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The present study was designed to determine whether there are any age-related changes in the repair of acute gastric mucosal injury induced by aspirin in Fischer 344 rats. We have also examined the influence of aging on gastric mucosal proliferative activities, a major component of gastric mucosal defense and repair mechanisms. Our data demonstrated that aging was associated with significant delays in both resolution of gross mucosal injury and regeneration of the injured gastric mucosa. However, there were no correlations between the regeneration of the injured gastric mucosa and gastric mucosal expression of proliferating cell nuclear antigen and transforming growth factor-alpha immunoreactivities. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine if selective inhibition of cyclooxygenase isozymes affects the initiation of carcinogen-induced colon cancer using aberrant crypt foci (ACF) as a surrogate biomarker. Male Sprague-Dawley rats (18 per group) were given single subcutaneous injections of saline (4 ml/kg), aspirin (50 mg/kg body wt) sodium salicylate (50 mg/kg), indomethacin (4 mg/kg), nabumetone (100 mg/kg), or 16,16-dimethyl-prostaglandin E2 (50 mg/kg) for three days. On day 4, 12 rats per group were given a subcutaneous injection of 1,2-dimethylhydrazine (12 mg base/kg body wt) and six rats per group received vehicle alone (4 ml/kg) every week for eight weeks, after which drug treatment ceased. Control and six carcinogen-treated rats per group were killed at this time and the remaining six rats per group killed 22 weeks later. Colons were scored for ACF number and size. Only aspirin caused a significant reduction in total ACF and ACF formation at the early time point, but at the later time, there were no significant differences between groups. ACF from all treatment groups increased in size at similar rates at both time points. Thus, only aspirin demonstrated a significant, although reversible, suppression of carcinogen-induced ACF. Possible mechanisms of action and the clinical implications of aspirin chemoprevention are discussed. [ABSTRACT FROM AUTHOR]

Background: A new approach to cancer therapy based on the application of therapeutic electromagnetic fields (TEMF) has been developed by EMF Therapeutics, Inc., Chattanooga, TN, USA. This study was designed to assess the effect of TEMF on tumor vascularization and growth of murine 16/C mammary adenocarcinoma cells in C3H/HeJ mice., Materials and Methods: Implanted tumors were allowed to grow for seven days until the tumor volume reached 100 mm3 before treatment was started. Mice (20 per control, 10 per EMF exposed group) received treatment (10 minutes per day with 0, 10 mT, 15 mT or 20 mT) with a 120 pulses per second pulsating magnetic field. Tumor growth was assessed throughout the treatment period. The extent of tumor vascularization was evaluated by immunohistochemical staining for CD31., Results: Exposure to TEMF significantly reduced tumor growth, significantly reduced the percentage of area stained for CD31 indicating a reduction in the extent of vascularization and there was a concomitant increase in the extent of tumor necrosis., Conclusion: A novel TEMF treatment safely reduced growth and vascularization of implanted breast cancers in mice., Implication: TEMF may prove a useful adjuvant to increase the therapeutic index of conventional cancer therapy.

Omega 3 polyunsaturated fatty acids (the type of fat found in fish oil) have been used to kill or slow the growth of cancer cells in culture and in animal models and to increase the effectiveness of cancer chemotherapeutic drugs. An AIN-76 diet containing 5% corn oil (CO) was modified to contain 3% w/w fish oil concentrate (FOC) and 2% CO to test whether a clinically applicable amount of FOC is beneficial during doxorubicin (DOX) treatment of cancer xenografts in mice. Compared with the diet containing 5% CO, consumption of FOC increased omega 3 polyunsaturated fatty acids and lipid peroxidation in tumor and liver, significantly decreased the ratio of glutathione peroxidase activity to superoxide dismutase activity (a putative indicator of increased oxidative stress) in tumor but not in the liver, and significantly decreased the tumor-growth rate. The decreased glutathione peroxidase:superoxide dismutase ratio, indicating an altered redox state, in the tumor of FOC-fed mice was significantly correlated with decreased tumor-growth rate. Assay of the body weight change, blood cell counts, and number of micronuclei in peripheral erythrocytes indicated that the toxicity of DOX to the host mouse was not increased in mice fed FOC. Thus, a small amount of FOC increased the effectiveness of DOX but did not increase the toxicity of DOX to the host mouse. These positive results justify clinical testing of FOC in conjunction with cancer chemotherapy.

