Protection against paracetamol-induced hepatic injury by prazosin pre-treatment in CD-1 mice

A synergistic depletion of glutathione has been suggested to be one critical factor in the hepatic injury in mice induced by non-toxic doses of paracetamol (APAP) when co-administered with  -adrenergic agonists. Prazosin (an  -adrenergic antagonist) could confer hepatoprotection following a toxic APAP dose (530 mg/kg) by increasing glutathione levels and enhancing bioinactivation by glucuronidation and glutathione conjugation. The effect of prazosin pre-treatment on APAP-induced gluthathione depletion and bioinactivation in vivo was assessed. Prazosin (15 mg/kg) pre-treatment provided protection against APAP-induced hepatic injury as evidenced by a significant decrease in serum transaminase (ALT) levels after 5 h (p < 0.05). Interestingly, prazosin pre-treatment did not prevent the dramatic depletion of glutathione by high dose APAP and it had no effect on the quantity of the glutathione conjugate formed. However, prazosin pre-treatment caused a significant increase in recovery of the administered dose (530 mg/kg) as the glucuronide metabolite (p < 0.05). UDP-glucuronosyltransferase (UGT) is involved in the bioinactivation of APAP by glucuronidation and we showed that prazosin had no effect on microsomal UGT kinetics. Thus, prazosin had no effect on either APAP-mediated glutathione depletion or the extent of APAP-glutathione conjugate formation and may be affecting other mechanisms to reduce oxidative stress caused by a toxic dose of APAP

Antarth, a polyherbal preparation protects against the doxorubicin-induced toxicity without compromising its antineoplastic activity

Doxorubicin (DOX), an anthracycline drug widely used for the treatment of various cancers, causes a cumulative dose-dependent cardiotoxicity that is characterized by an irreversible dilated cardiomyopathy and congestive heart failure. Antarth (ANT) a polyherbal preparation was evaluated for its cardioprotective properties against doxorubicin-induced cardiotoxicity in mice. Mice were treated with 25 mg/kg ANT orally once daily for 5 consecutive days before a single intraperitoneal injection of 15 mg/kg doxorubicin. The animals were killed 30 h after DOX treatment. DOX induced a significant elevation in the serum levels of glutamic pyruvic transaminase (GPT), glutamic oxaloacetic transaminase (GOT), creatine kinase (CK-MB) and lactate dehydrogenase (LDH), indicating its acute cardiotoxicity. The treatment of mice with ANT before DOX administration significantly reduced the serum levels of GPT, GOT, CK-MB and LDH indicating that ANT protected against the DOX-induced cardiotoxicity. Pretreatment of mice with 25 mg/kg ANT inhibited the DOX-induced decline in the antioxidant status. Intraperitoneal injection of 1.25 mg/kg DOX once daily for 9 consecutive days significantly improved the survival of mice bearing Ehrlich ascites carcinoma (EAC). Treatment of EAC with 25 mg/kg ANT alone did not affect the anticancer activity of DOX since ANT did not alter the tumor cell growth, the median survival time and average survival time of tumor bearing mice. The present study demonstrates that ANT protects mice against DOX-induced cardiotoxicity, without compromising the antineoplastic activity of DOX.

Size heterogeneity in the 3' noncoding region of South American isolates of yellow fever virus

The 3' noncoding region (3' NCR) of flaviviruses contains secondary and tertiary structures essential for virus replication. Previous studies of yellow fever virus (YFV) and dengue virus have found that modifications to the 3' NCR are sometimes associated with attenuation in vertebrate and/or mosquito hosts. The 3' NCRs of 117 isolates of South American YFV have been examined, and major deletions and/or duplications of conserved RNA structures have been identified in several wild-type isolates. Nineteen isolates (designated YF-XL isolates) from Brazil, Trinidad, and Venezuela, dating from 1973 to 2001, exhibited a 216-nucleotide (nt) duplication, yielding a tandem repeat of conserved hairpin, stem-loop, dumbbell, and pseudoknot structures. YF-XL isolates were found exclusively within one subclade of South American genotype I YFV. One Brazilian isolate exhibited, in addition to the 216-nt duplication, a deletion of a 40-nt repeated hairpin (RYF) motif (YF-XL-DeltaRYF). To investigate the biological significance of these 3' NCR rearrangements, YF-XL-DeltaRYF and YF-XL isolates, as well as other South American YFV isolates, were evaluated for three phenotypes: growth kinetics in cell culture, neuroinvasiveness in suckling mice, and ability to replicate and produce disseminated infections in Aedes aegypti mosquitoes. YF-XL-DeltaRYF and YF-XL isolates showed growth kinetics and neuroinvasive characteristics comparable to those of typical South American YFV isolates, and mosquito infectivity trials demonstrated that both types of 3' NCR variants were capable of replication and dissemination in a laboratory-adapted colony of A. aegypti.

