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Cell Cycle,
2009]
The oxidative damage theory of aging once seemed almost proven. Yet recently the buzzards have been assembling in the blue skies above it. New challenges to the theory from work using nematode worms seem set to bring them down to peck at its bones. But is the theory really dead, or does it just need to be modified?
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Ciba Found Symp,
1987]
Human lymphatic filariasis is caused mainly by Wuchereria bancrofti, Brugia malayi and Brugia timori. Of the estimated 90.2 million people infected, more than 90% have bancroftian and less than 10% brugian filariasis. The distribution and transmission of the disease are closely associated with socioeconomic and behavioural factors in endemic populations. Urban W. bancrofti infection, as seen in South-East Asia, is related to poor urban sanitation, which leads to intense breeding of Culex quiquefasciatus, the principal vector. Rural strains of W. bancrofti are transmitted primarily by Anopheles spp. and Aedes spp. mosquitoes. Brugian filariasis is mainly a rural disease transmitted by Mansonia, Anopheles and Aedes spp. mosquitoes. The periodic form of B. malayi is principally a human parasite, whereas the subperiodic form is zoonotically transmitted in some countries. The control of filariasis has relied on chemotherapy, vector control and reduction of human-vector contact. Although eradication of W. bancrofti and periodic B. malayi can be achieved, it is possible only to reduce transmission of zoonotic subperiodic B. malayi in some areas. A rational approach to control should consider ecological, socioeconomic and behavioural factors and, where feasible, integrate control programmes into the delivery system for primary health care.
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East Afr Med J,
1997]
Apoptosis differs from necrosis in that no inflammatory changes occur. The understanding of apoptosis was greatly improved by the discovery of a natural model of apoptosis in Caenorhabditis elegans, a nematode worm. The study of this worm led to the discovery of two sets of genes, the prosuicide genes and the antisuicide genes which control apoptosis. Apoptosis is an active process that involves w activation of specific enzymes. The understanding of the molecular biology of apoptosis may in future lead to the availability of a potent weapon to use against cancer and to modify cell death that occurs in the neurodegenerative disorders.AD - Department of Morbid Anatomy and Forensic Medicine, Faculty of Basic Medical Sciences, College of Health Sciences, Obafemi Awolowo University, Ile-Ife, Nigeria.FAU - Olasode, B JAU - Olasode BJLA - engPT - Journal ArticlePT - ReviewPT - Review, TutorialCY - KENYATA - East Afr Med JJID - 0372766SB - IM
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[
Mech Ageing Dev,
2002]
Accurate measures of physiological and metabolic condition could provide more insight into how longevity genes and signalling pathways affect global metabolic activity and life span. The present study is essentially a methodological treatise in which we describe and evaluate a number of methods to assess changes of metabolic activity in ageing Caenorhabditis elegans. Oxygen consumption and CO(2) production rate assays, and measurement of the heat output by microcalorimetry are performed using live worms. For other assays, frozen (-75 degrees C) samples can be used. A lucigenin-mediated light production assay provides information on the metabolic capacity (scope for metabolic activity) of the worms just before freezing. Assaying ATP and ADP levels provides a measure of the instantly available energy. The XTT assay measures the activity of enzymes that can reduce XTT. Blue fluorescence emitted at 420-470 nm is a potentially useful biomarker of the rate of ageing. A protein quantification protocol for normalising all data for quantitative comparisons is presented. We illustrate how these methods can validate or disprove models of gene action inferred from molecular identification.
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Endocr Metab Immune Disord Drug Targets,
2012]
Filarial infections are characterized by immunopathological phenomena, that are responsible for the onset of often dramatic pathological outcomes, such as blindness (Onchocerca volvulus) and elephantiasis (W. bancrofti). In addition, the long-term survival (as long as 10 years) of these parasites in otherwise immunocompetent hosts indicates that these nematodes are capable of manipulating the host immune response. The ground-breaking discovery of the bacterial endosymbiont Wolbachia, which resides in most filarial nematodes causing disease, has led to increasing interest in the role it may play in immuno-modulation, pro-inflammatory pathology and other aspects of filarial infection. Indeed, Wolbachia has been shown to be responsible for exacerbating inflammation (as in river blindness), while at the same time blocking efficient elimination of parasites through the host immune response (Onchocerca ochengi). While studies aimed at identifying Wolbachia as a potential target for anti-filarial therapy are at the forefront of current research, understanding its role in the immunology of filarial infection is a fascinating field that has yet to uncover many secrets.
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Clin Microbiol Infect,
2011]
Lymphatic filariasis (LF) and onchocerciasis are parasitic nematode infections that are responsible for a major disease burden in the African continent. Disease symptoms are induced by the immune reactions of the host, with lymphoedema and hydrocoele in LF, and dermatitis and ocular inflammation in onchocerciasis. Wuchereria bancrofti and Onchocerca volvulus, the species causing LF and onchocerciasis in Africa, live in mutual symbiosis with Wolbachia endobacteria, which cause a major part of the inflammation leading to symptoms and are antibiotic targets for treatment. The standard microfilaricidal drugs ivermectin and albendazole are used in mass drug administration programmes, with the aim of interrupting transmission, with a consequent reduction in the burden of infection and, in some situations, leading to regional elimination of LF and onchocerciasis. Co-endemicity of Loa loa with W. bancrofti or O. volvulus is an impediment to mass drug administration with ivermectin and albendazole, owing to the risk of encephalopathy being encountered upon administration of ivermectin. Research into new treatment options is exploring several improved delivery strategies for the classic drugs or new antibiotic treatment regimens for anti-wolbachial chemotherapy.
