Meconial peritrophic matrix structure, formation, and meconial degeneration in mosquito pupae/pharate adults: histological and ultrastructural aspects

The noncellular peritrophic matrix (PM) that forms around the food bolus in the midgut of many arthropod species may influence the fate of ingested microbes. In mosquitoes, PMs have been identified in the pupal as well as larval and adult stages. In pupae, the PMs surround the meconium, the sloughed larval midgut epithelium. Meconial PM1 (MPM1) forms early in the pupal stadium, and a second meconial PM (MPM2) sometimes forms around the time of adult emergence. A recent study suggests that MPMs contribute to the sterilization of the adult midgut by sequestering microorganisms ingested during the larval stage, which, along with remaining meconial material, are egested after adult emergence. We have compared MPM1 formation and patterns of meconial degeneration in representative species in five mosquito genera and identified a temporal association between MPM1 formation, meconial degeneration, and apolysis. Ultrastructural study of MPM1 and MPM2 in Aedes aegypti (L.) revealed that MPM1 seems to be structurally different from either the larval or adult PMs, whereas MPM2 more closely resembles PM formed around a bloodmeal in adult females. Our results are consistent with the microbial sequestration role.

Small-diameter (2 mm) laparoscopy in the evaluation of liver disease

BACKGROUND

Percutaneous liver biopsy fails to demonstrate cirrhosis in approximately 32% of cases when compared with laparoscopy with liver biopsy. The aim of this study is to determine the usefulness of small-diameter (2 mm) laparoscopes compared with larger laparoscopes.

METHODS

Patients undergoing diagnostic laparoscopy for various liver diseases were evaluated with small-diameter (2 mm) laparoscopes either alone or in combination with a 5 or 10 mm laparoscope.

RESULTS

Twenty patients were enrolled in this study. Small-diameter laparoscopes provided appropriate visualization of the abdominal organs and proper guidance to liver biopsy in 9 cases. In the remaining 11 cases a larger laparoscope was used for the following reasons: short length of the trocar/introducer in a morbidly obese patient (1), liver mass located in the anterosuperior aspect of the liver precluding good visualization with forward lenses (1), and inability to properly visualize the anterosuperior aspect of the liver (9). No complications were noted with the use of the small-diameter laparoscopes alone.

CONCLUSION

There is a need for an oblique-viewing minilaparoscope that allows visualization comparable to the larger laparoscopes.

Diagnostic tools in the evaluation of patients with viral hepatitis undergoing liver transplantation

Familiarity with the diagnostic parameters of viral hepatitis is imperative in the liver transplantation arena. Chronic viral hepatitis B and C are among the most common categories of end-stage liver disease. The preoperative diagnosis, determination of recurrent infection, and the assessment of antiviral therapeutic efficacy are dependent on appropriate virological testing. Furthermore, liver transplant personnel are at a high risk for parenterally transmitted viral hepatitis infection. Knowledge and understanding of the serological patterns of acute and chronic viral hepatitis, as well as recognition of the immune status for one or more of these viruses, will facilitate prevention and treatment of viral hepatitis for these health care providers.

Application of imaging-grazing-incidence X-ray diffraction and specular reflectivity to the structural investigation of quantum-confinement semiconductor devices

X-ray reflectivity and grazing-incidence X-ray diffraction techniques have been employed to investigate the structure of quantum-well and quantum-dot semiconductor devices. This work has been performed using both laboratory and synchrotron radiation sources. The use of synchrotron radiation enabled reflectivity studies to be performed on small samples, and established the feasibility of imaging-grazing-incidence diffraction studies on quantum-confinement structures. Interdiffusion effects in quantum-well and quantum-dot structures, the disordering of overlayers grown on quantum dots, and the variation in diffraction pattern with incident angle have been observed. It is evident that X-ray reflectivity and imaging-grazing-incidence X-ray diffraction yield quite different but complementary information.

Cryptic speciation in Lutzomyia (Nyssomyia) trapidoi (Fairchild & Hertig) (Diptera: Psychodidae) detected by multilocus enzyme electrophoresis

Lutzomyia trapidoi is the major vector of cutaneous leishmaniasis in Ecuador. In the framework of an epidemiologic study, female Lu. trapidoi sand flies were captured on human bait in La Tablada and Paraiso Escondido. Some coloration heterogeneity among the specimens caught led us to look for the existence of cryptic species using multilocus enzyme electrophoresis. In 196 specimens studied, five of seven enzyme loci proved to be variable, making it possible to check for departures from panmixia both by Hardy-Weinberg statistics and linkage disequilibrium analysis. Two discrete groups were clearly distinguished, which could be differentiated by the diagnostic locus glycerophosphate dehydrogenase. The two groups occurred in sympatry within each locality. Genetic distances measured between these two groups were consistent with values usually found between distinct species. These results suggest the existence of a least two sibling species in Paraiso Escondido as well as La Tablada. The epidemiologic relevance of these results is discussed.

