Venipuncture in the medical physiology laboratory

Medical physiology laboratories, traditionally devoted to animal experimentation, face unprecedented difficulties linked to cost, staffing, instrumentation, and the use of animals. At the same time, laboratory experiences with living creatures play a unique role in medical education. In this article we describe the use of venipuncture and subsequent blood analysis, with medical students serving as both subjects and experimenters, in a sequence of first-year physiology laboratories. These experiments are safe, robust, inexpensive, and time efficient, and they teach the principles of cardiovascular, respiratory, renal, nutritional, and gastrointestinal physiology. In addition, they enhance medical education in several other important dimensions. First, they teach safe venous blood collection and handling, a training appropriate for students at this level. Second, by serving each week as subjects as well as experimenters, students experience aspects of both sides of the doctor-patient relationship. Third, the laboratories can be used to teach fundamentals of research design and analysis. Finally, because blood analysis is central to medicine, and because the student's own blood data are discussed, students are enthusiastic and cooperative, and the clinical relevance of the data is clear.

Inhibition of WY-14,643 induced hepatic lesion growth in mice by rotenone

The effect of rotenone treatment on [4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio] acetic acid (WY-14,643) hepatic lesion growth in male B6C3F1 mice was investigated. Following induction of hepatic focal lesions by diethylnitrosamine (DEN) 35 mg/kg twice a week for 8 weeks, mice were placed into one of the four treatment groups: group I, control NIH-07 diet (control diet), group II, rotenone (600 mg/kg diet), group III NIH-07 diet containing WY-14,643 (1000 mg/kg diet), and group IV, NIH-07 diet containing WY-14,643 (1000 mg/kg diet) and rotenone (600 mg/ kg diet). Mice were killed after 30 and 60 days of dietary treatment. The effect of treatment with WY-14,643 and rotenone on hepatic lesion growth was examined by estimating the number of focal lesions per liver and the relative volume of focal lesions. WY-14,643 (group III) increased both the number and the volume of focal lesions. In particular, an increase in number and volume of basophilic lesions was seen. Co-treatment with WY-14,643 and rotenone (group IV) decreased both the number and the volume of the total number of focal lesions and basophilic foci compared with WY-14,643 treatment alone (group II). Alterations in the growth of hepatic focal lesions was further investigated by examining DNA synthesis and apoptosis within individual lesions. WY-14,643 (group III) treatment increased the DNA synthetic labeling index in all foci. Co-treatment of rotenone and WY-14,643 (group IV) decreased focal DNA synthesis and mitosis and increased the incidence of apoptotic hepatocytes. These data suggest that rotenone's ability to inhibit WY-14,643-induced hepatic focal lesion growth was mediated through a decrease in hepatic focal proliferation and an increase in focal apoptosis.

Hepatobiliary excretion of bile acids and rose bengal in streptozotocin-induced and genetic diabetic rats

Divergent opinions regarding the effect of streptozotocin- (STZ) induced diabetes on bile flow rate may be due to the differing lengths of time after STZ administration at which bile flow was measured. Also, the biliary excretion of bile acids can influence the canalicular transport of several organic anions. Therefore, the hepatic clearance of the bile acid-dependent organic anion rose bengal was studied over a 30-day period in STZ-induced insulin-dependent Sprague-Dawley diabetic rats with elevated bile acid pools and in fatty noninsulin-dependent diabetic and lean Wistar rats. Excretion of total bile acids and rose bengal was higher in diabetic rats than in Sprague-Dawley control or lean or fatty Wistar rats. Depletion of bile acids for 10 hr in the 30-day STZ rat prevented the increased excretion of rose bengal. Bile flow rates in fatty and lean Wistar rats were similar to that in Sprague-Dawley controls. Increased bile acid excretion 7 and 14 days after STZ was not accompanied by the expected significant increase in bile flow, reflecting decreased bile acid-independent bile flow, regardless of method of calculation of bile flow (per g liver or per kg body weight). By 30 days, there were significant increases in bile acid excretion and bile flow. The increased clearance of rose bengal 7 days after STZ indicates that pathophysiological changes in the hepatocyte begin soon after the initiation of diabetes. Studies of taurocholate uptake into liver plasma membrane vesicles indicated that the maximal velocity of transport across the basolateral membrane was increased with no change in Km. This change was not observed in vesicles from insulin-treated diabetic rats. Therefore, studies employing STZ need to allow time for STZ toxicity to be overcome and for the pathology of diabetes to become established, to accurately reflect the diabetic condition.

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.

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.

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.

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.

Chronic voluntary exercise may alter hepatobiliary clearance of endogenous and exogenous chemicals in rats

A chronic voluntary exercise paradigm, which mimics the exercise pattern of many humans, influences the hepatic clearance of several organic anions and a bile acid, whereas a neutral organic compound is seemingly unaffected. To extend these observations, the present work has evaluated in female Sprague-Dawley rats the effect of 6 weeks of voluntary running on the hepatobiliary elimination of endogenous bile acids and glutathione and exogenously injected rose bengal, digoxin, and acetaminophen. Inactive rats had mobility limited to their cages, whereas exercised rats had free access to a 44-in running wheel. In comparison to weight-matched sedentary rats, the exercised rats ran 4.3 +/- 0.3 miles/day, consumed 45% more food daily, had slightly greater liver/body weight ratios, and slightly elevated basal bile flow rates. Biliary excretion of endogenous bile acids was increased significantly, and excretion of reduced and oxidized glutathione was increased in exercised rats by 190% and 173% of sedentary levels, respectively. Total clearance, biliary clearance, and maximal biliary excretion of the injected organic anion rose bengal (60 mumol/kg) were elevated in exercised rats by 86%, 440%, and 85%, respectively. In contrast, there were no observed differences in pharmacokinetic parameters, serum elimination, or biliary excretion for the clinically important cardiac glycoside digoxin (dose of 100 nmol/kg). Finally, study of the analgesic acetaminophen (330 mumol/kg) revealed that total and biliary clearances were increased by 37% and 42%, respectively, in exercised rats, whereas steady-state volume of distribution and elimination half-life were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)

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)

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.

