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J R Shaw

Publications and source records attributed to J R Shaw.

35 records · Page 2Linked to original sources
PubMed1981

Schistosoma mansoni: an examination of the reproductive status of females from single sex infections.

The variation in the development of the reproductive system of female Schistosoma mansoni from single six infections is described. Vitelline cell development was assessed by staining for phenolic substances and the development of Mehlis' gland and the ovary by electron microscopy. Although there was considerable variation in the development of worms for individual mice harbouring infections of the same age, the men values indicated that there was a low level of differentiation and turnover of vitelline cells in worms 30-200 days post-infection. The proportion of females with possessed mature vitelline cells showed a general increase with age. The ovary was always in an immature stage but the development of Mehlis' gland showed some variation. The results suggest that the stimulus given by the male to the female is not necessarily to initiate development of the reproductive system but to increase the rate of development of the vitelline gland and to co-ordinate the development of the entire reproductive system.

Animals↗
PubMed1977

Schistosoma mansoni: differential cell death associated with in vitro culture and treatment with Astiban (Roche).

A simple technique for the maintenance in vitro of mature Schistosoma mansoni is described and critically assessed at the ultrastructural level. Females were cultured for 4--6 days with no apparent ultrastructural change, but after this period changes appeared in the cells of the ovary and vitelline gland. At a later stage (10--12 days) lipid bodies appeared in the parenchyma cells. These changes occurred in worms which were active, paired with males and were egg-laying. Thus the activity, pairing behaviour and egg-laying characteristics are not adequate to reveal the true morphological condition and presumably the physiological and biochemical status of cultured worms. This technique was used to study the effect of Astiban on females and the results were compared with worms treated in vivo. Astiban concentrations greater than 30 microgram/ml killed worms within 7--20 h and acted non-selectively. Astiban at low concentrations (10 microgram/ml) during short-term culture (1--3 h) resulted in a selective action of the drug on maturing vitelline cells. Thus, although the degree of cell damage caused by drug treatment was more severe and occurred earlier than the effects observed in worms cultured in vitro without drugs, both treatments resulted in differential cell death.

Animals↗
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Observations on the relation of environmental and behavioral factors to the occurrence of otitis media among Indian children.

Studies were conducted to assess the relation of environmental and behaviora factors to occurrence of acute suppurative otitis media (ASOM) among four populations of Indian children in Arizona. Episodes of ASOM were recorded for 1,428 children observed during the first year of life. Data obtained on the households and premises of these children included number of persons in the household, number of sleeping rooms, type of water supply and sewage disposal, type of heating and cooling, availability of electricity, method of infant feeding, distance to a health facility, and mother's education. The rates of ASOM for the four populations ranged from 1.1 to 2.2 attacks per child and differed significantly from each other, with one exception. The differences between populations apparently were not related to any of the factors evaluated. Additional analyses to evaluate the association of each factor with occurrence of ASOM included (a) a comparison of rates among children living in homes having each factor with rates among children living in homes lacking the factor, (b) a comparison of the frequency of each factor in homes of children who had no recorded attacks of ASOM with the frequency in homes of children who had three or more attacks (high-risk children), and (c) an evaluation of the relation between frequency of encounters for ASOM and the environmental factors. Results did not indicate that any environmental or behavioral factor observed was consistently or strongly associated with either the incidence of ASOM or the frequency of attacks. Similarly, no differences were apparent in the frequency of adverse environmental conditions in homes of infants with contrasting rates of ASOM. Rates of ASOM during the first year of life were not associated with either the presence or the absence of adverse environmental conditions.

Arizona↗
PubMedDate not supplied

Distribution of otitis media among four Indian populations in Arizona.

More than 75 percent of the cases of acute suppurative otitis media (ASOM) among Indian children observed from May 1974 through March 1979 were experienced by preschool children. About 60 percent of the children observed during the first year of life had one or more attacks of ASOM, and 34 percent had two or more. Among those who had ASOM before their first birthday, 75 percent of the attacks occurred between 3 and 9 months of age. About 73 percent of the initial attacks were recorded during the first year of life among children observed from 3 to 5 years; almost 90 percent occurred before the second birthday. Approximately 75 percent of the second attacks occurred within 4 months of the first. More than 70 percent of the initial attacks before age 1 were followed by 1 or more subsequent attacks during the next 12 months. When the initial attack occurred during the second year of life, subsequent attacks were experienced by less than half as many children. Children at high risk of serious ear disease, including hearing loss, are characterized by having an attack of ASOM before their first birthday followed by a second attack within 4 months of the first. Efforts to control and prevent ASOM should selectively be directed toward this group.

Acute Disease↗