Genetic and molecular markers of urothelial premalignancy and malignancy

The molecular genetic changes reported in bladder tumors can be classified as primary and secondary aberrations. Primary molecular alterations may be defined as those directly related to the genesis of cancer. These are frequently found as the sole abnormality and are often associated with particular tumors. There are characteristic primary abnormalities involved in th production of low-grade/well-differentiated neoplasms, which destabilize cellular proliferation but have little effect on cellula "social" interactions or differentiation, as well as the rate of cell death or apoptosis. Other molecular events lead to high-grad neoplasms which disrupt growth control, including the cell cycle and apoptosis, and which have a major impact on biological behavior. A primary target leading to low-grade papillary superficial bladder tumors resides on chromosome 9, while p53 gene alterations are commonly seen in flat carcinoma in situ. Other molecular alterations must be elucidated, as many non-invasive neoplasms have neither chromosome 9 nor p53 alterations. Novel approaches utilizing tissue microdissection techniques an molecular genetic assays are needed to shed further light on this subject. Secondary genetic or epigenetic abnormalities may be fortuitous, or may determine the biological behavior of the tumor. Multiple molecular abnormalities are identified in most human cancers studied, including bladder neoplasms. The accumulation, rather than the order, of these genetic alterations may be the critical factor that grants synergistic activity. In this regard, it is noteworthy that many of the genes that are altered act upon the two recognized critical growth and senescenc pathways, TP53 and RB. These particular molecular aberrations may be especially important to evaluate for their use in the management of bladder cancer because of their commonality in progressive forms of the disease. Thus, clinical trials are underway to explore their use in specific situations, particularly in the surgical management of locally advanced disease, and to determine whether adjuvant chemotherapy in such patients may be of benefit. The use of molecular alterations in the management of non-invasive bladder neoplasms remains to be firmly established. Our knowledge of molecular alterations important in bladder cancer progression is far from complete, and further study is necessary to further elucidate cruci pathways involved in progression and therapeutic response. As per preneoplastic conditions, difficulties in identifying and interpreting the significance of phenotypic changes have imposed certain limitations, as has an evolving nomenclature and issues of reproducibility in interpreting morphologica criteria. Nevertheless, molecular alterations involving chromosome 9q and the INK4A locus in papillary superficial tumors vs changes in chromosomes 14q and 8q, p53 and RB in flat carcinoma in situ lesions may indicate a molecular basis for early events that lead to varying pathways in urothelial tumorigenesis. Studies aimed at revealing the clinical relevance of genet instability, as well as molecular or epigenetic alterations, in urothelium and preneoplastic lesions of otherwise morphologicall normal appearance are needed to further advance knowledge in the field. Clinical advances in bladder cancer will be facilitated by novel animal models paralleling the human disease. Molecular diagnostics, particularly specific antigen expression, fluorescence in situ hybridization and microsatellite analyses, have show great promise as screening and follow-up methodologies, and may supplement urine cytology in the diagnosis and characterization of new and recurrent disease. In addition, the use of high-throughput genomic/proteomic assays, linked to comprehensive databases, and coupled with robust bioinformatics will be key elements in elucidating the components of regulatory and signaling pathways involved in bladder tumorigenesis and cancer progression.     

cGMP binding sites on photoreceptor phosphodiesterase: role in feedback regulation of visual transduction.

A central step in vertebrate visual transduction is the rapid drop in cGMP levels that causes cGMP-gated ion channels in the photoreceptor cell membrane to close. It has long been a puzzle that the cGMP phosphodiesterase (PDE) whose activation causes this decrease contains not only catalytic sites for cGMP hydrolysis but also noncatalytic cGMP binding sites. Recent work has shown that occupancy of these noncatalytic sites slows the rate of PDE inactivation. We report here that PDE activation induced by activated transduction lowers the cGMP binding affinity for noncatalytic sites on PDE and accelerates the dissociation of cGMP from these sites. These sites can exist in three states: high affinity (Kd = 60 nM) for the nonactivated PDE, intermediate affinity (Kd approximately 180 nM) when the enzyme is activated in a complex with transducin, and low affinity (Kd > 1 microM) when transducin physically removes the inhibitory subunits of PDE from the PDE catalytic subunits. Activation of PDE by transducin causes a 10-fold increase in the rate of cGMP dissociation from one of the two noncatalytic sites; physical removal of the inhibitory subunits from the PDE catalytic subunits further accelerates the cGMP dissociation rate from both sites > 50-fold. Because PDE molecules lacking bound cGMP inactivate more rapidly, this suggests that a prolonged cGMP decrease may act as a negative feedback regulator to generate the faster, smaller photoresponses characteristic of light-adapted photoreceptors.     

