Effects of furosemide and tadalafil in both conventional and nanoforms against adenine-induced chronic renal failure in rats

BACKGROUND

Chronic renal failure (CRF) is a progressive loss of renal function that lead to reduced sodium filtration and inappropriate suppression of tubular reabsorption that ultimately leads to volume expansion. The aim of this study was to study the efficacy of furosemide and tadalafil nanoforms compared to conventional forms against adenine-induced CRF rat-model.

METHODS

Addition of 0.75% adenine to the diet of rats for 4 weeks gained general acceptance as a model to study kidney damage as this intervention mimicked most of the structural and functional changes seen in human chronic kidney disease Urine analysis, histopathological changes and immunohistochemical expression of caspase-3 and interleukin-1 beta (IL-1β) in renal tissues were performed.

RESULTS

Our results showed that the combination of tadalafil and furosemide using conventional and nanoparticle formulations had better renoprotective effect than individual drugs. This was demonstrated by improvement of urinary, serum and renal tissue markers as indicative of organ damage. This was also reflected on the reduction of tubular expression of kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL). Immunohistochemical studies showed that the deteriorated renal cellular changes indicated by increased expression of caspase-3 and IL-1β were greatly improved by the combined treatment particularly with the nanoforms.

CONCLUSIONS

The nanoforms of both furosemide and tadalafil had greater renopreventive effects compared with conventional forms against adenine-induced CRF in rats.

Mapping the effect of drugs on ACE2 as a novel target site for COVID-19 therapy

Angiotensin converting enzyme 2 (ACE2) has potentially conflicting roles in health and disease. COVID-19 coronavirus binds to human cells via ACE2 receptor, which is expressed on almost all body organs. Boosting the ACE2 receptor levels on heart and lung cells may provide more cellular enter to virus thereby worsening the infection. Therefore, among the drug targets, ACE2 is suggested as a vital target of COVID-19 therapy. This hypothesis is based on the protective role of the drugs acting on ACE2. Therefore, this review discusses the impact and challenges of using ACE2 as a target in the current therapy of COVID-19.

Effect of stevia aqueous extract on the antidiabetic activity of saxagliptin in diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Stevia rebaudiana Bertoni is a perennial herb that belongs to the Asteraceae family. It is a natural sweetener plant known as "Sweet Leaf", "Sweet Herbs" and "Honey Leaf", which is estimated to be 300 times more sweetening than sugar cane. Stevia has been used as a traditional treatment for diabetes in many countries for hundreds of years. Several animal studies referred to the antihyperglycemic activity of stevia. However, the combined use of stevia with saxagliptin has not been studied so far, so this study has been done. The aim of the present study was to evaluate the antihyperglycemic effect of stevia alone and in combination with saxagliptin.

MATERIALS AND METHODS

Diabetes was induced in rats by i.p. injection of streptozotocin and nicotinamide. Animals were divided into five groups, each contains eight rats. Group I: included negative controland group II: included diabetic control that received saline. Group III: included diabetic rats that received 400 mg/kg/day stevia aqueous extract. Group IV: included diabetic rats that received saxagliptin 10 mg/kg/day. Group V: included diabetic rats that received stevia 400 mg/kg + saxagliptin 10 mg/kg. Food and water intake were measured daily while body weight was measured weekly. After 3 weeks animals were sacrificed and blood and tissue samples were collected. Fasting blood glucose (FBG), serum insulin, serum dipeptidylepeptidase-4 (DPP-4), TC, TGs, LDL, HDL, GSH and MDA were measured in treated and control rats by colorimetric and ELISA methods.

RESULTS

Both stevia and saxagliptin significantly reduced food, water intake, body weight and FBG. Stevia with saxagliptin produced more significant decrease in FBG. While serum insulin increased significantly in stevia, saxagliptin treated groups and their combination. Serum DPP-4 decreased significantly in all treated groups, concerning lipid profile, stevia and saxagliptin notably lowered TC, TGs, and LDL and increased HDL. Both stevia and saxagliptin remarkably decreased MDA and increased GSH compared to diabetic rats. In addition, stevia significantly improved the antidiabetic effects of saxagliptin.

CONCLUSION

Stevia has an antihyperglycemic effect and could enhance the antidiabetic activity of saxagliptin. DPP-4 attenuation, antihyperlipidemic and antioxidant activity as well as improvement of insulin sensitivity may be involved in the antidiabetic action of stevia.

Optimizing the Use of Hydroxychloroquine in the Management of COVID-19 Given Its Pharmacological Profile

After the global pandemic of the new coronavirus, its rapid spread and many victims, it is necessary to find an effective vaccine or drugs to overcome it. Most specialists consider that repositioning some medications is the best, fastest and most reliable option for treating patients with the new coronavirus without delay. One of these drugs was an old antimalarial drug, hydroxychloroquine. The current review aimed to explore its potential mechanism, as well as its pharmacokinetics and toxicity, in an attempt to suggest a treatment protocol for its use in treating the COVID-19 virus effectively and safely. This study reviewed the published references on the popular search engines as well as the reference books regarding the pharmacological effects of HCQ. The results of this study suggested the following practical guidelines to optimize HCQ efficacy and safety in the management of COVID-19. HQC should be used as early as possible, i.e., once the viral infection is confirmed or suspected. A loading dose is recommended to be given in 3-4 divided doses to minimize cardiac toxicity. Maintenance daily dose (divided into two doses), should be continued until complete remission. Precautions, drug-interaction, contraindications, variable metabolic pathways in the particular population should be considered. This study suggests more clinical trials regarding the use of HCQ in the management of early identified COVID-19 patients under close medical observation to minimize HCQ cardiac toxicity.  

Resveratrol as an effective adjuvant therapy in the management of rheumatoid arthritis: a clinical study

Resveratrol (RSV), a naturally occurring polyphenol, has been found to have potent antioxidant, anti-inflammatory, and anticancer effects. Recently, RSV was reported as a new potential agent to suppress inflammation of collagen-induced arthritis in a mouse model. Nevertheless, the clinical benefits of RSV in the management of rheumatoid arthritis (RA) were not studied. This randomized controlled clinical trial aims to shed some light on the therapeutic benefits of RSV in the treatment of RA in patients with different stages of the disease activity. In this randomized controlled clinical trial, 100 RA patients (68 female, 32 male) were enrolled randomly and divided into two groups, each of 50 patients: an RSV-treated group that received a daily RSV capsule of 1 g with the conventional treatment for 3 months and a control group that just received the regular treatment. The clinical and biochemical markers of RA in both groups were assessed. It was found that the clinical markers (i.e., the 28-joint count for swelling and tenderness) and the disease activity score assessment for 28 joints were significantly lowered in the RSV-treated group. Moreover, serum levels of certain biochemical markers (i.e., C-reactive protein, erythrocyte sedimentation rate, undercarboxylated osteocalcin, matrix metalloproteinase-3, tumor necrosis factor alpha, and interleukin-6) were also significantly decreased in RSV-treated patients. The current study suggests the addition of RSV as an adjuvant to the conventional antirheumatic drugs.

