Influence of honey on orally and intravenously administered diltiazem kinetics in rabbits

Effect of honey on plasma concentration of diltiazem after oral and intravenous administration in rabbits, has been studied. For oral study, single dose of diltiazem (5 mg/kg, p.o.) along with saline was administered to New Zealand white rabbits (n=8). Blood samples were collected at 0, 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4, 6 and 8 hr after drug administration from marginal ear vein. After a washout period of one week, diltiazem was administered with honey (2.34 ml/kg; p.o.) and the blood samples were collected as above. To the same animals honey (2.34 ml/kg; p.o.) was continued once daily for 7 days. On 8th day, honey and diltiazem were administered simultaneously and blood samples were collected at similar time intervals as mentioned above. For intravenous study the pharmacokinetic was done in each animal on two occasions. The first study was done after single dose administration of diltiazem (5 mg/kg; i.v.) along with saline (2.34 ml/kg; p.o.). Blood samples were collected at 0, 0.083, 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4 and 6 hr after i.v. diltiazem administration. The same animals were treated with honey (2.34 ml/kg; p.o.) for seven days. On day 8, the second study was carried out with single dose i.v. administration of diltiazem along with honey (2.34 ml/kg; p.o.) and blood samples were collected. In the oral study, single dose administration of honey decreased the AUC and Cmax of diltiazem associated with significant increase in clearance and volume of distribution when compared to saline treated group. After one week administration of honey, diltiazem kinetic data showed further reduction in AUC and Cmax and increase in clearance and volume of distribution. In the i.v. study also, multiple dose administration of honey significantly reduced the AUC and increased the clearance value of diltiazem. The results suggest that honey may decrease the plasma concentration of diltiazem after its oral or i.v. administration in rabbits.     

Use of a Taqman PCR to determine the response of Mycoplasma haemofelis infection to antibiotic treatment

A quantitative Taqman polymerase chain reaction (PCR) assay was used to evaluate the response of Mycoplasma haemofelis experimentally infected cats to three antibiotic treatment regimes. Sixteen cats were intravenously inoculated with M. haemofelis from a chronically infected donor. The cats were randomly assigned to one of four treatment groups each containing four cats: oral doxycycline at 10 mg/kg/day for 14 days, oral enrofloxacin at 5 mg/kg/day for 14 days, oral enrofloxacin at 10 mg/kg/day for 14 days, and an untreated control group. DNA, extracted from blood samples collected on days 0, 7, 14, 21, 25, 28, 32, 35, 42 and 54 post-inoculation (PI), was subjected to quantitative Taqman PCR. The M. haemofelis copy number was significantly lower in the doxycycline group (P=0.008), the 5 mg/kg/day enrofloxacin group (P=0.006) and the 10 mg/kg/day enrofloxacin group (P=0.005) compared to the untreated control group. No significant differences were found between any of the three antibiotic treated treatment groups. All three antibiotic treatment regimes evaluated in this study were effective at reducing M. haemofelis copy number.     

The mechanism of hypoglycemic action of the semi-purified fractions of Averrhoa bilimbi in streptozotocin-diabetic rats.

