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Biomedical subjects

R B Lu

Publications and source records attributed to R B Lu.

At least 37 records · Page 2Linked to original sources
PubMed1994

Effect of perfusion of oral rehydration solutions containing glucose polymers from corn on disaccharidases and mucosal morphology in rat small intestines.

This study aims to determine the effect of glucose and glucose polymers (GP) from corn in oral rehydration solutions (ORS) on disaccharidases and morphometric measurements in small intestinal mucosa of rats. ORS containing standard composition of salts as in WHO ORS and 2, 5, or 10 per cent glucose or GP [initial glucose polymers, long chain (> 9 molecules) and short chain (2-9 molecules) glucose polymers] from corn were infused into the duodenum of 72 Sprague-Dawley rats (250-350 g). Six rats were sham operated as controls. The levels of lactase, sucrase, maltase, palatinase, and glucoamylase enzymes were higher in rats infused with ORS-containing glucose or GP than control rats. Villus height, villus width, and crypt height in corresponding segments of duodenum, jejunum, and ileum were not significantly different between rats perfused with ORS containing glucose polymers from corn and those with ORS containing glucose. ORS containing GP from corn have no adverse effects on small intestinal enzymes and morphometric measurements.

Animals↗
PubMed1994

Maturational response of colonic and renal Na+,K(+)-ATPase activity to K+ load and betamethasone in preterm rats.

Preterm human infants demonstrate high fecal K+/Na+ ratio that is inversely related to maturation. Renal and colonic basolateral membrane-located Na+,K(+)-adenosine triphosphatase (Na+,K(+)-ATPase) governs K+ excretion and is enhanced by both steroid administration and K+ loading. However, the response of premature kidney or colon to these stimuli is not well studied. We measured basal as well as stimulated levels of renal and colonic Na+,K(+)-ATPase activity in response to betamethasone and K+ load given separately and betamethasone given after K+ load in premature, mature, and 4-day-old Sprague-Dawley rats. Although preterm rats showed a higher basal level in the kidneys (p < 0.004), an increase in enzyme activity in response to the stimuli was achieved only in the colon (p < 0.001 for betamethasone, p < 0.0001 for K+ load, and p < 0.0007 for the combination). At term and at 4 days of postnatal age, however, the kidneys showed much higher levels than the colon in response to stimuli (p < 0.0001 for all) except for betamethasone at term. The response of colonic tissue of preterm and term rats to betamethasone given 4 days after a K+ load was less marked than response to betamethasone or K+ load given separately (p < 0.001). The stimulated levels achieved in the preterm colon were higher than the basal preterm renal values (p < 0.001). The tissue K+ content increased in response to K+ load in only the preterm colon (p < 0.05). We have demonstrated a tissue specificity in the development of Na+,K(+)-ATPase activity in K+ excretory organs of rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1993

Absorption of glucose polymers from rice in oral rehydration solutions by rat small intestine.

BACKGROUND: This study aims to determine the effect of replacing glucose in oral rehydration solution (ORS) with starch hydrolysates from rice on absorption in the small intestine and levels of glucose in portal venous blood and on disaccharidase levels and morphometric measurements in intestines of rats. METHODS: ORS containing standard composition of salts and 2% glucose (WHO ORS) or 2%, 5%, or 10% starch hydrolysates were infused into duodena of 60 Sprague-Dawley rats (250-350 g). Portal venous blood glucose levels were determined at 0, 30, 60, 90, and 120 minutes. RESULTS: Significantly larger areas under the curve of glucose absorption (AUCs) were produced by ORS containing 10% unfractionated starch hydrolysates (123.2 +/- 3.8), 2%, 5%, and 10% starch hydrolysates with long-chain ( > 9 molecules) glucose polymers (109.5 +/- 10.6, 109.3 +/- 7.4, and 115.3 +/- 7.1, respectively), and 5% and 10% starch hydrolysates with short-chain (2-9 molecules) glucose polymers (124.4 +/- 6.1 and 128.1 +/- 6.8). ORS with 2% and 5% unfractionated starch hydrolysates and 2% short-chain glucose polymers produced AUCs comparable with those of WHO ORS (96.48 +/- 5.7). Disaccharidase levels and morphometric measurements were not significantly different. CONCLUSIONS: Starch hydrolysates from rice containing glucose polymers can be used in ORS in higher concentrations than glucose to provide higher caloric density without increased osmolality.

