An in situ FTIR study of the plasma- and thermally-driven reaction of isopropyl alcohol at CeO2: evidence for a loose transition state involving Ce3+?

This paper reports on the thermally-driven and non-thermal plasma-driven reaction of IsoPropyl Alcohol (IPA) on ceria (CeO2) with the aim to investigate the differences between plasma catalytic interactions and the analogous thermal reactions. Both were studied by in situ infrared spectroscopy: using diffuse reflectance for the thermal reaction and reflectance infrared for the plasma. For the thermal reaction, the activity towards the formation of acetone and acetaldehyde and, at higher temperatures, CO2 was dependent upon the coverage of surface carbonates and bicarbonates, suggesting at least some of these species blocked the relevant active sites. However, for the first time, methane and cold CO was observed and this was interpreted in terms of a roaming mechanism taking place at the surface via a loose transition state. By contrast, the plasma-driven process was not inhibited by adsorbed carbonaceous species producing acetone followed by isophorone and a polymethylacetylene-like polymer. Comparisons are made between the equivalent thermal and plasma reactions of isopropyl alcohol on Macor and tin oxide surfaces. On Macor the plasma produced similar products whereas on tin oxide there was no reaction. This suggests that the selection of catalysts for plasma processing cannot necessarily be determined from the equivalent thermal process.

An in situ FTIR spectroscopic and thermogravimetric analysis study of the dehydration and dihydroxylation of SnO2: the contribution of the (100), (110) and (111) facets.

Nanoparticulate SnO2 produced by a hydrothermal method was characterised by BET, XRD, TGA-MS and in situ variable temperature diffuse reflectance infra red spectroscopy (DRIFTS) to determine the surface behaviour of water. For the (100) facets, hydrogen bonding does not occur, and water adsorption is less strong than for the (111) and (110) facets where hydrogen bonding does occur. Reversible uptake of oxygen was observed. These findings have implications for other surface-gas reactions in which Ni and Sb co-doped SnO2 (NATO) anodes are used for ozone generation. BET showed the relatively high surface area and nanometer scale of the SnO2 particles, whilst XRD confirmed the nano dimension of the crystallites and showed only the cassiterite phase. TGA analysis indicated four temperature regions over which mass loss was observed. These and the in situ DRIFTS studies revealed the existence of various forms of water associated with specific crystal facets of the SnO2, as well as the existence of isolated O-H groups and adsorbed oxygen species. Electronic absorptions were also observed and the data rationalised in terms of the existence of both free electron absorptions, and absorptions from oxygen vacancy states. The role of adsorbed molecular oxygen in electrochemical ozone generation at Ni and Sb co-doped SnO2 (NATO) anodes was strongly suggested by this work.

An evaluation of the social and private efficiency of adoption: anaerobic digesters and greenhouse gas mitigation.

Climate science has begun to recognize the important role of non-carbon dioxide greenhouse gas emissions, including methane. Given the important contribution of methane, anaerobic digesters (ADs) on dairy farms in the U.S. present an opportunity to reduce greenhouse gas (GHG) emissions. We quantify the social and private costs and benefits of ADs that have been adopted in California and find that, despite high initial costs, large reductions in GHG emissions bring significant social benefits and represent good social investments given a $36 per-ton social cost of carbon. Subsidies that lower the initial private investment cost can help align socially and privately optimal adoption decisions.

Equipping for risk: Lessons learnt from the UK shale-gas experience on assessing environmental risks for the future geoenergy use of the deep subsurface.