In the present study, we have examined the possible mechanism of the hypoglycemic action of the semi-purified fractions of an ethanolic extract of Averrhoa bilimbi Linn (Oxalidaceae) leaves (ABe) in streptozotocin-diabetic male Sprague-Dawley (SD) rats. The ABe was partitioned with water and butanol to yield a butanol-soluble fraction (BuF) and a water-soluble fraction (AF). The AF was further partitioned with ethyl acetate and hexane to obtain ethyl acetate (EF) and hexane (HF) soluble fractions. The hypoglycemic property of each fraction was assessed by the oral glucose tolerance test (OGTT) at a dose of 125-mg/kg-body weight in streptozotocin (STZ)-diabetic rats (STZ 60 mg/kg i.p.). Fractions AF, BuF and the reference drug metformin (500 mg/kg body weight), produced significant blood glucose-lowering effect in the diabetic rats when compared to the vehicle (distilled water). In the long-term study, the diabetic rats were randomly divided into 4 groups and treated orally by gavage with vehicle, AF (125 mg/kg body weight), BuF (125 mg/kg body weight), and metformin (500 mg/kg body weight) respectively twice a day for 14 days. On day 7 and day 14, AF and BuF, like the reference drug, metformin, lowered the fasting blood glucose concentration significantly (P < 0.05) when compared with the vehicle. The serum insulin level was significantly increased in the AF-treated rats only on day 14 when compared to that in the vehicle-treated rats on day zero (P < 0.05). The serum insulin level in BuF-treated rats was also significantly higher (P < 0.05) on both day 7 and day 14 compared to that on day zero. Hepatic glucose-6-phosphatase activity was significantly lower (P<0.05) in AF- and metformin-treated groups, but not in BuF-treated groups, compared to that in vehicle-treated group. However, there was no change in hepatic glycogen content in AF-, BuF- and metformin-treated group compared to the vehicle-treated group. These results indicate that AF is more potent than BuF in the amelioration of hyperglycemia in STZ-diabetic rats and is a potential source for the isolation of new orally active agent(s) for anti-diabetic therapy.     

Gene expression profiling reveals multiple toxicity endpoints induced by hepatotoxicants

Microarray technology continues to gain increased acceptance in the drug development process, particularly at the stage of toxicology and safety assessment. In the current study, microarrays were used to investigate gene expression changes associated with hepatotoxicity, the most commonly reported clinical liability with pharmaceutical agents. Acetaminophen, methotrexate, methapyrilene, furan and phenytoin were used as benchmark compounds capable of inducing specific but different types of hepatotoxicity. The goal of the work was to define gene expression profiles capable of distinguishing the different subtypes of hepatotoxicity. Sprague-Dawley rats were orally dosed with acetaminophen (single dose, 4500 mg/kg for 6, 24 and 72 h), methotrexate (1mg/kg per day for 1, 7 and 14 days), methapyrilene (100mg/kg per day for 3 and 7 days), furan (40 mg/kg per day for 1, 3, 7 and 14 days) or phenytoin (300 mg/kg per day for 14 days). Hepatic gene expression was assessed using toxicology-specific gene arrays containing 684 target genes or expressed sequence tags (ESTs). Principal component analysis (PCA) of gene expression data was able to provide a clear distinction of each compound, suggesting that gene expression data can be used to discern different hepatotoxic agents and toxicity endpoints. Gene expression data were applied to the multiplicity-adjusted permutation test and significantly changed genes were categorized and correlated to hepatotoxic endpoints. Repression of enzymes involved in lipid oxidation (acyl-CoA dehydrogenase, medium chain, enoyl CoA hydratase, very long-chain acyl-CoA synthetase) were associated with microvesicular lipidosis. Likewise, subsets of genes associated with hepatotocellular necrosis, inflammation, hepatitis, bile duct hyperplasia and fibrosis have been identified. The current study illustrates that expression profiling can be used to: (1) distinguish different hepatotoxic endpoints; (2) predict the development of toxic endpoints; and (3) develop hypotheses regarding mechanisms of toxicity.     

High incidence of a concentration-dependent skin reaction in children treated with phenytoin.

A particularly high incidence of rash was seen in children with epilepsy treated with phenytoin. Ten children with untreated epilepsy were therefore included in a prospective study and given either 3 (group 1) or 6 (group 2) mg of phenytoin/kg body weight/day for five days followed by 6 mg/kg body weight/day for both groups. Four of the five children in group 2 compared with only one of the five in group 1 developed a rash seven to 12 days after the start of treatment. Patients with rashes had significantly higher plasma phenytoin concentrations. Whenever the phenytoin concentration was higher than 14 micromol/l on day 5 a rash occurred. These findings indicate that the generalised skin reaction is caused by a high body burden of phenytoin, which results from either a high load of the drug or a low clearance rate.     

