Metabolism and epigenetics of pancreatic cancer stem cells.

Pancreatic Cancer (PDA) is an aggressive malignancy characterized by early spread and a high mortality. Current studies suggest that a subpopulation of cells exist within tumors, cancer stem cell (CSC), which are capable of self-renewal and give rise to unique progeny which form the major neoplastic cellular component of tumors. While CSCs constitute a small cellular subpopulation within the tumor, their resistance to chemotherapy and radiation make them an important therapeutic target for eradication. Along with distinctive phenotypic properties, CSCs possess a unique metabolic plasticity allowing them to rapidly respond and adapt to environmental changes. These cells and their progeny also display a significantly altered epigenetic state with distinctive patterns of DNA methylation. Several mechanisms of cross-talk between epigenetic and metabolic pathways in PDA exist which ultimately contribute to the observed cellular plasticity and enhanced tumorigenesis. In this review we discuss various examples of this metabolic-epigenetic interplay and how it may constitute a new avenue for therapy specifically targeting CSCs in PDA.

Recurrence of hepatocellular carcinoma at surgical incision site: case series and review of literature.

First reported two decades ago, isolated incisional recurrence of hepatocellular carcinoma is an extremely rare clinical entity. We present two cases of recurrence: one recurring over 10 years after initial resection, and the second presenting with a port site recurrence 3.5 years following laparoscopic radiofrequency ablation. Clinical case presentation, including radiographical, pathological, laboratory and intraoperative images are reported, together with a review of the current literature surrounding this uncommon hepatocellular carcinoma presentation.

Effect of insoluble fiber supplementation applied at different ages on digestive organ weight and digestive enzymes of layer-strain poultry.

Two experiments were conducted to study effects of dietary insoluble fiber (IF) on digestive enzyme function in layer poultry. In Experiment 1, 8 wk old pullets were fed a control diet (Group C) or a diet (Group IF) supplemented with 1% IF (Arbocel RC). After 5 wk, 6 pullets per group were killed and organ samples collected. The remaining pullets in Group C were divided into two groups: half were fed the control diet (Group C) and half were given the IF diet (Group C-IF). Similarly, half the pullets in Group IF continued on the IF diet (Group IF) and half on the control diet (Group IF-C). At 10 wk, organ samples were collected. BW at wk 5 (IF, 1364.8 g; C, 1342.9 g) and 10 wk (IF, 1678.1 g; IF-C, 1630.5 g; C-IF, 1617.1 g; C, 1580.4 g) were not different. At wk 5, the relative proventricular weight (0.41 g/100 g BW) and activities of pepsin (75.3 pepsin units/g proventriculus/min) and pancreatic general proteolytic activity (GP) (122.9 µmol tyrosine produced/g tissue) were greater (P < 0.05) than those of Group C (proventricular relative weight, 0.36; pepsin activity, 70.6; GP activity, 94.3). At wk 10, relative weights of liver and gizzard of Group IF were heavier (P < 0.05) than other treatments; activities of pepsin, GP, trypsin and chymotrypsin of IF pullets were significantly greater than other treatments as was mRNA expression for pepsinogens A (25.9 vs. 22.9) and C (13.1 vs. 10.8). In Experiment 2, 19 wk old hens were fed a control diet or a diet containing 0.8% IF (Arbocel RC) for 12 wk. Final BW after 12 wk was not different (IF, 1919.4 g; C, 1902.1 g). Pancreatic GP activity was greater (P < 0.05) in Group IF hens than Group C at wk 12 (122.2 vs. 97.0 µmol tyrosine released/min/g tissue)) as was relative gizzard weight (1.32 vs 1.10 g/100 g BW). The significantly improved digestive organ weights and enzyme activities in IF pullets may contribute to an improvement in feed utilization.

Quantitative feed restriction or meal-feeding of broiler chicks alter functional development of enzymes for protein digestion.

1. Two experiments were performed on broiler chicks to determine the effect of either quantitative feed restriction (QFR) from 5 to 11 d of age or meal-feeding (MF) from d 5 to 17 on development of activity of enzymes associated with protein digestion. 2. Proteolytic activity of the proventriculus was reduced by QFR but unaffected by MF. 3. General proteolytic and carboxypeptidase A activities of the pancreas were reduced by QFR and MF. 4. Amino- and dipeptidase activities of the small intestine were increased by QFR. Dipeptidase activity was unaffected by MF. 5. Nitrogen retention of QFR chicks was lower immediately following feed restriction but not in the 2 weeks following return to ad libitum access to feed. 6. Feeding regimen alters functional development of the enzymes of protein digestion and may therefore influence growth rate of broilers.