Activation of hepatic Nrf2 in vivo by acetaminophen in CD-1 mice

The transcription factor NF-E2-related factor 2 (Nrf2) plays an essential role in the mammalian response to chemical and oxidative stress through induction of hepatic phase II detoxification enzymes and regulation of glutathione (GSH). Enhanced liver damage in Nrf2-deficient mice treated with acetaminophen suggests a critical role for Nrf2; however, direct evidence for Nrf2 activation following acetaminophen exposure was previously lacking. We show that acetaminophen can initiate nuclear translocation of Nrf2 in vivo, with maximum levels reached after 1 hour, in a dose dependent manner, at doses below those causing overt liver damage. Furthermore, Nrf2 was shown to be functionally active, as assessed by the induction of epoxide hydrolase, heme oxygenase-1, and glutamate cysteine ligase gene expression. Increased nuclear Nrf2 was found to be associated with depletion of hepatic GSH. Activation of Nrf2 is considered to involve dissociation from a cytoplasmic inhibitor, Kelch-like ECH-associated protein 1 (Keap1), through a redox-sensitive mechanism involving either GSH depletion or direct chemical interaction through Michael addition. To investigate acetaminophen-induced Nrf2 activation we compared the actions of 2 other GSH depleters, diethyl maleate (DEM) and buthionine sulphoximine (BSO), only 1 of which (DEM) can function as a Michael acceptor. For each compound, greater than 60% depletion of GSH was achieved; however, in the case of BSO, this depletion did not cause nuclear translocation of Nrf2. In conclusion, GSH depletion alone is insufficient for Nrf2 activation: a more direct interaction is required, possibly involving chemical modification of Nrf2 or Keap1, which is facilitated by the prior loss of GSH.

Leptospiral carriage by Mice and Mongooses on the island of Barbados

Leptospirosis is a zoonotic disease, maintained by chronic infection of the kidneys of reservoir animals, usually small mammals. Infection in humans is acquired from direct or indirect exposure to the urine of infected animals. Leptospirosis has a high incidence in tropical regions, and has been studied extensively in several Caribbean countries. We studied the carriage of Leptospira serovars by two small mammals which are potential maintenance host of the disease in Barbados. A total of 136 mongooses (Herpestes auropunctatus) and 97 mice (Mus musculus) were caught in live traps. Leptospiral antibodies were detected by microscopic aggutination test (MAT) using antigens representing 12 serogrouops, and kidney tissues were inoculated into polysorbate medium for isolation of leptospires. The seroprevalence (at a titre of o 100) in mice was 28.2 percent (24/85, 95 percent CI 19.0, 39.1) and in mongooses 40.7 percent (48/118, 95 percent CI 20.1, 39.0) and from 4 mongooses ( 2.9 percent, 95 percent, CI 0.8, 7.4). Mouse isolates were identified as serovars arborea (17) and bim (7). As in other parts of the world, common house mice (Mus musculus) represent a significant reservoir of leptospirosis. Although carriage of the Ballum serovar, arborea, was not unexpected, this represents the first time that an animal reservoir of serovar bim has been identified. This is significant because bim causes about 63 percent of human leptospirosis in Barbados, and control efforts and education for prevention can now be targeted at a specific reservoir. (AU)

Long-term effects of diagnostic ultrasound during fetal period on postnatal development and adult behavior of mouse

