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Biomedical subjects

Weichung Joe Shih

Publications and source records attributed to Weichung Joe Shih.

15 recordsLinked to original sources
PubMed2006

Caffeine and caffeine sodium benzoate have a sunscreen effect, enhance UVB-induced apoptosis, and inhibit UVB-induced skin carcinogenesis in SKH-1 mice.

Topical application of caffeine sodium benzoate (caffeine-SB) immediately after UVB irradiation of SKH-1 mice enhanced UVB-induced apoptosis by a 2- to 3-fold greater extent than occurred after the topical application of an equimolar amount of caffeine. Although topical application of caffeine-SB or caffeine enhanced UVB-induced apoptosis, both substances were inactive on non-UVB-treated normal skin. Topical application of caffeine-SB or caffeine (each has UVB absorption properties) 0.5 h before irradiation with a high dose of UVB decreased UVB-induced thymine dimer formation and sunburn lesions (sunscreen effect). Caffeine-SB was more active than an equimolar amount of caffeine in exerting a sunscreen effect. In additional studies, caffeine-SB strongly inhibited the formation of tumors in UVB-pretreated 'high-risk mice' and in tumor-bearing mice, and the growth of UVB-induced tumors was also inhibited. Caffeine-SB and caffeine are the first examples of compounds that have both a sunscreen effect and enhance UVB-induced apoptosis. Our studies suggest that caffeine-SB and caffeine may be good agents for inhibiting the formation of sunlight-induced skin cancer.

Administration, Topical↗
PubMed2006

Effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) in combination with paclitaxel (Taxol) on prostate Cancer LNCaP cells cultured in vitro or grown as xenograft tumors in immunodeficient mice.

PURPOSE: To investigate the effects of 12-O-tetradecanoylphorbol-13-acetate (TPA) in combination with paclitaxel (Taxol) on prostate cancer cells cultured in vitro or grown as tumors in immunodeficient mice. EXPERIMENTAL DESIGN: Human prostate cancer LNCaP cells in culture were treated with TPA alone or in combination with paclitaxel. NCr immunodeficient mice with well-established LNCaP tumors received i.p. injections with vehicle or with TPA, paclitaxel, or TPA in combination with paclitaxel. The animals either received daily treatment for 5 consecutive days followed by a 2-day intermission, which was repeated for a total of 28 days (experiment 1), or continuous daily treatment for 28 days (experiment 2). RESULTS: Treatment of LNCaP cells with a combination of TPA and paclitaxel synergistically inhibited the growth and induced apoptosis in cultured LNCaP cells, and this treatment also induced a marked increase in phosphorylated c-Jun-NH2-kinase (JNK). In animal experiments, tumor growth occurred in all mice treated with vehicle. When treated with TPA alone, the percentage of animals with some tumor regression was 33% in experiment 1 and 100% in experiment 2. Treatment of animals with paclitaxel alone caused some tumor regression in 17% and 57% of the animals in experiments 1 and 2, respectively. All animals treated with TPA + paclitaxel in both experiments had some tumor regression. CONCLUSIONS: TPA and paclitaxel in combination had a stronger inhibitory effect on the growth of LNCaP cells in culture or as xenograft tumors in immunodeficient mice than either agent alone. Clinical trials with TPA alone or in combination with paclitaxel in patients with prostate cancer may be warranted.

Animals↗
PubMed2006

Inhibitory effects of voluntary running wheel exercise on UVB-induced skin carcinogenesis in SKH-1 mice.

Earlier studies showed that oral administration of green tea or caffeine to SKH-1 mice inhibited ultraviolet B light (UVB)-induced skin carcinogenesis, decreased dermal fat thickness and increased locomotor activity. In the present study, the effects of voluntary running wheel exercise on thickness of dermal fat as well as on UVB-induced tumorigenesis in SKH-1 mice were studied in UVB-initiated high-risk and UVB-induced complete carcinogenesis models. In the high-risk model, animals were exposed to UVB (30 mJ/cm(2)) 3 times/week for 16 weeks. For 14 weeks subsequent to UVB exposure, half of the animals had access to running wheels in their cages whereas the other half did not. In the complete carcinogenesis model, animals were exposed to UVB (30 mJ/cm(2)) 2 times/week for 33 weeks. From the beginning, half of the animals had access to running wheels whereas the other half did not. At the conclusion of each study, body weights were not different between groups, although animals with running wheels consumed significantly more food and water than animals without running wheels. In addition, animals with running wheels had decreases in parametrial fat pad weight and thickness of the dermal fat layer. In both UVB-initiated high-risk and complete carcinogenesis models, voluntary running wheel exercise delayed the appearance of tumors, decreased the number of tumors per mouse and decreased tumor volume per mouse. Histopathology studies revealed that running wheel exercise decreased the number of non-malignant tumors (primarily keratoacanthomas) by 34% and total tumors per mouse by 32% in both models, and running wheel exercise decreased the formation of squamous cell carcinomas in the UVB-induced complete carcinogenesis model by 27%. In addition, the size of keratoacanthomas and squamous cell carcinomas were decreased substantially in both models. The effects described here indicate that voluntary running wheel exercise inhibits UVB-induced skin tumorigenesis and may also inhibit tumor growth.

