Intestinal growth and pathology of Giardia duodenalis assemblage subtype A(I), A(II), B and E in the gerbil model.

This study investigated the significance of the genetic differences between assemblages A, B and E on intestinal growth and virulence. Intestinal growth and virulence were studied in 2 laboratory (A(I): WB and B: GS/M-83-H7) and 6 field isolates of assemblage subtype A(I), A(II), B and E(III). Intestinal trophozoite burdens, body weight and faecal consistency were monitored until day 29 post-infection (p.i.), morphological (mucosal architecture and inflammation) and functional (disaccharidase and alkaline phosphatase enzyme activity) damage to the small intestine were evaluated on days 7 and 18 p.i. The assemblage subtypes A(I) and B were more infectious and produced higher trophozoite loads for a longer period compared to the subtypes A(II) and E(III). The body weight of infected gerbils was significantly reduced compared to uninfected controls, but did not differ between the assemblage subtypes. Consistent softening of the faeces was only observed with assemblage B. Assemblage B next to assemblage subtype A(I) elicited relatively higher pathogenicity, characterized by more extensive damage to mucosal architecture, decreased brush-border enzyme function and infiltration of inflammatory cells. Assemblage E(III) and A(II) isolates showed relatively low virulence. The Giardia assemblage subtypes exhibit different levels of growth and virulence in the gerbil model.

Variation in growth and drug susceptibility among Giardia duodenalis assemblages A, B and E in axenic in vitro culture and in the gerbil model.

This study investigated the molecular and biological variation among different Giardia duodenalis assemblages. In vitro growth and susceptibility to albendazole, fenbendazole, flubendazole, metronidazole, tinidazole and furazolidone was studied for laboratory (AI: WB, AII: G1 and B: GS/M-83-H7) and 6 field isolates of assemblage subtype AI, AII, B and EIII. Additionally, isolates of the 3 assemblages were evaluated in the gerbil upon 3-day oral treatment with albendazole (6 mg/kg), flubendazole (5 mg/kg) and metronidazole (20 mg/kg). Assemblage AI grew significantly faster than all other assemblage subtypes, which showed comparable generation times. The assemblage A laboratory strains displayed altered in vitro drug susceptibilities compared to their matching AI or AII field isolate. No variation in drug susceptibility was observed between field isolates of assemblages A and E. However, assemblage A laboratory strains were more susceptible to the benzimidazoles and less susceptible to the nitro-imidazoles and furazolidone than the assemblage B laboratory strain. In the gerbil, no markedly different drug susceptibilities were observed. In conclusion, the Giardia assemblage subtype can be associated with differences in growth characteristics rather than in drug susceptibility.

Antimicrobial evaluation of the polyisoprenylated benzophenones nemorosone and guttiferone A.

Polyisoprenylated benzophenones have been isolated from plants, particularly in the Clusiaceae family, and their biological properties recently have received considerable attention from a pharmacological point of view. The aim of the study was to investigate the polyisoprenylated benzophenones, nemorosone and guttiferone A, for their antimicrobial effect against a panel of bacteria, fungi and protozoan parasites. They showed a moderate activity against the Gram-positive bacterium Staphylococcus aureus, while no activity was demonstrated against Escherichia coli and the fungi Trichophyton rubrum and Candida albicans. An interesting activity was found for Plasmodium falciparum with IC50 values lower than 1 µm, while cytotoxicity on MRC-5 cells revealed CC50 values of 15.5 and 12.0 µm, respectively, for nemorosone and guttiferone A.

Paraoxonase 1 gene transfer lowers vascular oxidative stress and improves vasomotor function in apolipoprotein E-deficient mice with pre-existing atherosclerosis.

BACKGROUND AND PURPOSE: Transgenesis of human paraoxonase 1 (PON1), a HDL-associated enzyme that destroys lipid peroxides, has been reported to reduce early atherogenesis in mice. The present study explored the therapeutic potential of human PON1 gene transfer in old apolipoprotein E-deficient (apoE(-/-)) mice with advanced atherosclerosis. EXPERIMENTAL APPROACH: ApoE(-/-) mice (18 months, regular chow) were transfected with PON1 adenovirus (AdPON1, n=10) or control adenovirus (AdRR5, n=10). Non-transfected apoE(-/-) (n=9) and C57Bl/6J (WT, n=6) mice served as controls. Three weeks later, plaque size and composition, and endothelial cell (EC) and smooth muscle cell (SMC) function were assessed in the aorta. KEY RESULTS: PON1 gene transfer raised total PON1 serum activity 13-15 fold during the 3-week study period, without affecting hypercholesterolaemia or lesion size. However, PON1 decreased the oxLDL content of the plaque. Plaque-free thoracic aorta rings from apoE(-/-) mice displayed, like rings from WT mice, complete relaxation to acetylcholine (ACh, 86+/-2%), ATP (90+/-2%) or UTP (83+/-3%). In contrast, in plaque-bearing segments amplitude (55+/-7%, 68+/-8%, 52+/-8% respectively) and sensitivity were decreased. EC function was completely (ATP, UTP) or largely (ACh) restored by AdPON1. Furthermore, apoE(-/-) SMCs released less intracellular calcium than WT upon sarco-endoplasmic reticulum calcium ATPase (SERCA) inhibition by cyclopiazonic acid. This defect was also restored by AdPON1 transfection. CONCLUSIONS AND IMPLICATIONS: These data indicate that AdPON1 gene transfer improved vascular wall oxidative stress, EC function, and SMC Ca(2+) homeostasis in segments with pre-existing atherosclerosis, independently of an effect on plaque size.

Altered Ca2+ handling of smooth muscle cells in aorta of apolipoprotein E-deficient mice before development of atherosclerotic lesions.

To study the effect of hypercholesterolemia on vascular smooth muscle cell (VSMC) function, atherosclerosis-prone but plaque-free endothelium-denuded aortic rings (width 2mm) from C57Bl6 Wild Type (WT) and apolipoprotein E-deficient (apoE(-/-)) mice (age 4 months) were mounted in a myograph and loaded with Fura-2 AM to simultaneously measure free Ca(2+) ([Ca(2+)](i)) and force development. In comparison with WT, apoE(-/-) mice displayed higher basal [Ca(2+)](i). Moreover, the time constant of the second phase of the biphasic high K(+)-induced [Ca(2+)](i) response was significantly increased in apoE(-/-) compared to WT mice. This phase was abolished by treatment with cyclopiazonic acid (CPA), depleting sarcoplasmic reticulum (SR). Further investigation of SR dependent [Ca(2+)](i) handling with CPA and caffeine revealed no alteration of maximal SERCA or ryanodine receptor function. Inositol (1,4,5)-triphosphate receptor (IP(3)R)-mediated [Ca(2+)](i) release was, however, significantly increased in apoE(-/-) mice compared to WT mice as established with phenylephrine and ATP. In Ca(2+)-free conditions the ATP-induced [Ca(2+)](i) was not altered. The ATP-induced store-operated Ca(2+) entry was, however, significantly increased in apoE(-/-) compared to WT mice. The results demonstrate that basal [Ca(2+)](i) levels and IP(3)R-mediated store-operated [Ca(2+)](i) release over the plasma membrane were elevated in hypercholesterolemic but plaque-free apoE(-/-) mice.