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Biomedical subjects

M Warren

Publications and source records attributed to M Warren.

At least 91 records · Page 5Linked to original sources
PubMed1980

The Chesson strain of Plasmodium vivax in Aotus monkeys and anopheline mosquitoes.

The Chesson strain of Plasmodium vivax was studied in Aotus trivirgatus monkeys. Parasitemia in intact and splenectomized animals was similar to that reported for this strain in man. Comparative infectivity studies with mosquitoes fed on infected monkeys indicated that the most susceptible was Anopheles freeborni, followed by An. balabacensis, An. culicifacies, An. maculatus, An. atroparvus, An. stephensi, An. quadrimaculatus, and An. albimanus. Transmissions via sporozoites from An. maculatus was demonstrated on two occasions; prepatent periods were 30 and 32 days.

Animals↗
PubMed1980

Studies on the West Pakistan strain of Plasmodium vivax in Aotus monkeys and anopheline mosquitoes.

The West Pakistan strain of Plasmodium vivax was established in 17 Aotus trivirgatus griseimembra monkeys. Parasitemias were moderate. Prior experience of the animals with P. falciparum and a heterologous strain of P. vivax resulted in a marked reduction in parasitemias, but maintenance of mosquito infectivity similar to that of animals with no prior malaria. Comparative infectivity studies indicated that this strain in Aotus monkeys was most infective to Anopheles freeborni mosquitoes followed by An. balabacensis balabacensis, An. maculatus, and An. culicifacies. Anopheles albimanus were infected only rarely. The intensity of the salivary gland infections was highest in An. maculatus followed by An. culicifacies, An. freeborni, and An. b. balabacensis. Transmission via mosquito bite was obtained once with An. freeborni and once with An. maculatus; prepatent periods were 20 and 25 days.

Animals↗
PubMed1979

Modulation of the acoustic startle reflex in humans in the absence of anticipatory changes in the middle ear reflex.

If a weak tone precedes an intense tone, then the acoustic startle eyeblink reflex elicited by the stronger stimulus is inhibited. It has been suggested that the leading stimulus gives rise to a protective middle ear reflex that attenuates the effective intensity of the second. This hypothesis was tested and disproved. In seven subjects intense tone bursts sufficient to elicit both intratympanic and eyeblink responses were presented sometimes alone and sometimes preceded at various lead times (25 to 400 msec) by a weak tone. The weak tone inhibited the amplitude of the eye blink to the strong tone, maximally at intervals of 100 to 200 msec, but was never seen to produce any of the anticipatory impedance changes that would be characteristic of middle ear reflex activity during the interval between the two stimuli.

Adolescent↗
PubMed1979

Experimental Babesia microti infections in non-splenectomized Macaca mulatta.

Eight non-splenectomized Macaca mulatta were inoculated intravenously with strains of Babesia microti that originally were isolated from 2 human cases of babesiosis and then were maintained in hamsters in the laboratory. Patent infections developed in 7 animals with peak parasitemias of 496 to 3,906 organisms/mm3 blood. Prepatent periods ranged from 15 to 46 days. Parasitemia persisted for at least 90 days in all animals and in one, organisms were still present 559 days after inoculation.

Animals↗
PubMed1979

Effect of sequential infection with Plasmodium vivax and P. falciparum in the Aotus trivirgatus monkey.

Aotus trivirgatus monkeys with prior experience with Plasmodium vivax were inoculated with P. falciparum via the bites of infected mosquitoes. The animals with prior malaria had higher parasitemias and significantly higher levels of mosquito infectivity than monkeys with no prior P. vivax experience. Monkeys with a history of P. falciparum that were inoculated with P. vivax had essentially the same parasitemias as those with no prior malaria. However, levels of mosquito infectivity were markedly increased in those monkeys with a history of P. falciparum. The results imply that the introduction of another malaria species into a malarious area may result in higher levels of mosquito infection and more rapid establishment and distribution of that species.

Animals↗
PubMed1979

Studies on the West African I strain of Plasmodium falciparum in Aotus trivirgatus monkeys.

The West African I strain of Plasmodium falciparum was isolated from a commercial airline pilot who had an overnight stay in Nigeria. Once established in the Aotus trivirgatus griseimembra monkey, the parasite produced high parasitemias and readily infected mosquitoes. Anopheles freeborni and An. maculatus mosquitoes transmitted the infection to additional animals. Infected salivary glands were also seen in An. culcifacies. Comparative infectivity studies indicated the most susceptible mosquito to be An. freeborni, followed by An. culicifacies, An. maculatus, and An. balabacensis balabacensis. Only 2 An. albimanus mosquitoes were infected out of 450 examined. The one A. t. trivirgatus monkey inoculated with this strain had very low levels of parasitemia.

