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Biomedical subjects

I Landau

Publications and source records attributed to I Landau.

At least 19 recordsLinked to original sources
PubMed2006

Quassia amara L. (Simaroubaceae) leaf tea: effect of the growing stage and desiccation status on the antimalarial activity of a traditional preparation.

In French Guiana, Quassia amara L. (Simaroubaceae) leaf tea is a well-known widely used traditional antimalarial remedy. Impact of the vegetal sampling condition on in vivo and in vitro antimalarial activity was assessed. Traditional infusions were prepared with juvenile or mature leaves, both either fresh or dried. Results showed that growing stage and freshness of vegetal material exert a striking effect on antimalarial activity, both in vitro and in vivo. By far, leaf tea made from fresh juvenile (FJ) Quassia amara leaves was the most active. In vitro, active component (simalikalactone D) concentration correlates biological activities, although unexplained subtle variations were observed. In vivo, tea made with dried juvenile (DJ) leaves displays a peculiar behavior, meaning that some components may help simalikalactone D delivery or may be active in vivo only, therefore enhancing the expected curative effect of the traditional preparation.

Animals↗
PubMed2005

Evaluation of French Guiana traditional antimalarial remedies.

In order to evaluate the antimalarial potential of traditional remedies used in French Guiana, 35 remedies were prepared in their traditional form and screened for blood schizonticidal activity in vitro on Plasmodium falciparum chloroquine re4sistant strain (W2). Some of these extracts were screened in vivo against Plasmodium yoelii rodent malaria. Ferriprotoporphyrin inhibition test was also performed. Four remedies, widely used among the population as preventives, were able to inhibit more than 50% of the parasite growth in vivo at around 100 mg/kg: Irlbachia alata (Gentiananceae), Picrolemma pseudocoffea (Simaroubaceae), Quassia amara (Simaroubaceae), Tinospora crispa (Menispermaceae) and Zanthoxylum rhoifolium (Rutaceae). Five remedies displayed an IC50 in vitro < 10 microg/ml: Picrolemma pseudocoffea, Pseudoxandra cuspidata (Annonaceae) and Quassia amara leaves and stem, together with a multi-ingredient recipe. Two remedies were more active than a Cinchona preparation on the ferriprotoporphyrin inhibition test: Picrolemma pseudocoffea and Quassia amara. We also showed that a traditional preventive remedy, made from Geissospermum argenteum bark macerated in rum, was able to impair the intrahepatic cycle of the parasite. For the first time, traditional remedies from French Guiana have been directly tested on malarial pharmacological assays and some have been shown to be active.

Administration, Oral↗
PubMed2005

Eimeria (Coccidia: Eimeridea) of hares in France: description of new taxa.

The oocysts of coccidian of the genus Eimeria were sought in the caecal contents of 46 Lepus granatensis and 18 L. europaeus captured in France. Parasites were found in 34 of the hares. Parasite load was mainly very low. However, species diversity was considerable. 21 species or subspecies were identified, of which 13 species and two subspecies were not previously described. Three of the taxa, E. robertsoni, E. semisculpta and E. townsendi, previously identified on numerous occasions in western Europe and, corresponding to forms or variants created before 1960 that have been subsequently elevated to a specific level, appear to be invalid. Indeed, the parasite descriptions from the material used to effect this modification do not correspond to the original descriptions. A stable equilibrium, as generally observed in the case of many congeneric species co-infection of the same host, was not observed in the hares. This has been attributed to the solitary habits of the host and of the probable polyphyletic nature of the genus Eimeria. Paleontological data for the Leporidae indicate that rabbit parasites are derived from those of the hare.

Animals↗
PubMed2004

Action of adrenalin on the circulation of the murine Plasmodium developing stages, in different blood compartments.

