Biomedical subjects

David J Rogers

Publications and source records attributed to David J Rogers.

7 recordsLinked to original sources

PubMed2002

Climate change and the resurgence of malaria in the East African highlands.

The public health and economic consequences of Plasmodium falciparum malaria are once again regarded as priorities for global development. There has been much speculation on whether anthropogenic climate change is exacerbating the malaria problem, especially in areas of high altitude where P. falciparum transmission is limited by low temperature. The International Panel on Climate Change has concluded that there is likely to be a net extension in the distribution of malaria and an increase in incidence within this range. We investigated long-term meteorological trends in four high-altitude sites in East Africa, where increases in malaria have been reported in the past two decades. Here we show that temperature, rainfall, vapour pressure and the number of months suitable for P. falciparum transmission have not changed significantly during the past century or during the period of reported malaria resurgence. A high degree of temporal and spatial variation in the climate of East Africa suggests further that claimed associations between local malaria resurgences and regional changes in climate are overly simplistic.

Africa, Eastern↗

PubMed2002

Satellite imagery in the study and forecast of malaria.

More than 30 years ago, human beings looked back from the Moon to see the magnificent spectacle of Earth-rise. The technology that put us into space has since been used to assess the damage we are doing to our natural environment and is now being harnessed to monitor and predict diseases through space and time. Satellite sensor data promise the development of early-warning systems for diseases such as malaria, which kills between 1 and 2 million people each year.

Animals↗

PubMed2002

A quantitative evaluation of radiolabelled lectin retention on oral mucosa in vitro and in vivo.

Previous work has identified lectins that bind to the cells present on the oral mucosa for their potential use as a means of retaining a drug delivery system on the mucosal surfaces of the mouth. In this study, a radiolabelling technique was developed to allow the quantification of lectin binding to human buccal cells in vitro, and the retention of the lectins in the oral cavity of a rat model in vivo. Lectins were labelled with 99mTc using a cyclic diethylene triamine pentaacetic acid conjugation technique. In the in vitro study, human buccal cells were obtained by scraping the inner surface of the cheek. The suspended cells were exposed to the labelled lectin solution for 30 min and after washing with buffer the activity associated with the cells determined. In the in vivo study, male Wistar rats were briefly anaesthetized during which 10 microl of a solution containing labelled lectin was applied into the buccal pouch. At set times the rats were killed and the lower buccal cavity mucosal tissue and tongue dissected out and monitored for bound lectin. The in vitro study indicated that the lectins from Arachis Hypogaea, Canavalia ensiformis and Triticum vulgaris bound to oral mucosal cells. The T. vulgaris lectin showed the greatest binding, calculated to be 6.77 x 10(9) molecules per cell. The in vivo retention of C. ensiformis and T. vulgaris lectins on rat oral mucosal tissue was also evident. The T. vulgaris lectin showed significantly higher levels of retained lectin after 30 min (29.54 +/- 4.20 microg SD) on the oral mucosal tissue and 28.37 microg (+/-2.13 SD) on the tongue and was still detected at similar levels after 2 h. These studies indicate that significant lectin binding to human buccal cells occurs in vitro and retention in an animal model occurs for over 2 h in vivo. The T. vulgaris lectin showed most promise for further work.

Animals↗

PubMed2002

Mapping bovine tuberculosis in Great Britain using environmental data.

The incidence of bovine tuberculosis (BTB) is increasing in Great Britain, exacerbated by the temporary suspension of herd testing in 2001 for fear of spreading the much more contagious foot and mouth disease. The transmission pathways of BTB remain poorly understood. Current hypotheses suggest the disease is introduced into susceptible herds from a wildlife reservoir (principally the Eurasian Badger) and/or from cattle purchased from infected areas, while the role of climatic factors in transmission has generally been ignored. Here, we show how remotely sensed satellite data, which provide good indicators of a variety of climatic factors, can be used to describe the distribution of BTB in Great Britain in 1997, and suggest how such data could be used to produce BTB risk maps for the future.

Animals↗

PubMed2002

Hot topic or hot air? Climate change and malaria resurgence in East African highlands.

Climate has a significant impact on malaria incidence and we have predicted that forecast climate changes might cause some modifications to the present global distribution of malaria close to its present boundaries. However, it is quite another matter to attribute recent resurgences of malaria in the highlands of East Africa to climate change. Analyses of malaria time-series at such sites have shown that malaria incidence has increased in the absence of co-varying changes in climate. We find the widespread increase in resistance of the malaria parasite to drugs and the decrease in vector control activities to be more likely driving forces behind the malaria resurgence.

Africa, Eastern↗

PubMed2002

A response to the aim of eradicating tsetse from Africa.

An ambitious plan to eradicate tsetse, and therefore tsetse-transmitted trypanosomiases, from Africa was launched at the 36th Organization of African Unity summit meeting (Togo, July 2000) in a bold attempt to re-focus attention on one of Africa's greatest scourges. This plan involves the use of the sterile insect technique to achieve final eradication in areas where the fly is suppressed by more conventional methods (such as traps and targets). In this article, the current aims of this project are questioned on historical, ecological, logistical and financial grounds.

Africa↗

PubMed2002

Development, survival, body weight, longevity, and reproductive potential of Oemena hirta (Coleoptera: Cerambycidae) under different rearing conditions.

Oemona hirta (F.) is a New Zealand native longicorn beetle, whose larvae bore into the wood of branches and stems of living trees and vines, causing serious damage. To explore effective methods for maintaining laboratory colonies and biology of immature stages of this species we evaluated four laboratory rearing methods with both natural and artificial diets and compared biological parameters of laboratory colonies with those of field-collected insects. On an artificial diet, approximately 40% of neonate and 70% of autumn- and 11% of winter-collected larvae reached adulthood. Neonate larvae could not complete their development in cut poplar (Populus nigra variety italica Koehne) twigs; however, when twigs were standing in water >46% of neonate larvae survived to adulthood. Mean larval development time ranged from approximately150 to almost 300 d, depending on rearing methods. Mean pupal stage ranged from 15 to 19 d. Adult females were significantly heavier than males. Although adult females from field-collected twigs and reared on the artificial diet had similar mean body weight, which was significantly greater than that of other rearing colonies, the potential fecundity was the highest in the former (83.1 +/- 29.4 eggs) and the lowest in the latter (33.5 +/- 9.1 eggs). In all laboratory-reared and field-collected insects, the total number of eggs produced (eggs laid + eggs that remained in dead female body) by females was positively correlated with their body weight. When larvae fed on the artificial diet, there was no positive correlation between the number of eggs successfully laid and female body weight. However, when larvae lived on natural food, a positive correlation was found. In laboratory colonies, mean longevity of females (36 to 52 d) was slightly greater than that of males (30 to 50 d) without significant difference between sexes but in the adults from field-collected twigs, males (52 d) lived significantly longer than females (33 d). In terms of time, labor, and the number of resulting adults, collecting larvae in the field in autumn and then transferring them onto artificial diet is the most effective method for maintaining a laboratory colony.

Animals↗