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Biomedical subjects

J B Watkins

Publications and source records attributed to J B Watkins.

At least 37 records · Page 2Linked to original sources
PubMed1996

Minimal effect of acute experimental hepatitis induced by lipopolysaccharide/D-galactosamine on biotransformation in rats.

When administered with D-galactosamine, lipopolysaccharide endotoxins produce a good experimental animal model of hepatitis. This galactosamine plus endotoxin model has been used widely, but the acute effect of this fixed combination of two chemicals on hepatic and extrahepatic biotransformation has not been determined. Therefore, either 2 or 4 hr after a single intraperitoneal dose of 300 mg/kg galactosamine plus 30 micrograms/kg lipopolysaccharide was administered, serum, liver, kidney, intestine, and spleen were collected. Serum enzymes (alanine and aspartate aminotransferases, sorbitol dehydrogenase, and gamma-glutamyltranspeptidase) were elevated dramatically 2 and 4 hr after treatment. Cytochrome P450 monooxygenase activity toward benzo-[a]pyrene was increased in kidney 4 hr after treatment, whereas dealkylation of 7-methoxycoumarin or 7-ethoxyresorufin was unchanged in any tissue at either time point. An increase in UDP-glucuronosyltransferase activity toward 4-methylumbelliferone and 4-hydroxybiphenyl was noted in the intestine. Conjugation of 1-chloro-2,4-dinitrobenzene with glutathione was increased in intestine and spleen 2 hr after treatment. gamma-Glutamyltranspeptidase activity was unaltered in all tissues studied. Reduced glutathione concentrations were increased significantly by different amounts depending on which organs were studied 2 or 4 hr after treatment. These results indicate that galactosamine/lipopolysaccharide-induced liver injury is not accompanied by major effects on the examined biotransformation reactions.

Animals↗
PubMed1996

Hepatobiliary excretion of cysteinyl leukotrienes in three experimental models of acute hepatic injury.

The acute phase response to chemically-induced organ damage involves inflammation and the production of leukotrienes. The liver ordinarily takes up, metabolizes and excretes into bile cysteinyl leukotrienes, but the effect of hepatic injury on these processes is unknown. The hepatic uptake and biliary excretion of LTC4 was studied in male Sprague-Dawley rats after exposure to either streptozotocin (45 mg/kg iv 30 days before experimentation), estradiol-17 beta-valerate (1 mg/kg sc once a week for 3 weeks) or lipopolysaccharide/D-galactosamine (33 micrograms/ kg ip; 300 mg/kg ip at 6 h and 3 h, respectively, before experimentation). Acute liver injury is produced by these treatment paradigms. Glucose concentrations and activities of several marker enzymes in plasma were measured to demonstrate hepatic injury. Biliary excretion of 3H-LTC4 was similar to normal control rats in the three types of acute liver injury. Bile flow rates after 3H-LTC4 injection were reduced in lipopolysaccharide-pretreated rats and increased in estradiol-treated animals. Total biliary excretion of leukotrienes was not altered in any disease group. Thus, these models of acute hepatic injury do not appear to influence the hepatobiliary clearance of leukotrienes.

Animals↗
PubMed1995

Biotransformation in Egyptian spiny mouse Acomys cahirinus.

The activities of several representative biotransformation enzymes were determined in male and female spiny mouse tissues. Cytochrome P450 monooxygenase activity toward benzo(a)pyrene was significantly greater in female spiny mouse intestine than in males. Activity toward benzphetamine in both sexes was high in the liver, with little activity in the kidney and intestine. Sulfotransferase activity was high in kidney and intestine of female spiny mice but undetectable in the same tissues in males. Hepatic glutathione S-transferase activity towards 1-chloro-2,4-dinitrobenzene in females was significantly higher than in males. UDP-Glucuronosyltransferase activity toward 1-naphthol in both sexes in the kidney was significantly higher than hepatic and intestinal activity. Intestinal N-acetyltransferase activity towards 2-aminofluorene and beta-naphthylamine was significantly greater in females than males. No consistent relation appeared to exist between biotransformation activities in spiny mouse and those in other related rodent species.