Low vitamin D level is not associated with increased incidence of rheumatoid arthritis

To evaluate the association of vitamin D level with incident rheumatoid arthritis (RA) in a patient population using electronic health records (EHR). Case–control study with data extracted from EHR from 1/1/2001 to 12/31/2012 in the Geisinger Health System (GHS). Incident RA was defined as International Classification of Disease-9 code 714.0 twice by a GHS rheumatologist. Patients were identified at time of RA diagnoses and were matched 1:5 for age and gender with non-RA controls. Vitamin D levels were identified and extracted prior to RA diagnosis. The subjects were followed retrospectively with regard to their vitamin D levels; the most recent value of vitamin D prior to the RA diagnosis was used in the analysis. Vitamin D levels were treated both as continuous and categorical with two different cutoff values, 30 and 20 ng/ml. The association between vitamin D and RA was presented as the odds ratios with 95 % confidence intervals (OR, 95 % CI) from a conditional logistic regression model adjusting for obesity and smoking status. A total of 270 patients with incident RA and 1,341 matched controls were identified. The RA patients were 83.3 % female with median age at RA diagnosis of 62 years. The adjusted OR (95 % CI) for the association of vitamin D levels with incident RA compared with controls was 1.00 (0.99, 1.01), 0.98 (0.75, 1.29) and 1.12 (0.80, 1.57) for continuous, <30 and <20 ng/ml vitamin D levels, respectively. Subgroup analysis according to gender or rheumatoid factor positivity yielded similar results. In this patient population, vitamin D levels were not associated with the development of RA.     

A Framework for the Next Generation of Risk Science

Objectives: In 2011, the U.S. Environmental Protection Agency initiated the NexGen project to develop a new paradigm for the next generation of risk science.Methods: The NexGen framework was built on three cornerstones: the availability of new data on toxicity pathways made possible by fundamental advances in basic biology and toxicological science, the incorporation of a population health perspective that recognizes that most adverse health outcomes involve multiple determinants, and a renewed focus on new risk assessment methodologies designed to better inform risk management decision making.Results: The NexGen framework has three phases. Phase I (objectives) focuses on problem formulation and scoping, taking into account the risk context and the range of available risk management decision-making options. Phase II (risk assessment) seeks to identify critical toxicity pathway perturbations using new toxicity testing tools and technologies, and to better characterize risks and uncertainties using advanced risk assessment methodologies. Phase III (risk management) involves the development of evidence-based population health risk management strategies of a regulatory, economic, advisory, community-based, or technological nature, using sound principles of risk management decision making.Conclusions: Analysis of a series of case study prototypes indicated that many aspects of the NexGen framework are already beginning to be adopted in practice.Citation: Krewski D, Westphal M, Andersen ME, Paoli GM, Chiu WA, Al-Zoughool M, Croteau MC, Burgoon LD, Cote I. 2014. A framework for the next generation of risk science. Environ Health Perspect 122:796–805; http://dx.doi.org/10.1289/ehp.1307260     

Association between Dietary Nitrate,Nitrite Intake,and Site-Specific Cancer Risk: A Systematic Review and Meta-Analysis