Adrenalin was used to investigate in vivo the circulation of the different stages of rodent Plasmodium present in the blood. A single dose of adrenalin injected to mice infected with P. yoelii resulted immediately in i) a diminution of the parasitaemia of approximately 50% in the peripheral large vessels (estimated in tail blood films), as well as in the capillaries (estimated in smears of blood collected from a fed Anopheles), and ii) an increased parasitaemia in blood collected by cardiac puncture from the right heart. The numbers of young stages of P. yoelii in the peripheral blood were initially somewhat reduced but, unexpectedly, midterm trophozoites were preferentially expelled from the peripheral blood into major organs like the heart. With P. vinckei, parasitaemia decreased only when midterm trophozoites predominated, and with P. chabaudi no effect was observed at any time. We propose that midterm trophozoites, by their increased surface area, as compared to rings, and their flexibility which contrasts with the rigid schizonts, are particularly susceptible to haemodynamic perturbations.

Animals↗
PubMed2004

The role of sildenafil in the treatment of erectile dysfunction in patients with pelvic fracture urethral disruption.

PURPOSE: Erectile dysfunction (ED) is a common sequel of pelvic fracture urethral disruption (PFUD). After repair of the urethral injury ED may be the most devastating long-term effect for the patient. Some patients with ED may regain normal erectile function. We prospectively studied the response to sildenafil and the erectile function of patients with ED due to PFUD. MATERIALS AND METHODS: The erectile function of patients referred to us with PFUD for urethroplasty were prospectively evaluated before surgery. Patients underwent nocturnal penile tumescence testing and, if results were abnormal, penile duplex ultrasonography with intracavernous injection and arteriography were performed to diagnose the etiology of ED. Patients were questioned about erectile function every 3 months after surgery and if they complained of ED they were offered 100 mg sildenafil. Patients were followed for at least 18 months after surgery. RESULTS: A total of 29 consecutive patients were evaluated and 22 (76%) of them had ED before surgery. Sufficient followup was available for 15 of the patients. Overall 47% of these patients responded favorably to sildenafil. Of the patients 60% with neurogenic ED and 20% of those with arterial ED responded to this treatment. In 33% of the patients ED resolved within the followup period. All patients with spontaneous resolution of ED previously responded to sildenafil (71% of sildenafil responders). CONCLUSIONS: In patients with ED due to PFUD, those with neurogenic ED are more likely to respond to sildenafil than those with arterial damage. Favorable response to sildenafil may predict spontaneous resumption of normal erectile function over time.

Adolescent↗
PubMed2003

Coccidiosis of the wild rabbit (Oryctolagus cuniculus) in France.

In 1998-1999 a survey of coccidiosis in wild rabbits was carried out in six different localities in France. About five individuals were caught monthly in each locality and a total of 254 wild rabbits was examined. Ten species of Coccidio were identified: Eimeria perforans, E. flavescens, E. piriformis, E. exigua, E. media, E. magna, E. coecicola, E. stiedai, E. roobroucki, E. intestinalis. Intensity of infection in young individuals was higher than in adults. Intensity was highest in winter but, as there are no young rabbits in winter, in young individuals it was higher in spring and autumn than in summer. Intensities were higher in the northern rather than in southern localities. Ranking of prevalence was remarkably stable, in contrast to the variability of the parasitic load. The equilibrium between congeneric species of rabbit coccidia (stable prevalence rank, variable parasitic load) is thought to be probably the consequence of the opportunistic feeding habits of rabbits.

Age Factors↗
PubMed2003

Taxonomic status and re-description of Plasmodium relictum (Grassi et Feletti, 1891), Plasmodium maior Raffaele, 1931, and description of P. bigueti n. sp. in sparrows.

