average by 6.0 +/- 4.6% for serum hematocrit, 1.3 + 1.1 degrees F for rectal temperature, and 3.4 +/- 5.3 mg/dL for serum bilirubin. Observer accuracy decreased when evaluating patients with high and low measured values. CONCLUSIONS: The ability to correctly perform and interpret the physical examination appears to be independent of the observer level of training, patient ethnicity, or patient gender. The examination for pallor, warmth, and jaundice is unreliable in predicting the corresponding laboratory or electronic measurement. Certain anemic, febrile, or jaundiced patients may not be reliably detected solely by a focused physical examination.

Adolescent↗

PubMed2000

Reliability of water proton chemical shift temperature calibration for focused ultrasound ablation therapy.

Our purpose in this work was to assess the reliability of the calibration coefficient for magnetic resonance water proton chemical shift temperature mapping. Over a six month period, the calibration coefficient was measured 15 times in several different phantoms. A highly linear relationship between water proton chemical shift and temperature change was found. The average temperature calibration coefficient determined from all studies was 0.009+/-0.001 ppm/degrees C. Four of the 15 studies were conducted on the same day using the same phantom. The average temperature calibration coefficient of these four studies was 0.0096+/-0.0001 ppm/degrees C.

Biophysical Phenomena↗

PubMed2000

From a profiled diffuser to an optimized absorber

The quadratic residue diffuser was originally designed for enhanced scattering. Subsequently, however, it has been found that these diffusers can also be designed to produce exceptional absorption. This paper looks into the absorption mechanism of the one-dimensional quadratic residue diffuser. A theory for enhanced absorption is presented. Corresponding experiments have also been done to verify the theory. The usefulness of a resistive layer at the well openings has been verified. A numerical optimization was performed to obtain a better depth sequence. The results clearly show that by arranging the depths of the wells properly in one period, the absorption is considerably better than that of a quadratic residue diffuser.

Journal Article↗

PubMed2000

Enhanced extracellular production of aspartyl proteinase, a virulence factor, by Candida albicans isolates following growth in subinhibitory concentrations of fluconazole.

We examined the production of secreted aspartyl proteinase (Sap), a putative virulence factor of Candida albicans, by a series of 17 isolates representing a single strain obtained from the oral cavity of an AIDS patient before and after the development of clinical and in vitro resistance to fluconazole. Isolates were grown in Sap-inducing yeast carbon base-bovine serum albumin medium containing 0, 0.25, 0.5, or 1 MIC of fluconazole, and cultures were sampled daily for 14 days to determine extracellular Sap activity by enzymatic degradation of bovine serum albumin. Extracellular Sap activity was significantly decreased in a dose-dependent manner for the most fluconazole-susceptible isolate (MIC, 1.0 microg/ml) and significantly increased in a dose-dependent manner for the most fluconazole-resistant isolate (MIC, >64 microg/ml). Enhanced extracellular Sap production could not be attributed to cell death or nonspecific release of Sap, because there was no reduction in the number of CFU and no significant release of enolase, a constitutive enzyme of the glycolytic pathway. Conversely, intracellular Sap concentrations were significantly increased in a dose-dependent manner in the most fluconazole-susceptible isolate and decreased in the most fluconazole-resistant isolate. Enhanced Sap production correlated with the overexpression of a gene encoding a multidrug resistance (MDR1) efflux pump occurring in these isolates. These data indicate that exposure to subinhibitory concentrations of fluconazole can result in enhanced extracellular production of Sap by isolates with the capacity to overexpress MDR1 and imply that patients infected with these isolates and subsequently treated with suboptimal doses of fluconazole may experience enhanced C. albicans virulence in vivo.

Animals↗

PubMed2000

Zinc finger structures in the human immunodeficiency virus type 1 nucleocapsid protein facilitate efficient minus- and plus-strand transfer.