findings are presented from an investigation to improve understanding of the environmental risks associated with developing an unconventional-hydrocarbons industry in the UK. The EQUIPT4RISK project, funded by UK Research Councils, focused on investigations around Preston New Road (PNR), Fylde, Lancashire, and Kirby Misperton Site A (KMA), North Yorkshire, where operator licences to explore for shale gas by hydraulic fracturing (HF) were issued in 2016, although exploration only took place at PNR. EQUIPT4RISK considered atmospheric (greenhouse gases, air quality), water (groundwater quality) and solid-earth (seismicity) compartments to characterise and model local conditions and environmental responses to HF activities. Risk assessment was based on the source-pathway-receptor approach. Baseline monitoring of air around the two sites characterised the variability with meteorological conditions, and isotopic signatures were able to discriminate biogenic methane (cattle) from thermogenic (natural-gas) sources. Monitoring of a post-HF nitrogen-lift (well-cleaning) operation at PNR detected the release of atmospheric emissions of methane (4.2 ± 1.4 t CH4). Groundwater monitoring around KMA identified high baseline methane concentrations and detected ethane and propane at some locations. Dissolved methane was inferred from stable-isotopic evidence as overwhelmingly of biogenic origin. Groundwater-quality monitoring around PNR found no evidence of HF-induced impacts. Two approaches for modelling induced seismicity and associated seismic risk were developed using observations of seismicity and operational parameters from PNR in 2018 and 2019. Novel methodologies developed for monitoring include use of machine learning to identify fugitive atmospheric methane, Bayesian statistics to assess changes to groundwater quality, a seismicity forecasting model seeded by the HF-fluid injection rate and high-resolution monitoring of soil-gas methane. The project developed a risk-assessment framework, aligned with ISO 31000 risk-management principles, to assess the theoretical combined and cumulative environmental risks from operations over time. This demonstrated the spatial and temporal evolution of risk profiles: seismic and atmospheric impacts from the shale-gas operations are modelled to be localised and short-lived, while risk to groundwater quality is longer-term.

Analytical validation of HER2DX genomic test for early-stage HER2-positive breast cancer.

BACKGROUND: HER2DX, a multianalyte genomic test, has been clinically validated to predict breast cancer recurrence risk (relapse risk score), the probability of achieving pathological complete response post-neoadjuvant therapy (pCR likelihood score), and individual ERBB2 messenger RNA (mRNA) expression levels in patients with early-stage human epidermal growth factor receptor 2 (HER2)-positive breast cancer. This study delves into the comprehensive analysis of HER2DX's analytical performance. MATERIALS AND METHODS: Precision and reproducibility of HER2DX risk, pCR, and ERBB2 mRNA scores were assessed within and between laboratories using formalin-fixed paraffin-embedded (FFPE) tumor tissues and purified RNA. Robustness was appraised by analyzing the impact of tumor cell content and protocol variations including different instruments, reagent lots, and different RNA extraction kits. Variability was evaluated across intratumor biopsies and genomic platforms [RNA sequencing (RNAseq) versus nCounter], and according to protocol variations. RESULTS: Precision analysis of 10 FFPE tumor samples yielded a maximal standard error of 0.94 across HER2DX scores (1-99 scale). High reproducibility of HER2DX scores across 29 FFPE tumors and 20 RNAs between laboratories was evident (correlation coefficients >0.98). The probability of identifying score differences >5 units was ≤5.2%. No significant variability emerged based on platform instruments, reagent lots, RNA extraction kits, or TagSet thaw/freeze cycles. Moreover, HER2DX displayed robustness at low tumor cell content (10%). Intratumor variability across 212 biopsies (106 tumors) was <4.0%. Concordance between HER2DX scores from 30 RNAs on RNAseq and nCounter platforms exceeded 90.0% (Cohen's κ coefficients >0.80). CONCLUSIONS: The HER2DX assay is highly reproducible and robust for the quantification of recurrence risk, pCR likelihood, and ERBB2 mRNA expression in early-stage HER2-positive breast cancer.

Profiling undergraduates' generic learning skills on entry to medical school; an international study.

BACKGROUND: Medical education faces challenges posed by widening access to training, a demand for globally competent healthcare workers and progress towards harmonisation of standards. AIM: To explore potential challenges arising from variation in diversity and educational background of medical school entrants. METHOD: This study investigated the reported experience and confidence, in a range of 31 generic skills underpinning learning, of 2606 medical undergraduates entering 14 medical schools in England and South Africa, using a validated questionnaire. RESULTS: Responses suggest that there is considerable similarity in prior educational experience and confidence skills profiles on entry to South African and English medical schools. South African entrants reported significantly more experience in 'Technical skills', 'Managing their own Learning', and 'Presentation', while English students reported increased experience in 'IT' skills. South African undergraduates reported more confidence in 'Information Handling', while English students were more confident in 'IT' skills. The most noticeable difference, in 'IT' skills, is probably due to documented differences in access to computer facilities at high school level. Differences between individual schools within each country are noticeable. CONCLUSIONS: Educators need to acquire a good understanding of their incoming cohorts, and ensure necessary tailored support for skills development.

The optimal cut-off for predicting large oesophageal varices using transient elastography is disease specific.