Vitamin K homologs as potential biomarkers for disease activity in patients with rheumatoid arthritis

The aim of this study was to evaluate the possible role of vitamin K homologs as potential biomarkers for disease activity in patients with rheumatoid arthritis (RA). In this study, 42 patients with RA and 40 healthy controls were enrolled. Serum levels of vitamin K homologs were measured using a high-performance liquid chromatography-fluorescence method. Different biochemical and clinical markers for disease activity were measured and correlated with serum levels of vitamin K homologs. There were no significant differences between RA patients and healthy subjects in demographic data. Patients with RA showed significantly higher levels of biochemical markers compared with healthy subjects (p < 0.001). These markers included rheumatoid factor (RF), anticyclic citrullinated polypeptide (anti-CCP), undercarboxylated osteocalcin (ucOC), matrix metalloproteinase (MMP-3), C-reactive protein (CRP), and disease activity score assessing 28 joints with erythrocyte sedimentation rate (DAS28-ESR). In addition, serum levels of vitamin K homologs were reduced in RA patients, and the levels of menaquinone-4 (MK-4) and menaquinone-7 (MK-7) were moderately to strongly inversely correlated with the clinical articular features in RA patients, whereas phylloquinone (PK) levels were weakly correlated. Serum levels of MK-4, MK-7 and PK were strongly inversely correlated with ucOC, MMP-3 and DAS28-ESR in RA patients. In contrast, serum levels of MK-4, MK-7 and PK were weakly correlated with CRP, RF and anti-CCP. These results suggest that serum levels of vitamin K homologs may be considered as potential biomarkers for disease activity. In addition, the results confirm the role of vitamin K deficiency in the etiology of RA.

Effect of Ketamine on Cocaine-Induced Immunotoxicity in Rats

The abuse of cocaine (COC) with ketamine (KET) is currently popular among young drug abusers and has been associated with increased risk of human immunodeficiency virus (HIV) infection. The effect of subacute exposure to COC and KET alone and in combination on the immune system was assessed in adult male Sprague-Dawley (SD) rats. To simulate the route and mode of human exposure, rats were treated with COC alone (5 mg/kg, IV), KET alone (100 mg/kg, PO) or KET followed immediately by COC (same doses and routes of administration) once-a-day for 7 consecutive days. Rats were sacrified 30 minutes following the last treatment. Total circulating leukocyte and lymphocyte counts were decreased with relative neutrophilia, whereas immunoglobulin M (Ig M) antibody response to sheep erythrocytes (SRBCs) was increased in animals treated with COC. Moreover, treatment with COC alone increased serum interleukin-10 (IL-10) concentration; however, it did not affect serum interferon gamma (INF-γ) concentration. Spleen histology showed hyperplasia of white pulp whereas thymus gland demonstrated mild cortical degeneration. On the other hand, KET treatment did not produce any significant change of any of these parameters. However, when coadministered with COC, significant reduction of bodyweight, spleen/bodyweight, and thymus/bodyweight ratios with degeneration of splenic white pulp and thymic cortex occurred. Moreover, the primary immunoglobulin response to SRBC and serum IL-10 concentration were decreased without significant change in serum IFN-γ or circulating leukocytic counts. COC caused a significant increase in serum corticosterone concentration that KET effectively prevented. On the other hand, a significant increase in plasma and tissue concentrations of norcocaine (NC) resulted following KET and COC administration in combination. Daily SKF-525A pretreatment at a dose of 30 mg/kg, IP, for 7 days 1 hour prior to KET and COC in combination effectively reversed the effects of this combination on body weight, organ/bodyweight ratios, histopathology, and serum Ig M and IL-10 concentrations without affecting leukocytic counts. On the other hand, SKF-525A pretreatment did not change the immunomodulatory effects of COC compared to non-pretreated animals. The results suggest that COC-induced immunomodulation most likely occurred through neuroendocrinal mechanisms. On the other hand, enhanced oxidative metabolism of COC in the presence of KET-induced immunosuppression.

Reactive oxygen and nitrogen species in patients with rheumatoid arthritis as potential biomarkers for disease activity and the role of antioxidants

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) have distinct contribution to the destructive, proliferative synovitis of rheumatoid arthritis (RA) and play a prominent role in cell-signaling events. However, few studies had clarified the role of individual ROS and RNS in the etiopathogenesis of RA. To date, most of the studies were concerned with the measurement of the total oxidative and nitrative stress levels in RA. The aim of this study was to monitor the levels of individual ROS and RNS to emphasize the role that each plays in the pathogenesis of RA and their usefulness as possible biomarkers for the disease activity. In addition, the effect of an antioxidant (ascorbic acid), added to the treatment regimen, on the levels of ROS, RNS and disease activity has been evaluated. Forty-two Saudi RA patients and 40 healthy controls of both genders were included in this study. Serum levels of six different ROS and three different RNS were measured using specific fluorescent probes. The ROS included the hydroxyl radical ((•)OH), the superoxide anion (O2(•-)), hydrogen peroxide (H2O2), the singlet oxygen ((1)O2), the hypochlorite radical (OHCl(•)), and the peroxyl radical (ROO(•)). The RNS included nitric oxide (NO(•)), nitrogen dioxide (ONO-) and peroxynitrite (ONOO-). The main clinical and biochemical markers for disease activity were assessed and correlated with ROS and RNS levels. The clinical markers included the 28 swollen joint count (SJC-28), the 28-tender joint count (TJC-28), morning stiffness and symmetric arthritis, in addition to the disease activity score assessing 28 joints with erythrocyte sedimentation rate (DAS28-ESR). The biochemical markers included undercarboxylated osteocalcin (ucOC), matrix metalloproteinase (MMP-3), ESR, C-reactive protein (CRP), rheumatoid factor (RF) and anticyclic citrullinated polypeptide (Anti-CCP). Ascorbic acid (1mg/day) was added as an antioxidant to the regular treatment regimen of RA patients for two months, and the levels of ROS and RNS, as well as disease activity were re-evaluated. The results have shown significant higher serum levels of individual ROS and RNS in RA patients compared with healthy subjects. Moreover, this study might be the first to report strong positive correlations between most of the reactive species and the clinical and biochemical markers of RA. Interestingly, the addition of ascorbic acid had significantly reduced the levels of all ROS and RNS in RA patients. In conclusion, the role of oxidative and nitrative stress in the pathogenesis of RA has been confirmed by this study. Serum levels of ROS and RNS may effectively serve as biomarkers for monitoring disease progression. Finally, the addition of an antioxidant, such as ascorbic acid, in the management of RA may be of a great value.

Protective effect of citicoline against aluminum-induced cognitive impairments in rats

The potential protective effect of citicoline on aluminum chloride-induced cognitive deficits was investigated in rats. In a Morris water maze, administration of aluminum chloride to rats for 90 days resulted in increased escape latency to reach the platform and decreased swimming speed in acquisition trials. Similarly, in probe trials, the time required to reach the hidden platform was increased and the time spent in the target quadrant was reduced. Also, administration of aluminum chloride to rats for 90 days increased the reference and working memory errors and time required to end the task in the radial arm maze. In addition, this treatment decreased the step-through latency in the passive avoidance test. Concurrently, treatment of rats with aluminum chloride for 90 days increased hippocampal glutamate, malondialdehyde, and nitrite levels and decreased intracellular reduced glutathione level. In the citicoline-treated group, aluminum chloride-induced learning and memory impairments as assessed by the Morris water maze, radial arm maze, and passive avoidance tests were inhibited. At the same time, treatment of rats with citicoline prevented the biochemical alterations induced by aluminum chloride in the hippocampus. It can be concluded that elevation of hippocampal glutamate level with consequent oxidative stress and nitric oxide (NO) overproduction may play an important role in aluminum-induced cognitive impairments. Also, our results suggest, for the first time, that citicoline can protect against the development of these cognitive deficits through inhibition of aluminum-induced elevation of glutamate level, oxidative stress, and NO overproduction in the hippocampus.