Influence of acidic beverage (Coca-Cola) on pharmacokinetics of ibuprofen in healthy rabbits

The study was aimed at determining the effect of Coca-Cola on the pharmacokinetics of ibuprofen in rabbits. In a cross-over study, ibuprofen was given orally in a dose of 56 mg/kg, prepared as 0.5% suspension in carboxymethyl cellulose (CMC) and blood samples (1 ml) were drawn at different time intervals from 0-12 hr. After a washout period of 7 days, Coca-Cola in a dose of (5 ml/kg) was administered along with ibuprofen (56 mg/kg) and blood samples were drawn from 0-12 hr. To these rabbits, 5 ml/kg Coca-Cola was administered once daily for another 7 days. On 8th day, Coca-Cola (5 ml/kg) along with ibuprofen (56 mg/kg), prepared as a suspension was administered and blood samples (1 ml each) were drawn at similar time intervals. Plasma was separated and assayed for ibuprofen by HPLC technique and various pharmacokinetic parameters were calculated. The Cmax and AUC0-alpha of ibuprofen were significantly increased after single and multiple doses of Coca-Cola, thereby indicating increased extent of absorption of ibuprofen. The results warrant the reduction of ibuprofen daily dosage, frequency when administered with Coca-Cola.     

Histopathological and hemodynamic studies supporting hypoxia and vascular disruption as explanation to phenytoin teratogenicity.

The limb plates and craniofacial regions in rabbit fetuses were examined shortly after the last dose of phenytoin on day 16 after daily administration by gavage with either 150 mg/kg on days 14-16 or 300 mg/kg on days 15-16. Both treatment regimens resulted in similar changes. Histologically, the digital areas of the limb plates showed extensive edema and dilated blood vessels within 2 h. After 8 h, vascular disruption occurred with hemorrhages. At 24-48 h after dosing, mesenchymal necrosis and, on some occasions, amputation of digits was observed. In the craniofacial region, well-defined superficial hemorrhage was seen in the frontal and nasal region at 8 h. Histologically, subectodermal hemorrhage caused by vascular disruption and microfocal mesenchymal necrosis was observed. At 48 h, some fetuses showed severe diffuse intracranial and superficial hemorrhage, resulting in massive tissue damage, also in the central nervous system (CNS). Maternal heart rate, blood pressure, PO2, and PCO2 were also measured in awake pregnant rabbits 6 h after the last dose on day 16 after daily administration with 150 mg/kg during gestational days 14-16. An attempt was also made to measure fetal heart rate in anesthetized rabbits. The maternal heart rate and blood pressure decreased with about 15% in phenytoin-treated animals, resulting in a decrease in PO2 (approximately 15%) and an increase in PCO2 (approximately 15%). A decrease in fetal heart rate was also registered. The results thus indicate that phenytoin exerts its teratogenic effects by inducing fetal hypoxia, leading to vascular disrupture and necrosis of existing and developing structures.     

Identical phalangeal defects induced by phenytoin and nifedipine suggest fetal hypoxia and vascular disruption behind phenytoin teratogenicity.

In previous experimental studies in rabbits, we have shown that vasodilating drugs (including nifedipine) cause distal digital defects. These defects were preceded by edema, hemorrhage, and finally necrosis of the developed cartilage in the phalanges. The underlying mechanism is most likely a fetal hypoxic response, secondary to maternal hypotension and decreased uteroplacental blood flow. Since phenytoin is known to cause distal digital defects both in man and rabbits, we decided to compare the defects provoked by oral administration of phenytoin (100 mg/kg) versus nifedipine (8.3 mg/kg) to New Zealand White rabbits on days 6-18 of gestation. In order to investigate phase-specificity, phenytoin (150 mg/kg) was given on days 14-17. The result of single dose administration on day 16 of phenytoin (300 mg/kg) versus nifedipine (33.2 mg/kg) was also studied. In this latter experiment maternal heart rate was measured up to 21 hours after phenytoin administration. Phenytoin induced digital defects identical with those produced by nifedipine and caused marked maternal cardiodepression. The defects consisted of a reduction, absence, or abnormal structure of the distal phalanges. The distal phalanx of the fourth digit on the hindpaw was the first to be affected, with inclusion of other phalanges, both on the hind- and forepaws, with increasing dose. The sensitive period for induction and histological appearance of these defects was identical for phenytoin and nifedipine. These results suggest that vascular disruption due to a fetal hypoxic response lies behind phenytoin teratogenicity, as has been shown for vasodilators. A cardiodepressive action on the maternal and fetal hearts, possibly in combination with decreased uteroplacental blood flow, is discussed as a probable factor behind phenytoin teratogenicity.     