Background: People consume nitrates, nitrites, nitrosamines, and NOCs compounds primarily through processed food. Many studies have yielded inconclusive results regarding the association between cancer and dietary intakes of nitrates and nitrites. This study aimed to quantify these associations across the reported literature thus far. Methods: We performed a systematic review following PRISMA and MOOSE guidelines. A literature search was performed using Web of Science, Embase, PubMed, the Cochrane library, and google scholar up to January 2020. STATA version 12.0 was used to conduct meta-regression and a two-stage meta-analysis. Results: A total of 41 articles with 13 different cancer sites were used for analysis. Of these 13 cancer types/sites, meta-regression analysis showed that bladder and stomach cancer risk was greater, and that pancreatic cancer risk was lower with increasing nitrite intakes. Kidney and bladder cancer risk were both lower with increasing nitrate intakes. When comparing highest to lowest (reference) categories of intake, meta-analysis of studies showed that high nitrate intake was associated with an increased risk of thyroid cancer (OR = 1.40, 95% CI: 1.02, 1.77). When pooling all intake categories and comparing against the lowest (reference) category, higher nitrite intake was associated with an increased risk of glioma (OR = 1.12, 95% CI: 1.03, 1.22). No other associations between cancer risk and dietary intakes of nitrates or nitrites were observed. Conclusion: This study showed varied associations between site-specific cancer risks and dietary intakes of nitrate and nitrite. Glioma, bladder, and stomach cancer risks were higher and pancreatic cancer risk was lower with higher nitrite intakes, and thyroid cancer risk was higher and kidney cancer risk lower with higher nitrate intakes. These data suggest type- and site-specific effects of cancer risk, including protective effects, from dietary intakes of nitrate and nitrite.     

Treatment of chronic woodchuck hepatitis virus infection in the Eastern woodchuck (Marmota monax) with nucleoside analogues is predictive of therapy for chronic hepatitis B virus infection in humans

The woodchuck hepatitis virus (WHV) and its natural host, the Eastern woodchuck (Marmota monax), have been established as a model of hepatitis B virus (HBV)-induced disease. Several published studies have used this experimental animal model system to demonstrate potential antiviral therapies for chronic HBV infections. However, there has been little comparative information available on compounds used in clinical anti-HBV studies in WHV-infected woodchucks, thereby making interpretations of the potential relative effectiveness of new antiviral agents in humans more difficult. In this report, using a series of placebo-controlled studies, we compared the relative effectiveness of several nucleoside analogues that have been used in clinical trials for the treatment of chronic HBV infection against WHV replication in chronically infected woodchucks. Adenine-5'-arabinoside monophosphate (Ara-AMP [vidarabine]), ribavirin, (-)beta-L-2',3'-dideoxy-3'-thiacytidine (3TC [lamivudine]), and famciclovir (oral prodrug of penciclovir) induced depressions in viremia and intrahepatic WHV-DNA replication that were consistent with their relative effectiveness in anti-HBV human clinical trials. As observed in HBV-infected patients, 3' azido-3'-deoxythymidine (AZT [zidovudine]) had no effect on WHV replication in these studies. These experimental results more firmly establish chronic WHV infection in woodchucks as an accurate and predictive model for antiviral therapies against chronic HBV infection in humans and provide a baseline for comparative antiviral effects of other experimental antiviral agents in the WHV/woodchuck model system.     

Effect of sleep on regional blood flow distribution in piglets

The regional distribution of blood flow to the brain and to other major organs was studied during wakefulness and sleep in growing piglets. A young group was studied at 6.8 +/- 1.3 d of age and an older group at 33.5 +/- 5.5 d. Two d before the experiments, we instrumented the animals for measurement of blood flow by the microsphere technique. We determined sleep state using EEG and behavioral criteria. Although we did not find significant differences in blood gas tensions and cardiac output with changes in behavioral states, we did note a number of important changes in brain and muscle blood flow with sleep. 1) Although total brain blood flow changed little between wakefulness and sleep at both ages, regional differences existed. Indeed, at both ages, during rapid eye movement sleep (active sleep), blood flow to the thalamus-hypothalamus and brainstem was significantly higher than during wakefulness (p less than 0.025); in older piglets, blood flow to these two regions was significantly lower in quiet sleep than in wakefulness (p less than 0.05). 2) Blood flow to most skeletal muscle groups, and particularly to the diaphragm, was lower during sleep than during wakefulness. 3) Age did not have a significant effect on the regional distribution of blood flow during sleep. We conclude that behavioral states influence the regional distribution of blood flow in early life, but not in an age-dependent fashion. We speculate that, because no difference was observed in other hemodynamic variables, the regional changes in organ blood flow with sleep most probably reflect the differences in local metabolic needs.     

