Biomedical subjects

W Li

Publications and source records attributed to W Li.

At least 1,441 records · Page 80Linked to original sources

PubMedDate not supplied

Use of alternative therapy among pediatric oncology patients in Taiwan.

Both alternative medicine and western medicine have been commonly used to treat pediatric cancer patients in Taiwan. Each has its own intrinsic strengths and weaknesses and they can be complementary. Little is known about medical help-seeking behaviors of parents of pediatric cancer patients, especially those related to alternative therapies. This study investigated the extent and parental expectations on use of alternative therapies. All primary caregivers of 63 eligible patients were interviewed. Use of alternative therapies, regardless of education level or social status of their families, is prevalent (n = 46, 73%) in Taiwan. Commonly used alternative therapies included, in order of popularity, formulated functional food (n = 22, 48%), temple worship/shamanism (n = 19, 40%), traditional Chinese medicine (n = 9, 20%), secret recipes/herbs (n = 13, 28%), and diet supplements (n = 9, 19%). Such practices generally occur without medical guidance from oncologists, largely because of poor interactions between parents and oncologists. Future efforts should be made to encourage both parents and oncologists to discuss this issue. Nurses may serve as mediators by developing mutual trust and a sharing relationship between these groups.

Adolescent↗

PubMedDate not supplied

A new triterpene glycoside from Asterias rollentoni.

A new triterpene glycoside, rollentoside A, has been isolated from Asterias rollentoni Bell and identified as 3beta-O-{3-O-methyl-beta-D-xylopyranosyl-(1-->3)-O-beta-D-glucopyranosyl-(1-->4)-O-beta-D-quinopyranosyl-(1-->2)-O-beta-D-xylopyranosyl}-16-beta-acetoxy-23S-acetoxy-holost-7-ene (1), together with a new natural product, rollentoside B (2). The structures of compounds1 and 2 were elucidated by extensive 1D and 2D NMR investigation (1H-1H COSY, TOCSY, HSQC, HMBC, NOESY).

Animals↗

PubMedDate not supplied

Low-molecular-weight peptides derived from extracellular matrix as chemoattractants for primary endothelial cells.

The development of synthetic and naturally occurring scaffolds for tissue engineering applications has included strategies to promote attachment of specific cell types, control the rate of scaffold degradation, encourage angiogenesis, or otherwise modulate the host response. We have reported that bioscaffolds developed from porcine small intestinal submucosa (SIS) facilitate the constructive remodeling of tissues and recruit marrow-derived cells that persist long after the acute inflammatory stages have resolved. We have not yet determined which cells are recruited, the eventual fate of these cells, or via what mechanisms the events occur. We now have analyzed various molecular weight fractions of acid-hydrolyzed SIS by both functional and morphologic methods and have determined that fraction 4 (5 to 16 kDa) possesses chemoattractant activity for primary murine adult liver, heart, and kidney endothelial cells in vitro. Addition of fraction 4 to Matrigel plugs promoted in vivo vascularization when the plugs were implanted subcutaneously in mice. These results indicate that small-molecular-weight peptides derived from the degradation of porcine SIS are biologically active in the recruitment of murine endothelial cells in vitro and in vivo.

Angiogenesis Inducing Agents↗

PubMedDate not supplied

Fluid mechanics of left ventricular assist system outflow housings.

Using the Novacor (Baxter Novacor, Oakland, CA) Left Ventricular Assist System (LVAS) as a test bed, phasic flow patterns were analyzed for three outflow valve housing designs: 1) a triple sinus; 2) an axisymmetric concentric sinus (CS); and 3) a modified triple sinus (MS). The 21 mm Carpentier-Edwards trileaflet pericardial heart valve prosthesis was used for all experiments done on the three housing designs. The LVAS was actuated by a laboratory model of the Novacor LVAS control console, and it was connected to a mock flow loop with an adjustable afterload system to provide physiologic pressures and flows (Pao, 120/80 mmHg; pump output [PO], 2-6 L/min). Laser illuminated flow visualization techniques were used to investigate the phasic flow patterns of the housings, and the visualization derived velocity was verified by laser Doppler velocimetry at several selected points in the field. Formation of vortices behind the leaflets during the LVAS ejection phase was observed in each of the housing designs. They were well organized, and they circulated with the greatest strength in MS. These vortices tended to lie in a plane parallel to the main flow axis, with the rotational velocity increasing with the stroke volume of the LVAS. In the CS and the MS housings, a circumferential flow that provided good washing of this region was observed behind the stents.

Biomechanical Phenomena↗

PubMedDate not supplied

Effects of a conditional Drosophila PKA mutant on olfactory learning and memory.

