Improvement in aged liver regeneration using cell transplantation with chemically induced liver progenitors

BACKGROUND

A decrease in the regenerative capacity of age-damaged liver tissue has been reported. Liver progenitor cells may play an important role in the regeneration of injured livers. In the present study we aimed to investigate improvements in the regenerative capacity of age-damaged livers using chemically induced liver progenitors (CLiPs) derived from mature hepatocytes.

METHODS

Old (>90 weeks) and young (<20 weeks) mice underwent 70% hepatectomy, with or without trans-splenic CLiP administration. The residual liver/bodyweight (LW/BW) ratio was measured on postoperative days 1 and 7, and changes in liver regeneration and histology were evaluated.

RESULTS

At 7 days post-hepatectomy, LW/BW ratios were significantly better in CLiP-treated old mice than in untreated old mice (p = .02). By contrast, no effect of CLiP transplantation was observed in young mice (p = .62). Immunofluorescence staining of liver tissue after CLiP administration showed an increase in Ki67-positive cells (p < .01). Flow cytometry analysis of green fluorescent protein-labeled CLiPs indicated that transplanted CLiPs differentiated into mature hepatocytes and were present in the recipient liver.

CONCLUSIONS

CLiP transplantation appears to ameliorate the age-related decline in liver regeneration in mice.

Chemically Induced Activity Recovery of Isolated Lithium in Anode-free Lithium Metal Batteries

The anode-free lithium metal battery is considered to be an excellent candidate for the new generation energy storage system because of its higher energy density and safety than the traditional lithium metal battery. However, the continuous generation of SEI or isolated Li hinders its practical application. In general, the isolated Li is considered electrochemically inactive because it loses electrical connection with the current collector. Here we show an abnormal phenomenon that the lost capacity appears to be recovered after cycles when the isolated Li reconnects with a deposited Li metal layer. The isolated Li reconnection is ascribed to the chemical induction of the block copolymer coating. The migration of Li⁺ is affected by the electron delocalization and the electron cloud density of the polymer, which determine the conversion direction of Li⁺. Based on the mechanism, we propose a strategy to slow down the capacity decay of the anode-free lithium metal battery.

Influence of various fluoride agents on working properties and surface characteristics of uncoated, rhodium coated and nitrified nickel-titanium orthodontic wires

OBJECTIVE

To analyze the effect of various fluoride formulations in commercially available agents on working properties of various nickel-titanium orthodontic wires.

MATERIALS AND METHODS

Uncoated (NiTi), rhodium coated (RhNiTi) and nitrified (NNiTi) wires were immersed to dH2O, MiPaste, Elmex and Mirafluor for 1 h. Unloading slope characteristics (average force, bending action of the force and average plateau length) and the percentage of useable constant force during unloading were observed. Surface roughness (Ra) was measured. SEM and EDS were used for observation of the surface.

RESULTS

NiTi had decreased loading and unloading elastic modulus (E) and yield strength (YS) after immersion to MIPaste and Mirafluor. The unloading YS decreased in the RhNiTi by the MIPaste. The loading and unloading YS of the NNiTi increased in Elmex and increased average plateau force. RhNiTi showed higher average plateau length and the percentage of useful constant force during unloading in Mirafluor and the average plateau force lowered after immersion to MIPaste. The unloading slope characteristics for NiTi were affected by all three prophylactic agents, mostly by Mirafluor, and produced significantly lower forces during both loading and unloading, similarly to the NNiTi wires. The RhNiTi had the lowest forces during both loading and unloading in MIPaste. All results were at significance; p<0.05. Difference in Ra was observed for RhNiTi after immersion to the MI Paste (p<0.001; η2=0.761).

CONCLUSION

The NiTi and NNiTi wires lose less working force when combined with Elmex. The RhNiTi improve their working properties with Mirafluor and deteriorate when combined with MiPaste.

