The larval midgut of Anopheles, Aedes, and Toxorhynchites mosquitoes (Diptera, Culicidae): a comparative approach in morphophysiology and evolution

The mosquito larval midgut is responsible for acquiring and storing most of the nutrients that will sustain the events of metamorphosis and the insect's adult life. Despite its importance, the basic biology of this larval organ is poorly understood. To help fill this gap, we carried out a comparative morphophysiological investigation of three larval midgut regions (gastric caeca, anterior midgut, and posterior midgut) of phylogenetically distant mosquitoes: Anopheles gambiae (Anopheles albimanus was occasionally used as an alternate), Aedes aegypti, and Toxorhynchites theobaldi. Larvae of Toxorhynchites mosquitoes are predacious, in contrast to the other two species, that are detritivorous. In this work, we show that the larval gut of the three species shares basic histological characteristics, but differ in other aspects. The lipid and carbohydrate metabolism of the An. gambiae larval midgut is different compared with that of Ae. aegypti and Tx. theobaldi. The gastric caecum is the most variable region, with differences probably related to the chemical composition of the diet. The peritrophic matrix is morphologically similar in the three species, and processes involved in the post-embryonic development of the organ, such as cell differentiation and proliferation, were also similar. FMRF-positive enteroendocrine cells are grouped in the posterior midgut of Tx. theobaldi, but individualized in An. gambiae and Ae. aegypti. We hypothesize that Tx. theobaldi larval predation is an ancestral condition in mosquito evolution.

The impact of early-life exposure to three agrochemicals on survival, behavior, and gut microbiota of stingless bees (Partamona helleri)

Over the last few decades, agrochemicals have been partially associated with a global reduction in bees' population. Toxicological assessment is therefore crucial for understanding the overall agrochemical risks to stingless bees. Therefore, the lethal and sublethal effects of agrochemicals commonly used in crops (copper sulfate, glyphosate, and spinosad) on the behavior and gut microbiota of the stingless bee, Partamona helleri, were assessed using chronic exposure during the larval stage. When used at the field-recommended rates, both copper sulfate (200 µg of active ingredient/bee; a.i µg bee^-1) and spinosad (8.16 a.i µg bee^-1) caused a decrease in bee survival, while glyphosate (148 a.i µg bee^-1) did not show any significant effects. No significant adverse effects on bee development were observed in any treatment with CuSO₄ or glyphosate, but spinosad (0.08 or 0.03 a.i µg bee ^-1) increased the number of deformed bees and reduced their body mass. Agrochemicals changed the behavior of bees and composition of the gut microbiota of adult bees, and metals such as copper accumulated in the bees' bodies. The response of bees to agrochemicals depends on the class or dose of the ingested compound. In vitro rearing of stingless bees' larvae is a useful tool to elucidate the sublethal effects of agrochemicals.

Intoxication by Ipomoea sericophylla and Ipomoea riedelii in goats in the state of Paraíba, Northeastern Brazil

A disease of the nervous system was observed in goats from two farms of the semiarid of the state of Paraíba, northeastern Brazil. Ipomoea sericophylla was found in one farm and I. riedelii in the other. Both plants were administered experimentally to five goats each. Both plants induced clinical signs similar to those observed in spontaneous cases. Two goats died spontaneously and five were euthanatized. Three goats recovered after the withdrawal of the plants. Histological examination showed that all goats that died spontaneously or were euthanized had diffuse vacuolation of neurons, macrophages of lymphatic tissues, and epithelial cells of pancreas, thyroid, renal tubules and liver. On electron microscopy of Purkinje cells, numerous dilated membrane bordered vacuoles were identified as lysosomes. On lectin-histochemical analysis, cerebellar cells gave positive reactions to Concanavalia ensiformis, Triticum vulgaris, and succinylated-T. vulgaris, which indicate the storage of alpha-D-mannose, alpha-D-glucose, beta-D-N-acetyl-glucosamine, and acetyl-neuraminic acid. The chemical analysis of I. sericophylla and I. riedelii showed 0.11 and 0.14% of swainsonine, respectively. The latter also contained calystegines B1, B2 and C1. It is concluded that I. sericophylla and I. riedelli cause a lysosomal storage disease.

