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Biomedical subjects

David S Alberts

Publications and source records attributed to David S Alberts.

At least 19 recordsLinked to original sources
PubMed2007

Serum 25(OH)D levels, dietary intake of vitamin D, and colorectal adenoma recurrence.

There is strong epidemiological and laboratory evidence that vitamin D may be protective against colorectal neoplasia. Therefore, we sought to assess the relationship between serum 25(OH)D levels, dietary intake of vitamin D, and colorectal adenoma recurrence in our ursodeoxycholic acid trial. A total of 568 participants were randomly selected for analysis of serum 25(OH)D levels. The range of total 25(OH)D was 5.5-66.1 ng/ml, with a median of 25.6 ng/ml. After categorizing 25(OH)D levels into tertiles based on the population distribution, the adjusted odds ratios (95% CI) for adenoma recurrence in the second and third tertiles were 0.88 (0.56-1.39) and 0.78 (0.49-1.24), respectively. The association between serum 25(OH)D and adenoma recurrence appeared to be stronger among women than men. As compared to those below the median value, women with serum 25(OH)D levels above the median had an OR (95% CI) of 0.59 (0.30-1.16); the corresponding OR (95% CI) for men was 0.95 (0.60-1.49). Analyses by dietary vitamin D intake revealed no statistically significant associations. In summary, the results of this study show a moderate, nonsignificant inverse association between serum 25(OH)D levels and reduced risk for colorectal adenoma recurrence, particularly among women.

Adenoma↗
PubMed2006

Cancer chemoprevention and cancer preventive vaccines--a call to action: leaders of diverse stakeholder groups present strategies for overcoming multiple barriers to meet an urgent need.

The emerging field of cancer prevention through chemoprevention agents and cancer vaccines offers significant promise for reducing suffering and death from cancer. However, that promise may not be kept unless major barriers to progress are lowered or eliminated. Among the most significant barriers are the relatively small investment from government and industry in research and development of cancer preventive agents; a predominant emphasis of translational cancer research on therapeutic interventions for metastatic or advanced cancer; complexities of prevention trial design; a relatively uncharted Food and Drug Administration (FDA) approval process for preventive agents; insufficient public and patient understanding of the importance and potential for cancer preventive measures, with consequent unpredictable public and patient willingness to take preventive agents; an uncertain reimbursement from payors; and limitations in patent law, liability protection, and data package exclusivity that undermine the opportunity for recouping investment. Viewed individually or collectively, each of these barriers serves as a substantial deterrent to intellectual and financial investment by all sectors of the cancer community. In an effort to ultimately overcome these barriers, a Cancer Prevention Research Summit was assembled June 12-13, 2006 in Bethesda, Maryland, organized by C-Change with support from the AACR. The Summit brought together some 120 leaders from private, public, and not-for-profit entities, including cancer researchers and clinicians; federal health officials; regulatory agency representatives; pharmaceutical, biotech, and food industry leaders; patent attorneys; economists; public and private provider group executives; and advocates. Participants engaged in a detailed process to more carefully define the major barriers, identify potential solutions, and formulate initial priorities and recommendations for action. At the conclusion of this dialogue among experts, the following recommended actions were outlined: define policy solutions to patent, intellectual property, and liability law barriers; create an advisory document about the approval process for cancer chemopreventive agents and vaccines for the FDA; develop new design models for cancer chemopreventive clinical trials; outline the business case for chemopreventive agents and vaccines for federal research agencies, payors and investors; and implement a communications strategy to increase public awareness about the importance of chemoprevention and cancer preventive vaccines.

Anticarcinogenic Agents↗
PubMed2006

Reproducibility and expression of skin biomarkers in sun-damaged skin and actinic keratoses.

