Increased Serum Alkaline Phosphatase Activity Research Articles

An overview of the preclinical toxicity and potential carcinogenicity of sitaxentan (Thelin®), a potent endothelin receptor antagonist developed for pulmonary arterial hypertension

Sitaxentan (Thelin®), an endothelin receptor antagonist with a long duration of action and high specificity for the endothelin receptor A subtype, was used to treat pulmonary arterial hypertension. It was withdrawn from the market due to an idiosyncratic risk of drug-induced liver injury identified from emerging clinical trial data and clinical case reports. The preclinical safety profile of sitaxentan is presented, including single- and repeat-dose toxicity in mice, rats, and dogs and carcinogenicity in mice and rats. Sitaxentan-related adverse effects included coagulopathy in rats and dogs, increased serum alkaline phosphatase activity in mice and dogs, and hepatic hypertrophy in all species. Decreased albumin, erythrocyte count, hemoglobin concentration and hematocrit, and increased coagulation times and liver weight were also noted. These effects generally occurred at systemic exposures (AUC0–24) that were substantially greater than those seen in humans. Twice-daily (vs. once daily) dosing resulted in increased toxicity, which correlated with increased trough plasma sitaxentan concentrations. Sitaxentan appeared to have a low potential for testicular and hepatic toxicity and was not carcinogenic. These studies suggested that sitaxentan would have a reasonable margin of safety when used as directed in humans and supported a positive benefit:risk assessment at the time of marketing approval.

Histomorphometric alteration of knee articular cartilage and serum alkaline phosphatase in young female mice by chronic supplementation with soybean

The purpose of the present study was to examine the effect of soybean supplementation on cartilage thickness in the knee joint and serum levels of alkaline phosphatase (ALP) in mice. Forty female mice were fed for 6 months on one of four regimens: low protein, complete protein without soybean, and complete protein containing either 20% or 40% soybean. Body weight differences, histological and histomorphometric analysis, and ALP levels were determined and compared after 6 months. The results showed a significant increase in serum ALP activity and cartilage thickness in both groups fed on soybean-containing diets, compared with the other groups. Additionally, the number of chondrocytes was significantly increased (p < 0.001) in the group taking the 40% soybean regimen, and the proteoglycan content of the intracellular fluid in the tibia was higher in those groups taking soybean. In conclusion, the present study suggests that soybean supplementation is capable of stimulating ALP production and reducing cartilage loss in young female mice. Soybean supplementation during childhood may therefore be potentially useful in protecting joints.

A Case of Renal Osteodystrophy with Unexpected Serum Intact Parathyroid Hormone Concentrations

A 64-year-old female with long-standing end-stage renal disease (ESRD),1 status post 2 failed renal transplants, was evaluated for management of renal osteodystrophy with particular concern for adynamic bone disease (ABD). ABD was suspected because of low normal serum intact parathyroid hormone (PTH) concentrations (range 2.5–54 ng/L, reference range 10–65 ng/L), intermittently increased serum calcium concentrations (range 88–107 mg/L, reference range 84–105 mg/L), and severe osteoporosis. However, her mildly increased serum alkaline phosphatase activities (range 149–196 U/L, reference range 30–120 U/L) were inconsistent with the low bone turnover observed in ABD. This discrepant clinical profile prompted investigation into the PTH assay used at our institution. Simultaneous samples were analyzed for intact PTH on our Roche Elecsys 2010 immunoassay analyzer and at a reference laboratory (Quest Diagnostics) on the Siemens Immulite 2000 immunoassay analyzer. Discrepant values of 48 and 786 ng/L were obtained, respectively. Parathyroid hormone functions to maintain serum calcium concentrations within a tight physiologic range. Patients with chronic renal failure develop secondary hyperparathyroidism owing to decreased renal production of 1,25-dihydroxyvitamin D and hyperphosphatemia, both of which result in hypocalcemia. These derangements in mineral metabolism stimulate PTH production to raise serum calcium and promote phosphorus excretion. Increased serum PTH leads to excessive bone resorption through stimulation of osteoblasts and osteoclasts. The combination of secondary hyperparathyroidism and mineralization defects (osteomalacia) represents the most common form of renal osteodystrophy (ROD). In contrast, a subtype of ROD known as adynamic bone disease can be observed in the setting of prolonged peritoneal or hemodialysis, oversuppression of PTH with calcitriol or calcium-based phosphate binders, or the use of bisphosphonates for osteoporosis treatment (1). ABD is characterized by marked suppression of bone remodeling that leads to fracture. Common biochemical hallmarks of ABD include hypercalcemia, low or inappropriately normal PTH concentrations, and reduced markers of bone turnover …