Given that human cancer xenografts tend to retain chemosensitivities similar to the cancerous tissue of origin, human carcinoma xenografts grown in nude mice were tested for sensitivity to four drug protocols: doxorubicin at 5 mg/kg, i.v., q5d; irinotecan at 60 mg/kg, i.v., q4d; cisplatin 5 mg/kg, i.p., q7d; and topotecan 1.5 mg/kg, p.o., qd (5 of 7 days). Irinotecan and doxorubicin protocols either halted or caused significant regression of the breast cancer cell lines (MCF7, MDA-MB 231 and T47D). None of the protocols tested resulted in significant regression in the lung cancer xenografts (H460, A549 and H226) although both irinotecan and doxorubicin did halt growth of the H226 xenograft. The ability of the irinotecan treatment to cause regression of xenograft size in all three colon cancer cell lines (SW620, COLO205 and HT29) justifies further clinical trials of irinotecan as an especially promising drug for the treatment of colon cancer.

Colorectal cancer is the second-most frequent cause of cancer mortality in the United States. Human epidemiology and laboratory studies indicate that aspirin may be an effective colorectal cancer chemopreventive agent. This study was designed to determine whether treatment with 81 mg of aspirin per day for 3 months would alter two putative surrogate end point biomarkers of chemoprevention of colorectal cancer [i.e., mucosal prostaglandin E2 (PGE2) formation and transforming growth factor alpha (TGF-alpha) expression] in normal-appearing rectal mucosa from individuals with a history of adenomatous polyps. Rectal biopsies were obtained by flexible sigmoidoscopy at three sequential time points: (a) after a 1-month placebo run-in period (baseline), (b) after 3 months of ingesting 81 mg of aspirin (as a single tablet) once per day, and (c) after 3 months of ingesting a placebo tablet once per day (washout period). Daily aspirin significantly suppressed PGE2 formation, but this significant suppression was completely reversed when aspirin was withdrawn. The extent of TGF-alpha staining in rectal crypts was also reduced significantly (P = 0.039) by daily aspirin. After a 3-month placebo-washout period, however, the mean extent of TGF-alpha staining was not significantly different from either baseline or the aspirin time point. Thus, 81 mg of aspirin daily significantly reduced rectal mucosal PGE2 formation and TGF-alpha expression in patients with a history of adenomatous polyps. These putative surrogate end point biomarkers may be useful intermediate end points in future colorectal cancer chemoprevention trials.

To determine whether colon crypt proliferative parameters were significantly altered by the stage of colon carcinogenesis or the type or location of colon tumors in rats, male Sprague-Dawley rats received an injection of the carcinogen 1,2-dimethylhydrazine (12 mg DMH base/kg body weight) or DMH vehicle once a week for 8 weeks, then were killed 24 weeks later. Three hours before sacrifice, rats were injected with 1 mg/kg body weight colchicine to arrest mitotic cells at metaphase. Transverse sections of the colon mucosa were taken 6 cm from the anus and at least 3 cm from any tumor, fixed in formalin, then stained with hematoxylin & eosin (H&E) for analyses of proliferative parameters. Only complete, mid-axial crypts were scored for mitotic count (MC), crypt proliferative zone (PZ) height and crypt height (CH). Serial tumor sections were stained with H&E for histological evaluation or used in immunohistochemical detection of transforming growth factor alpha (TGF alpha). DMH treatment significantly increased MC, PZ and CH regardless of tumor status. The PZ and CH of rats with a carcinoma located in the distal colon were significantly increased compared with DMH-treated rats without an adenocarcinoma (AC) or with rats which had a tumor located in the proximal colon. Distal colon ACs were found to be well differentiated and to have greater TGF alpha immunoreactivity than the generally less differentiated proximal colon carcinomas. Distal colon AC production and systemic circulation of a soluble colon crypt stimulating factor such as TGF alpha may explain the significant increase in PZ and CH in histologically normal colonic mucosa located away from the tumor.

