[Monitoring delagil (chloroquine) efficacy against imported Plasmodium vivax strains].

The efficiency of P. vivax malaria treatment with delagil (chloroquine) was evaluated in 122 patients, including 82 cases in Moscow and the Moscow region. The origin of the cases was malaria endemic areas in Asia, Africa, the Pacific Region, South America, and Transcaucasia. Forty other cases were imported malaria cases (secondary to imported ones), detected in Moscow and the Moscow region. Standard treatment with delagil (2.5 g) resulted in clinical improvement during 3 days in the majority of cases. Initial signs of degradation of asexual stages of P. vivax--kernels of nucleus, refinement of cytoplasm and its vacuolization, aggregation of pigment in isolated instances, its pushing out from cytoplasm--were observed after 1-2 hours after administration of delagil. Thereafter, parasite degradation was increasing, and it disappeared within 48 hours. Disappearance of fever slowed down in a few cases. However, degradation of parasites occurred during the same period among the rest of cases. It can not be excluded that fever was determined by the pyrogenic effect of remnants of degraded parasites and by the products of destroyed infected erythrocytes. It is probable that the findings of gametocytes, not completely degraded after disappearance of asexual forms in conjunction with prolonged fever, could result in a wrong conclusion of drug resistance. Negative results of microscopy and nested PCR on the last day of treatment, as well as in the following 10 days and absence of complains during 45 days, suggest the absence of resistance to delagil in P. vivax strains imported from different regions of the world. It is also probable that the literature on P. vivax resistance to chloroquine is limited to sporadic cases.

[Efficiency of KAT-quick P.f. test (KAT medical, SAR) among the populations of drug-resistant parasites].

The KAT-Quick P.f. test (KAT Medical, South African Republic) is based on the detection of protein HPR II produced by trophozoites and young gametocytes of P. falciparum. This test was conducted by the authors in the distribution areas of P. falciparum strains differing in the spectrum of drug resistance. Five hundred and forty-nine blood samples from febrile patients in Vietnam (n=84), Sierra Leone (n=41), Nigeria (n=14), Tanzania (n=8), Kenya (n=5), and Tadjikistan (n=397) were tested. Microscopy served as a primary control. Detection of P. falciparum DNA, using polymerase chain reaction (PCR) with included primers (nested PCR) of the most sensitive modification of PCR was a final control. The efficiency of the KAT-Quick P.f. test was estimated as a ratio of the number of its positive results to those of PCR. It was equal to 98-95%. The KAT-Quick P.f. test revealed no false-positive case associated with the genome of the parasite. The specificity of the test was determined as a ratio of the number of its negative (no P. falciparum) results to those of PCR. The blood samples from patients with vivax malaria and from those with nonmalarial fever were investigated. There was no cross reaction of the KAT-Quick P.f. test system for P. falciparum with that for P. vivax. The KAT-Quick P.f. test yielded no positive reaction with the blood from patients with non-malarial fever. Drug resistance depending on the spectrum of specific drugs caused its emergence may be determined by one or several mechanisms that are ultimately determined by one, the key mechanism. Thus, the findings suggest that multidrug resistance of P. falciparum does not trigger the occurrence of changes in its surface antigen--HRPII that is responsible for the efficiency of the KAT-Quick P.f. test. These may be also extrapolated to other rapid tests patterned after the same principle.

[Efficiency and specificity of the KAT-test for rapid diagnosis of falciparum malaria]. / Effektivnost' i spetsifichnost' KAT-testa pri ékspress-diagnostike tropicheskoi malarii.

A new rapid KAT Quick Malaria test for the diagnosis of falciparum malaria, which is based on the detection of a monoclonal antibody-antigen complex of malaria parasites, has been worked out by the KAT Medical CC in South Africa. The efficiency and specificity of the KAT test were compared with those of the microscopic method and with the ICT test for rapid diagnosis of P. falciparum and P. vivax. The polymerase chain reaction was used as a control test. Testing for malaria was performed on 98 blood samples from feverish patients in Vietnam and Tadjikistan and among the persons who had returned to Moscow from endemic regions. The efficiency of the KAT test for falciparum-malaria was found to be 100% versus 90.5% with ICT. The absence of cross-reactions with P. vivax and the presence of pseudopositive results of the KAT test for fever cases of non-malaria origin indicate its high specificity. There was no correlation between the rate of test line colouring and the level of parasitemia. The KAT test yielded positive results only when gametocytes were found in blood specimens.

[ITS1, 5.8S and A-type ITS2 rDNA sequences from Plasmoidum vivax and development of a method for retrospective PCR diagnosis of malaria by stained thick blood smears]. / Posledovatel'nost' ITS1, 5.8S i ITS2 rDNA A-tipa Plasmodium vivax i razrabotka metoda retrospektivnoi PTsR-diagnostiki malarii po okrashennym preparatam krovi "tolstaia kaplia".

Stages life cycle of the malaria parasite differ in the rate of replication and the structural properties of functionally active A-, S-, and O-type ribosomes. Regions of A-type rDNA including ITS1, 5.8S, and ITS2 from two strains of Plasmodium vivax with different incubation periods were amplified and sequenced. No substantial differences in the sequences of two strains were revealed. Phylogenetic analysis of the obtained and homologous sequences of ITS1 rDNA of A, S, and O types of P. vivax; A and S types of P. falciparum; and Cryptosporidium parvum, Eimeria maxima, Toxoplasma gondii as outgroup, by the maximum parsimony method using PAUP 4.0 revealed that divergence of ITS1 might have occurred after speciation and at different rates in individual lineages of the Plasmodium genus. Basing on the results of the analysis of orthologous sequences of P. vivax and P. falciparum, we developed genus- and species-specific primers for PCR diagnostics of malaria, as well as a one-step effective method of DNA isolation from Giemsa-Romanovsky-stained thick blood smears. It was demonstrated that stained preparations could be a reliable source of plasmodial DNA, and the quality of preparations and storage time (10-20 years) did not interfere with the results of PCR analysis.