The first accurate re-description of Plasmodium relictum (Grassi et Feletti, 1891) in its type host was provided by Raffaele in 1931, and the name relictum should thus refer to this work. In his article, Raffaele noted the presence of an associated but distinct species, P. maior. The work of Raffaele has since remained overlooked, and the taxon relictum has been applied rather loosely to parasites found in numerous birds of diverse geographic origin. Examination of Passer domesticus specimens collected in France has confirmed the presence of the two species above, and further revealed that two other species can also be found in these birds. P. bigueti n. sp. is described here, whereas the other Plasmodium sp. was not found in sufficient numbers to allow characterisation.

Animals↗
PubMed2002

Stage-specific transcription of distinct repertoires of a multigene family during Plasmodium life cycle.

Members of a multigene family in the rodent malaria parasite Plasmodium yoelii yoelii code for 235-kilodalton proteins (Py235) that are located in the merozoite apical complex, are implicated in virulence, and may determine red blood cell specificity. We show that distinct subsets of py235 genes are expressed in sporozoites and hepatic and erythrocytic stages. Antibodies to Py235 inhibited sporozoite invasion of hepatocytes. The switch in expression profile occurred immediately after transition from one stage to another. The results suggest that this differential expression is driven by strong biological requirements and provide evidence that hepatic and erythrocytic merozoites differ.

Amino Acid Sequence↗
PubMed2002

Variation in murid Plasmodium desequestration and its modulation by stress and pentoxifylline.

Changes in the parasitaemia and the characteristics of parasitic infection for three species of rodent Plasmodium (P. chabaudi chabaudi, P. vinckei petteri and P. yoelii yoelii) were investigated under conditions of stress and after treatment with pentoxifylline (POF), a drug that increases red blood cell deformability and causes peripheral vasodilatation. The results indicated that under stress, late parasite stages became less abundant in the tail blood of mice. These changes might be the consequence of parasite sequestration. Attempts to assess sequestration intensity were made by measuring the release rate (RR) of late stages for 10,000 red blood cells. The RR is given by the product of the parasitaemia (P) by the percentage of old trophozoites (OT) and schizonts (S) in the peripheral blood: RR = P(%OT + %S) . With all three species, RR decreased considerably within 5 min following the manipulation of the mice. Injections of POF had the opposite effect. POF had a protective effect against infection by P.v. petteri, causing a delay of 48 h in the development of infection and a higher survival rate in treated mice.

Animals↗
PubMed2002

Changes in schizogony and drug response in two lines of rodent Plasmodium, P. berghei NK 65 and P. berghei ANKA.

White mice were infected with two strains, ANKA and NK 65, of Plasmodium berghei. The parasites were subjected to chloroquine pressure (60 mg/kg at each passage) during 20 passages. We then compared the behaviour of the strains as they acquired chemoresistance. The drug resistance was estimated by the 2% delay time test (D2%), and the schizogonic rhythm by the synchronicity index (SI). Before drug pressure, the ANKA strain had a D2% of 4.34, and a SI of 0.2. This strain became highly drug resistant, but synchronicity increased: the D2% was 2.93, and the SI was 0.36 at the 20th passage. The NK 65 strain had an initial D2% of 4.12, and an SI of 0.2. The chemoresistance acquired during 20 passages was very irregular for this strain: after drug pressure, the D2% was 2.03 and the SI was 0.28. Drug pressure was then removed (for both strains), for 10 passages (no chloroquine). Resistance and synchronicity returned to their initial values. The two strains behaved very differently, in terms of their affinity for reticulocytes, and with chloroquine activity which favours an increase in SI because only merozoites are preserved.

Animals↗
PubMed2002

Parasitic pattern of rodent Plasmodium in blood from mouse tail and from Anopheles blood meal.

During the course of the infection of mice by rodent malaria parasites (P. yoelii yoelii, P. vinckei petteri, and P. chabaudi chabaudi) the parasitic pattern in the blood smears differed according to the site of sampling: mosquito blood meal (usually actively sucked from capillaries) or mouse tail (issued from larger vessels). There were fewer old trophozoites and mature schizonts, and more immature schizonts, in the mosquito blood meal than in the tail blood of mice. It is suggested that the erythrocyte containing a schizont becomes less rigid when merozoites formation begins. The greater abundance in the mosquito blood meal of the gametocytes infective stage (0-I for P. yoelii, II for P. vinckei), previously shown, could be due to a particular flexibility of this stage, a character progressively selected.

