Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Riboflavin deficiency inhibits the growth of malaria parasites both in vitro and in vivo in infected animals and humans. Although the precise mechanisms underlying this inhibition are unknown, they may involve enhanced requirements for riboflavin by parasites. To investigate this possibility, the rate of uptake of [14C]riboflavin and the biosynthesis of FMN and FAD from riboflavin were studied in infected (5-8% parasitemia) and uninfected human erythrocytes. All cells were incubated for 0-3 h at 37 degrees C in phosphate buffered saline containing MgCl2, glucose, and [14C]riboflavin (2.5-7.5 microM). At hourly intervals, samples were removed, centrifuged, washed twice with cold buffer, and lysed before counting the radioactivity. The rate of in vitro biosynthesis of FMN and FAD from riboflavin in erythrocytes was measured by ion exchange chromatography and reverse isotope dilution techniques. Results showed that the rate of riboflavin uptake and the biosynthesis of FMN and FAD were enhanced in erythrocytes with parasitemia as compared with results in unparasitized erythrocytes. Riboflavin uptake in erythrocytes was proportional to the extent of parasitemia and especially to percent of schizonts present in erythrocytes. These studies indicate that the requirement for riboflavin may be greater in the parasite than in the host erythrocyte. This increased riboflavin requirement may be due to rapid multiplication, higher metabolic rate, and extreme vulnerability to oxidative stress of malaria parasites compared with that of host erythrocytes. The differential requirement of riboflavin by the host and the malaria parasite may hold important potential for developing new strategies for malaria chemotherapy.
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PMID:Enhanced uptake and metabolism of riboflavin in erythrocytes infected with Plasmodium falciparum. 192 Jan 46

P. falciparum schizonts were found in peripheral blood of six malaria patients including two infants who were moderately ill, with parasitaemia ranging from 33920 to 410800 per cubic mm. The patients lived in villages located at an altitude of 680 m and the phenomenon was observed during the cold season when transmission was high. Appearance of these forms was independent of host age.
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PMID:Detection of early dividing forms of Plasmodium falciparum in peripheral blood. 218 8

The properties of a purine phosphoribosyltransferase from late trophozoites of the human malaria parasite, Plasmodium falciparum, are described. Enzyme activity with hypoxanthine, guanine and xanthine as substrates eluted in parallel during hydroxylapatite, size exclusion and DEAE-Sephadex chromatography as well as during chromatofocusing experiments. Furthermore, enzyme activity with all three purine substrates changed in parallel during heat inactivation of enzyme preparations and upon cold storage (4 degrees C) of the enzyme. When considered together, these results support the view that the phosphoribosyltransferase is capable of utilizing all three purine bases as substrates. Additional characterization revealed that the apparent molecular weight and isoelectric point of this enzyme are 55,500 and 6.2, respectively, and that the apparent Km for 5-phosphoribosyl-1-pyrophosphate ranges from 13.3 to 21.4 microM, depending on the purine base serving as substrate. The apparent Km values for hypoxanthine, guanine and xanthine were found to be 0.46, 0.30 and 29 microM, respectively. Other experiments showed that several divalent cations and sulfhydryl reagents produce a marked reduction of enzyme activity whereas dithiothreitol activates the enzyme. It should be noted that the ability to utilize xanthine as a substrate serves to distinguish the P. falciparum enzyme from its counterpart in the parasite's host cell, the human erythrocyte. The human enzyme shows only barely detectable activity with xanthine while the parasite enzyme displays similarly high levels of activity with all three purine substrates. Thus, the parasite enzyme might prove to be selectively susceptible to inhibition by xanthine analogs and related compounds.
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PMID:Properties and substrate specificity of a purine phosphoribosyltransferase from the human malaria parasite, Plasmodium falciparum. 305 May 15