OBJECTIVES: To explore p53 and proliferating cell nuclear antigen (PCNA) expression and polyamine content as biomarkers in skin cancer chemoprevention trials, we evaluated their expression in early stages of UV-induced squamous cell tumorigenesis. METHODS: Biopsies were collected from three groups: 78 subjects with sun damage on forearms, 33 with actinic keratosis (AK) on forearms, and 32 with previous squamous cell carcinoma. Participants with sun damage were randomized to sunscreen or no sunscreen. RESULTS: We found significant differences in p53 and polyamines in forearms from the sun-damaged group (11.5 +/- 1.2% for p53, 65.5 +/- 1.9 nmol/g for putrescine, and 187.7 +/- 3.3 nmol/g for spermidine) compared with the group with sun damage plus AK (20.9 +/- 2.3% for p53, P = 0.0001; 81.7 +/- 3.9 nmol/g for putrescine, P = 0.0001; 209.4 +/- 8.2 nmol/g for spermidine, P < 0.06). PCNA was not different. When lesion histology was considered, there was a stepwise significant increase in p53 in biopsies without characteristics of AK compared with early AK (P = 0.02) and AK (P = 0.0006) and a similar pattern for PCNA with the only significant difference between early AK and AK. There was a stepwise increase in putrescine and spermidine in normal, sun-damaged forearm, forearm from subjects with AK, and the AK lesion itself (P < 0.0001). No significant differences in p53 or polyamines were seen in 3-month biopsies or, as a result of sunscreen use, although PCNA in the sun-damaged group not using sunscreen decreased significantly. CONCLUSIONS: p53 expression and polyamines in skin were elevated in early stages of skin tumorigenesis and were not affected by sunscreen, adding validity to their use as biomarkers in skin cancer chemoprevention trials.

Adult↗
PubMed2006

Folate fortification, plasma folate, homocysteine and colorectal adenoma recurrence.

In 1996, the US Food and Drug Administration mandated the fortification of grain products with folic acid, a nutrient that has been associated with lower risk of colorectal neoplasia. We assessed the relation of plasma folate and homocysteine and colorectal adenoma recurrence separately in 2 studies: the first involved an intervention of a cereal supplement that contained folic acid, wheat bran fiber (WBF), and the second was conducted primarily during postfortification of the food supply using ursodeoxycholic acid (UDCA). Analyses were stratified for multivitamin use. Results show that plasma folate and homocysteine concentrations were associated with adenoma recurrence among nonusers of multivitamins only. Among nonmultivitamin users, the odds ratio [OR] (95% confidence interval [CI]) for those in the highest versus the lowest folate quartile was 0.65 (0.40-1.06) for the WBF study and 0.56 (0.31-1.02) for the UDCA; likewise, individuals in the highest versus the lowest quartile of homocysteine had higher odds of adenoma recurrence, in both the WBF (OR = 2.25; 95% CI = 1.38-3.66) and UDCA (OR = 1.93; 95% CI = 1.07-3.49) populations. Analyses comparing multivitamin users to different plasma folate concentrations among nonusers show that odds of recurrence for supplement users was lower only when compared to nonusers who had lower concentrations. Our results show that higher plasma folate or lower homocysteine levels are associated with lower odds of recurrence among nonusers of multivitamins in both studies. Our finding, suggesting that multivitamins or supplemental folate only benefit individuals with lower plasma folate concentrations, should be taken into consideration when designing and interpreting results of intervention studies.

Adenoma↗
PubMed2006

Dietary factors and biomarkers involved in the methylenetetrahydrofolate reductase genotype-colorectal adenoma pathway.

BACKGROUND & AIMS: Methylenetetrahydrofolate reductase (MTHFR) is involved in intracellular folate homeostasis and metabolism. We assessed 2 polymorphisms in the MTHFR gene (C677T and A1298C) in relation to colorectal adenoma recurrence and conducted analyses to investigate their joint effects with plasma and dietary markers of folate status. METHODS: We prospectively analyzed data from 1598 individuals genotyped for the C677T polymorphism and 1583 with data on A1298C. RESULTS: Among nonusers of multivitamin supplements, compared with wild-type carriage, higher odds of recurrence were observed for those with the 677 TT variant (odds ratio [OR], 1.66; 95% confidence interval [CI], 1.04-2.63) and a nonsignificant increase was observed among those with the 1298 CC variant (OR, 1.50; 95% CI, 0.93-2.40). Diplotype analyses among nonusers of multivitamins showed that individuals who carry the MTHFR 677TT_1298AA or 677CC_1298CC combination were significantly more likely to have a recurrence compared with those with the double wild-type (OR, 2.05 for TT_AA and 1.85 for CC_CC). Higher odds of recurrence were observed among participants with low folate intake or plasma folate and the 677 TT or 1298 CC variants compared with those with lower levels and the wild-type or heterozygous genotypes. Stronger associations were shown for the combination of high homocysteine and the 677 TT variant (OR, 2.29; 95% CI, 1.00-5.26) but not the 1298 CC variant (OR, 1.09; 95% CI, 0.39-3.01). CONCLUSIONS: We propose that the effect of the MTHFR genotypes on increasing risk of adenoma recurrence in the presence of a low folate status is through their increase in homocysteine concentrations, which in turn could result in DNA hypomethylation via pathways involving S-adenosylhomocysteine.

