Relapses of Plasmodium vivax infection usually result from activation of heterologous hypnozoites.

BACKGROUND: Relapses originating from hypnozoites are characteristic of Plasmodium vivax infections. Thus, reappearance of parasitemia after treatment can result from relapse, recrudescence, or reinfection. It has been assumed that parasites causing relapse would be a subset of the parasites that caused the primary infection. METHODS: Paired samples were collected before initiation of antimalarial treatment and at recurrence of parasitemia from 149 patients with vivax malaria in Thailand (n=36), where reinfection could be excluded, and during field studies in Myanmar (n=75) and India (n=38). RESULTS: Combined genetic data from 2 genotyping approaches showed that novel P. vivax populations were present in the majority of patients with recurrent infection (107 [72%] of 149 patients overall [78% of patients in Thailand, 75% of patients in Myanmar {Burma}, and 63% of patients in India]). In 61% of the Thai and Burmese patients and in 55% of the Indian patients, the recurrent infections contained none of the parasite genotypes that caused the acute infection. CONCLUSIONS: The P. vivax populations emerging from hypnozoites commonly differ from the populations that caused the acute episode. Activation of heterologous hypnozoite populations is the most common cause of first relapse in patients with vivax malaria

Anti-Guest Statutes and Marital Immunity for Torts in Conflict of Laws: Techniques for Resolving Ostensible True Conflict Cases and Constitutional Limitations

In the now historic case of Babcock v. Jackson, decided in 1963, the New York Court of Appeals introduced an apparently novel mode of analyzing tort choice-of-law issues that has achieved remarkable popularity with the judges of other states. It has been adopted in tort cases where the facts and issues were quite different from those of Babcock v. Jackson and in contract cases as well. Why does the Babcock v. Jackson methodology appeal so strongly to the judges of the highest state tribunals? The short answer is that this methodology is extremely realistic; it brings the judges directly to grips with the basic elements of the choice problem: two divergent rules of law producing divergent practical results and effectuating divergent policies. Of these two rules the judges must choose one. The new methodology emancipates them from the simplistic place of injury formula with its distracting and misleading escape devices. It enables them to base their choice upon a rational consideration of the policies and effects of each of the proffered rules in relation to the domiciles of the parties and the location of other significant facts in the case

Plasmodium falciparum: inhibition/reversal of cytoadherence of Thai isolates to melanoma cells by local immune sera

The effect of sera on the cytoadherence in vitro of Plasmodium falciparum-infected erythrocytes to melanoma cells was examined. Sera from 19 healthy individuals living in endemic malarious areas in Thailand and 24 patients with P. falciparum malaria were tested against four local P. falciparum isolates. Out of 57 sera examined, 12 (21 %) showed significant inhibition (> 50%) of cytoadherence for at least one isolate. Anti-malarial IgG antibody titres were determined for all 57 sera and although 11 of the 12 inhibitory sera had relatively high titres, 36 out of47 sera with similarly high titres showed no significant inhibitory activity. Convalescent sera were no more effective than corresponding acute sera in inhibiting the cytoadherence of erythrocytes infected with any of the four heterologous isolates examined. Sera which significantly inhibited cytoadherence were also capable of reversing cytoadherence, and pooled plasma, from healthy individuals living in malarious areas, was effective in significantly reversing the in vitro cytoadherence of all the five parasite isolates examined. The results confirm the antibody mediated strain-specific nature of the inhibition of cytoadherence and stress the difficulty in selecting immune sera potentially useful for the immunotherapy of cerebral malaria patients in Thailand

Critical discussion of Daniel C. Dennett, The Intentional Stance.

Daniel Dennett spends a good bit of time defending the possibility of a compromise position on the reality of beliefs and desires. It will be claimed that a puzzle remains in the interpretation of Dennett's position. In earlier works one finds a theme, which we can call 'near-fatalism', which has not been integrated with the kind of middle ground he describes. But the near-fatalism theme is dropped in later work. Is it because it is felt to be incompatible with that middle ground compromise? It is not obviously so

Brain Swelling and Mannitol Therapy in Adult Cerebral Malaria: A Randomized Trial

Mild cerebral swelling on CT-scan was common in adult patients with cerebral malaria, but severity of swelling was not correlated with coma depth or survival. Mannitol as adjunctive treatment for cerebral malaria prolonged coma duration and may be harmful

Plasmodium chabaudi chabaudi malaria parasites can develop stable resistance to atovaquone with a mutation in the cytochrome b gene