Adipose Tissue↗
PubMed2006

Plan to be flexible: a commentary on adaptive designs.

This is a discussion of the following three papers appearing in this special issue on adaptive designs: 'Nested repeated confidence intervals and switching between noninferiority and superiority' by Joachim Hartung and Guido Knapp; 'Confirmatory Seamless Phase II/III Clinical trials with Hypotheses Selection at Interim: General Concepts' by Frank Bretz, Heinz Schmidli, Franz König, Amy Racine and Willi Maurer; and 'Confirmatory Seamless Phase Il/III Clinical Trials with Hypotheses Selection at Interim: Applications and Practical Considerations' by Heinz Schmidli, Frank Bretz, Amy Racine and Willi Maurer.

Biometry↗
PubMed2005

Inhibition of intestinal tumorigenesis in Apcmin/+ mice by (-)-epigallocatechin-3-gallate, the major catechin in green tea.

The present study was designed to investigate the effects of two main constituents of green tea, (-)-epigallocatechin-3-gallate (EGCG) and caffeine, on intestinal tumorigenesis in Apc(min/+) mice, a recognized mouse model for human intestinal cancer, and to elucidate possible mechanisms involved in the inhibitory action of the active constituent. We found that p.o. administration of EGCG at doses of 0.08% or 0.16% in drinking fluid significantly decreased small intestinal tumor formation by 37% or 47%, respectively, whereas caffeine at a dose of 0.044% in drinking fluid had no inhibitory activity against intestinal tumorigenesis. In another experiment, small intestinal tumorigenesis was inhibited in a dose-dependent manner by p.o. administration of EGCG in a dose range of 0.02% to 0.32%. P.o. administration of EGCG resulted in increased levels of E-cadherin and decreased levels of nuclear beta-catenin, c-Myc, phospho-Akt, and phospho-extracellular signal-regulated kinase 1/2 (ERK1/2) in small intestinal tumors. Treatment of HT29 human colon cancer cells with EGCG (12.5 or 20 micromol/L at different times) also increased protein levels of E-cadherin by 27% to 58%, induced the translocation of beta-catenin from nucleus to cytoplasm and plasma membrane, and decreased c-Myc and cyclin D1 (20 micromol/L EGCG for 24 hours). These results indicate that EGCG effectively inhibited intestinal tumorigenesis in Apc(min/+) mice, possibly through the attenuation of the carcinogenic events, which include aberrant nuclear beta-catenin and activated Akt and ERK signaling.

Animals↗
PubMed2005

Inhibitory effects of 12-O-tetradecanoylphorbol-13-acetate alone or in combination with all-trans retinoic acid on the growth of cultured human pancreas cancer cells and pancreas tumor xenografts in immunodeficient mice.

Treatment of cultured PANC-1, MIA PaCa-2, and BxPC-3 human pancreatic adenocarcinoma cells with 0.1 to 1.6 nM 12-O-tetradecanoylphorbol-13-acetate (TPA) for 96 h inhibited the proliferation of these cells in a dose-dependent manner, and PANC-1 and MIA PaCa-2 cells were more sensitive to TPA than BxPC-3 cells. Inhibition of proliferation by TPA in PANC-1 cells was associated with an increase in the level of p21, but this was not observed in MIA PaCa-2 or BxPC-3 cells. The TPA-induced increase of p21 in PANC-1 cells was blocked by bisindolylmaleimide or rottlerin (inhibitors of protein kinase C). Studies in NCr-immunodeficient mice with well established PANC-1 tumor xenografts indicated that daily i.p. injections of TPA strongly inhibited tumor growth, increased the percentage of caspase-3-positive cells, and decreased the ratio of mitotic cells to caspase-3-positive cells in the tumors. Studies with BxPC-3 tumors in NCr mice receiving daily i.p. injections of vehicle, TPA, all-trans retinoic acid (ATRA), or a TPA/ATRA combination showed that TPA had an inhibitory effect on tumor growth, but treatment of the animals with the TPA/ATRA combination had a greater inhibitory effect on tumor growth than TPA alone. Treatment with the TPA/ATRA combination resulted in a substantially decreased ratio of the percentage of mitotic cells to the percentage of caspase-3-positive cells in the tumors compared with tumors from the vehicle-treated control animals. The inhibitory effects of TPA on tumor growth occurred at clinically achievable blood levels.