Adenoma↗
PubMed2006

Selenium supplementation and colorectal adenomas: an analysis of the nutritional prevention of cancer trial.

Selenium status has been inversely associated with colorectal cancers (CRC) and adenomas. This investigation evaluates the association between selenium supplementation and prevalent and incident colorectal adenomas and CRC detected during the Nutritional Prevention of Cancer trial follow-up. Of the 1,312 randomized to 200 mcg of selenized yeast of matching placebo, 598 participants underwent endoscopic screening (flexible sigmoidoscopy or colonoscopy) for CRC sometime during the follow-up period, which ended in February 1, 1996. There was no colorectal screening performed at baseline. Of those screened, 77% were male (with a mean age of 62.8 years), 42% were former and 25% were current smokers. Adenomas were classified as prevalent (identified at the first endoscopic examination post-randomization during the follow-up period) or incident (identified at the second or subsequent examination). Ninety-nine prevalent and 61 incident adenomas were ascertained. Logistic regression odds ratios (OR) and 95% confidence intervals (CI) were calculated, adjusting for age, gender and smoking status. For prevalent adenomas, there was a suggestive but nonsignificant decrease in risk associated with selenium treatment (OR = 0.67, 95% CI = 0.43-1.05). Subjects in the lowest tertile of baseline selenium (OR = 0.27, 95% CI = 0.09-0.77) and current smokers (OR = 0.27, 95% CI = 0.11-0.66) had significant reductions in risk. The OR for incident adenomas was 0.98 (95% CI = 0.57-1.68). In addition to being associated with a reduced risk of incident CRC, selenium supplementation was associated with a significantly reduced risk of prevalent adenomas, but only among subjects with either a low baseline selenium level or among current smokers.

Adenoma↗
PubMed2006

Pretreatment CA-125 and risk of relapse in advanced ovarian cancer.

PURPOSE: A previous report suggested the nadir serum CA-125 level within the group of patients with ovarian cancer who achieved normalization of CA-125 accurately defined the risk of relapse. Using similar CA-125 subgroups, we sought to determine if the baseline CA-125 level before initiation of maintenance chemotherapy in women achieving a clinically-defined complete response to primary chemotherapy would be of prognostic value. PATIENTS AND METHODS: Patients included in this retrospective analysis had been treated on one of two previously reported trials of maintenance chemotherapy (three v 12-monthly cycles of paclitaxel; oral altretamine), with a baseline CA-125 level of < or = 35 u/mL. Progression-free survival (PFS) from study entry was analyzed by the Cox regression model. RESULTS: The distribution of premaintenance baseline CA-125 levels for the 384 patients was 58%, 34%, and 8% for values of (A) < or = 10 u/mL, (B) 11 to 20 u/mL, and (C) 21 to 35 u/mL, respectively. The baseline CA-125 was highly statistically significant, either as a categoric variable (P < .001) or as a continuous variable (P < .0001). Median PFS was 24 months, 17 months, and 7 months for groups (A), (B), and (C), respectively. There was no evidence the CA-125 effect differed by trial or treatment in an interaction analysis (P = .70). CONCLUSION: The baseline CA-125 level before initiation of maintenance chemotherapy strongly predicts the risk of subsequent relapse. Patients with premaintenance baseline CA-125 values < or = 10 u/mL have a superior PFS compared with higher levels in the normal CA-125 range.