Evaluation of the association between persistent organic pollutants (POPs) and diabetes in epidemiological studies: a national toxicology program workshop review

BACKGROUND

Diabetes is a major threat to public health in the United States and worldwide. Understanding the role of environmental chemicals in the development or progression of diabetes is an emerging issue in environmental health.

OBJECTIVE

We assessed the epidemiologic literature for evidence of associations between persistent organic pollutants (POPs) and type 2 diabetes.

METHODS

Using a PubMed search and reference lists from relevant studies or review articles, we identified 72 epidemiological studies that investigated associations of persistent organic pollutants (POPs) with diabetes. We evaluated these studies for consistency, strengths and weaknesses of study design (including power and statistical methods), clinical diagnosis, exposure assessment, study population characteristics, and identification of data gaps and areas for future research.

CONCLUSIONS

Heterogeneity of the studies precluded conducting a meta-analysis, but the overall evidence is sufficient for a positive association of some organochlorine POPs with type 2 diabetes. Collectively, these data are not sufficient to establish causality. Initial data mining revealed that the strongest positive correlation of diabetes with POPs occurred with organochlorine compounds, such as trans-nonachlor, dichlorodiphenyldichloroethylene (DDE), polychlorinated biphenyls (PCBs), and dioxins and dioxin-like chemicals. There is less indication of an association between other nonorganochlorine POPs, such as perfluoroalkyl acids and brominated compounds, and type 2 diabetes. Experimental data are needed to confirm the causality of these POPs, which will shed new light on the pathogenesis of diabetes. This new information should be considered by governmental bodies involved in the regulation of environmental contaminants.

5-HT(2B) receptors are required for serotonin-selective antidepressant actions

The therapeutic effects induced by serotonin-selective reuptake inhibitor (SSRI) antidepressants are initially triggered by blocking the serotonin transporter and rely on long-term adaptations of pre- and post-synaptic receptors. We show here that long-term behavioral and neurogenic SSRI effects are abolished after either genetic or pharmacological inactivation of 5-HT(2B) receptors. Conversely, direct agonist stimulation of 5-HT(2B) receptors induces an SSRI-like response in behavioral and neurogenic assays. Moreover, the observation that (i) this receptor is expressed by raphe serotonergic neurons, (ii) the SSRI-induced increase in hippocampal extracellular serotonin concentration is strongly reduced in the absence of functional 5-HT(2B) receptors and (iii) a selective 5-HT(2B) agonist mimics SSRI responses, supports a positive regulation of serotonergic neurons by 5-HT(2B) receptors. The 5-HT(2B) receptor appears, therefore, to positively modulate serotonergic activity and to be required for the therapeutic actions of SSRIs. Consequently, the 5-HT(2B) receptor should be considered as a new tractable target in the combat against depression.

Pulmonary nodules detected by thoracic computed tomography scan after exposure to asbestos: diagnostic significance

OBJECTIVE

To analyse the relationship between pulmonary nodules detected by radiologists using computed tomography and cumulative exposure to asbestos or asbestos-related pleuro-pulmonary diseases in 5662 asbestos-exposed subjects, and the relationship between pulmonary nodules and thoracic cancer, to determine whether a specific surveillance strategy based on cumulative asbestos exposure should be adopted.

DESIGN

Standardised incidence and mortality ratios (SIR) for lung cancer and pleural mesothelioma were calculated in patients with and without mention of pulmonary nodules and compared using comparative morbidity figures.

RESULTS

A significant excess incidence of primary lung cancer and pleural mesothelioma was observed among subjects presenting with pulmonary nodule(s) (SIR respectively 1.95, 95%CI 1.22-2.95, and 11.88, 95%CI 3.20-30.41). However, there was no significant relationship between pulmonary nodules mentioned by radiologists and cumulative asbestos exposure or between pulmonary nodules and the presence of asbestos-related benign diseases.