Co-administration of dextromethorphan during pregnancy and throughout lactation significantly decreases the adverse effects associated with chronic morphine administration in rat offspring.

In this study, we have focused our investigation of the facts whether co-administration of a NMDA antagonist dextromethorphan (DM) with morphine during pregnancy and throughout lactation could prevent the adverse effects associated with chronic morphine administration in rat offspring. Adult female Sprague-Dawley rats were randomly separated into four groups and were received subcutaneous injection of either saline, morphine, morphine + dextromethorphan or dextromethorphan twice a day and progressively increased 1 mg/kg at 7-day intervals from a beginning dose of 2 mg/kg for both morphine and dextromethorphan. The rats were mated between days 7 and 8. Administration of drugs was continued during pregnancy. After rat offspring were born, the doses of morphine or dextromethorphan injected into the maternal rats were increased by 1 mg/kg every two weeks till the offspring were 30 day old. The results showed that mortality of morphine group is much higher than control group. The offspring of morphine group weighed significantly less than control group on postnatal day 14 (p14), p30 or p60. The antinociceptive effect of morphine on p14 rats was reduced in the morphine group and indicated the development of morphine tolerance. The hippocampal NMDA receptor densities have been shown decreased on p14 rats. The precipitated withdrawal symptoms were assessed on p7 rats. Rats in morphine group showed greater frequency of abdominal stretch and wet dog shake in 2 hr than control group. On the other hand, co-administration of DM with morphine effectively prevented all these adverse effects of morphine to the offspring rats. DM co-administered with morphine also partially prevented the development of morphine tolerance in maternal rats. If this effect of dextromethorphan is applied to clinical pregnant patients with morphine addiction or chronic pain, it will have a great value for the benefit of their children.     

一种高尿酸血症大鼠模型诱导方法的改良和效果评价研究

目的: 探索短期内诱导高尿酸血症大鼠模型的有效方法,并对模型效果进行评价。方法: 雄性SD大鼠随机分为对照组(CT组,6只)和5个模型组(M1-M5组),每组8只;M1组(每天酵母膏10 g/kg+腺嘌呤100 mg/kg 2次灌胃,于模型诱导的第7日1次性腹腔注射氧嗪酸钾300 mg/kg)、M2组(每天酵母膏10 g/kg+腺嘌呤100 mg/kg灌胃2次,于模型诱导第1、3、7日每天腹腔注射1次氧嗪酸钾300 mg/kg)、M3组(每天酵母膏10 g/kg+腺嘌呤100 mg/kg灌胃 2次,每天腹腔注射1次氧嗪酸钾300 mg/kg)、M4组(每天酵母膏20 g/kg+腺嘌呤100 mg/kg灌胃 2次,每天腹腔注射1次氧嗪酸钾300 mg/kg)、M5组(每天酵母膏30 g/kg+腺嘌呤100 mg/kg灌胃2次,每天腹腔注射1次氧嗪酸钾300 mg/kg)、CT组(5个模型组按相同的时间、体重计算等体积灌胃和腹腔注射生理盐水),造模7 d;分别在造模结束时和2周后采集24 h尿样和血样检测尿酸、肌酐水平,取肾脏和胃称重,观察肾脏病理变化。结果: 与CT组相比,造模结束后,所有模型组大鼠体重均显著降低(P＜0.01);除M2组外,其他造模组大鼠均有亡,M4组和M5组因死亡率高未做后续分析,M1和M3组分别死亡4例和2例;造模结束后,模型大鼠血尿酸、尿尿酸水平明显升高(P＜0.01),并且M2组的血尿酸水平显著高于其他各组(P＜0.05);继续喂养2周后,各模型组的血尿酸和尿尿酸水平仍显著升高(P＜0.05);各模型组大鼠肾脏重量也明显增加(P＜0.01);病理检查显示,模型组大鼠肾脏出现明显炎症反应和结构破坏。结论: 采用酵母膏(10 g/kg)、腺嘌呤(100 mg/kg)联合氧嗪酸钾(300 mg/kg)间隔(第1、3、7日)注射的方案可在短期内安全地诱导高尿酸血症大鼠模型,模型效果持续时间较长,适合在相关研究中应用。     