Animals↗
PubMed1993

Perinatal food restriction in rats reduces the content but not concentration of liver extracellular matrix proteins.

Fibrosis of the liver has been reported to be associated with malnutrition, based on qualitative histological and histochemical approaches. The aim of this study was to quantitatively examine the effect of perinatal food-restriction on the expression of extracellular matrix components of the liver, using rats fed 50% of ad libitum intake, determined by the food consumption of the control group on the previous day. Levels of extracellular matrix proteins were measured by dot blot analysis using monospecific antibodies against collagen types I, III and IV, laminin and fibronectin. The body weights of 4, 8 and 13-wk-old malnourished groups were 25, 35 and 48% of the control group body weights, respectively, and the liver weights were 22, 32 and 60% of the controls. The total contents of the extracellular matrix components were significantly reduced to 30, 34 and 58% of the controls, but when expressed per tissue or per milligram protein there were no significant differences. Indirect immunofluorescence revealed no major changes in extracellular matrix localization. The major histological change in the food-restricted rats was fatty infiltration. Our observations suggest that the effect of perinatal food restriction is mainly liver steatosis, and that the liver of food-restricted animals during the perinatal period has the capacity to preserve its main extracellular matrix components.

Animals↗
PubMed1993

The pre- and postnatal development of Na+/K(+)-ATPase in gastrointestinal organs of the rat: effect of betamethasone treatment.

Developmental changes in Na+/K(+)-ATPase enzyme activity have been documented postnatally in a number of organs, but little is known about prenatal levels or the factors affecting them. This study determined the normal developmental patterns of Na+/K(+)-ATPase activity in the pancreas, liver, small intestine, kidneys, and colon of pre- and postnatal rats. In addition the effect of betamethasone administration on enzyme activity was determined both antenatally and postnatally. The individual organs showed a variable pattern of maturational change in enzyme activity. In the pancreas, changes in Na+/K(+)-ATPase activity appeared to reflect the changing ratio of ductular to acinar cells. The pattern of enzyme activity in the small intestine was similar to that of the kidney and was inversely related to that of the colon. Enzyme induction by administration of betamethasone was also variable and bore no relationship to the DNA/protein ratio. In the preterm rat, betamethasone increased the Na+/K(+)-ATPase activity only in the colon. Use of steroids to increase enzyme activity in the colon at an early stage of development may have therapeutic implications for treating abnormalities of potassium and sodium homeostasis in the preterm infant.

Animals↗
PubMed1991

Essential role for polyamine biosynthesis in thyroxine stimulated pancreatic development in neonatal rats.

Administration of thyroxine to rat pups leads to precocious development of the pancreas. The role of ornithine decarboxylase (ODC) and polyamines in thyroxine-induced pancreatic maturation was examined. Rat pups (aged 5 days) were given daily subcutaneous injection of thyroxine (0.1 micrograms/g body wt.) until the day before death. Serial ODC activities were measured in pancreatic homogenates after 1, 2, 3, 4, 5, 6, 7 and 10 days of thyroxine treatment. There was a biphasic induction of ODC activities by thyroxine: an early peak appeared on day 2 of treatment followed by a decrease on day 4; a second peak was evident on day 5 and then a decrease to control values by day 7. Significant increases in tissue concentrations of putrescine and spermidine were observed concomitant with two peaks of ODC activity. Pancreatic amylase concentration, DNA and protein also showed a significant increase after thyroxine treatment. Difluoromethyl ornithine (DFMO), a specific ODC inhibitor, given orally (8% in drinking water) to nursing dams at postnatal day 5 for 5 days caused an 83% inhibition of pancreatic ODC activity in thyroxine-treated pups when compared to thyroxine-treated pups not exposed to DFMO. Concomitantly, the thyroxine-induced increases in pancreatic weight, protein and amylase activity were suppressed. Our results suggest that increases in ODC activities and polyamine levels are critical intermediary steps in the precocious induction of pancreatic development by thyroxine.

Amylases↗
PubMed1991

Short-chain glucose polymer and anthracene-9-carboxylic acid inhibit water and electrolyte secretion induced by dibutyryl cyclic AMP in the small intestine.