Oral cocaine produces dose-related hepatotoxicity in male mice

Cocaine remains a widely abused substance. While most addicts take cocaine intranasally, a considerable number abuse cocaine by mouth. It has been assumed that after oral exposure cocaine is hydrolyzed in the stomach rendering it ineffective. This study investigated the effect of orally administered cocaine on liver function and integrity as well as its effect on liver and blood antioxidative enzymes. Male CF-1 mice were orally administered either 0, 5, 10 or 20 mg cocaine/kg body weight and sacrificed 24 h after the last treatment. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured as markers of liver injury. Blood and liver glutathione (GSH) levels were determined as well as the activities of glutathione peroxidase (GPx) and catalase (CAT). In addition, the activity of liver glutathione reductase (GRx) was also measured. The results demonstrated that oral cocaine caused hepatotoxicity in a dose dependent manner. Serum ALT and AST were elevated while blood GSH concentration decreased in all cocaine treated animals. In addition, there was a significant dose dependent decrease in the activities of GPx and CAT in blood and liver of cocaine treated animals. However, hepatic GSH content and GRx activity manifested a significant increase, particularly in the group, which received 20 mg/kg cocaine. This study is the first to demonstrate that cocaine-induced hepatotoxicity results following the oral route of administration.

Oral bioaccessibility of trivalent and hexavalent chromium in soil by simulated gastric fluid

Chromium is found in soil from natural sources and anthropogenic activities. The ingestion of soil contaminated with chromium especially by children can have toxic consequences. Therefore, it is important to quantify the oral bioaccessibility of chromium in chromium in contaminated soil. In this study, chromium-51 as chromic (III) chloride and sodium chromate (VI), was mixed with an Atsion sandy soil and a Keyport clay soil and stored for 4 mo at either 21-25 degrees C or 2-4 degrees C. Utilizing simulated gastric conditions, the oral bioaccessibility of chromium in soil was determined. When the effects of soil on the bioaccessibility of chromium were compared, the data revealed the the bioaccessibility of chromium (III) from the clay soil was significantly lower than from the sandy at 21-25 degrees C. However, at 2-4 degrees C, more chromium (III) was extracted by synthetic gastric fluid from the clay soil than from the sandy soil. Temperature was also a factor as evidenced by the higher bioaccessibility of chromium (IV) in the sandy soil at 2-4 degrees C and of both chromium species in the clay soil at the same temperature. Reduction of the soluble chromium (VI) chemical to the nonsoluble chromium (III) compound in the acidic soils by naturally occurring organic matter in soil would explain the lower bioaccessibilty of chromium (VI) at 21-25 degrees C. At 2-4 degrees C, the data indicate that the rate of chromium (VI) reduction to chromium (III) was slowed. Although the results of this study are limited to one low concentration of chromium (III) and chromium (VI) and indicate that the bioaccessibility of chromium in soil can range between 18% and 72%, the data also suggest that there may be a potential health hazard from oral exposure to chromium in heavily contaminated sites. Therefore, more extensive research should be conducted to determine if thes findings can be extended to environmentally relevant concentrations.

The role of enzyme induction and inhibition on cypermethrin hepatotoxicity

Cypermethrin at different concentrations (100, 200, 400 and 800 ng ml(-1)) was incubated with a primary culture of rat hepatocytes. Cypermethrin was cytotoxic to rat hepatocytes at concentrations of 200 ng ml(-1)or greater. Toxicity was measured by a decrease in cell viability and leakage of ALT and AST enzymes into the culture medium. The role of cytochrome P450 in the hepatotoxicity of cypermethrin insecticide was investigated in fresh hepatocytes isolated either from phenobarbital pretreated rats or control rats and coincubated with SKF525A. Pretreatment with phenobarbital strongly protected the hepatocytes against the cypermethrin induced loss of cell viability percentage and increased enzyme leakage percentage. Coincubation of the hepatocytes with SKF525A, a well-known cytochrome P450 inhibitor, substantially potentiated the effect of cypermethrin on cell viability and enzyme leakage. These results suggest that the cytocidal hepatotoxicity of cypermethrin in primary hepatocyte culture depends on its parent compound and phenobarbital, as a cytochrome P450 inducer, could be of therapeutic value.

Geographic information systems as a tool for control program management for schistosomiasis in Egypt

During a 4-year study a geographic information system (GIS) risk model was constructed for predicting the relative risk of schistosomiasis in Kafr El-Sheikh governorate, Egypt. A 1-year 1990-1991 time series on diurnal temperature difference (dT) prepared from the advanced very high resolution radiometer (AVHRR) sensor on the NOAA-11 satellite was used to develop a regional risk model for the Nile delta based on thermal-hydrological domains. A May 15, 1990 Landsat TM scene (path 177, Row 38) was used to develop a local 'village-scale' environmental risk model based on higher resolution satellite sensor data (30 m picture element size at earth surface). Four of ten classes derived from a tasseled cap (Tcap) transformation of the Landsat TM scene were shown to be significantly related to a 5-year Schistosoma mansoni prevalence database from the Ministry of Health. A risk model was developed based on dT and the proportional area of the four Tcap classes in 5 km(2) buffer zones centered on rural health unit (RHU) reporting units. Available historical data on S. mansoni and its snail host Biomphalaria alexandrina, as well as recent field collected data were gathered and incorporated as separate themes. Model validation was done using data collected on snail population bionomics-infection rates, water quality, underground water table and cercariometry at 13 hydrologically representative sites. The role of soil type, water table and water quality was studied at 79 of 154 rural health unit sites. The model permitted retrieval of relevant data by RHU point location. For the first time in Egypt, the Kafr El-Sheikh GIS schistosoma prediction model can support MOH efforts to make more accurate control program decisions based on environmental predilection sites of endemic Schistosomiasis mansoni.

Effects of omeprazole on ethanol lesions

Male Sprague-Dawley rats were used to study the effects of omeprazole on normal and ethanol damaged gastric mucosa, and to estimate plasma gastrin levels following the administration of omeprazole for 2 weeks. The dosage of omeprazole was 50 mg/kg body weight, once daily via gavage. In omeprazole treated animals, serum gastrin levels showed statistically significant increases compared with the control and ethanol treated animals. Our results indicate that omeprazole has no protective effect on ethanol-induced alterations in gastric mucosa and, in fact, appears to produce worsened lesions. In achlorohydric doses, omeprazole can induce significant gastrin levels with consequent hypertrophy and hyperplasia of enterochromaffin-like cells and somatostatin cells. It is believed that this powerful drug should be reserved for patients who are refractory to standard H(2)-receptor antagonist therapy.

In vitro penetration of soil-aged mercury through pig skin

The dermal bioavailability of mercury "aged" in soil for 3 mo was compared to that of pure mercury (without soil) and to mercury in brief contact with soil (16 h). Studies were conducted in vitro with [203Hg]mercuric chloride on dermatomed male pig skin by flow-through diffusion cell methodology. Less than 0.5% of the initial mercury dose penetrated through skin into receptor fluid after each treatment. The majority of pure mercury became covalently bound to skin. However, a short contact time with either an Atsion (sandy) or Keyport (clay) soil significantly decreased the total penetration of mercury (sum of receptor fluid and skin) by 40%. After aging, a 95% reduction in total penetration was observed for the compound relative to chemical without soil. Both soils bind mercury more strongly with time, as evidenced by larger quantities of radioactivity in soil and smaller amounts in skin decontaminate after aging than in soil for 16 h. Decreased mercury bioavailability with aging indicates lower health risk and reduced need for soil cleanup.