2-Naphthylamine↗
PubMed1995

Minimal effects of two aldose reductase inhibitors, AL-1576 and AL-4114, after subacute topical-ocular dosing on xenobiotic biotransformation in rabbits.

Aldose reductase is believed to be involved in teh etiology of diabetic complications, including cataractogenesis, nephropathy, and neuropathy. AL-1576 and AL-4114, two spirohydantoin aldose reductase inhibitors, were specifically developed for prevention of diabetic cataractogenesis. This study has determined whether AL-1576 and AL-4114 are inducers of biotransformation by assaying the activities of some phase I and phase II enzymes in the liver, kidney, intestine, and five ocular tissues (cornea, lens, iris-ciliary body, retina, and choroid). The aldose reductase inhibitors were administered topically (the intended route for use in preventing cataractogenesis) in two concentrations (0.5 and 5.0%) each 3 times/day to both eyes of New Zealand white rabbits for 14 days. Lenticular aldose reductase activity was decreased by 30-75% by the aldose reductase inhibitors. Monooxygenase activity toward benzo(a)pyrene, ethoxyresorufin, and methoxycoumarin was not increased by AL-1576 or AL-4114 treatment in any tissue. Activities of 1-chloro-2,4-dinitrobenzene glutathione S-transferase, 2-naphthol sulfotransferase, and 1-naphthol UDP-glucuronosyltransferase were not significantly induced in the eight tissues. Clearly, ocular dosing with AL-4114 and AL-1576 for 14 days had little effect on hepatic, intestinal, and ocular biotransformation.

Administration, Topical↗
PubMed1994

Ontogeny of hepatobiliary secretion: role of glutathione.

The ontogeny of hepatic synthesis and biliary secretion of glutathione was characterized and correlated with hepatic gamma glutamyl transpeptidase, bile flow rate, biliary bile acids and amino acids in Sprague-Dawley rats at 18 days of gestation and postnatally at ages 7, 14, 21, 28 and 54 days. Bile was collected by bile duct cannulation under intraperitoneal anesthesia with nembutal/ketamine. Glutathione, gamma glutamyl transpeptidase and bile acids were analyzed enzymatically and amino acids by high-performance liquid chromatography using established methods. Hepatic glutathione was low in the fetus, but increased to approximate adult levels by 7 days postnatally (2.77 mumol/gm liver). Hepatic gamma glutamyl transpeptidase activity, high in the fetus, declined to adult levels by day 7 (0.03 mumol/mg protein). In contrast, significant efflux of glutathione and its constituent amino acids into bile did not occur until weaning (21 days of age). During weaning, there was a fivefold increase in the biliary glutathione and with a twofold increase in bile flow rate. Biliary bile acids concentration remained constant throughout development, with only a 30% to 50% increase in its secretion rate. The data suggest that the developmentally related increase in bile flow rate was principally a result of the increase in bile acid independent flow from 1.1 microliters/(min.100 gm body wt) in the suckling to 4.3 microliters/(min.100 gm body wt) in the post-weanling animal.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1993

Effect of sodium orthovanadate on the hepatobiliary clearance of rose bengal in streptozotocin-induced diabetic rats.

Sodium orthovanadate is known to promote glucose uptake in muscle and adipose tissues and has been suggested as a possible oral hypoglycemic agent. In addition, insulin-dependent diabetes has been shown to alter the hepatobiliary clearance of several drugs in rats. This study has determined whether orthovanadate, like insulin, can reverse diabetes-induced changes in the biliary excretion of endogenous bile acids and in the hepatobiliary clearance of rose bengal. Six groups of male Sprague-Dawley rats were used; normal, insulin-treated normal, vanadate-treated normal, diabetic, insulin-treated diabetic, and vanadate-treated diabetic. Diabetes was induced by injection of streptozotocin (45 mg/kg, i.v.). One week later, insulin (2-4 U/day, s.c.) and sodium orthovanadate (877 +/- 82 mumol/kg/day, p.o.) treatments were initiated. After 4 weeks, the clearance and biliary excretion of rose bengal (60 mumol/kg, i.v.) were determined for 3 hr. Bile flow rate, rose bengal excretion, and excretion of endogenous bile acids were unchanged in the two treated normal groups and in the insulin-treated diabetic rats. These parameters were increased in untreated diabetic and vanadate-treated diabetic rats as compared with normal. Pharmacokinetic analyses indicated that total and biliary clearances of rose bengal were increased in diabetic rats and that orthovanadate did not reverse these changes. However, liver weight and serum glucose concentrations were reduced by orthovanadate treatment. These data indicate that the oral insulinomimetic chemical sodium orthovanadate effectively reversed some, but not all, of the diabetes-induced alterations of hepatic function.