Effects of dietary conjugated linoleic acid supplementation on performance and immune function of weaned pigs

Two experiments were conducted to evaluate the effect of dietary conjugated linoleic acid (CLA) on performance and immune responses of weaned pigs. In Exp. I, 72 crossbred pigs weaned at 19 to 23 days of age and weighing 7.20 +/- 0.11 kg were randomly allotted to four diets supplemented with CLA at 0, 1, 2 or 3%. On day 14, pigs were injected with ovalbumin (1mg per kg BW) and blood samples were collected on day 7 and 14 after injection to test the specific OVA antibody. In Exp. II, 36 crossbred pigs weaned at 26 to 30 days of age and weighing 8.12 +/- 0.14 kg were randomly divided into two diets containing either 0 or 2% CLA. On day 14 and 28, blood samples were obtained to determine the lymphocyte proliferation and PGE2 levels in both trials, and CD4+, CD8+ T cells subsets and interleukin-1beta production were tested in Exp. II. In Exp. I both average daily gain and average daily feed intake of weaned pigs were improved quadratically and feed efficiency was increased linearly by CLA supplementation. Lymphocyte proliferation response to concanavalin A was increased quadratically as dietary CLA concentration increased on day 14 and 28. Ovalbumin antibody production levels were increased linearly on day 7 after injection of ovalbumin and increased quadratically on day 14 after injection, which follows the increased CLA levels, whereas CLA reduced linearly the production of prostaglandin E2 (PGE2). The results of Exp. II indicated that CLA improved performance, lymphocyte proliferation, and increased the CD8+ lymphocyte population, while reduced the production of PGE2 and interleukin-lbeta (IL- 1beta). These results suggest that the supplementation of CLA enhanced lymphocyte proliferation function, possibly by regulating the PGE2 production, and improved growth performance of pigs. Further studies are needed to determine the mechanism of CLA-induced inhibition of IL-1beta production.     

Decreased Benzodiazepine Receptor Density in Rat Cerebellum Following Neurotoxic Doses of Phenytoin

Abstract: The effect of acute and chronic administration of phenytoin on [³H]-flunitrazepam binding was examined in the rat cerebellum. There was no significant effect of phenytoin on [³H]flunitrazepam binding in the rat cerebellum 1 and 6 h after a single i.p. injection of 200 mg/kg of phenytoin. However, after 14 days and 28 days of chronic phenytoin administration, significant de-creases in [³H]flunitrazepam receptor density were observed, with no changes in apparent affinity constants in the rat cerebellum. This effect of phenytoin was dose-dependent, as lower doses of phenytoin (100 mg/kg/day) for 14 or 28 days produced no alterations in [³H]flunitrazepam binding in the rat cerebellum. Light-microscopic examination of the rat cerebellum treated with 200 mg/kg/day of phenytoin for 14 days showed degeneration of the Purkinje cells, with edematous Bergmann astrocytes. These data provide evidence for the neuronal localization of benzodiazepine receptors on cerebellar Purkinje cells.     

Protection to glycolysis by a combination of 5-hydroxy-L-tryptophan and 2-aminoethylisothiuronium bromide hydrobromide in lethally irradiated rats.