The nucleocapsid protein (NC) of human immunodeficiency virus type 1 (HIV-1) has two zinc fingers, each containing the invariant metal ion binding residues CCHC. Recent reports indicate that mutations in the CCHC motifs are deleterious for reverse transcription in vivo. To identify reverse transcriptase (RT) reactions affected by such changes, we have probed zinc finger functions in NC-dependent RT-catalyzed HIV-1 minus- and plus-strand transfer model systems. Our approach was to examine the activities of wild-type NC and a mutant in which all six cysteine residues were replaced by serine (SSHS NC); this mutation severely disrupts zinc coordination. We find that the zinc fingers contribute to the role of NC in complete tRNA primer removal from minus-strand DNA during plus-strand transfer. Annealing of the primer binding site sequences in plus-strand strong-stop DNA [(+) SSDNA] to its complement in minus-strand acceptor DNA is not dependent on NC zinc fingers. In contrast, the rate of annealing of the complementary R regions in (-) SSDNA and 3' viral RNA during minus-strand transfer is approximately eightfold lower when SSHS NC is used in place of wild-type NC. Moreover, unlike wild-type NC, SSHS NC has only a small stimulatory effect on minus-strand transfer and is essentially unable to block TAR-induced self-priming from (-) SSDNA. Our results strongly suggest that NC zinc finger structures are needed to unfold highly structured RNA and DNA strand transfer intermediates. Thus, it appears that in these cases, zinc finger interactions are important components of NC nucleic acid chaperone activity.

Genome, Viral↗

PubMed2000

Optimization strategies for DNA vaccines.

DNA immunization is a relatively new vaccination strategy that involves the direct introduction into the host of plasmid DNA encoding the desired antigen. The DNA enters host cells and results in immune responses following in vivo expression of the antigen. Although DNA-based immunization works well in animal models for the induction of both humoral and cell-mediated immune responses, its success in humans has been limited. This paper discusses different approaches that have attempted to optimize DNA vaccines, and presents results evaluating some of these approaches in mice.

Adjuvants, Immunologic↗

PubMed2000

New potential photodynamic therapeutic anti-cancer agents: synthesis and characterization of demethoxy amino-substituted hypocrellins.

A novel method was used to obtain demethoxy amino-substituted hypocrellin derivatives. The reaction condition was mild and amino substitution occurred at position 2 or 11 of hypocrellins with high yield. The photophysical and photochemical properties of the amino-substituted hypocrellins derivatives were investigated, and their significantly enhanced red absorptivities and strong active oxygen-generating functions qualified them as promising photodynamic therapeutic anti-cancer agents.

Antineoplastic Agents↗

PubMed2000

Dimethylamiloride-induced differentiation of HL-60 cells.

AIM: To study the effect of 5-(N,N-dimethyl) amiloride (DMA) on the proliferation and differentiation of HL-60 cells in vitro. METHODS: MTT assay to test cytotoxicity; cell staining and NBT reduction to test cell differentiation. RESULTS: DMA inhibited HL-60 cells growth in a concentration-dependent manner, and IC50 value for 96 h was 31.7 (95% confidence limits: 6.3-57.1) mumol.L-1. DMA also induced granulocytic differentiation in HL-60 cells. The percentage of differentiating cells increased from 6.5% to 70% after DMA 100 mumol.L-1 treatment for 3 d. The differentiating effect of DMA was distinguishable from amiloride, 5-(N-ethyl-N-isopropyl)amiloride (EIPA), and (5-(N-ethyl-N-isopropyl)amiloride (MIA). None among the amiloride, EIPA, and MIA were capable of triggering the differentiation of HL-60 cells. CONCLUSION: DMA inhibited the proliferation of HL-60 cells and induced differentiation of HL-60 cells.

Amiloride↗

PubMed2000

[Transdermal delivery mechanisms of lecithin nanoparticles with cyclosporin A through mice skin].

AIM: To investigate the transdermal delivery mechanisms of the flexible nano-liposomes, conventional nano-liposomes and lecithin-cholate mixed micelles through mouse skin. METHODS: Liposomes and micelles were applied onto the mouse skin non-occlusively in vitro and in vivo, then the drug concentrations in the skin, receiver and blood were determined. RESULTS: In vitro permeation studies showed that flexible nano-liposomes and mixed micelles transported measurable amount of cyclosporin A through the skin. Conventional liposomes precluded drugs permeate through the skin while deposited it in the skin. In vivo studies indicated that blood concentration reached peak value at 8 h after the application of flexible nano-liposomes. Both conventional nano-liposomes and mixed micelles failed to deliver measurable amount of drug into the blood. CONCLUSION: Liposomes fuse with the skin. Flexible nano-liposomes penetrate through the skin under the pressure of hydration force. Mixed micelles promote transfer in state of solution.

Administration, Cutaneous↗

PubMed2000

[Community -based comprehensive prevention and control of hypertension in China (CCPACH Study)-prevalence and epidemiological characteristics in urban and rural area].