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Neurotoxicology,
2008]
Manganese (Mn) is a transition metal that is essential for normal cell growth and development, but is toxic at high concentrations. While Mn deficiency is uncommon in humans, Mn toxicity is known to be readily prevalent due to occupational overexposure in miners, smelters and possibly welders. Excessive exposure to Mn can cause Parkinson''s disease-like syndrome; patients typically exhibit extrapyramidal symptoms that include tremor, rigidity and hypokinesia [Calne DB, Chu NS, Huang CC, Lu CS, Olanow W. Manganism and idiopathic parkinsonism: similarities and differences. Neurology 1994;44(9):1583-6; Dobson AW, Erikson KM, Aschner M. Manganese neurotoxicity. Ann NY Acad Sci 2004;1012:115-28]. Mn-induced motor neuron diseases have been the subjects of numerous studies; however, this review is not intended to discuss its neurotoxic potential or its role in the etiology of motor neuron disorders. Rather, it will focus on Mn uptake and transport via the orthologues of the divalent metal transporter (DMT1) and its possible implications to Mn toxicity in various categories of eukaryotic systems, such as in vitro cell lines, in vivo rodents, the fruitfly, Drosophila melanogaster, the honeybee, Apis mellifera L., the nematode, Caenorhabditis elegans and the baker''s yeast, Saccharomyces cerevisiae.
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East Afr Med J,
1994]
The nematode parasites Wuchereria bancrofti, Brugia malayi and B. timori are the causative agents of human lymphatic filariasis. Of the estimated 90 million infections world-wide, W. bancrofti is responsible for over 80 million cases and is the only known aetiologic agent in the African Region. Numbers of infected persons are on the increase world-wide due to rural-urban migrations which result in mushrooming of shanty towns often encouraging formation of favourable mosquito breeding-sites. Development of insecticide resistance by the vector mosquitoes; the toxicity and high cost of available effective formulations, and the deteriorating global economy aggravate this situation. Human lymphatic filariasis is more of a morbidity than a mortality-causing disease but can be devastating and crippling at both the individual and community levels. Unlike many parasitic infections, lymphatic filariasis can easily be controlled. The success of any control programme depends on sensitive diagnostic techniques and this is the challenge. Identification of all true positive individuals in an endemic community can be problematic since filariasis is spectral and no single diagnostic technique can be expected to be uniformly sensitive in all situations. Availability of new biotechnologies has given impetus to formulations of several diagnostic tools. New diagnostic methods and improvements on the traditional ones is the topic of this review. Recommendations in view of their field applications are also discussed.
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Immun Infekt,
1980]
The significance of tropical heminthiases for the populations of tropical countries is discussed and a survey on the incidence of these parasitic infections is given. The difference between infection and disease is explained, and the properties of an ideal drug for combatting the different diseases are described. After a short comment on the goals of the primary and secondary screening procedures the authors refer to WHO's Special Programme for Research and Training in Tropical Diseases. As to the different forms of filariasis, the most important problem is onchocerciasis due to the high rate of blindness. The existing drugs (suramin DEC) are evaluated, however, there is a need for a safe, macrofilaricidal drug. The chemotherapy of filariasis caused by W. bancrofti and B. malayi and the drugs used is also discussed. Thereafter, a survey on the chemotherapy of schistosomiasis and the drugs at hand and in development is given with special reference to praziquantel. Chemotherapy of opistorchiasis and clonorchiasis is still unsatisfactory. The problems arising from this situation are mentioned. Up to now, we have a similar situation in hydatid disease, caused by Echinococcus species. The therapy of choice is operation, however, in animal experiments it could be demonstrated that benzimidazole derivatives inhibit the growth of cysts what indicates the possibility of chemotherapy in man also. Finally, a survey is given on anthelminthic drugs for the therapy of different forms of intestinal helminthiasis with special regard to ancylostomiasis.
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Exp Cell Res,
2014]
One of the most important ways in which animal species vary is in their size. Individuals of the largest animal ever thought to have lived, the blue whale (Balaenoptera musculus), can reach a weight of 190 t and a length of over 30 m. At the other extreme, among the smallest multicellular animals are males of the parasitic wasp, Dicopomorpha echmepterygis, which even as adults are just 140 m in length. In terms of volume, these species differ by more than 14 orders of magnitude. Since size has such profound effects on an organism's ecology, anatomy and physiology, an important task for evolutionary biology and ecology is to account for why organisms grow to their characteristic sizes. Equally, a full description of an organism's development must include an explanation of how its growth and body size are regulated. Here I review research on how these processes are controlled in the nematode, Caenorhabditis elegans. Analyses of small and long mutants have revealed that in the worm, DBL-1, a ligand in the TGF superfamily family, promotes growth in a dose-dependent manner. DBL-1 signaling affects body size by stimulating the growth of syncytial hypodermal cells rather than controlling cell division. Signals from chemosensory neurons and from the gonad also modulate body size, in part, independently of DBL-1-mediated signaling. Organismal size and morphology is heavily influenced by the cuticle, which acts as the exoskeleton. Finally, I summarize research on several genes that appear to regulate body size by cell autonomously regulating cell growth throughout the worm.