The diagnosis of cirrhosis requires screening for oesophageal varices by upper gastrointestinal endoscopy. In many countries, serological tests and elastography are replacing liver biopsy for diagnosing cirrhosis. The aims of this study were to see whether there was an optimal cut-off of liver stiffness that could predict the presence of large (>F2) oesophageal varices and whether this was disease specific. A total of two hundred and twenty-two patients with all cause cirrhosis (Child class A) were screened, and 211 had successful elastography and are included in the analysis. Of the patients studied, one hundred and thirty-two patients had no or small F1 varices and 79 had large varices. Liver stiffness of 19.8 kPa had a negative predictive value of 91% and a positive predictive value of 55% with an area under the curve (AUC) on receiver operating characteristics (ROC) of 0.73 in differentiating between small and large varices. Seven patients with large varices would have been incorrectly classified. In the 157 patients with hepatitis C as the aetiology of cirrhosis, the negative predictive value was 98% and only one patient was misclassified. Liver stiffness was superior in diagnostic accuracy to platelet count in all patients. A liver stiffness of >19.8 kPa could be utilized as a cut-off for endoscopy and beta blocker utilization, particularly in patients with hepatitis C.

Silicate production and availability for mineral carbonation.

Atmospheric carbon dioxide sequestered as carbonates through the accelerated weathering of silicate minerals is proposed as a climate change mitigation technology with the potential to capture billions of tonnes of carbon per year. Although these materials can be mined expressly for carbonation, they are also produced by human activities (cement, iron and steel making, coal combustion, etc.). Despite their potential, there is poor global accounting of silicates produced in this way. This paper presents production estimates (by proxy) of various silicate materials including aggregate and mine waste, cement kiln dust, construction and demolition waste, iron and steel slag, and fuel ash. Approximately 7-17 billion tonnes are produced globally each year with an approximate annual sequestration potential of 190-332 million tonnes C. These estimates provide justification for additional research to accurately quantify the contemporary production of silicate minerals and to determine the location and carbon capture potential of historic material accumulations.

Immunosuppression of mice injected with heterologous anti-immunoglobulin heavy chain antisera.

Neonatal injection of mice with rabbit anti-micro antiserum has been shown to produce complete loss of direct and indirect plaque-forming responses to sheep erythrocytes as well as loss of serum IgM and severe depressions of all other serum immunoglobulins. Similar injection of anti-gamma1gamma2 or anti-gamma1 antibodies effects a loss of the indirect response but induces relatively minor alterations in serum Ig levels. Delaying initiation of anti-micro treatment until young adulthood results in a somewhat diminished effect on plaque-forming responses and serum Ig levels but triggers the release of high serum levels of an aberrant micro-bearing protein. Anti-micro suppression of genetically thymusless mice indicates that at least part of the target cells for suppression are bone marrow derived. A working hypothesis for the maturation of humoral antibody-producing cell lines as it relates to these data is discussed.

Maintenance of skin xenografts of widely divergent phylogenetic origin of congenitally athymic (nude) mice.

Congenitally athymic (nude) mice accepted for their lifetime intact skin grafts from distantly related mammals (cat, human) and birds (chicken). They also failed to immunologically reject skin grafts from reptiles (lizards) and amphibians (tree frog), although the skin in these grafts underwent varying degrees of disorganization. A definitive role for the thymic defect in this failure to reject xenografts was established by showing that thymus implantation into nude mice enabled them to reject such foreign skin.

Suppression of reaginic antibody (IgE) formation in mice by treatment with anti-mu antiserum.

Neonatally initiated injection of anti-mu antiserum in mice has been shown to suppress the formation of reaginic antibodies in response to infection with the intestinal nematode, Nippostrongylus brasiliensis. This observation supports the hypothesis that IgE-producing cells arise from IgM-bearing precursors.

Transplantation of cultured thymic fragments. II. Results in nude mice.