Glucose-stimulated sodium absorption is the rationale for treatment with glucose-based oral rehydration solution in diarrhea. Concurrent treatment with pharmacological inhibitors, which specifically block chloride secretion, may be a useful adjunct to oral fluid therapy. To examine this hypothesis, the authors determined the intestinal water and ion transport rates in rat small intestine during the secretory phase induced by perfusion with N6-2'-0-dibutyryl adenosine 3',5'-cyclic monophosphate (dbcAMP), 1.0 mmol/L. A marker (polyethylene glycol 4000) dilution technique was used to evaluate the antisecretory effects of a defined short-chain glucose polymer, D-glucose, and a chloride channel blocker, anthracene-9-carboxylic acid (A-9-C). The results showed that dbcAMP induced small intestinal water and chloride ion secretion rapidly and reliably. The 2.5% concentration of rice short glucose polymer (G2, 22.7%; G3, 28.2%; G4, 14.0%; G5, 16.6%; G6, 11.6%; G7-9, 6.9%) is a better carbohydrate than the 2.5% concentration of D-glucose in reversing secretion of water, chloride, and sodium ions induced by dbcAMP. The combination of A-9-C and the glucose polymer can reverse dbcAMP-induced intestinal secretion and produces significantly (P less than 0.05) better antisecretory effect on water, sodium, and chloride ions than D-glucose with A-9-C.

Animals↗
PubMed1991

Glucose polymers as an alternative to glucose in oral rehydration solutions.

Several issues involving glucose-based oral rehydration therapy may limit its acceptability and sustained use. Our studies suggest that defined short-chain glucose polymers (2 to 9 glucose units) are hydrolyzed and absorbed faster than isocaloric solutions of D-glucose in the small intestine of the rat. Glucose polymers, primarily from rice-based solutions, have been shown to be as effective as glucose-based solutions. They offer additional advantages in reducing the amount and duration of diarrhea with lesser volumes of solution, thereby reducing the costs of treatment. Rice-based solutions provide high caloric density and increase the absorption of sodium without an osmotic overload. The result is increased net absorption of glucose, sodium, and water. Glucose polymers from rice or other starches in oral rehydration solutions may be effective, inexpensive, easily used, and safe treatments for acute diarrhea.

Animals↗
PubMed1991

A new direct pancreatic function test in pediatrics.

Traditional methods for collecting duodenal fluid are time consuming and technically difficult. A simple endoscopic method is proposed in this report as a means of collecting duodenal fluid to perform exocrine pancreatic function tests. Thirty-five patients between 24 and 36 months of age were studied for pancreatic exocrine function. Twenty-seven presented with chronic diarrhea and 8 with failure to thrive. In 20 patients (group 1), duodenal fluid was collected by means of a double-lumen tube and sequential administration of pancreozymin (PZN) and secretin (SEC). The rest (group 2) had duodenal aspiration from the level of the papilla of Vater through a fiberoptic endoscope following administration of SEC only. The procedure took approximately 3 h in group 1 and 45 min in group 2. Secretin administration produced comparable levels of enzymes in both groups. Pancreozymin produced the highest enzyme levels, but this was only significantly higher than SEC-induced levels in the case of lipase. Endoscopic collection of duodenal fluid following SEC administration is a safe, quick, and reliable method of collecting pancreatic secretion.

Child, Preschool↗
PubMed1991

Alcohol and aldehyde dehydrogenase genotypes and alcoholism in Chinese men.

The liver enzymes alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), which are responsible for the oxidative metabolism of ethanol, are polymorphic in humans. An allele encoding an inactive form of the mitochondrial ALDH2 is known to reduce the likelihood of alcoholism in Japanese. We hypothesized that the polymorphisms of both ALDH and ADH modify the predisposition to development of alcoholism. Therefore, we determined the genotypes of the ADH2, ADH3, and ALDH2 loci of alcoholic and nonalcoholic Chinese men living in Taiwan, using leukocyte DNA amplified by the PCR and allele-specific oligonucleotides. The alcoholics had significantly lower frequencies of the ADH2*2, ADH3*1, and ALDH2*2 alleles than did the nonalcoholics, suggesting that genetic variation in both ADH and ALDH, by modulating the rate of metabolism of ethanol and acetaldehyde, influences drinking behavior and the risk of developing alcoholism.

