Transplantation of adipose-derived mesenchymal stem cells ameliorates acute hepatic injury caused by nonsteroidal anti-inflammatory drug diclofenac sodium in female rats.

BACKGROUND: Although the beneficial role of adipose-derived mesenchymal stem cells (AD-MSCs) in acute liver injury has been addressed by numerous studies employing different liver injury inducers, the role of rat AD-MSCs (rAD-MSCs) in diclofenac sodium (DIC) - induced acute liver injury has not yet been clarified. OBJECTIVE: This study aimed to investigate whether rat adipose- rAD-MSCs injected intraperitoneal could restore the DIC-induced hepatoxicity. METHODS: Hepatotoxicity was induced by DIC in a dose-based manner, after which intraperitoneal injection of rAD-MSCs was performed. RESULTS: Here, the transplanted cells migrated to the injured liver, and this was evidenced by detecting the specific SRY in the liver samples. After administering DIC, a significant decrease in body weight, survival rate, serum proteins, antioxidants, anti-apoptotic gene expression, and certain growth factors, whereas hepatic-specific markers, pro-inflammatory mediators, and oxidative, pro-apoptotic, and ER-stress markers were elevated. These adverse effects were significantly recovered after engraftment with rAD-MSCs. This was evidenced by enhanced survival and body weight, improved globulin and albumin values, increased expression of SOD, GPx, BCL-2, VEGF, and FGF-basic expression, and decreased serum ALT, AST, ALP, and total bilirubin. rAD-MSCs also reduced liver cell damage by suppressing the expression of MDA, IL-1B, IL-6, BAX, JNK, GRP78/BiP, CHOP, XBP-1, and cleaved caspase 3/7. Degenerative hepatic changes and multifocal areas of fatty change within liver cells were observed in DIC-received groups. These changes were improved with the transplantation of rAD-MSCs. CONCLUSIONS: We could conclude that targeted AD-MSCs could be applied to reduce hepatic toxicity caused by NSAIDs (DIC).

Role of Thymosin Beta 4 in the diagnosis of Nonalcoholic Fatty Liver and its relation to Metabolic Syndrome in Egyptian patients.

Nonalcoholic fatty liver disease (NAFLD) is a spectrum of hepatic diseases linked to metabolic and cardiovascular disorders that impair quality of life and increase morbidity and mortality. There has been significant interest in replacing conventional diagnostic tools such as liver biopsy with non-invasive biomarkers for the diagnosis of NAFLD. Thymosin Beta 4 (Tß4) is a G-actin sequestering peptide involved in many critical biological processes. This study aimed to evaluate the role of Tß4 in the diagnosis of NAFLD, and its relation to metabolic syndrome. Eighty patients were enrolled in this study, divided into two equal groups of NAFLD cases (n=40) and a control group (n=40). The two groups were subjected to history taking, physical examination, measurement of waist circumference and body mass index (BMI). Laboratory workup included serum Tß4, insulin resistance (HOMA-IR), fibrosis-4 score (FIB-4), fatty liver index (FLI) and NAFLD fibrosis score (NFL) were calculated for both groups. Serum Tß4 was significantly lower in NAFLD patients (P < 0.001) and there was a significant positive correlation between serum Tß4 and HDL (P = 0.034). On the other hand, there was a significant negative correlation between serum Tß4 and waist circumference (P < 0.001), total cholesterol level (P < 0.001), insulin level (P < 0.001), HOMA-IR (P < 0.001), serum triglycerides (P= 0.025) and FLI (P = 0.004). Serum Tß4 at a cut-off value of ≤900 ng/ml had 100 % sensitivity, 100 % specificity, 100% positive predictive value and 100% negative predictive value for the prediction of NAFLD. In conclusion, serum Tß4 could be used as a biomarker for the diagnosis of NAFLD.

Bronchial decompression following repair of absent pulmonary valve: Fine-tuning by procedural fiberoptic bronchoscopy.

Marked aneurysmal dilation of the central and branch pulmonary arteries in utero in patients with tetralogy of Fallot with absent pulmonary valve can often exhibit extrinsic compression of the trachea and bronchi. The major morbidity in these patients remains postoperative ventilation issues. This case report highlights the role of intraoperative bronchoscopy in providing guidance for obtaining optimal bronchial decompression that was achieved by an initial pulmonary arteriopexy followed by an aortopexy.

