Sweat Production During Continuous and Interval Aerobic Exercise.

INTRODUCTION:Aerobic exercise within the habitable volume of small spacecraft needed for space exploration beyond low Earth orbit is expected to challenge the capacity of environmental control systems. Moisture control is a primary concern. Crewmembers will contribute moisture to the cabin environment in the form of sweat while exercising. The effects of continuous aerobic exercise for improving and maintaining aerobic capacity is well characterized. Likewise, evidence suggests that high intensity interval exercise for shorter durations is also effective in building and maintaining aerobic capacity.METHODS: On separate days, measures of sweat and respiratory responses were made for continuous (30 min of steady state exercise at ∼75% of aerobic capacity) and two interval (4 × 4 min, 8 × 30 s) exercise protocols.RESULTS: We observed that the 4-min and 30-s interval protocols produce 16% and 66% less metabolic water loss vs. the continuous exercise protocol, respectively. These responses were highly correlated with the amount of work performed (R² = 0.81) and the amount of energy expenditure (R² = 0.83) during exercise.DISCUSSION: These results suggest that interval exercise may be a useful alternative to continuous aerobic exercise when metabolic water production is an environmental concern. The results may inform the choices of aerobic exercise countermeasure protocols for use in deep space exploration.Ryder JW, Crowell JB, Song HJ, Ewert M. Sweat production during continuous and interval aerobic exercise. Aerosp Med Hum Perform. 2023; 94(8):623-628.

Association of clinical factors and recent anticancer therapy with COVID-19 severity among patients with cancer: a report from the COVID-19 and Cancer Consortium.

BACKGROUND: Patients with cancer may be at high risk of adverse outcomes from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We analyzed a cohort of patients with cancer and coronavirus 2019 (COVID-19) reported to the COVID-19 and Cancer Consortium (CCC19) to identify prognostic clinical factors, including laboratory measurements and anticancer therapies. PATIENTS AND METHODS: Patients with active or historical cancer and a laboratory-confirmed SARS-CoV-2 diagnosis recorded between 17 March and 18 November 2020 were included. The primary outcome was COVID-19 severity measured on an ordinal scale (uncomplicated, hospitalized, admitted to intensive care unit, mechanically ventilated, died within 30 days). Multivariable regression models included demographics, cancer status, anticancer therapy and timing, COVID-19-directed therapies, and laboratory measurements (among hospitalized patients). RESULTS: A total of 4966 patients were included (median age 66 years, 51% female, 50% non-Hispanic white); 2872 (58%) were hospitalized and 695 (14%) died; 61% had cancer that was present, diagnosed, or treated within the year prior to COVID-19 diagnosis. Older age, male sex, obesity, cardiovascular and pulmonary comorbidities, renal disease, diabetes mellitus, non-Hispanic black race, Hispanic ethnicity, worse Eastern Cooperative Oncology Group performance status, recent cytotoxic chemotherapy, and hematologic malignancy were associated with higher COVID-19 severity. Among hospitalized patients, low or high absolute lymphocyte count; high absolute neutrophil count; low platelet count; abnormal creatinine; troponin; lactate dehydrogenase; and C-reactive protein were associated with higher COVID-19 severity. Patients diagnosed early in the COVID-19 pandemic (January-April 2020) had worse outcomes than those diagnosed later. Specific anticancer therapies (e.g. R-CHOP, platinum combined with etoposide, and DNA methyltransferase inhibitors) were associated with high 30-day all-cause mortality. CONCLUSIONS: Clinical factors (e.g. older age, hematological malignancy, recent chemotherapy) and laboratory measurements were associated with poor outcomes among patients with cancer and COVID-19. Although further studies are needed, caution may be required in utilizing particular anticancer therapies. CLINICAL TRIAL IDENTIFIER: NCT04354701.

A novel approach for establishing fitness standards for occupational task performance.