Rate of glycolysis in vivo at different time intervals following 8 Gy [LD100(30)] whole body gamma radiation (WBGR) was evaluated by estimating liver glycogen, blood sugar, serum lactic dehydrogenase (LDH) and blood lactic acid concentration in adult male Sprague Dawley rats. Within 1 hr of radiation exposure, a significant fall in liver glycogen was observed in rats fed food and water ad libitum. The glycogen content increased after 24 hr and had returned to control level on 7th day after radiation exposure. Blood sugar, serum LDH and blood lactate levels increased significantly as compared to non irradiated controls. Pretreatment with 5-hydroxy-L-tryptophan (5-HTP; 100 mg/kg) + 2-aminoethylisothiuronium bromide hydrobromide (AET; 20 mg/kg) ip 30 min before 8 Gy WBGR, modified these values and restored them to normal level on 7th day post-irradiation.     

Enhanced erythrocytic lipid peroxides level in rabbits after repeated parental administration of iron

An experiment was conducted in rabbits to evaluate the possible involvement of oxidative stress in iron-overload animals. Ten adult female New Zealand white rabbits were divided into 2 equal groups with 5 animals each. Group II animals received intramuscular iron dextran injections (120 mg/kg body wt/day) on alternate day for 14 days (8 injections), while Group I animals did not receive any iron supplementation to serve as negative controls. The blood samples were collected by cardiac puncture before the start of iron dosing and thereafter, at weekly intervals for 28 days. The samples were processed to measure blood iron concentration, packed cell volume, erythrocytic lipid peroxide (LPO) level, superoxide dismutase (SOD) and catalase (CAT) activities. The blood iron concentration showed a rising trend following repeated iron administration, and the mean level recorded on day 14 was significantly higher than respective day 0 value. LPO level remained significantly higher from day 14 onwards till the end of the observation period of 14 more days after cessation of iron adminstration. Erythrocytic superoxide dismutase activities showed a transient significant rise on day 7, and thereafter, showed a declining trend, but remained statistically comparable to respective day 0 or corresponding value of the control animals.     

Two generation reproduction study of ethylbenzene by inhalation in Crl-CD rats

BACKGROUND: This study was conducted to evaluate the potential adverse effects of ethylbenzene (EB) on reproductive capability from whole-body inhalation exposure of F0 and F1 parental animals. METHODS: Four groups of Crl:CD(SD)IGS BR rats (30/sex/group for F0 and 25/sex/group for F1) were exposed to 0, 25, 100, and 500 ppm EB for 6 hr/day for at least 70 consecutive days before mating. Inhalation exposure for the F0 and F1 females continued throughout mating, gestation through gestation day (GD) 20, and lactation days (LD) 5-21. On LD 1-4, females received EB in corn oil via oral gavage at dose levels of 26, 90, and 342 mg/kg/day (divided into three equal doses, approximately 2 hr apart), as calculated from a physiologically-based pharmacokinetic (PBPK) model to provide similar maternal blood area-under-concentration (AUC) as provided by inhalation. Pups were weaned on postnatal day (PND) 21 and exposure of the F1 generation started on PND 22. Estimates of internal exposure were determined by measuring EB concentrations in blood collected from F1 dams (4/group) and their culled pups 1 hr after the last gavage dose on PND 4. On PND 22, blood was collected from these same F1 dams and their weanlings for EB analysis 1 hr after a 6-hr inhalation exposure. The remainder of the F2 generation was not directly exposed. RESULTS: EB exposure did not affect survival or clinical observations. Male rats in the 500 ppm group in both generations gained weight more slowly than the controls. There were no indications of adverse effects on reproductive performance in either generation. Male and female mating and fertility indices, pre-coital intervals, spermatogenic endpoints, ovarian follicle counts, reproductive organ weights, lengths of estrous cycle and gestation, live litter size, pup weights, developmental landmarks, and postnatal survival were unaffected. No adverse exposure-related macroscopic pathology was noted at any level. CONCLUSIONS: Increased liver weights were found in the animals exposed to 500 ppm. F1 maternal whole blood EB concentrations of 0.49, 3.51, or 18.28 mg/L were found 1 hr after administration of a composite oral dose of 26, 90, or 342 mg/kg/day, respectively, but no detectable EB was found in blood samples of their F2 PND 4 culled pups. F1 maternal mean whole blood EB levels 1 hr after a 6-hr inhalation exposure on postpartum day (PPD) 22 was 0.11 mg/L (25 ppm), 0.56 mg/L (100 ppm), and 11 mg/L (500 ppm). For the offspring exposed with their dams on PND 22, F2 pup blood EB concentrations ranged from 0.017-0.039 mg/L (25 ppm), 0.165-0.465 mg/L (100 ppm), and 8.82-15.74 mg/L (500 ppm). Because decreased weight gain in the 500 ppm males was transient and no histopathological changes were associated with the increased liver weights in the 500 ppm male and female groups, these changes were not considered adverse. Therefore, for parental systemic toxicity, 100 ppm was considered a NOEL and 500 ppm a NOAEL in this study. The 500 ppm exposure concentration was considered a NOAEL for F0 and F1 reproductive toxicity and offspring developmental endpoints.     