Coexistence of diverse heavy metal pollution magnitudes: Health risk assessment of affected cattle and human population in some rural regions, Qena, Egypt.

OBJECTIVE: The purpose of this study was to measure the mean concentrations of heavy metals including aluminum (Al), arsenic, nickel (Ni), mercury, lead (Pb), and cadmium (Cd) and to assess the health hazards due to the exposure of cattle/human population to a distinct or the mixture of heavy metals through various sources. MATERIALS AND METHODS: A total of 180 samples including water sources, animal feed, and raw cows' milk from rural regions in Qena, Egypt, were examined using the inductively coupled plasma emission spectrometer (ICP; iCAP 6200). RESULTS: The data highlighted heavy metal pollution with variable concentrations among most of the investigated regions. All concentrations of Al, Ni, and Cd detected in the feeding stuff showed a strong correlation to their respective levels in milk rather than those detected in water (R 2= 0.072 vs. 0.039, 0.13 vs. 0.10, and 0.46 vs. 0.014, respectively) (p < 0.05). Anisocytosis and poikilocytosis with a tendency to rouleaux formation were evident, and basophilic stippling was a pathognomic indicator for heavy metal toxicity, especially Pb. Leukopenia and macrocytic anemia were shown in 50% and 65% of examined cattle, respectively. The target hazard quotients values were more than one (>1) for all heavy metals from water intake for both children and adults and Al and Cd in milk for children, and the hazard index values were indicated higher for noncarcinogenic health hazards. The target cancer risk values predispose people in the surveyed villages to higher cancerous risks due to exposures to the mixture of heavy metal through the consumption of water and milk. CONCLUSION: The bioaccumulation and transmission of heavy metal mixtures from water sources and feeding material have detrimental influences on milk pollution and cattle health which seem to be a serious issue affecting public health in those rural communities.

Effect of Perivascular Injection of Botulinum Toxin Type A versus Lidocaine in Survival of Random Pattern Flaps in a Rat Model.

BACKGROUND: Botulinum toxin type A has gained popularity in many clinical fields, for a variety of aesthetic and therapeutic purposes. In addition, there have been reports regarding the positive effect of botulinum toxin type A on flap survival by various mechanisms. This study examines the role of botulinum toxin type A and lidocaine in augmentation of flap survival and decreasing the rate of necrosis in random pattern cutaneous flaps. METHODS: In 45 male Sprague-Dawley rats, random pattern skin flaps with different width-to-length ratios were elevated. Botulinum toxin type A, lidocaine, or saline was administered to the base and whole length of the flap. Flap survival was evaluated on day 10 after surgery. The area of flap survival was determined grossly on the basis of its appearance, color, and texture. RESULTS: The botulinum toxin type A group had a greater survival area (p < 0.05) compared with the lidocaine or saline group in flaps with width-to-length ratios of 1:2 and 1:3; however, compared with a width-to-length ratio of 1:1, the flap survival rate shows no statistically significant variations. CONCLUSION: Injection of botulinum toxin type A in random pattern skin flaps improves tissue perfusion and increases the rate of flap survival more than lidocaine in flaps with width-to-length ratios of 1:2 and 1:3.

Surgical management of eumycetoma: experience from Gezira Mycetoma Center, Sudan.

BACKGROUND: In this study, we share our experience of different operative techniques undertaken on 584 eumycetoma patients in the Gezira Mycetoma Center. METHODS: This is a retrospective, descriptive, hospital-based study, conducted to review the surgical treatment of eumycetoma patients. We included all patients diagnosed with eumycetoma who underwent a surgical operation in the center during January 2013-December 2016. RESULTS: A total number of 1654 patients were seen during the study period, and their records were revised, while 584 (35.3%) of them underwent an operation and included in the study. There was a male predominance 446 (76.4%). Surgical excision of mycetoma was the commonest operation performed among 513 (87.8%) patients in comparison with amputation 71 (12.2%). Below-knee amputation and toe amputation are the commonest types of amputation in 36 (6.1%) and 14 (2.3%) patients, respectively. Clinical features determining the type of operation performed included the size of the lesion, whether or not a bone was involved, and the feasibility of primary closure. A wide surgical excision (WSE) is performed mainly when the bone is not involved and when moderate or primary closure is possible or reconstruction is feasible. Amputations will typically follow identifying bone involvement, secondary infection, and an already disabled patient. CONCLUSION: The commonest procedure in our series was WSE and primary skin closure undertaken when the lesion was small (< 5 cm); there was no bone involvement, and the skin closure was achievable. Larger lesions (> 10 cm) without bone involvement were treated with excision and flap/graft. Bone involvement and large primary lesions were more likely to be managed by amputation. Recurrent and relapse of mycetoma were observed in patients with bone involvements or presented with recurrent mycetoma for the second time.