Teratogenic effect of ketamine and cocaine in CF-1 mice

Pregnant CF-1 mice were used to study the teratogenic effect of ketamine and cocaine, alone and in combination. The dose of ketamine was 50 mg/kg and that of cocaine was 20 mg/kg, given intravenously (tail) once daily (these doses of ketamine and cocaine are comparable to doses used by addicted humans). Treatment was started from day 6 to day 15 of gestation, and dams were sacrificed on day 18. There were significant decreases in the fetal weight and length in the combined group. Skeletal defects such as incomplete ossification of skull bones and vertebrae were observed in both the cocaine and combined group, compared with the control. An increased frequency of cerebral and abdominal hemorrhages as well as hydrocephalus and hydronephrosis was observed in the combined group. This study showed that fetal exposure to ketamine and cocaine in combination was more teratogenic than each drug alone in CF-1 mice.

Pharmacokinetics of acrylamide after oral administration in male rats

Acrylamide (AMD) is a commonly used industrial chemical. However, it produces a dying back type of peripheral neuropathy in animals and man. This study was performed to investigate the pharmacokinetics of AMD after oral administration at 50 mg/g ([1-(14)C]AMD) in male Sprague-Dawley rats. Absorption from the gastrointestinal tract was rapid and radioactivity was detected in blood 5 min post-administration. The peak plasma concentration occurred 38 min after administration and was equivalent to 47 μg/ml. The elimination pattern for plasma was fitted to a one-compartment model with 6 h half-life. However, in the blood the elimination pattern was fitted to a two-compartment model with 7.93 and 374 h for distribution and elimination phases, respectively. Tissue concentrations of radioactivity determined at 28 and 144 h post-administration differed substantially. After 28 h the highest activity was in the gastric content, followed by stomach, lung, bone marrow and skin, while after 144 h the order of total radioactivity was lung>bone marrow>esophagus. The activities in the rest of the organs in both experiments were very low. The excretion study revealed that the kidney is the major route of elimination and the majority of radioactivity in urine was excreted during the first 12 h. The feces contained approximately 10% of the administered dose after 144 h. This study indicated that AMD is rapidly absorbed from the rat's gastrointestinal tract, distributed and eliminated from the body. AMD bound but did not accumulate in the erythrocytes or the neural tissues.

Effect of alcohol and/or cocaine on blood glutathione and the ultrastructure of the liver of pregnant CF-1 mice

Alcohol and cocaine are abused by the general population as well as by pregnant women. Since alcohol and cocaine are hepatotoxic, pregnant mice were used to study the effect of alcohol and/or cocaine on alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and on liver ultrastructure. Also, blood glutathione (GSH) and GSH related enzymes such as glutathione reductase (GSH-Rx) and glutathione peroxidase (GSH-Px) were studied. The mice were treated with 0.6 g/kg ethanol twice daily via gavage and/or 20 mg/kg of cocaine hydrochloride intravenously once daily. The treatment was from day 6 to 15 of gestation and these studies were performed at day 18. Our results indicated a significant increase in AST level after treatment with ethanol alone or in combination with cocaine. The blood GSH levels decreased significantly in all the treated groups compared to the control. The activity of GSH-Px was significantly decreased only in the ethanol and cocaine combination group compared to the control. Histopathological studies indicated that co-administration of ethanol and cocaine lead to a significant potentiation in liver toxicity as indicated by increased fatty infiltration.

Ethanol does not increase the hepatotoxicity of cocaine in primary rat hepatocyte culture

Rat hepatocytes were utilized to investigate the role of cocaine metabolism and the contribution of ethylcocaine formation to cocaine-induced liver damage. Hepatocytes were prepared from rats pretreated with saline, phenobarbital or ethanol and exposed to cocaine, ethanol, or their combination. Hepatotoxicity was assessed by lactate dehydrogenase (LDH) leakage and was correlated with cocaine metabolism which was assessed quantitatively using HPLC. Only phenobarbital-pretreatment produced increases in LDH leakage from cultures exposed to cocaine. This increase in LDH release occurred simultaneous to a decrease in benzoylecognine formation and a marked increase in norcocaine generation. Exposing cultures to ethanol alone did not result in LDH leakage from hepatocytes. Furthermore, including ethanol in cultures treated with cocaine did not enhance the LDH leakage produced by cocaine alone. This study confirms quantitatively that cocaine-induced hepatotoxicity is mediated through cocaine oxidative events and is enhanced by microsomal induction produced by phenobarbital. The finding that ethylcocaine formation was maximal in the ethanol-pretreatment group where no toxicity was observed suggests that ethylcocaine is not the agent responsible for the hepatotoxicity observed in this study.

Trials for control of ixodid ticks using pheromone acaricide tick decoys

Experimental application of Hyalomma dromedarii pheromone-impregnated in cyfluthrin (pyrethroid) decoys on experimentally infested camels revealed efficacy rate of 85.33%, while the control group showed normal pattern of tick engorgement. This study proved the rapid movement of males toward decoys and some males took the mounting position with such decoys. On the other side, the same decoys (H. dromedarii) when used on naturally infested cattle with Boophilus annulatus did not even disturb the Boophilus ticks indicating that B. annulatus contain specific pheromones which should be furtherly identified.

Kinetics and rat locomotor activity following cocaine and lidocaine administration

Cocaine abuse is a widespread problem in the USA. Illicit cocaine is usually never found in pure form but is adulterated with other agents, among which are the local anesthetics such as lidocaine. Adulteration of cocaine with another active agent allows the potential for various drug-drug interactions to occur. The presence of an additional active agent in illicit cocaine samples can complicate the pharmacological and toxicological responses elicited and possibly the mode of emergency medical care thereafter. When studying drug interactions, both the kinetic and dynamic aspects of each agent must be considered. This study investigated the plasma time course and tissue distribution of cocaine and lidocaine alone and in combination following a 5 mg kg(-1) intravenous injection in rats. The plasma time course of cocaine and lidocaine in combination did not differ from that seen when each drug was alone. Tissue contents were without change when administered alone or in combination at 5, 10 and 15 min following treatment. However, rats treated with cocaine and lidocaine in combination had significantly greater locomotor activity initially than animals treated with cocaine alone. The results suggest that cocaine and lidocaine interact on a pharmacodynamic basis without a change in the drug level of each agent.

Effect of propofol on perception of pain in mice: mechanisms of action

The latencies of pain threshold to different subhypnotic doses (12.5, 25 and 50 mg kg-1) of propofol, an anaesthetic, administered intraperitoneally (i.p.) into male mice were measured using a hot plate method. The possible mechanism of pain control by propofol was also investigated through blocking beta-endorphin receptors and measuring serum level of beta-endorphin. Morphine (1.5 mg kg-1; i.p.) was used as a reference of reduction of pain sensation. The results showed that propofol in doses of 25 and 50 mg kg-1 significantly (P < 0.01) increased the latency of pain threshold but a lower dose (12.5 mg kg-1) failed to produce any significant change. This indicates that propofol reduced pain and this effect is dose-dependent. Propofol prevents hyperalgesia produced by prostaglandin PGE2, (0.5 mg kg-1, i.p.; P < 0.01). Pretreatment with naloxone (1.0 mg kg-1, i.p.) abolished significantly (P < 0.01) the antinociceptive action of propofol. Furthermore, serum level of beta-endorphin was increased (P < 0.01) after propofol injection particularly at the peak time of propofol action. The serum level of corticosterone was also increased (P < 0.01) at the time of beta-endorphin release. It was concluded that propofol can control pain and this action may be centrally modulated through the opioid system rather than at the level of the spinal cord.