Animals↗
PubMed1993

Passive jejunal bile salt absorption alters the enterohepatic circulation in immature rats.

BACKGROUND: Developmental changes in passive bile salt absorption may alter the enterohepatic circulation. METHODS: 14-, 21-, and 40-day-old anesthetized male Sprague-Dawley rats were studied. Jejunum and ileum were isolated, cannulated, and injected or perfused with a taurocholate, [3H]taurocholate, and nonabsorbable marker solution. Bile was collected. RESULTS: Using bolus injection, jejunal taurocholate absorption rates and total taurocholate absorption were nonsaturable, linearly related to taurocholate dose, and decreased from 14 days (1.62 nmol.cm-1.min-1) to 21 days (1.05 nmol.cm-1.min-1) and 40 days (0.54 nmol.cm-1.min-1). While total taurocholate absorption decreased (14 days, 52.4%; 21 days, 43.7%; 40 days, 30.5%), hepatic taurocholate clearance increased (14 days, 18.2%; 21 days, 23.7%; 40 days, 37.3%). Hepatic taurocholate clearance was saturated only at 14 days. Using jejunal perfusion, total taurocholate absorption (14 days, 62.0%; 21 days, 43.1%; 40 days, 45.3%) and taurocholate absorption rate decreased with age (14 days, 941.13 nmol.cm-2.min-1 per micromole of taurocholate; 21 days, 411.28 nmol.cm-2.min-1 per micromole of taurocholate; 40 days, 334.50 nmol.cm-2.min-1 per micromole of taurocholate). CONCLUSIONS: Passive jejunal bile salt absorption and decreased hepatic bile salt clearance could account for the low intraluminal and high serum bile salt levels observed in immature animals and in human neonates.

Aging↗
PubMed1993

Neonatal cholestasis: developmental aspects and current concepts.

Cholestatic disorders in infancy present the pediatric gastroenterologist, clinical investigator, and basic scientist with a unique model to probe the interfaces between the development and expression of essential functional elements in the liver and the extrauterine environment. This article has addressed some of the developmental features that define the process of bile formation in the neonate. Specific areas that limit effective maintenance of the extrahepatic circulation or interrupt the transition from an intrauterine to an extrauterine environment, including infectious diseases or metabolic disorders, have been identified. One may anticipate that a greater understanding of those features that are central to the processes of hepatic regeneration, the structural organization of the liver, and the mechanisms of hepatic injury will continue to make this an exciting area of investigation.

Adult↗
PubMed1993

Olsalazine versus sulfasalazine in mild to moderate childhood ulcerative colitis: results of the Pediatric Gastroenterology Collaborative Research Group Clinical Trial.

The safety and efficacy of olsalazine sodium was compared to sulfasalazine over 3 months in a multicenter, randomized, double-blind study of 56 children with mild to moderate ulcerative colitis. Twenty-eight children received 30 mg/kg/day of olsalazine (maximum, 2 g/day) and 28 received 60 mg/kg/day of sulfasalazine (maximum, 4 g/day). Side effects were frequent in both groups. Eleven of 28 patients (39%) on olsalazine reported headache, nausea, vomiting, rash, pruritus, increased diarrhea, and/or fever. Thirteen of 28 on sulfasalazine (46%) reported similar side effects and/or neutropenia, and four patients had the drug stopped because of an adverse reaction. After 3 months, 11 of 28 (39%) on olsalazine were asymptomatic or clinically improved, compared to 22 of 28 (79%) on sulfasalazine (p = 0.006). In addition, 10 of 28 patients on olsalazine versus one on sulfasalazine required prednisone because of lack of response or worsening of colitis (p = 0.005). The dose of olsalazine used in this clinical trial was thought to be equivalent to a standard dose of sulfasalazine, but fewer patients on olsalazine improved and a greater number had progression of symptoms when compared to sulfasalazine. Although side effects were slightly less frequent for olsalazine, the number of patients was too small to detect a clinically significant difference.