Animals↗
PubMed1979

Infectivity of Plasmodium simium to Aotus trivirgatus monkeys and different anophelines.

Infections of Plasmodium simium were induced in splenectomized and intact Aotus trivirgatus griseimembra monkeys by parasitized blood and by sporozoites from Anopheles freeborni mosquitoes. Eleven of 13 monkeys developed infection after sporozoite inoculation; prepatent periods ranged from 11 to 25 days (mean 15.8 days). Comparative infectivity studies indicated that An, freeborni mosquitoes were the most susceptible followed by An. stephensi, An. Balabacensis balabacensis, An. maculatus, An. quadrimaculatus, An. culicifacies, and An. albimanus. Studies with 3 pupal phenotypes of An. freeborni indicated that lines containing the green and nonstriped pupal phenotypes were more susceptible than the base colony; the striped phenotype was slightly less susceptible.

Animals↗
PubMed1978

Epidemic malathion poisoning in Pakistan malaria workers.

In 1976, epidemic organophosphate insecticide poisoning due to malathion occurred among 7500 field workers in the Pakistan malaria control programme. In July, the peak month of the epidemic, it is estimated that there were about 2800 cases. In field studies low red-cell cholinesterase activities were associated with the signs and symptoms of organophosphate insecticide intoxication. Toxicity was seen with 3 different formulations of the insecticide and was greatest with the products containing increased amounts of isomalathion, a toxic malathion degradation product. Poor work practices, which had developed when D.D.T. was the primary insecticide for malaria control, resulted in excessive skin contact with and percutaneous absorption of the pesticide. Airborne malathion concentrations were very low. Implementation of good work practices and proscription of use of the 2 pesticide formulations most contaminated with isomalathion halted the epidemic in September. An extensive training programme and surveillance system for pesticide toxicity preceded 1977 spraying operations.

Cholinesterases↗
PubMed1978

Field evaluation of primaquine in the control of Plasmodium vivax.

Two regimens of primaquine in combination with amodiaquine have been compared with amodiaquine alone in known cases of Plasmodium vivax in an endemic area of El Salvador, C.A. A 5-day regimen of primaquine, with dosages based on an adult dose of 15 mg per day, produced a substantial reduction in the numbers of patients experiencing renewed parasite activity and in the number of parasitemias experienced by the group during 9 mo of posttreatment observation, when compared with patients treated only with amodiaquine. A single dose regimen, based on an adult dose of 45 mg, similarly reduced the number of patients with renewed parasite activity and the number of parasitemias in the group. Those patients who experienced malaria attacks subsequent to treatment with either primaquine regimen experienced fewer such attacks than did those receiving amodiaquine alone. It is concluded that such primaquine regimens, which are more practicable for field use than the full 14-days curative regimen, are of value to both the patient and the community through the reduction of parasite episodes and the reduction of the source of mosquito infection for continuation of transmission.

Adolescent↗
PubMed1977

The seroepidemiology of malaria in Middle America. IV. Passage of malaria antibodies from mothers to infants.

In an area of El Salvador moderately endemic for malaria, use of the indirect fluorescent antibody test (IFA) showed that 44% of the infants born to mothers who had IFA responses to Plasmodium vivax of 1:20 or higher during the latter part of their pregnancy had positive IFA responses of 1:10 or higher to this antigen. No serum from an infant was positive in the absence of some level of malarial response in the mother.

Antibodies↗
PubMed1977

Morphologic variants of Anopheles albimanus and susceptibility to Plasmodium vivax and P. falciparum.

Three morphologically different, true-breeding phenotypes have been isolated from a strain of Anopheles albimanus from Lake Apastepeque, El Salvador. Studies with coindigenous strains of Plasmodium vivax and P. falciparum show that these phenotypes differ significantly in their susceptibility to malaria parasites. This difference is apparent both in the number of mosquitoes that become infected and the level of infection obtained. Variations in malaria susceptibility are markedly greater with P. vivax than with P. falciparum. The significance of genetic variants within a local vector population with respect to the epidemiology of malaria is discussed.

Animals↗
PubMed1977

Studies on the Santa Lucia (El Salvador) strain of Plasmodium falciparum in Aotus trivirgatus monkeys.

