Prevalence of Ehrlichia ruminantium in adult Amblyomma variegatum collected from cattle in Cameroon

Ehrlichia ruminantium, the etiologic agent of the economically important disease heartwater, is an obligate intracellular bacterium transmitted by ticks of the genus Amblyomma, particularly A. hebraeum and A. variegatum. Although serologic and microscopic evidence of the presence of heartwater have been reported in ruminants in Cameroon, knowledge of E. ruminantium infection in the tick vector, A. variegatum, is lacking. In order to determine the infectivity of A. variegatum ticks by E. ruminantium, we analysed 500 un-engorged A. variegatum ticks collected by hand-picking from predilection sites from 182 cattle [115 ticks from 82 cattle at Société de Développement et d’Exploitation des Productions Animales (SODEPA) Dumbo ranch (SDR) and 385 ticks from 100 cattle at the Upper Farms ranch (UFR)] by amplification of the open reading frame (ORF) 2 of the pCS20 region of E. ruminantium. PCR amplification of the 279 bp fragment of the pCS20 region detected E. ruminantium DNA in 142 (28.4 %) of the 500 ticks with a higher infection rate (47/115; 40.9 %) observed in ticks from SDR and 24.7 % (95/385) of ticks collected from cattle at UFR. Twenty five randomly selected PCR products were sequenced and results indicated that some of the isolates shared homology with one another and to sequences of E. ruminantium in the GenBank. This report represents the first molecular evidence of E. ruminantium infection in A. variegatum ticks in Cameroon and suggests possible exposure of cattle to this pathogen in our environment.     

Gene disruption of caspase-3 prevents MPTP-induced Parkinson's disease in mice

The development of Parkinson’s disease is accompanied by concurrent activation of caspase-3 and apoptosis of dopaminergic neurons of human patients and rodent models. The role of caspase-3, a final executioner of apoptosis, in the pathogenesis of Parkinson’s disease, however, remains to be determined. Here, we show that gene disruption of caspase-3 protects mice from 1-methyle-4-phenyl-1,2,3,6-tetrahmydropyridine (MPTP)-induced Parkinsonian syndrome, as reflected by reversal of MPTP-induced bradykinesia and decreased tyrosine hydroxylase expression in the nigra-striatum. MPTP treatment resulted in increased caspase-3 activation and apoptosis in the substantia nigra of wild-type mice at 24 h after the inception of MPTP treatment, as compared with vehicle-treated control animals. Gene disruption of caspase-3 prevented MPTP-induced apoptosis in the substantia nigra. At 7 days after MPTP treatment, tyrosine hydroxylase expression was suppressed and infiltration of activated microglia and astrocytes was markedly increased in the nigra-striatum of wild-type mice. All of these alterations following MPTP treatment were blocked by disruption of caspase-3 in mice. These results clearly indicate that caspase-3 activation is required for the development of MPTP-induced Parkinson’s disease in mice. These findings suggest that activation of caspase-3-mediated apoptosis of dopaminergic neurons in the early stage may play an important role in the pathogenesis of Parkinson’s disease.     

Genotoxicity studies on the azo dye Direct Red 2 using the in vivo mouse bone marrow micronucleus test.

The clastogenicity of the azo dye Direct Red 2 (DR2) has been investigated using the murine bone marrow micronucleus assay. A potent dose-dependent response was observed following oral gavage of DR2 up to 4 mg/kg, after which significant toxicity to the erythroid compartment was observed. The route of administration had a significant effect on the frequency of micronucleus formation: intraperitoneal injection was approximately two-fold less clastogenic than the equivalent dose delivered orally (p<0.05). The requirement for activation of DR2 by intestinal microflora was indicated by the fact that mice given acid-treated water prior to administration of DR2 showed a significant reduction (40%; p<0.001) in micronucleated polychromatic erythrocyte formation. The implications of these findings for the health and safety of occupationally exposed workers are discussed.     

Census of mental hospital patients and life expectancy of those unlikely to be discharged.

A census in a London mental hospital was performed so that the numbers of patients requiring permanent care for the next 20 to 40 years could be estimated. Of 1467 resident patients 20% had been admitted in the preceding five months and 15% in the year before that. Of the 65% who had been in hospital for over 17 months 1% (16 patients) had been in hospital for over 5o years. Altogether 257 (18%) patients would probably be discharged, 339 (23%) might possibly be discharged if there were adequate community facilities, but 871 (59%) were not likely to be discharged; 239 patients under the age of 65 who had been admitted between 1950 and 1973 were unlikely to be discharged. There were about 10 new younger long-stay patients from each year''s admissions. Three conditions--schizophrenia, organic brain syndrome, and affective illness--affected 79% of the population. Fourteen per cent had been employed on admission and 28% were considered employable or possibly employable. Half of those who might be considered for discharge (296) would need a hostel. No rehabilitation was needed or possible for 40% of the patients; 299 (20%) patients were chairbound or bedridden and 400 (27%) were totally dependent on nursing and 587 (40%) partly dependent. Twenty months after the census 361 (25%) patients had left (59 had been readmitted), 284 (19%) had died, and 822 (56%) had remained as inpatients. The most realistic future prediction was that 210 (14%) of these patients would still be in the hospital in 20 years and 43 (3%) in 40 years. In the light of these findings and the scarceness of resources current Department of Health and Social Security plans for phasing out mental hospitals must be challenged.     

Comparative depressive actions of barbiturates on potassium chloride uptake by intact barley and rice seedlings

Summary

The comparative depressive actions of the three barbiturates, barbital, amobarbital, and secobarbital, respectively classed as long-, medium-, and short-acting barbiturates, on potassium and chloride ion uptake by intact barley and rice seedlings were investigated. Barbital exerted the least and secobarbital the most depressive action on the uptake of both potassium and chloride ions by both types of seedlings. The functioning of the Meyer-Overton principle regarding lipid solubility in relation to drug or anaesthetic potency, observed previously in germinating angiosperm seedlings and in germinating pollen grains, was also evident in this investigation.     

Population growth of Rhopalosiphum padi under different thermal regimes: an agent-based model approach

1. Rhopalosiphum padi (Linnaeus, 1758) is abundant and has a broad geographic distribution. It is one of the most important cereal pests. In Brazil, the economic losses associated with this aphid result mainly from the transmission of the barley yellow dwarf viruses.
2. Decision-making for the adoption of management measures must consider the initial population size, the potential for population increase, and the time when this population will reach levels at which the resulting damage is equal to the costs of control measures. Consequently, the establishment of management programmes and decision support systems should be based on models that estimate the potential population growth of this pest species.
3. Temperature is one of the main factors that determine the growth rate of insect populations. Generally, controlled experiments are designed to examine the relationship of temperature at fixed intervals in relation to the development phases of insects. In nature, thermal regimes are not constant, and population growth is the result of a series of combined events.
4. In this work, the effects of different thermal regimes on the population growth of R. padi were compared.
5. An agent-based model was used to estimate population growth, and the parameters defined in controlled regimes were compared with fluctuating temperatures under natural conditions.
6. The temperature-driven model presented here can serve as a tool to predict population growth and decision-making for aphid management.
7. The model structure and the proposed experimental design allow the addition of modules and layers of factors that can progressively affect the populations of aphids to gradually improve the model.