Adolescent↗
PubMed1993

Chronic physical activity alters hepatobiliary excretory function in rats.

Recent studies have indicated that exercise causes alterations in the biotransformation of some xenobiotics and the clearances of antipyrine and [14C]aminopyrine. The present study has investigated whether chronic voluntary physical activity alters hepatobiliary excretory function by comparing the clearance and biliary excretion of model substrates for each of four carrier-mediated transport systems (anion, uncharged, bile acid and cation; n = 8 for each chemical in each group) in active and inactive female rats. The active rats had access to running wheels and voluntarily ran 11.2 +/- 0.68 km/day. The active rats were fed ad libitum, and ate 37% more food than weight-matched, restricted-fed sedentary control rats. Basal bile flow was 34% higher in active rats than in inactive rats, and excretion of bile acids, cholesterol and phospholipid were also increased. The biliary excretion and biliary clearance of the anion, indocyanine green, were elevated in active rats, although total clearance and serum concentrations were not different due to decreased non-biliary clearance. Serum elimination and total clearance of the uncharged substrate, ouabain, were elevated in the active rats, due entirely to increased nonbiliary clearance. Total clearance of the bile acid, taurocholate, was higher in active rats due to an increased biliary clearance. In contrast, there were no differences in either the biliary excretion or clearances of the cation, procainamide ethobromide, between the two groups of rats. Finally, no differences in volume of distribution or elimination half-life were noted between inactive and active rats for any of the substrates.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminopyrine↗
PubMed1992

Chronic physical activity: hepatic hypertrophy and increased total biotransformation enzyme activity.

Does chronic voluntary physical activity alter hepatic or intestinal capacities for xenobiotic biotransformation? This question was investigated by comparing biotransformation enzyme activities in liver and small intestine of active and sedentary rats. Male rats allowed unlimited access to a running wheel and fed ad lib. for 6 weeks were weight-matched to sedentary controls; the active rats ate 22% more food than the sedentary rats (P less than 0.05). Active rats ran 2.8 +/- 0.6 miles/day. Liver weights were higher in the active rats (11.2 +/- 0.2 vs 9.8 +/- 0.2 g; P less than 0.05), as were total liver protein, and liver microsomal and cytosolic protein (P less than 0.05). As a result of liver hypertrophy, the active rats showed higher total liver activity of several biotransformation enzymes, including 2-naphthol sulfotransferase, styrene oxide hydrolase, benzphetamine N-demethylase, ethacrynic acid glutathione S-transferase and morphine UDP-glucuronosyltransferase (P less than 0.05). In contrast, there was no detectable difference in total liver N-acetyltransferase activity toward p-aminobenzoic acid, 2-naphthylamine, and 2-amino-fluorene as well as, relative hepatic enzyme activity (expressed per g liver or per mg protein) and total and relative intestinal enzyme activity. We conclude that chronic voluntary physical activity, accompanied by an increased food intake, results in liver hypertrophy and potentially increases total hepatic capacity to biotransform certain xenobiotic chemicals.

Animals↗
PubMed1992

Uptake of taurocholate, a vecuronium-like organic cation, ORG 9426, and ouabain into carcinogen-induced diploid and polyploid hepatocytes obtained by centrifugal elutriation.