Data from rat experimental carcinogenesis studies indicate that supplemental dietary cellulose reduces the incidence of colon cancer. Epidemiology studies also indicate that high dietary fiber reduces the risk of colorectal cancer in humans. Patients diagnosed with sporadic adenomas were entered into a randomized clinical trial to determine if supplemental dietary cellulose would reduce the patients' risk for colon cancer. Immunohistochemical staining for transforming growth factor alpha (TGF-alpha) was done on biopsies of rectal mucosa taken from patients at the time of initial polypectomy and 1 year later. Results were evaluated for utility as a surrogate end point biomarker for reduction in colon cancer risk. There was a significant decrease in the fraction of the rectal crypt cells that stained for TGF-alpha in six of seven of the patients given the cellulose supplements but in only one of six of the patients not given cellulose. Thus, whether evaluated as a group or in individual patients, there was a significant decrease in TGF-alpha in rectal crypts due to cellulose intervention, which correlated with the expected ability of supplemental dietary cellulose to decrease the risk for colon cancer. Long-term testing of the ability of dietary cellulose to reduce adenoma recurrence is under way to validate the use of TGF-alpha as a surrogate end point biomarker.

The aim of this study was to characterize colon tumor development and invasiveness associated with dietary zinc deprivation. Colon carcinogenesis was initiated by eight weekly subcutaneous injections of 1,2-dimethylhydrazine (DMH) at 12 mg DMH base/kg body wt in groups of mice maintained on diets containing 30 micrograms/kg dietary zinc (zinc adequate, ZA) or 3 micrograms/kg dietary zinc (zinc deprived, ZD). All mice were killed 24 weeks after the last injection of DMH. Mean zinc concentration in the liver was significantly lower in the ZD group than in the ZA group. The total number of grossly detectable colon tumors was the same in both dietary groups. However, histopathological study of each tumor revealed significantly more adenomatous polyps (AP) and invasive adenocarcinomas (CA) in the ZA group, whereas the ZD group had significantly more noninvasive carcinomas in situ (CIS). It appears that zinc deprivation stimulated progression of AP to noninvasive CIS but retarded the progression of noninvasive CIS to invasive CA. Immunohistochemistry of tumors from ZA and ZD mice indicated increased amounts of type IV collagenase in epithelial tumor cells and in stromal cells adjacent to tumor tissue regardless of the amount of dietary zinc consumed. It is suggested that zinc deprivation may limit function of zinc-requiring enzymes such as superoxide dismutase and type IV collagenase, resulting in enhanced progression of AP to noninvasive CIS and retardation of invasion of CIS to become CA, respectively.

The effect of supplementation of the diet with autohydrolyzed lignin on 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis was studied using 112 male Sprague-Dawley rats. Rats received eight weekly injections of DMH (9.5 mg/kg s.c.) or the saline vehicle solution and then were maintained on a basal AIN-76 fiber-free diet or the basal fiber-free diet plus 5% or 10% (wt/wt) lignin for 24 weeks. Rats were killed 32 weeks after the start of the experiment. Colon tumor incidence, location, and multiplicity were determined. Body weight, caloric intake, fecal dry weight, gut transit time, pH of cecal contents, and total fecal bile acid excretion were measured. Supplementation of the diet with 5% or 10% lignin resulted in increased fecal dry weight and total fecal bile acid excretion and in decreased gut transit time, colon pH, and fecal bile acid concentration. Dietary lignin did not significantly affect colon tumor incidence or multiplicity compared with the fiber-free diet. Thus dietary supplementation with autohydrolyzed lignin, a food fiber with good bulking characteristics, had a significant effect on several factors that have previously been linked to reduction of colon cancer risk, but the consumption of high levels of lignin did not decrease the risk for colon cancer.