Description of dogs naturally infected with Hepatozoon canis in the Aegean region of Turkey

Clinical and laboratory findings recorded in 10 dogs naturally infected with Hepatozoon canis in the Aegean region of Turkey were reported. The diagnosis was made by finding H. canis gamonts within leucocytes in Giemsa-stained blood smears. H. canis parasitaemia level was calculated manually by counting 500 neutrophils in blood smears. Parasitaemia varied from 1% to 23% of the circulating neutrophils. Anorexia, fever, depression, weight loss, and lymphadenopathy are the main clinical signs in infected dogs. All dogs had microcytic normochromic anaemia; however, 7 of the dogs had neutrophilia, 1 had lymphopenia, 2 had monocytosis, 1 had eosinophilia, and 9 had thrombocytopenia. Abnormal serum biochemical values were hyperproteinaemia (7 of 10 dogs), hypoalbuminaemia (9 of 10 dogs), hyperglobulinaemia (7 of 10 dogs), increased serum alkaline phosphatase activity (2 of 10 dogs), and increased serum creatinine kinase activity (8 of 10 dogs). Concurrent infections such as Ehrlichia canis, Anaplasma phagocytophilum, and Anaplasma platys were detected with a polymerase chain reaction test and 8 dogs had 2 or 3 of these concurrent infections.

EFFECT OF SEA-BUCKTHORN ALCOHOLIC EXTRACTS (HIPPOPHE FRUCTUS ) ON HEPATIC AND RENAL FUNCTIONS IN LABORATORY RAT

In order to observe the blood biochemical modifications as an indicator of hepatic and renal dysfunctions that results after treatment with supplementary copper doses in feed, 48 weaned, male Wistar rats were studied, during a period of three weeks. Primary objective of the research was to observe the blood biochemical modifications in case of copper associated pathology on the base of the activity of some enzymatic systems, modified as a consequence of overdosing copper products in rats, and the influence of alcoholic extracts from sea-buckthorn fruits (Hppophae Fructus) on these parameters, knowing its important antioxidant activity, due to the high content of ascorbic acid, tocopherols, polyphenols, carotenoids and selenium. In rats, hepatic and kidney toxicity was evidently indifferent of the copper dose added in feed, and it was expressed by the increased activity of serum transaminases and alkaline phosphatase, associated with an increased level of blood nitrogen urea and creatinine levels. The studied enzymes activities indicated changes in the hepatic and renal functions, confirming the toxic action of copper, registering lower levels of investigated enzymes activity in the case of alcoholic extracts from sea-buckthorn fruits (Hppophae Fructus) supplementary administered into feed that show a significant antioxidant action, which reduce the risks.

The effect of 3-hydroxybutyrate on the in vitro differentiation of murine osteoblast MC3T3-E1 and in vivo bone formation in ovariectomized rats

3-hydroxybutyrate (3HB), one of the degradation products of microbial biopolyesters polyhydroxyalkanoates (PHA), is a high energy metabolic substrate in animals. This study evaluated the effects of 3HB on growth of osteoblasts in vitro and on anti-osteoporosis in vivo. Alkaline phosphatase (ALP) assay, Van Kossa assay and Alizarin S red staining were used to study in vitro differentiation of murine osteoblast MC3T3-E1 cells. The intensity of in vitro cell differentiation measured in ALP was in direct proportion to the concentration of 3HB when it was lower than 0.01 g/L. Calcium deposition, a strong indication of cell differentiation, also showed an obvious increase with increasing 3HB concentration from 0–0.1 g/L, evidenced by Alizarin red S staining and Van Kossa assay. RT-PCR also showed significantly higher expression of osteocalcin (OCN) mRNA in MC3T3-E1 cells after 3HB administration. In vivo study using female Wistar rats (3 months old, n=80) allocated into normal, sham-operated or ovariectomized (OVX) group that led to decreasing bone mineral density (BMD), bone histomorphometry and biomechanics compared with normal and sham groups, had demonstrated that 3HB increased serum ALP activity and calcium deposition, decreased serum OCN, prevented BMD reduction resulting from OVX. All these led to enhanced femur maximal load and bone deformation resistance, as well as improved trabecular bone volume (TBV%). In conclusion, 3HB monomer containing PHA can be effective bone growth stimulating implant materials.