Although the prevention of infection through immunization is a central goal of maternal-child health programs in all developing countries, it is important to recognize that the role of vaccines varies greatly from country to country, from infection to infection, and from vaccine to vaccine. Immunization strategies must be as responsive to local disease patterns, needs, and opportunities as to technological advances in the creation, production, storage, and delivery of vaccines. This paper outlines the present state of the art for vaccines against measles, pertussis, poliomyelitis, tetanus, and tuberculosis. Other childhood infections in the tropics in need of a vaccine are the enteric infections, serious bacterial infections, vertically transmitted viral infections, and parasitic infections such as malaria. Immunization technologies related to the cold chain, delivery techniques, and adjuvants are constantly improving. Gains have also been made in outcome evaluation and disease surveillance. Ultimately, the success of the immunization effort depends on community participation and awareness.
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PMID:Recent advances in immunization. 331 42

A study was undertaken to determine disease prevalence of, choice of treatment for, as well as health services utilization by, preschool children living in a rural district of coastal Tanzania. Disease prevalence and choice of treatment were determined through seven-day recall; health services utilization through systematic analysis of Village Health Workers' service records over one calendar year. It was found that the main disease symptoms, i.e. fever, cough, diarrhea, difficult breathing, ear ache and sore throat occurred at frequencies of 15.6, 8.3, 5.7, 2.0, 1.7 and 0.4 episodes respectively, per child per year. Cough, difficult breathing, common cold and ear ache caused about 50% of all episodes of illness. The majority (61%) of all illness episodes were treated in dispensaries, health centres or hospitals. 18.9% were attended by Village Health Workers (VHWs), 14.5% received treatment at home and 3.5% were seen by traditional healers. The use of VHWs was associated with a reduction of home-treatment and reliance on traditional healers for the care of perceived illness. VHW's monthly reports revealed malaria to be the number one health problem both among children and adults, responsible for about 25% of all attendances.
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PMID:The burden of disease among preschool children from rural Tanzania. 338 32

In 1984 a rare opportunity arose to document the effects of contact on a previously isolated population in Papua New Guinea. The Hagahai, a small group of hunter-horticulturalists, remained hidden from government and mission influence until the early 1980s. Prior to that time, indirect contact through trade with neighboring peoples facilitated the entry of introduced infectious diseases. In late 1983 the Hagahai sought medical aid at a mission station, an event which accelerated their contact with the common epidemic diseases of the highlands. A wide variety of genetic, linguistic, ethnographic and medical data have been collected which document the historical sequence of events contributing to the current rapid demographic decline among the Hagahai. Serological evidence demonstrates the endemicity of Bancroftian filariasis, malaria, C. diphtheriae, cytomegalovirus, HTLV-1, the Ross River arbovirus and several viruses associated with the common cold. Recent epidemics include mumps, influenza A, and hepatitis B. They have not yet been affected by TB or measles, among others. Infanticide contributes to an estimated infant mortality rate of 568/1000. With a crude birth rate of 38 and a crude mortality rate of 51, the Hagahai appear to be dying out. The provision of adequate health care to these people is extremely problematic and beyond the capacity of the existing system.
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PMID:Health in the early contact period: a contemporary example from Papua New Guinea. 339 25

Characterization of cold reactive lymphocytotoxic antibodies present in sera from Thai adults with malaria revealed that the antibodies are predominantly 19S (IgM), directed against both autologous and allogeneic mononuclear cells, complement-dependent, present in titres ranging from 1:2 to 1:16, and exhibit greater lymphocytotoxic activity during the acute stage of malarial infection than during the convalescent stage. The lymphocytotoxic antibodies were primarily directed against B cell targets or both B as well as T cell targets. In addition some sera were reactive with enriched monocyte/macrophage indicator cells at 15 degrees C, but not 37 degrees C. Antibodies directed against B cell targets were lymphocytotoxic both at 15 degrees C as well as 37 degrees C. The results indicate that IgM lymphocytotoxic antibodies in the sera of patients with malaria are directed primarily against B cells with reactivity to a lesser extent against T cells and macrophages and thus may play an immunoregulatory function in the humoral immune response to malaria infection.
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PMID:Characterization of cold reactive lymphocytotoxic antibodies in malaria. 634 Aug 70

