Effects of enteral infusion of hypertonic saline and nutrients on canine jejunal motor patterns

The aim of the study was to clarify the effects of hypertonic solutions on jejunal motility. The study focused on differential effects of hypertonic saline and nutrients. Motility of the canine proximal jejunum was recorded with closely spaced strain-gauge transducers. During fasting, hyperosmotic solutions (up to 1520 mosmol/liter) of saline or nutrients (1 kcal/ml) were infused into the proximal jejunum (0.5–1.5 ml/min) up to 6 hr. The hyperosmotic solutions stimulated jejunal motility. With both increasing osmolarity of saline or increasing energy load of nutrients, jejunal motility linearly declined. The reduction of motility was associated with a change in motor pattern from a propulsive to a more segmenting one. Hypertonic glucose evoked a significantly smaller level of motor activity compared with both saline (at given osmolarities) and an elemental diet (at given energy loads). Motility parameters were not different between glucose and maltose, although osmolarity of maltose was less than half (760 vs 1520 mosmol/liter). In contrast, a mixture of glucose-fructose exerted a smaller inhibition of jejunal motility than glucose. The hypertonic solutions of saline or nutrients were tolerated over 2 hr; with hypertonic saline retrograde power contractions with or without vomiting occurred, whereas with hypertonic nutrients vomiting was preceded by strong inhibition of jejunal motility. Three conclusions can be derived from the present results: (1) The behavior of jejunal motility suggested that the motor activity was the result of both a local stimulation and an inhibitory feedback mechanism. (2) The different degree of inhibition between glucose and saline indicated that the nutrient itself played a major role in the inhibitory feedback regulation, whereas osmolarity was of minor importance. (3) Comparisons between different nutrients suggested a linkage between inhibitory control of motility and the absorptive capacity of the gut for the single nutrient.     

Intestinal Absorption of Nutrients Is Not Influenced by Soy Fiber and Does Not Differ Between Oligomeric and Polymeric Enteral Diets

Enteric feeding is often associated withdiarrhea. To avoid this side effect, isoosmotic andfiber-supplemented enteral diets are recommended. Theaims of this study were to determine whethersupplementing enteral diets with soy fiber influencesnutrient absorption and whether in enteric feedingabsorption of nutrients and water fluxes differ betweenhyperosmotic oligomeric and isoosmotic polymeric diets. In mini pigs intestinal absorption and waterfluxes were measured by perfusing a 150-cm length ofjejunum. Six noncommercial iso- and hyperosmoticoligomeric and polymeric diets and six commercialpolymeric diets, either fiber-free or supplemented withsoy fiber, were used. Pancreatic enzymes were infusedconcomitantly with the polymeric diets. The absorptionof nutrients and energy did not differ between oligomeric and polymeric diets. Oligomericdiets of high energy density produced a pronouncedsecretion of water. Despite lower initial osmolality,polymeric diets produced a similar secretion of water due to rapid pancreatic hydrolysis.Supplementing diets with largely insoluble soy fiberincreased viscosity only between 4.6 and 14.5 mPa sec. Soy fiber did not influence absorption of nutrientsand energy and had also no effects on luminal transit andflow rate. The lack of effects was not due to dilutionof chyme by intestinal secretion of water because nodifferences existed between isoosmotic and hyperosmotic oligomeric diets. In conclusion, supplementingenteral diets with soy fiber does not impair theabsorption of nutrients. Enteric feeding with isoosmoticpolymeric diets provides no advantage compared with hyperosmotic oligomeric diets with respect toabsorption of nutrients and secretion ofwater.     

Comparison of absorption of nutrients and secretion of water between oligomeric and polymeric enteral diets in pigs