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.

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.

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)

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.

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.

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.

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.

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.

Comparative study of phase II biotransformation in rabbit ocular tissues

To assess the biotransformational capability of ocular tissues in the rabbit, representative phase II enzymes were assayed in five tissues from the eye, and in the liver, kidney, and intestine. Within the eye, the iris/ciliary body exhibited the highest glutathione S-transferase activity, whereas the cornea possessed the highest specific activities for N-acetyl-, sulfo-, and UDP-glucuronosyl-transferases. Cornea, iris/ciliary body, choroid, and retina exhibited significant activities of p-aminobenzoic acid N-acetyltransferase, 2-naphthol sulfotransferase, and 1-chloro-2,4-dinitrobenzene glutathione S-transferase. Despite its size and protein content, lens displayed little or no biotransformational activity. Only the iris/ciliary body conjugated sulfobromophthalein with glutathione. UDP-glucuronsyltransferase activity varied depending on tested substrates and tissues. When compared to liver, kidney, or intestine, N-acetyltransferase activity in the iris/ciliary body nearly matched the rate measured in kidney, glutathione S-transferase activity in cornea and iris/ciliary body was nearly 70 and 89%, respectively, of the rate in intestine, and corneal sulfotransferase activity was greater than that in kidney. These data suggest that biotransformation pathways are present in the eye, and particularly in ocular tissues having adequate blood supply or interfacing with the external environment.

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)

Effect of volatile anesthetics on the hepatic UDP-glucuronic acid pathway in mice

Large, rapid decreases in hepatic UDP-glucuronic acid concentrations occur in rats following exposure to myriad chemicals. In fact, 80% reductions in UDP-glucuronic acid occur within minutes after exposure to inhalation anesthetics. The present study was designed to determine whether this decrease in hepatic UDP-glucuronic acid may be due to (a) a decrease in the precursor UDP-glucose; (b) decreased activity of UDP-glucose dehydrogenase, which oxidizes UDP-glucose to UDP-glucuronic acid; (c) increased activity of UDP-glucuronosyltransferases; or (d) increased activity of nucleotide pryophosphatase, which degrades UDP-glucuronic acid to glucuronic acid-1-phosphate. Exposure to halothane, isoflurane and sevoflurane decreased UDP-glucuronic acid concentrations by 40-52% as compared to that in unanesthetized control mice. No sex-dependent or anesthetic-induced effects of UDP-glucose levels and the activities of UDP-glucose dehydrogenase and UDP-glucuronosyltransferase were observed. Nucleotide pyrophosphatase activity was increased by 47-65% in female mice after inhalation of halothane, isoflurane and sevoflurane. The apparent Vmax for hydrolysis of 4-nitrophenol thymidine 5'-monophosphate ester by nucleotide pyrophosphatase was increased by 56-80% in female mice, whereas the apparent Km was unchanged. These alterations in nucleotide pyrophosphate kinetics may be responsible, in part, for the marked decrease of hepatic UDP-glucuronic acid concentrations by the volatile anesthetics.

Procedural compliance and clinical outcome associated with therapeutic interchange of extended-spectrum penicillins

The degree of procedural compliance and the clinical outcome associated with a therapeutic interchange of extended-spectrum penicillins were assessed. Pharmacists conducted a concurrent chart review on all patients receiving mezlocillin as a therapeutic alternative for piperacillin or ticarcillin over a five-month period. The pharmacists assessed whether (1) the pharmacy appropriately dispensed mezlocillin when orders were written for piperacillin or ticarcillin, (2) physicians and nurses were properly notified of the therapeutic interchange, and (3) the bacterial isolates were susceptible to mezlocillin. Pharmacists and physicians evaluated clinical outcomes of all patients receiving mezlocillin through a retrospective chart review and classified the responses as "success," "failure," or "indeterminate." Fifty-one orders for piperacillin were written during the study period, and mezlocillin was selected as a therapeutic alternative in all cases. No orders for ticarcillin were written. Proper notification was made to nurses and physicians in 98% and 65% of cases, respectively. No mezlocillin-resistant gram-negative bacteria were found. Eighty-three courses of therapy were reviewed for clinical outcome; 68 were classified as successes, 0 were failures, and 15 were indeterminate. The cost savings after nine months of therapeutic interchange of mezlocillin for piperacillin was $6600. This study indicates that the pharmacy made a proper therapeutic interchange of mezlocillin for piperacillin and followed the correct procedure for notification of the nursing staff. However, more effort is needed to ensure communication with the prescribing physicians.