PURPOSE: To identify strength and performance thresholds below which task performance is impaired. METHODS: A new weighted suit system was used to manipulate strength-to-body-weight ratio during the performance of simulated space explorations tasks. Statistical models were used to evaluate various measures of muscle strength and performance on their ability to predict the probability that subjects could complete the tasks in an acceptable amount of time. Thresholds were defined as the point of greatest change in probability per change in the predictor variable. For each task, median time was used to define the boundary between "acceptable" and "unacceptable" completion times. RESULTS: Fitness thresholds for four space explorations tasks were identified using 23 physiological input variables. Area under receiver operator characteristic curves varied from a low of 0.68 to a high of 0.92. CONCLUSION: An experimental analog for altering strength-to-body weight combined with a probability-based statistical model for success was suitable for identifying thresholds for task performance below which tasks could either not be completed or time to completion was unacceptably high. These results provide data for strength recommendations for exploration mission ambulatory task performance. Furthermore, the approach can be used to identify thresholds for other areas where occupationally relevant tasks vary considerably.

Preliminary evidence for neural responsiveness to infants in mothers with schizophrenia and the implications for healthy parenting.

Schizophrenia is a severe mental illness that may significantly affect maternal sensitive behaviour. Neural correlates of maternal behaviour represent a potentially valuable means of differentiating objectively between healthy mothers expressing variations in maternal sensitivity. As mothers with schizophrenia (MWS) show deficits in behavioural responses to infants compared to healthy mothers, we explored whether maternal brain responses to infant stimuli would be significantly reduced in MWS. We also examined whether differences in maternal behaviour between healthy and ill mothers (during play interactions with own infant) were associated with differences in brain activation to infant stimuli. We found no evidence of differential 'maternal brain' responses or 'maternal behavioural' responses in 11 new MWS compared to 20 healthy new mums; neither were neural responses to infants linked to behavioural or cognitive aspects of the mother's relationship with her infant in MWS. These preliminary findings suggest maternal sensitivity differences between MWS and healthy mothers, suggested in previous studies, may be reversible in stable treated MWS.

Isometric Midthigh Pull Reliability and Relationship to Deadlift One Repetition Maximum.

De Witt, JK, English, KL, Crowell, JB, Kalogera, KL, Guilliams, ME, Nieschwitz, BE, Hanson, AM, and Ploutz-Snyder, LL. Isometric midthigh pull reliability and relationship to deadlift one repetition maximum. J Strength Cond Res 32(2): 528-533, 2018-The purpose of this investigation was to examine the reliability of the isometric midthigh pull (IMTP) and the relationship between IMTP peak force and deadlift 1 repetition maximum (1RM). Nine subjects (5 men and 4 women; 40.6 ± 8.0 years; 1.72 ± 0.10 m; 75.6 ± 13.4 kg) participated in this study. Isometric midthigh pull and deadlift 1RM were both performed during 2 testing sessions. For IMTP, peak force and peak rate of force development (RFD) were determined, in addition to RFD at 30 ms, 50 ms, 90 ms, 150 ms, 200 ms, and 250 ms after initiation of the pull. Intraclass correlation coefficients (ICCs) were calculated to evaluate the reliability of IMTP measures. Pearson product-moment correlations and linear regression were used to determine associations between IMTP and deadlift 1RM. Isometric midthigh pull peak force was reproducible both within (ICC = 0.98 and 0.97) and between sessions (ICC = 0.89) and significantly correlated with deadlift 1RM (r = 0.88, p ≤ 0.05), but intermediate force outputs and RFD were not. Lack of associations between RFD and deadlift 1RM indicate that the ability to create explosive force may be independent of the ability to create maximal force. The strong relationship between IMTP peak force and deadlift 1RM was present regardless of which IMTP repetition across the 2 sessions was examined. Peak force generated during IMTP is a reliable method to assess full body maximal strength. A single IMTP repetition, provided adequate familiarization and warm-up, correlates strongly with deadlift 1RM. Practitioners can use the IMTP test as a method to estimate maximal deadlift strength in a quick and potentially less provocative manner than traditional 1RM testing.

Virtual street-crossing performance in persons with multiple sclerosis: Feasibility and task performance characteristics.