Cutaneous metastasis of primary appendicular osteosarcoma in a dog

A 6-year-old, neutered male Rottweiler was presented to the University of Illinois Veterinary Teaching Hospital because of a lytic bone lesion involving the distal portion of the right radius and possible pulmonary metastases on thoracic radiographs. Results of serum biochemical analysis were unremarkable. Aspiration and cytologic examination of the bone lesion indicated likely sarcoma with reactive bone. Cutaneous masses were found on the left thigh, interscapular region, and dorsal lumbar region, 4 weeks after initial presentation. Neoplastic spindle cells were found in aspirates from 2 of the masses. The neoplastic cells stained positive for alkaline phosphatase activity using cytochemistry. Re-evaluation of serum biochemical values at this time revealed a marked increase in alkaline phosphatase activity (413 U/L, reference interval 12-110 U/L) compared with the initial value (26 U/L). Due to progressive disease, the dog was euthanized and a necropsy was performed. Histologic findings included primary osteosarcoma of the distal portion of the right radius, with metastases in the lungs, spleen, left fourth and fifth ribs, soft tissue of the right medial thigh, and T1-T3/interscapular region. Cutaneous metastasis of primary appendicular osteosarcoma has been reported rarely in animals and humans. Increased serum alkaline phosphatase activity may be a potential indicator of poor prognosis for this neoplasm.

Effects of Dietary Genistein on Nutrient Use and Mineral Status in Heat-Stressed Quails

Genistein is a powerful antioxidant and plays a role in calcium and bone metabolism. We evaluated the efficacy of dietary supplementation with genistein on the nutrient use and mineral concentrations in tibia and serum of quails reared at high environmental temperature (34 degrees C). Two hundred and forty Japanese quails (10 days old) were randomly assigned to 8 treatment groups consisting of 10 replicates of 3 birds. The birds were kept in a temperature-controlled room at 22 degrees C (Thermoneutral, TN groups) or 34 degrees C (for 8 h/d; 09.00 am-05.00 pm; Heat stress, HS groups). Birds were fed either a basal diet (TN and HS) or the basal diet supplemented with 200, 400 or 800 mg of genistein/kg of diet. Heat exposure decreased apparent nutrient digestibility and bone mineralization when the basal diet was fed (P < 0.001). Apparent digestibility of dry matter (DM) (P < 0.05), crude protein (CP) (P < 0.05) and ash (P < 0.01) was significantly improved by genistein supplementation. However, this improvement was not in direct proportion to increased doses of supplement since there was no difference when diets included either 400 or 800 mg genistein/kg of diet (P < 0.05) in birds reared under heat stress. The amounts of Ca, P, Mg, Mn, Zn, Fe and Cu in the excreta decreased (P < 0.01), while Ca, P, Mg, Mn, Zn and Cu concentrations in tibia ash increased in quails reared under heat stress conditions (P < 0.01) with genistein supplementation. Ca and P concentrations in tibia ash were also increased in birds kept under thermoneutral conditions with genistein supplementation. Increased serum alkaline phosphatase activity (P < 0.01) was associated with increasing dietary genistein in all groups. In conclusion, genistein supplementation to the basal diet improved digestibility of CP, DM and ash and levels of Ca and P and bone mineralization in quails reared under heat stress conditions.