Taurocholate transport by brush-border membrane vesicles from the developing rabbit ileum: structure/function relationships

To examine the ontogenesis of bile acid transport in the rabbit ileum, brush-border membrane vesicles (12- to 20-fold purified) were prepared from 14- to 49-day-old animals. Taurocholate uptake was characterized by the emergence of secondary active, Na(+)-dependent transport at the start of weaning (21 days). Transient intravesicular accumulation (overshoot) of taurocholate occurred at 5-10 s of incubation, and the overshoot maximum increased significantly from 21 days (349.2 +/- 22.4 nmol/mg protein) to 35 days (569.0 +/- 84.3 nmol/mg protein; p less than 0.001), without further increase at maturity (49 days, not equal to 607.6 +/- 136.7 nmol/mg protein). No significant taurocholate active uptake component was noted at 14 days; however, ileal vesicles from sucklings showed carrier-mediated, Na+ D-glucose cotransport. In greater than or equal to 35-day-old rabbits, osmolarity studies at 20 s of incubation showed that only approximately 12% of [14C]taurocholate uptake was secondary to bile acid-to-membrane binding. Conversely, at 20 min, greater than 95% of radiolabel incorporation represented solute bound to the external and/or internal membrane surface. Arrhenius plots establish brush-border membrane taurocholate uptake as an intrinsic, lipid-dependent process, with a slope discontinuity between 24 and 28 degrees C, similar to the membrane lipid thermotropic transition region. Steady-state fluorescence polarization studies (1,6-diphenyl-1,3,5-hexatriene) demonstrate a temporal association between the maturation of taurocholate uptake and age-related decreases in ileal brush-border membrane fluidity. These data indicate that maturation of bile acid secondary active transport in the rabbit ileum may be regulated, at least in part, by changes in brush-border membrane lipid dynamics.

Role of nucleotide pyrophosphatase in enflurane-induced reduction of UDP-glucuronic acid concentration in mouse liver

Because hepatic UDP-glucuronic acid levels decrease upon exposure to volatile anesthetics, the present study was designed to determine the mechanism by which enflurane decreases UDP-glucuronic acid in mice by measuring the concentrations of intermediates and the activities of enzymes in the UDP-glucuronic acid pathway. UDP-glucuronic acid concentrations were decreased by 40% in both male and female mice after 10 min of enflurane-induced narcosis. Concentration of UDP-glucose and the activities of diethylstilbestrol UDP-glucuronosyltransferase and UDP-glucose dehydrogenase were not affected by enflurane treatment. In contrast, nucleotide pyrophophatase activity was increased approximately 50% in both sexes. Thus, the decrease in hepatic UDP-glucuronic acid upon exposure of mice to enflurane is probably due to increased degradation by nucleotide pyrophosphatase.

Skeletal muscle in the diabetic mouse: histochemical and morphometric analysis

Despite the extensive literature concerning the neuropathy associated with diabetes, only limited information describes changes in the associated muscle. The objective of this study was to evaluate the histochemical and morphometric characteristics of diabetic muscle in the C57BL/KsJ db-m strain of mouse. The histochemical analysis of myofiber type for the diabetic mouse revealed that the extensor digitorum longus muscle consisted of 53.1% type 2a, 46.0% type 2b, and 0.9% type 1 myofibers, a significant shift from the percentages found in the nondiabetic litter mates (44.4% type 2a, 55.6% type 2b, no type 1). Computer-assisted morphometric analysis of myofiber size by fiber type indicated a significant difference in myofiber size for the type 2b fibers in muscles from diabetic mice. Similarly, there was a shift in the fiber size distribution to include a greater number of small type 2b myofibers when compared to controls. Skeletal muscle from diabetic mice exhibited a significant change in the percentage of fiber types, with an increase in the number of type 2a fibers, a fiber type grouping that implies possible denervation and reinnervation, and a decrease in myofiber size. These findings may explain why some diabetic patients complain of muscle weakness.

Exposure of rats to inhalational anesthetics alters the hepatobiliary clearance of cholephilic xenobiotics

Several recent studies indicate that anesthesia-induced alteration of UDP-glucuronic acid concentrations can affect the rate of xenobiotic glucuronidation by UDP-glucuronosyltransferases. Other data demonstrate that the biliary excretion of several cholephilic drugs is depressed in rats anesthetized with diethyl ether. The present study has examined the effect of 2% halothane, 1.5% isoflurane, 2% enflurane and 3% sevoflurane on the clearance and biliary excretion of acetaminophen, digoxin, phenol red and phenol-3,6-dibromphthalein disulfonate. All volatile anesthetics reduced hepatic UDP-glucuronic acid concentrations 50 to 75%. Biliary excretion of acetaminophen as well as the glucuronide and sulfate conjugates was depressed by all anesthetics for about 1 hr, whereas biliary excretion of the glutathione conjugate was increased during this time. Although total clearance, elimination half-life and steady-state volume of distribution were not altered, biliary clearance of acetaminophen was decreased by 39 to 50%. Formation of the glucuronide conjugate of phenol red and its biliary excretion were depressed by all volatile anesthetics; however, total clearance was increased by 15 to 25% during isoflurane or sevoflurane anesthesia. Total clearance and steady-state volume of distribution of digoxin were decreased only in rats exposed to halothane. There were no changes in biliary excretion. Urinary clearance of digoxin was increased by all volatile anesthetics, whereas biliary clearance was decreased by halothane and enflurane. Biliary excretion, clearance and volume of distribution of phenol-3,6-dibromphthalein disulfonate were not altered by the anesthetics. These data indicate that the hepatobiliary elimination of the glucuronidated metabolites is reduced in rats exposed to volatile anesthetics.