Because of the potential for the elimination of lymphocytes through anti-lymphocytotoxic antibodies we examined individual sera of patients infected with falciparum or vivax malaria for the presence of antibodies against normal peripheral blood mononuclear cells. In assays done at 15 degrees C, 95% of the P. falciparum patients and 98% of the P. vivax patients showed evidence for antibody activity. Activity at 37 degrees C was significantly less than that at 15 degrees C. These studies suggest that infection with malaria induces anti-lymphocytotoxic antibodies which are predominantly cold-reactive. It is possible that this phenomenon plays a role in modulating the immune response of patients toward malaria.
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PMID:Anti-lymphocytotoxic antibodies in sera of Thai adults infected with Plasmodium falciparum or Plasmodium vivax. 699 Nov 73

The incidence of multiple births among the Hausa population in Katsina, Nigeria, is studied. Hospital maternity records for 5750 women delivering in 1974-1978 revealed 228 sets of twins and 12 sets of triplets, for a twinning rate of 39.7/1000 births, a triplet rate of 2.1/1000 births and a multiple birth rate of 41.7/1000; about 4 times the rate in Western countries. Data from the hospital's catchment area indicate that the results are valid for the area, but lower than for other parts of Nigeria. The incidence increased gradually with advancing maternal age, peaking at 30-34 years. The twinning rate gradually increased with birth order, with peak incidence at parity 5. The greatest incidence of triplets occurred at parity 7 or above, lower parities showed no consistent trend. Age and parity had independent effects of the twinning rate; the results are similar to those obtained in other studies. The most common presentation for twins was vertex/vertex (60%); for triplets, vertex/vertex/breech. Of the 190 cases where the twins' sex was recorded, 63.2% were like-sexed. The sex ratio was 1.29. Of 9 sets of triplets, 3 sets were all male, 3 all female, and 3 mixed. The sex ratio was 1.08. 26.3% of the twins were monozygous. Advancing maternal age had a more profound effect on the incidence of dizygous twins than on monozygous twins. The mean birth weight of the twins was 2.2 kg and for triplets 1.7 kg; lower than for full term singleton Hausa infants. Among the twins, 51 were stillborn and mortality was higher among like-sexed infants. Among the triplets, 6 were stillborn. Pregnancy duration averaged 268.5 days and was lower than singleton deliveries. Complications associated with twins included: prematurity (11.5% of the cases), postpartum hemorrhage (1.6%), and hydramnios (.9%). The effects of climate on the multiple birth rate is unclear. Some studies have shown a higher incidence in hot, humid climates. In this study, a higher incidence was observed among conceptions occurring in the cold, dry season. Some researchers have suggested a causal relationship between malaria and the incidence of twinning which was not confirmed in this study.
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PMID:Multiple births in Hausa women. 743 72

Biology of malaria vectors were studied in Kheda district of central Gujarat in order to understand the vector behaviour in the wake of ecological changes. Anopheles culicifacies and An. stephensi were mainly endophilic whereas An. fluviatilis exhibited marked exophily. All the three vectors were predominantly zoophilic. Peak biting activity period of An. culicifacies varied with season though biting continued in varying magnitudes throughout the night. An. stephensi and An. fluviatilis were arhythmic in their biting activity. Survival of all the three vectors was maximum during cold season owing to longer gonotrophic cycle which also yielded higher estimates for expected infective life. Instability of malaria in this area was probably due to low estimates of expected infective life for the three vectors. A wide range of breeding habitat preferences by An. culicifacies was observed whereas An. fluviatilis and An. stephensi showed restricted distribution.
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PMID:Biology of malaria vectors in central Gujarat. 771 61


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