Tremorgenic syndrome in goats caused by Ipomoea asarifolia in Northeastern Brazil

Green leaves of Ipomoea asarifolia were dosed to 10 goats. Nine goats ingesting 5-37 g/kg bw daily had clinical signs in 4-38 days. One goat ingesting 2.5 g/kg bw daily during 125 days and two control goats had no clinical signs. Clinical signs were characteristic for a tremorgenic syndrome. Five goats recovered in 4-9 days after the withdrawal of the plant. Two goats died spontaneously and three were euthanased for histologic and ultrastructural studies. No significant lesions were observed at necropsies or on the histologic and ultrastructural studies. Samples of the plant analyzed for enzymatic inhibitors were negative for calystegines and contained an almost undetectable amount of swainsonine (less than 0.001%). It is concluded that I. asarifolia causes a tremorgenic syndrome due to an unknown tremorgenic phytotoxins or mycotoxins.

Intoxication of goats by Plumbago scandens in Northeastern Brazil

In the State of Paraiba, Northeastern Brazil, goat mortality occurred with the ingestion of Plumbago scandens. The fresh plant was then given experimentally to 4 goats at 5, 10, 17.5 or 25 g/kg bw. Depression, anorexia, salivation with foamy saliva, bellowing, bruxism, humpbacked posture, bloat, ruminal atony, continuous lateral head movements, tachycardia, dyspnea and dark brown to black urine were observed in the goats given 17.5 or 25 g/kg bw. The goats receiving 5 or 10 g/kg bw had less severe signs. The goat dosed with 25 g/kg bw died after 18-20 h. All others recovered in 3-9 d. At necropsy of the high dose goat, the main lesions were dark violet to black discoloration of the mucosa of the tongue, esophagus, reticulum and ventral sac of the rumen, and gelatinous edema in the visceral ruminal peritoneum. Histologically the reticulum and ventral rumen sac had diffuse epithelial necrosis and severe edema and neutrophilic infiltration of the submucosa. Separation of the ruminal epithelium from the submucosa was observed. Epithelial degeneration and necrosis was also seen in the omasum, esophagus and tongue. Reproduction of the disease with clinical signs similar to those observed by the farmer in the spontaneously affected goats suggests that the clinical mortality was caused by ingestion of Plumbago scandens.

Electrical behavior of T-wave polarity alternans in patients with congenital long QT syndrome

OBJECTIVES

This study was designed to evaluate the incidence and characteristics of onset of T-wave polarity alternans (TWPA) in patients with long QT syndrome.

BACKGROUND

The T-wave alternans is a phenomenon that consists of beat-to-beat variability in the amplitude, morphology, and sometimes polarity of the T-wave, and it may trigger life-threatening arrhythmias.

METHODS

The 24-h Holter recordings of 11 patients with congenital long QT syndrome were studied. Episodes of TWPA with 10 or more consecutive cycles were selected and analyzed as follows: 1) mean cycle length (MCL) and QTc interval duration (QTcI) of the episodes of TWPA and the 10 cycles preceding and succeeding the TWPA; 2) MCL and QTcI of the third, second, and first minute before onset (Mn_3, Mn_2, Mn_1); 3) MCL and QTcI from the tenth to the first cycle immediately preceding the onset of TWPA (R_10 to R_1); 4) MCL and QTcI from the first to the fourteenth cycle during alternans (R0 to R14); 5) MCL and QTcI from the first to the tenth cycle immediately succeeding TWPA (R+1 to R+10); 6) linear correlation (Lnc) between QT interval and cycle length (CL) (LncQT/CL) during alternans and for the 10 preceding cycles; 7) Lnc between the first three alternans cycles and episode duration (Lnc 3CL/EpD); and 8) difference between the longest and shortest QTc interval. We also selected episodes consisting of four or more consecutive cycles in order to analyze daily rhythms of the phenomenon.