Animals↗
PubMed2001

Inhibition of Plasmodium yoelii blood-stage malaria by interferon alpha through the inhibition of the production of its target cell, the reticulocyte.

The effect of a recombinant hybrid human interferon alpha (IFN-alpha) (which cross-reacts with murine cells) on C57BL/6 mice infected with Plasmodium yoelii sporozoites or parasitized erythrocytes was determined. IFN-alpha did not inhibit the development of the parasite in the liver, but it did reduce the blood parasite load and the hepatosplenomegaly induced by the infection in mice injected with blood-stage parasites. The extent of anemia in IFN-alpha-treated and control mice was similar, despite the lower parasite load in the IFN-alpha-treated mice. The reduced blood parasite load in IFN-alpha-treated mice was associated with reduced erythropoiesis and reticulocytosis. As reticulocytes are the preferred target cells for the strain of P yoelii used (P yoelii yoelii 265 BY), it was postulated that the inhibition of reticulocytosis in IFN-alpha-treated mice was causally related to the observed decreased blood parasite load. This was supported by the finding that IFN-alpha inhibited a different strain of P yoelii (17X clone A), which also displays a tropism for reticulocytes, but not a line of Plasmodium vinckei petteri, which infects only mature red blood cells. As human malaria species also display different tropism for reticulocytes, these findings could be relevant for people coinfected with multiple Plasmodium species or strains or coinfected with Plasmodium and virus. (Blood. 2001;97:3966-3971)

Animals↗
PubMed2001

Ultrastructure of developmental stages of Hemolivia stellata (Apicomplexa: Haemogregarinidae) in the cane toad Bufo marinus and in its vector tick Amblyomma rotondatum.

The fine structure of the hemogregarine Hemolivia stellata Petit, Landau, Baccam and Lainson, 1990 developmental stages in the cane toad Bufo marinus L. and the vector tick Amblyomma rotondatum Koch, 1844 are described. In the liver of the toad, merozoites bound by a pellicle were located free and in the cytoplasm, and young and encased mature polynucleated meronts were located in a parasitophorous vacuole (PV). Premature gametocytes in the erythrocytes were bound by a bilayered membranous wall and the mature gametocytes were encased in a bivalved capsule, suture sites occurring at both gametocyte extremities. In the tick gut cells, oocysts located within a PV formed oblong, pellicle-bound sporokinetes, with a small apical complex, a few short rhoptries, and a fragmented crystalloid body. Liberated sporokinetes re-entered gut cells to proceed with their differentiation into sporocysts within a PV with elaborate rims which suggested engagement in active metabolite cross-transport. With maturity, the sporocyst wall gradually transformed into a hard capsule. Differences in fine structural development between species of Hemolivia and the insect-transmitted Hepatozoon are conspicuous. The fine structure and course of development of H. stellata are very similar to those of the previously described Hemolivia mariae; their sporokinetes differ, however, in having conspicuous rhoptries rather than spherical-granular anlagen bodies, and fragmented rather than continuous crystalline bodies.

Animals↗
PubMed2001

Transpupillary thermotherapy as an adjunct to ruthenium plaque radiotherapy for choroidal melanoma.

