W-band tunable, multi-channel, frequency comb Doppler backscattering diagnostic in the ASDEX-Upgrade tokamak.

This article presents the design, implementation, and first data of a uniquely flexible, multi-channel, frequency comb Doppler backscattering diagnostic recently made operational in the ASDEX-Upgrade tokamak [A. Gruber and O. Gruber, Fusion Sci. Technol. 44, 569 (2003)]. It uses a double side-band signal fed into a ×6 frequency multiplier to produce a multiple-frequency output spectrum. Seven of these frequencies are simultaneously measured in the receiver via a two-step frequency down-conversion and traditional I/Q demodulation. The frequency comb spectrum is fully tunable to sit anywhere in the W-band. The inter-frequency separation is also uniquely tunable remotely between 0.1 and 6 GHz without any hardware changes. The diagnostic can be operated in both O and X-mode polarizations and at both oblique and normal incidence to the cutoff layer. The time evolution of backscattered signals, in excess of 30 dB, from seven distinct frequencies sampled simultaneously is presented across an L-to-H-mode confinement regime transition.

Ticks (Ixodida: Ixodidae) parasitising humans in Uruguay.

During routine collections between November 1999 and November 2002, three species of tick (Amblyomma tigrinum, Amblyomma triste and Rhipicephalus sanguineus) were found on humans in southern Uruguay. The finding of R. sanguineus and A. triste on humans is of particular concern because these tick species may be involved in the transmission of the pathogens causing human rickettsioses, a type of disease already known to occur in Uruguay.

National prevalence of larval echinococcosis in sheep in slaughtering plants Ovis aries as an indicator in control programmes in Uruguay.

Diagnostic surveys carried out on ovine larval echinococcosis in slaughtering plants at a national level in 1998 made it possible to meet several objectives, i.e. to estimate the existing levels of prevalence, to evaluate the effectiveness of the control actions applied by the Programme against Hydatidosis and to contribute to the improvement of the health information systems for epidemiological surveillance. The work included sheep (Ovis aries), both lambs (2-4 teeth) and adults (6-8 teeth). A random sample was performed among sheep from the plants that slaughter the majority of animals in the country. The sample included 22 animals per herd, and it involved removing their offal (liver, lungs and heart) and processing serial sections at the laboratory. The histopathological studies were performed on the lesions that could not be adequately identified at gross examination, and those that were so small that had to be submitted for confirmation of the diagnosis. Of the 2035 animals that were examined, 1019 were lambs (2-4 teeth) and 1016 were adults (6-8 teeth). The prevalence of larval echinococcosis was 7.7% in lambs and 18.0% in adults. The overall prevalence in the liver was 8.5 and 8.0% in the lungs. As to the characteristics of the morphologic structures of the larvae, in younger animals 29% of the lesions were calcified, and 71.0% were hyaline, while in older animals the proportions were 34.4% calcified versus 65.6% hyaline. Other conditions found in the liver parenchyma included: white stain (0.8%), caseous lymphadenitis (3.0%), abscess (0.4%), larvae of Taenia hydatigena (5.1%), Fasciola hepatica (3.9%). And 1.7% of the animals presented larvae of Taenia ovis in the cardiac muscle. Previous surveys carried out in 1994 using the same methodology showed a prevalence of 15.2% in 2-4 teethed animals and 33.9% in 6-8 teethed animals, thus confirming that rates have decreased by 49.6 and 47.0%, respectively. The data obtained reflect the reduction of areas contaminated with eggs of Echinococcus granulosus, which would cause a loss in immunity against this parasite after a certain time. Prevalence of larvae T. hydatigena and T. ovis could change if more sites were considered, a fact that was confirmed in studies carried out in our country. The species O. aries must be used as an indicator in the control programmes, especially in the category of 2-4 teethed lambs. The fact they are not as frequent in our market must be considered; in 1998 they accounted for only 3.0% of the total numbers of animals.

Control of Echinococcus granulosus in Uruguay: evaluation of different treatment intervals for dogs.