Aged↗
PubMed2006

Maximizing the delivery of intraperitoneal therapy while minimizing drug toxicity and maintaining quality of life.

This decade has witnessed three large randomized trials (SWOG 8501/GOG 104, GOG 114, and GOG 172) clearly showing the advantages of intraperitoneal (IP) chemotherapy over systemic/intravenous therapy in treating selected patients with advanced stage ovarian cancer. Despite showing an impressive increase in median progression-free survival and median overall survival, complications in IP chemotherapy delivery and drug-related toxicities reported in these studies have hindered widespread acceptance and implementation of first-line IP therapy. Some of these complications and drug-related toxicities are treatment-limiting and need special attention. Success of IP therapy as a first-line choice of treatment is dependent upon ideal patient selection, effective delivery of appropriate doses of chemotherapy agents to the tumor site, and efficient management of complications. With proper orientation and instruction in IP catheter placement and patient management, these obstacles can be overcome, allowing for successful administration of IP therapies. This review article discusses clinical approaches to maximize the delivery of IP therapy while minimizing catheter complications. Mitigating drug toxicities with the use of cytoprotectants such as amifostine and preventing infection with the use of agents, such as amifostine and pegfilgrastim, are discussed in detail.

Amifostine↗
PubMed2006

Fiber, sex, and colorectal adenoma: results of a pooled analysis.

BACKGROUND: Evidence for an association between dietary fiber and colorectal neoplasia has been equivocal, and some data suggest that there may be sex differences in response to fiber. OBJECTIVE: We sought to determine whether fiber affects colorectal adenoma recurrence differently in men and women by combining the study populations of 2 large clinical intervention trials: the Wheat Bran Fiber Trial and the Polyp Prevention Trial. DESIGN: Data from 3209 participants combined from 2 trials were analyzed with logistic regression models to examine the effect of a dietary intervention on colorectal adenoma recurrence in the pooled population as a whole and by sex. RESULTS: The adjusted odds ratio for adenoma recurrence for those in the intervention group of either the Wheat Bran Fiber Trial or the Polyp Prevention Trial was 0.91 (95% CI: 0.78, 1.06). For men, the intervention was associated with statistically significantly reduced odds of recurrence with an odds ratio of 0.81 (95% CI: 0.67, 0.98); for women, no significant association was observed. Using a likelihood-ratio test, we found a statistically significant interaction between intervention group and sex (P = 0.03). CONCLUSION: The results of the current analyses indicate that men may experience more benefit from dietary fiber than do women and may help to explain some of the discrepant results reported in the literature.

Adenoma↗
PubMed2006

Associations of Ki-ras proto-oncogene mutation and p53 gene overexpression in sporadic colorectal adenomas with demographic and clinicopathologic characteristics.

In colorectal tumorigenesis, Ki-ras proto-oncogene mutation often occurs early in the adenoma-adenocarcinoma sequence, whereas mutation of the p53 gene is associated with late progression to carcinoma. We evaluated the relationship of demographic and clinicopathologic characteristics to Ki-ras mutation and p53 gene product overexpression in 1,093 baseline sporadic colorectal adenomas from 926 individuals enrolled in a phase III recurrence prevention trial. Ki-ras mutation was found in 14.7% of individuals and p53 overexpression was found in 7.0% of those tested. Multivariate analysis found older age, rectal location, and villous histology to be independently associated with Ki-ras mutation. Individuals with an advanced adenoma (>or=1 cm or high-grade dysplasia or villous histology) had a 4-fold higher likelihood of Ki-ras mutation [odds ratios (OR), 3.96; 95% confidence intervals (CI), 2.54-6.18]. Ki-ras mutations in codon 12 and of the G-to-A transition type were more frequent in older individuals, whereas G-to-T transversion was more frequent in rectal adenomas than in the colon. Multivariate analysis showed that previous history of a polyp (P = 0.03) was inversely associated with p53 overexpression. Large adenoma size (>or=1 cm), high-grade dysplasia, and villous histology were independently associated with p53 overexpression, with the strongest association for advanced adenomas (OR, 7.20; 95% CI, 3.01-17.22). Individuals with a Ki-ras mutated adenoma were more likely to overexpress p53 (OR, 2.46; 95% CI, 1.36-4.46), and 94.8% of adenomas with both alterations were classified as advanced (P <or= 0.0001). Our large cross-sectional study supports the role of both Ki-ras and p53 in the progression of adenomas and shows that their molecular pathogenesis differs by anatomic location, age, and mucosal predisposition as evidenced by previous history of a polyp.

