Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.108 (lactase)
 2,133 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A model of nonischemic hypoxia of the jejunum was designed in dogs, by shunting of blood from the inferior vena cava directly into the regional mesenteric arterial supply, thereby lowering the PaO2 of the blood that reached the jejunal wall from 98.6 +/- 3 to 62 +/- 5 mm Hg. Absorption rates of sodium, glucose, fructose, glycine, and the dibasic aminoacid lysine were studied by in situ luminal perfusion of a 30-cm proximal jejunal segment with a bicarbonate buffer solution containing phenol red as a nonabsorbable marker for determination of water fluxes. During periods of control, hypoxia, and after discontinuation of the venoarterial admixture (recovery), effluent perfusate was collected and mucosal biopsies were obtained for assay of lactase, maltase and sucrase activity, mucosal ATPase activity and ATP content, and for light- and electron microscopic examination. Mesenteric supply with hypoxic blood was associated with a significant inhibition of Na+,K+-ATPase activity (p less than 0.001) and a rise in mucosal ATP content (p less than 0.05). There was a significant reduction in the absorption rates of sodium (p less than 0.001), glucose, and glycine (p less than 0.01), but no change in the transport of fructose and of lysine. Brush border enzymes were unaltered. The histological appearance of the mucosa remained normal throughout the experiment, but on electron microscopy a distinct swelling of the enterocyte mitochondria was noted during the hypoxia period.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of nonischemic hypoxia on jejunal mucosal structure and function: study of an experimental model in dogs. 294 46

Intestinal hydrolase activities were studied during postnatal development in the offspring of rats exposed to 20% ethanol during gestation; alcohol was withdrawn at birth. Controls received water during gestation. Sucrase, lactase, glucoamylase and aminopeptidase activities were determined 2 and 4 weeks after birth in the proximal jejunum. Offspring prenatally exposed to ethanol showed a deficit in body weight and lower aminopeptidase activity during the suckling period (2 weeks). These effects were reversible by 4 weeks when alcohol was withdrawn at birth. The prenatal exposure to ethanol did not change the pattern of sucrase maturation in the intestine of offsprings. The activities of lactase and glucoamylase were not modified following prenatal exposure to ethanol. In conclusion, exposure to ethanol during gestation caused decreased abilities for the intestine of the offspring to digest protein.
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PMID:Prenatal exposure to alcohol in rat: effect on intestinal enzymes in offspring. 311 99

1) Most humans, like other mammals, gradually lose the intestinal enzyme lactase after infancy and with it the ability to digest lactose, the principle sugar in milk. At some point in prehistory, a genetic mutation occurred and lactase activity persisted in a majority of the adult population of Northern and Central Europe. 2) Persistence of intestinal lactase, the uncommon trait worldwide, is inherited as a highly penetrant autosomal-dominant characteristic. Both types of progeny are almost equally common when one parent is a lactose maldigester and the other a lactose digester. 3) The incidence of lactose maldigestion is usually determined in adults by the administration in the fasting state of a 50-g dose of lactose in water, the equivalent of that in 1 L of milk. Measurement is made of either the subsequent rise in blood glucose or the appearance of additional hydrogen in the breath. It is also sometimes identified by measuring lactase activity directly in a biopsy sample from the jejunum. For children the test dose is reduced according to weight. Depending on the severity of the lactase deficiency and other factors, the test dose may result in abdominal distention, pain, and diarrhea. 4) The frequency of lactose maldigestion varies widely among populations but is high in nearly all but those of European origin. In North American adults lactose maldigestion is found in approximately 79% of Native Americans, 75% of blacks, 51% of Hispanics, and 21% of Caucasians. In Africa, Asia, and Latin America prevalence rates range from 15-100% depending on the population studied. 5) Whenever the lactose ingested exceeds the capacity of the intestinal lactase to split it into the simple sugars glucose and galactose, which are absorbed directly, it passes undigested to the large intestine. There it is fermented by the colonic flora, with short-chain fatty acids and hydrogen gas as major products. The gas produced can cause abdominal distention and pain and diarrhea may also result from the fermentation products. 6) Among individuals with incomplete lactose digestion, there is considerable variation in awareness of lactose intolerance and in the quantity of lactose that can be ingested without symptoms. A positive standard lactose test is not a reliable predictor of the ability of an individual to consume moderate amounts of milk and milk products without symptoms. In usual situations the quantity of lactose ingested at any one time is much less than in the lactose-tolerance test.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The acceptability of milk and milk products in populations with a high prevalence of lactose intolerance. 314 Jun 51