OBJECTIVE: To understand the epidemiological features and prevalence of essential hypertension in the rural communities. METHODS: A community-based survey on essential hypertension was carried out in urban and rural areas involving 280,000 population. RESULTS: The prevalence rate of hypertension in age 35 years and over was 31.7% and 32.9% in urban and rural respectively; the average age of the patients' in urbans was significantly higher than in rural areas. Among non-hypertensive cases, more than 50% of the population having risk factors of hypertension in both urban and rural areas. Rates of treatment and control awareness of hypertension were 56.3%, 26.8% and 4.4% respectively in urban; comparing to 40.3%, 17.5% and 2.6% respectively, in the rural areas. More than half of the diagnosed patients before survey did not take antihypertensive medicine for treatment in both areas. The proportions the classification of hypertension were similar in both areas with majority of them, mild and isolated systolic hypertension. CONCLUSIONS: It was demonstrated that there is an urgent need to carry out comprehensive prevention and control for hypertension in urban and rural area.

Adult↗

PubMed2000

[The epidemiological characteristics of multiple metabolic disorders in hypertensive patients in the communities].

OBJECTIVES: To describe the epidemiological characteristics of multiple metabolic disorders on hypertensive patients living in the communities. METHODS: The characteristics of metabolic disorders in the hypertensives from one community in Shanghai urban area were analyzed. Metabolic disorders would include dyslipidemia (high cholesterol and/or high triglycerides and/or low HDL cholesterol), diabetes and obesity. RESULTS: 59.2% of the hypertensives at least had one metabolic disorder. Proportionally, 83.9%, 15.5%, 0.6% of the patients would combine one, two, or all of the disorders. The percentages of patients combined with dyslipidemia, diabetes and obesity were 53.0%, 9.7%, 6.3%, respectively. 74.0% of patients with metabolic disorders were combined with dyslipidemia while 9.1% were combined with both dyslipidemia and diabetes. The standardized prevalence rate of male patients with metabolic disorders was 58.1%, higher than the rate of women (54.5%). The prevalence rate of postmenopausal female patients with metabolic disorders was 67.6%, significantly higher than that of the premenopausal women (44.4%) (chi(2) = 37.49, P < 0.01). CONCLUSION: Nearly 60% of the total patients combined with metabolic disorders. Dyslipidemia occurred in more than half of the patients in total. The proportion of senile patients with metabolic disorders was higher than the younger patients. Results suggested that attempts to maintain the coronary heart disease at low levels in the population should include treatment of dyslipidemia to keep lipid and diabetes prevalence at low levels other than regular antihypertensive therapy.

Adult↗

PubMed2000

[Evaluation on the effects of community-based comprehensive prevention and control of hypertension in the rural areas in China].

OBJECTIVE: To explore the strategies and measures of community-based comprehensive prevention and control of hypertension in the rural areas. METHODS: Community-based comprehensive prevention and control of hypertension was put in practice in 120,000 people in Fangshan District of Beijing during the period of "The Ninth Five-Year Plan (1996 - 2000)". RESULTS: After intervention, blood pressure of the whole subjects were under control and kept the level of baseline data; the rate of increase of prevalence in the intervention areas was below the rate of that from 1979 to 1991 in China (the former was 14.7%, while the latter was 53.7%); the incidence rate of the subjects was 1.4%, close to the average rate of age 15 and above in China; the rates of awareness, treatment and control were above the levels of baseline data; SBP and DBP of the patients decreased by 2.9% and 5.6%, respectively; while the rate of having high risk factors reduced by 13.4% on average. CONCLUSION: The community-based comprehensive strategies and measures played an important and effective role in prevention and control of hypertension in rural areas.

Adult↗

PubMed2000

[Evaluation on the effect of Benazepril for hypertension through postmarketing surveillance].

OBJECTIVE: To evaluate the efficacy and safety of Benazepril used among the essential hypertensives. METHODS: 1 831 essential hypertensive patients aged 35 to 75 were randomly selected from a community and followed for 18 months. The level of blood pressure, status of taking Benazepril and side effects were sequencially collected. RESULTS: 1/3 of the patients had taken antihypertensive drug before the study and the rate of compliance was over 96%. The effective rate of Benazepril was 73.6% at three months and increased to 84.7% at 18 months. Comparing with the baseline data, SBP and DBP declined 10.8 mmHg and 6.7 mmHg respectively. The rate of side effect was 22.7%. Cough was most commonly seen among side effects. The peak of first recording on side effect occurred at three months including 60% of them mild. CONCLUSION: Results showed that Benazepril had good efficacy and safety for the essential hypertension patients in a long-term observation.

Adult↗