Chloroacetonitrile induces oxidative stress and apoptosis in mouse fetal liver.

Chloroacetonitrile (CAN) is a disinfection by-product of chlorination of drinking water. The present study was designed to investigate the potential adverse effects of maternal exposure to CAN on fetal liver in mice. Based on an initial dose-response experiment, CAN (25mg/(kgday)) was given orally to pregnant mice at gestation day (GD) 6, till GD 18. Fetuses were collected and fetal livers were used for assessing oxidative status, apoptosis and histopathological changes. Maternal exposure to CAN resulted in observed oxidative stress and redox imbalance in fetal liver tissues as marked by significant decrease in reduced glutathione (GSH) and elevation of oxidized glutathione (GSSG), malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in genomic DNA. Further, CAN induced apoptosis as indicated by a significant increase in binding of Hoechst reagent to damaged DNA fragments of fetal liver and enhancement of the activity of caspase-3 in cytosolic fractions of fetal livers. Histopathological examination of fetal livers of CAN-treated mice showed hepatocytes with vacuolated cytoplasm, karyolysis and karyorrhexis as well as depletion of their glycogen content. In conclusion, maternal exposure to CAN adversely affects mouse fetal livers as evidenced by the induction of oxidative stress, apoptosis and histopathological changes.

Haloacetonitriles: metabolism and toxicity.

The haloacetonitriles (HANs) exist in drinking water exclusively as byproducts of disinfection. HANs are found in drinking water more often, and in higher concentrations, when surface water is treated by chloramination. Human exposure occurs through consumption of finished drinking water; oral and dermal contact also occurs, and results from showering, swimming and other activities. HANs are reactive and are toxic to gastrointestinal tissues following oral administration. Such toxicity is characterized by GSH depletion, increased lipid peroxidation, and covalent binding of HAN-associated radioactivity to gut tissues. The presence of GSH in cells is an important protective mechanism against HAN toxicity; depletion of cellular GSH results in increased toxicity. Some studies have demonstrated an apparently synergistic effect between ROS and HAN administration, that may help explain effects observed in GI tissues. ROS are produced in gut tissues, and in vitro evidence indicates that ROS may contribute to the degradation and formation of reactive intermediates from HANs. The rationale for ROS involvement may involve HAN-induced depletion of GSH and the role of GSH in scavenging ROS. In addition to effects on GI tissues, studies show that HAN-derived radiolabel is found covalently bound to proteins and DNA in several organs and tissues. The addition of antioxidants to biologic systems protects against HAN-induced DNA damage. The protection offered by antioxidants supports the role of oxidative stress and the potential for a threshold in han-induced toxicity. However, additional data are needed to substantiate evidence for such a threshold. HANs are readily absorbed from the GI tract and are extensively metabolized. Elimination occurs primarily in urine, as unconjugated one-carbon metabolites. Evidence supports the involvement of mixed function oxidases, the cytochrome P450 enzyme family and GST, in HAN metabolism. Metabolism represents either a detoxification or bioactivation process, depending on the particular HAN and the enzyme involved. HANs can inhibit CYP2E1-mediated metabolism, an effect which may be dependent on a covalent interaction with the enzyme. In addition, HAN compounds inhibit GST-mediated conjugation, but this effect is reversible upon dialysis, indicating that the interaction does not represent covalent binding. No subchronic studies of HAN toxicity are available in the literature. However, studies show that HANs produce developmental toxicity in experimental animals. The nature of developmental toxicity is affected by the type of administration vehicle, which renders interpretation of results more difficult. Skin tumors have been found following dermal application of HANs, but oral studies for carcinogenicity are negative. Pulmonary adenomas were increased following oral administration of HANs, but the A/J strain of mice employed has a characteristically high background rate of such tumors. HANs interact with DNA to produce unscheduled DNA repair, SCE and reverse mutations in Salmonella. HANs did not induce micronuclei or cause alterations in sperm head morphology in mice, but did induce micronuclei in newts. Thus, there is concern for the potential carcinogenicity of HANs. It would be valuable to delineate any relationship between the apparent threshold for micronuclei formation in newts and the potential mechanism of toxicity involving HAN-induced oxidative stress. Dose-response studies in rodents may provide useful information on toxicity mechanisms and dose selection for longer term toxicity studies. Additional studies are warranted before drawing firm conclusions on the hazards of HAN exposure. Moreover, additional studies on HAN-DNA and HAN-protein interaction mechanisms, are needed. Such studies can better characterize the role of metabolism in toxicity of individual HANs, and delineate the role of oxidative stress, both of which enhance the capacity to predict risk. Most needed, now, are new subchronic (and chronic) toxicity studies; the results of such well-planned, controlled, conducted, interpreted and published investigations would be valuable in establishing margins of safety for HANs in human health risk assessment.

