Alan Medline

Effect of Short-Term Therapy with Propylthiouracil in Patients with Alcoholic Liver Disease

The effect of propylthiouracil (PTU; 300 mg/day) on alcoholic liver disease was evaluated in 133 patients in a short-term randomized double-blind trial. Severity of the disease was assessed by a composite clinical and laboratory index (CCLI). A normalization rate (NR) representing the rate of improvement in CCLI was calculated. Patients with alcoholic hepatitis, with and without cirrhosis, showed a significantly higher NR on PTU (43.6 +/- 4.6) than on placebo (19.8 +/- 3.3; P less than 0.001). A similar effect was observed in patients with abnormal prothrombin (no biopsy): NR was 32.9 +/- 6.9 on PTU and 2.6 +/- 3.7 on placebo (P less than 0.005). The effect of PTU on each clinical and laboratory component of the CCLI was also compared in these two groups. In 38 patients with alcoholic hepatitis and in 25 with abnormal prothrombin, those on PTU showed a greater improvement in 15 of 15 items (P less than 0.001) and 14 of 15 (P less than 0.01), respectively. When patients were divided according to the severity of the disease into those in the lower and upper halves of the CCLI range (81 and 52 patients, respectively), PTU was shown to have a significant effect only in the latter: The NR was 41.4 +/- 3.8 on PTU and 22.5 +/- 4.2 on placebo (P less than 0.005). PTU was ineffective in patients with inactive cirrhosis.

Effects of calcium and pH on the mucosal damage produced by deoxycholic acid in the rat colon.

A single pass perfusion system was used in anaesthetised, restrained rats to examine the effect of changing the composition of the perfusion fluid on the damage caused to the colonic epithelium by deoxycholic acid. Damage to the colonic surface was monitored with light microscopy, transmission and scanning electron microscopy and with measurements of deoxyribonucleic acid and carbohydrate in the perfusate. New scoring techniques for monitoring alterations in surface epithelium of light microscopy sections were used. The damaging effect of 5 mM deoxycholic acid to the colonic epithelium is inhibited by lowering the pH of the perfusion fluid from 7.9 to 5.5, or by increasing the calcium concentration from 0 to 4 mM. This inhibition is shown to be because of a decreased amount of bile acid in solution. Thus it is not the total concentration of deoxycholic acid in the colon that is responsible for the colonic damage, but the concentration in solution. Although extrapolation to the human situation must be made with caution, the concentration of bile acid in solution in the faecal water may be more relevant to colonic mucosal damage than total bile acid concentration.

Collagenisation of the Disse space in alcoholic liver disease.

Collagenisation of the space of Disse was systematically assessed to determine its relationship to the clinical and histological manifestations of chronic alcoholic liver disease. Ninety-four chronic alcoholics who had been submitted to biopsy were assessed by clinical manifestations of hepatic dysfunction and by a 17-parameter Combined Clinical and Laboratory Index (CCLI). Liver biopsies were scored for light (LM) and electron-microscopy (EM) abnormalities using a universal scoring system for both. Thirty-five patients with normal liver histology (LM) had an average collagen score of 0.6 +/- 0.1. Twelve cirrhotic patients and 29 with fatty liver, both groups with mild clinical manifestations, did not differ significantly. In 18 cirrhotic patients and five with fatty liver, both groups having severe clinical manifestations, the mean scores were 2.1 +/- 0.8 (P less than 0.02) and 2.5 +/- 0.6 (P less than 0.01) respectively. Collagenisation also correlated with CCLI (P less than 0.001), serum bilirubin (P less than 0.001), serum aspartate transferase (SGOT) (P less than 0.003), and clinical evidence of portal hypertension and histological changes of necrosis, inflammation, and terminal hepatic vein sclerosis. These results suggest that collagenisation of the Disse space may be important in the pathogenesis of alcoholic liver disease.