Phase I and pharmacokinetic study of irinotecan (CPT-11) administered daily for three consecutive days every three weeks in patients with advanced solid tumors

BACKGROUND: We conducted a phase I and pharmacokinetic study to determinethe maximum tolerable dose (MTD), toxicities, pharmacokineticprofile, and antitumor activity of Irinotecan (CPT-11) in patientswith refractory solid malignancies. PATIENTS AND METHODS: Forty-six patients were entered in this phase I study. CPT-11was administered intravenously over 30 minutes for 3 consecutivedays every 3 weeks. Dose levels ranged from 33 mg/m²/day to115 mg/m²/day on days 1 through 3. The pharmacokinetics of totalCPT-11 and its active metabolite SN-38 were assayed by HPLC. RESULTS: The combination of leukopenia and diarrhea was dose-limitingtoxicity at 115 mg/m²/day dose level, since 50% of the patients(5/10) experienced either grade 3–4 leukopenia, or diarrhea,or both. Leukopenia appeared to be a cumulative toxicity, witha global increase in its incidence and severity upon repeatedadministration of CPT-11. Other toxicities included nausea,vomiting, fatigue and alopecia. CPT-11 and active metaboliteSN-38 inetics were determined in 21 patients (29 courses). BothCPT-11 and SN-38 pharmacokinetics presented a high interpatientvariability. CPT-11 mean maximum plasma concentrations reached2034 ng/ml at the MTD (115 mg/m²). The terminal-phase half-lifewas 8.3 h and the mean residence time 10.2 h. The mean volumeof distribution at steady state was 141 l/m²/h. CPT-11 reboundconcentrations were observed in many courses at about 0.5 to1 hour following the end of the i.v. infusion, which is suggestiveof enterohepatic recycling. Total body clearance did not varywith increased dosage (mean=14.3 l/h/m²), indicating linearpharmacokinetics within the dose range administered in thistrial. The total area under the plasma concentration versustime curve (AUC) increased proportionally to the CPT-11 dose.Mean metabolite SN-38 peak levels reached 41 ng/ml at the MTD.A significant correlation was observed between CPT-11 area underthe curve (AUC) and its corresponding metabolite SN-38 AUC (r=0.52,p < 0.05). S-38 rebound concentrations were observed in manycourses at about 0.5 to 1 hour following the end of the i.v.infusion, which is suggestive of enterohepatic recycling. Mean24-h urinary excretion of CPT-11 accounted for 10% of the administereddose by the third day, whereas SN-38 urinary excretion accountedfor 0.18% of the CPT-11 dose. In this phase I trial, the hemato-logicaltoxicity correlated with neither CPT-11 nor SN-38 AUC. Diarrheagrade correlated significantly with CPT-11 AUC. Two partial(breast adenocarcinoma and carcinoma of unknown primary) and2 minor (hepatocarcinoma and pancreatic adenocarcinoma) responseswere observed. CONCLUSION: The MTD for CPT-11 administered in a 3 consecutive-days-every-3weeks schedule in this patient population is 115 mg/m²/day.The recommended dose for phase II studies is 100 mg/m²/day. CPT-11, camptothecin analogue, topoisomerase I inhibitor, phase I, pharmacokinetics     

Contractile leg fatigue after cycle exercise: a factor limiting exercise in patients with chronic obstructive pulmonary disease

We evaluated whether contractile fatigue of the quadriceps occurs after cycling exercise in patients with chronic obstructive pulmonary disease (COPD) and whether it could contribute to exercise limitation. Eighteen COPD patients performed two constant work-rate cycling exercises up to exhaustion. These tests were preceded by nebulization of placebo or 500 microg of ipratropium bromide. Muscle fatigue was defined as a postexercise reduction in quadriceps twitch force of more than 15% of the resting value. There was an increase in endurance time postipratropium compared with placebo nebulization (440 +/- 244 seconds vs. 322 +/- 188 seconds, p = 0.06). Nine patients developed contractile fatigue after placebo exercise. In these patients, ipratropium did not increase the endurance time (394 +/- 220 seconds with placebo vs. 400 +/- 119 seconds with ipratropium) despite an 11% improvement in FEV1. In the nine patients who did not fatigue after placebo exercise, endurance time increased from 249 +/- 124 seconds with placebo to 479 +/- 298 seconds with ipratropium (p < 0.05). There was a significant correlation between the improvement in endurance time with ipratropium and quadriceps twitch force at 10 minutes after placebo exercise (r = 0.59, p = 0.01). The occurrence of contractile fatigue during exercise may explain why bronchodilation fails to improve exercise tolerance in some COPD patients.