Dibromoacetonitrile-induced protein oxidation and inhibition of proteasomal activity in rat glioma cells.

Dibromoacetonitrile (DBAN) is a disinfection byproduct of water chlorination. The present study was designed to investigate the potential oxidative protein modifications and alterations in proteasomal activity induced by DBAN in C6 glioma cells (C6 cells). Cells were exposed to 50-400 ppb DBAN for 24 h or 48 h. Cellular viability and lactate dehydrogenase (LDH) leakage were unaffected at 24 h. However, at 48 h after exposure to high concentrations of DBAN, there was a significant decrease in cell viability accompanied by a significant increase in LDH leakage. Exposure to DBAN for 48 h significantly enhanced formation of reactive oxygen species (ROS) in a concentration-related manner. Incubation of C6 cells for 24h or 48 h caused 1.3-2.4-fold increase in levels of lipid peroxidation as indicated by malondialdehyde (MDA)+4-hydroxy-2(e)-nonenal (4-HNE). Further, DBAN induced a concentration and time-dependent increase (1.6-6-folds) in the levels of protein carbonylation. At 48 h, proteasomal activities were found to decrease to 80%, 72%, 46%, and 34% of control with 50 ppb, 100 ppb, 200 ppb, 400 ppb DBAN, respectively. In conclusion, the present study indicates that exposure of C6 cells to DBAN results in generation of ROS, lipid peroxidation, accumulation of oxidized proteins and inhibition of proteasomal activity.

Clinical evaluation of 1,3-butadiene neurotoxicity in humans.

1,3-Butadiene is one of the most commonly produced chemicals in the United States. It is also a known human and animal carcinogen. Information about 1,3-butadiene induced neurotoxicity is scarce. In this study, we evaluated the outcome of 1,3-butadiene accidental contact on neurological function in humans known to be environmentally exposed to the chemical. Known clinical neurological criterions were applied for the identification and evaluation of 1,3-butadiene neurotoxicity. Statistical analysis was conducted on the collected neurological parameters from a random cohort of 310 patients who had been environmentally exposed to 1,3-butadiene and compared with a cohort of 50 matched individuals with similar backgrounds but who were not exposed to 1,3-butadiene (control). Results indicate that 1,3-butadiene has met the criteria and features of a neurotoxin. Exposure to 1,3-butadiene provokes neurological risks that were reversible in most patients. About 6% (18 patients) of the exposed patients demonstrated irreversible neurotoxicity that may need to be longitudinally scrutinized.

The water disinfectant byproduct dibromoacetonitrile induces apoptosis in rat intestinal epithelial cells: possible role of redox imbalance.