If the plasma membrane and its associated transport proteins are solely responsible for maintenance of the asymmetric solute distribution then disruption of the plasma membrane would quickly lead to the symmetric distribution of all unattached inorganic ions between the cell and the extracellular environment. To test this hypothesis fresh pig lenses were incubated in Hanks' balanced salt solution in either absence or presence of non-ionic detergents (0.2% Triton X-100 or 0.2% Brij 58). Both detergents caused permeabilization of every lens fiber cell as shown by electron microscopy. The flux kinetics of K+, Mg2+, Na+, Ca2+, water and protein out of and into the permeabilized lens fiber cells was measured. Triton X-100 caused a faster flux rate of all solutes than did Brij 58. The Triton X-100 induced flux of solutes and water was associated with a decrease in lens ATP. Incubation of untreated lenses in solutions of different osmotic pressures at 0 degree C demonstrated that the major fraction of lens water was osmotically unresponsive. Thus the asymmetric distribution of solutes in lens fiber cells is dependent on an intact plasma membrane and on a co-operative ATP-dependent association between K+, Mg2+, water and cytomatrix proteins.

The effects of specific dietary interventions on incidence of carcinogen-induced cancer and on cryptal cell proliferation in areas of the colon located either over aggregates of lymphoid nodules (ALN) or away from ALN was investigated. Groups of dimethylhydrazine (DMH) treated rats or non-DMH-treated rats were fed a basal AIN-76 diet less fiber of any type, or the basal fiber free diet supplemented with 10% pectin and with 5%, 10%, or 20% corn oil. The adenocarcinoma (AC) incidence was determined in regions of the colon, i.e. ascending, descending, descending over the ALN and descending away from the ALN. The results indicate that: (i) factors associated with ALN promote AC formation, (ii) dietary modifications (addition of pectin and of 20% corn oil to the diet) each cause significant site specific suppression of AC incidence, (iii) DMH-treatment rendered crypts non-responsive to the suppression of cryptal cell proliferation which occurred in the rats not treated with DMH (suggestive of a DMH-induced loss in the regulation of cell proliferation) and (iv) reduction of AC incidence was not always accompanied by reduction in crypt cell proliferation. Studies of intervention procedures designed to prevent colon cancer should take into account the colon site specific tumorigenic response to the preventive agent and should not rely on a single biomarker to predict the efficacy of the intervention.

Male, Sprague-Dawley rats were injected subcutaneously with the colon carcinogen 1,2-dimethylhydrazine (DMH) at a dosage of 9.5 mg DMH base/per kg rat body weight once weekly for 8 weeks; control rats received an equivalent volume of the vehicle. Analyses of variance showed that in carcinogen-treated as well as in non-carcinogen-treated rats, the proliferative zone height and the crypt height in colonic crypts located over the aggregates of lymphoid nodules (ALN) were significantly higher than in colonic crypts located away from the ALN. Immunohistochemical localization of transforming growth factor alpha (TGF alpha) showed that this mitogenic factor was found in cells in the proliferative zone of colonic crypts located over the ALN, but TGF alpha was not detectable in cells in the proliferative zone of colonic crypts located away from the ALN. Examination of histological sections of the colon taken through the ALN of DMH-treated rats revealed that eight out of 25 DMH-treated rats had microscopic adenocarcinomas (AC) within the ALN, but in the same rats no microscopic AC were seen in histological sections taken away from the ALN. Furthermore, there was no evidence of an adenomatous precursor to these microscopic, endophytic AC, suggesting that the endophytic AC arose de novo. Therefore, because of (i) the significantly higher proliferative activity in colonic crypts located over the ALN, (ii) the localization of TGF alpha in the proliferative zone of the colonic crypts associated with ALN and (iii) the high incidence of endophytic AC associated with ALN, it seems likely that factors emanating from the ALN are promotional to carcinogenesis in the colonic epithelium that is located in close proximity to the ALN.