Adenocarcinoma↗
PubMed2006

Effects of repeated green tea catechin administration on human cytochrome P450 activity.

PURPOSE: Preclinical studies suggested that green tea or green tea catechins can modulate the activities of drug-metabolizing enzymes. We conducted this clinical study to determine the effect of repeated green tea catechin administration on human cytochrome P450 (CYP) enzyme activities. METHODS: Forty-two healthy volunteers underwent a 4-week washout period by refraining from tea or tea-related products. At the end of the washout period, study participants received a cocktail of CYP metabolic probe drugs, including caffeine, dextromethorphan, losartan, and buspirone for assessing the activity of CYP1A2, CYP2D6, CYP2C9, and CYP3A4, respectively. Blood and urine samples before and 8 h after probe drug administration were collected to determine parent drug and metabolite concentrations for measurements of baseline CYP enzyme activities. Following the baseline evaluation, study participants underwent 4 weeks of green tea catechin intervention at a dose that contains 800 mg epigallocatechin gallate (EGCG) daily. The green tea catechin product was taken on an empty stomach to optimize the p.o. bioavailability of EGCG. The EGCG dose given in this study exceeded the amounts provided by average green tea consumption. Upon completion of the green tea catechin intervention, the postintervention CYP enzyme activities were evaluated as described above. RESULTS: There are large between-subject variations in CYP enzyme activities in healthy individuals. Four weeks of green tea catechin intervention did not alter the phenotypic indices of CYP1A2, CYP12D6, and CYP12C9, but resulted in a 20% increase (P = 0.01) in the area under the plasma buspirone concentration-time profile, suggesting a small reduction in CYP3A4 activity. CONCLUSIONS: We conclude that repeated green tea catechin administration is not likely to result in clinically significant effects on the disposition of drugs metabolized by CYP enzymes.

Administration, Oral↗
PubMed2006

Risk group, skin lesion history, and sun sensitivity reliability in squamous cell skin cancer progression.

In studies of skin cancer, participants are often classified into risk groups based on self-reported history of sun exposure or skin characteristics. We sought to determine the reliability of self-reported skin characteristics among participants of a study to evaluate markers for nonmelanoma skin cancer (NMSC). Multiple questionnaires and screening protocols were administered over a 3-month period to individuals from three risk groups: existing sun damage on forearms but no visible actinic keratoses (n = 91), visible actinic keratoses (n = 38), and history of resected squamous cell skin cancer in the last 12 months (n = 35). We assessed consistency of risk group assignment between telephone screen and study dermatologist assignment, self-reported sun sensitivity (telephone recruitment form versus participant completed profile), and self-reported history of NMSC skin lesions (telephone recruitment form versus health history). There was substantial agreement between probable risk group and final assignment (kappa = 0.76; 95% confidence interval, 0.65-0.85) and agreement did not differ by gender. Agreement for self-reported sun sensitivity was moderate (kappa weighted = 0.46; 95% confidence interval, 0.36-0.56) with higher agreement for women. For self-reported NMSC lesion history between two interviews, 24 days apart, kappa estimates ranged from 0.66 to 0.78 and were higher for women than men. Overall, there was evidence for substantial reproducibility related to risk group assignment and self-reported history of NMSC, with self-reported sun sensitivity being less reliable. In all comparisons, women had higher kappa values than men. These results suggest that self-reported measures of skin cancer risk are reasonably reliable for use in screening subjects into studies.

Adult↗
PubMed2005

MGMT promoter methylation and field defect in sporadic colorectal cancer.