CONCLUSIONS

This study confirms the expected excess prevalence of lung cancer in subjects presenting with pulmonary nodules according to the radiologist's report, and shows the absence of relationship between the presence of nodules and level of cumulative asbestos exposure. Our study therefore offers no argument in favour of specific surveillance modalities based on estimated cumulative asbestos exposure.

A prospective study of hormone therapy and depression in community-dwelling elderly women: the Three City Study

BACKGROUND

The potential benefits of hormone therapy (HT) in treating depressed postmenopausal women are controversial, and data on depression (re)emergence in the context of HT discontinuation are lacking.

OBJECTIVE

To determine whether HT is associated with a modified risk of new-onset depressive symptoms in elderly women.

METHOD

Current depressive symptomatology was evaluated in 4,069 community-dwelling postmenopausal women aged 65 years and over who were randomly recruited from 3 French cities between 1999 and 2001. Depressive symptomatology was assessed using the Center for Epidemiologic Studies-Depression Scale at baseline and as part of the 2- and 4-year follow-up.

RESULTS

Over the follow-up period, multivariate logistic regression analyses adjusted for sociodemographic variables, measures of physical health, and cognitive impairment failed to find a significant association between HT at baseline and the incidence of depressive symptoms. However further analysis indicated an increased risk of incident depressive symptoms for women using transdermal estradiol treatment combined with synthetic progestin specifically (odds ratio [OR] = 1.59; 95% CI, 1.01-2.50; P = .046). In addition, while women taking HT continuously over the 4-year follow-up did not show an increased risk of depressive symptoms, women who stopped their treatment early after study inclusion, had a significantly higher risk (OR = 2.63; 95% CI, 1.52-4.55; P = .0005).

CONCLUSIONS

Hormone therapy was not associated with a protective effect against the emergence of depressive symptoms in elderly postmenopausal women. However, discontinuing treatment could increase the risk of depressive symptoms. Data on the appropriate management of depression in the context of HT discontinuation among postmenopausal women require further investigation.

Human intestinal microbiota gene risk factors for antibiotic-associated diarrhea: perspectives for prevention. Risk factors for antibiotic-associated diarrhea

Antibiotic-associated diarrhea (AAD) is associated with altered intestinal microflora and other symptoms that may lead to possibly death. In critically ill patients, diarrhea increases rates of morbimortality. Assessing diarrhea risks is thus important for clinicians. For this reason, we conducted a hypothesis-generating study focused on AAD to provide insight into methods of prevention. We evaluated the hypothesis of predisposing factors within the resident intestinal microbiota in a cohort of outpatients receiving antibiotherapy. Among the pool of tested variables, only those related to bacterial 16S rRNA genes were found to be relevant. Complex statistical analyses provided further information: amid the bacteria 16S rRNA genes, eight were determined to be essential for diarrhea predisposition and characterized from the most important to the least. Using these markers, AAD risk could be estimated with an error of 2%. This molecular analysis offers new perspectives for clinical applications at the level of prevention.

Lymphoma in patients treated with anti-TNF: results of the 3-year prospective French RATIO registry

OBJECTIVE

To describe cases of lymphoma associated with anti-TNF therapy, identify risk factors, estimate the incidence and compare the risks for different anti-TNF agents.

METHODS

A national prospective registry was designed (Research Axed on Tolerance of bIOtherapies; RATIO) to collect all cases of lymphoma in French patients receiving anti-TNF therapy from 2004 to 2006, whatever the indication. A case-control analysis was conducted including two controls treated with anti-TNF per case and an incidence study of lymphoma with the French population was used as the reference.

