Biomedical subjects
R H Webber
Publications and source records attributed to R H Webber.
The natural decline of Wuchereria bancrofti infection in a vector control situation in the Solomon Islands.
In a situation where filariasis and malaria are transmitted by the same vector, as seen here in the Solomon Islands, the Malaria Eradication Programme aimed at controlling the vector, was found to have an effect on both diseases. In an area of Choiseul island first surveyed by the author in 1970, three follow-up surveys were conducted--in 1974, 1975 and 1976. These showed a progressive decrease in persons infected. When the densities, especially the median microfilarial counts, were expressed as percentage values of the pre-spray survey, there was found to be a proportional decrease over eight years. It is possible that the Anopheline vector needs to be reduced less for the cessation of transmission of filariasis than for malaria. A theoretical ratio was calculated and supporting field evidence presented.
Comparison of counting chamber and measured blood films in microfilaria estimation.
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Anatomical study of the cervical sympathetic trunk and ganglia in the albino rat (Mus norvegicus albinus).
Nine adult albino rats of both sexes were studied. 16 sympathetic trunks and ganglia were dissected in detail in eight rats. The right and left superior cervical ganglion and the sympathetic trunk below the ganglion were removed from an additional rat. The cell bodies of these ganglia and the axons of the trunks were counted with the aid of light and electron microscopy. Considering the number and location of ganglia and patterns of branching, the rat's cervical sympathetic nervous system compares closely with man's. There appears to be a relationship between body size and myelination of preganglionic neurons in the cervical sympathetic trunks, with smaller animals having the least number of myelinated fibers.
Suppression and regeneration of rat bone marrow under the influence of methotrexate. An EM study.
Adult male rats were given daily injections of methotrexate for 12 days, during which time specimens of femoral bone marrow were taken for correlative light- and electron-microscopic study. After 12 days methotrexate was discontinued and specimens were taken the marrow recovered from the effect of methotrexate. Normal rat bone marrow was used as a basis of comparison. As methotrexate was administered, cell division ceased and the immature erythroblasts and myelocytes proceeded in the maturational process and a rapid hypocellularity of the marrow developed. Eosinophilic leukocytes, lymphocytes, large fat cells, erythrocytes, and phagocytic reticuloendothelial cells were the only formed elements remaining after 12 days of methotrexate treatment. Two days after methotrexate was discontinued, myeloblasts, myelocytes and proerythroblasts were plentiful, and on the third day the marrow exhibited an erythroid hyperplasia. By the eighth day all cell types were present though the marrow still was hypocellular. 14 days post methotrexate the marrow returned to normal.
Electrostimulation and morphologic study of the nerves to the bone marrow of the albino rat.
The innervation of the bone marrow of the albino rat was investigated by electrostimulation and morphological methods. Stimulation of the lumbar sympathetic trunks resulted in the release of reticulocytes and neutrophils into the circulating blood. The effects of stimulation on other cell types in the bone marrow could not be definitely established. It was concluded that the nerve fibers to the bone marrow were distributed to the arteries. It is postulated that the transmitter substance released at the autonomic nerve endings may have an effect upon the permeability of the venous sinusiods and the mobility of the blood cells in the marrow parenchyma resulting in their release into the circulating blood.
Vector control of filariasis in the Solomon Islands.
In Solomon Islands, filariasis is caused by the nocturnally perodic form of Wuchereria bancrofti and is transmitted by the same vectors of malaria. This study explores the control of this disease as an additional effect of the Malaria Eradication Programme.
Theoretical considerations in the vector control of filariasis.
In order to assist in assessing progress of vector control of filariasis a theoretical model is constructed, using retrospective data on infected persons removed to a vector-free situation. This shows that the decrease of microfilaraemia is not regular, but is gradual for the first 3 years and then more rapid, reaching zero at about 10 years. An estimate is made of the level to which the vector must be reduced before transmission of filariasis ceases, showing that the degree of efficiency required is considerably less than for malaria.
The nature of the reticulum cell of the bone marrow of the rat: an electron microscopic study of the effects of methotrexate.
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The sympathetic trunks of bats.
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Bone marrow response to stimulation of the sympathetic trunks in rats.
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The sympathetic trunks of a hibernator, the bat Myotis lucifugus.
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Accessory ganglia related to sympathetic nerves in the lumbar region.
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Distribution of fibers from nerve cell bodies in ventral roots of spinal nerves.
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Innervation and regeneration in orbitally transplanted limbs of Amblystoma larvae.
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Failure of chloroquine treatment for malaria in the highlands of Ethiopia.
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Comparison of the effect of insecticide-treated bed nets and DDT residual spraying on the prevalence of malaria transmitted by Anopheles anthropophagus in China.
In order to improve the control of malaria in a problem part of Hubei Province, China, where Anopheles anthropophagus is the vector of Plasmodium vivax, insecticide treatment of bed nets was introduced. The people were given the choice of DDT residual spraying, which had been used for many years, or deltamethrin treatment of their bed nets. Two counties, in which these 2 different methods had been introduced, and an untreated area were evaluated. DDT house spraying and insecticide treated bed nets were equally effective, but deltamethrin treatment was cheaper and so was considered the method of choice.
Surveillance for low-level malaria.
Due to good detection and control, malaria has reached very low levels in China with the result that existing methods of surveillance, taking blood slides from all fever cases and those with a common cold, are finding very few malaria cases among the millions of persons examined. Passive case detection agents in areas of moderate and low endemicity in Hubei Province, China, were instructed to indicate on the form associated with each slide whether the patient was considered to be a clinical case of malaria (group 1), was thought to have malaria but did not have all the features (group 2), had fever alone and was not thought to be a case of malaria (group 3), or merely had a common cold (group 4). In the low endemic area (slide positivity rate 0.23%), only 5 cases in group 3 and 4 in group 2 were detected per 10,000 examinations. It is recommended that these categories be discontinued in malarious areas of low endemicity, to encourage greater efficiency in detecting cases in groups 1 and 2. In the moderately endemic area, with a slide positivity rate of 4.19%, all categories, including group 4, were considered valuable for detecting malaria cases.