Deep versus surface learning with multimedia in nursing education development and evaluation of WoundCare.

Examination of the software design-learning relationship is mandatory if significant benefits are to be derived from the development and use of Interactive multimedia in nursing education. This article reports on the development and student evaluation of WoundCare: An Interactive Learning Program for Health Professionals (version 1.0a). Of particular interest to those involved in nursing education is the extent to which the learning activities incorporated in WoundCare promote "deep" rather than "surface" learning. Specific design features believed to facilitate and inhibit deep learning are identified. Modifications that could increase the learning effectiveness of WoundCare and other interactive multimedia programs are proposed.

[Morphology of the teguments of Schistosoma haematobium; comparison with S. curassoni, S. bovis and S. intercalatum]. / Morphologie des téguments de Schistosoma haematobium; comparison avec S. curassoni, S. bovis et S. intercalatum.

Study by SEM of the anterior dorsal teguments of male Schistosoma haematobium from infected rodents. Only paired males, at least hundred days post infection, display a typical morphology. Differentiation from other closely related species obtained experimentally from rodents is possible: bovis: no spines on the tubercles; haematobium: tubercles 10 to 15 microns wide with closely packed spines; curassoni: tubercles over 15 microns wide, with large, closely packed spines; intercalatum: tubercles under 10 microns wide, with scattered spines. It is suggested that the three haematobium genotypes A, B and D are slightly different: A: pointed spines, numerous small additional spines between the tubercles; B: pointed spines, no small additional spines between the tubercles; D: blunt spines. Moreover, the lengths of the prepatent periods in the molluscs of the three S. haematobium genotypes are possibly different: A 72-86 days, B 38-46 days, D 55-58 days. The differentiation of A, B and D is supported by limited data and conclusions on this particular aspect are presented only as a working hypothesis.

Relationships between cercarial indices of Schistosoma haematobium, S. bovis and S. curassoni from Senegal and the isoenzyme genotypes of the adult worms.

S. haematobium and S. curassoni appear to consist of three and two G6PDH genotypes respectively whereas only a single genotype has been observed in S. bovis. This genotype corresponds to one of those exhibited by S. curassoni, but the two species may be distinguished using the AcP enzyme system. The antero-dorsal cercarial indices for S. haematobium gave a mean of 0.78 ranging from 0.67 +/- 0.03 to 0.90 +/- 0.11; S. curassoni gave a mean of 1.11, ranging from 1.00 +/- 0.05 to 1.23 +/- 0.14 and S. bovis a mean of 1.30 within the range 1.01 +/- 0.25 to 1.67 +/- 0.18. From these data it is apparent that there is some correlation between antero-dorsal Cl and enzyme genotype: nevertheless the variation in Cl is somewhat greater than that observed in enzyme genotypes. Generally, Cl values lower than 0.90 can be considered to be due to S. haematobium, those above 1.15 to be S. bovis and intermediate values of 0.90-1.15 indicate S. curassoni.

[Morphology of the teguments of Schistosoma bovis; variations linked to the vertebrate host; comparison with S. curassoni]. / Morphologie des téguments de Schistosoma bovis; variations selon l'hote vertébré; comparaison avec S. curassoni.

S. E. M. study of the dorsal anterior one third of male Schistosoma bovis and of the anterior ventral border of the gynaecophoric duct. S. bovis was previously described as possessing spineless tubercles. This is so in specimens obtained from experimentally infected rodents, but in cattle, on the contrary, when conditions are favourable, teguments have spiny tubercles. Two morphological types have been observed: the first in Bos taurus from Sardinia, the second in domestic (Bos indicus) and wild (Hippotragus equinus and Damaliscus korrigum) bovids from Senegal, Tchad and Centrafrican Republic.

Schistosoma mansoni from naturally infected Rattus rattus in Guadeloupe: identification, prevalence and enzyme polymorphism.

An enzymatic comparison has been made between isolates of Schistosoma mansoni from rats and humans in Guadeloupe and a Burundi isolate of S. rodhaini. Analyses of LDH, MDH, AcP, PGM, GPI, G6PDH and HK by isoelectric focusing provided no evidence for the involvement of S. rodhaini in the recent evolution of the schistosomes currently endemic in Guadeloupe. No distinction could be made between murine and human isolates of S. mansoni and it is suggested that murine schistosomiasis should not therefore be ignored in control programmes. Rattus rattus were captured at seven sites around the island; of 142 examined, 48 were positive for schistosomes. Differences in prevalence between habitats were marked and only small changes in prevalence were observed in localities sampled in 1982 and 1983. Animals with the greatest worm burdens were associated with areas of high prevalence, and age-related changes in worm burden were observed. Two alleles, a and b, at the MDH-1 locus of S. mansoni from rats were identified. Differences in the overall frequencies of these alleles were observed for schistosomes from different localities. Allelic frequencies representative of schistosomes from rats at four localities were stable from 1982 to 1983. The majority of positive animals, even those with light worm burdens, were found to be infected with a number of different schistosome genotypes.

Bulinus tropicus, a natural intermediate host for Schistosoma margrebowiei in Lochinvar National Park, Zambia.