Twelve female Wistar rats, weaned at 21 days, were allocated in two groups: Lactose Group composed by six rats receiving a normal laboratory diet added with 25 g of lactose for each 100 g of final mixture, and the Saccharose Group that was fed with the same diet but with the lactose being replaced by saccharose in the same proportion; both groups were studied for 28 days. The rats were weighed at the beginning of the experiment and on the 7th, 14th, 21st and 28th days; the relative ingestion of water and diet was evaluated for each animal on the same days except for the first. During the observation period weight gain was significantly lower on the Lactose Group compared to the Saccharose Group, although this difference became less evident towards the end of the experiment. In the Lactose Group the diet ingestion was higher on the 21st and 28th days opposed to the water ingestion which was higher on the 7th and 14th days. The results here presented suggest that, in spite of the ontogenic fall of intestinal lactase in rats, these animals can, even after weaning, accommodate to high doses of dietary lactose, by using adaptative pathways which deserve further investigation.
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PMID:[Adaptation of rats, after weaning, to a diet with a high concentration of lactose. I. Evaluation of water and diet ingestion]. 314 67

Seventy-two hour starvation in neonatal rabbits was studied. Fasted animals received no feeds, only water every 8 h for 72 h. Fed animals were suckled by the dam. There was no difference in birth weight, serum albumin, blood urea nitrogen, electrolytes, or urine specific gravity between fed and fasted animals. Weight at 72 hr was less in fasted (p less than 0.01) than fed rabbits. Serum cortisol (p less than 0.05) and corticosterone (p less than 0.01) levels were higher in the fasted group. Proximal and distal small bowel homogenates had less DNA and protein (p less than 0.01) in the fasted group, but the protein/DNA ratio was the same in the proximal and distal small bowel homogenates from both groups. Sucrase (E.C.3.2.1.26) specific activity was significantly increased in proximal small bowel homogenates from the fasted group (p less than 0.01) but was the same in distal small bowel homogenates from both groups. Sucrase total activity per proximal segment was the same in fed and fasted animals but was significantly less per segment in distal small bowel homogenates from fasted animals. Alkaline phosphatase (E.C.3.1.3) total and specific activity was decreased in proximal (p less than 0.01) and distal (p less than 0.05) small bowel homogenates from the fasted group. Lactase (E.C.3.2.1.23) total activity was decreased in proximal and distal (p less than 0.01) small bowel homogenates from the fasted group but lactase specific activity was unchanged. Thus, a brief period of malnutrition in neonatal animals can result in a variety of regional functional changes in the gastrointestinal mucosa.
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PMID:Short-term malnutrition in neonatal rabbits. I. Brush border enzymes. 368 82

To determine whether zinc has a specific role on intestinal growth and function, three groups of male weanling Sprague-Dawley rats were fed a semipurified zinc-deficient diet: ad libitum fed group received powdered diet and water containing 25 ppm of zinc; force fed (ZN, ZD) groups were fed identical amounts of diet to the ad libitum fed group by intragastric infusion three times per day. The diets were aqueous suspensions made with either deionized water (ZD) or water containing 25 ppm of zinc (ZN), and additional drinking water with (ZN) or without zinc (ZD) was offered ad libitum. Rats were sacrificed after 8 days of feeding. The ZD group showed growth arrest, perioral and periorbital dermal lesions, and abdominal distention within 8 days of feeding. Mucosal DNA, protein, sucrase, maltase, lactase, leucine aminopeptidase, and alkaline phosphatase were significantly decreased in the ZD group, whereas intestinal length, weight, and mucosal weight were unaltered. These results suggest that short-term isolated zinc deficiency impairs growth, digestion, and absorption in the rat small intestine, even in the absence of associated protein calorie malnutrition.
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PMID:Effects of short-term isolated zinc deficiency on intestinal growth and activities of several brush border enzymes in weaning rats. 408 Apr 54

