scholarly journals Phosphatidylcholine synthesis in the developing small intestine

1980 ◽  
Vol 186 (2) ◽  
pp. 399-403 ◽  
Author(s):  
P G Holtzapple ◽  
C M Starr ◽  
T Morck
Keyword(s):  
Small Intestine ◽  
Oleic Acid ◽  
Steady State ◽  
Adult Rats ◽  
Acyltransferase Activity ◽  
Acid Incorporation ◽  
Old Rats ◽  
Phosphatidylcholine Synthesis

1. Phosphatidylcholine synthesis in the foetal, newborn and adult small intestine of rats was studied by determination of cytidine diphosphocholine-1,2-diacylglycerocholine phosphotransferase (cholinephosphotransferase) and acyl-CoA-1-acyl-sn-glycerol-3-phosphocholine acyltransferase (lysophosphatidylcholine acyltransferase) activities and the incorporation of [1-14C]oleic acid into phosphatidylcholine. 2. Cholinephosphotransferase activity was low in foetal jejunum and ileum, increased 3-4 fold in the ileum by 6 days of age and by 12 days in the jejunum. Jejunal activity remained constant throughout weaning; ileal activity gradually decreased to values 25% of that of the jejunum. 3. Lysophosphatidylcholine acyltransferase activity was high in foetal jejunum and ileum, decreased 70% immediately after birth in the jejunum and increased to adult values by 12 days of age. Ileal activity decreased by 20% after birth, but decreased more rapidly at weaning to 30% of the activity in jejunum. 4. Initial rates and steady-state incorporation of [1-14C]oleic acid into phosphatidylcholine by jejunal rings of 10 day-old rats exceeded that observed in jejunal rings from adult rats by 2-4-fold. 5. In the postnatal jejunum, neither cholinephosphotransferase and lysophosphatidylcholine acyltransferase activities nor oleic acid incorporation were stimulated by cortisone administration in vivo.

scholarly journals In vitro analysis of the origin and maintenance of O-2Aadult progenitor cells.

1992 ◽  
Vol 116 (1) ◽  
pp. 167-176 ◽  
Author(s):  
D Wren ◽  
G Wolswijk ◽  
M Noble
Keyword(s):  
Adult Life ◽  
Cell Types ◽  
Adult Rats ◽  
Optic Nerves ◽  
Limited Life ◽  
Old Rats ◽  
Vitro Analysis

We have been studying the differing characteristics of oligodendrocyte-type-2 astrocyte (O-2A) progenitors isolated from optic nerves of perinatal and adult rats. These two cell types display striking differences in their in vitro phenotypes. In addition, the O-2Aperinatal progenitor population appears to have a limited life-span in vivo, while O-2Aadult progenitors appear to be maintained throughout life. O-2Aperinatal progenitors seem to have largely disappeared from the optic nerve by 1 mo after birth, and are not detectable in cultures derived from optic nerves of adult rats. In contrast, O-2Aadult progenitors can first be isolated from optic nerves of 7-d-old rats and are still present in optic nerves of 1-yr-old rats. These observations raise two questions: (a) From what source do O-2Aadult progenitors originate; and (b) how is the O-2Aadult progenitor population maintained in the nerve throughout life? We now provide in vitro evidence indicating that O-2Aadult progenitors are derived directly from a subpopulation of O-2Aperinatal progenitors. We also provide evidence indicating that O-2Aadult progenitors are capable of prolonged self renewal in vitro. In addition, our data suggests that the in vitro generation of oligodendrocytes from O-2Aadult progenitors occurs primarily through asymmetric division and differentiation, in contrast with the self-extinguishing pattern of symmetric division and differentiation displayed by O-2Aperinatal progenitors in vitro. We suggest that O-2Aadult progenitors express at least some properties of stem cells and thus may be able to support the generation of both differentiated progeny cells as well as their own continued replenishment throughout adult life.

scholarly journals Experimental model for in vivo determination of dietary fibre and its effect on the absorption of nutrients in the small intestine