Effect of Maternal and Postweaning Folic Acid Supplementation on Mammary Tumor Risk in the Offspring

Intrauterine and early life exposure to folic acid has significantly increased in North America owing to folic acid fortification, widespread supplemental use, and periconceptional supplementation. We investigated the effects of maternal and postweaning folic acid supplementation on mammary tumor risk in the offspring. Female rats were placed on a control or folic acid-supplemented diet prior to mating and during pregnancy and lactation. At weaning, female pups from each maternal diet group were randomized to the control or supplemented diet and mammary tumors were induced with 7,12 dimethylbenz[a]anthracene at puberty. At necropsy, mammary tumor parameters, genomic DNA methylation, and DNA methyltransferase activity were determined in the offspring. Both maternal and postweaning folic acid supplementation significantly increased the risk of mammary adenocarcinomas in the offspring (OR = 2.1, 95% CI 1.2-3.8, P = 0.008 and OR = 1.9, 95% CI 1.1-3.3, P = 0.03, respectively). Maternal folic acid supplementation also significantly accelerated the rate of mammary adenocarcinoma appearance (P = 0.002) and increased the multiplicity of mammary adenocarcinomas (P = 0.008) in the offspring. Maternal, but not postweaning, folic acid supplementation significantly reduced global DNA methylation (P = 0.03), whereas postweaning, but not maternal, folic acid supplementation significantly decreased DNA methyltransferase activity (P = 0.05) in nonneoplastic mammary glands of the offspring. Our findings suggest that a high intrauterine and postweaning dietary exposure to folic acid may increase the risk of mammary tumors in the offspring. Further, they suggest that this tumor-promoting effect may be mediated in part by altered DNA methylation and DNMT activity.

Effect of maternal and postweaning folic acid supplementation on colorectal cancer risk in the offspring

Background Intrauterine and early life exposure to folic acid has significantly increased in North America owing to folic acid fortification, widespread supplemental use and periconceptional folic acid supplementation. The effect of maternal and postweaning folic acid supplementation on colorectal cancer risk in the offspring was investigated. Methods Female rats were placed on a control or supplemental (2.5× the control) diet prior to mating and during pregnancy and lactation. At weaning, male pups from each maternal diet group were randomised to the control or supplemental diet (n=55 per each of the four maternal/pup diet groups) for 31 weeks and colorectal cancer was induced by azoxymethane at 5 weeks of age. At necropsy, colorectal cancer parameters as well as colorectal epithelial proliferation, apoptosis and global DNA methylation were determined in the offspring. Results Maternal, but not postweaning, folic acid supplementation significantly reduced the odds of colorectal adenocarcinoma by 64% in the offspring (OR 0.36; 95% CI 0.18 to 0.71; p=0.003). Pups from the dams fed the control diet that were given postweaning folic acid supplementation had significantly higher tumour multiplicity and burden than other groups (p<0.05). Maternal and postweaning folic acid supplementation interacted in a manner that decreased rectal epithelial proliferation (p<0.05). Both maternal and postweaning folic acid supplementation significantly decreased DNA damage in the rectum (p<0.05). Maternal folic acid supplementation significantly increased (p=0.007), whereas postweaning supplementation significantly decreased (p<0.001), colorectal global DNA methylation. Conclusions The data suggest for the first time that maternal folic acid supplementation at the level equivalent to the average postfortification total folate intake in North America and to that recommended to women at reproductive age protects against the development of colorectal cancer in the offspring. This protective effect may be mediated in part by increased global DNA methylation and decreased epithelial proliferation and DNA damage in the colorectum.