Carbon tetrachloride and the sorbitol pathway in the diabetic mouse

1. Sorbitol dehydrogenase activity and the hepatic and serum concentrations of sorbitol, glucose and fructose were quantified in diabetic mice. 2. Blood glucose concentrations were increased over 300% by diabetes and were decreased toward normal after insulin-treatment. 3. Hepatic sorbitol concentrations ranged from 7-15 mumol/g and were highest in uncontrolled diabetic mice. 4. Hepatic concentrations of fructose and sorbitol were not affected by insulin administration. 5. Challenge with carbon tetrachloride (25 microliters/kg i.p.) did not alter concentrations of glucose, sorbitol or fructose in blood or liver. 6. Sorbitol dehydrogenase activity in blood was increased similarly in normal, diabetic and insulin-treated diabetic mice after CCl4 administration. 7. The data indicate that sorbitol did not accumulate in diabetic mice, and that induction of diabetes did not increase the susceptibility of mice to CCl4 hepatotoxicity as occurs in rats.

Comparison of glucose, sorbitol and fructose accumulation in lens and liver of diabetic and insulin-treated rats and mice

1. The accumulation of glucose, fructose and sorbitol was determined in the lens, liver, and blood from normal, streptozotocin-induced diabetic, and insulin-treated diabetic rats and mice. 2. Sorbitol concentration in rat lens was 10-100 times greater than that in mouse lens, with the highest concentrations in the diabetic animals. 3. Sorbitol levels in rat and mouse liver, and mouse lens were similar and increased only slightly under hyperglycemic conditions. 4. Fructose accumulation was similar in rat and mouse liver and was elevated in the diabetic mouse blood and diabetic rat lens. 5. Aldose reductase activity in rat lens was approximately 350 times that of mouse lens. 6. Lenticular sorbitol dehydrogenase activity in rats was approximately ten times that in mouse lens. 7. Administration of insulin tended to lower liver glucose and subsequent sorbitol formation in the diabetic rat and mouse.

Bile salt binding properties of commonly used gastrointestinal drugs: maalox, carafate, and questran

We have validated a method to measure bile salt binding by Maalox (aluminum hydroxide and magnesium hydroxide), Carafate (sucralfate), and Questran (cholestyramine) in vitro. The method used in this study involves a correction for adherent water volume and thus provides a correct measure of bile salt binding. With this approach, we described the binding properties of Maalox, Carafate, and Questran. The bile salt binding capacities of Carafate and Maalox are limited and do not have physiological or pharmacological significance. On the other hand, we found that Questran has substantial bile salt binding capacity. At the recommended dosage, Questran could deplete the total bile salt pool. We also found that Carafate, although not used as an antacid, has buffering capacity (maintaining a pH of solution in the range 4.2-4.8) which might contribute to its effectiveness as an ulcer treatment drug.

Sibling psychological status and style as related to the disease of their chronically ill brothers and sisters: implications for models of biopsychosocial interaction

This study explores the relationship between disease type and disease activity, and the psychological status of siblings of chronically ill children. Closest-age siblings of children with Crohn's disease (CD) (n = 41) and ulcerative colitis (UC) (n = 24) were assessed for psychological disorder and psychological style, using reliable and standardized measures. The disease activity of the patients was also evaluated. Assessment occurred during outpatient visits to a pediatric gastroenterology division. Results indicated that CD siblings had more psychological disorder than UC siblings. This was not due to greater acute disease activity in the CD patients. However, as a group, siblings of the sickest CD patients displayed more "internalizing" behaviors, whereas siblings of the healthiest CD patients displayed more "externalizing" behaviors. UC siblings, who were psychologically healthier, displayed "externalizing" behaviors regardless of the patient's disease activity. These results are in accord with our previous findings on family functioning, which, together, yield a heuristic model representing the different patterns of biopsychosocial interaction for CD in contrast to UC.

The effect of long-term streptozotocin-induced diabetes on the hepatotoxicity of bromobenzene and carbon tetrachloride and hepatic biotransformation in rats

To exclude the possibility that changes in hepatotoxicity and biotransformation were induced by diabetogen administration, the influence of long-lasting experimental insulin-dependent diabetes on the activities of benzphetamine demethylase, styrene oxide hydrolase, and UDP-glucuronosyl-transferases toward 1-naphthol, diethylstilbestrol, estrone and testosterone, and glutathione S-transferases toward 1-chloro-2,4-dinitrobenzene, ethacrynic acid, and sulfobromophthalein was studied. Adult male Sprague-Dawley rats injected with 45 mg streptozotocin/kg rapidly developed the classical symptoms of diabetes which persisted throughout the 90-day test period. Ketonemia was detectable at 6 but not at either 35 or 90 days after streptozotocin administration. After acute challenge with bromobenzene or carbon tetrachloride (CCl4), aspartate and alanine aminotransferase activities in rats diabetic for 35 and 90 days were markedly higher than those in normal rats, suggesting that diabetes potentiated the hepatotoxicity of these chemicals. Administration of 25 microliters CCl4/kg, ip, to diabetic rats decreased enzyme activities toward benzphetamine, sulfobromophthalein, 1-chloro-2,4-dinitrobenzene, and 1-naphthol. In normal rats, a dose of 400 microliters CCl4/kg, ip, was required to cause similar changes in enzyme activities. Bromobenzene (500 microliters/kg, ip) elicited opposing responses in diabetic and normal rats in N-demethylase activity, in UDP-glucuronosyltransferase activity toward 1-naphthol, estrone, and testosterone, and in glutathione S-transferase activity toward 1-chloro-2,4-dinitrobenzene. Total cytochrome P450 concentrations were reduced by both induction of diabetes and hepatotoxicant challenge. Thus, chronic uncontrolled diabetes alters the response of hepatic xenobiotic biotransformation enzymes in a non-uniform, substrate-dependent manner, independent of initial diabetogen effects. The role of cytochrome P450j in potentiating CCl4 toxicity is discussed.