Spatially Resolved Visible Luminescence of Self-Assembled Semiconductor Quantum Dots

Ensembles of defect-free InAIAs islands of ultrasmall dimensions embedded in AIGaAs have been grown by molecular beam epitaxy. Cathodoluminescence was used to directly image the spatial distribution of the quantum dots by mapping their luminescence and to spectrally resolve very sharp peaks from small groups of dots, thus providing experimental verification for the discrete density of states in a zero-dimensional quantum structure. Visible luminescence is produced by different nominal compositions of InxAI(1-x)As-AIyGa(1-y)As.

[Leishmaniasis in Ecuador. 3. Lutzomyia trapidoi, vector of Leishmania panamensis]

Lutzomyia trapidoi, the more abundant anthropophilic species, is a presumed leishmaniasis vector in the Pacific foothills of Ecuador. Three biotopes have been sampled (dwelling, and nearby coffee crop and primary forest) in the focus of Paraiso Escondido, by human bait catches, from August 1991 to October 1992. A large number of sandflies, 6,965 specimens, have been dissected to estimate peri and hypopyloric infections. All the peripyloric infections, characterized by isoenzyme electrophoresis, were Leishmania panamensis. The percentage of these infections was low, around 3%, but they were massive. They occurred only in dry season. Hypopyloric infections were observed in Lu. trapidoi all the year round in the three biotopes. Their percentage was high, reaching 40%. Despite of many trials to cultivate the parasite on NNN medium, no stain could be isolated. It is suggested that the parasite could be L. equatorensis.

[Leishmaniasis in Ecuador. 5. Leishmaniasis and anthropization on the Pacific coast]

We have evaluated the impact of anthropization of the forest on the incidence of leishmaniasis, due to Leishmania panamensis, in three coastal study areas, Corriente Grande (primary forest), Paraiso Escondido and La Tablada (secondary forest). The situation of isolated dwellings, in deforested areas, has also been analysed in the last two stations. In each station, the study of the density of anthropophilic sand flies, specially Lutzomyia trapidoi, has been conducted in the domestic environment, coffee plantations and undergrowth. The incidence of leishmaniasis was nearly non existent in primary forest, though it ranged from 106 to 147% in the more or less cleared forest. At Corriente Grande, none Lu. trapidoi was caught in houses. In the undergrowth, catches were low (8% of the total). At Paraiso Escondido, Lu. trapidoi was the dominant species, with more than 83% of the catches in the undergrowth and in the coffee plantations (41 Man/hour), as well as in dwellings (10.6 M/h). At La Tablada, in the domestic environment, Lu. gomezi, was the dominant species: 2.8 M/h against 0.1 M/h for Lu. trapidoi. In the coffee plantations and in the undergrowth Lu. trapidoi was the main species, 21 M/h and 14 M/h. Thus in the primary rainforest, leishmaniasis transmission can be very low. In disturbed forest, coffee plantations near houses are good biotopes for Lu. trapidoi. The cycle of L. panamensis has been adapted to this new ecological situation, by being closer to the houses. The reservoirs live and circulate throughout coffee plantations. In deforested areas, neither aggressive sand flies have been observed, nor leishmaniasis transmission.

[Leishmaniasis in Ecuador. 1. Incidence of cutaneous leishmaniasis on the Pacific coast]

A clinico-epidemiologic survey on cutaneous leishmaniasis, due to Leishmania panamensis, was carried out on 961 persons in two study areas of the Pacific coast of Ecuador, to estimate the prevalence and the incidence of the disease. In the preandean hills, at Paraiso Escondido, the prevalence of active lesions was 4.8%; in the hills of the coastal cordillera, at La Tablada, it was 3.6%. The incidence of new cases in 1991 was high: 147% in the first village, and 106% in the second. These data are far higher than the Health Ministry statistics. The cumulated prevalence, obtained by addition of the scars and active lesions of leishmaniasis, was as high as 66% at Paraiso Escondido, and 47% at La Tablada. Most of the patients (62%) had only one ulcer or scar. Most of the people are contaminated during the first five years they live in these endemic areas. Nevertheless, the incidence remains high in all the age groups, because large numbers of migrants coming from non endemic regions are continuously settling in these colonization areas. Interviews have shown that the contaminations had occurred in the dry season, between July and December. These findings were confirmed by passive case detection at the Hospital A. Egas of Santo Domingo which covered the region. Contamination of young children and position of the lesions on the face suggested a domiciliary transmission, like in Panama and on the Pacific coast of Colombia.