<p>Abstract</p> <p>Background</p> <p><it>Plasmodium falciparum</it>, has developed resistance to many of the drugs in use. The recommended treatment policy is now to use drug combinations. The atovaquone-proguanil (AP) drug combination, is one of the treatment and prophylaxis options. Atovaquone (ATQ) exerts its action by inhibiting plasmodial mitochondria electron transport at the level of the cytochrome bc1 complex. <it>Plasmodium falciparum in vitro </it>resistance to ATQ has been associated with specific point mutations in the region spanning codons 271-284 of the <it>cytochrome b </it>gene. ATQ -resistant <it>Plasmodium yoelii </it>and <it>Plasmodium berghei </it>lines have been obtained and resistant lines have amino acid mutations in their CYT <it>b </it>protein sequences. <it>Plasmodium chabaudi </it>model for studying drug-responses and drug-resistance selection is a very useful rodent malaria model but no ATQ resistant parasites have been reported so far. The aim of this study was to determine the ATQ sensitivity of the <it>P. chabaudi </it>clones, to select a resistant parasite line and to perform genotypic characterization of the <it>cytb </it>gene of these clones.</p> <p>Methods</p> <p>To select for ATQ resistance, <it>Plasmodium. chabaudi chabaudi </it>clones were exposed to gradually increasing concentrations of ATQ during several consecutive passages in mice. <it>Plasmodium chabaudi cytb </it>gene was amplified and sequenced.</p> <p>Results</p> <p>ATQ resistance was selected from the clone AS-3CQ. In order to confirm whether an heritable genetic mutation underlies the response of AS-ATQ to ATQ, the stability of the drug resistance phenotype in this clone was evaluated by measuring drug responses after (i) multiple blood passages in the absence of the drug, (ii) freeze/thawing of parasites in liquid nitrogen and (iii) transmission through a mosquito host, <it>Anopheles stephensi</it>. ATQ resistance phenotype of the drug-selected parasite clone kept unaltered. Therefore, ATQ resistance in clone AS-ATQ is genetically encoded. The Minimum Curative Dose of AS-ATQ showed a six-fold increase in MCD to ATQ relative to AS-3CQ.</p> <p>Conclusions</p> <p>A mutation was found on the <it>P. chabaudi cytb </it>gene from the AS-ATQ sample a substitution at the residue Tyr268 for an Asn, this mutation is homologous to the one found in <it>P. falciparum </it>isolates resistant to ATQ.</p

Confirmation of emergence of mutations associated with atovaquone-proguanil resistance in unexposed Plasmodium falciparum isolates from Africa

BACKGROUND: In vitro and in vivo resistance of Plasmodium falciparum to atovaquone or atovaquone-proguanil hydrochloride combination has been associated to two point mutations in the parasite cytochrome b (cytb) gene (Tyr268Ser and Tyr268Asn). However, little is known about the prevalence of codon-268 mutations in natural populations of P. falciparum without previous exposure to the drug in Africa. METHODS: The prevalence of codon-268 mutations in the cytb gene of African P. falciparum isolates from Nigeria, Malawi and Senegal, where atovaquone-proguanil has not been introduced for treatment of malaria was assessed. Genotyping of the cytb gene in isolates of P. falciparum was performed by PCR-restriction fragment length polymorphism and confirmed by sequencing. RESULTS: 295 samples from Nigeria (111), Malawi (91) and Senegal (93) were successfully analyzed for detection of either mutant Tyr268Ser or Tyr268Asn. No case of Ser268 or Asn268 was detected in cytb gene of parasites from Malawi or Senegal. However, Asn268 was detected in five out of 111 (4.5%) unexposed P. falciparum isolates from Nigeria. In addition, one out of these five mutant Asn268 isolates showed an additional cytb mutation leading to a Pro266Thr substitution inside the ubiquinone reduction site. CONCLUSION: No Tyr268Ser mutation is found in cytb of P. falciparum isolates from Nigeria, Malawi or Senegal. This study reports for the first time cytb Tyr268Asn mutation in unexposed P. falciparum isolates from Nigeria. The emergence in Africa of P. falciparum isolates with cytb Tyr268Asn mutation is a matter of serious concern. Continuous monitoring of atovaquone-proguanil resistant P. falciparum in Africa is warranted for the rational use of this new antimalarial drug, especially in non-immune travelers

Malaria treatment failures after artemisinin-based therapy in three expatriates: could improved manufacturer information help to decrease the risk of treatment failure ?

BACKGROUND: Artemisinin-containing therapies are highly effective against Plasmodium falciparum malaria. Insufficient numbers of tablets and inadequate package inserts result in sub-optimal dosing and possible treatment failure. This study reports the case of three, non-immune, expatriate workers with P. falciparum acquired in Africa, who failed to respond to artemisinin-based therapy. Sub-therapeutic dosing in accordance with the manufacturers' recommendations was the probable cause. METHOD: Manufacturers information and drug content included in twenty-five artemisinin-containing specialities were reviewed. RESULTS: A substantial number of manufacturers do not follow current WHO recommendations regarding treatment duration and doses. CONCLUSION: This study shows that drug packaging and their inserts should be improved

Efficacy and tolerability of four antimalarial combinations in the treatment of uncomplicated Plasmodium falciparum malaria in Senegal

<p>Abstract</p> <p>Background</p> <p>In view of the high level of chloroquine resistance in many countries, WHO has recommended the use of combination therapy with artemisinin derivatives in the treatment of uncomplicated malaria due to <it>Plasmodium falciparum</it>. Four antimalarial drug combinations, artesunate plus amodiaquine (Arsucam^®), artesunate plus mefloquine (Artequin^®), artemether plus lumefantrine (Coartem^®; four doses and six doses), and amodiaquine plus sulphadoxine-pyrimethamine, were studied in five health districts in Senegal.</p> <p>Methods</p> <p>This is a descriptive, analytical, open, randomized study to evaluate the efficacy and tolerability of these four antimalarial combinations in the treatment of uncomplicated falciparum malaria using the 2002 WHO protocol.</p> <p>Results</p> <p>All drug combinations demonstrated good efficacy. On day 28, all combinations resulted in an excellent clinical and parasitological response rate of 100% after correction for PCR results, except for the four-dose artemether-lumefantrine regimen (96.4%). Follow-up of approximately 10% of each treatment group on day 42 demonstrated an efficacy of 100%.</p> <p>The combinations were well tolerated clinically and biologically. No unexpected side-effect was observed and all side-effects disappeared at the end of treatment. No serious side-effect requiring premature termination of treatment was observed.</p> <p>Conclusion</p> <p>The four combinations are effective and well-tolerated.</p