Pregnant Swiss albino mice were exposed to diagnostic levels of ultrasound (3.5 MHz, intensity 65 mW, I(SPTP) = 1 W/cm(2), I(SATA) = 240 W/cm(2)) for 10, 20 and 30 minutes on day 14 of gestation. Sham exposed controls were maintained for comparison. Fifteen pregnant mice were exposed for each group. Exposed as well as control animals were left to complete gestation and parturition. Ultrasound induced changes in maternal vaginal temperature was recorded. The changes in the physiological reflexes and postnatal mortality up to 6 weeks of age were recorded. The litters were subjected to behavioral tests for locomotor activity, learning and memory at 4 month and 1 year of age. Neither the physiological reflexes nor the postnatal mortality was affected by ultrasound exposure. However, there was a noticeable impairment in both locomotor and learning behavior even after a 10 min exposure, which further increased with increases in exposure time. Thus the present study demonstrates the neurotoxicity of diagnostic ultrasound and the high susceptibility of early fetal brain to induction of lasting detrimental changes by ultrasound exposure.

Gestational stage sensitivity to ultrasound effect on postnatal growth and development of mouse [abstract]

Pregnant Swiss albino mice were exposed to diagnostic ultrasound (3.5 MHz, 65 m W, Isptp= 1 W/cm2, 1sata=240 W/ccm2) for 30 min on any one day from day 10 to 18 gestation. A sham exposed control group was maintained for comparison. A minimum of 15 pregnant mice were exposed in each group. Exposed as well as control animals were left to complete gestation and parturition. Then offspring were observed during early postnatal development for any changes in physiological reflexes like pina detachment, eye opening, fur development, postnatal mortality, body weight, body length, head length and head width up to 6 weeks of age. Ultrasound exposure at any of the gestational age did not have any effect on the timing of onset of the physiological reflexes. But there was a significant change in the postnatal mortality, body weight, body length after exposure to ultrasound on the 14th and 16th day post coitus. Head length and head width also significantly decreased in all the exposed groups when compared to the control. The present study demonstrates that ultrasound can induce harmful effects on mouse growth and development when given at certain critical periods of gestation. (AU)

Pharmacological evaluation of some local plant extracts claimed to be used abortifacients in folklore practice

OBJECTIVE: Several local plant extracts are used in folklore practice as abortifacients. The objectives was to determine the scientific basis, if any, for these claims. METHODS: Aqeous extracts were prepared from 6 plants collected from St.Thomas, Jamaica: Leonotis nepetifolia (LN), Mentha pulegium (MP), Phyllanthus amarus (PA), Stachytarpheta jamaicensis (SJ), Gliricidia sepium (GS) and Wedelia gracilis (WG). The extracts were tested for contractile activity on isolated mouse uteri maintained in de Jalons solution. The effects of indomethacin and atropine on the contractions were used to indicate the possible mechanism of action. RESULTS: Three plant extracts (LN, MP and PA) produced dose-dependent contractions of the non-pregnant and pregnant mouse uteri. No contractions were observed with the other three extracts (SJ, GS, and WG). The contractions produced by MP were significantly reduced by indomethacin (p<0.05) but not by atropine. Contractions produced by LN and MP were blocked by either drug. Pregnant mice given LN litterd with live offspring within 24 hours. CONCLUSIONS: Of the 6 plants evaluated, 3 contracted the uterus in vitro but only one (LN) had a significant action in vivo. The contractile effect of MP may possibly be mediated via prostaglandins. However, this plant extract showed significant toxicity in vivo. (AU)

Evidence for PSP in mussels in Trinidad

Herein we present the first evidence for the presence of Paralytic Shellfish Poison (PSP) in Trinidadian waters. The toxin was found in a meat extract of the mussel, Perna viridis. PSP has not previously been demonstrated in the shellfish of Caribbean islands. The presence of PSP in Trinidad is therefore significant in that it presents an opportunity to better understand the dynamics of PSP and algal blooms in both a region and island environment not normally associated with PSP.P. viridis is not native to Trinidad, but rather originates from eastern Asia. It presented itself only recently in Trinidadian waters. Interestingly, shellfish consumption and algal blooms have had a long history of coexistence in Trinidad without any record of human intoxications. In this context, potential Public Health implications of finding PSP in a non-native shellfish species are briefly discussed.