[Leishmaniasis in Ecuador. 2. Man/vector contacts in leishmaniasis: the case of Lutzomyia trapidoi and Lu. Gomezi]

In two leishmaniasis endemic foci of the Pacific coast of Ecuador, where the primary forest is severely attacked by human settlements, intradomiciliary sandfly catches, with light trap and human bait, have been carried out from August 1991 to October 1992. The presumed vector Lutzomyia trapidoi was by far the dominant species inside dwellings at Paraiso Escondido in the preandean hills (86% of the anthropophilic sandfly population, and 8.5 females/night catch by light trap). Not a single Lu. gomezi was caught in this village. At La Tablada, Lu. gomezi was the dominant anthropophilic species in the coastal cordillera (83% of anthropophilic sandfly population and 3.7 females/night catch by light trap); Lu. trapidoi accounted only for 4.6% of the total catches in this village. On human bait, catches were variable depending on the day and on the season, but dominant species were always the same. The percentage of Lu. trapidoi was higher on human bait than in light trap. Blood meal identifications of engorged Lu. gomezi and Lu. trapidoi confirmed the anthropophily of these two species in the houses.

A new and versatile reagent for incorporating multiple primary aliphatic amines into synthetic oligonucleotides

A novel and versatile phosphoramidite, N-Fmoc-O1-DMT-O2-cyanoethoxydiisopropylamino-phosphinyl-3-am ino-1,2-propanediol (1, Fig. 1), has been synthesized and used to incorporate primary aliphatic amines into synthetic oligonucleotides. Its convenient preparation and use in solid phase oligonucleotide synthesis is described. Using phosphoramidite 1, an amino-modified oligonucleotide probe complementary to M13mp18 DNA was constructed with five primary amines attached to the 5'-terminus. The amino-modified oligonucleotide was subsequently labeled with biotin and employed in a dot-blot hybridization assay. As little as 0.5 ng of M13mp18 target DNA was colorimetrically detected.

Two-dimensional echocardiographic features of sewing ring dehiscence of a bioprosthetic mitral valve

Images

Report on a focus of onchocerciasis in Esmeraldas province of Ecuador

A case suggesting the occurrence of onchocerciasis in Ecuador was first reported in 1952. The appearance of another case in 1977 provided the stimulus to do an epidemiologic survey on an isolated 20-km section of the Cayapa River in Esmeraldas Province. The Mazzotti test, skin biopsy, and nodulectomy were performed on 300 inhabitants of the area. Of the 300 who were tested, 210 (70%) reacted positively to the Mazzotti test, only 20 of whom had a negative skin biopsy. An additional 10 patients with a negative Mazzotti test had a positive skin biopsy. Combining the results of the Mazzotti test and skin biopsy show a 73% prevalence of onchocerciasis. Sixty-four patients (21%) had nodules, and evidence suggests that ocular pathology may be present.

Impulsivity, temporal perspective, and posthospital adjustment of neuropsychiatric patients

Hypotheses were tested regarding relationships between impulsivity as a personality construct and various biographical characteristics among neuropsychiatric patients referred for rehabilitation. Seventy-five males and five females (mean age 33) with mixed diagnoses served as Ss. Variables included an ego-delay measure obtained from temporal estimations, perceptions of temporal dominance and relatedness obtained from Cottle's Circles Test, Ss' ages, and a measure of long-term posthospital adjustment. Ego-delaying patients were significantly younger, diminished the importance of their past temporal mode relative to the present and future, perceived the future as a dominant temporal mode relative to the present and past, and achieved significantly better long-term adjustment following psychiatric hospitalization.

Some observations on the in vivo effect of propranolol on platelet aggregation and release

Platelet function was investigated in four normal volunteers, one patient with a mild form of von Willebrand disease, and one with a thrombocytopathy, all taking propranolol. No effect on platelet function attributable to this drug could be demonstrated in any of these subjects. It is suggested that propranolol administered in conventional doses does not impair platelet hemostatic function.