Susceptibility of lean and obese Zucker rats to tumorigenesis induced by N-methyl-N-nitrosourea

To address the possible involvement of hyperinsulinemia in breast cancer development, we have examined the susceptibility of lean and obese Zucker rats to N-methyl-N-nitrosourea (MNU)-induced mammary cancer. Fifty-day-old female lean or obese Zucker rats received intraperitoneal (i.p.) injections of 37.5 or 20 mg/kg MNU, respectively. We showed in separate experiments that these doses produce similar levels of DNA methylation in the mammary epithelial cells of the lean and obese animals. Over the course of 29 weeks following MNU treatment, half of the lean rats developed carcinomas of the mammary gland, demonstrating that they are of intermediate susceptibility to mammary tumorigenesis. During this period, the obese rats developed hyperinsulinemia and insulin resistance as expected. Although palpable tumors developed at a similar rate in the lean and obese rats, only 10% of the obese animals developed mammary carcinomas. The obese rats, however, developed a high incidence (63.3%) of epidermal cysts that occurred mainly in the region of the mammary glands. A 13.3% incidence of colon carcinomas was also found in the obese rats. These results suggest that the development of hyperinsulinemia does not render the obese Zucker rats more susceptible to mammary gland carcinogenesis. Our observation of colon carcinomas in obese, but not lean rats, however, is consistent with evidence that hyperinsulinemia promotes colon cancer in rodents and humans.

Effect of folic acid supplementation on the progression of colorectal aberrant crypt foci

Whether or not folic acid supplementation promotes the progression of colorectal preneoplastic lesions to cancer is an important public health issue, given mandatory fortification and widespread supplemental use of folic acid in North America. We investigated the effect of folic acid supplementation on the progression of aberrant crypt foci (ACF), the earliest precursor of colorectal cancer. Male Sprague-Dawley rats (n = 152) were placed on a control diet (2 mg folic acid/kg diet) at weaning and ACF were induced by azoxymethane. Six weeks post-ACF induction, rats were randomized to receive 0, 2, 5 or 8 mg folic acid/kg diet. At 34 weeks of age, rats were killed, and colorectal tumor parameters, plasma folate and homocysteine (a sensitive inverse indicator of tissue folate status) concentrations and rectal epithelial proliferation were determined. Although the number of ACF increased as dietary folic acid levels increased (P = 0.015), the incidence of colorectal tumors did not differ significantly among the four dietary groups. However, tumor multiplicity was positively correlated with dietary folic acid levels (r = 0.32; P = 0.002) and inversely with plasma homocysteine concentrations (r = -0.32; P = 0.005). Tumor burden was positively correlated with dietary folic acid levels (r = 0.35; P = 0.001) and plasma folate concentrations (r = 0.33; P = 0.008) and inversely with plasma homocysteine concentrations (r = -0.42; P < 0.001). Rectal epithelial proliferation was positively correlated with dietary folic acid levels (r = 0.39; P < 0.001) and plasma folate concentrations (r = 0.34; P < 0.001) and inversely with plasma homocysteine concentrations (r = -0.37; P < 0.001). Our data suggest that folic acid supplementation may promote the progression of ACF to colorectal tumors.

Ultrastructure of Normal Rabbit Mesentery

The ultrastructure of the mesentery was examined by electron microscope (EM) after in vivo fixation in 7 normal rabbits. In 1, the fixation was performed after intravenous injection of an electron-dense tracer (iron dextran) and intraperitoneal infusion of dialysate 4.25% for 1 h. We studied morphometric data of what is considered to be the active peritoneal dialysis membrane, i.e. capillary endothelial cells, interstitium and mesothelial cells. The mesothelial cells are flattened and overlapping with tight junctions between them. They lie on a continuous basement membrane and they contain numerous intracytoplasmic vesicles, separated or in clusters. The mesenteric microvessels were mainly true capillaries of continuous type and postcapillary venules. Capillary lymphatics and larger lymphatic channels (lacunae) seem to be more extensive than the blood capillaries and venules. The endothelial cells contain many vesicles. The interstitium consists of bundles of collagen, fibroblasts and occasional macrophages. The electron-dense tracer was found in the vesicles of the mesothelial cells suggesting that vesicular transport may play an important part in the transportation of at least molecules of a certain size.