Morphological changes in the endocrine pancreas of mice after treatment with streptozotocin combined with cyclophosphamide and neurotropin.

The effect of neurotropin (NSP) in combination with streptozotocin (STZ) and cyclophosphamide (CY) on blood glucose and pancreatic histopathology on day 7 and day 14 after the initiation of the treatment was studied in C57Bl/6 male mice. STZ (40 mg/kg) and NSP (1 mg/kg) were applied intraperitoneally on five consecutive days and CY (150 mg/kg)--twice on day 1 and day 3. In single B cells dilatation of the endoplasmic reticulum was found. On day 7 in proximity to some endocrine cells in the mice treated with STZ, STZ + CY + NSP and STZ + CY macrophages were observed. On day 14 lymphocytic infiltration of the islets was demonstrated only in the groups of mice injected with STZ, STZ + CY while in the group treated with the combination STZ + CY + NSP no infiltration was seen. All experimental groups showed no biochemical evidence for hyperglycemia probably due to the mild destruction of a small number of B cells. The results indicate that NSP might possess a restorative action on insulitis induced by multiple low dose streptozotocin administration in mice.     

The effect of gabapentin and phenytoin on sperm-morphology in Wistar rats

The objective of the present study was to investigate the effects of the antiepileptic drugs, gabapentin and phenytoin, on sperm morphology in Wistar rats. Groups (n=5) of rats were treated with cyclophosphamide (20 mg/day), gabapentin (16, 25, 32 mg/day) and phenytoin (3.5, 5.5, 7 mg/day) for five consecutive days. 14 and 35 days after the last exposure, sperm morphology was evaluated by standard procedure. Gabapentin and phenytoin did not induce significant changes in sperm morphology. The results suggest that phenytoin and gabapentin are not germ cell mutagens in males, and do not appear to adversely affect male fertility.     

Management of malaria in Thailand

The purpose of treatment for uncomplicated malaria is to produce a radical cure using the combination of: artesunate (4 mg/kg/day) plus mefloquine (8 mg/kg day) for 3 days: a fixed dose of artemether and lumefantrine (20/120 mg tablet) named Coartem (4 tablets twice a day for three days for adults weighing more than 35 kg): quinine 10 mg/kg 8-hourly plus tetracycline 250 mg 6-hourly for 7 days (or doxycycline 200 mg as an alternative to tetracycline once a day for 7 days) in patients aged 8 years and over: Malarone (in adult 4 tablets daily for 3 days). In treating severe malaria, early diagnosis and treatment with a potent antimalarial drug is recommended to save the patient's life. The antimalarial drugs of choice are: intravenous quinine or a parenteral form of an artemisinin derivative (artesunate i.v./i.m. for 2.4 mg/kg followed by 1.2 mg/kg injection at 12 and 24 hr and then daily for 5 dayss; artemether i.m. 3.2 mg/kg injection followed by 1.6 mg/kg at 12 and 24 hrs and then daily for 5 days; artemether i.m. (Artemotil) with the same dose of artemether or artesunate suppository (5 mg/kg) given rectally 12 hourly for 3 days. Oral artemisinin derivatives (artesunate, artemether, and dihydroartemisinin with 4 mg/kg/day) could replace parenteral forms when patients can tolerate oral medication. Oral mefloquine (25 mg/kg divided into two doses 8 hrs apart) should be given at the end of the artemisinin treatment course to reduce recrudescence.     