Hepatoprotective activity of thymoquinone in isolated rat hepatocytes

Thymoquinone, the active constituent of Nigella sativa, was tested in isolated rat hepatocytes as a hepatoprotective agent against tert-butyl hydroperoxide (TBHP) toxicity. TBHP (2 mM) was used to produce oxidative injury in isolated rat hepatocytes and caused progressive depletion of intracellular glutathione (GSH), loss of cell viability as evidenced by trypan blue uptake and leakage of cytosolic enzymes, alanine transaminase (ALT) and aspartic transaminase (AST). Preincubation of hepatocytes with 1 mM of either thymoquinone or silybin, which is a known hepatoprotective agent, resulted in the protection of isolated hepatocytes against TBHP induced toxicity evidenced by decreased leakage of ALT and AST, and by decreased trypan blue uptake in comparison to TBHP treated hepatocytes. Both thymoquinone and silybin prevented TBHP induced depletion of GSH to the same extent. Although thymoquinone protected the liver enzymes leakage, the degree of protection was less than that caused by silybin.

Effect of cypermethrin on isolated male and female rat hepatocytes

Cypermethrin is a synthetic pyrethroid that belongs to a group of insecticides with low mammalian toxicity but high insecticidal activity. The present study was designed to investigate the toxicity of cypermethrin on freshly isolated hepatocytes from male and female rats. Hepatocytes were harvested by a collagenase perfusion technique and were exposed to different concentrations of cypermethrin (100, 200, 400, or 800 ng/2 x 10(6) cells) for up to 2 h. Cell viability and the leakage of aspartate transaminase (AST) and alanine transaminase (ALT) were determined throughout the incubation period. The cell viability of the hepatocytes from male and female rats exposed to 400 ng and 800 ng was significantly reduced after 60 and 30 min of incubation, respectively. With cells from female rats, viability was also reduced upon exposure to 200 ng cypermethrin for 2 h. The decrease in cell viability was dose and time dependent. The leakage of ALT and AST was significantly increased with 400 and 800 ng concentrations at 60 and 30 min, respectively. ALT leakage from female hepatocytes was significantly increased at 60 min of incubation with the 200-ng dose, whereas 2 h of incubation was required for the leakage of ALT from the cells of male rats. The present data indicate that cypermethrin has toxic effects on male and female rat hepatocytes in a dose- and time-dependent manner. The data suggest that female rat hepatocytes may be more sensitive to the toxic effects of cypermethrin than male cells.

Influence of atenolol and/or metformin on glutathione and magnesium levels in diabetic rats

Recently there has been growing interest in studying the differences between different classes of antihypertensive drugs in preventing cardiovascular events in diabetic patients. Hypomagnesemia is common in diabetes mellitus, and correlates to its chronic complications and the associated alteration of the antioxidant enzyme activity. Depletion of reduced glutathione (GSH) in the blood has been demonstrated with myocardial injuries associating hypomagnesemia. A previous study has demonstrated a beneficial effect of metformin hydrochloride (Met), an antihyperglycemic drug, on both magnesium (Mg) and GSH levels in diabetic animals. The purpose of this study was to investigate the effect of oral atenolol, metformin (50 and 60 mg kg[-1] day[-1], respectively) and their combination for 14 days on Mg and GSH levels in blood, liver and heart of diabetic male Wistar rats, as these two parameters have been shown to be altered in diabetics and linked to myocardial ischemic injuries. The results of this investigation showed a state of low levels of Mg and GSH in both blood and liver of the diabetic animals. Treatment with atenolol alone did not change these levels significantly, however administration of metformin or atenolol/metformin increased significantly the GSH levels in both liver and blood, and returned the liver Mg content back to normal values.

Development and validation of a satellites based geographic information system (GIS) model for epidemiology of Schistosoma risk assessment on snail level in Kafr El-Sheikh Governorate

The aim of the present study was to test the accuracy of Advanced Very High Resolution Radiometer (AVHRR) satellite derived temperature difference (dT) maps as a guide for the suitability of the environment for local snail hosts and Schistosoma development-transmission at the village level. The study provided field validation data from 13 villages in Kafr El Sheikh in the Nile Delta that sites present in wet zones of low dT value have more abundant snail populations than that present in the drier zones with high dT values. Results suggest that lower dT values were associated with wetter hydrologic regimes related to the level of underground water table and that this is reflected in the abundance of snail populations and Schistosoma snail infection rates at the village level. Water quality parameters on pH salinity and dissolved oxygen were not correlated with presence of Schistosoma infected snails. Results indicate that abundance of snails and S. mansoni prevalence are related to thermal-hydrology domains associated with surface water, that habitat suitability is related to depth to water table and that regional hydrology characteristics that affect snail host habitat suitability (ie. wet, moist, dry or very dry) can be evaluated using AVHRR dT maps.

Decreased cocaine- and lidocaine-induced seizure response by dextromethorphan and DNQX in rat

The present study investigated the effect of dextromethorphan and 6,7-dinitroquinoxaline-2,3-dione (DNQX) pre-treatment on the development of cocaine- and lidocaine-induced seizures. The dopaminergic action of cocaine was also studied. The NMDA antagonist dextromethorphan and the non-NMDA (AMPA/kainate) antagonist DNQX both significantly decreased the intensity of the seizure response to intravenous convulsant doses of cocaine and lidocaine individually (20 mg/kg) and in combination (5 mg/kg each). The incidence of seizures in rats receiving cocaine or lidocaine individually was significantly reduced by pre-treatment with dextromethorphan but not DNQX. Haloperidol did not have an effect on the incidence or intensity of seizures induced by cocaine or lidocaine, alone or in combination. The results suggest that local anesthetic-induced convulsive seizures are mediated by excitatory glutamate transmission through both NMDA and non-NMDA receptor systems.

Role of ethanol exposure on cocaine metabolism in rat hepatocytes

Cocaine remains a widely abused illicit substance in our society. Cocaine hepatotoxicity has been linked to cocaine metabolism. Cocaine can undergo hydrolytic inactivation via plasma and hepatic esterases or it can be N-oxidized by cytochrome P-450 and FAD-containing monooxygenases. Ethanol is frequently used in combination with cocaine. The presence of ethanol can affect the metabolism of other agents, depending on the dose and duration of exposure. In this investigation, hepatocytes isolated from male Sprague-Dawley rats were utilized to study the effect of ethanol exposure on cocaine metabolism. Hepatocytes were isolated using a two-step collagenase perfusion system. Hepatocytes (2 x 10(6) cells ml(-1)) were exposed to cocaine, ethanol or the combination of cocaine and ethanol for a 2-h period in a shaking water-bath at 30 oscillations per minute maintained at 37 degrees C. Sodium fluoride (NaF) was added to aliquots of cells which were removed from the incubation following 30, 60 and 120 min. The cells were homogenized on ice and immediately extracted for the quantification of cocaine, benzoylecognine, norcocaine and ethylcocaine by HPLC. Quantitative analysis revealed that there was a time-dependent increase in the disappearance of cocaine from hepatocytes. The rate of cocaine disappearance was not changed when ethanol was included in incubations containing cocaine. However, in the presence of ethanol there was a difference in the quantities of cocaine metabolites produced. When ethanol was included in incubations containing cocaine, the formation of norcocaine and benzoylecognine was less than that formed in hepatocytes exposed to cocaine alone. Additionally, when hepatocytes were exposed to cocaine in combination with ethanol, the formation of ethylcocaine was linear with time. This study revealed that in the presence of ethanol, cocaine qualitative metabolism is altered.