RESULTS

38 cases of lymphoma, 31 non-Hodgkin's lymphoma (NHL) (26 B cell and five T cell), five Hodgkin's lymphoma (HL) and two Hodgkin's-like lymphoma were collected. Epstein-Barr virus was detected in both of two Hodgkin's-like lymphoma, three of five HL and one NHL. Patients receiving adalimumab or infliximab had a higher risk than those treated with etanercept: standardised incidence ratio (SIR) 4.1 (2.3-7.1) and 3.6 (2.3-5.6) versus 0.9 (0.4-1.8). The exposure to adalimumab or infliximab versus etanercept was an independent risk factor for lymphoma in the case-control study: odds ratio 4.7 (1.3-17.7) and 4.1 (1.4-12.5), respectively. The sex and age-adjusted incidence rate of lymphoma was 42.1 per 100 000 patient-years. The SIR was 2.4 (95% CI 1.7 to 3.2).

CONCLUSION

The two to threefold increased risk of lymphoma in patients receiving anti-TNF therapy is similar to that expected for such patients with severe inflammatory diseases. Some lymphomas associated with immunosuppression may occur, and the risk of lymphoma is higher with monoclonal-antibody therapy than with soluble-receptor therapy.

Still no evidence that benzodiazepines cause depression

A large number of drugs have been implicated in causing depression by case reports and case series. For a few specific drugs, the association has subsequently been confirmed by appropriately designed studies. In other instances, a lack of substantiating evidence has lead to a gradual disappearance of concern about a potential association. The benzodiazepines represent a deviation from this pattern: they are widely believed to cause depression, but there is a lack of evidence to substantiate this claim. In DSM-IV, there is a category of mood disorder for drug-induced depression (substance-induced mood disorder), and the text of the manual specifically refers to benzodiazepines as a potential cause. Despite the apparently entrenched nature of this belief, there continues to be a lack of credible evidence that benzodiazepines can cause depression as a side effect.

Polyethylene glycol, unique among laxatives, suppresses aberrant crypt foci, by elimination of cells

OBJECTIVE

Polyethylene glycol (PEG), an osmotic laxative, is a potent inhibitor of colon cancer in rats. In a search for the underling mechanisms, the hypothesis that fecal bulking and moisture decrease colon carcinogenesis was tested. We also investigated the PEG effects on crypt cells in vivo.

MATERIAL AND METHODS

Fischer 344 rats (n=272) were injected with the colon carcinogen, azoxymethane. They were then randomized to a standard AIN76 diet containing one of 19 laxative agents (5% w/w in most cases): PEG 8000 and other PEG-like compounds, carboxymethylcellulose, polyvinylpyrrolidone, sodium polyacrylate, calcium polycarbophil, karaya gum, psyllium, mannitol, sorbitol, lactulose, propylene glycol, magnesium hydroxide, sodium phosphate, bisacodyl, docusate, and paraffin oil. Aberrant crypt foci (ACF) and fecal values were measured blindly after a 30-day treatment regimen. Proliferation, apoptosis, and the removal of cells from crypts were studied in control and PEG-fed rats using various methods, including TUNEL and fluorescein dextran labeling.

RESULTS

PEG 8000 reduced the number of ACF 9-fold in rats (p<0.001). The other PEGs and magnesium hydroxide modestly suppressed ACF, but not the other laxatives. ACF number did not correlate with fecal weight or moisture. PEG doubled the apoptotic bodies per crypt (p<0.05), increased proliferation by 25-50% (p<0.05) and strikingly increased (>40-fold) a fecal marker of epitheliolysis in the gut (p<0.001). PEG normalized the percentage of fluorescein dextran labeled cells on the top of ACF (p<0.001).

CONCLUSIONS

Among laxatives, only PEG afforded potent chemoprevention. PEG protection was not due to increased fecal bulking, but in all likelihood to the elimination of cells from precancerous lesions.