Increased Serum Alkaline Phosphatase Activity Originating from Neutrophilic Leukocytes

To the Editor: In healthy adults, most of the alkaline phosphatase (ALP) activity in serum (1) derives from liver ALP and bone ALP (2). Neutrophil ALP (NAP) is detectable in differentiated neutrophils and monocytes (3) and is the product of the liver/bone/kidney-type ALP gene (4). NAP mRNA and enzyme activity are induced by treatment of neutrophils with granulocyte colony-stimulating factor (G-CSF) in vitro (5); however, neutrophils are not usually identified as the source of increased serum ALP activity. Here we present data from several patients in whom neutrophils appeared to be a source of increased ALP activity. Serum ALP activity was measured by the method of the Japanese Society of Clinical Chemistry (6). Serum ALP isoenzymes were separated electrophoretically with Titan III supporting media (Helena Laboratories). A 68-year-old man (patient 1) with easy fatigability presented with leukocytosis (55.3 × 109/L) and a high neutrophil count …

The effect of vitamin K2 on bone metabolism in aged female rats

Reactive oxygen species (ROS) may contribute to aging and osteoporosis resulting from marked decreases in plasma antioxidants in aged osteoporotic women. On the other hand, high-dose vitamin K2 (menaquinone-4: menatrenone, MK-4) supplementation has been reported to reduce ovariectomy-induced bone loss in rats and to decrease osteoporotic fracture in postmenopausal women. However, the mechanism by which vitamin K2 prevents osteoporosis is unclear. Recently, vitamin K2 has been suggested to preserve antioxidant activity as a novel function. Therefore, we investigated the effect of vitamin K2 on the osteoporosis of aged rats by evaluating the relationships between serum antioxidant levels and bone metabolism. Aged female rats exhibited significantly lower serum alkaline phosphatase activity and osteocalcin level, together with lower serum levels of antioxidants such as 17beta-estradiol, macrophage migration inhibitory factor (MIF) and glutathione peroxidase (GPx) activity, as compared with young female rats. On the other hand, vitamin K2 supplementation (500 mg/kg, food intake) for 98 days led to a significantly increased serum vitamin K2 level (3,045+/-915 ng/ml in the vitamin K2 supplemented group vs. 4.6+/-3.4 ng/ml in the control diet group; P<0.0001) with increased serum alkaline phosphatase activity and MIF level (P<0.05). Unexpectedly, however, it failed to increase the serum level of antioxidants such as GPx. Nor did it affect bone metabolism markers such as osteocalcin and osteopontin, which were significantly lower than in the young female rats (P<0.05). Finally, the histomorphometric properties of the proximal tibia in the femur were not altered by vitamin K2. These results suggest that high-dose vitamin K2 supplementation neither improves lowered antioxidant levels nor stimulates bone formation in aged rats.

Onkogene Osteomalazie bei einer 49-jährigen Patientin

A 49-year-old woman presented with increased bone and muscle pain of the left thigh and also of the left ribs since 1 1/2 year. 2 osteolytic regions on the left proximal femur were punctured but no tumour-like changes were found. Laboratory tests showed a severe hypophosphataemia (0.33 mmol/l), increased serum alkaline phosphatase activity and moderate elevated parathyroid hormone. Renal loss of phosphate was measured under phosphate substitution. The bone mineral density (DXA) was decreased. With octreotid scintigraphy a somatostatine receptor positive tumour was detected on the right proximal thigh and magnetic resonance scanning confirmed localization of the tumour. Treatment with oral phosphate and calcitriol improved the complaints presently. After total removal of a mesenchymal tumour, normalization of serum phosphate occurred and the patient did not require any medicine and did not have complaints anymore. In a case of uncertain hypophosphataemic osteomalacia in adults it is essential to search for a tumour after exclusion of the rare differential diagnoses to enable a causal treatment of a potentially oncogenic osteomalacia.

Serum Alkaline Phosphatase Activity As A Potential Biomarker For The Intergrity Of The Hepatic Drainage System In Acute Falciparum Malaria Infection

Introduction: The serum activity of the tissue-specific, membrane-bound enzyme alkaline phosphatase (Orthophosphoric monoester phosphohydrolase, alkaline optimum (E.C. 3.1.3.1))was assayed in the sera of 110 adult patients comprising of 50 males and 60 females (age range, 18 – 40 years) presenting with acute falciparum malaria infection and a control group of 48 healthy adults. Methods: Serum samples were collected from a randomly selected group of individuals confirmed to be infected with the falciparum malaria parasite by microscopic examination of Giemsa stained thin blood slides. Results:Serum alkaline phosphatase activity was significantly increased (6.35 ± 0.39 IU) in female patients relative to the normal females (4.33 ± 0.23 IU), p = 0.003. Serum alkaline phosphatase activity was also higher in male patients (5.85 ± 0.36 IU) when compared to the control activity of (4.83 ± 0.35 IU) in males, p = 0.001. Conclusion: The increased serum alkaline phosphatase activity among the patients indicates that the liver stage of falciparum malaria infection is accompanied by a perturbation of the host hepatocytes drainage pathways where alkaline phosphatase is localized on the membrane. This makes alkaline phosphatase a potentially important biomarker for the assessment of the integrity of the hepatic drainage system in acute falciparum malaria infection.