[Ca++ ion transport blockers as reversants of the drug resistance of malarial parasites. 2. The effect of praziquantel on the resistance to chloroquine and compound R-70-Zh of Plasmodium berghei]. / Blokatory transporta ionov Ca++ kak reversanty lekarstvennoi ustoichivosti maliariinykh parazitov. Soobshchenie 2. Vliianie prazikvantelia na ustoichivost' k khlorokhinu i soedineniiu R-70-Zh u Plasmodium berghei.

The reversing action of anthelminthic praziquantel (P) on the effect of chloroquine (C) and compound R-70-Zh (styrylquinazoline) was revealed on a Plasmodium berghei model (white inbred mice), using a LNK65 isolate with naturally reduced sensitivity to chloroquine and its polyresistant line LNK65CHLFR with acquired resistance to chloroquine/fansidar (selected in our laboratory). P (125 mg/kg) in combination with C showed a potentiating effect not only on the LNK65 isolate, but also on the LNK65CHLFR line, while investigated separately on this line, both drugs were not effective in tested doses. Moreover, the similar effect of C on the LNK65CHLFR line was achieved in the dose that was 4 times higher than that of P/C combination. P in a standard dose on the LNK65 isolate showed a more marked activation of compound R-70-Zh that on C. The potentiating effect was manifested in combination with R-70-Zh in the dose half as high as that of C; this phenomenon was also reflected by the efficiency index (5.0 against the 4.0) accepted in our laboratory and may be associated with the higher sensitivity of the LNK65 isolate to R-70-Zh. P showed some antimalarial action which manifested itself only by morphological changes on P. berghei parasites similar to those observed under the action of some dihydropholate reductase inhibitors, such as pyrimethamine.

[Ca++ ion transport blockers as reversants of the drug resistance of malarial parasites. 1. The effect of verapamil on the resistance to chloroquine in vivo of Plasmodium berghei and in vitro of Plasmodium falciparum]. / Blokatory transporta ionov Ca++, kak reversanty lekarstvennoi ustoichivosti maliariinykh parazitov. Soobshchenie 1. Vliianie verapamila na ustoichivost' k khlorokhinu in vivo u Plasmodium berghei i in vitro u Plasmodium falciparum.

The reversing action of verapamil on the effect of chloroquine was found in in vivo experiments by using a model P. berghei resistant to chloroquine, an LNK65 isolate having a naturally lower resistance to the agent, and its polyresistant strain with the acquired resistance to chloroquine and fansidar, as well as by employing the chlorine-resistant P. falciparum isolates from the south of the Socialist Republic of Vietnam. The magnitude of this effect was related to the dose of verapamil, the frequency of administration of a combination of the agents in vivo, while that was associated to the concentration of verapamil and the level of isolate resistance to chloroquine in vitro which was the most pronounced. Taking into account the dose-dependent effect of verapamil, it can be suggested that increasing its concentration in combination with chloroquine can provide a more marked reversing action with lower chloroquine concentrations. The parameters accepted by the authors in evaluating the combined effect enable the effect of the verapamil/chloroquine concentration to be regarded as potentiation.

[The search for new antiparasitic agents. 10. The synthesis, toxicological and antimalarial properties of nitrogen-containing heterocycles with a 4-(4-alkylpiperazinyl-1) phenylamine substituent (the preparation quinoprazine)]. / Izyskanie novykh protivoparazitarnykh sredstv. 10. Sintez, toksikologicheskkie i protivomaliariinye svoistva nekotorykh azotsoderzhashchikh geterotsiklov s 4-(4-alkilpiperazinil-1)fenilaminnym zamestitelem (preparat khinoprazin).

Synthesis is described and acute toxicity and antimalaria action is studied in new derivatives of quinoline and benzo(g)quinoline containing a 4-(4-alkylpiperazinyl-1)phenylamine substitute. Only the derivatives of benzo(g)quinoline were found to have a high antimalaria effect and to have advantages over the standard agent chloroquine on their tolerance and protective action. One of the compounds, 4-[4-(4-ethylpiperazinyl-1)phenylamino] benzo(g)quinoline, named QUINOPRAZINE, showed some action against Plasmodium berghei chloroquine--resistant infection (isolate LN-K65). This agent was elected for further tests.

[Drug resistance of malarial parasites and the methods for its determination]. / Lekarstvennaia ustoichivost' maliariinykh parazitov i metody ee opredeleniia.

The problem of drug resistance of Plasmodium falciparum, the causative agent of tropical malaria and its role in the general system of malaria control are discussed. The aspects of distribution of drug resistant strains of P. falciparum and the main principles of determination of the malaria causative agent sensitivity to antimalaria drugs are presented. The determination implies the use of various procedures for performing the tests under clinical conditions in vivo and various modifications of the in vitro tests, as well as estimation of their results. The use of a 48-hour in vitro test provided the revealing of certain advantages of dabequine, a new drug made in the USSR in comparison to chloroquine with respect to drug resistant strains of P. falciparum from the southern areas of Vietnam. The advantages and disadvantages or limitations of every procedure in comparison to the others are indicated and it is shown that the in vivo and in vitro tests are supplementing each other. The known procedures provide the results not earlier than in 24-48 hours which required developing of a rapid procedure. Brief characteristics of a rapid biochemical procedure are presented. This procedure was developed at the E. I. Martsinovsky Institute of Medical Parasitology and Tropical Medicine on an experimental model of P. berghei, the causative agent of rodent malaria. It provides the results in 4-5 hours.