Nine nude mice were transplanted with cultured thymic fragments derived from syngeneic (three recipients) or allogeneic (six recipients) sources. All transplanted mice survived for periods of up to 8-10 mo thereafter, at which time they were sacrificed. Weight gain had been progressive and the animals were in excellent health. Four nontransplanted littermates housed in the same cages died at the age of 4 mo. In the nontransplanted mice, the usual deficits of T and B cells were observed. In transplanted mice, normalization of IgG1 and IgA levels as well as IgG antibodies to sheep erythrocytes and precipitating antibodies to rabbit serum occurred. Lymphocyte counts and Thy-1 bearing cells increased to approximately 50% of normal values. Proliferative responses to phytohemagglutinin and concanavalin A, mixed leukocyte reactivity, and cell-mediated lympholysis were variably restored from approximately 10-100% of normal. Attained responses were the same in recipients of syngeneic or allogeneic tissues and these, in turn, were equal or superior to responses measured in animals transplanted with whole noncultured thymuses. Skin grafts from third party donors were vigorously rejected, whereas those derived from second party (allogeneic thymus donor strain) may have been accepted or slowly rejected. Cultured thymic fragments, consisting primarily of epithelial elements, can effectively repair the thymic deficiency of nude mice. Experiments to date do not indicate that syngeneic tissues enjoy an advantage over allogeneic grafts in this restoration procedure.

Transfusion support for a patient with McLeod phenotype without chronic granulomatous disease and with antibodies to Kx and Km.

BACKGROUND AND OBJECTIVES: Kell antigens are encoded by the KEL gene on the long arm of chromosome 7. Kx antigen is encoded by the XK gene on the short arm of the X chromosome. Kell and Kx proteins in the red cell membrane are covalently linked by a disulphide bond. The McLeod phenotype is characterized by weakened expression of antigens in the Kell blood group system, absence of Km and Kx antigens, and acanthocytosis. It has an X-linked mode of inheritance with transmission through carrier females. Some males with the McLeod syndrome also have chronic granulomatous disease (CGD). It is generally believed that patients with non-CGD McLeod may develop anti-Km but not anti-Kx, but that those with CGD McLeod can develop both anti-Km and anti-Kx. MATERIALS AND METHODS: We present serological data, DNA genotyping and gene sequencing, monocyte monolayer assay and neutrophil oxidative burst test from a patient with the McLeod phenotype without clinical evidence of CGD. RESULTS: We report here the second example of a patient with non-CGD McLeod who developed anti-Kx in addition to anti-Km. Sequencing of our patient's XK gene confirmed the presence of a mutation resulting in a premature stop codon and lack of Kx protein in the red cell membrane, which is consistent with the diagnosis of McLeod syndrome. Neutrophil oxidative burst test was normal, indicating that our patient did not have CGD. The challenge of providing 10 compatible blood units for multiple surgeries was met. CONCLUSION: The second case of a rare entity, a patient with non-CGD McLeod who developed anti-Kx and anti-Km, was managed successfully with a combination of autologous donations and procurement of compatible units from national and international sources.

Evaluation of adherence to highly active antiretroviral therapy in adults in Jamaica.

BACKGROUND AND PURPOSE: Highly active antiretroviral therapy (HAART) has improved morbidity and mortality and quality of life, revitalized communities and transformed the perception of HIV/AIDS from being a "death sentence" to a chronic illness. Strict and sustained adherence to medication is essential long-term viral suppression. In April 2005, an Adherence Support Programme was introduced to Jamaica's HIV Programme, whereby Persons Living with HIV/AIDS (PLWHA) who had achieved high levels of adherence were trained to provide support to other PLWHA in order to increase their adherence to HAART regimens. METHODS: A cross-sectional survey of 116 individuals with advanced HIV and on HAART was performed in June and July 2006. RESULTS: Many participants were unemployed, poor persons with limited education. Based on self-report of seven-day adherence, 54.8% of persons were 95-100% adherent, 37.5% were 80-94% adherent and 7.7% were < 80% adherent. Having interacted with an adherence counsellor was not associated with adherence levels. Factors associated with nonadherence were: being away from home (38%), sleeping through dose-time (37%), forgetfulness (37%) and running out of pills (31%). Having no food (26.9%), not wanting to be seen taking medication (200%) and intolerable side effects (18.8%) were also reasons given. Only 44% of persons used aids to remind them of dose times. CONCLUSION: Adherence in this study group is low and may have worsened since 2005. More emphasis must be placed on preparing adults to start HAART The use of pillboxes and other reminders such as alarm clocks and cell phones must be reinforced.

A randomized, double-blind, placebo-controlled trial of lenalidomide in the treatment of moderately severe active Crohn's disease.