Clinical Hepatozoon canis infection in a dog in Turkey

A five‐year‐old female dog was presented with a four‐week history of inappetence, weight loss, and skin and gait abnormalities. Physical examination revealed weakness, depression, incoordination of the posterior limbs, emaciation, skin and hair coat alterations, peripheral lymphadenopathy, pale mucous membranes and fever. Laboratory analysis of samples revealed abnormalities which included anaemia, neutrophilic leucocytosis, thrombocytopenia, low serum glucose and albumin concentrations, and increased serum alkaline phosphatase activity. The diagnosis was confirmed microscopically, by demonstrating the presence of Hepatozoon canis gametocytes within neutrophils in Giemsa‐stained peripheral blood smears. Treatment consisting of toltrazuril and a trimethoprim‐sulfamethoxazole combination was effective in relieving the clinical signs and clearing the blood of H canis gametocytes. To the authors’knowledge, this is the first detailed clinical description of H canis infection in a dog in Turkey.

Duration of increased serum alkaline phosphatase activity in dogs receiving different glucocorticoid doses

Exposure to exogenous glucocorticoids can variably increase the serum alkaline phosphatase (alp) activity, however, the duration of this effect in dogs has not been determined. In this study, three groups of ten clinically normal adult dogs were administered different types of glucocorticoids at therapeutic doses. Group 1 received prednisone 1mgkgday−1p.o. for 3 weeks; Group 2 received a single dose of methylprednisone acetate 1·1mgkgday−1s.c.; Group 3 received dexamethasone 0·25mgkg day−1p.o. for 1 week. In Group 1 elevations were statistically significant on days 7, 14 and 21 (P<0·01, P<0·001, P<0·001, respectively). After discontinuing therapy serum alp returned to baseline levels in 7 days. In Group 2, serum alp activity remained significantly elevated for 3 weeks after therapy (P<0·05, P<0·001, P<0·01 on days 7, 14 and 21 respectively). In Group 3, serum alp levels were significantly increased after 1 week of therapy (P<0·001) returning to basal levels 2 weeks after discontinuing glucocorticoid administration. In conclusion, duration of increased serum alp activity was variable and with the protocols assessed a 3-week period for short-acting glucocorticoids and more than 4 weeks for long-acting methylprednisone may be required to return to baseline levels in all dogs.

Bone effects of hexarelin, a GH-releasing peptide, in female rats: influence of estrogen milieu.

The present study was performed to evaluate the potential influence of the estrogen milieu in modulating the effects of GH/IGF stimulation by a GH-releasing peptide, hexarelin (HEXA), on bone metabolism and mineral density in middle-aged female rats. HEXA was administered for 60 days (50 microg/kg s.c. twice a day) to intact and ovariectomized (OVX) 11-month-old female rats and changes in bone parameters were evaluated with respect to those of the same rats under baseline conditions and with those of control rats (intact and OVX) administered isovolumetric amounts of physiological saline. Serum total alkaline phosphatase (ALP) and urinary deoxypyridinoline (Dpd) were measured before and at various times during HEXA treatment. Bone mineral content (BMC) and density of lumbar vertebrae and femoral mid-diaphyses were measured by dual energy X-ray absorptiometry before and after treatment. In all groups, serum IGF-I levels were determined before and during treatment and the GH secretory response to HEXA was assessed at the end of the experiment. In intact rats, HEXA did not modify Dpd urinary excretion, induced a trend toward an increase of serum ALP activity and significantly increased BMC (+6.5%) and bone area (+4.1%) only at lumbar vertebrae. In OVX rats, HEXA did not modify the OVX-induced increase in bone turnover markers (Dpd and ALP) and did not affect the OVX-induced vertebral bone loss, but significantly increased BMC (+7.2%) and bone area (+5.3%) at femoral mid-diaphyses. HEXA significantly increased serum IGF-I levels at day 14, but not at day 60, in both intact and OVX rats, whereas the GH secretory response to HEXA was higher in the former than in the latter. Overall, the present data demonstrate that chronic HEXA treatment increases BMC and bone area at lumbar vertebrae in intact rats and at femoral diaphyses in OVX rats. The different sensitivity to HEXA of the skeletal districts examined is related to the estrogen milieu and may reflect a complex interplay between estrogens and GH/IGF function.