1981 ◽  
Vol 45 (2) ◽  
pp. 283-294 ◽  
Author(s):  
Ann-Sofie Sandberg ◽  
H. Andersson ◽  
B. Hallgren ◽  
Kristina Hasselblad ◽  
B. Isaksson ◽  
...  
Keyword(s):  
Small Intestine ◽  
Wheat Bran ◽  
Dietary Fibre ◽  
Dry Weight ◽  
Direct Analysis ◽  
Fresh Weight ◽  
Wet Weight ◽  
Definition Of

1. An experimental model for the determination of dietary fibre according to the definition of Trowell et al. (1976) is described. Food was subjected to in vivo digestion in ileostomy patients, and the ileostomy contents were collected quantitatively, the polysaccharide components of which were analysed by gas–liquid chromatography and the Klason lignin by gravimetric determination. The model was used for the determination of dietary fibre in AACC (American Association of Cereal Chemists), wheat bran and for studies on the extent of hydrolysis of wheat-bran fibre in the stomach and small intestine. The effect of wheat bran on ileostomy losses of nitrogen, starch and electrolytes was also investigated.2. Nine patients with established ileostomies were studied during two periods while on a constant low-fibre diet. In the second period 16 g AACC wheat bran/d was added to the diet. The ileostomy contents and duplicate portions of the diet were subjected to determinations of wet weight, dry weight, water content, fibre components, starch, N, sodium and potassium.3. The wet weight of ileostomy contents increased by 94 g/24 h and dry weight by 10 g/24 h after consumption of bran. The dietary fibre of AACC bran, determined as the increase in polysaccharides and lignin of ileostomy contents after consumption of bran, was 280 g/kg fresh weight (310 g/kg dry matter). Direct analysis of polysaccharides and lignin in bran gave a value of 306 g/kg fresh weight. Of the added bran hemicellulose and cellulose 80–100% and 75–100% respectively were recovered in ileostomy contents. There was no significant difference between the two periods in amount of N, starch and K found in the ileostomy contents. The Na excretion increased during the ‘bran’ period and correlated well with the wet weight of ileostomy contents.4. In conclusion, it seems probable that determination of dietary fibre by in vivo digestion in ileostomy patients comes very close to the theoretical definition of dietary fibre, as the influence of bacteria in the ileum seems small. Bacterial growth should be avoided by using a technique involving the change of ileostomy bags every 2 h and immediate deep-freezing of the ileostomy contents. True dietary fibre can be determined by direct analysis of polysaccharides and lignin in the food, at least in bran. Very little digestion of hemicellulose and cellulose from bran occurs in the stomach and small bowel. The 10–20% loss in some patients may be due to digestion by the gastric juice or to bacterial fermentation in the ileum, or both. The extra amount of faecal N after consumption of bran, reported by others, is probably produced in the large bowel.

Measurement of leucine metabolism in man from a primed, continuous infusion of L-[1-3C]leucine

1980 ◽  
Vol 238 (5) ◽  
pp. E473-E479 ◽  
Author(s):  
D. E. Matthews ◽  
K. J. Motil ◽  
D. K. Rohrbaugh ◽  
J. F. Burke ◽  
V. R. Young ◽  
...  
Keyword(s):  
Steady State ◽  
Continuous Infusion ◽  
Co2 Production ◽  
Human Beings ◽  
Priming Dose ◽  
Leucine Metabolism ◽  
Kinetics Of ◽  
13Co2 Enrichment

Leucine metabolism in vivo can be determined from a primed, continuous infusion of L-[1-13C]leucine by measuring, at isotopic steady state, plasm [-13C]leucine enrichment, expired 13CO2 enrichment, and CO2 production rate. With an appropriate priming dose of L-[1-13C]leucine and NaH13CO3, isotopic steady state is reached in less than 2 h, and the infusion is completed in 4 h. The method can determine rates of leucine turnover, oxidation, and incorporation into protein with typical relative uncertainties of 2, 10, and 4%, respectively. The method requires no more than 1 ml of blood and uses stable isotope rather than radioisotope techniques. Thus, the method is applicable to studies of human beings of all ages. L-[1-13C]leucine may be infused with a second amino acid labeled with 15N for simultaneous determination of the kinetics of two amino acids.