Thermally oxidized dietary fat and colon carcinogenesis in rodents

Thermally oxidized animal fat (beef tallow) was assessed for colon cancer-promoting and -initiating activity in F-344 rats and CF-1 mice with the use of the aberrant crypt focus (ACF) assay. In two promotion studies, extensively oxidized beef tallow (110 degrees C for 144-168 h, peroxide value approx 200 meq/kg, with > 80% loss of allylic and olefinic protons) had relatively little effect on the growth of ACF in F-344 rats. The multiplication constant for treatment/control of ACF size in aberrant crypts per ACF at 100 days was 1.07 (95% confidence interval = 1.01-1.14) and 0.98 (95% confidence interval = 0.91-1.06). ACF size was not affected by less extensively oxidized beef tallow or by a 10-fold reduction of dietary alpha-tocopherol during the growth of the ACF. In initiation studies, extensively oxidized beef tallow administered by gavage increased the number of animals with ACF and the number of ACF per colon (11 of 23 and 5 of 29 animals with ACF; 1.09 +/- 0.29 and 0.21 +/- 0.09 ACF/colon, respectively). Less severely oxidized beef tallow was without effect. Further studies with CF-1 mice confirmed that extensively oxidized beef tallow increased numbers of animals with ACF and average ACF per colon. The unsaturated aldehyde acrolein was without effect in the ACF assay. These data suggest that highly thermolyzed beef tallow contains an uncharacterized initiator or leads to conditions in which spontaneously initiated ACF are increased.

Effects of dietary folate on intestinal tumorigenesis in the APCMIN in mouse

Dietary folate appears to be inversely related to colorectal cancer risk. This study investigated the effects of dietary intervention with folate or the development of intestinal polyps in Min (Apc +/-) mice. Weanling Mil mice were fed diets containing 0, 2 (basal requirement), 8, or 20 mg folate/kg diet. At 3 and 6 months of dietary intervention, 50% of the mice from each group were sacrificed, and the small intestine and colon were analyzed for polyps and aberrant crypt foci (ACF). Serum folate concentrations accurately reflected dietary folate levels (P < 0.001). At 3 months no significant difference in the average number of total small intestinal polyps was observed among the four groups. However, increasing dietary folate levels significantly reduced the number of ileal, but not duodenal or jejunal, polyps in a dose-dependent manner (P-trend = 0.001); folate supplementation at 20 mg/kg diet was associated with a 68-78% reduction in the number of ileal polyps compared with the other three diets (P < 0.007). The number of ileal polyps was inversely correlated with serum folate concentrations (P = 0.03). At 3 months, increasing dietary folate levels significantly decreased the number of colonic ACF in a dose-dependent manner (P = 0.05); the control and two folate supplemented diets significantly reduced the number of colonic ACF by 75 100% compared with the folate-deficient diet (P < 0.04). The number of colonic ACF was inversely correlated with serum folate concentration (P = 0.05). No significant difference in the number of colonic adenoma was observed among the four groups at 3 months. At 6 months, no significant differences in the average number of total small intestinal, duodenal, and jejunal polyps, colonic adenomas, and colonic ACF wer observed among the four groups. However, the folate-deficient diet had 62-76% lower number of ileal polyps compared with the control and two folate-supplemented diets (P < 0.003). Serum folate concentrations, but not dietary folate levels, were directly correlated with the number of ilea polyps (P = 0.006). These data suggest that dietary folate supplementation suppresses the development of ileal polyps and colonic ACF in this model However, at later time points, folate supplementation appears to have an opposite effect on ileal polyps. These data generally support the role of folate in intestinal tumorigenesis suggested in epidemiological studies and chemical carcinogen animal models. Notwithstanding the limitations associated with this model, these data suggest that the optimal timing and dose of folate intervention need to be determined for safe and effective folate chemoprevention.