Chemically induced oxidative stress poses cytotoxic effects on intestinal epithelial cells that may trigger various forms of injuries in intestinal mucosa. Haloacetonitriles, including dibromoacetonitrile (DBAN, a drinking water contaminant and direct acting mutagen and carcinogen), are known to induce GI disorders. Earlier, we showed that dichloroacetonitrile (DBAN analog) alters glutathione status and increases reactive oxygen species in murine macrophage cell line. Therefore, the present study was undertaken to understand the role of redox imbalance and apoptosis in DBAN-induced GI disorders using rat intestinal epithelial (RIE) cells. Cultured confluent monolayers of RIE cells were continuously exposed to DBAN at 50 to 400 ppb (0.6 to 4.4 muM). After 24, 48, and 72 h of the exposure, oxidative stress and apoptosis were determined. At higher exposure regimens (100 to 400 ppb), a concentration- and time-dependent increase in glutathione disulfide levels (1.5 to 4-fold and 1.6 to 5-fold, p < 0.05) was noticed at 48 and 72 h, respectively, as compared to control. Severe depletion of reduced glutathione was also observed at 72 h after DBAN treatment. DBAN-induced oxidative stress was demonstrated at all concentrations by increased malondialdehyde (MDA) levels (1.3 to 3- and 1.8 to 4-fold, p < 0.05) at 48 and 72 h after treatment, respectively. Increase (1.3 to 2-fold, p < 0.05) in 8-hydroxy-2-deoxyguanosine (8OHdG) levels was observed at 48 h after treatment with 100-400 ppb DBAN. At 72 h these levels were 1.7 to 3- fold higher in DBAN-treated RIE cells as compared to control. DBAN-induced apoptosis, evaluated using TUNEL assay and differential staining techniques, indicates an increase in nuclear damage along with various apoptotic features using epifluorescence or light microscopy. The results of the present study suggest that DBAN-induced redox imbalance could lead to apoptosis and overall oxidative stress in RIE cells.

Fetal origin of adverse pregnancy outcome: the water disinfectant by-product chloroacetonitrile induces oxidative stress and apoptosis in mouse fetal brain.

Epidemiological studies indicate a relationship between water disinfectant by-products (DBP) and adverse pregnancy outcomes (APO) including neural tube defects. These studies suggest that fetal brain may be vulnerable to DBP during early stages of development. Therefore, we examined several molecular markers commonly known to indicate chemical-induced neurotoxicity during fetal brain development following prenatal exposure to the DBP; chloroacetonitrile (CAN). Pregnant mice, at gestation day 6 (GD6), were treated with a daily oral dose of CAN (25 mg/kg). At GD12, two groups of animals were treated with an i.v. tracer dose of [2-14C]-CAN. These animals were sacrificed at 1 and 24 h after treatment and processed for quantitative in situ micro-whole-body autoradiography. The remaining groups of animals continued to receive CAN. At GD18, control and treated animals were weighed, anesthetized, and fetuses were obtained and their brains were removed for biochemical and immunohistochemical analyses. Whole-body autoradiography studies indicate a significant uptake and retention of [2-14C]-CAN/metabolites (M) in fetal brain (cerebral cortex, hippocampus, cerebellum) at 1 and 24 h. There was a 20% reduction in body weight and a 22% reduction in brain weight of fetuses exposed to CAN compared to controls. A significant increase in oxidative stress markers was observed in various fetal brain regions in animals exposed to CAN compared to controls. This was indicated by a 3- to 4-fold decrease in the ratio of the reduced to oxidized form of glutathione (GSH/GSSG), increased lipid peroxidation (1.3-fold), and increased 8-hydroxy-2-deoxyguanosine levels (1.4-fold). Cupric silver staining indicated a significant increase in the number of degenerating neurons in cortical regions in exposed animals. In animals exposed to CAN there was increase in nuclear DNA fragmentation (TUNEL staining) detected in the cerebral cortex and cerebellum (2-fold increase in apoptotic indices). Caspase-3 activity in cerebral cortex and cerebellum of treated animals were also increased (1.7- and 1.5-fold, respectively). In conclusion, this study indicates that CAN/M crossed the placenta and accumulated in fetal brain tissues where it caused oxidative stress and neuronal apoptosis. These events could predispose the fetus to altered brain development leading to APO as well as behavioral and learning and memory deficits.

Neurological impairment in fetal mouse brain by drinking water disinfectant byproducts.