The Santa Lucia strain of Plasmodium falciparum was isolated from El Salvador, Central America, and established in Aotus trivirgatus monkeys. Transmission from monkey to monkey via the bites of infected Anopheles freeborni, A. maculatus, and A, albimanus mosquitoes was obtained in 20 of 27 attempts. Prepatent periods in the monkeys ranged from 17 to 46 days with a mean of 24.3 days. Parasitemias and mortality were higher following sporozoite inoculation into animals which had been previously infected with P. vivax than in those with no previous malaria experience. Monkeys previously infected with P. vivax and P. cynomolgi had lower maximum parasitemias than those previously infected with P. vivax only.

Animals↗
PubMed1977

Infectivity of the Santa Lucia (El Salvador) strain of Plasmodium falciparum to different anophelines.

Anopheles freeborni mosquitoes were much more heavily infected with the Santa Lucia strain of Plasmodium falciparum from coastal El Salvador than were any of the other species tested. Of 5 strains of A. albimanus examined, the most heavily infected was the CA-109A and the least was the Melara, both of which come from coastal El Salvador. Of the exotic anophelines, the A. maculatus was infected at a slightly higher level than was the A. balabacensis. The incidence of highly infected individual mosquitoes was greatest in the Panama-Escobal strain of A. albimanus from the Republic of Panama; the incidence was lowest in the Melara strain from El Salvador. All strains of A. albimanus developed infected salivary glands, but the A. freeborni and A. maculatus mosquitoes appeared to develop infected glands more effeciently. Infection rates in A. freeborni mosquitoes were highest if mosquitoes were fed on Aotus trivirgatus monkeys between the 19th and 25th days of patent gametocytemia.

Animals↗
PubMed1976

The seroepidemiology of malaria in Middle America. III. Serologic assessment of localized Plasmodium falciparum epidemics.

Epidemiologic studies were done in two localities, one in Panama and one in El Salvador, where outbreaks of Plasmodium falciparum malaria occurred. The indirect fluorescent antibody (IFA) method was helpful in defining the intensity of the outbreaks, the species of parasite involved, and, through parallel surveys of adjacent localities, the localized character of outbreaks. In Escobal, Panama 71 (34%) of 211 persons examined were IFA-positive for P. falciparum, although only 1 positive blood film was seen in this survey. In Jocomontique, El Salvador, 15 (28%) of 53 persons examined were IFA-positive for P. falciparum; 6 persons were parasite-positive. In the Panama study a number of children with positive IFA titers at the time of the epidemic had reverted to negative 6 months later. This lability of titers, in children, probably resulting from very early treatment of their first infection and, thus, a very brief exposure to the parasite antigen, suggests the need for caution in interpreting such negative serologic findings. Serologic studies provide valuable information in malaria epidemics, but must be interpreted in association with other known epidemiologic factors in the area concerned.

Adolescent↗
PubMed1976

Studies on human malaria in Aotus monkey. VII. Comparative infectivity of two strains of Plasmodium vivax to to Anopheles freeborni, A. maculatus, and for strains of A. albimanus.

A strain of Plasmodium vivax from El Salvador was shown to be more infectious to the Apastepeque strain of Anopheles albimanus from El Salvador than was a strain of P. vivax from Colombia, S. A. The Apastepeque mosquito strain was also more susceptible to the Savadoran strain of P. vivax than were 2 other strains of this mosquito from El Salvador. A strain of A. albimanus from Panama was more susceptible to both of the parasite than were any of the Salvadoran strains of A. albimanus.

Animals↗
PubMed1975

Effect of tolamolol and propranolol on exercise heart rate and angina.

Fifteen patients with angina pectoris participated in a double-blind study evaluating the effect of intravenous saline, 10 mg of intravenous tolamolol, 20 mg of intravenous tolamolol, and 10 mg of intravenous propranolol on resting and exercise heart rate and on exercise time until angina. Twenty mg of tolamolol and 10 mg of propranolol caused a similar decrease in mean resting heart rate, heart rate after a similar amount of exercise, heart rate at angina, resting product of systolic blood pressure times heart rate, and product of systolic blood pressure times heart rate at angina and were, therefore, judged equipotent. Tolamolol, 10 and 20 mg, and propranolol, 10 mg. were not followed by a significant change in mean exercise duration until angina, but there was a 25 percent increase in exercise time until angina in 4 of 15 patients (27 percent) after 10 mg of propranolol and in 3 of 15 patients (20 percent) after 20 mg of tolamolol.

Adult↗