Geographic information systems and the distribution of Schistosoma mansoni in the Nile delta

New computer-based sensor technology and geographic methods have led to emerging interest in use of satellite environmental assessment tools for design of disease control programs, especially for those that are vector borne. The long-range goal of work reported here by John Malone and colleagues on behalf of this Egyptian Ministry of Health-USAID Schistosomiasis Research Project team (Box 1) is to utilize data from sensor systems on board earth-observing satellites to develop more-sensitive disease-prediction and -control models. If successful, methods developed may provide a potentially vital capability for use by disease control program managers, particularly in less-developed countries, where mapping resources are not well advanced. Longer term, broader basic questions on the interaction of environment and disease in anticipation of predicted global climate change may be addressed. These studies focused on the lower Nile river basin of Egypt. The specific objective was to link data on environmental requirements for propagation and transmission of schistosomiasis with parameters measurable from space.

Cocaine and lidocaine in combination are synergistic convulsants

The abuse of cocaine has dramatically increased in the recent decade. Cocaine obtained on the illegal market is rarely found in pure form. Most often it is adulterated with various substances, especially other local anesthetics. Lidocaine is one of the most common local anesthetics employed for adulteration of illicit cocaine. Toxicity due to the simultaneous ingestion of cocaine and lidocaine has been reported. Acute toxicity to cocaine and other local anesthetics is manifested in central nervous system aberrations, such as seizures and convulsions. This study investigated the convulsant potency of cocaine and lidocaine alone and in combination. Rats were administered intravenous injections of 5 mg/kg or 20 mg/kg of cocaine or lidocaine alone and in combination in equal proportion. Seizure activity and intensity were evaluated. The plasma concentration and brain content of each agent was also determined at the time of toxicity. The administration of 5 mg/kg of each drug alone did not yield seizure activity. However, the concomitant administration of 5 mg/kg of both cocaine and lidocaine produced a seizure response nearly equal to that produced after administration of 20 mg/kg of cocaine alone. Diazepam pre-treatment successfully antagonized the seizures induced by cocaine and lidocaine and raised the seizure threshold dose for the combination treatment by approximately four fold. The results suggest that cocaine and lidocaine interact synergistically to increase seizure activity and that the nature of this response occurs in part through a depression of inhibitory neuronal transmission.

Teratogenic effect of diphenylhydantoin and/or fluphenazine in mice

Diphenylhydantoin and fluphenazine are two drugs that act on the central nervous system. Many patients are taking these two drugs together and sometimes during pregnancy. Therefore, this study was conducted to determine the safety or the teratogenic effect of these two drugs alone or in combination. Pregnant mice were administered diphenylhydantoin at 50 mg kg-1 body wt. and/or fluphenazine at 1 mg kg-1 body wt. by gavage. The control group was administered the vehicle of diphenylhydantoin (water containing 0.6% alcohol). All pregnant animals were treated from day 6 to day 15 of gestation. The females were sacrificed on day 18. A significant reduction of fetal weight and length was found in all treatment groups when compared to the control. As regards to skeletal anomalies, it was found that the incidence of incomplete ossification of sternebrae and skull bones was significantly increased in the combination group when compared to the control group. Examination of visceral anomalies showed that dilated cerebral ventricles were observed in the fluphenazine-treated group, with the incidence of these malformations increasing significantly when diphenylhydantoin was administered in combination with fluphenazine. In summary, the administration of diphenylhydantoin and fluphenazine in combination was shown to be more teratogenic than each drug alone.

Development and validation of a high-performance liquid chromatography method for the determination of cocaine, its metabolites and lidocaine

Street cocaine varies in purity and is often adulterated with various compounds. Some of these additives, such as lidocaine, may increase the toxicity of cocaine. A new precise, accurate and sensitive reversed-phase high-performance liquid chromatography method for the determination of cocaine, its metabolites and lidocaine in plasma samples has been developed and validated. This assay employed a phosphate-buffered aqueous mobile phase (pH 6.0) with an organic component consisting of acetonitrile and methanol and a C-18 column as the stationary phase. Minimum detection limits were 1 ng ml-1 for cocaine, 2.5 ng ml-1 for ethylcocaine and 5 ng ml-1 for benzoylecgonine, norcocaine, norethylcocaine and lidocaine. Linearity was demonstrated over a broad range of concentrations in plasma, with good sensitivity for cocaine and cocaine derivatives.

Safety evaluation of benzophenone-3 after dermal administration in rats

Benzophenone-3 (BZ-3) is a category 1 (over-the-counter) product approved by the US Food and Drug Administration (FDA) for use as a sunscreen agent in medicine, cosmetics, industry, and agriculture. This is due to its ability to absorb and dissipate ultraviolet light in a harmless manner, thus protecting human skin and products from UV irradiation. This study investigated the safety of BZ-3 after repeated administration. BZ-3 in ointment base was applied at a dose of 100 mg/kg body wt. twice daily, for 4 weeks to the skin of male Sprague-Dawley rats. Body weight, organ to body weight ratios, hematological, and clinical chemistry parameters were not effected. Pathological examination revealed no significant changes between control and treated animals. No gross external abnormalities were observed. Both in vivo and in vitro blood glutathione (GSH) levels were effected by BZ-3 treatment. However, after 60 min of incubation, a reversal of this effect was observed in the treatment group as blood GSH levels approached normal levels. Furthermore, investigation of GSH-reductase and peroxidase with time indicated an increase in GSH-reductase activity at 60 and 90 min with no effect on GSH-peroxidase. Pre-treatment with phenobarbital modulated the metabolic disposition of BZ-3. There was an increase in the formation of the hydroxy metabolites but not the O-dealkylated form. This study suggests that BZ-3 is not toxic to rats when applied dermally at a dose of 100 mg/kg body wt. for 4 weeks.

Effect of metformin on glutathione and magnesium in normal and streptozotocin-induced diabetic rats

Recently there has been growing interest in magnesium deficiency and its correlation with coronary artery disease, chronic complications of diabetes mellitus and antioxidant enzyme activity. Hypomagnesemia is a common association of diabetes mellitus, and the blood glutathione (GSH) level is significantly lower in both conditions. Metformin (Met), 'an oral antihyperglycemic drug' frequently used in the management of diabetes mellitus outside the USA, has been shown to have an insulin-like action. The purpose of this study was to investigate the effect of oral administration of Met (60 mg kg(-1)) for 14 days on GSH and magnesium levels in blood, liver and heart of normal and streptozotocin-induced diabetic Wistar rats. Diabetes was induced by an i.p. injection of streptozotocin (60 mg kg(-1)). Our results showed that Met did not affect fasting serum glucose concentration in non-diabetic animals but reduced it significantly in diabetic animals. Serum and liver magnesium levels were significantly decreased in the untreated diabetic group compared with the normal group. Treatment with Met improved liver magnesium concentration in the diabetic group only. It has no effect on serum magnesium in diabetic or non-diabetic rats. Heart magnesium levels showed non-significant changes in all groups. In diabetic animals a significant decrease of GSH in both blood and liver was observed. Treatment with Met increased these levels significantly, with a similar effect on GSH levels in non-diabetic rats. There were no significant changes in heart GSH levels in any of the groups. This study demonstrates that oral Met therapy improves the altered levels of magnesium and GSH in diabetic rats.