OBJECTIVES: Multiple sclerosis (MS) is a neurological disease that commonly results in physical and cognitive dysfunction. Accordingly, MS might impact the ability to safely cross the street. The purpose of this study was to examine the feasibility of a simulated street-crossing task in persons with MS and to determine differences in street-crossing performance between persons with MS and non-MS controls. METHODS: 26 participants with MS (median Expanded Disability Status Scale [EDSS] score = 3.5) and 19 controls completed 40 trials of a virtual street-crossing task. There were 2 crossing conditions (i.e., no distraction and phone conversation), and participants performed 20 trials per condition. Participants were instructed that the goal of the task was to cross the street successfully (i.e., without being hit be a vehicle). The primary outcome was task feasibility, assessed as completion and adverse events. Secondary outcomes were measures of street-crossing performance. RESULTS: Overall, the simulated street-crossing task was feasible (i.e., 90% completion, no adverse events) in participants with MS. Participants with MS waited longer and were less attentive to traffic before entering the street compared with controls (all P < .05). Participants with MS also took longer to cross the street and were closer to oncoming vehicles when exiting the street compared to controls (all P < .05). When distracted, all participants took longer to initiate crossing, took longer to cross the street, and made more head turns while crossing (all P < .05). There were no significant group by condition interaction effects (all P > .05). CONCLUSIONS: A virtual street-crossing task is feasible for studying street-crossing behavior in persons with mild MS and most individuals with moderate MS. Virtual street-crossing performance is impaired in persons with MS compared to controls; however, persons with MS do not appear to be more vulnerable to a distracting condition. The virtual reality environment presents a safe and useful setting for understanding pedestrian behavior in persons with MS.

Posttraumatic stress disorder, alone or additively with early life adversity, is associated with obesity and cardiometabolic risk.

BACKGROUND AND AIMS: There is some evidence that posttraumatic stress disorder (PTSD) and early life adversity may influence metabolic outcomes such as obesity, diabetes, and cardiovascular disease. However, whether and how these interact is not clear. METHODS: We analyzed data from a cross-sectional and longitudinal study to determine how PTSD severity influences obesity, insulin sensitivity, and key measures and biomarkers of cardiovascular risk. We then looked at how PTSD and early life adversity may interact to impact these same outcomes. RESULTS: PTSD severity is associated with increasing risk of obesity, diabetes, and cardiovascular disease, with higher symptoms correlating with higher values of BMI, leptin, fibrinogen, and blood pressure, and lower values of insulin sensitivity. PTSD and early life adversity have an additive effect on these metabolic outcomes. The longitudinal study confirmed findings from the cross sectional study and showed that fat mass, leptin, CRP, sICAM-1, and sTNFRII were significantly increased with higher PTSD severity during a 2.5 year follow-up period. CONCLUSIONS: Individuals with early life adversity and PTSD are at high risk and should be monitored carefully for obesity, insulin resistance, and cardiometabolic risk.

Subchronic oral toxicity and cardiovascular safety pharmacology studies of resveratrol, a naturally occurring polyphenol with cancer preventive activity.

To characterize the subchronic oral toxicity of resveratrol, CD rats received daily gavage doses of 0, 200, 400, or 1000 mg resveratrol/kg/day, and beagle dogs received daily capsule doses of 0, 200, 600, or 1200 mg resveratrol/kg/day for 90 days. Resveratrol induced only minimal toxicity, consisting of dose-related reductions in body weight gain in female rats and both sexes of dogs, and a statistically significant increase in bilirubin levels in rats at the 1000 mg/kg/day dose. Clinical observations, hematology, ophthalmology, neurotoxicity evaluations (functional observational batteries), organ weights, and gross pathology provided no biologically significant evidence of resveratrol toxicity in either species. In rats, the high dose of resveratrol reduced the incidence of cardiomyopathy; no other microscopic changes were seen. Histopathologic changes in dogs were limited to minimal inflammatory infiltrates in the kidney and urinary bladder, which were not considered toxicologically significant. A cardiovascular safety pharmacology (telemetry) study in dogs revealed no evidence of resveratrol toxicity. Based on body weight effects, the No Observed Adverse Effect Level (NOAEL) for resveratrol was 200mg/kg/day in rats and 600 mg/kg/day in dogs. The apparent cardioprotective activity of resveratrol in rats demonstrates that its potentially beneficial activities may extend beyond efficacy in cancer prevention.