Relation between dietary-induced increase of intestinal lactase activity and lactose digestion and absorption in adult rats

1984 ◽  
Vol 247 (6) ◽  
pp. G729-G735
Author(s):  
J. Leichter ◽  
T. Goda ◽  
S. D. Bhandari ◽  
S. Bustamante ◽  
O. Koldovsky
Keyword(s):  
Glucose Absorption ◽  
Diet Group ◽  
Lactase Activity ◽  
Weight Changes ◽  
Adult Rats ◽  
High Starch ◽  
Old Rats ◽  
Starch Diet

To study the relation between dietary-induced increase of intestinal lactase activity and lactose absorption, 11-wk-old rats were fed either a high-starch (70 cal%), low-fat (7 cal%) diet or a low-starch (5 cal%), high-fat (73 cal%) diet for 7 days. Food intake and body weight changes were similar in the two dietary groups. In the first experiment, lactose absorption was studied in vivo after oral administration of 600 mg lactose (10% solution in water with added [3H]PEG) to rats fasted for 16 h. Groups of rats were killed at time 0 and at 1-h intervals for the next 3 h. Lactase activity and lactose absorption were significantly higher (P less than 0.01) in the high-starch group than in the low-starch group. In the subsequent experiment, 9-wk-old rats were fed the two isocaloric diets for 3 days. By use of the everted sac technique, we have demonstrated a significantly higher absorption of monosaccharides from lactose in the high-starch diet group; also, glucose transport was higher in the high-starch diet-fed animals. When Tris, an inhibitor of lactase, was added into the mucosal fluid, absorption of lactose was abolished and no effect was seen on glucose absorption (in vivo and in vitro). In both experiments, significant linear regression was established between lactase activity and lactose absorption. Our results thus show that the increase in lactase activity, induced by feeding a high-starch diet to adult rats, is accompanied by an increased capacity to hydrolyze lactose and absorb the constituent monosaccharides.

scholarly journals Determination of steady-state protein breakdown rate in vivo by the disappearance of protein-bound tracer-labeled amino acids: a method applicable in humans

2013 ◽  
Vol 304 (8) ◽  
pp. E895-E907 ◽  
Author(s):  
Lars Holm ◽  
Bruce O'Rourke ◽  
David Ebenstein ◽  
Michael J. Toth ◽  
Rasmus Bechshoeft ◽  
...  
Keyword(s):  
Amino Acids ◽  
Steady State ◽  
Exponential Decay ◽  
Turnover Rate ◽  
Deuterium Oxide ◽  
Protein Breakdown ◽  
Breakdown Rate

A method to determine the rate of protein breakdown in individual proteins was developed and tested in rats and confirmed in humans, using administration of deuterium oxide and incorporation of the deuterium into alanine that was subsequently incorporated into body proteins. Measurement of the fractional breakdown rate of proteins was determined from the rate of disappearance of deuterated alanine from the proteins. The rate of disappearance of deuterated alanine from the proteins was calculated using an exponential decay, giving the fractional breakdown rate (FBR) of the proteins. The applicability of this protein-specific FBR approach is suitable for human in vivo experimentation. The labeling period of deuterium oxide administration is dependent on the turnover rate of the protein of interest.

In Vivo Determination of Hepatic Stiffness Using Steady-State Free Precession Magnetic Resonance Elastography

2006 ◽  
Vol 41 (12) ◽  
pp. 841-848 ◽  
Author(s):  
Dieter Klatt ◽  
Patrick Asbach ◽  
Jens Rump ◽  
Sebastian Papazoglou ◽  
Rajan Somasundaram ◽  
...  
Keyword(s):  
Steady State ◽  
Magnetic Resonance ◽  
Steady State Free Precession ◽  
Magnetic Resonance Elastography ◽  
Free Precession

Insulin resistance in older rats

1984 ◽  
Vol 246 (5) ◽  
pp. E397-E404 ◽  
Author(s):  
M. Narimiya ◽  
S. Azhar ◽  
C. B. Dolkas ◽  
C. E. Mondon ◽  
C. Sims ◽  
...  
Keyword(s):  
Steady State ◽  
Glucose Uptake ◽  
Soleus Muscle ◽  
Insulin Action ◽  
Glycogen Phosphorylase ◽  
Glycogen Synthase ◽  
Insulin Levels ◽  
Old Rats ◽  
State Plasma