Developmental exposure to environmental chemicals may have detrimental effects on embryonic brains that could play a major role in the etio-pathology of fetal and adult neurological diseases. The exact mechanism by which prenatal exposures to environmental agents, such as drinking water disinfectant byproducts (DBP), cause neurological impairment in fetus is not known. Our objective is to examine the impact of prenatal exposure to DBP on fetal brain development. Pregnant CD-1 mice, at the sixth day of gestation (GD-6), received a daily (GD-6-GD-18) oral dose of chloroacetonitrile (CAN, 25 ppm), a member of DBP. To assess fetal brain uptake of CAN, several animals were injected with a tracer dose of 2-[(14)C]-CAN (333 microCi/kg, i.v.), at GD-12 and processed for quantitative in situ micro whole-body autoradiography (QIMWBA) at 1 and 24 h after treatment. The remaining animals continued receiving CAN until GD-18 when fetal brains were processed for biochemical determination of oxidative stress (OS) or prepared for histological examinations. The results indicate a rapid placental transfer and fetal brain uptake of 2-[(14)C]-CAN/metabolites in cortical areas and hippocampus. In treated animals 3-fold decrease in glutathione (GSH), 1.3-fold increase in lipid peroxidation and 1.4-fold increase in DNA oxidation were detected as compared to control. DeOlmos cupric silver staining of fetal brains indicated significant increase in cortical neurodegeneration in treated animals. Immunohistochemical labeling (TUNEL) of apoptotic nuclei in the cortices and choroid plexuses were also increased in treated animals as compared to control. In conclusion, CAN crosses the placental and fetal blood-brain barriers and induces OS that triggered apoptotic neurodegenration in fetal brain. Future studies will examine the molecular mechanisms of these events and its impact on neural development of offspring.

Species difference in the disposition of acrylonitrile: quantitative whole-body autoradiographic study in rats and mice.

Previous studies from this and other laboratories have indicated the role of species difference in acrylonitrile (VCN) toxicity and its metabolism to cyanide. Our recent studies also indicated a more pronounced elimination of VCN following oral as compared to i.v. administration. To further characterize the mechanism of these differences on the distribution of VCN, quantitative whole-body autoradiographic distribution and elimination studies were conducted at various time points (0.08, 8, 24, 48 h) following the administration of an equivalent i.v. dose of 2-[14C]-VCN to male Fischer rats and male CD-1 mice. Whole-body autoradiographs obtained from freeze-dried and acid-extracted sections of rats and mice demonstrated a rapid uptake of 14C in liver, lungs, spleen and bone marrow at early time intervals. Quantitatively, the uptake, retention and covalent interaction of 14C were higher in organs of rats as compared to mice, over 48 h. Mice eliminated 74% of the total administered dose of 2-[14C]-VCN (expired air 4%, urine 16% and feces 54%), while rats eliminated only 26% of the dose (expired air 2%, urine 4% and feces 20%). Species differences in VCN toxicity seem to be correlated with its rate of elimination. The distribution and elimination data demonstrated that mice divest VCN more rapidly than rats. The study also demonstrated that administration of VCN in rats resulted in covalent interactions and retention of 2-[14C]-VCN/metabolites in the tissues thus exerting more chronic toxicity to rats than to mice.

Effect of route of administration on the disposition of acrylonitrile: quantitative whole-body autoradiographic study in rats.

Previous studies on the effect of route of administration on acrylonitrile (VCN) toxicity in animal models indicated high rates of metabolism in rats that received an oral dose than those received an i.p. VCN dose. To evaluate the role of route of administration on the distribution of VCN, a quantitative whole-body autoradiography (QWBA) and elimination studies were conducted. Equimolar doses of 2-[14C]-VCN were administered i.v. or p.o. to male Fischer (F-344) rats. Time course of QWBA indicated a higher retention and covalent interaction of radioactivity in the liver, spleen and bone marrow of rats received an i.v. dose of 2-14C-VCN than those received a p.o. dose. Unlike rats that received an i.v. dose of VCN, the animals received an oral dose showed a high retention of 14C in blood, stomach and gastric mucosa. Differences were also reflected in 14C elimination in urine, feces and expired air. Animals treated orally with 2-[14C]-VCN excreted 61% of the administered radioactive dose (4% in expired air, 4% in urine and 53% in feces). Rats that received an i.v. dose of 2-[14C]-VCN, however, eliminated only 30% of the total radioactive dose (expired air 2%, urine 8% and feces 21%). The results indicate that metabolism, detoxication and elimination of VCN are more pronounced following oral administration as compared to i.v. route of administration. The study also demonstrates that the systemic administration of VCN enhances its covalent interaction and retention in the tissues thus cause more toxicity in these organs.