Animals↗
PubMed2005

Synergistic stimulatory effect of 12-O-tetradecanoylphorbol-13-acetate and capsaicin on macrophage differentiation in HL-60 and HL-525 human myeloid leukemia cells.

Our previous studies demonstrated that 12-O-tetradecanoylphorbol-13-acetate (TPA) had pharmacological activity for the treatment of myeloid leukemia patients. In the present study, we investigated the effects of TPA alone or in combination with capsaicin (8-methyl-N-vanillyl-6-nonenamide) on growth and differentiation in myeloid leukemia HL-60 cells and in a TPA-resistant HL-60 variant cell line termed HL-525. Treatment of HL-60 cells with TPA (0.16-1.6 nM) for 48 h resulted in concentration-dependent growth inhibition and cell differentiation (via the macrophage pathway). Capsaicin (5-50 microM) inhibited the growth of HL-60 cells in a concentration-dependent manner. Treatment of HL-60 cells with capsaicin alone only resulted in a small increase in the number of differentiated cells but treatment of the cells with TPA in combination with capsaicin synergistically increased differentiation. Moreover, inhibitors of protein kinase C (PKC), 7-hydroxystaurosporin (UCN-01; 100 nM) and chelerythrine (0.5 microM), significantly decreased HL-60 cell differentiation induced by the combination of TPA and capsaicin. These results suggest that PKC may be involved in HL-60 cell differentiation induced by TPA in combination with capsaicin. Capsaicin alone caused a very small increase in differentiation in the TPA-resistant HL-525 cells. However, treatment of HL-525 cells with combinations of TPA (0.16 nM) and capsaicin (10-50 microM) caused a strong synergistic increase in differentiation. Results from the present study suggest that a combination of TPA and capsaicin may improve the therapeutic efficacy of TPA and overcome resistance to TPA in some myeloid leukemia patients.

Alkaloids↗
PubMed2004

A mixture model for estimating the local false discovery rate in DNA microarray analysis.

MOTIVATION: Statistical methods based on controlling the false discovery rate (FDR) or positive false discovery rate (pFDR) are now well established in identifying differentially expressed genes in DNA microarray. Several authors have recently raised the important issue that FDR or pFDR may give misleading inference when specific genes are of interest because they average the genes under consideration with genes that show stronger evidence for differential expression. The paper proposes a flexible and robust mixture model for estimating the local FDR which quantifies how plausible each specific gene expresses differentially. RESULTS: We develop a special mixture model tailored to multiple testing by requiring the P-value distribution for the differentially expressed genes to be stochastically smaller than the P-value distribution for the non-differentially expressed genes. A smoothing mechanism is built in. The proposed model gives robust estimation of local FDR for any reasonable underlying P-value distributions. It also provides a single framework for estimating the proportion of differentially expressed genes, pFDR, negative predictive values, sensitivity and specificity. A cervical cancer study shows that the local FDR gives more specific and relevant quantification of the evidence for differential expression that can be substantially different from pFDR. AVAILABILITY: An R function implementing the proposed model is available at http://www.geocities.com/jg_liao/software

Algorithms↗
PubMed2004

Inhibitory effect of 12-O-tetradecanoylphorbol-13-acetate alone or in combination with all-trans-retinoic acid on the growth of LNCaP prostate tumors in immunodeficient mice.