Effect of fasting on rat duodenal and jejunal microvilli

Duodenal and jejunal ultrastructural morphology and total serum alkaline phosphatase (ALP) activity were investigated in Wistar rats submitted to normal feeding, a 24 h fasting without or with access to sawdust or expanded polystyrene, and a 22 h fasting followed by a 2 h refeeding. Ultrastructural observation of duodenal and jejunal villous tips showed the occurrence of degenerating epithelial cells that were much more frequent in the epithelium of fasted rats. Refeeding and ingestion of sawdust or expanded polystyrene decreased the mean percentage of degenerating cells in the duodenum but not in the jejunum in comparison to plain fasted animals. Normal feeding produced the highest value of serum ALP activity. Refeeding as well as ingestion of sawdust or expanded polystyrene increased serum ALP activity values from those of plain fasted state: the difference being significant only for the refed group. It is concluded that: a) feeding, for both duodenum and jejunum, and refeeding and mechanical stimulation, just for the duodenum, increased proliferation, decreased apoptosis or facilitated desquamation of the epithelium; b) ALP increase in serum was induced by feeding and refeeding.

Alteration in bilirubin excretion in individuals chronically exposed to arsenic in Mexico

We have studied hepatic function in individuals chronically exposed to arsenic (As) via drinking water in Region Lagunera, Mexico. We studied 51 individuals living in three villages exposed to As in water. Nazareno (0.014 mgAs/l), Santa Ana (0.1 mgAs/l) and Benito Juárez (0.3 mgAs/l). We determined the serum activity of aspartate aminotransferase (SAT) and alanine aminotransferase (ALT) as indicators of hepatocellular injury and that of gamma-glutamyl-transpeptidase (GGT) and alkaline phosphatase (ALP) as indicators of cholestasic injury. Serum bilirubin was used as an indicator of organic conjugated anion transport. Total proteins, albumin and globulin fraction in serum were used as indicators of biosynthetic liver capacity. The main findings of this study were the predominantly conjugated hyperbilirubinemia and increased serum ALP activity which were related to the concentration of total arsenic (TAs) in urine, suggesting the presence of cholestasis in As-exposed individuals. No significant changes were observed in the other parameters studied.

Targeted inactivation of Npt2 in mice leads to severe renal phosphate wasting, hypercalciuria, and skeletal abnormalities.

Npt2 encodes a renal-specific, brush-border membrane Na+-phosphate (Pi) cotransporter that is expressed in the proximal tubule where the bulk of filtered Pi is reabsorbed. Mice deficient in the Npt2 gene were generated by targeted mutagenesis to define the role of Npt2 in the overall maintenance of Pi homeostasis, determine its impact on skeletal development, and clarify its relationship to autosomal disorders of renal Pi reabsorption in humans. Homozygous mutants (Npt2(-/-)) exhibit increased urinary Pi excretion, hypophosphatemia, an appropriate elevation in the serum concentration of 1,25-dihydroxyvitamin D with attendant hypercalcemia, hypercalciuria and decreased serum parathyroid hormone levels, and increased serum alkaline phosphatase activity. These biochemical features are typical of patients with hereditary hypophosphatemic rickets with hypercalciuria (HHRH), a Mendelian disorder of renal Pi reabsorption. However, unlike HHRH patients, Npt2(-/-) mice do not have rickets or osteomalacia. At weaning, Npt2(-/-) mice have poorly developed trabecular bone and retarded secondary ossification, but, with increasing age, there is a dramatic reversal and eventual overcompensation of the skeletal phenotype. Our findings demonstrate that Npt2 is a major regulator of Pi homeostasis and necessary for normal skeletal development.