Snails, provisionally identified as Bulinus tropicus, on the basis of chromosome number, egg protein profile, AcP and HBDH enzymes of the digestive gland, and radular morphology, from Lochinvar National Park, Zambia have been demonstrated to transmit Schistosoma margrebowiei naturally. The identification of the unpaired male schistosomes was confirmed by PGM and AcP analyses. The observations confirm earlier epidemiological predictions, and add another species of mollusc to the two, B. forskalii and B. scalaris, known to be natural intermediate hosts of S. margrebowiei.

Bulinus tropicus from Central Kenya acting as a host for Schistosoma bovis.

One hundred and twelve snails were collected from two habitats on the Mau Escarpment, Kenya and were provisionally identified as Bulinus tropicus from the characteristics of their shell and soft parts, chromosome number (n = 18), electrophoresis of egg protein on cellulose acetate strip and isoelectric focusing of AcP, GPI, HBDH, MDH and PGM digestive gland enzymes. Of the 55 specimens examined alive in London, 10 were infected with amphistome and schistosome larvae, 9 with amphistome larvae and the remainder were uninfected. The GPI and MDH separations of known infected snails showed two distinct areas of activity: host and parasite. Individual hamsters were exposed to schistosome cercariae emanating from each snail with a double infection (apart from one which died prematurely) and examination of the resulting adult worms showed that all were monomorphic for AcP with a band of enzyme activity at pH 6.45, characteristic of Schistosoma bovis. Examination of eggs found in two infections proved to be S. bovis in shape and size. Exposure of laboratory-bred snails of B. tropicus from the Mau Escarpment and other populations of B. tropicus proved negative. Thus, it is suggested that the presence of the amphistome infection may have a suppressive effect on the immune system of the snail, thereby allowing S. bovis to develop.

Observations on Schistosoma intercalatum in south-east Gabon.

Observations were made in the field and laboratory to determine the strain characteristics of Schistosoma intercalatum in south-east Gabon. For an isolate from Franceville, data are given for egg shape, behaviour of cercariae, seven enzyme systems separated by isoelectric focusing, and intermediate host specificity. Isolates from Cameroun (Edea) and Zaire (Kisangani) were included in a comparative study of the enzymes; Franceville and Edea isolates resembled each other but differed from the Zaire isolate in hexokinase and phosphoglucomutase. The Franceville isolate was polymorphic in phosphoglucomutase and glucosephosphate isomerase. The sum of characters indicates that S. intercalatum as known from south-east Gabon belongs to the strain found in Cameroun and western Gabon, rather than to the strain known from Zaire. More information is needed on strain distribution, particularly for an area including western Zaire and the Republic of the Congo, which appears to separate the two known strains.

Enzyme analysis of Schistosoma haematobium.

Results are reported of enzyme analyses, by isoelectric focusing in polyacrylamide gels, of adult Schistosoma haematobium worms derived from 22 isolates originating from 13 countries. Polymorphisms have been identified in the glucose-6-phosphate dehydrogenase (G6PD) and phosphoglucomutase (PGM) systems. Certain forms appear to be restricted in their geographical distribution and their occurrence outside their usual areas suggests human population movements resulting in mixing of parasite strains. The possible implications of minor variations in some PGM patterns and the apparent absence of heteropolymer fractions in presumed G6PD heterozygotes are discussed. The use of the technique to detect natural multiple miracidial infections in snails is reported and discussed.

Hybrids between Schistosoma haematobium and S. mattheei and their identification by isoelectric focusing of enzymes.

Some biological features of F1 hybrids between South African strains of Schistosoma haematobium and S. mattheei are described and compared with those of both parental species. The distinctive patterns of the G6PD and PGM isoenzymes, resolved by isoelectric focusing, of both species and of the hybrid are defined and the results of enzyme analyses of parasites isolated from human infections in the Transvaal are reported. These show that hybridization does occur naturally in man and that the shape of the eggs produced is not necessarily a guide to the genetic constitution of the enclosed larvae. The experimentally produced F1 hybrids exhibit heterosis in their increased infectivity to both snails and hamsters, in their more rapid growth and earlier maturation and in the increased daily egg production per female worm when compared with both of the parental species. The possible practical implications of this are discussed.

Observations on an isolate of Schistosoma bovis from Tanzania.

The eggs of Schistosoma bovis isolated from Misungwi, Tanzania measure 211.1 micrometer +/- 18.4 long and 66.7 micrometer +/- 5.4 wide. The parasite is naturally transmitted by Bulinus africanus and is compatible in the laboratory with snails belonging to the B. truncatus. B. forskali, and B. reticulatus groups. The compatibility with B. africanus group snails is shared with isolates from Kenya and Sudan but not with S. bovis from more northern distributions. Enzyme analyses were carried out by isoelectric focusing. In adult worms, phosphoglucomutase (PGM), hexokinase (HK), malate dehydrogenase (MDH), and lactate dehydrogenase (LDH) proved to be monomorphic whereas two types of glucosephosphate isomerase (GPI), three types of glucose-6-phosphate dehydrogenase (G6PDH), and two types of acid phosphatase (AcP) were identified. Differences in the pI values of gPI and MDH of snail digestive glands and of larval parasites allowed the intramolluscan stages to be characterised. The GPI heterogeneity encountered was common both to the larval and adult parasites. The enzyme types identified in S. bovis are discussed both from an intra- and interspecific viewpoint.