Stereoselective disposition of hydroxychloroquine and its metabolites in rats

Racemic hydroxychloroquine-sulfate (HCQ-sulfate) was administered to rats orally. Groups of 9 male and 9 female rats received doses of 0, 8, 16, or 24 mg/kg/day for 6 weeks, followed by a reduction of the higher doses to 8 mg/kg/day for the duration of the study. Whole blood samples were collected at 0, 3, 6, 8, and 10 weeks, and eleven tissues were harvested after the tenth week. The concentrations and enantiomer ratios of the parent drug and three metabolites, desethylhydroxychloroquine (DHCQ), desethylchloroquine (DCQ), and bisdesethylchloroquine (BDCQ), were determined. The highest concentration of HCQ was found in the intestinal smooth muscle, and the lowest in the brain and adipose tissue. The highest concentrations of the metabolites were found in the liver, adrenals, and lung tissue. The metabolism of HCQ in the rats was found to be stereoselective with R/S > 1 for the drug and < 1 for the metabolites. Gender-specific differences in the proportions of the drug and its metabolites and their enantiomers in blood and tissue were found. Varying dosages appeared to have only a temporary influence on blood concentrations and not to effect the enantiomer ratios in blood. Only a limited number of tissues exhibited significant differences between dose groups. There were no observed differences in enantiomer ratios among the blood collection times. © 1995 Wiley-Liss, Inc.     

A comparative study of the inhibition of hepatic aldehyde dehydrogenases in the rat by methyltetrazolethiol, calcium carbimide, and disulfiram

Methyltetrazolethiol (1-methyl-5-mercapto-1,2,3,4-tetrazole, MTT) is a heterocyclic substituent of the cephalosporin antibiotics, cefamandole, cefoperazone, and moxalactam. Pretreatment of rats with MTT has been reported to increase blood acetaldehyde concentration after ethanol administration. The time course of MTT-induced inhibition of hepatic aldehyde dehydrogenases (ALDH) was determined in adult, male Sprague-Dawley rats in comparison with the hepatic ALDH inhibition induced by calcium carbimide (calcium cyanamide, CC) and disulfiram (D). The apparent onset of maximal inhibition of hepatic low Km ALDH occurred at 2 h for 50 mg/kg MTT (subcutaneous, s.c.) and 7 mg/kg CC (oral) and at 24 h for 300 mg/kg D (oral). The relative magnitude of maximal inhibition of low Km ALDH was CC greater than D greater than MTT. The relative duration of enzyme inhibition was D greater than MTT greater than CC. High Km ALDH was only inhibited by CC. Hepatic low Km ALDH was selectively inhibited by s.c. and oral administration of 125 mg/kg MTT. For s.c. administration of 125 mg/kg MTT, the magnitude of maximal enzyme inhibition and the duration of inhibition were greater than for the 50 mg/kg dose. Oral administration of 125 mg/kg MTT produced similar inhibition of hepatic low Km ALDH compared with s.c. administration of the same dose. The time course of blood ethanol and acetaldehyde concentrations was determined for the intravenous infusion of two 0.3-g/kg doses of ethanol to rats that were pretreated orally with saline (1 h), MTT (125 mg/kg, 2 h), or CC (7 mg/kg, 1 h). The relative increase in blood acetaldehyde concentration compared with saline pretreatment was CC greater than MTT. The elimination of ethanol from blood was slower in the MTT- and CC-pretreated animals, and this effect was more pronounced for CC pretreatment. Overall, the data demonstrate that the characteristics of hepatic ALDH inhibition for MTT are different from those of the known ALDH inhibitors, CC and D.