RESULTS

The TWPA was observed in 5 (45%) out of the 11 patients studied. The alternans process is initiated by a sudden shortening of the first alternans cycle without previous heart rate changes and ends at the moment when prolongation of the cycle tends to occur. LncQT/ CL-alternans: r = 0.38 +/- 0.2 (p = 0.20); without alternans: r = 0.81 +/- 0.06 (p = 0.01). Lnc 3CL/EpD: r = 0.002 (p = 0.992). The QTc difference during alternans: 312.0 +/- 52.1 ms; without alternans: 86.0 +/- 36.4 ms (p = 0.001). Daily rhythm: 71% of the episodes occurred between 8 AM and 8 PM, with higher incidence during the morning.

CONCLUSIONS

The TWPA was dependent on the cardiac CL; there was loss of the LncQT/CL and an increase in the QT interval variability. Like other biological variables, T-wave polarity alternans has a higher density during the morning.

[Contribution of dynamic electrocardiography by Holter monitoring in the evaluation of congenital long QT syndrome patients]

PURPOSE

The purpose of this study was to evaluate the value of ambulatory electrocardiogram as a clinical tool to assess ventricular repolarization in patients with the congenital long QT syndrome.

METHODS

The study population comprised six patients and their data were compared to a control group of six patients matched in age and gender. The QT interval (ms), corrected by the heart rate, was measured in the first minute of each hour using two monitoring leads, with the mean of six consecutive complexes. The data obtained include the morphologic pattern of T wave, the mean 24-h QTc interval, relation between QT and cardiac cycle, QTc variability (assessed calculating hourly standard deviation of the interval and then obtaining the global 24-h mean), QTc dispersion (difference between the longest and shortest QTc interval).

RESULTS

In all patients abnormal patterns of T waves were detected with frequent episodes of T wave alternans. Mean 24-h QTc--patients: 598.2 +/- 73.8 ms; controls: 436.1 +/- 8.9 ms (p = 0.000). Linear correlation and regression between QT and heart rate-patients: r = 0.812; controls: r = 0.967 (p = 0.000). QTc variability-patients: 36.9 +/- 17.2 ms; controls: 14.7 +/- 2.1 ms (p = 0.01). QTc dispersion-patients: 168.3 +/- 70.2 ms; controls: 53.3 +/- 8.1 ms (p = 0.000).

CONCLUSION

The data showed increased hourly QTc variability. QTc dispersion and worse correlation between QT and heart rate. This data may reflect an abnormally augmented ventricular vulnerability.

Generation of monoclonal antibodies against surface antigens of Moraxella bovis

Six hybridoma lines producing monoclonal antibodies (MAbs) against Moraxella bovis were established from fusions between the SP2/0 myeloma cells and BALB/c mice splenocytes. Three antibodies were of the IgG1 isotype, two were IgG2a, and one was IgG2b. The specificity of the antibodies was determined by indirect enzyme-linked immunosorbent assay (ELISA) using whole cells of M. bovis and of other Gram-negative bacteria, and lipopolysaccharide (LPS) from M. bovis JUR2 and E. coli as antigens. Ascitic fluid produced by the six hybridoma lines inhibited hemagglutination by M. bovis GF9. One MAb (35F) reacted specifically with purified M. bovis LPS in the ELISA test. The MAb panel detected heterogeneity among the isolates recovered from different geographical regions.

[Angioplasty of distal aorta and iliac, femoral, popliteal, renal and subclavian arteries. Early and late results]

PURPOSE

To study the late results of peripheral angioplasty.

PATIENTS AND METHODS

In the period of 8 years from August, 1981 until August, 1989, 27 patients were submitted to 33 procedures of peripheral angioplasty.

RESULTS

There was success in 29 procedures, an insufficient dilatation in 1 and and failure in 3 (2 new attempts were effective). Success rate was 88% of the procedures; clinical and angiographic success was reached in 25 (93%) of the 27 patients. Thirty four obstructions were successful dilated: 12 in renal artery, 12 in common iliac artery, 4 in external iliac artery, 3 in superficial femoral artery, 1 in distal aorta. In the evolution we had a restenosis of a renal artery that was redilated, a precocious occlusion of a common iliac artery (9% of common iliac artery dilatations and 6% of the total of the iliac dilatations) and a popliteal occlusion. Of the 34 dilatations we had a patency of 91% until 2 months.

CONCLUSION

Angioplasty showed to be an effective method with good results in the long term follow-up.