BACKGROUND: Therapy targeted at tumour necrosis factor-alpha has an established role in Crohn's disease. Lenalidomide, an analogue of thalidomide, is an oral immunomodulatory agent with powerful antitumour necrosis factor-alpha properties. It is licensed for myeloma and myelodysplastic syndrome. Based upon reports of thalidomide efficacy, lenalidomide was evaluated in Crohn's disease. AIM: To evaluate the efficacy and safety of lenalidomide in subjects with moderately severe active Crohn's disease. METHODS: In a multicentre, double-blind, placebo-controlled parallel group study 89 subjects were randomized to lenalidomide 25 mg daily, 5 mg daily or placebo. Subjects were treated for 12 weeks. The primary end point was a 70-point reduction in Crohn's Disease Activity Index. RESULTS: The overall clinical response rate was not significantly different between the three groups: lenalidomide 25 mg 26%, lenalidomide 5 mg 48% and placebo 39%. Lenalidomide was generally well tolerated with only one serious adverse event, a deep vein thrombosis, being attributed to treatment. CONCLUSION: Lenalidomide, an oral agent with antitumour necrosis factor-alpha properties, was not effective in active Crohn's disease in contrast to reports of benefit from thalidomide. The reasons for this lack of efficacy are speculative, other physiological activities may offset its action on inflammatory cytokines, or its antitumour necrosis factor-alpha action without apoptosis may be insufficient for activity in Crohn's disease.

Evaluating an anaerobic digestion (AD) feedstock derived from a novel non-source segregated municipal solid waste (MSW) product.

In many nations industrial scale AD of non-agricultural waste materials (such as MSW) has not yet reached its full potential, often constrained by the lack of secure, inexpensive, high quality AD feedstocks, and markets for the resulting digestate material. We tested the output material of a high throughput novel industrial process to define its potential as an AD feedstock (based on quality and consistency). This process, designed to circumvent the constraints of source segregation while still generating segregated waste streams, resulted in the production of a temporally homogenous fibrous material with: an average moisture content of 44.2 (±2.33)%; C:N ratio of ∼32.9:1 (±3.46:1), C:P ratio of ∼228:1 and gross calorific value of 17.4 (±0.29)MJ/kg(DM). This material provided a CH4 yield of between 201 and 297m3 CH4/tonne(DM) (271-401m3CH4/tonne(vs)) comparable to commonly used AD feedstocks. Material contaminant levels were temporally consistent (P>0.05), (average values being Cd 0.63 (±0.19), Cu 56.3 (±7.45), Crtot 51.4 (±4.41), Hg<0.3, Ni 28.9 (±5.17), Pb 79.2 (±23.71), Zn 202 (±44.5), total polyaromatic hydrocarbons (PAH) 2.2 (±0.3), and total polychlorinated biphenyls (PCB) (<0.2)mg/kg(DM)). Calculated digestate contaminant levels were below the median contaminant threshold limits for anaerobic digestates of all countries within the European Union i.e. of Cd 3.35, Cu 535, Crtot 535, Hg 8.15, Ni 185, Pb 397.5, Zn 2100mg/kg(DM). We suggest that novel high throughput processes that produce high quality AD feedstocks, may have a place in further diversion of waste from landfill.

Time-dependent observer errors in pulmonary nodule detection.

The work was carried out to investigate differences in visual search characteristics between groups of observers with different levels of experience in the task of pulmonary nodule detection in chest radiology and we report here on these differences in respect of time related decisions. Volunteer observers were divided into three groups depending on their level of expertise. There were eight radiologists, eight radiographers and eight novices. Their task was to detect pulmonary nodules in a test bank of 120 digitized posteroanterior (PA) chest radiographs. Five of the eight radiographers were tested twice: once before and once after a 6-month training programme in interpretation of the adult chest radiograph. During each test session the observers' eye movements were tracked. Data on the observers' decisions through Alternate Free Response Operating Characteristic (AFROC) methodology were correlated to their eye-movement and fixation patterns. True negative decisions from all observers were associated with shorter fixation times than false negative decisions. No correct negative decisions were made after fixations exceeding 3 s.

Comparison of the effects of a pure steroidal antiestrogen with those of tamoxifen in a model of human breast cancer.