BACKGROUND: Sporadic colorectal cancers often arise from a region of cells characterized by a "field defect" that has not been well defined molecularly. DNA methylation has been proposed as a candidate mediator of this field defect. The DNA repair gene O6-methylguanine-DNA methyltransferase (MGMT) is frequently methylated in colorectal cancer. We hypothesized that MGMT methylation could be one of the mediators of field cancerization in the colon mucosa. METHODS: We studied MGMT promoter methylation by three different bisulfite-based techniques in tumor, adjacent mucosa, and non-adjacent mucosa from 95 colorectal cancer patients and in colon mucosa from 33 subjects with no evidence of cancer. Statistical tests were two-sided. RESULTS: MGMT promoter methylation was present in 46% of the tumors. Patients whose cancer had MGMT promoter methylation also had substantial MGMT promoter methylation in apparently normal adjacent mucosa. This methylation was seen with a quantitative assay in 50% (22/44; 95% confidence interval [CI] = 34% to 65%) of normal samples with MGMT promoter methylation in the adjacent tumors, 6% (3/51; 95% CI = 1% to 16%) of samples without MGMT methylation in adjacent tumors, and 12% (4/33; 95% CI = 3% to 28%) of control samples (P < .001 for comparison between each of the latter two groups and the first group). MGMT methylation was detected with a more sensitive assay in 94%, 34%, and 27% of these samples, respectively (P < .001). In grossly normal colonic mucosa of colon cancer patients, methylation was detected 10 cm away from the tumor in 10 of 13 cases. Tumors with MGMT promoter methylation had a higher rate of G-to-A mutation in the KRAS oncogene than tumors without MGMT promoter methylation (10/42 versus 3/46, P = .03). Using a sensitive mutant allele-specific amplification assay for KRAS mutations, we also found KRAS mutations in 12% (3/25; 95% CI = 2.5% to 31%) of colorectal mucosas with detectable MGMT methylation and 3% (2/64; 95% CI = 0.4% to 11%) of colorectal mucosas without MGMT methylation (P = .13). CONCLUSION: Some colorectal cancers arise from a field defect defined by epigenetic inactivation of MGMT. Detection of this abnormality may ultimately be useful in risk assessment for colorectal cancer.

Biomarkers, Tumor↗
PubMed2005

Randomized trial of adjuvant intraperitoneal alpha-interferon in stage III ovarian cancer patients who have no evidence of disease after primary surgery and chemotherapy: An intergroup study.

OBJECTIVE: Despite the improvement in progression-free and overall survival in patients with advanced ovarian cancer associated with platinum-taxane chemotherapy, strategies are needed to prevent the greater than 70% recurrence rate. METHOD: The Southwest Oncology Group (SWOG) initiated a phase III intergroup trial of alpha-interferon (IFNalpha-26, Schering-Plough, Kenilworth, NJ) in weekly doses of 50 x 10(6) IU (for 6 doses) versus observation only in patients with no pathological evidence of residual disease at second-look surgery in 1988. RESULTS: Patient accrual was extremely slow and the trial was permanently closed in 1999 by the SWOG Data and Safety Monitoring Committee with 74 registered patients. Of these patients, 70 were evaluable for progression-free and overall survival. There was no significant difference between the two study arms in relation to median progression-free survival (P = 0.56). The median survival duration associated with intraperitoneal alpha-interferon had not been reached versus 87 months on the observation arm. In general, intraperitoneal alpha-interferon was well tolerated. There were no treatment-related deaths or grade 4 adverse events. Although no efficacy conclusions can be drawn from this prematurely closed trial, it should be noted that 57% of the patients on the observation arm recurred and all died, whereas 63% recurred and only 43% died on the intraperitoneal alpha-interferon arm. CONCLUSION: Although this was a negative study, there should continue to be interest in the use of biological therapy to improve survival of patients in complete remission following primary chemotherapy.

Adult↗
PubMed2005

Effects of dosing condition on the oral bioavailability of green tea catechins after single-dose administration of Polyphenon E in healthy individuals.