Exposure and toxicity of green tea polyphenols in fasted and non-fasted dogs.

Standardized green tea extract was evaluated for exposure and toxicity in Beagle dogs following oral dosing by capsules. The main component (-)-epigallocatechin gallate (EGCG) accounted for 56-72% of the material. A 9-month chronic study (0, 200, 500, and 1000 mg/kg/day) was done in fasted dogs to take advantage of the reported improved catechin bioavailability with fasting. Extensive morbidity, mortality, and pathology of many major organs led to its early termination at 6.5 months and prevented identification of the toxicity mechanisms. A follow-up 13-week study examined the exposure to and toxicity of the extract. In general, toxicities were less severe than in the chronic study during the same interval. Dosing in a fed state resulted in considerably lower and less variable exposure than found under fasted conditions. Toxicity was less frequent and of lesser severity with lower exposure but limited sample size and large variability prevented reaching that definitive conclusion. Differences in mortality and morbidity between the preliminary terminated chronic and follow-up subchronic studies with the same dose of the same drug lot and similar exposure were not fully resolved as there may be other as yet unclear confounding factors.

Subchronic oral toxicity studies of Se-methylselenocysteine, an organoselenium compound for breast cancer prevention.

Se-methylselenocysteine (MSC) is an organoselenium compound being developed for breast cancer chemoprevention. To characterize MSC toxicity, CD rats received daily gavage doses of 0, 0.5, 1.0, or 2.0 mg/kg/day (0, 3, 6, or 12 mg/m(2)/day), and beagle dogs received daily gavage doses of 0, 0.15, 0.3, or 0.6 mg/kg/day (0, 3, 6, or 12 mg/m(2)/day) for 28 days. In rats, MSC induced dose-related hepatomegaly in both sexes; mild anemia, thrombocytopenia, and elevated liver enzymes were observed in high dose females only. Microscopic pathology included hepatocellular degeneration (high dose males, all doses in females); arrested spermatogenesis (high dose males); and atrophy of corpora lutea (middle and high dose females). In dogs, MSC induced mild anemia in middle and high dose males, and in high dose females. Toxicologically significant microscopic lesions in dogs were seen only in the liver (peliosis and vacuolar degeneration in high dose males, midzonal necrosis in males in all dose groups). Based on liver pathology seen in female rats in all dose groups, the no observed adverse effect level (NOAEL) for MSC in rats is <0.5mg/kg/day. Based on alterations in hematology parameters and liver morphology in male dogs in all dose groups, the NOAEL for MSC in dogs is <0.15 mg/kg/day.

Oncogenicity evaluation of resveratrol in p53(+/-) (p53 knockout) mice.

A six-month study was conducted in p53(+/-) mice to evaluate the possible oncogenicity of resveratrol (3,5,4'-trihydroxy-trans-stilbene), a cancer chemopreventive agent present in grapes and other foods. p53(+/-) mice (25/sex/group) received daily gavage exposure to vehicle only (negative control), resveratrol doses of 1000, 2000, or 4000 mg/kg/day, or p-cresidine (400 mg/kg/day; positive control). No mortality was seen in mice receiving the low dose of resveratrol. However, the mid and high doses induced mortality associated with impaction of the test article in the gastrointestinal tract. Resveratrol had no effect on body weight, food consumption, or clinical signs in surviving mice in any dose group, but induced dose-related increases in liver weight and serum cholesterol in both sexes. Mild anemia was seen in male mice at the high dose only; hematologic effects were not seen in females. Histopathology identified the kidney (hydronephrosis) and urinary bladder (epithelial hyperplasia) as target tissues for resveratrol toxicity. The incidences of both benign and malignant tumors in mice exposed to resveratrol were comparable to those in vehicle controls. By contrast, the positive control article, p-cresidine, induced urinary bladder cancer in both sexes. When administered to p53(+/-) mice at its maximum tolerated dose, resveratrol demonstrates no evidence of oncogenicity.

Genotoxicity and carcinogenicity studies of soy isoflavones.