Progestins and progesterone in hormone replacement therapy and the risk of breast cancer

Controlled studies and most observational studies published over the last 5 years suggest that the addition of synthetic progestins to estrogen in hormone replacement therapy (HRT), particularly in continuous-combined regimen, increases the breast cancer (BC) risk compared to estrogen alone. By contrast, a recent study suggests that the addition of natural progesterone in cyclic regimens does not affect BC risk. This finding is consistent with in vivo data suggesting that progesterone does not have a detrimental effect on breast tissue. The increased BC risk found with the addition of synthetic progestins to estrogen could be due to the regimen and/or the kind of progestin used. Continuous-combined regimen inhibits the sloughing of mammary epithelium that occurs after progesterone withdrawal in a cyclic regimen. More importantly, the progestins used (medroxyprogesterone acetate and 19-Nortestosterone-derivatives) are endowed with some non-progesterone-like effects, which can potentiate the proliferative action of estrogens. Particularly relevant seem to be the metabolic and hepatocellular effects (decreased insulin sensitivity, increased levels and activity of insulin-like growth factor-I, and decreased levels of SHBG), which contrast the opposite effects induced by oral estrogen.

Maximum penalized likelihood estimation in a gamma-frailty model

The shared frailty models allow for unobserved heterogeneity or for statistical dependence between observed survival data. The most commonly used estimation procedure in frailty models is the EM algorithm, but this approach yields a discrete estimator of the distribution and consequently does not allow direct estimation of the hazard function. We show how maximum penalized likelihood estimation can be applied to nonparametric estimation of a continuous hazard function in a shared gamma-frailty model withright-censored and left-truncated data. We examine the problem of obtaining variance estimators for regression coefficients, the frailty parameter and baseline hazard functions. Some simulations for the proposed estimation procedure are presented. A prospective cohort (Paquid) with grouped survival data serves to illustrate the method which was used to analyze the relationship between environmental factors and the risk of dementia.

Point: From animal models to prevention of colon cancer. Systematic review of chemoprevention in min mice and choice of the model system

The Apc(Min/+) mouse model and the azoxymethane (AOM) rat model are the main animal models used to study the effect of dietary agents on colorectal cancer. We reviewed recently the potency of chemopreventive agents in the AOM rat model (D. E. Corpet and S. Tache, Nutr. Cancer, 43: 1-21, 2002). Here we add the results of a systematic review of the effect of dietary and chemopreventive agents on the tumor yield in Min mice. The review is based on the results of 179 studies from 71 articles and is displayed also on the internet http://corpet.net/min.(2) We compared the efficacy of agents in the Min mouse model and the AOM rat model, and found that they were correlated (r = 0.66; P < 0.001), although some agents that afford strong protection in the AOM rat and the Min mouse small bowel increase the tumor yield in the large bowel of mutant mice. The agents included piroxicam, sulindac, celecoxib, difluoromethylornithine, and polyethylene glycol. The reason for this discrepancy is not known. We also compare the results of rodent studies with those of clinical intervention studies of polyp recurrence. We found that the effect of most of the agents tested was consistent across the animal and clinical models. Our point is thus: rodent models can provide guidance in the selection of prevention approaches to human colon cancer, in particular they suggest that polyethylene glycol, hesperidin, protease inhibitor, sphingomyelin, physical exercise, epidermal growth factor receptor kinase inhibitor, (+)-catechin, resveratrol, fish oil, curcumin, caffeate, and thiosulfonate are likely important preventive agents.

Most effective colon cancer chemopreventive agents in rats: a systematic review of aberrant crypt foci and tumor data, ranked by potency