Six-week-old male CF-1 mice were fed the AIN-76 diet, given eight weekly s.c. injections of either the colon carcinogen 1,2-dimethylhydrazine or saline, and killed 24 weeks after the last injection. Parameters measured in the large bowel included the incidence and locations of all intestine (gut)-associated lymphoid tissue (GALT) sites; the locations, incidence, and sizes of all aberrant crypt foci (ACF); and the incidence, locations, and types of all overt tumors. In saline-treated mice the distribution of GALT along the length of the large bowel was bimodal, with a majority peak of lymphoid nodules occurring in the distal large bowel and a minority peak occurring in the proximal large bowel. No ACF or tumors were present in the large bowel of the saline-treated mice. In 1,2-dimethylhydrazine-treated mice the majority of ACF were present in the middle third of the colon, between the two peaks of GALT, but the majority of the tumors were found over the GALT in the distal colon. There was a significant positive linear regression relationship between the numerical distribution of GALT and the numerical distribution of tumors along the length of the large bowel. There was no significant relationship between the distribution of ACF and the distribution of (a) tumors or (b) GALT along the length of the large bowel. Thus the numerical density of lymphoid nodules, not the numbers or distribution of ACF, was the significant predictor of the distribution of tumors in the large bowel of 1,2-dimethylhydrazine-treated mice. It is proposed that lymphoid nodules in the distal large bowel play a promotional role following initiation of colon carcinogenesis and that ACF have little if any malignant potential in the mouse.

A 10-mG, 50 to 60-Hz magnetic field is in the intensity and frequency range that people worldwide are often exposed to in homes and in the workplace. Studies about the effects of 50- to 100-Hz electromagnetic fields on various species of animal embryos (fish, chick, fly, sea urchin, rat, and mouse) indicate that early stages of embryonic development are responsive to fluctuating magnetic fields. Chick, sea urchin, and mouse embryos are responsive to magnetic field intensities of 10-100 mG. Results from studies on sea urchin embryos indicate that exposure to conditions of rotating 60-Hz magnetic fields, e.g., similar to those in our environment, interferes with cell proliferation at the morula stage in a manner dependent on field intensity. The cleavage stages, prior to the 64-cell stage, were not delayed by this rotating 60-Hz magnetic field suggesting that the ionic surges, DNA replication, and translational events essential for early cleavage stages were not significantly altered. Studies of histone synthesis in early sea urchin embryos indicated that the rotating 60-Hz magnetic field decreased zygotic expression of "early" histone genes at the morula stage and suggests that this decrease in early histone production was limiting to cell proliferation. Whether these comparative observations from animal development studies will be paralleled by results from studies of human embryogenesis, as suggested by some epidemiology studies, has yet to be established.

Flash frozen samples of normal human blood were cryosectioned and cryodried for electron probe x-ray microanalysis of the concentration of ions and elements in individual erythrocytes (RBCs). The data (expressed in mM/kg dry weight) demonstrated a systematic pattern of variation between the concentration of ions and elements in the RBCs. Specifically as K+ and Cl- decreased in concentration, Ca2+ and sulfur increased in concentration. Phosphorous, Na+ and Mg2+ did not demonstrate a significant pattern of change. These findings are related to the dehydration and to the volume decrease that accompanies senescence of the RBC.