The requirement for cAMP-dependent protein kinase (PKA) in associative learning of Drosophila was assessed in mutant flies hemizygous for a cold-sensitive allele, X4, of the DC0 gene, which encodes the major catalytic subunit of PKA. DC0X4 hemizygotes died as third-instar larvae at 18 degrees C, the restrictive temperature, but were viable when raised at 25 degrees C. Shifting adult DC0X4 hemizygotes from 25 degrees C to 18 degrees C led to a decrease in PKA activity from 24% to 16% of wild-type without impairing viability. At 25 degrees C, DC0X4 hemizygotes exhibited reduced initial learning relative to controls but normal memory decay in a Pavlovian olfactory learning assay. Shifting the temperature from 25 degrees C to 18 degrees C prior to training reduced initial learning to a similar extent in DC0X4 hemizygotes and controls but resulted in a steeper memory decay curve only in DC0X4 hemizygotes. These observations are suggestive of a role for PKA in medium-term memory formation in addition to its previously established role in initial learning.

Animals↗

PubMedDate not supplied

Overexpression of cyclooxygenase-2 correlates with tumor angiogenesis in endometrial carcinoma.

The inducible enzyme cyclooxygenase-2 (COX-2) is an important mediator of angiogenesis and tumor growth. Several reports have indicated that vascular endothelial growth factor (VEGF)-positive tumors are associated with an increased amount of COX-2 protein. This study evaluated the significance of COX-2 in 34 patients with endometrial carcinoma and its relationship to angiogenesis. Immunohistochemical expression of COX-2 and VEGF was analyzed on paraffin-embedded tissue sections. Microvessel density (MVD) of endometrial carcinoma was also determined with anti-CD(34) as the label. COX-2 messenger RNA (mRNA) was analyzed by reverse transcription-polymerase chain reaction. The expression rate of COX-2 in 34 cases was 64.7% but not in control endometrium. COX-2 mRNA was higher in tumor specimens than in normal tissues. The level of COX-2 expression was higher in grade 2 tumors than in grade 3 tumors (P < 0.05). MVD was higher in COX-2-positive and VEGF-positive cases than in COX-2-negative and VEGF-negative cases (P < 0.05). The expression of COX-2 was positively correlated with the expression of VEGF and MVD (P < 0.05 and P < 0.01, respectively). The present findings suggest that overexpression of COX-2 may induce the expression of VEGF, increase angiogenesis, and enhance tumor growth.

Adult↗

PubMedDate not supplied

Enhanced radiation-mediated cell killing of human cervical cancer cells by small interference RNA silencing of ataxia telangiectasia-mutated protein.

The ataxia telangiectasia-mutated (ATM) protein, which is mutated in the inherited disease ataxia telangiectasia (AT), is a key activator of cell cycle checkpoint, initiating cell response to DNA damage and ensuring genomic stability. AT cells exhibit defects in all cellular responses to ionizing radiation and radiomimetic chemicals. Inactivation of ATM may therefore make cells fail to execute many responses to DNA damage and improve the cells' sensitivity to radiation. Recent developments in the use of small interference RNA molecules (siRNAs) to inhibit specific protein expression have highlighted the potential use of siRNA as a therapeutic agent. In this study, we have designed and exogenously delivered plasmids encoding siRNAs targeting ATM to human cervical carcinoma SiHa cells and generated a stable cell line, SiHa(ATM). SiHa(ATM) cells displayed minimal levels of ATM protein and showed a marked increase in sensitivity to radiation. Together, these data provide strong evidence for the potential use of siRNA as a novel radiation/chemotherapy-sensitizing agent.

Ataxia Telangiectasia↗

PubMedDate not supplied

Low-order polynomial trends of female-to-male map distance ratios along human chromosomes.

Recombination rates in humans tend to be sex specific. For a given map interval delimited by genetic markers, the difference between male and female recombination rates may be measured by the ratio, R, of female-to-male map distance. On average over all chromosomes, R is close to 2, but this ratio is region specific. The spatial variation of R can be captured by a low-order (linear, quadratic, etc.) trend across the length of the chromosome. Chromosome maps have been constructed that take into account such trends. Resulting map distances tend to be more accurate than when such trends are ignored. These maps may be obtained at URL ftp://linkage.rockefeller.edu/SexSpecMaps/.

Chromosome Mapping↗

PubMedDate not supplied

A complete enumeration and classification of two-locus disease models.

