Automated system for surface photovoltage spectroscopy.

This paper details the development of a lab-made experimental setup for surface photovoltage spectroscopy (SPS) measurements using an open-source and Arduino® microcontroller to control a monochromator and some off-the-shelf electronic components. The experimental setup is interfaced to a computer, where LabVIEW® based software manages system control and data acquisition. We also report the design of a compact sample holder, simple and easy to manufacture and handle. Results of the application of SPS to the characterization of MoO3 thin films and semiconductor laser structures are presented to validate the performance of the setup, highlighting the effectiveness of SPS for the characterization of semiconductor materials and devices.

Molecular and epidemiological investigations of cryptosporidiosis in Cuban children.

Molecular and epidemiological studies of Cryptosporidium infections amongst 28 Cuban children (aged 2-8 years) with diarrhoea are described. As few of the younger infected children but most of the older infected children had been breastfed, short-term protection from maternal antibodies passed to infants during breastfeeding may result in a lack of cryptosporidial infection in infancy. This protection of breastfeeding children may, however, result in such children developing less anti-Cryptosporidium immunity of their own (than their bottle-fed counterparts), so that, by school age, the children who had been breastfed are those most likely to be found infected. In the present study, in contrast with the observations made during a previous study of cryptosporidiosis in Cuban children, vomiting was rare (7%) whereas abdominal pain was common (57%). These differences in expression of symptoms between studies may be age-related. As seen in other studies from similar countries, including those of the Caribbean and Latin America, C. hominis was found to predominate, the results of the successful molecular analyses revealing 10 C. hominis infections but no C. parvum. Subgenotyping (at the gp60 locus) indicated that the C. hominis infections included a wide range of subtypes, with isolates from three subtype families (Ia, Ib and Id) being detected.

Giardia infections in Cuban children: the genotypes circulating in a rural population.

Stool samples containing Giardia duodenalis cysts were collected from 95 primary-school children in central Cuba, and preserved by storing at -20 degrees C in 70% ethanol. Clinical data were collected for each child. Although 57% of the children were asymptomatic, the remaining 43% each reported between one and three symptoms. Following cyst quantification and isolation, molecular analyses were attempted on all cyst isolates, with the focus on the parasite's beta-giardin and glutamate-dehydrogenase (gdh) genes. Unfortunately, the cyst-preservation procedure appeared to have a deleterious effect on the cysts, since genotyping data could only be obtained for 20 of the 95 isolates. These data indicated, however, an approximately equal distribution between assemblage A (nine isolates) and assemblage B (11 isolates). Children found to be excreting relatively large numbers of cysts were more likely to be symptomatic than children who were excreting fewer cysts, and children with Giardia isolates from assemblage B were more likely to have symptomatic infections than children with isolates from assemblage A. Although considerable sequence variability was seen in the assemblage-B isolates, the assemblage-A isolates were relatively genetically homogeneous. This is the first publication from the Caribbean in which the Giardia genotypes circulating within the population have been identified, the first from the Americas providing information on associations between clinical presentation and the assemblage of the infecting Giardia, and the first to indicate that levels of cyst excretion may have clinical significance.

[Intestinal parasitic infections in 4 child day-care centers located in San Miguel del Padrón municipality, Havana City, 1998]. / Parasitosis intestinales en 4 círculos infantiles de San Miguel del Padrón, Ciudad de La Habana, 1998.

A coproparasitologic study was performed on 456 children aged 1-5 years from 4 day-care centers located in San Miguel del Padrón municipality during November 1998, with the aim of finding out the behaviour of the main intestinal parasites and particularly how Giardia lamblia was affecting this child population. Three fecal specimens were collected from each child in every other day, which were processed by coproparasitologic methods such as direct testing and Ritchie's concentration technique. The most frequently identified parasite was G. lamblia with 249 positive cases for a prevalence rate of 54.6%. The second one was Blastocystis hominis (29.6%) followed by Endolimax nana(23.9%). Coccidia like Crystosporidium parvum and Cyclospora cayetanensis exhibited low frequencies, 0.6 and 1.5% respectively, being the majority of the cases located in only one day care center. These results confirmed that G. lamblia is the most prevailing parasite in day care centers, with peak frequency values in 2-4y age group and no differences between sexes.

[The detection of antibodies, antigens and circulating immune complexes in acute and chronic fascioliasis. Preliminary results]. / Detección de anticuerpos, antígenos y complejos inmunes circulantes en las fascioliasis aguda y crónica. Resultados preliminares.

24 patients with fascioliasis were studied. 19 of them were in the chronic stage and 5 in acute stage. The presence of antigens and of circulating immune complexes (CIC) was detected in 100% of the patients suffering from acute fascioliasis with less than 30 days of evolution of the clinical symptoms; whereas coproantigens were present in 100% of the chronic patients. In this group it was observed a considerable number of cases with elevated levels of antibodies. 43.7% of the cases with CIC were detected by using the precipitation technique with PEG and that of Clq deviation. A highly significant correlation was found between the eggs counting and the CIC levels by both techniques. Another important correlation was established between the eggs counting and the levels of coproantigens.