Comparison between oral and dermal bioavailability of soil-adsorbed phenanthrene in female rats

Phenathrene is a major coal tar component found in hazardous waste disposal sites. The purpose of this study was to evaluate the extent to which phenanthrene adsorption to either of 2 different soils affects the manner in which phenanthrene is subsequently handled in orally and dermally exposed adult female rats. Absorption from the gastrointestinal tract was relatively rapid for all treatments with maximum plasma concentration of radioactivity occurring within 1 h following oral administration. After dermal application, the time to reach maximum plasma concentration (12 h) was the same in all 3 phenanthrene treatment groups although sandy soil lowered the area under the plasma concentration time curve (AUC) compared to the pure and clay soil groups. Dermal exposure increased absorption half-lives 8-fold compared to oral exposure in the pure group and 15-fold in each of the soil groups. After oral or dermal treatment with phenanthrene alone or adsorbed to soil, the urine represented the primary excretion route of 14C activity. Ileum contained the highest tissue concentration of radioactivity in all oral treatment groups. However, the skin application site contained the highest concentration of radioactivity followed by ileum after dermal exposure. Phenanthrenequinone and 9,10-phenanthrene dihydrodiol were the major urinary metabolites detected in the 0-12-h urine of all treatment groups in both routes of administration. The data suggest that the oral exposure route for phenanthrene is a greater health risk than the dermal route. However, the presence of sandy or clay soil tends to delay the elimination of phenanthrene from the plasma.

Evaluation of the use of uncertainty factors in deriving RfDs for some chlorinated compounds

Risk assessment of exposure to chemicals having a toxic endpoint routinely uses the reference dose (RfD) approach based on uncertainty factors of 10. The purpose of this investigation was to evaluate whether the magnitude of the U.S. Environmental Protection Agency (EPA) 10x uncertainty factors has scientific merit when compared with data from recent human and animal experimental studies. A compilation and comparison of ratios between LOAEL/NOAEL (lowest observed adverse effect level/no observed adverse effect level) and subchronic/chronic values was made for six chlorinated compounds, namely, carbon tetrachloride, methylene chloride, pentachlorophenol, monochlorobenzene, chlorpyrifos, and 1,1-dichloroethane. Data sets demonstrated that 91.3% of the LOAEL/NOAEL ratios were < or = 6 while 87% of the ratios for the same parameter were < or = 5. Furthermore, subchronic/chronic ratios were < or = 3.5. From our investigation we concluded that automatic safety factors of 10x are not scientifically supportable and are overly conservative for the chlorinated compounds studied here.

Pharmacokinetics of benzophenone-3 after oral exposure in male rats

Benzophenone-3 (BZ-3) is one of the UV-absorbing agents that has been used in industry and medicine for more than 30 years. Millions of consumers are exposed to benzophenones on a daily basis owing to the widespread use of these compounds in many of the products on the market, such as lipsticks, hair sprays, hair dyes, shampoo and detergent bars and sunscreen lotions. This study was performed to investigate the pharmacokinetics of BZ-3 after oral administration at 100 mg kg-1 body weight in male Sprague-Dawley rats. Absorption from the gastrointestinal tract was rapid because BZ-3 was detected in blood 5 min after administration. The peak plasma concentration (Cmax) was 25.6 +/- 4.6 micrograms ml-1 and the time of occurrence (tmax) was 3.0 +/- 0.4 h. The half-life of absorption of BZ-3 was 0.71 h. The elimination pattern was biphasic with alpha and beta half-lives of elimination of 0.88 and 15.90 h, respectively. The results of this study indicate the presence of strong binding between the plasma protein and BZ-3. Tissue distribution studies at 6 h indicate that the liver contained the highest concentration of free (58.9 +/- 23.8 micrograms) and total (free+bound or conjugated) BZ-3 (2087 +/- 60.1 micrograms), followed by kidney and testes, respectively. Urine and feces analysis indicate that urine was the major route of excretion, followed by feces. Further analysis of urine samples also indicates that conjugation of BZ-3 with glucuronic acid was the major systemic elimination route for the compound.

Salicylamide reverses the aspirin-antagonistic effect of salicylic acid on rat platelet cyclooxygenase

The antagonistic effect of salicylic acid (SA), the major metabolite of aspirin, on aspirin (ASA)-induced inhibition of cyclooxygenase has been recognized in vivo and in vitro. Salicylamide is available with aspirin in some analgesic preparations. Salicylamide shares important characteristics with salicylic acid including the lack of effect on cyclooxygenase and platelet aggregation as well as a close structural resemblance. This prompted us to study the interaction of salicylamide with aspirin and/or SA on rat platelet and cyclooxygenase. Our results showed that salicylamide has, unlike SA, no blocking effect on the anticyclooxygenase effect of aspirin in vitro. Moreover, salicylamide could dose-dependently prevent the aspirin-blocking effect of SA on platelet cyclooxygenase. These results suggest that salicylamide and SA compete for a receptor on cyclooxygenase different to that of aspirin. A functional model of cyclooxygenase enzyme is proposed.

A comparative study of the kinetics and bioavailability of pure and soil-adsorbed naphthalene in dermally exposed male rats

The aim of this study was to utilize pharmacokinetic techniques to assess the bioavailability of sandy or clay soil-adsorbed naphthalene vs chemical alone following dermal treatment of male rats. Animals were exposed to 43 micrograms total of 14C-naphthalene (pure or adsorbed to one of two soils) introduced into a shallow glass cap covering a 13-cm2 area on the skin of each rat. While both soils delayed the time to reach maximum plasma concentration of radioactivity and significantly increased the half-life of plasma absorption, only sandy soil significantly decreased the peak plasma concentration of radioactivity versus the pure compound. Within 12 h after dermal application, approximately 50% of the naphthalene dose was excreted in the urine of the pure and clay soil-adsorbed groups. However, when naphthalene was adsorbed to sandy soil, the percentages of the initial dose excreted in the urine collected between 0-12 h and 12-24 h were nearly equal (33-39%). Furthermore, sandy soil adsorption shifted the secondary excretion route from expired air to feces and significantly lowered the amount of radioactivity in expired air relative to naphthalene alone. In the presence of sandy soil, a significantly larger amount of radioactivity washed off of the skin application sites. In all groups the predominant urinary metabolites determined by high performance liquid chromatography were 2,7- and 1,2-dihydroxynaphthalenes.