Insulin-stimulated glucose utilization was estimated in vivo in 1.5-, 4-, and 12-mo-old rats with an insulin suppression test wherein the height of the steady-state plasma glucose ( SSPG ) concentration, at similar steady-state plasma insulin levels, provides a direct reflection of the efficiency of insulin-stimulated glucose disposal. In parallel studies, the effect of age on in vitro insulin-stimulated glucose uptake was assessed in perfused hindlimb preparations. In addition, changes in the activity of enzymes that regulate muscle glycolysis, glycogenesis, and glycogenolysis were determined in isolated soleus muscle. The results indicated that rats got heavier as they became older, and changes in weight were associated with parallel increases in mean (+/- SE) SSPG concentrations as rats grew from 1.5 (56 +/- 3 mg/dl) to 4 (172 +/- 6 mg/dl) to 12 mo of age (194 +/- 8 mg/dl). The age-related decline in in vivo insulin action was associated with a reduction in insulin action on muscle, and maximal insulin-stimulated glucose uptake by perfused hindlimbs of 12-mo-old rats was approximately 50% of the value seen with perfused hindlimbs from 1.5-mo-old rats. Soleus muscle enzyme activity also varied with age, with significant increases in glycogen synthase and decreases in glycogen phosphorylase documented. Furthermore, muscle glycogen phosphorylase activity, which fell during an insulin infusion in 1.5-mo-old rats, did not change when 12-mo-old rats were infused at comparable insulin levels. Finally, glycogen content was significantly increased (P less than 0.01) in soleus muscle from 12-mo-old rats.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Insulin resistance for glucose uptake and Akt2 phosphorylation in the soleus, but not epitrochlearis, muscles of old vs. adult rats

2010 ◽  
Vol 108 (6) ◽  
pp. 1631-1640 ◽  
Author(s):  
Naveen Sharma ◽  
Edward B. Arias ◽  
Mini P. Sajan ◽  
James G. MacKrell ◽  
Abhijit D. Bhat ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Glucose Uptake ◽  
Ex Vivo ◽  
Brown Norway ◽  
Adult Rats ◽  
Insulin Resistant ◽  
Age Related ◽  
Old Rats ◽  
Fast Twitch

The slow-twitch soleus, but not fast-twitch muscle, of old vs. adult rats has previously been demonstrated to become insulin resistant for in vivo glucose uptake. We probed cellular mechanisms for the age effect by assessing whether insulin resistance for glucose uptake was an intrinsic characteristic of the muscle ex vivo and by analyzing key insulin signaling steps. We hypothesized that isolated soleus and epitrochlearis (fast-twitch) muscles from old (25 mo) vs. adult (9 mo) male Fisher-344 × Brown Norway rats would have insulin resistance for Akt2 Thr308 phosphorylation (pAkt2Thr308), AS160 phosphorylation Thr642 (pAS160Thr642), and atypical PKC (aPKCζ/λ) activity corresponding in magnitude to the extent of insulin resistance for [3H]-2-deoxyglucose (2-DG) uptake. Epitrochlearis insulin-stimulated 2-DG uptake above basal values was unaltered by age, and epitrochlearis pAkt2Thr308, pAS160Thr642, and aPKCζ/λ activity were not significantly different in adult vs. old rats. Conversely, insulin-stimulated 2-DG uptake by the soleus of old vs. adult rats was reduced with 1.2 nM (42%) and 30 nM (28%) insulin concomitant with an age-related decline in pAkt2Thr308 of the insulin-stimulated soleus. There were no age effects on pAS160Thr642 or aPKCζ/λ activity or abundance of Akt2, AS160, GLUT4 or Appl1 protein in either muscle. The results suggest the possibility that an age-related decline in pAkt2Thr308, acting by a mechanism other than reduced pAS160Thr642, may play a role in the insulin resistance in the soleus of old rats. Skeletal muscle insulin resistance in old age is distinctive compared with other insulin-resistant rodent models that are not selective for greater insulin resistance in the soleus vs. the epitrochlearis.

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