RESUMO
Lipophorin (Lp) is a major insect lipoprotein and is responsible for lipid transport between organs. In this study, the effect of starvation on Lp properties was analyzed in larval Manduca sexta during the fifth instar. Lp hemolymph concentrations in larvae at days 1 and 2 were around 2-3 mg/ml and at day 3 it increased to 8 mg/ml. When larvae were starved for 24 h, they did not grow, but their body mass and hemolymph volume did not decrease significantly. Differences in Lp densities were observed. In fed larvae, from days 1 to 4, two major Lp populations were found with densities of 1.124 ± 0.002 (high density Lp-larval1 , HDLp-L1 ) and 1.141 ± 0.002 g/ml (HDLp-L2 ). When larvae were starved for 24 h, only one Lp population was present, with density 1.114 ± 0.001 g/ml (HDLp-Ls ). When larvae were abdominally ligated at day 1 or 2 of fifth instar, only HDLp-Ls was found after 24 h, indicating that the formation of this HDLp population was not dependent on any factor released by head. On the other hand, larvae that were ligated at day 3 showed the same Lp populations as the fed ones. In 24-h starved larvae, lipid load in Lp was higher as compared to the fed controls. In 24-h ligated larvae Lp lipid content increased when ligation was performed on day 1 or 2, but not on day 3. So, different responses to starvation can be observed depending on the developmental phase of the same larval instar.
Assuntos
Hemolinfa/metabolismo , Larva/metabolismo , Lipoproteínas/sangue , Manduca/metabolismo , Animais , Transporte Biológico , Ensaio de Imunoadsorção Enzimática , Comportamento Alimentar , Privação de Alimentos , Larva/crescimento & desenvolvimento , Manduca/crescimento & desenvolvimentoRESUMO
OBJECTIVE: The study was designed to evaluate the effectiveness of SP-303 (Provir), a plant-derived product with novel antisecretory properties, in the treatment of travelers' diarrhea. METHODS: A total of 184 persons from the United States who acquired diarrhea in Jamaica or Mexico were enrolled in a double-blind, placebo-controlled study examining the effectiveness of three doses of SP-303 in reducing illness. Subjects were treated with 125 mg, 250 mg, or 500 mg SP-303 or a matching placebo four times a day for 2 days. Subjects kept daily diaries of symptoms and were seen each day for 3 days. Of the subjects, 169 (92%) were included in the efficacy analysis. RESULTS: The most common etiological agent identified was enterotoxigenic Escherichia coli, found in 19% of subjects. The mean time interval from taking the first dose of medication until passage of the last unformed stool during 48 h therapy (TLUS48) was 38.7 h for the placebo group. TLUS48 was shortened by SP-303: 30.6 h for the 125-mg dose group (p = 0.005); 30.3 h for the 250-mg group; and 32.6 h for the 500-mg group (p = 0.01). Treatment failures were seen in 29.3% in the placebo group compared with 7.3% (p = 0.01), 4.3 (p = 0.002), and 9.8 (p = 0.026) in the three treatment groups. SP-303 was well tolerated at all doses. CONCLUSIONS: SP-303 was effective in shortening the duration of travelers' diarrhea by 21%. This antisecretory approach works directly against the pathophysiology of travelers' diarrhea and is not likely to potentiate invasive forms of diarrhea or to produce posttreatment constipation.