Soil decreases the dermal penetration of phenol in male pig in vitro

Skin is a primary route of exposure to phenol, a major chemical found in hazardous waste sites. The effect of soil adsorption on the dermal bioavailability of phenol was assessed by applying [14C]phenol alone (P) or with sandy (P-S) or clay (P-C) soil to dermatomed male pig skin samples in flow-through diffusion cells. Maximum penetration of P-S and P-C was significantly decreased by one-half and by two-thirds, respectively, compared to P. Furthermore, the penetration of phenol into receptor fluid and the amount bound to skin were significantly lower when phenol was adsorbed to either soil versus P. While less radioactivity penetrated skin with soil-adsorbed phenol treatment than P, significantly more radioactivity was loosely adsorbed to skin and could be easily washed off of the skin surface by soap and water. Only a small fraction (< 5%) of the chemical was metabolized by skin to hydroquinone and catechol in all treatment groups. The results of this study indicate that the bioavailability and thus the potential health risk from dermal exposure to phenol is reduced if the chemical is adsorbed to soil.

Evaluation of chloroform cardiotoxicity utilizing a modified isolated rat cardiac myocytes

An improved technique for the isolation of cardiac myocytes from adult rat is described. This method produced a high yield of isolated cardiomyocytes (30-35 x 10(6) cells/heart) with viability over 88%. The rod-shaped cells represented about 70% of the viable cardiac myocytes. The leakage of creatine phosphokinase (CPK) in the incubation medium from the control was about 37% at zero time. This model was used to investigate chloroform (CHCl3) cardiotoxicity by measuring dye exclusion, change the viable cardiac myocytes shape and CPK leakage. As a result of CHCl3 exposure, there was a significant decrease in Trypan blue exclusion after 30 min and during the entire time course. The percentage of rod-shaped cells decreased significantly during the whole period of the study. Also, a significant elevation in CPK leakage after treatment with 1000 ppm CHCl3 was observed. The data show that the present technique for cardiomyocytes isolation from adult rats produced high percentage of viable cells. Furthermore, the toxic effect of CHCl3 on cardiac myocytes was time dependent.

Metabolism of benzophenone-3 in rats

Benzophenone-3 [2-hydroxy-4-methoxybenzophenone (HMB), oxybenzone, Spectra-Sorb UV-9 light absorber] is used in many cosmetics and sunscreens as a UV absorber. This study was conducted to investigate the metabolism of HMB (100 mg/kg body weight administered orally). 2,4-Dihydroxybenzophenone (DHB), 2,2'-dihydroxy-4-methoxybenzophenone (DHMB), and 2,3,4-trihydroxy-benzophenone (THB) metabolites were identified as free and conjugated forms by HPLC analysis. HMB was rapidly absorbed, metabolized, and detected in plasma (as free and protein bound) at 5 min postadministration. The parent compound and metabolites (free and conjugated) were detected at 6 hr in most tissues. DHB was present in most tissues with the highest concentration in the liver. DHMB was only detected as the conjugated form in liver, spleen, and heart. Trace amounts of THB were also detected in biological samples. Urine was the primary route, whereas feces was the secondary route of elimination of HMB and its metabolites. This study revealed O-dealkylation as the major pathway of HMB metabolism.

The mechanism of chloroform toxicity in isolated rat hepatocytes

Chloroform (CHCl3) is widely used in the manufacture of drugs, cosmetics, plastics and cleaning agents. It is also found in chlorinated drinking water. This study was designed to investigate the toxic effect of CHCl3 on isolated male rat hepatocytes using several toxicity parameters. The hepatocytes were isolated by a collagenase perfusion technique and the cell viability was determined by Trypan blue exclusion. The leakage of cytosolic enzymes such as aspartate transaminase (AST) and alanine transaminase (ALT) after treatment with CHCl3 was measured. Reduced glutathione content (GSH) and its related enzymes, glutathione reductase (GSH-Rx) and glutathione peroxidase (GSH-Px), were also evaluated to study the effect of CHCl3 on hepatocytes. Exposure to 100 and 1000 ppm CHCl3 results in a significant decrease in cell after 30 min incubation. However, the effect of 1 and 10 ppm concentrations was observed at 60 min incubation. AST leakage was significantly increased in all treatment groups, while ALT was significantly increased at 100 and 1000 ppm CHCl3 after 60 and 30 min, respectively. As early as 15 min, GSH was decreased significantly at 1000 ppm, but at 100 and 10 ppm CHCl3 the decrease in GSH began after 30 and 120 min, respectively. GSH-Px activity did not changed. However, the activity of GSH-Rx was significantly decreased at 1000 ppm CHCl3 and at the same time GSH content was decreased. The data indicate that the toxic effect of CHCl3 was dose- and time-dependent. The degree of GSH depletion correlated with increased cytotoxicity and decreased GSH-Rx activity due to CHCl3.

Influence of diltiazem and/or propranolol on rat blood glucose levels in normal and diabetic animals

Diabetes mellitus and cardiovascular disorders are both common disorders, and it could be anticipated that they coexist in many patients. Diltiazem (DZ) is widely used alone or in combination with propranolol (PROP) for the treatment of hypertension and ischemic heart disease. These drugs could interfere with carbohydrate metabolism and impair glucose tolerance. The purpose of this study was to investigate the effect of oral administration of DZ, PROP (100 and 25 mg kg-1, respectively) and their combination on fasting serum glucose and insulin levels in normal and diabetic Wistar rats. Diabetes was induced by an intraperitoneal (i.p.) injection of streptozotocin (60 mg kg-1). In normal animals, serum glucose was significantly increased after DZ, PROP and DZ/PROP treatment compared to the initial values. In diabetic rats, serum glucose was significantly increased after PROP and DZ/PROP treatments, while it was slightly increased after diltiazem treatment compared to the initial values. In normal animals, plasma cAMP is significantly decreased in all treatment groups compared to the control value, while in the plasma of diabetic rats, cAMP was significantly decreased after PROP and DZ/PROP treatments when compared to the control value. Serum potassium of normal rats decreased after the diltiazem and DZ/PROP treatments, and they tend to increase slightly after PROP treatment. Serum potassium of diabetic rats was increased significantly after PROP and DZ/PROP treatments compared to the initial values. Body weight is decreased significantly in all treatment groups in normal rats while this significant decrease was observed only after DZ/PROP treatment in diabetic rats. This investigation suggests that diltiazem alone has no worsening effects on the glycemic control in diabetic rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of D,L-verapamil, verapamil enantiomers and verapamil metabolites on the binding of vincristine to alpha 1-acid glycoprotein

Vincristine binding to solutions of alpha 1-acid glycoprotein (AGP, 2 mg/ml) and the effect of D,L-verapamil, verapamil enantiomers and the verapamil metabolites norverapamil and D617 were investigated in vitro using equilibrium dialysis and 3H-labelled vincristine. Vincristine binding to AGP (52.3 +/- 3.6%) was concentration independent over the range 0.002-2.0 micrograms/ml. The displacement of vincristine from AGP varied between 25.1 and 81.3% with D,L-verapamil and verapamil enantiomers added at concentrations in the range 5-50 micrograms/ml. In contrast, the displacement by D617 (5-100 micrograms/ml) was weaker and varied between 0 and 47%. The displacement at 20 micrograms/ml produced by D,L-verapamil, R-verapamil, S-verapamil and norverapamil was 53.1%, 56.8%, 58.9% and 53.9%, respectively, was more than double that for D617 (25%; P = 0.002). It is concluded that vincristine, D,L-verapamil and verapamil isomers and metabolites interact at binding sites on AGP. These interactions may be clinically important in multidrug resistance, for example in cancer patients with elevated levels of AGP undergoing treatment with verapamil and vinca alkaloids.