BACKGROUND: Tamoxifen, a nonsteroidal estrogen antagonist, is the most prescribed drug for the treatment of breast cancer. The use of tamoxifen is limited, however, by the development of resistance to this compound in most patients. Although tamoxifen behaves primarily as an estrogen antagonist, it has agonist (or growth-stimulatory) activity as well. ICI 182,780 is a 7 alpha-alkylsulfinyl analogue of estradiol lacking agonist activity. The absence of agonist activity may make this steroidal antiestrogen superior to tamoxifen in suppressing tumor cell growth. PURPOSE: We compared the inhibitory effects of ICI 182,780, tamoxifen, and estrogen withdrawal on the growth of established tumors and on tumorigenesis in a model system that uses estrogen-dependent, human MCF-7 breast tumor cells growing in athymic nude mice. We also studied the hormonal responsiveness of tumors that became resistant to the two estrogen antagonists and the effects of these drugs on estrogen-regulated gene expression. METHODS: MCF-7 cells were injected subcutaneously into the flanks of castrated, female nude mice. The effects of repeated doses of tamoxifen and ICI 182,780 (500 micrograms and 5 mg, respectively) on the growth of established tumors (8-10 mm in size) were determined after supplemental estrogen was removed. The effects of antiestrogen treatments on the process of tumorigenesis, in the absence of estrogen supplementation, were determined by initiating drug administration on the same day as tumor cell inoculation. To evaluate the hormonal responsiveness of tumors resistant to tamoxifen and ICI 182,780, 1-mm3 segments of the tumors were transplanted onto the flanks of new recipient mice, which were then treated with estrogen or the antiestrogens--alone or in combination. Tumor growth was monitored by measuring tumor volumes twice a week. Expression of the estrogen-responsive genes, pLIV1 and pS2, in the tumors of treated animals was analyzed using blots of total cellular RNA and complementary DNA probes. RESULTS: Treatment with ICI 182,780 suppressed the growth of established tumors twice as long as treatment with tamoxifen or estrogen withdrawal. Tumorigenesis, in the absence of supplemental estrogen, was delayed to a greater extent in ICI 182,780-treated mice than in tamoxifen-treated mice. ICI 182,780 was found to be more effective than tamoxifen in reducing the expression of estrogen-regulated genes. Most tumors eventually became resistant to ICI 182,780 and grew independently of estrogen. CONCLUSIONS: ICI 182,780 is a more effective estrogen antagonist than tamoxifen in the MCF-7 tumor cell/nude mouse model system.

Cloning of estrogen-responsive messenger RNAs in the T-47D human breast cancer cell line.

A complementary DNA library has been constructed from the polyadenylated mRNA of steroid-deprived T-47D cells which had been restimulated with estrogen for 24 h. Screening of 15,000 recombinants by sequential rounds of colony, Southern and Northern blot differential hybridization has identified eight different clones which vary in abundance and are stimulated between 2.5- and 8-fold by estrogen. Whereas five recombinants hybridize to single mRNA sequences, two clones, pSyd 2 and pSyd 8, appear to hybridize weakly to an addition mRNA sequence and one clone, pSyd 3, hybridizes to a multiple mRNA species (1.9, 1.7, 0.9, and 0.5 kilobases). Furthermore, at least one clone, pSyd 2, appears to be expressed only in ER-positive cells. While its level of expression is stimulated by estrogen approximately 4-fold in all the estrogen and progesterone receptor-positive cell lines tested (T-47D, ZR-75-1, and MCF-7), pSyd 2 levels in the estrogen and progesterone receptor-negative HBL-100 cell line were lower than the corresponding levels in estrogen-stimulated T-47D cells and were unresponsive to estradiol. These results show that we have isolated several estrogen-responsive sequences which will be useful in studying hormone regulation of gene expression and may provide additional markers of hormone responsiveness in breast cancer.

Heterotopic urinary bladder with a communicating reservoir.

A heterotopic bladder attached to an Ommaya reservoir was transplanted to the back of a syngeneic rat. Following transplantation, the mucosa underwent ischemic necrosis. However, it was rapidly reepithelialized in 2 weeks as a result of spreading of the epithelium originating from the ureterotrigonal region. By light microscopy the regenerated epithelium was indistinguishable from the normal transitional epithelium, and the cannula connecting the reservoir to the bladder remained patent throughout the observation period of 22 weeks. One bladder, when examined at 22 weeks, contained a transitional cell papilloma with squamous metaplasia. Although further study is needed, this model is potentially useful in studies related to bladder carcinogenesis.