An experimental mouse model to study the pathogenicity of Prevotella bivia and investigations of possible virulence

Induction of subcutaneous abscesses in mice was used to study the pathogenicity of Prevotella bivia both in mono-infection and in mixed cultures with Escherichia coli and Peptostreptococcus spp. Virulence factors such as coaggregation and aggregate formation of cells, haemagglutination activity and tolerance to serum bactericidal activity were investigated for their possible role in P bivia pathogenicity. Monocultures of P bivia, E coli and Peptostreptococcus spp did not induce subcutaneous abscess at concentrations as high as 10 9 colony forming units/millilitre (cfu/ml). Only E coli persisted at the infection site for up to 7 days post infection but with a marked decline in cell count (8.0x10 squaredcfu/ml). The anaerobic organisms did not persist at the infection sites beyond the fifth day. In contrast, mixed cultures of P bivia and E coli or all three organisms potentiated for infective abscess two weeks after infection. Viable cells were recovered from abscesses in greater numbers as the infection progressed. Prevotella bivia was the predominant organism in chronic abscesses while E coli predominated in abscesses in the acute stage of the infection. Prevotella bivia lacked haemagglutination activity against human and sheep erythrocytes and showed marked susceptibility to 50 percent human serum. These may limit its haematogenous spread. Its ability to form aggregates in molar salt solutions and coaggregate with facultative organisms may account for its persistence in pathological sites.(Au)

Rodent control in restaurants in the New Kingston area

Rodent infestation in New Kingston poses a serious threat to food safety and to the health of patrons who consume food prepared in restaurants there. This study sought to determine the level of rodent infestation in restaurants in New Kingston as well as the knowledge, attitudes and practices of managers and staff in relation to rodent control. A sample of 27 restaurants was selected. Inspections were carried out at each restaurants and a questionnaire was administered to managers and staff members. The results showed that 13.6 percent of the restaurants were infested with rats while 63.6 percent of the restaurants were not rodents proof. Refuse storage outside restaurants was generally unsatisfactory. Respondents from the local restaurants exhibited more in-depth knowledge about rodents than their counterparts in restaurants affiliated to overseas food chains. There was a significant association between the category of restaurant and the knowledge of respondents with respect to the difference between rats and mice. The attitude of respondents to rodent control was generally positive. The study concluded that the proliferation of rodents in New Kingston could lead to food contamination in restaurants. There is need for education of staff, improved solid waste management and more effective rodent control measures in restaurants and other premises in New Kingston.(Au)

Antidiarrhoeal effects of Ocimum gratissimum leaf extract in experimental animals

The aqueous extract of the leaves of Ocimum gratissimum was screened for antidiarrhoeal effects. The extract inhibited castor oil-induced diarrhoea in rats as judged by a decrease in the number of wet faeces in the extract-treated rats. In addition, the extract inhibited the propulsive movement of intestinal contents. On the isolated ileum of guinea-pig, the extract showed no direct action; however, it reduced the responses of the guinea-pig ileum to acetylcholine, nicotine and histamine. Phytochemical tests revealed the main constituents as tannins, steroids, triterpenoid and carbohydrates. These findings suggested that the aqueous extract of the leaves of O. gratissimum might elicit an antidiarrhoeal effect by inhibiting intestinal motility, partly via muscarinic receptor inhibition.

Topical antiinflammatory activity of phytosterols isolated from Eryngium foetidum on chronic and acute inflammation models

Eryngium foetidum L. (Apiaceae) is a Caribbean endemic plant used in folk medicine for the treatment of several antiinflammatory disorders. A preliminary phytochemical study showed that the hexane extract is rich in terpenic compounds. Chromatographic fractionation of this extract yielded: alpha-cholesterol, brassicasterol, campesterol, stigmasterol (as the main component, 95 percent) clerosterol, beta-sitosterol, delta 5-avenasterol, delta (5) 24-stigmastadienol and delta 7-avenasterol. The topical antiinflammatory activity of the hexane extract and of stigmasterol was evaluated by auricular oedema, induced by 12-0-tetradecanoylphorbol acetate (TPA), in the mouse, using single and multiple applications of the phlogistic agent. Both reduced the oedema in a similar proportion in the two model assays (acute and chronic). Meloperoxidase activity was strongly reduced by both the extract and the compound, in the acute but not the chronic model. These results indicate that the leaves of Eryngium foetidum L may be effective against topical inflammation processes. Stigmasterol also exerts a significant topical antiinflammatory activity although it cannot be considered to be a major antiinflammatory agent, therefore other bioactive components are probably involved in the activity of the hexane extract.(AU)