Alcohol Dehydrogenase↗
PubMed1989

CSF neurochemical study of tardive dyskinesia.

Twenty-three inpatients who met DSM-III criteria for schizophrenia were selected for cerebrospinal fluid (CSF) neurochemical study of tardive dyskinesia (TD). Ten inpatients had tardive dyskinesia, and the remaining 13 patients without TD served as controls. There were no intergroup differences in sex, age, duration of neuroleptic treatment, or in total amount of neuroleptics received between the TD and the control groups. Cerebrospinal fluid was collected by lumbar puncture, and concentrations of homovanillic acid (HVA), MHPG, 5-hydroxyindoleacetic acid (5-HIAA), and acetylcholinesterase (AChE) activity were measured. The concentrations of MHPG (TD 11.56 +/- 3.48 ng/ml versus control 14.20 +/- 3.86 ng/ml), 5-HIAA (45.27 +/- 9.77 ng/ml versus 40.34 +/- 13.77 ng/ml), and HVA (38.26 +/- 18.31 ng/ml versus 31.40 +/- 7.83 ng/ml), and the activity of AChE (TD 7.95 +/- 5.21 mmol/g.hr versus control 12.89 +/- 8.04 mmol/g.hr) showed no significant differences between the two groups, but the ratios of HVA/AChE (t = 2.21, p = 0.05), 5-HIAA/AChE (t = 2.62, p = 0.02), MHPG/HVA (t = -2.16, p = 0.04), and MHPG/5-HIAA (t = -2.48, p = 0.02) were statistically different. The results indicated that TD might involve an imbalance of dopamine-acetylcholine, noradrenalin-dopamine, noradrenalin-serotonin, and serotonin-acetylcholine.

Acetylcholinesterase↗
PubMed1989

Response of exocrine pancreas to corticosterone and aldosterone after adrenalectomy.

The long-term effect of adrenalectomy (Adx) on the exocrine pancreas was examined in female adult rats. Pancreatic amylase concentration decrease to 50% of the control level starting 10 days after Adx, whereas the levels of trypsinogen and lipase remained unchanged. Replacement studies beginning 24 h after surgery with corticosterone (B, 1 mg/100 g body wt) or aldosterone (ALDO, 8 micrograms/100 g body wt) alone did not prevent the decline in amylase after Adx. However, when both hormones were administered together, pancreatic amylase concentration was maintained at a level similar to that of the control group. Serum corticosterone levels in the rats receiving B alone or B + ALDO were not different, and were comparable to levels found in normal rats. Both ALDO and B, given for 5 days starting 10 days after Adx, were required to restore amylase concentrations toward control values. When spironolactone (SPIRO, 3 mg/100 g body wt), a specific mineralocorticoid receptor blocker was administered bid together with ALDO + B, it blocked the increase in pancreatic amylase seen in ALDO + B treated rats but did not affect the serum corticosterone levels. These results suggest that mineralocorticoids are also involved in modulating the level of amylase in the rat exocrine pancreas.

Adrenal Glands↗
PubMed1988

Cortisol response to ACTH infusion in depressed patients: comparison with age-, sex-, and weight-matched normal subjects.

Adrenal responsiveness to Cosyntropin (synthetic ACTH) was investigated in five patients with major depression and five individually matched normal subjects. Three hours following suppression of endogenous ACTH secretion with dexamethasone (1 mg orally), the adrenal response to a 10-min infusion of Cosyntropin (0.05 micrograms/kg body weight) was monitored for 2 1/2 hr by plasma cortisol measured at 15-min intervals. The depressed patients had significantly higher baseline plasma cortisol, but not higher baseline ACTH, than the controls. During the 3-hr post-dexamethasone (and prior to Cosyntropin infusion), the depressed patients maintained significantly higher cortisol secretion, but not higher ACTH secretion, than the controls. After Cosyntropin infusion, there were no differences in ACTH and cortisol increases between the two groups. These findings stand in contrast to previous reports of enhanced adrenal responsiveness to the administration of much larger amounts of Cosyntropin in major depression.

Adrenocorticotropic Hormone↗
PubMed1988

The specificity of the dexamethasone suppression test in endogenous depressive patients.