The potential cancer preventive efficacy of soy isoflavones is being investigated in preclinical and phase 1 clinical studies sponsored by the U.S. National Cancer Institute. Although 90-day oral toxicity studies with PTI G-2535 (an investigational soy isoflavone drug product) in rats and dogs, as well as teratology studies, indicated no signs of toxicity, there remains a mechanistic concern associated with the ability of isoflavones (i.e., genistein) to inhibit topoisomerase, possibly leading to DNA strand breaks. The present report describes results from two in vitro genotoxicity studies, one in vivo genotoxicity study, and a single carcinogenicity study conducted in p53 knockout mice. Bacterial mutagenesis experiments using six tester strains without metabolic activation revealed no evidence that PTI G-2535 was mutagenic. In similar experiments with exogenous metabolic activation there were statistically significant increases in revertants, but less than twofold, in a single (Salmonella typhimurium TA100) tester strain. Mouse lymphoma cell mutagenesis experiments conducted with and without metabolic activation revealed statistically significant increases in mutation frequency at PTI G-2535 concentrations > or = 0.8 and 12 microg/ml, respectively; such increases were dose related and increases in the frequency of both small and large colonies were observed. A statistically significant increase in the frequency of micronucleated polychromatic erythrocytes was also seen 24 hours after treatment in male, but not female, mice who received 500 and 1000 mg/kg body weight PTI G-2535; however,such increases were small, were not dose related, and were not observed 48 hours after treatment. In contrast, dietary genistein had no effect on survival, weight gain, or the incidence or types of tumors that developed in cancer-prone rodents lacking the p53 tumor suppressor gene, p53 knockout mice. The apparent risk/benefit of isoflavone ingestion may ultimately depend on the dose and developmental timing of exposure.

High-performance liquid chromatography-based determination of total isothiocyanate levels in human plasma: application to studies with 2-phenethyl isothiocyanate.

Dietary and pharmacologic isothiocyanates (ITCs) may play a role in reducing the risk of certain cancers. The quantification of ITCs in humans is important both for epidemiological and pharmacokinetic studies. We describe a modification of an HPLC-based assay of urinary ITCs for use with human plasma. The assay utilizes the cyclocondensation reaction of 1,2-benzenedithiol with ITCs present in human plasma, followed by a two-step hexane extraction and analysis by HPLC using UV detection at 365 nm. The method shows linearity and reproducibility with human plasma over a range of 49-3003 nM phenethyl isothiocyanate (PEITC) (r(2) = 0.996 +/- 0.003). A similar degree of linearity was seen with two other biologically occurring conjugates of PEITC: PEITC--N-acetylcysteine (PEITC--NAC) and PEITC--glutathione (PEITC--GSH). The recovery of PEITC assessed on multiple days was 96.6 +/- 1.5% and was 100% for PEITC--GSH and PEITC--NAC. The reproducibility of the assay on multiday samplings showed a mean %CV of 6.5 +/- 0.3% for PEITC, 6.4 +/- 4.3 for PEITC--NAC and 12.3 +/- 3.9 for PEITC--GSH. In clinical studies, mean plasma ITC level of 413 +/- 193 nM PEITC equivalents was determined for a non-dietary-controlled group of 23 subjects. Multiday analysis data from pharmacokinetic plasma sets of 3 subjects taking a single dose of PEITC at 40 mg showed a good CV (range: 16-21%). The applicability of the methodology to pharmacokinetic studies of PEITC in humans is demonstrated.

Desorption/ionization on silicon (DIOS): a diverse mass spectrometry platform for protein characterization.

Since the advent of matrix-assisted laser desorption/ionization and electrospray ionization, mass spectrometry has played an increasingly important role in protein functional characterization, identification, and structural analysis. Expanding this role, desorption/ionization on silicon (DIOS) is a new approach that allows for the analysis of proteins and related small molecules. Despite the absence of matrix, DIOS-MS yields little or no fragmentation and is relatively tolerant of moderate amounts of contaminants commonly found in biological samples. Here, functional assays were performed on an esterase, a glycosidase, a lipase, as well as exo- and endoproteases by using enzyme-specific substrates. Enzyme activity also was monitored in the presence of inhibitors, successfully demonstrating the ability of DIOS to be used as an inhibitor screen. Because DIOS is a matrix-free desorption technique, it also can be used as a platform for multiple analyses to be performed on the same protein. This unique advantage was demonstrated with acetylcholine esterase for qualitative and quantitative characterization and also by its subsequent identification directly from the DIOS platform.