PURPOSE: Green tea has been shown to exhibit cancer-preventive activities in preclinical studies. Its consumption has been associated with decreased risk of certain types of cancers in humans. The oral bioavailability of the major green tea constituents, green tea catechins, is low, resulting in systemic catechin levels in humans many fold less than the effective concentrations determined in in vitro systems. We conducted this clinical study to test the hypothesis that the oral bioavailability of green tea catechins can be enhanced when consumed in the absence of food. EXPERIMENTAL DESIGNS: Thirty healthy volunteers were randomly assigned to one of the following doses of Polyphenon E (a decaffeinated and defined green tea catechin mixture): 400, 800, or 1,200 mg, based on the epigallocatechin gallate content (10 subjects per dose group). After an overnight fast, study participants took a single dose of Polyphenon E with or without a light breakfast, which consisted of one or two 4-oz muffins and a glass of water. Following a 1-week wash-out period, subjects were crossed over to take the same dose of Polyphenon E under the opposite fasting/fed condition. Tea catechin concentrations in plasma and urine samples collected after dosing were determined by high-pressure liquid chromatography analysis. RESULTS: Consistent with previous reports, epigallocatechin gallate and epicatechin gallate were present in plasma mostly as the free form, whereas epicatechin and epigallocatechin were mostly present as the glucuronide and sulfate conjugates. There was >3.5-fold increase in the average maximum plasma concentration of free epigallocatechin gallate when Polyphenon E was taken in the fasting condition than when taken with food. The dosing condition led to a similar change in plasma-free epigallocatechin and epicatechin gallate levels. Taking Polyphenon E in the fasting state did not have a significant effect on the plasma levels of total (free and conjugated) epigallocatechin, but resulted in lower plasma levels of total epicatechin. Urinary epigallocatechin gallate and epicatechin gallate levels were very low or undetectable following Polyphenon E administration with either dosing condition. Taking Polyphenon E under the fasting state resulted in a significant decrease in the urinary recovery of total epigallocatechin and epicatechin. Polyphenon E administered as a single dose over the dose range studied was generally well-tolerated by the study participants. Mild and transient nausea was noted in some of the study participants and was seen most often at the highest study agent dose (1,200 mg epigallocatechin gallate) and in the fasting condition. CONCLUSIONS: We conclude that greater oral bioavailability of free catechins can be achieved by taking the Polyphenon E capsules on an empty stomach after an overnight fast. Polyphenon E up to a dose that contains 800 mg epigallocatechin gallate is well-tolerated when taken under the fasting condition. This dosing condition is also expected to optimize the biological effects of tea catechins.

Abdominal Pain↗
PubMed2005

Phase III trial of ursodeoxycholic acid to prevent colorectal adenoma recurrence.

BACKGROUND: Ursodeoxycholic acid (UDCA) treatment is associated with a reduced incidence of colonic neoplasia in preclinical models and in patients with conditions associated with an increased risk for colon cancer. We conducted a phase III, double-blind placebo-controlled trial of UDCA to evaluate its ability to prevent colorectal adenoma recurrence. METHODS: We randomly assigned 1285 individuals who had undergone removal of a colorectal adenoma within the past 6 months to daily treatment with UDCA (8-10 mg/kg of body weight; 661 participants) or with placebo (624 participants) for 3 years or until follow-up colonoscopy. Recurrence rates (number of recurrent adenomas per unit time) were compared by use of a Huber-White variance estimator. Proportions of participants with one or more recurrent adenomas were compared with a Pearson chi-square statistic; adjusted odds ratios (ORs) were obtained by logistic regression. All statistical tests were two-sided. RESULTS: We observed a non-statistically significant 12% reduction in the adenoma recurrence rate associated with UDCA treatment, compared with placebo treatment. However, UDCA treatment was associated with a statistically significant reduction (P = .03) in the recurrence of adenomas with high-grade dysplasia (adjusted OR = 0.61, 95% confidence interval = 0.39 to 0.96). We observed no statistically significant differences between UDCA and placebo groups in recurrence with regard to adenoma size, villous histology, or location. CONCLUSIONS: UDCA treatment was associated with a non-statistically significant reduction in total colorectal adenoma recurrence but with a statistically significant 39% reduction in recurrence of adenomas with high-grade dysplasia. Because severely dysplastic lesions have a high risk of progression to invasive colorectal carcinoma, this finding indicates that future chemoprevention trials of UDCA in individuals with such lesions should be considered.

Adenoma↗