The effect of dietary supplementation with pectin and/or guar gum on 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis was studied using 120 male Sprague-Dawley rats. The rats were given a weekly injection of DMH for 8 weeks and were maintained on a basal fiber-free diet supplemented with 5% cellulose. The rats were then subdivided into four groups and kept on the basal fiber-free diet supplemented with either no fiber, 10% pectin, 10% guar gum or a combination of 5% pectin/5% guar gum for a period of 24 weeks. The 8 weeks of DMH administration were defined as the initiation stage of carcinogenesis and the next 24 weeks were defined as the promotional stage of carcinogenesis. Food and water were available ad libitum. The rats were killed 32 weeks after the start of the experiment and tumor incidence, location and frequency in the colon were determined. Other parameters measured were body weight and caloric intake. Dietary fiber supplementation with 10% pectin or with 10% guar gum but not with the combination of 5% pectin/5% guar gum (fed during the promotional stage of carcinogenesis), was found to suppress colon cancer incidence to a significant extent.

Seven-week-old Sprague-Dawley rats were fed a semipurified AIN76 diet and were given a weekly injection of the colon carcinogen 1,2-dimethylhydrazine for 8 weeks (initiation stage of carcinogenesis). The rats were divided into seven groups and each group of rats was placed on one of seven different modifications of the AIN76 diet for the next 24 weeks (promotional stage of carcinogenesis). The mean numbers of aberrant crypt foci/rat and the incidence of adenocarcinomas from some of the seven dietary groups were found to be significantly different. However, all attempts to show a significant correlation between the mean number of aberrant crypt foci/rat and the incidence of adenocarcinomas failed. Therefore, the number of aberrant crypt foci/rat cannot by itself be used as a reliable quantitative predictor (biomarker) of the efficacy of dietary intervention or of chemopreventive procedures on modulating the risk of developing colon cancer. This conclusion emphasizes the need for end point validation of potential cancer biomarkers before the biomarkers can be considered predictive of modulation of the risk for colon cancer.

This study was designed to test how extended exposure of lenses to sera with different ionic strengths influences the distribution of ions and water in the lens. Pig lenses were incubated in cold sera (0 degree C), which were adjusted to variable concentrations of NaCl, and their K+, Na+, Cl-, and water contents were measured. Incubation at 0 degree C inhibits active transport processes and thereby allows equilibration of the mobile ions and water. The hypothesis was that lens water content (volume) would follow the ion-induced protein changes predicted by a model derived from previous osmotic studies on proteins. As expected, exposure of the lens to cold caused a gain of sodium and a partial loss of potassium. However, the potassium concentration in the lens remained several fold higher than that in the bathing solution (about 41 vs. 1.8-4.6 mM/kg H2O), indicating that a portion of the potassium within the cold-exposed lens was not free to diffuse. That the water content of the lens showed a negative rather than a positive relationship with the concentration of NaCl within the lens was explained by the idea that an increase in NaCl within the lens (up to at least 250 mM/kg H2O) causes a decrease in the osmotically unresponsive water volume associated with lens proteins.

In this report we briefly review recent evidence which shows that a substantial proportion of intracellular K+ is "bound" or perturbed from the physicochemical properties expected in dilute aqueous solutions. In addition, we present evidence from electron probe x-ray microanalysis of thin cryosections of cells which indicates that the binding of K+ to anionic groups either carboxyl groups (HCO2) on proteins or to phosphate groups in creatine phosphate (CrP), in adenosine triphosphate, (ATP), in protein and in nucleic acids, are the main determinants of the maintenance of (as differentiated from the generated of) the well known intra- to extracellular K+ concentration difference. The collective evidence suggests that much of cellular K+ is reduced in its mobility and in its chemical activity due to association with negative charge groups (e.g. carboxyl and phosphates). This fact forces abandonment of the misleading assumption that the majority of intracellular K+ and other inorganic ions are as free as would be expected under ideal solution conditions. This realization should have far reaching consequences toward understanding transmembrane movement of water and solutes in cells.