There was a significant depression of the activities of intestinal lactase, invertase, and alkaline phosphatase in rats given drinking water containing 2.5 mg of colchicine per 100 ml. Activities of intestinal maltase, aspartate transcarbamylase, and dihydroorotase were not affected by the drug. Injection of colchicine (1 mg/kg) caused depression of intestinal invertase activity within 8 hr. Investigation of the effect of colchicine on the disaccharides in vitro demonstrated that invertase and maltase were not affected by concentrations up to 125 mg/100 ml. Intestinal lactase was inhibited by concentrations exceeding 5 mg/100 ml. Calculation of the concentration of colchicine present in the intestine, after a single injection, indicated that the in vivo effect of colchicine was not due to simple enzyme inhibition. Histological examination showed an increase in crypt cells but no decrease in the length of the villi. Cellular migration along the villi, as well as activity of uridine kinase in intestinal mucosa, was increased in colchicine-treated rats. It was concluded that colchicine did not depress intestinal invertase, lactase, and alkaline phosphatase by decreasing cellular renewal, but rather it exerted its effect directly on the differentiated cells of the villus.
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PMID:Effect of colchicine on intestinal disaccharidases: correlation with biochemical aspects of cellular renewal. 541 79

Jaundice phototherapy is associated with a significant incidence of watery diarrhea. We have postulated that acute intestinal secretion, rather than malabsorption of dietary carbohydrate, is an effect of a photoproduct of bilirubin upon the intestinal mucosa. Because of major effect of phototherapy is the hepatic excretion of nonconjugated bilirubin, we investigated the effect of bilirubin on small intestinal function in the hamster in vivo. The entire small intestine was luminally perfused in vivo with solutions containing bilirubin (0.125 to 0.75 mmole/liter) and net water and sodium fluxes were measured. Control animals absorbed both water (J H2O(net) = 58.9 microliter/min/g) and sodium (J Na(net) = 4.55 microEq/min/g), but animals perfused with bilirubin (greater than or equal to 0.25 mmole/liter) exhibited secretion of water (J H2O(net) = -39.0--85.9) and sodium (J Na(net)=-9.91--18.24). The rate of water secretion was positively related to the concentration of bilirubin in the infusate (r=0.749; p less than 0.001). The concentration of bilirubin in ultrafiltrates of perfusate was likewise positively related to its concentration in the infusate (r = 0.844; p less than 0.001), indicating the potential importance of soluble forms of bilirubin in inducing secretion. Possible epithelial injury was studied by measuring the concentration of DNA in the perfusate and the activity of disaccharidases in postperfusion mucosa, and the possible role of cyclic adenosine monophosphate as a mediator of the secretory process was investigated by determining its concentration in postperfusion mucosa. Perfusion with 0.5 mM bilirubin, which produced significant secretion, did not cause loss of DNA (0.284 versus 0.244 mg/liter) or mucosal lactase activity (56 versus 53 units/g) or enhancement of cyclic adenosine monophosphate concentration (14.9 versus 14.12 pmoles/mg protein).
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PMID:The effect of bilirubin on the function of hamster small intestine. 626 58

Large quantities of yogurt are consumed by some lactase-deficient population groups. We used breath hydrogen measurements to determine whether lactase-deficient subjects absorbed lactose in yogurt better than lactose in milk. Ingestion of 18 g of lactose in yogurt resulted in only about one third as much hydrogen excretion as a similar load of lactose in milk or water, indicating a much better absorption of lactose in yogurt. Ingestion of yogurt also resulted in fewer reports of diarrhea or flatulence than did a similar quantity of lactose ingested in milk or a water solution. The enhanced absorption of lactose in yogurt appeared to result from the intraintestinal digestion of lactose by lactase released from the yogurt organisms. This autodigesting feature makes yogurt a well-tolerated source of milk for lactase-deficient persons and may explain the widespread consumption of yogurt by lactase-deficient population groups.
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PMID:Yogurt--an autodigesting source of lactose. 641 39

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.
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PMID:Relation between dietary-induced increase of intestinal lactase activity and lactose digestion and absorption in adult rats. 643 52


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