Oltipraz concentrations in plasma, buccal mucosa cells, and lipids: pharmacological studies.

Oltipraz is considered one of the most potent cancer chemoprevention agents, as shown in preclinical studies. Its pharmacological effects in humans have been associated with unusual toxicity affecting the fingers and toes. This study was designed to test intermittent dosing schedules using two dosage levels: 500 mg as a single weekly dose and 200 mg as a biweekly dose, each for 30 days. Fifteen men and women were studied in each dosing group. All were heavy smokers considered to be at high risk for developing lung cancer. Plasma, buccal mucosa cell, and lipoprotein concentrations were measured at different intervals corresponding to the time period when most of the adverse effects occur. No serious toxicities were observed using these doses and schedules. The plasma and buccal mucosa cell concentrations of Oltipraz showed substantial interindividual variations at each sampling. Some subjects had no detectable plasma or buccal mucosal cell Oltipraz concentrations. The distribution of Oltipraz incorporation into the lipid fractions and albumin was changed by the administration of different schedules of Oltipraz. The results of this study suggest that the intermittent dosing is well tolerated and does not result in steady state in plasma or buccal mucosa cells. The variation and lack of detectable Oltipraz concentration in plasma, buccal mucosa cells, and lipids may affect both the toxicity and the pharmacological effects when these doses and schedules are used.

Agents, biomarkers, and cohorts for chemopreventive agent development in prostate cancer.

Chemoprevention is the use of agents to slow progression of, reverse, or inhibit carcinogenesis thereby lowering the risk of developing invasive or clinically significant disease. With its long latency, high incidence and significant morbidity and mortality, prostate cancer is a relevant target for chemoprevention. Developing rational chemopreventive strategies for prostate cancer requires well-characterized agents, suitable cohorts, and reliable intermediate biomarkers of cancer. Chemopreventive agent requirements are experimental or epidemiologic data showing efficacy, safety on chronic administration, and a mechanistic rationale for activity. Current promising agents include antiandrogens and antiestrogens; steroid aromatase inhibitors; retinoids and their modulators; 5alpha-reductase inhibitors; vitamins D, E, and analogs; selenium compounds; carotenoids; soy isoflavones; dehydroepiandrostenedione and analogs; 2-difluoromethylornithine; lipoxygenase inhibitors; apoptosis inducers; and nonsteroidal anti-inflammatory drugs. Identifying biomarkers and validating them as surrogate endpoints for cancer incidence are critical for prostate chemoprevention trials. Potentially useful biomarkers for prostate chemoprevention are associated with histologic, proliferative, differentiation-related, biochemical, and genetic/regulatory features of prostatic disease. In that the prostate is not easily visualized, critical issues also include adequacy and consistency of tissue sampling. Various drugs for the chemoprevention of prostate cancer are now under evaluation in phase 1, 2, and 3 clinical trials. Cohort selection should be based on various patient characteristics (stage of the disease, previous cancers or premalignant lesions, or high risk factors) and should be conducted within the context of standard treatment.

Porous silicon as a versatile platform for laser desorption/ionization mass spectrometry.

Desorption/ionization on porous silicon mass spectrometry (DIOS-MS) is a novel method for generating and analyzing gas-phase ions that employs direct laser vaporization. The structure and physicochemical properties of the porous silicon surfaces are crucial to DIOS-MS performance and are controlled by the selection of silicon and the electrochemical etching conditions. Porous silicon generation and DIOS signals were examined as a function of silicon crystal orientation, resistivity, etching solution, etching current density, etching time, and irradiation. Pre-and postetching conditions were also examined for their effect on DIOS signal as were chemical modifications to examine stability with respect to surface oxidation. Pore size and other physical characteristics were examined by scanning electron microscopy and Fourier transform infrared spectroscopy, and correlated with DIOS-MS signal. Porous silicon surfaces optimized for DIOS response were examined for their applicability to quantitative analysis, organic reaction monitoring, post-source decay mass spectrometry, and chromatography.