Monoclonal antibody mapping of the envelope glycoprotein of the dengue 2 virus, Jamaica

Although dengue (DEN) virus is the etiologic agent of dengue fever, the most prevalent vector-borne viral disease in the world, precise information on the antigenic structure of the dengue virion is limited. We have prepared a set of murine monoclonal antibodies (Mabs) specific for the envelope (E) glycoprotein of DEN 2 virus and used these antibodies in a comprehensive biological and biochemical analysis to identify 16 epitopes. Following domain nomenclature developed for the related flavivirus, tick-bourne encephalitis, three functional domains were identified. Five epitopes associated with domain A were arranged in three spatially independently regions. These A-domain epitopes were destroyed by reduction, and antibodies reactive with these epitopes were able to block virus hemagglutination, neutralize virus infectivity, and block virus haemagglutination, neutralize virus infectivity, and block virus-mediated cell membrane fusion. Domain-A epitopes were present on the full-length E glycoprotein, a 45-kDa tryptic peptide representing its first 400 amino acids (aa) and a 22-kDA tryptic peptide representing at least aa 1-120. Four epitopes mapped into domain B, as determined by their partial resistance to reduction and the localization of these epitopes on a 9-kDa tryptic or chymotryptic peptide fragment (aa 300-400). One domain-B-reactive MAb was also capable of binding to a DEN 2 synthetic peptide corresponding to aa 333-351 of the E glycoprotein, confirming the location of this domain. Domain-B epitopes elicited MAbs that were potent neutralizers of virus infectivity and blocked hemagglutination, but they did not block virus-mediated cell-membrane fusion. Domains A and B were spatially associated. As with tick-bourne encephalitis virus, determination of domain C was more problematic: however, at least four epitopes and biochemical characteristics consistent with C-domain epitopes(AU)

Improved protection against Venezuelan equine encephalitis by genetic engineering of a recombinant vaccinia virus

An improved vaccine is needed against Venezuelan equine encephalitis (VEE) virus because the existing live attenuated vaccine, TC-83, causes a high incidence of adverse effects, and the Formalin-inactivated vaccine, C-84, does not protect against airborne infection. A recombinant vaccine had previously been constructed in which the VEE structural proteins were expressed by vaccinia virus. Although protection against subcutaneous challenge with VEE was achieved, the vaccine had limited efficacy against aerosolized virus. We made a similar construct (WR100) and compared its performance as a vaccine: a synthetic promoter was inserted upstream of the VEE coding sequence to increase the amount of VEE proteins produced, and a single nucleotide in the E2 glycoprotein gene was altered to enhance immunogenicity. The WR103 virus expressed greater amounts of VEE proteins on the surface of infected cells than did WR100, and this difference was production. Sera from mice immunized with WR103 contained elevated levels of antibody to VEE, and enhanced protection against subcutaneous challenge with the pathogenic Trinidad donkey strain was achieved. This altered construct could form the basis for a better vaccine against VEE.(Au)

The age-prevalence profile of abdominal obesity among patients in a diabetes referral clinic in Jamaica

Generalised obesity is a major risk factor for cardiovascular disease, diabetes, hypertension and premature death, but abdominal or central obesity is even more closely related to these. Diabetes causes accelerated atherosclerosis and this results in peripheral vascular and ischaemic heart disease and stroke, major causes of death in diabetics in the Caribbean. Diabetics who have abdominal obesity are therefore at increased risk for these events. 485 patients attending the Diabetes Referral Clinic at the University Hospital of the West Indies, Jamaica, were evaluated for abdominal obesity based ont the ratio between their waist and hip measurements. There was an increase in the numbers of diabetics with increasing age. Abdominal obesity was significantly more prevalent among females (90 percent) than among males (34.9 percent) (X = 142; p < 0.0001), and massive obesity was detected in 31.1 percent of females. However, the prevalence of obesity among males and females was not significantly age-related. Given the high prevalence of obesity in this clinic population, more precise studies of abdominal obesity associated morbidity in diabetics should be undertaken.(AU)