Hepatic phase II biotransformation in C57Bl/KsJ db/db mice: comparison to that in Swiss Webster and 129 REJ mice

1. Cytochrome P-450 concentrations were similar in male and female carrier (db/+) and diabetic (db/db) mice. Benzphetamine N-demethylase and styrene oxide hydrolase activities were 47 and 65% lower in db/+ than in db/db mice. 2. UDP-Glucuronosyltransferase activity toward 1-naphthol, estrone and diethylstilbestrol was not different between db/db and db/+, but was 40% higher in db/db mice toward testosterone. 3. Glutathione S-transferase activity toward 1-chloro-2,4-dinitrobenzene and ethacrynic acid was 47 and 59% lower in db/db mice than in male db/+ mice. Female db/+ mice had similar activities to those found in diabetic animals. 4. The differences in enzyme activity between hyperinsulinemic and normal animals suggest that insulin can influence both phase I and phase II biotransformations. 5. Enzyme activities in db/+ and db/db mice were compared to those in 129 REJ and Swiss Webster mice.

Successful management of an acquired gastric outlet obstruction with endoscopy guided balloon dilatation

Antral-pyloric strictures and gastric outlet obstruction are known complications of caustic ingestions. These lesions can develop even in the absence of overt signs of potentially serious upper gastrointestinal tract pathology such as oropharyngeal burns, dysphagia, vomiting, or abdominal pain at the time of ingestion. The development of radial balloon catheters, which can be endoscopically guided into narrow strictures and inflated, offers an alternative therapy to surgical resection of obstructing lesions. We report the successful management of a pyloric stricture secondary to a caustic ingestion by sequential endoscopically guided balloon dilatations and offer guidelines for the use of this procedure.

Pneumatic dilatation and operative treatment of achalasia in children

The therapeutic approach to children with achalasia of the esophagus is controversial. Both pneumatic dilatation (PD) and Heller esophageal myotomy (EM) are considered effective, while bougienage has been discarded by most authorities. To determine the best place for each in the therapy of achalasia, 19 cases treated since 1964 were reviewed. Ages ranged from 9 months to 17 years (median 11 years), and duration of symptoms ranged from 4 months to 8 years (median 1 year). Three patients had symptoms from infancy. Two patients underwent a successful EM as their sole procedure. Two underwent bougienage as their initial therapy. Dysphagia recurred quickly and both required operation. Fifteen underwent PD under intravenous sedation with a Brown-McHardy dilator placed under fluoroscopy. Seven underwent a single dilatation; seven underwent two; and one underwent four. Relief of dysphagia was achieved in 11 patients, but four required surgery. The patients who experienced adequate relief with dilatation alone were clinically identical to those in whom it failed with respect to age, race, sex, symptom duration, and manometric data. Those who required EM following PD experienced only a brief period of relief following PD (median 1 month) compared with those who enjoyed lasting results (median 18 months). Three patients suffered prolonged chest pain or fever following PD, but without esophageal leakage and with full recovery. Two of eight operative patients developed late postoperative reflux. There were no deaths. Both PD and EM are safe and effective treatments for achalasia. Our results indicate that dilatation is the logical first therapeutic step, but rapid recurrence of symptoms may identify those patients who will require operative myotomy.

Characterization of xenobiotic biotransformation in hepatic, renal and gut tissues of cattle and sheep

Microsomal and cytosolic preparations of hepatic, renal, ileal and ruminal tissues of cattle and sheep were used to measure oxidative, hydrolative and conjugative biotransformations of 11 xenobiotic substrates. Within species, enzyme activities were generally higher (P less than .05) in hepatic than non-hepatic tissue but, in both species, non-hepatic tissue exhibited considerable capacities for metabolizing certain substrates. Sheep rumen wall (with papillae) was notably high in cytochrome P-450 content (34% of hepatic value), in glutathione conjugation of ethacrynic acid (223% of hepatic activity; P less than .05), and UDP-glucuronidation of estrone (290% of hepatic activity; P less than .05). Sheep differed (P less than .05) from cattle, having lower cytochrome P-450 content in liver and ileum (but not kidney); lower N-demethylase activity in liver, but two- to threefold higher activity in kidney; lower sulfotransferase activity in liver and kidney; and higher glutathione S-transferase activity toward certain substrates. UDP-glucuronidation varied too widely among substrates to afford strong generalization in comparisons among tissues or between species. Non-hepatic tissues in ruminants exhibit considerable capacities for oxidative, hydrolative and conjugative metabolism of xenobiotics. Sheep and cattle differ widely in hepatic and non-hepatic capacities for biotransforming certain xenobiotics.