Surrogate end-point biomarkers in chemopreventive drug development.

Relevant and feasible surrogate end-points are needed for the evaluation of intervention strategies against cancer and other chronic, life-threatening diseases. Carcinogenesis can be viewed as a process of progressive disorganization. This process is characterized by the accumulation of genotypic lesions and corresponding tissue and cellular abnormalities, including loss of proliferation and apoptosis controls. Potential surrogate end-points for cancer incidence include both phenotypic and genotypic biomarkers of this progression. In the US National Cancer Institute chemoprevention programme, histological modulation of a precancer (intraepithelial neoplasia) has so far been the primary phenotypic surrogate end-point in chemoprevention trials. Additionally, high priority has been given to biomarkers measuring specific and general genotypic changes correlated with the carcinogenesis progression model for the targeted cancer (e.g., progressive genomic instability as measured by loss of heterozygosity or amplification at specific microsatellite loci). Other potential surrogate end-points include proliferation and differentiation indices, specific gene and general chromosome damage, cell growth regulatory molecules, and biochemical activities (e.g., enzyme inhibition). Serum biomarkers thought to be associated with cancer progression (e.g., prostate-specific antigen) are particularly appealing surrogate end-points because of accessibility. Potentially chemopreventive effects of the test agent may also be measured (e.g., tissue and serum estrogen levels in studies of steroid aromatase inhibitors). To establish chemopreventive efficacy, prevention of virtually all biomarker lesions, or of those lesions with particular propensity for progression, may be required. Ideally, the phenotype and genotype of any new or remaining precancers in the target tissue of chemopreventive agent-treated subjects would show less, and certainly no greater, potential for progression than those of placebo-treated subjects.

Phase I pharmacokinetic study of tea polyphenols following single-dose administration of epigallocatechin gallate and polyphenon E.

Green tea has been shown to exhibit cancer-preventive activities in preclinical studies. Its principal active components include epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin (EC), and epicatechin gallate, of which EGCG is the most abundant and possesses the most potent antioxidative activity. We performed a Phase I pharmacokinetic study to determine the systemic availability of green tea catechins after single oral dose administration of EGCG and Polyphenon E (decaffeinated green tea catechin mixture). Twenty healthy subjects (five subjects/dose level) were randomly assigned to one of the dose levels (200, 400, 600, and 800 mg based on EGCG content). All subjects were randomly crossed-over to receive the two catechin formulations at the same dose level. Blood and urine samples were collected for up to 24 h after oral administration of the study medication. Tea catechin concentrations in plasma and urine samples were determined using high-performance liquid chromatography with the coulometric electrode array detection system. After EGCG versus Polyphenon E administration, the mean area under the plasma concentration-time curves (AUC) of unchanged EGCG were 22.5 versus 21.9, 35.4 versus 52.2, 101.9 versus 79.7, and 167.1 versus 161.4 min x microg/ml at the 200-, 400-, 600-, and 800-mg dose levels, respectively. EGC and EC were not detected in plasma after EGCG administration and were present at low/undetectable levels after Polyphenon E administration. High concentrations of EGC and EC glucuronide/sulfate conjugates were found in plasma and urine samples after Polyphenon E administration. There were no significant differences in the pharmacokinetic characteristics of EGCG between the two study medications. The AUC and maximum plasma concentration (Cmax) of EGCG after the 800-mg dose of EGCG were found to be significantly higher than those after the 200- and 400-mg dose. The AUC and Cmax of EGCG after the 800-mg dose of Polyphenon E were significantly higher than those after the three lower doses. We conclude that the two catechin formulations resulted in similar plasma EGCG levels. EGC and EC were present in the body after the Polyphenon E administration; however, they were present predominantly in conjugated forms. The systemic availability of EGCG increased at higher doses, possibly due to saturable presystemic elimination of orally administered green tea polyphenols.