Bile acid uptake, an important function of differentiated hepatocytes, is decreased in hepatocellular carcinomas and gamma-glutamyltranspeptidase-positive, putatively preneoplastic hepatocytes. Whether hepatic uptake is also changed in carcinogen-induced diploid hepatocytes versus polyploid hepatocytes is unknown. The present study has determined whether the hepatic uptake of three model compounds, an anionic bile acid, an organic cation and a neutral organic compound, into diploid cells is different from that in polyploid hepatocytes. These two hepatocyte populations were separated from the parent freshly isolated hepatocyte suspension by centrifugal elutriation. Flow cytometric analysis indicated that the diploid fraction contained approximately 83% diploid cells and that the polyploid fraction had about 84% polyploid hepatocytes. Initial uptake velocity was determined for taurocholate (1-50 microM), ORG 9426 (20-400 microM), a vecuronium-like cation, and ouabain (20-500 microM). Apparent Km was not different between diploid and polyploid cells for the three tested substrates, whereas apparent Vmax was decreased in diploid hepatocytes for taurocholate and ouabain by 42 and 55%, respectively. There were no changes in the hepatic uptake of ORG 9426. These data indicate that uptake by the bile acid/multispecific carrier is compromised in carcinogen-induced diploid cells.

Androstanols↗
PubMed1992

Biotransformation in carcinogen-induced diploid and polyploid hepatocytes separated by centrifugal elutriation.

Biotransformation in carcinogen-induced diploid and polyploid hepatocytes was studied using isozyme-selective substrates for several enzyme pathways. Diploid hepatocytes were induced by partial hepatectomy, a single injection of diethylnitrosamine, and 4 weeks of 2-acetylaminofluorene (2-AAF) feeding. Then, after an additional 3-5 weeks on the control diet, diploid and polyploid hepatocytes were separated from freshly isolated hepatocytes by centrifugal elutriation. Benzo(a)pyrene hydroxylase, ethoxyresorufin O-deethylase, and methoxycoumarin O-demethylase activities were approximately 15-40% lower in the diploid hepatocyte fraction than in the polyploid cell fraction. Activities of 1-chloro-2,4-dinitrobenzene, glutathione S-transferase, 3-hydroxy-benzo(a)pyrene or 4-hydroxybiphenyl UDP-glucuronosyltransferase, and DT-diaphorase were not different in the two cell fractions. Determination of activity during the 2-AAF treatment indicated that 2-AAF increased 7-ethoxyresorufin O-deethylase and 3-hydroxybenzo(a)pyrene glucuronosyltransferase activities by 300 and 200%, respectively, in both the diploid and polyploid hepatocyte fractions. Administration of phenobarbital for 4 days at the end of the control diet period increased ethoxyresorufin and methoxycoumarin dealkylations by 2- and 4-fold, and 3-hydroxybenzo(a)pyrene glucuronidation and 1-chloro-2,4-dinitrobenzene conjugation with glutathione by 1.5- to 2-fold in both hepatocyte fractions. Slight increases in benzo(a)pyrene hydroxylation and 4-hydroxybiphenyl glucuronidation were also evident in diploid cells. Although there is a slight decrease in cytochrome P-450-dependent monooxygenase activities, these data indicate that carcinogen-induced diploid hepatocytes do not show the typical toxicant-resistant phenotype observed in preneoplastic hepatocytes of altered liver foci, which are characterized by large decreases in monooxygenase biotransformations as well as increased activities of several phase II enzymes. This finding is compatible with the hypothesis that 2-AAF-induced nonploidizing growth of diploid hepatocytes is caused by nontoxic mechanisms in the present experimental paradigm. In addition, carcinogen-induced diploid cells respond to phenobarbital in a manner similar to that of polyploid hepatocytes.

2-Acetylaminofluorene↗
PubMed1992

Long-term diabetes alters the hepatobiliary clearance of acetaminophen, bilirubin and digoxin.