PURPOSE: To review the Swedish experience using transpupillary thermotherapy (TTT) as an adjunct to ruthenium plaque radiotherapy for choroidal melanoma. METHODS: A retrospective chart review of 27 patients receiving TTT for juxtapapillary or juxtafoveal growth present at the time of diagnosis, or recurrent growth at the tumour margin, or significant exudation following ruthenium brachytherapy for choroidal melanoma. RESULTS: Follow-up ranged from 6 to 29 months (median=20 months). Tumour growth regressed completely (n=8), regressed partially (n=11), remain unchanged (n=6) or progressed (n=2). Complications included focal lens opacity with or without associated posterior synechiae (n=3), retinal haemorrhage (n=2) and retinal vein occlusion (n=1). Seventeen patients (63%) maintained or improved visual acuity and 2 eyes were enucleated following combined treatment. CONCLUSION: Many of the treated eyes would have been enucleated in the past, suggesting that TTT used in combination with ruthenium brachytherapy improves the short term globe salvage rate. Ocular side effects do occur but are usually not significant.

Adult↗
PubMed2001

Plasmodium kentropyxi n.sp. (Apicomplexa: Haemosporina: Plasmodiidae) and a Plasmodium tropiduri-like parasite in the lizard Kentropyx calcarata (Lacertilia: Teiidae) in north Brazil.

Plasmodium kentropyxi n.sp. is described in the teiid lizard Kentropyx calcarata from north Brazil. Young asexual stages and gametocytes are at first polar in the erythrocyte but with elongation, move to a lateral position. Largest meronts seen contained from 30-40 nuclei and conspicuous greenish-black pigment granules located in a distinct vacuole. With growth the gametocytes eventually assume a smooth, curved cylindrical shape, with evenly rounded ends. Pigment is scattered or concentrated around a conspicuous vacuole which is slowly developed as the gametocytes mature. Mature male parasites measured 11.8 x 4.0 microns (9.6 x 4.2 - 13.2 x 3.6 microns), shape-index 2.9 (2.2 - 5.0), and females 13.5 x 4.5 microns (12.0 x 4.5 - 15.0 x 4.8 microns), shape-index 3.0 (2.2 - 3.8). Some larger meronts may slightly enlarge the erythrocyte, but most asexual stages and the mature gametocytes rarely do so. A second, P. tropiduri-like parasite encountered in K. calcarata possessed small rounded or fan-shaped meronts producing from 4-14 merozoites, and spherical to subspherical gametocytes of approximately 6.0 x 5.0 microns. The parasite was consistently polar in its position in the erythrocyte.

Animals↗
PubMed2001

Description and ultrastructure of Leishmania zuckermani n. sp. amastigotes detected within the erythrocytes of the South African gecko Pachydactylus turneri Gray, 1864.

In erythrocytes recovered from blood of geckoes of the species Pachydactylus turneri collected in Gauteng Province, Republic of South Africa, leishmania zuckemani n. sp. were detected. Giemsa stained erythrocytes contained amastigotes, either single or numerous, in loose assemblies or in a compact rounded oggregates which may condense to become a round basophilic bodies with a central hollow. This new species of Leishmania differs from all previously described species in being almost exclusively parasitic in circulating erythrocytes. Three to seven amastigotes lodged all within one, or divided between several parasitophorous vacuoles were detected at the EM level. The amastigotes demonstrated essentially all the cytological components characteristic of leishmania species known to parasitize mammals. A point which emphasizes an already suggested close affiliation between mammalian and lizard Leishmania.

Animals↗
PubMed2001

Short-term effect of chloroquine on the infectivity of Plasmodium chabaudi gametocytes.

The short-term enhancing effect of chloroquine on gametocyte infectivity was investigated with Plasmodium chabaudi chabaudi, a synchronous parasite which is highly sensitive to chloroquine. In comparison with control groups, oocyst numbers increased in mosquitoes fed on mice 12 hours after the injection of 5 mg/kg chloroquine (180% of controls) although it was not statistically significant. No effect was seen with 1 mg/kg chloroquine. The authors interpretation is that chloroquine impaired the schizogony, thus reducing also the release of toxic material of parasite origin which blocks gametocytes infectivity. Results of similar experiments with other rodent species of Plasmodium are compared and discussed in relation with the chronobiological characteristics of these parasites.

Animals↗