This study attempted control of transmission of Echinococcus granulosus from dogs to sheep in different areas in the Department of Florida, Uruguay, by treating dogs with praziquantel at intervals of 6, 12 and 16 weeks. The 6-week interval was based on the prepatent period of infection with E. granulosus, the 12- and 16-week intervals were based on the rate of reinfection with tapeworms in dogs in the area. Dogs had become reinfected with E. granulosus between 2 and 4 months after treatment, whereas they became reinfected with the Taenia spp. tapeworms within 2 months of treatment. One year after the start of treatments sentinel lambs were born and grazed the farms in the three treatment areas. Approximately, 15 months later when the sentinel lambs were killed and examined for parasites the six weekly treatments had stopped the transmission of E. granulosus to the sentinel lambs. Treatment of dogs at 12- and 16-week intervals failed to stop transmission of E. granulosus but both the numbers of farms and the numbers of sheep infected with E. granulosus were lower where dogs received 12 weekly treatments compared with dogs receiving 16 weekly treatments and a fourth area where dogs had received no treatments (chi(2)P=0.002). Lambs continued to become infected with the Taenia spp. tapeworms in all the areas. Control was complicated by large changes in the dog population. From a starting population of 1164 dogs in the three treated areas, 832 new dogs, most of these adult hunting dogs, entered the population and 793 dogs were lost from the population.

Rates of reinfection with Echinococcus granulosus, Taenia hydatigena, taenia ovis and other cestodes in a rural dog population in Uruguay.

A survey was undertaken to determine both the prevalence of, and reinfection rates with Echinococcus granulosus and other cestodes in the Department of Florida, Uruguay. Baseline prevalence was determined in 303 rural dogs which then, in 4 groups, were re-examined 2, 4, 8 or 12 months later. Baseline prevalences for E. granulosus, Taenia hydatigena, Taenia ovis and Dipylidium caninum were 13.2, 13.9, 2.3 and 13.2%, respectively. The frequency distribution of E. granulosus was over-dispersed. Dogs in the population became infected with E. granulosus between 2 and 4 months after treatment (prevalences at 2, 4, 8 and 12 months were 0, 6.8, 18.6 and 27.9%, respectively). There was no indication that there was a predisposition of dogs to infection with the Odds Ratio being 1.0. Dogs were infected with T. hydatigena and D. caninum within 2 months and with T. ovis between 2 and 4 months after treatment. The implications of these different rates of reinfection in the dog population on anthelmintic control strategies against cystic echinococcosis are discussed.

Transmission dynamics of Echinococcus granulosus, Taenia hydatigena and Taenia ovis in sheep in Uruguay.

A base-line survey was carried out on the transmission dynamics of Echinococcus granulosus, Taenia hydatigena and Taenia ovis in sheep in the Department of Florida, Uruguay. Mean life expectancy at birth of the sheep population in this Department was estimated at 3.5 and 4.8 years for male and female sheep, respectively. Both intensity and prevalence of E. granulosus infection increased with age providing no evidence that immunity was acquired in the population. This revealed that E. granulosus was only relatively stable and in an equilibrium endemic steady state with an estimate of the basic reproduction ratio (Ro) of about 1.2. The mature larval population in sheep was over-dispersed with parameter k, from fitting a negative binomial, being 0.199 and 0.556 in 42- and 54-month-old sheep, respectively. The mean number of cysts increased by 1.05 cysts per year and the infection pressure was calculated as 0.174 infections per year, implying that each infection consisted of 693.6 eggs to produce 6.03 cysts. Neither intensity nor prevalence of infection with T. hydatigena or T. ovis increased with age. This indicated that immunity was acquired to reinfection by both parasites and they were in an equilibrium hyperenedemic steady state with an estimated Ro of 4.2-5.8. Viability and fertility of E. granulosus, and viability of T. hydatigena cysts in the older age groups were low. The effects of the different transmission levels of the parasites on potential control strategies are discussed.

Fiberoptic endoscopy in the diagnosis of retained gastric antrum.

Recurrent peptic ulcer following surgery has been extensively studied, but its causes are not always clear. Difficulties in the differential diagnosis of the various possible factors can be very puzzling, since most of the methods described fail to provide a reliable definitive diagnosis. In the present study the authors report on the results obtained with the use of fiberoptic endoscopy complemented by biopsy of the mucosa of the duodenal stump for the diagnosis of retained gastric antrum in recurrent ulcer following B-II type gastrectomy. Considering the good results obtained with this method in 20 out of 23 patients, with a high degree of accuracy in association with biopsy and without any complications, it is strongly recommended whenever there is a possibility that retained antrum is the cause of recurrent peptic ulcer.