Alterations in biliary excretory function by streptozotocin-induced diabetes

Hepatic clearance and biliary excretion of model substrates for each of four carrier-mediated transport systems were studied in male Sprague-Dawley rats treated 28 days earlier with 45 mg/kg streptozotocin iv to induce uncontrolled insulin-deficient diabetes. Diabetic rats exhibited hyperglycemia (560 mg/dl), polyuria (160 ml/24 hr), polyphagia, polydipsia, and generalized myopathy. The plasma disappearance, biliary excretion, and elimination half-life of the anionic dye phenol red was unchanged in diabetic rats, but total clearance of phenol red was increased. Conjugation of phenol red with glucuronic acid appeared to be increased in diabetic rats, whereas acetylation of procainamide ethobromide was decreased. Plasma elimination and total clearance of cationic procainamide ethobromide, uncharged ouabain, and the bile acid taurocholate were significantly increased in diabetic animals. Biliary excretion of these three compounds was only slightly elevated in the first 15 min after administration and was decreased after 1 hr. Biliary and total systemic clearance were also increased from 2-3-fold for procainamide ethobromide, ouabain, and taurocholate. These changes in clearance are predominantly due to the 2-5-fold increase in steady state volume of distribution. Basal bile flow rates were increased by 62% after the induction of diabetes to 88 microliter/min/kg. Diabetic rats secreted higher levels of bile acids, cholesterol, and phospholipids into bile. These data indicate that long term insulin-dependent diabetes does alter hepatic excretory function.

Hepatic biotransformation in lean and obese Wistar Kyoto rats: comparison to that in streptozotocin-pretreated Sprague-Dawley rats

1. Phase I and phase II biotransformation was compared in streptozotocin-induced hypoinsulinemic (STZ) and genetic hyperinsulinemic (WKY-fatty) rats. 2. Total cytochrome P-450 concentrations were reduced in both STZ and WKY, whereas styrene oxide hydrolase and benzphetamine N-demethylase activities were normal in STZ and reduced in WKY. 3. UDP-glucuronosyltransferase activity was decreased toward testosterone and 1-naphthol in STZ and WKY, and was increased toward estrone in the obese female WKY. 4. Glutathione S-transferase activity was decreased in STZ toward 1-chloro-2,4-dinitrobenzene, ethacrynic acid and sulfobromophthalein, but was similar to that in normal rats for WKY.

Biliary excretion of organic anions in diabetic rats

Little definitive data are available concerning the effects of insulin deficiency on the hepatic uptake and biliary excretion of endogenous or xenobiotic substances. To expand our understanding of this area, male Sprague-Dawley rats were pretreated with streptozotocin (45 mg/kg i.v.) to induce uncontrolled diabetes. Four to five weeks later, diabetic rats exhibited elevations in serum glucose (640 +/- 13 mg/dl), biliary glucose (307 +/- 35 mg/dl), urine output (166 +/- 11 ml/24 hr), basal bile flow rate (73 +/- 2 microliter/min/kg), liver weight/body weight ratio and bile acid pool size. Polyphagia and generalized muscle atrophy were also evident. Plasma disappearance and biliary excretion of several organic anions were studied after i.v. administration. There were no differences between control and diabetic rats in the plasma elimination and biliary excretion of eosin, phenol-3,6-dibromphthalein disulfonate and sulfobromophthalein. Although hepatic uptake was unchanged, the biliary excretion of amaranth was decreased 30% in diabetic rats. There were no differences in bile flow rate in control or diabetic rats after administration of these four anions. In contrast, administration of indocyanine green, bromcresol green and rose bengal did not depress bile flow in diabetic rats as was observed in control rats. In addition, the rate of maximal biliary excretion was increased by 390, 240 and 151% for rose bengal, indocyanine green and bromcresol green, respectively. Plasma clearance of rose bengal was 65% higher in diabetic rats. Total body clearance and steady-state volume of distribution values for all other anions were not different after induction of diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)

Medium-chain and long-chain acyl CoA dehydrogenase deficiency: clinical, pathologic and ultrastructural differentiation from Reye's syndrome

The clinical and pathologic findings in 12 patients with medium-chain acyl CoA dehydrogenase deficiency and three patients with long-chain acyl CoA dehydrogenase deficiency are summarized. Although these inborn errors of intramitochondrial beta-oxidation of fatty acids present with similar findings to Reye's syndrome, there are clinical, laboratory and hepatic histologic differences. Younger age at presentation, history of unexplained sibling death, a previous episode of lethargy, hypoglycemia or acidosis precipitated by fasting stress and only mildly elevated serum transaminases with normal or only mildly prolonged prothrombin time may all suggest an acyl CoA dehydrogenase deficiency. Long-chain acyl CoA dehydrogenase deficiency is differentiated from medium-chain acyl CoA dehydrogenase deficiency by younger age at presentation, more profound cardiorespiratory depression, evidence of cardiomyopathy, and sequelae of muscle weakness, hypotonia and developmental delay. Definitive diagnosis is made by assay of medium-chain or long-chain enzyme activity in cultured skin fibroblasts or in leukocytes. Hepatic light microscopic alterations are essentially limited to steatosis, which may be either macro- or microvesicular. The cases with microvesicular steatosis can be differentiated morphologically from Reye's syndrome by electron microscopy, showing the absence of the mitochondrial changes characteristic of Reye's. Four of seven cases of acyl CoA dehydrogenase deficiency showed some variations from normal in the appearance of the hepatocyte mitochondria. The relationship of these variations to the basic metabolic defect(s) remains to be determined.