The effect of insulin-dependent diabetes on hepatobiliary clearance of acetaminophen, bilirubin and digoxin was determined using Sprague-Dawley rats that were treated with a 45 mg/kg dose of streptozotocin 28 days before experimentation. Urinary excretion of acetaminophen was increased 280%, whereas biliary excretion was decreased 65% and total clearance was unchanged. Both steady-state volume of distribution and elimination half-life of acetaminophen were decreased in diabetic rats by 23 and 25%, respectively. Biliary excretion of glucuronide and sulfate conjugates was decreased by 75 and 50%, respectively, whereas parent acetaminophen excretion was unchanged. The glutathione conjugate was only detected in normal and insulin-treated rats; however, comparable levels of a cysteine conjugate were detected in bile of diabetic rats. Administration of insulin reversed the hyperglycemia and the changes in volume of distribution, elimination half-life and glutathione excretion. Other diabetes-induced alterations were unchanged. In contrast, digoxin plasma disappearance, volume of distribution and total clearance were significantly increased in diabetic rats, whereas the elimination half-life was decreased. Administration of insulin reversed the changes in serum disappearance and partially reversed the increased biliary excretion of digoxin. No differences were observed for the serum disappearance, glucuronidation or biliary excretion of bilirubin in diabetic vs. normal rats. These data indicate that insulin deficiency for 1 month can alter hepatic excretory function and the pharmacokinetics of commonly used drugs.

Acetaminophen↗
PubMed1991

Effect of microsomal enzyme inducing agents on hepatic biotransformation in cotton rats (Sigmodon hispidus): comparison to that in Sprague-Dawley rats.

1. Activities of several biotransformation enzymes were determined in male and female Sigmodon hispidus. Benzphetamine N-demethylase and glutathione S-transferases toward 1-chloro-2,4-dinitrobenzene and sulfobromophthalein were higher in male Sigmodon hispidus than the female animals. 2. The study also determined the effect of microsomal enzyme inducing agents on hepatic biotransformation in male Sigmodon hispidus. 3. Cytochrome P-450 concentration was similar in cotton and Sprague-Dawley rats, and was increased after phenobarbital, pregnenolone-16 alpha-carbonitrile, or 3-methylcholanthrene treatment. 4. Benzphetamine N-demethylase was 4-fold higher in Sigmodon hispidus and was induced by 75-100% after phenobarbital. 5. UDP-Glucuronosyltransferase toward estrone, 1-naphthol, diethylstilbestrol and testosterone was 2- to 4-fold higher in cotton rats and was not altered by treatment with the inducing agents. 6. Conjugation of 1-chloro-2,4-dinitrobenzene, ethacrynic acid and sulfobromophthalein with glutathione was similar in both rodent species and was not inducible. 7. Sulfation of 2-naphthol was 15-30% of that in Sprague-Dawley rats and was not increased by inducer administration.

Animals↗
PubMed1991

Comparison of nonabsorbable markers Poly R-478 and [14C]PEG-4,000 for use in developmental absorption studies.

To determine the utility of Poly R-478, a stable, polymeric dye (MW, 40,000), as a nonabsorbable marker for studies in the developing small intestine, it was validated by comparison to carbon 14-labeled polyethylene glycol, MW 4,000 [( 14C]PEG-4,000) in rats from 14 to 40 days of age. The recovery and quantification of Poly R-478 from biological samples is simple and rapid compared to other nonradioactive nonabsorbable markers. In 40-day-old rats simultaneously given Poly R-478 and [14C]PEG, total recoveries were similar, the percentages of the Poly R-478 dose and the [14C]PEG dose recovered per segment were identical, and taurocholate absorption rates calculated using each marker were comparable. Recovery of Poly R-478 from flushed intestinal segments, determined by a one-step extraction, was equivalent to that of [14C]PEG in 40-day-old rats (96.5 +/- 3.7% versus 102.7 +/- 10.1%; NS) but was superior to that of [14C]PEG in 21-day-old rats (98.0 +/- 6.2% versus 63.4 +/- 5.5%; p less than 0.001) and 14-day-old rats (97.8 +/- 6.7% versus 56.7 +/- 12.6%; p less than 0.001). Within each age group, the distribution of Poly R-478 within the intestine was similar to that of [14C]PEG. In addition, total taurocholate absorption in the presence of Poly R-478 was comparable to that in the presence of [14C]PEG. Complete recovery of Poly R-478 from a suspension of liver particles and from mixtures with two commercial infant formulas was demonstrated in vitro, suggesting that Poly R-478 may be used when foods are present in the intestine.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