There are 512 two-locus, two-allele, two-phenotype, fully penetrant disease models. Using the permutation between two alleles, between two loci, and between being affected and unaffected, one model can be considered to be equivalent to another model under the corresponding permutation. These permutations greatly reduce the number of two-locus models in the analysis of complex diseases. This paper determines the number of nonredundant two-locus models (which can be 102, 100, 96, 51, 50, or 58, depending on which permutations are used, and depending on whether zero-locus and single-locus models are excluded). Whenever possible, these nonredundant two-locus models are classified by their property. Besides the familiar features of multiplicative models (logical AND), heterogeneity models (logical OR), and threshold models, new classifications are added or expanded: modifying-effect models, logical XOR models, interference and negative interference models (neither dominant nor recessive), conditionally dominant/recessive models, missing lethal genotype models, and highly symmetric models. The following aspects of two-locus models are studied: the marginal penetrance tables at both loci, the expected joint identity-by-descent (IBD) probabilities, and the correlation between marginal IBD probabilities at the two loci. These studies are useful for linkage analyses using single-locus models while the underlying disease model is two-locus, and for correlation analyses using the linkage signals at different locations obtained by a single-locus model.

Animals↗

PubMedDate not supplied

Maintenance of differentiated phenotype by mouse type 2 pneumocytes in serum-free primary culture.

An improved method has been developed for separation of an enriched population of mouse type 2 pneumocytes, based on differential adherence and size fractionation of cells dissociated with trypsin. These cells were successfully maintained in primary culture in serum-free medium MCDB 201 supplemented with albumin, transferrin, and lipids. Whereas type 2 pneumocytes in serum-supplemented culture undergo phenotypic transformation into adherent flattened cells that resemble type 1 pneumocytes, this did not occur in serum-free culture. Both the morphology of the type 2 pneumocytes and their expression of surfactant protein A were maintained for at least 6 days in vitro. However, rapid loss of differentiated characteristics was induced by exposure of the cells to normal mouse serum. This was accompanied by a striking decrease in spontaneous DNA synthesis as assessed by incorporation of tritiated thymidine. When cultured in serum-free medium, the behavior of the type 2 pneumocytes on various extracellular matrix components was different from that reported for serum-supplemented culture. Serum-free culture of type 2 pneumocytes may offer significant advantages for evaluation of the secretory activities of these cells in vitro.

Animals↗

PubMedDate not supplied

An empirical model of hyperopic shift with corticosteroid modulation and refractive power prediction after photorefractive keratectomy.

Data from a selected sample of 158 patients who received excimer laser photorefractive keratectomy (PRK) in our center and obtained a desirable refractive outcome at 6-months were analyzed retrospectively to establish an empirical model of refractive power after PRK. This model, generated by a computer-assisted regression program, is presented as a multivariate non-linear quadratic equation. Since the coefficients of each variable (attempted correction and postoperative days) are statistically significant, the estimated influence of the variables on the postoperative refraction from this regression model is reliable and consistent. Therefore, this model has been used to direct the use of corticosteroids for modulating post-PRK refraction. The predictability of this model has also been corroborated by separate data from 1-year follow up of PRK recipients. The recipients whose refraction at 6 months agree with the calculation from this model have obtained an excellent outcome; while those whose refractive outcome deviates from this model have gotten undesirable results.

Computer Simulation↗

PubMedDate not supplied

Laser in situ keratomileusis enhancement after radial keratotomy.

PURPOSE: To present results of laser in situ keratomileusis (LASIK) enhancement after radial keratotomy (RK). METHODS: Sixteen eyes of 10 patients were treated with LASIK for residual myopia and hyperopia after RK. Mean preoperative spherical equivalent refraction was -3.14+/-3.04 D (range, -6.675 to +6.00 D). Best spectacle-corrected visual acuity was 20/20 in 9 eyes, 20/25 in 6 eyes, and 20/30 in 1 eye. Uncorrected visual acuity was better than 20/40 in only 2 eyes. Patients were followed at 1 day, 1 week, 1, 3, and 6 months, and 1 year. Mean follow-up was 8.3 months (range, 1 to 17 mo). RESULTS: All eyes received one LASIK enhancement. Mean final spherical equivalent refraction was +0.16+/-0.68 D (range, -1.00 to +1.75 D). No eyes experienced any visual loss. Five eyes gained 1 line of best spectacle-corrected visual acuity. Uncorrected visual acuity was 20/20 in 9 eyes, 20/25 in 6 eyes, and 20/30 in 1 eye. Two eyes of one patient had the previous RK incisions open. CONCLUSION: LASIK was an effective treatment for correction of residual myopia and hyperopia after RK.

Adult↗

PubMedDate not supplied

[The problem of therapeutic efficacy indices. 1. Elements of the problem].