Potential chemopreventive agents for colorectal cancer are assessed in rodents. We speculated that the magnitude of the effect is meaningful and ranked all published agents according to their potency. Data were gathered systematically from 137 articles with the aberrant crypt foci (ACF) end point and from 146 articles with the tumor end point. The potency of each agent to reduce the number of ACF is listed in one table and the potency of each agent to reduce the tumor incidence in another table. Both tables are shown in this review and on a website with sorting abilities (http://www.inra.fr/reseau-nacre/sci-memb/corpet/indexan.html). Potency was estimated as the ratio of the value in control rats to the value in treated rats. From each article, only the most potent agent was kept, except in articles reporting the effect of more than seven agents. Among the 186 agents in the ACF table, the median agent reduced the number of ACF by one-half. The most potent agents to reduce azoxymethane-induced ACF were Pluronic, polyethylene glycol, perilla oil with beta-carotene, and sulindac sulfide. Among the 160 agents in the tumor table, the median agent reduced the tumor incidence in rats by one-half. The most potent agents to reduce the incidence of azoxymethane-induced tumors were celecoxib, a protease inhibitor from soy, difluoromethylornithine with piroxicam, polyethylene glycol, and a thiosulfonate. For the 57 agents present in both tables, a significant correlation (r) was found between the potencies against ACF and tumors (r = 0.45, P < 0.001); without celecoxib, a major outlying point in the correlation, r = 0.68 (P < 0.001, n = 56). In conclusion, this review gathers most known chemopreventive agents, ranks the most promising agents against colon carcinogenesis in rats or mice, and further supports the use of ACF as a surrogate end point for tumors in rats.

Neurotensin gene expression and behavioral responses following administration of psychostimulants and antipsychotic drugs in dopamine D(3) receptor deficient mice

Exposure to psychostimulants and antipsychotics increases neurotensin (NT) gene expression in the striatum and nucleus accumbens. To investigate the contribution of D(3) receptors to these effects we used mice with targeted disruption of the D(3) receptor gene. Basal NT mRNA expression was similar in D(3) receptor mutant mice and wild-type animals. Acute administration of haloperidol increased NT gene expression in the striatum in D(3)+/+, D(3)+/- and D(3)-/- mice. Similarly, acute cocaine and amphetamine induced NT mRNA expression in the nucleus accumbens shell and olfactory tubercle to a comparable extent in D(3) mutants and wild-type mice. Daily injection of cocaine for seven days increased NT mRNA in a restricted population of neurons in the dorsomedial caudal striatum of D(3)+/+ mice, but not in D(3)-/- and D(3)+/- animals. No differences were observed between D(3) receptor mutant mice and wild-type littermates in the locomotor activity and stereotyped behaviors induced by repeated cocaine administration. These findings demonstrate that dopamine D(3) receptors are not necessary for the acute NT mRNA response to drugs of abuse and antipsychotics but appear to play a role in the regulation of NT gene induction in striatal neurons after repeated cocaine. In addition, our results indicate that the acute locomotor response to cocaine and development of psychostimulant-induced behavioral sensitization do not require functional D(3) receptors.

Endogenous N-nitroso compounds, and their precursors, present in bacon, do not initiate or promote aberrant crypt foci in the colon of rats

Processed meat intake is associated with increased risk of colorectal cancer. This association may be explained by the endogenous formation of N-nitroso compounds (NOC). The hypothesis that meat intake can increase fecal NOC levels and colon carcinogenesis was tested in 175 Fischer 344 rats. Initiation was assessed by the number of aberrant crypt foci (ACF) in the colon of rats 45 days after the start of a high-fat bacon-based diet. Promotion was assessed by the multiplicity of ACF (crypts per ACF) in rats given experimental diets for 100 days starting 7 days after an azoxymethane injection. Three promotion studies were done, each in 5 groups of 10 rats, whose diets contained 7%, 14%, or 28% fat. Tested meats were bacon, pork, chicken, and beef. Fecal and dietary NOC were assayed by thermal energy analysis. Results show that feces from rats fed bacon-based diets contained 10-20 times more NOC than feces from control rats fed a casein-based diet (all p < 0.0001 in 4 studies). In bacon-fed rats, the amount of NOC input (diet) and output (feces) was similar. Rats fed a diet based on beef, pork, or chicken meat had less fecal NOC than controls (most p < 0.01). No ACF were detected in the colon of bacon-fed uninitiated rats. After azoxymethane injection, unprocessed but cooked meat-based diets did not change the number of ACF or the ACF multiplicity compared with control rats. In contrast, the bacon-based diet consistently reduced the number of large ACF per rat and the ACF multiplicity in the three promotion studies by 12%, 17%, and 20% (all p < 0.01). Results suggest that NOC from dietary bacon would not enhance colon carcinogenesis in rats.