Subchronic Toxicity Studies of Sucrose Acetate Isobutyrate (SAIB) in the Ratand Dog

Preliminary short-term toxicity studies of sucrose acetate isobutyrate (SAIB) in the dog demonstrated that addition of this additive to the diet was associated with an increase in liver size and elevated serum alkaline phosphatase activity with no evidence of pathological change by light microscopy. To determine the basis for these changes, a 12-week oral toxicity study of SAIB was conducted in the dog and a similar study was performed in the rat. SAIB was fed in the diet to groups of six beagle dogs of each sex at 0, 0.5, 1.0, 2.0 and 4.0%. SAIB was also fed to groups of 40 Sprague--Dawley rats of each sex at levels of 0, 2.5, 5.0 and 10.0%. In the rat study, in addition to routine toxicology parameters, hepatic microsomal enzyme induction was determined using a zoxazolamine hypnotic test, urinary ascorbic acid excretion and determination of hepatic carboxylesterase activity. Sodium phenobarbital was fed to groups of 20 rats of each sex at a dose of 100mg/kg body weight/day by gavage as a positive control for hepatic microsomal enzyme induction. In the dog study, routine toxicological tests were supplemented by tests for bromsulfophthalein (BSP) retention, histochemical staining of liver sections for glycogen, phosphorylase, succinate dehydrogenase, and acid and alkaline phosphatases. Levels of liver lipid, protein, glycogen and carboxylesterase activity were also determined. Electron microscopic examinations were made on liver sections from the dog study at the end of the 12-week SAIB feeding period and after a 2-week withdrawal period. Administration of SAIB to rats did not reveal evidence of any effect on hepatobiliary function, and there was no indication of microsomal enzyme induction. Body weight gain of male rats fed SAIB was decreased, probably as the result of decreased palatability of the diet; SAIB did not affect body weight gain in females. The changes observed in the dogs fed SAIB included increased serum alkaline phosphatase activity with no change in serum alanine aminotransferase, aspartate aminotransferase or lactic dehydrogenase activity and no change in serum electrolyte, serum protein, glucose or bilirubin levels. No haematological changes were observed. BSP retention was observed at all SAIB dose levels. There were no SAIB-related pathological changes in any organ when examined by light microscopy. Examination by electron microscope revealed dilatation of bile canaliculi and an increase in smooth endoplasmic reticulum compared with controls. Histochemical studies also indicated increased enzyme activity of the bile canaliculi. The electron-mocroscope-revealed changes were completely reversed during a 2-week treatment withdrawal period. The dog study did not establish a no-effect level for changes in hepatobiliary function induced by feeding SAIB.

Late protection against chemical induced liver injury with dimethyl sulfoxide: [formula omitted], Dept. of Anesthesiology, University of Arizona, Tucson, AZ

The etiology of chronic bile duct injury and fibrosis in patients with autoimmune cholestatic liver diseases is complex, and likely involves immune cells such as lymphocytes. However, most models of biliary fibrosis are not autoimmune in nature. Biliary fibrosis can be induced experimentally by prolonged exposure of mice to the bile duct toxicant alpha-naphthylisothiocyanate (ANIT). We determined whether lymphocytes contributed to ANIT-mediated biliary hyperplasia and fibrosis in mice. Hepatic accumulation of T-lymphocytes and increased serum levels of anti-nuclear-autoantibodies were evident in wild-type mice exposed to ANIT (0.05% ANIT in chow). This occurred alongside bile duct hyperplasia and biliary fibrosis. To assess the role of lymphocytes in ANIT-induced biliary fibrosis, we utilized RAG1−/− mice, which lack T- and B-lymphocytes. ANIT-induced bile duct injury, indicated by increased serum alkaline phosphatase activity, was reduced in ANIT-exposed RAG1−/− mice compared to ANIT-exposed wild-type mice. Despite this reduction in biliary injury, ANIT-induced bile duct hyperplasia was similar in wild-type and RAG1−/− mice. However, hepatic induction of profibrogenic genes including COL1A1, ITGβ6 and TGFβ2 was markedly attenuated in ANIT-exposed RAG1−/− mice compared to ANIT-exposed wild-type mice. Peribiliary collagen deposition was also reduced in ANIT-exposed RAG1−/− mice. The results indicate that lymphocytes exacerbate bile duct injury and fibrosis in ANIT-exposed mice without impacting bile duct hyperplasia.