The purpose of this study was to evaluate the specificity of the dexamethasone suppression test (DST) for endogenous depression. Between July 1983 and June 1985 we collected 51 cases of endogenous depression (including 16 bipolar disorder, depressed, and 35 major depression with melancholia), 36 cases of schizophrenia (including 14 with depression and 22 without depression), 19 cases of borderline disorder with depression, 16 cases of dysthymic disorder, and 20 normal volunteers. The sensitivity of the DST in the endogenous depression group was 62.7%, which was significantly higher than that of the schizophrenic group (36.1%), the borderline disorder with depression group (31.6%), and the control group (11.1%) (including dysthymic disorder patients and normal volunteers) (X2 = 24.48, df = 3, p less than 0.001). However, the specificity of the DST was 63.9%, 68.4%, and 88.9% when the endogenous depression group was compared with the other three groups, respectively. To differentiate endogenous depression from other mental disorders (e.g., schizophrenia, borderline disorder), such critical variables as patient history and clinical symptoms may be more valuable. Many factors that were reported to be related with DST were discussed.

Adult↗
PubMed1988

Thyroxine effect on exocrine pancreatic development in rats.

Thyroxine and glucocorticoids both play important roles in regulating the development of mammalian tissues. The mechanisms by which they modulate the developmental process is not fully understood. Furthermore, the interaction between the effects of two hormones on the pancreas has not been studied in detail. To investigate these issues, we studied the effect of thyroxine and/or corticosterone on the development of the exocrine pancreas in normal and adrenalectomized rats. Daily injection of thyroxine (0.1 micrograms/g body wt) to pups starting at day 5 of age resulted in precocious increases of exocrine enzymes in the pancreata of these pups. Hypothyroid pups, induced by propylthiouracil, exhibited suppression of development of their pancreatic exocrine enzymes. Replacement of thyroxine or corticosterone alleviated the suppression of exocrine enzyme development in these pups. Rat pups, who underwent adrenalectomy at 5 days of age, had undetectable plasma corticosterone and exhibited similar suppression of pancreatic enzyme development. Injection of thyroxine or corticosterone alone to adrenalectomized pups led to normal development of exocrine pancreatic enzymes. When both thyroxine and corticosterone were given together to adrenalectomized pups, their pancreatic enzyme levels were found to increase to values above those of pups treated with thyroxine or corticosterone alone. We conclude that thyroxine has both direct and indirect modulatory roles in the development of the rat exocrine pancreas. Normal development of the exocrine pancreas depends on both intact adrenal and thyroid function in the rat.

Adrenalectomy↗
PubMed1988

Regulation of rat pancreatic glucocorticoid receptors by thyroxine during development.

The effect of T4 on the development of pancreatic glucocorticoid receptors was studied in normal and adrenalectomized rat pups. Daily injection of T4 (0.1 microgram/g BW) to intact pups starting 3 days before death at 10, 15, and 20 days of age resulted in a precocious increase in pancreatic glucocorticoid-binding capacities. Intact pups made hypothyroid by propylthiouracil feeding exhibited lower glucocorticoid-binding capacities in their pancreata. Scatchard analysis demonstrated an increase in the number of glucocorticoid-binding sites in the pancreata of T4-treated intact rats compared to that in normal intact rats. In hypothyroid groups the number of glucocorticoid-binding sites was much lower than that in normal intact rats. The Kd values, however, were unchanged in hypothyroid, hyperthyroid, and control groups. Rat pups who underwent adrenalectomy at 12 days of age had undetectable plasma corticosterone levels and showed an increase in their pancreatic glucocorticoid-binding capacity 3 days after operation. Replacement of corticosterone resulted in a binding level similar to that in the sham-operated group. However, injection of T4 alone to adrenalectomized pups led to a further increase in pancreatic glucocorticoid-binding capacity above that due to adrenalectomy alone. When both T4 and corticosterone were given together to adrenalectomized pups their pancreatic glucocorticoid-binding capacities increased to levels above those in the adrenalectomized group, but lower than those in pups receiving T4 alone. Our results suggest that T4 modulates the development of rat pancreatic glucocorticoid receptors and, at least in part, acts via pathways independent of adrenal function.

Adrenalectomy↗