Xenobiotic biotransformation in livestock: comparison to other species commonly used in toxicity testing

Wildlife, domesticated animals and humans are exposed daily to myriad chemicals present in our environment. The risk posed by these chemicals to one species is often determined by extrapolation from data gathered from another species. Several extensive studies have examined the capability of the liver to biotransform xenobiotics in animals commonly used in toxicity testing and in livestock. The present paper is a compilation of these data into a single source to permit comprehensive examination of inter-species variation in rates of hepatic biotransformation. Several substrates were studied for each enzyme system, including cytochrome P-450-dependent monooxygenases, epoxide hydrolases, UDP-glucuronosyltransferases, N-acetyltransferases, glutathione S-transferases and sulfotransferases. The numerous differences in substrate specificity for an individual enzymatic pathway reflect the apparent multiplicity of these enzymes in all 11 species studied. Several hundred- to several thousand-fold differences between species in enzymatic activities for certain substrates under well-defined conditions emphasize the need for caution and the risk of error in extrapolation of xenobiotic metabolism from one species to another. In spite of these uncertainties, knowledge of the rate of biotransformation may help us predict the fate of new chemicals in various species.

Effects of ethinyl estradiol on intestinal membrane structure and function in the rabbit

Structural and functional properties of the small intestinal microvillus membrane were evaluated in the rabbit after administration of ethinyl estradiol, a synthetic estrogen with a demonstrated propensity to alter hepatic membrane lipid fluidity, and promote cholestasis. In the jejunum, no estrogen-induced changes in microvillus membrane total lipid, cholesterol or phospholipid content were observed. However, the ileal microvillus membrane in estradiol-treated animals demonstrates significant reductions vs. controls (per mg protein) in total lipid (0.55 milligrams vs. 0.89 milligrams) [corrected] and phospholipid (206.7 micrograms vs. 304.91 micrograms) (p less than 0.001) content, as well as modifications in specific phospholipid species. The increase in the ileal microvillus membrane cholesterol: phospholipid molar ratio (0.65 vs. 0.51, p less than 0.05) was associated with a significant decrease in membrane lipid fluidity reflected by an increase in fluorescence anisotropy measurements utilizing diphenyl hexatriene as the fluorophore (r at 25 degrees C = 0.306 vs. 0.282, p less than 0.05). Thermotropic lipid phase transitions, assessed by Arrhenius plots of both fluorescence data and ileal microvillus membrane p-nitrophenylphosphatase activity demonstrate that phase changes occur between and 24 and 28 degrees C in both treated and untreated groups. Within the temperature range studied (40-10 degrees C) no differences from control were observed in microvillus membrane alkaline phosphatase activity following estrogen treatment. These data therefore indicate that ethinyl estradiol-induced effects on microvillus membrane lipid composition and physical properties occur predominantly in the ileum and appear to be related, in part, to specific alterations in the availability of phospholipid following estrogen treatment.

Sphingomyelin lipidosis variant with cirrhosis in the pediatric age group

Two children with a variant of sphingomyelin lipidosis had otherwise unexplained cirrhosis that was histologically inactive and appeared to run an indolent course. The primary clinical problems involved the central nervous system, with vertical supranuclear ophthalmoplegia being the most distinctive feature. Biochemical analysis of cultured skin fibroblasts obtained from one of the children revealed that sphingomyelinase activity was 42% of control values. The typical inconspicuous hepatic storage and cirrhosis, coupled with the important morphologic finding of sea-blue histiocytes in the marrow, suggested that in cases of unexplained infantile or childhood cirrhosis the marrow should be closely examined for such histiocytes. Likewise, in cases of sea-blue histiocytes without evident etiology, with or without cirrhosis, this disease should be considered.

Effect of gestational age upon prealbumin and retinol binding protein in preterm and term infants

The relationships between maternal and umbilical cord levels of prealbumin and retinol binding protein (RBP) were studied in 68 mothers and in their appropriate-for-gestational-age neonates delivered between 25 and 42 weeks gestation. Arterial and venous concentrations of prealbumin and RBP in cord sera were also studied in a subsample of eight infants. In cord sera, prealbumin and RBP levels increased with gestational age (prealbumin, r = 0.47; RBP, r = 0.40, p less than 0.01), and were significantly different in neonates born at term compared to those born prematurely (mean +/- SD, prealbumin 12.0 +/- 3.9 mg/dl vs. 8.8 +/- 2.3 mg/dl, p less than 0.001; RBP, 2.3 +/- 0.8 vs. 1.8 +/- 0.5 mg/dl, p less than 0.005). No significant differences between arterial and venous concentrations of prealbumin and RBP were observed in cord blood. In maternal blood, serum prealbumin and RBP concentrations did not increase with length of gestation (25-42 weeks). Maternal prealbumin was not correlated significantly with infants' cord serum levels; the correlation coefficient for RBP was 0.29, p less than 0.05. Maternal prealbumin and RBP serum levels were approximately twice the values seen in neonates born both at term and prematurely. Although the difference between premature and full-term cord levels of prealbumin and RBP may reflect an increase in hepatic protein synthesis that occurs with maturation of the fetus and/or a change in placental function after 37 weeks gestation, neither of these factors sufficiently explains the variance in neonatal prealbumin and RBP levels.