Acrylonitrile-induced neurotoxicity in normal human astrocytes: oxidative stress and 8-hydroxy-2'-deoxyguanosine formation.

Studies in our laboratory and others have indicated that acrylonitrile (VCN) induces acute and chronic neurotoxicity and brain tumors in animal models. Reduced glutathione (GSH) depletion was suggested as the initiator of oxidative stress in VCN-induced neurotoxicity. Astrocytes possess the majority of total brain GSH and express various immunological functions that are characteristic of the brain, including the secretion of cytokines. We hypothesized that astrocytes could be the primary target of VCN's adverse activities in the brain. Therefore, VCN-induced neurotoxicity was studied by exposing proliferating normal human astrocytes (NHAs) to various concentrations of VCN (25-400 muM). We assessed cell viability; levels of endogenous antioxidants, GSH, and catalase; levels of reactive oxygen species; and secretion of TNF- alpha, a cellular marker for oxidative stress and oxidative damage to nuclear DNA, after treatment with VCN. At VCN concentrations of 25 and 50 muM, the oxidative stress markers were unaffected and at least 85% of the cells were viable. Cell viability was significantly affected at 200 and 400 muM VCN (22-42% less than control, p <. 05). The results also indicated VCN-induced depletion of GSH and a concomitant increase in levels of oxidized GSH (GSSG). The levels of total GSH and GSSG in control and treated (400 muM VCN) cells were 37 and 2, respectively. There was a significant upregulation of catalase activity (21% more than control, p <. 05) at 100 muM of VCN and a downregulation at 400 muM (40% lower than control, p <. 05). A dose-dependent, significant increase in the formation of reactive oxygen species was observed at 200 to 400 muM of VCN. Also, an elevation (two- to three fold as compared to control, p <. 05) in oxidative damage to DNA was observed at these concentrations of VCN. Increase in TNF- alphasecretion (28% higher than control, p <. 05) was observed at 400 muM VCN. Therefore, redox imbalance in astrocytes may play a major role in VCN-induced neurotoxicity, which is indicated by compromised antioxidant defense mechanisms, such as depletion of GSH, increase in GSSG, inhibition of catalase, and increase in the formation of reactive oxygen species and TNF- alphasecretion, resulting in DNA oxidation.

Effect of an orally administered antacid agent containing aluminum hydroxide and magnesium hydroxide on abomasal luminal pH in clinically normal milk-fed calves.

OBJECTIVE: To determine the effects of a commercially available orally administered antacid agent containing aluminum hydroxide and magnesium hydroxide on abomasal luminal pH in clinically normal milk-fed calves. DESIGN: Randomized trial. ANIMALS: 5 male dairy calves. PROCEDURE: Throughout the study, calves were fed milk replacer at 7:30 AM and 7:30 PM. Cannulae for pH electrodes were placed in the abomasal body and pyloric antrum. Treatments consisted of oral administration of a high (50 ml) or low (25 ml) dose of the antacid agent and oral administration of milk replacer alone (control). Antacid was given at 7:30 AM, 3:30 PM, and 11:30 PM, and luminal pH was monitored continuously for 24 hours, beginning 15 minutes before administration of the first dose of antacid. RESULTS: Administration of the first dose of antacid at the time of the morning feeding resulted in an increase in mean abomasal body luminal pH of < 1 pH unit, whereas administration of the second and third doses of the antacid caused transient (< 3 hours) increases in mean luminal pH of approximately 1.5 (low dose) and 2.5 (high dose) pH units. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that clinically normal milk-fed calves given a commercially available antacid agent, PO, will have a transient increase in abomasal luminal pH. Such agents may, therefore, have a role in the treatment of abomasal ulceration in calves; however, the long-term effects of orally administered antacid agents in milk-fed calves and the clinical efficacy of such agents in treating abomasal ulceration remain to be determined.