Sulfate incorporation into organic bone matrix of the tibiotarsus of broiler chicks is reduced by excess dietary methionine.

Two experiments were conducted in broiler chicks to determine whether dietary imbalances of sulfur amino acids (SAA), vitamin A, or interactions between the two nutrients could influence organic bone matrix metabolism measured with L-[35S]-methionine. In the first experiment, in vivo incorporation of 35S into the tibiotarsal bone matrix of 2-wk-old birds was unaffected by vitamin A treatment of 10 and 100 times the requirement when compared with that of birds receiving recommended amounts of vitamin A. However, 35S incorporation was significantly reduced by increasing the SAA concentration of the diet to 1.5 times the requirement relative to lysine. In the second experiment, in vitro incorporation of 35S, derived from L-[35S]-methionine, into bone matrix was reduced in birds consuming a diet containing 1.5 times the methionine requirement relative to lysine (Diet HS) when compared with those receiving .75 (Diet LS), 1.0 (Diet NS), or 1.25 (Diet MS) times the requirement. Birds consuming Diet LS incorporated significantly more 35S into organic bone matrix than birds consuming the other three diets. Although the ratio of SAA to lysine was that recommended (.76:1), on a weight basis the concentration of SAA in diet NS was relatively high (11.48 g/kg diet) compared with the NRC (1984) recommendation of 9.3 g/kg diet. The results show that excess SAA can affect organic bone matrix metabolism and suggest that SAA may play a role in the etiology of tibial dyschondroplasia. They also indicate the importance of distinguishing between nutrient content of the diet expressed as a ratio and that expressed on a weight basis.

Weight of internal organs and carcase yield of early food restricted broilers broilers.

1. Effects of food restriction on growth rate and relative growth rates of supply organs (liver, heart, lungs and kidneys, digestive tract) and demand organs (breast, back, thighs, abdominal fat) of broiler chickens were studied. 2. Birds were restricted in intake to 50% (group FI 50) or 75% (group FI 75) of ad libitum from 5 to 11 d of age; all birds were fed ad libitum from 12 to 39 d of age. 3. Relative growth rates from 12 to 39 d of age of group FI 50 were higher (P < 0.05) than group FI 75 and control group. 4. No significant differences in food conversion ratio, carcase fat and abdominal fat between groups were observed. 5. At 12 d of age, relative weight of the empty digestive tract of group FI 50 was higher (P < 0.05) than that of the control group and group FI 75. 6. The increased weight of the empty digestive tract may have contributed to the ability of the chickens to achieve compensatory growth after the restriction period.

Quantitative SPECT for indium-111-labeled antibodies in the livers of beagle dogs.

Results are presented for SPECT computations of liver volumes and 111In-labeled antibody activities in the livers of eight normal beagle dogs. Administered activities ranged from 1 to 2 mCi. SPECT studies were acquired 1 day postinjection using a rotating gamma camera system with elliptical orbits in a 360-degree rotation (128 views, 15 sec/view, 64 x 64 matrices). Uniformity-corrected images were reconstructed by use of the circular harmonic transform algorithm with computer software developed in-house. Liver volumes and activities were computed from transverse slices, 1 pixel (6.25 mm) in thickness. Comparison of SPECT and autopsy data demonstrated that absolute values of percent differences between measured and computed liver volumes ranged from 1.0% to 7.2%. Absolute values of percent differences between autopsy data and computed 111In activities in the liver ranged from 2.3% to 7.5%. These results suggest that quantitative SPECT has the potential of becoming an important tool in clinical trials for determining activities and localization volumes of radiolabeled antibodies directly from radionuclide images.

Hypervitaminosis A and calcium-regulating hormones in the rat.

The effect of vitamin A on calcium-regulating hormones was studied in rats. A single oral dose of 30 mg retinol equivalents (RE) given to adult rats caused no change to serum biologically active parathyroid hormone (bioactive-PTH) concentrations. Bioactive-PTH secretion from rat thyroparathyroid gland complexes was not significantly altered after in vitro incubation with 1.18 X 10(-6) M retinol. Chronically intoxicated rats given 15 mg RE 3 times a week for 6 wk, showed higher osteoclast numbers and lower osteoid than controls. Serum bioactive-PTH was not detectable and serum 25-hydroxyvitamin D (25-OHD) (25.2 +/- 12.5 nmol/L) was significantly (P less than 0.03) lower than controls (43.3 +/- 3.1). In acutely intoxicated rats (60 mg RE/d for 2 d), serum bioactive-PTH levels were significantly lower (0.02 +/- 0.05 ng/ml, P less than 0.03) than in control animals (0.14 +/- 0.08). Lower doses of vitamin A, 7.5 mg RE 3 times a week for 3 wk, suppressed serum bioactive-PTH to undetectable levels but had no significant effect on serum 25-OHD. Serum calcium and 25-OHD levels were significantly lower in vitamin D-intoxicated rats given 7.5 mg RE 3 times a week (ca. 3.16 +/- 0.19 mmol/L; 25-OHD 599.7 +/- 110.6 nmol/L) than vitamin D-intoxicated controls (3.42 +/- 0.17; 789.3 +/- 17.7). These results suggest that hypervitaminosis A can alter the metabolism of calcium-regulating hormones.