Glucocorticoids and the skin

Glucocorticoids are the most effective anti-inflammatory agents currently available, but a variety of adverse effects limit their clinical usefulness. This work explores further two facets of their interaction between glucocorticoids and the skin, with the aim of identifying means of reducing glucocorticoid toxicity. (a) Metabolism of glucocorticoids by skin: Human skin is active in the terminal metabolism of corticol to cortisone, but the biological implications of this process in skin are uncertain. BEcause there are technical difficulties in dealing with human skin, an animal model, the nude mouse, has been evaluated for its suitability to the study of the metabolism of corticosterone to IIB-dehydrocorticosterone (the homologous reaction in rodents of cortisol to cortisone conversion in man); a process mediated by IIB-hydroxysteroid dehydrogenase. (b) Skin vasoconstrictor response (blanching) to topical glucocorticoids: Glucocorticoids applied topically to human skin produce vasoconstriction in dermal vessels, the degree of which correlates closely with the potency and clinically efficacy of these compounds (AU)

Cytotoxic activities of recombinant immunotoxins composed of pseudomonas toxin or diphtheria toxin toward lymphocytes from patients with adult T-cell leukemia

We have previously shown that the recombinant single-chain immunotoxin anti-Tac (Fv)-PE40, composed of the variabe domains of the anti-Tac monoclonal antibody in a single-chain form joined to a derivative of pseudomonas exotoxin (PE), is cytotoxic toward malignant cells form adult T-cell leukemia (ATL) patients. Using this assay, we have now compared the activity of anti-Tac(Fv)-PE40 with that of an improved version, anti-Tac (Fv)-PE40KDEL which contains an altered carboxyl terminus, and also with two chimeric toxins made with diphtheria toxin (DT). One of these is a fusion of amino acids 1-388 of DT with anti-Tac(Fv) and is termed DT388-anti-Tac(Fv). The other, DT388-IL2, contains interleukin 2 (IL2) at the carboxyl terminus of the same DT derivative. We incubated these toxin with malignant ATL peripheral blood mononuclear cells (PBMCs) for 1-3 days and then measured [3H]leucine incorporation. We found that anti-Tac(Fv)-PE40KDEL was the most cytotoxic agent and was followed in decreasing order of activity by anti-Tac(Fv)-PE40, DT388-anti-Tac(Fv), and finally DT388-IL2. Trypan blue staining showed that inhibition of protein synthesis correlated with cell death. Time course studies show that the recombinant toxins containing anti-Tac(Fv)-PE40DEL was 30 minutes. Normal PBMCs were resistant to all four toxins. Recombinant immunotoxins made with anti-Tac merit further study as potential reagents in the treatment of ATL.(AU)

Biological evaluation of protein quality of sorghum as affected by insect infestation

Protein quality of sorghum grains having 25, 50 and 75 percent infestation caused by mixed population of Trogoderma granarium Everts and Rhizopertha dominica Fabricius was biologically evaluated by rat growth and nitrogen balance studies. Feeding of diet containing insect infested sorghum grains (50 and 75 percent) resulted in marked decrease in food intake, protein intake, gain in body weight, food efficiency ratio, protein efficiency ratio, nitrogen consumption, nitrogen absorption, biological value, net protein utilization, dry matter digestibility, net protein retention and protein retention efficiency. These parameters showed negative association with insect infestation levels. However, 25 percent level of grain infestation did not affect these parameters significantly (AU)

Rabies reference vaccine for use as a regional standard for Latin America and the Caribbean countries

A candidate rabies reference vaccine of suckling mouse brain (SMB) origin was prepared and standardized at the Pan American Zoonoses Center (PAHO/WHO) and evaluated in a collaborative study involving seven laboratories. On the basis of three different tests, its potency, immunogenicity, and stability were demonstrated to be satisfactory. The vaccine was proposed for consideration of the Latin American and Caribbean countries as a regional standard to determine the potency of SMB vaccines, the most widely used in the region. (AU)