Effect of meat (beef, chicken, and bacon) on rat colon carcinogenesis

High intake of red meat or processed meat is associated with increased risk of colon cancer. In contrast, consumption of white meat (chicken) is not associated with risk and might even reduce the occurrence of colorectal cancer. We speculated that a diet containing beef or bacon would increase and a diet containing chicken would decrease colon carcinogenesis in rats. One hundred female Fischer 344 rats were given a single injection of azoxymethane (20 mg/kg i.p.), then randomized to 10 different AIN-76-based diets. Five diets were adjusted to 14% fat and 23% protein and five other diets to 28% fat and 40% protein. Fat and protein were supplied by 1) lard and casein, 2) olive oil and casein, 3) beef, 4) chicken with skin, and 5) bacon. Meat diets contained 30% or 60% freeze-dried fried meat. The diets were given ad libitum for 100 days, then colon tumor promotion was assessed by the multiplicity of aberrant crypt foci [number of crypts per aberrant crypt focus (ACF)]. The ACF multiplicity was nearly the same in all groups, except bacon-fed rats, with no effect of fat and protein level or source (p = 0.7 between 8 groups by analysis of variance). In contrast, compared with lard- and casein-fed controls, the ACF multiplicity was reduced by 12% in rats fed a diet with 30% bacon and by 20% in rats fed a diet with 60% bacon (p < 0.001). The water intake was higher in bacon-fed rats than in controls (p < 0.0001). The concentrations of iron and bile acids in fecal water and total fatty acids in feces changed with diet, but there was no correlation between these concentrations and the ACF multiplicity. Thus the hypothesis that colonic iron, bile acids, or total fatty acids can promote colon tumors is not supported by this study. The results suggest that, in rats, beef does not promote the growth of ACF and chicken does not protect against colon carcinogenesis. A bacon-based diet appears to protect against carcinogenesis, perhaps because bacon contains 5% NaCl and increased the rats' water intake.

Colonic protein fermentation and promotion of colon carcinogenesis by thermolyzed casein

Thermolyzed casein is known to promote the growth of aberrant crypt foci (ACF) and colon cancer when it is fed to rats that have been initiated with azoxymethane. We speculated that the promotion was a consequence of increased colonic protein fermentation (i.e., that the thermolysis of the casein decreases its digestibility, increases the amount of protein reaching the colon, and increases colonic protein fermentation and that the potentially toxic products of this fermentation promote colon carcinogenesis). We found that the thermolysis of casein reduces its digestibility and increases colonic protein fermentation, as assessed by fecal ammonium and urinary phenol, cresol, and indol-3-ol. Thermolysis of two other proteins, soy and egg white protein, also increases colonic protein fermentation with increased fecal ammonia and urinary phenols, and thermolysis of all three proteins increases the levels of ammonia and butyric, valeric, and i-valeric acids in the cecal contents. We found, however, that the increased protein fermentation observed with thermolysis is not associated with promotion of colon carcinogenesis. With casein, the kinetics of protein fermentation with increasing thermolysis time are clearly different from the kinetics of promotion of ACF growth. The formation of the fermentation products was highest when the protein was thermolyzed for one hour, whereas promotion was highest for protein that had been thermolyzed for two or more hours. With soy and egg white, thermolysis increased colonic protein fermentation but did not promote colon carcinogenesis. Thus, although thermolysis of dietary casein increases colonic protein fermentation, products of this fermentation do not appear to be responsible for the promotion of colon carcinogenesis. Indeed, the results suggest that protein fermentation products do not play an important role in colon cancer promotion.