Bioactive parathyroid hormone in the rat: effects of calcium and calcitriol.

Bioactive PTH was measured in Wistar rats under a variety of experimental conditions. The mean activity in normal rat sera was 0.17 +/- 0.12 ng/ml (expressed in terms of bovine PTH 1-34). Sera from animals reared on a vitamin D deficient diet showed a mean value of 0.46 +/- 0.24 ng/ml (P less than 0.01), whereas sera from animals with 1,25-dihydroxyvitamin D (1,25(OH)2D) deficiency had a mean activity of 0.62 +/- 0.23 ng/ml (P less than 0.01). Dietary calcium deficiency also resulted in high serum PTH levels (0.71 +/- 0.34 ng/ml, P less than 0.01) in spite of marked elevations of serum 1,25(OH)2D concentrations in these animals. A significant negative correlation was noted between serum calcium and bioactive PTH. Calcium infusions into hypocalcemic, vitamin D-deficient rats caused a fall in serum bioactive PTH concentrations to a mean of 13% of control values within 10 min. Intraperitoneal administration of 1,25(OH)2D3 to hypocalcemic, 1,25(OH)2D-deficient rats did not suppress serum bioactive PTH concentrations after 30 or 60 min even though serum 1,25(OH)2D concentrations were greater than 900 pmol/liter in each animal at these time points. To our knowledge, this is the first study using PTH bioassays for physiological experiments in rats.

The synthesis of vitamin D metabolites by human melanoma cells.

Two melanin-producing human melanoma cell lines originally established from fresh surgical specimens were incubated with 25 hydroxyvitamin D3 (25 OHD3). Both cell lines produced material comigrating with 1,25 dihydroxy-vitamin D3 (1,25(OH)2D3) and 24,25 dihydroxyvitamin D3 (24,25(OH)2D3) in straight and reverse phase high performance liquid chromatography systems and displacing the relevant labeled ligands in competitive binding assays. The material designated 1,25(OH)2D3 was found almost entirely within the cells, whereas 24,25(OH)2D3 was evenly distributed between cells and medium. The synthesis of dihydroxylated materials was time dependent and was not observed if the cells were boiled before incubation with 25 OHD3. Preincubation with 1,25(OH)2D3 caused an increase in the synthesis of 24,25(OH)2D3 and a decrease in the synthesis of 1,25(OH)2D3. Michaelis-Menten constant (Km) values were 1.4 X 10(-9) mol/liter 25 OHD3 for the 1-alpha-hydroxylase enzyme and 72 X 10(-9) mol/liter for 24-hydroxylase. These studies constitute further evidence for the extrarenal synthesis of 1,25(OH)2D3. The suppressibility of 1 alpha-hydroxylase by preincubation with 1,25(OH)2D3 suggests a regulatory function for this system in the skin.

Discourse devices used by language disordered children: a preliminary investigation.

Language-disordered children's use of two devices through which utterances are related to ongoing discourse, focus and substitution operations, were observed. Focus operations merely repeat, while substitutions repeat part but also alter a previous utterance in some way. Previous research with normal-language children shows that the predominant device a child uses changes developmentally, with focus operations more frequently used early and substitution operations emphasized later. The use of these devices was observed in the spontaneous conversations of three language-disordered children. Two were at a lower linguistic level (MLU's of 1.8 and 2.2) than the third (MLU 3.2). A developmental trend reflecting that of the normally developing children emerged. These results indicate that language-disordered children are not qualitatively different from normally developing children in their ability to use these particular devices for learning to participate in conversations.

The nutritional and metabolic impact of gamma-linolenic acid (18:3omega6) on cats deprived of animal lipid.

1. The syndrome induced by depriving cats of animal lipid is partially cured by feeding 18:3omega6. This is associated with an increase in levels of 20:3omega6, but not 20:4omega6, in plasma phospholipids. 2. It is concluded that the cat lacks delta5 desaturase activity and has a dietary requirement for 18:3omega6 and possible 20:4omega6.