In patients who require enteric tube-feeding the osmolality of the formulas is assumed to play an important role. There is the dilemma that osmolality increases as the digestibility of formulas is enhanced by means of degradation of the nutrients. Hitherto there have been no reports of whether there are differences in nutrient absorption and water fluxes between iso-osmotic polymeric and hyperosmotic oligomeric diets. We therefore investigated absorption of nutrients and net fluxes of water during perfusion of a 1.5 m jejunal segment with oligomeric, polymeric and commercial oligopeptide diets either in the absence of pancreatic juice or with concomitant infusion of pancreatic enzymes. In the absence of pancreatic juice the absorption rates of the polymeric diet and the commercial oligopeptide diets reached 58.0 and 84.5% respectively of that of a completely-hydrolysed hyperosmotic oligomeric diet. The concomitant infusion of pancreatic enzymes with the polymeric and oligopeptide diets significantly increased the absorption rates of nutrients and energy. The highest absorption rate of energy occurred with the commercial formula Survimed (Fresenius, Bad Homburg, Germany), probably due to an optimal composition of the macronutrients. The increase in absorption due to the degradation of nutrients by pancreatic enzymes was associated with an increase in net water secretion and flow-rate, reaching similar values to those with the hyperosmotic oligomeric diet. It may be concluded that iso-osmotic oligopeptide formulas require further pancreatic hydrolysis for optimum absorption. In patients with normal pancreatic secretion, oligopeptide formulas have no advantage over polymeric diets. In patients with reduced pancreatic secretion, either completely-hydrolysed hyperosmotic oligomeric diets or polymeric diets supplemented with pancreatic enzymes are appropriate.     

Motor function of gastric antrum and pylorus for evacuation of low and high viscosity meals in dogs.

In five conscious dogs motility of the antrum, pyloric sphincter, and duodenum was recorded with strain gauge transducers and induction coils. Gastric evacuation of low, medium, and high viscosity meals was measured via a duodenal cannula and observed simultaneously by radiography. Computer analysis of the propagation of the gastric waves revealed increased velocity in the distal antrum but no simultaneous contractions of the terminal antrum and pyloric sphincter. Radiography showed, and measurements of the antral diameter confirmed, that the indentations of the gastric waves were significantly deeper with the low viscosity liquid meal compared with the medium and high viscosity meals. Thereby, retropulsion of the medium and high viscosity ingesta was produced. Results indicated that gastric evacuation was regulated predominantly by the depth of the peristaltic indentation, which depended on the viscosity of the gastric contents. Nothing indicated that the phasic contractions of the pyloric sphincter were of importance for the regulation of gastric emptying.     

EFFECT OF rhTGF-β1 AND rhGM-CSF ON RECEPTOR EXPRESSIONS IN J6-1 AND J6-2 LEUKEMIC CELLS

ABC immunoperoxidase was used to test the effects of rhTGF-β1 and rhGM-CSF on receptor expressions in J6-1 and J6-2 leukemic cell lines. Computer assisted image analysis system was introduced to evaluate positive index of time-and dose-dependent specimens. The expression of c-kit was elevated both in positive rate and positive index by TGF-01 in both time- and dose-dependent manners. Ing/ml rhTGF-β1 simultaneously enhanced the expression of c-fms and PDGF-R which is not detected in 50 ng / ml GM-CSF treatment. Endoglin was down-regulated after TGF-β treatment and up-regulated in J6-2 cells after GM-CSF treatment, c-kit Expression was elevated by TGF-β in J6-1 cells while decreased by both in J6-2 cells.     

Evaluation of a plasmid-based transgenic mouse model for detecting in vivo mutations

To study in vivo somatic mutations a C57BL/6 transgenic mousemodel was constructed harboring multiple chromosomally integratedcopies of the plasmid pUR288, which carried the lacZ reportergene as the mutational target. We previously demonstrated thatlacZ-containing plasmids could be rescued from their integratedstate efficient enough to detect mutations in lacZ by positiveselection. The smaller size of the plasmid vector, as comparedwith our earlier transgenic mouse model based on bacteriophagelambda vectors, should offer considerable advantages in termsof rescue efficiency and sensitivity to large size alterationsin the lacZ gene. To evaluate the plasmid-based mouse modelfor its suitability to detect in vivo mutations, we determinedmutant frequencies in different organs of untreated and ethylnitrosourea (ENU)-treated animals using a new, improved protocol.The rescue efficiencies obtained were as high as 200 000/µggenomic DNA; millions of transformants could be obtained inone single experiment. The average spontaneous mutant frequencyin four different organs of 4- to 8-week-old mice ranged from4.41 to 6.82x10^–5;, compared with a mutant frequency ofthe same plasmid grown in Escherichia coli of