Clinically achievable concentrations of 12-O-tetradecanoylphorbol-13-acetate (TPA; 0.16-0.32 nM) and all-trans-retinoic acid (ATRA; 0.5-1 micro M) had a synergistic inhibitory effect on the growth of cultured LNCaP prostate cancer cells, and apoptosis was markedly stimulated. In additional studies, NCr immunodeficient mice received s.c. injection with LNCaP cells in Matrigel. After 4-6 weeks, mice with well-established tumors received i.p. injection with vehicle, TPA (0.16 nmol/g body weight), ATRA (0.5 nmol/g body weight), or TPA+ATRA in vehicle once a day for 46 days. Tumor growth occurred in all of the vehicle-treated control mice. The percentage of animals with some tumor regression after 21 days of treatment was 0% for the control group, 31% for the ATRA group, 62% for the TPA group, and 100% for the TPA+ATRA group (13 mice/group). Although treatment of the mice with TPA or TPA+ATRA continued to inhibit tumor growth for the duration of the 46-day study, treatment of the mice with ATRA alone did not inhibit tumor growth beyond 28 days of daily injections (6 mice/group). Mechanistic studies indicated that treatment of the mice with TPA or TPA+ATRA for 46 days increased apoptosis in the tumors, and treatment with TPA+ATRA also decreased the mitotic index. Because the dose of TPA used in this study was effective and resulted in clinically achievable blood levels, clinical trials with TPA alone or in combination with ATRA in patients with prostate cancer may be warranted.

Animals↗
PubMed2004

Use of joint models to assess treatment effects on disease markers and clinical events: the Proscar Long-Term Efficacy and Safety Study (PLESS).

Clinical trials often collect longitudinal measurements of a disease marker and time to a major clinical event of the disease to assess treatment effects. It makes sense to combine the treatment effects on both the longitudinal disease marker and the time to clinical event, especially when the clinical event is also mediated through the disease marker over time. In this paper we apply a joint modeling approach in the assessment of the treatment effects in treating benign prostatic hyperplasia (BPH) for the Proscar Long-Term Efficacy and Safety Study (PLESS).

Biomarkers↗
PubMed2003

Patterns of recurrence in patients with melanoma and histologically negative but RT-PCR-positive sentinel lymph nodes.

BACKGROUND: We studied the patterns of recurrence of patients with only reverse transcriptase-polymerase chain reaction (RT-PCR) evidence of regional nodal spread to see whether or not proposed treatment interventions are likely to be effective. STUDY DESIGN: One hundred seventy-five patients who underwent selective lymphadenectomy for clinical stage I and II melanomas were included in this analysis. We preserved a portion of each sentinel lymph node (SLN) in liquid nitrogen in the operating room and performed RT-PCR on the specimens to detect the melanoma/melanocyte-specific marker tyrosinase. We then compared the pattern of recurrence (regional dermal metastases, regional nodal recurrence, or distant metastatic spread) of the patients with histologically positive SLNs to that of patients who had histologically negative SLNs. RESULTS: The mean followup time of the 175 patients was 33.83 months (SD = 15.94, median = 34.17, maximum = 62.95, minimum = 6.21). Thirty-four patients had at least one histologically positive SLN, and 17 of these patients had a recurrence (50%). Of the 141 patients that had histologically negative SLNs, 73 had SLNs that were also negative for tyrosinase by RT-PCR, and none of these patients had a recurrence. Of the 68 patients that had histologically negative but RT-PCR-positive SLNs, 14 had a recurrence (20.6%). CONCLUSIONS: Because the pattern of recurrence of patients with only RT-PCR evidence of melanoma in SLNs was identical to that in patients who had histologically evident melanoma in the SLN and underwent subsequent completion lymphadenectomy, we conclude that completion lymphadenectomy might be ineffective in decreasing the recurrence rate of patients with only RT-PCR evidence of melanoma in SLNs.

Biomarkers, Tumor↗
PubMed2002

Implications of radioactive seed migration to the lungs after prostate brachytherapy.