Progression of neurovisceral storage disease with supranuclear ophthalmoplegia following orthotopic liver transplantation

A 7-year-old girl with progressive ataxia, spasticity, supranuclear ophthalmoplegia, and sea-blue histiocytes in her bone marrow underwent orthotopic liver transplantation for hepatocellular carcinoma. After an initial period of stabilization, she has shown progression of neurologic symptoms with recurrence of storage material in the transplanted liver.

Toxicological effects of gamma-irradiated sewage solids fed as seven percent of diet to sheep for four years

Breeding ewes in drylot were fed pelleted complete diets with 3% cottonseed meal (CSM) or 7% dried, gamma-irradiated sewage solids (DGSS) for 4 yr. Cytochrome P-450 (P-450) content and enzyme activities for xenobiotics biotransformations were assayed in livers after 2 yr and in livers, kidneys and ileal tissue after 4 yr. Dietary DGSS caused no increase in P-450 and few changes in activities of oxidative, hydrolative and conjugative biotransformational enzymes. Consumption of DGSS for 4 yr caused slight enlargement of spleens (1.1-fold, P less than .10) and ovaries (1.3-fold, P less than .10), but no change in size of livers, kidneys, hearts, adrenals and thyroids (P greater than .10), nor liver vitamin A levels (P greater than .10). Of 22 refractory lipophilic residues assayed in abdominal adipose tissue, few were detected and of those detected DGSS caused none to exceed normal levels. Dietary DGSS increased (P less than .01) Fe in livers 1.5-fold and in spleens 5.6-fold, and increased Cu in livers 1.3-fold (P less than .01) and in kidneys 1.2-fold (P less than .05). Dietary DGSS increased Cd levels in livers (P less than .01) but not in kidneys or spleens (P greater than .10); yet all Cd levels were within ranges for livestock fed conventional feed. Dietary DGSS caused no increase (P greater than .10) in levels of Ag, Ca, Cr, Hg, K, Mg, Mn, Na, Ni, P, Pb or Zn in livers, kidneys or spleens. There were no histopathological lesions of toxicosis except mild hemosiderosis of spleens. Consumption of a diet with 7% DGSS throughout 4 yr caused no hazardous accumulation of toxic elements and little, if any, evidence of toxicosis.

Development of UDP-glucuronosyltransferase activity toward digitoxigenin-monodigitoxoside in neonatal rats

Glucuronidation is low or undetectable in embryonic and early fetal tissues and changes to adult levels at rates depending on the acceptor, tissue, and species. Because other data indicate there may be a specific UDP-glucuronosyltransferase (GT) in the liver of adult rats that glucuronidates digitoxigenin-monodigitoxoside (DIG), the development of GT activity in neonatal rats toward DIG was compared with that of other acceptors. Conjugation of p-nitrophenol and 1-naphthol was higher at birth and decreased to adult levels by 20 days of age. Glucuronidation of chloramphenicol, morphine, valproic acid, and bilirubin increased from birth to adult activity by 20 days of age. Conjugation of phenolphthalein, estrone, and diethylstilbestrol was low in 1-day-old rats and higher than adult in 20-day-old animals. In contrast, glucuronidation of DIG was barely detectable (9% of adult) in 20-day-old rats. The concentration of UDP-glucuronic acid was 50% of adult levels at birth and increased to adult values by 10 days of age. Administration of 3-methylcholanthrene on days 6 to 9 after birth significantly stimulated GT activity toward 1-naphthol, p-nitrophenol, and morphine, whereas phenobarbital precociously increased conjugation of chloramphenicol, valproic acid, morphine, and diethylstilbestrol. Pregnenolone-16 alpha-carbonitrile enhanced the development of GT activity toward morphine, chloramphenicol, valproic acid, bilirubin, diethylstilbestrol, and estrone. Glucuronidation of DIG was not increased after 3-methylcholanthrene or phenobarbital, but could be induced after pregnenolone-16 alpha-carbonitrile to 7% of adult values in 10-day-old rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Intestinal membrane lipid composition and fluidity during development in the rat

We have characterized microvillus membrane (MVM) lipid composition and derived estimates of membrane fluidity using fluorescence polarization [with 1,6-diphenyl-1,3,5-hexatriene (DPH) as the probe] in MVM from the jejunum and ileum of suckling (day 14-20) and mature postweaning (day 28-49) rats. The anisotropic values are lower (i.e., increased fluidity) in MVM from jejunum and ileum of suckling rats compared with values from MVM of mature rats, suggesting a more disordered molecular environment in MVMs of suckling animals, although the ileal MVM was relatively less fluid than jejunal membranes in both groups. Anisotropic determinations in protein-free MVM liposomes demonstrate that protein-lipid interactions are major determinants of fluidity estimates. Arrhenius plots of DPH anisotropies in MVM and MVM liposomes indicate a thermotropic lipid-phase transition at 23 degrees C in mature rat jejunum and ileum; however, no clear transition point was observed in 14- to 20-day animals. In addition, both the jejunal and ileal MVM in suckling animals contained greater amounts of total lipid, cholesterol, and phospholipid per milligram protein than did mature MVM preparations. Membrane phospholipid composition changed with age, with a decrease in sphingomyelin and an increase in phosphatidylcholine in the jejunum of the postweaning animal and with similar weight ratios of saturated to unsaturated fatty acids in both age groups. The data demonstrate that the small intestinal MVM manifests both age-dependent and regional proximal-distal differences in lipid composition and biophysical properties.(ABSTRACT TRUNCATED AT 250 WORDS)