Efficacy indices measure the efficacy of therapies. They derive, by definition, from two quantities, the basal or control risk of event, Rc, observed in the control group, and the on-treatment risk, Rt, observed in the treated group. In clinical trials and meta-analyses, each is an unbiased measure of efficacy. Although they are a combination of frequencies, these indices are used in clinical practice to predict the benefit in treated patients. Their relevance to express efficacy depends on the type of clinical condition, and is better for acute diseases than for chronic diseases. In order to be useful for prescribers, they should meet certain specifications. In addition, they should be considered in the more general framework of effect models.

Clinical Trials as Topic↗

PubMedDate not supplied

[The problem of therapeutic efficacy indices. 2. Description of the indices].

The four indices for a binary outcome or therapeutic objective are: the odds ratio, the relative risk, the absolute benefit and the number of patients to treat. For a continuous outcome, the effect size is the best choice. The odds ratio approximates the relative risk. The difference may be large in some instances. The number of patients to treat is the reciprocal of the absolute benefit. Although they are built on the same two quantities, they are not interchangeable and should not be considered in the same way. Moreover, their meaning is not straightforward and they can be misused.

Clinical Protocols↗

PubMedDate not supplied

Regulation of signal transduction activity in normal and cancer cells.

UNLABELLED: The purpose of this investigation is to clarify critical aspects of the behavior and regulation of signal transduction activity in normal and cancer cells. MATERIALS AND METHODS: Signal transduction activity was determined by measuring the steady-state activity of the three synthetic enzymes involved in the conversion of 1-phosphatidylinositol to IP3, PI 4-kinase, PI 4-phosphate 5-kinase and phospholipase C. These enzymic activities were opposed by the activities of the degradative enzymes, 4-phosphatase and 5-phosphatase. RESULTS: We observed in hepatocellular carcinomas the operation of an integrated imbalance in signal transduction which was manifested in the up-regulation of the steady-state activities of the three synthetic enzymes and in the reduction of the activities of the two catabolic phosphatases. As a consequence of this enzyme imbalance there was an increase in the concentration of IP3 in hepatomas. Increased IP3 levels were also observed in numerous human carcinomas in clinical samples and in tissue culture cells. The signal transduction activity was subject to nutritional regulation and to drug action. The elevated signal transduction activity, as measured by the IP3 concentration, was down-regulated in a time- and dose-dependent fashion by the anticancer drug, tiazofurin, by the flavonoids, quercetin and genistein, and by the anti-estrogen receptor, tamoxifen. CONCLUSIONS: Our studies show that signal transduction activity is stringently linked with transformation and progression in rat and human carcinomas. Down-regulation of signal transduction activity by various drugs led to a marked reduction of IP3 concentration and then to apoptosis and induced differentiation.

Animals↗

PubMedDate not supplied

[Outline of the problem of indices of therapeutic efficacy. 4. Expression of efficacy when the underlying illness is incurable. Study Group for the Indices of Efficacy].

In chronic illness, when death or a non-fatal event can occur at any time, the current efficacy indices are no longer appropriate to express the effect of the treatment on the potential therapeutic objectives. The inappropriateness is not dependent on the effect model. Clues for solutions are proposed.

Chronic Disease↗

PubMedDate not supplied

[The problem of therapeutic efficacy indices. 3. Comparison of the indices and their use].

Efficacy indices do not contain the same information although they are all combinations of the same two quantities. Therefore, one should choose the proper index. Actually, none is entirely appropriate. Each more or less meets the specifications, depending on the underlying effect model for the therapy considered. However, one can say that the absolute benefit is more appropriate from the patient's point of view, the relative from the scientific point of view and the number of patients to treat from the policy maker's point of view. Nevertheless, this classification needs to be considered with caution. Finally, it emerges from the review that none is fully relevant to express the efficacy of a therapy, even in the most suitable condition, the acute illness.

Drug Evaluation↗

PubMedDate not supplied

Metastatic melanoma to regional lymph nodes.

There is an epidemic of melanoma in the United States and throughout most parts of the word. Recent advancements in the management of this disease has provided the patient with more options. The emerging technology of lymphatic mapping and sentinel node biopsy results in a more conservative, less morbid procedure to obtain nodal staging information. At the same time, providing the pathologist the 1-2 nodes from the basin most likely to contain metastatic disease, allows for a more detailed examination of the sentinel lymph node. This more detailed examination may include serial sectioning, immunohistochemical staining or even molecular biology techniques based on RT-PCR to provide more accurate staging. National trials are ongoing to examine the clinical relevance of the disease that is detected and the 'upstaging' that occurs with more sensitive assays for occult metastases.

Clinical Trials as Topic↗