OBJECTIVES: To review the incidence and the impact of pulmonary seed migration after prostate brachytherapy on lung function. Isolated reports of seed migration to the lungs after prostate brachytherapy have been published; however, the clinical consequences of this pulmonary migration have not been adequately evaluated. METHODS: We performed a retrospective review of patients undergoing prostate brachytherapy from 1998 to 2000. Pulmonary imaging with chest x-ray was performed 15 to 90 days (median 45) after the procedure. The chest radiographs were reviewed by a single radiologist (V.S.D.), and patients with seed migration to the lungs were evaluated by a single pulmonologist (A.M.H.) using a questionnaire, chest radiography, and pulmonary function tests. Computed tomography of the prostate after seed implantation was performed to check seed position and dosimetry. Odds ratio, confidence intervals, chi-square tests, and logistic regression analysis were performed to evaluate the relationship between the type and number of seeds used, the incidence of pulmonary migration, and the effects on pulmonary function. RESULTS: A total of 83 patients underwent prostate brachytherapy during the study period and 58 patients underwent chest radiography. Seed migration occurred in 21 (36.2%) of 58 patients (95% confidence interval 23.8% to 48.6%). Thirty-four (0.71%) of 4755 seeds used migrated to the lungs. Nine patients had single seed migration to the right lung and three to the left lung. Nine patients had multiple (maximum of 4) and bilateral seed migration. No consistent relationship was found between seed migration and the type of seeds used (P = 0.24). Borderline statistical significance suggested an increased incidence of seed migration with an increasing number of implanted seeds (P = 0.054). Repeat chest radiography in 21 patients revealed no delayed migration at a median follow-up of 16 months. Clinical and pulmonary function testing revealed no consistent abnormality attributable to seed migration. CONCLUSIONS: Radioactive seed migration occurred in 36.2% of brachytherapy patients who had chest radiographs done in our series. Pulmonary seed migration may be influenced by the number of implanted seeds and does not appear to be influenced by the seed type. Additional study of this observed phenomenon is required. A thorough pulmonary workup failed to reveal any short-term harmful side effects; however, long-term follow-up is needed. Healthcare providers should discuss the possibility of pulmonary seed migration with patients with prostate cancer considering prostate brachytherapy.

Brachytherapy↗
PubMed2002

Stimulatory effect of topical application of caffeine on UVB-induced apoptosis in mouse skin.

In an earlier study, we showed that oral administration of green tea or caffeine to SKH-1 mice for 2 weeks prior to a single application of UVB enhanced UVB-induced increases in the number of p53-positive cells, p21(WAF1/CIP1)-positive cells, and apoptotic sunburn cells in the epidermis. In the present study, we found that topical application of caffeine, a major chemopreventive agent in tea, to the dorsal skin of SKH-1 mice immediately after irradiation with UVB (30 mJ/cm2) enhanced UVB-induced apoptosis as measured by the number of morphologically distinct epidermal apoptotic sunburn cells and the number of caspase 3-positive cells. Time course studies indicated that UVB-induced increases in apoptotic sunburn cells were correlated with elevated levels of caspase 3, a key protease that becomes activated during an early stage of apoptosis. Topical application of caffeine immediately after UVB enhanced UVB-induced increases in caspase 3 (active form)-immunoreactive-positive cells and in caspase 3 enzyme activity in the epidermis. Topical application of caffeine had only a small stimulatory effect on UVB-induced increases in the level of wild-type p53 protein and these changes were not related temporally to caffeine-induced increases in apoptotic cells. There was little or no effect of topical applications of caffeine on epidermal cell proliferation as determined by bromodeoxyuridine (BrdU) incorporation into DNA. Topical application of (-)-epigallocatechin gallate (EGCG) to the dorsal skin of mice immediately after irradiation with UVB had a small inhibitory effect on UVB-induced increases in BrdU-positive cells in the basal layer of the epidermis, but this treatment had no effect on UVB-induced increases in apoptotic sunburn cells. The results of this study indicate a proapoptotic effect of topical application of caffeine on UVB-irradiated mouse skin.

Administration, Topical↗
PubMedDate not supplied

Heart rate variability biofeedback increases baroreflex gain and peak expiratory flow.

OBJECTIVE: We evaluated heart rate variability biofeedback as a method for increasing vagal baroreflex gain and improving pulmonary function among 54 healthy adults. METHODS: We compared 10 sessions of biofeedback training with an uninstructed control. Cognitive and physiological effects were measured in four of the sessions. RESULTS: We found acute increases in low-frequency and total spectrum heart rate variability, and in vagal baroreflex gain, correlated with slow breathing during biofeedback periods. Increased baseline baroreflex gain also occurred across sessions in the biofeedback group, independent of respiratory changes, and peak expiratory flow increased in this group, independently of cardiovascular changes. Biofeedback was accompanied by fewer adverse relaxation side effects than the control condition. CONCLUSIONS: Heart rate variability biofeedback had strong long-term influences on resting baroreflex gain and pulmonary function. It should be examined as a method for treating cardiovascular and pulmonary diseases. Also, this study demonstrates neuroplasticity of the baroreflex.

Adult↗