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Biomedical subjects

W E Collins

Publications and source records attributed to W E Collins.

At least 253 records · Page 14Linked to original sources
PubMed1981

The selection of air traffic control specialists: history and review of contributions by the Civil Aeromedical Institute, 1960-80.

For two decades, the FAA Civil Aeromedical Institute ((CAMI) has explored the problems of effectively selecting air traffic control specialists (ATCSs) for the FAA. The results of those efforts have contributed directly to the establishment of revised ATCS selection standards by the Civil Service Commission (CSC). Early studies on the validity of aptitude tests for predicting successful completion of Academy training led to a decision to use such tests for part of the CSC screening standard. Later studies led to the establishment of a maximum age standard of 30 years for entry into ATCS training. In addition, CAMI researchers have continuously evaluated the validity of existing standards, have examined numerous variables and alternative aptitude measures, and have provided a number of data-based recommendations in an effort to improve predicting of success in ATCS training. This paper reviews that research with emphasis on aptitude screening measures, attrition, age, prior experience, education, sex, military ATCS training, and the Uniform Guidelines on Employee Selection.

Adult↗
PubMed1981

Development of Plasmodium inui in the Aotus trivirgatus monkey.

Four splenectomized Aotus trivirgatus griseimembra monkeys were affected with the OS strain of Plasmodium inui, a parasite of Old World macaques. High parasite densities were obtained and two of the animals died. Surviving animals maintained low to moderate level of chronic infections. Three of the four animals produced parasitemias which infected Anopheles dirus mosquitoes; oocyst densities were very low, however.

Animals↗
PubMed1980

Cultivation in vitro of the quartan malaria parasite Plasmodium inui.

The simian guartan malaria parasite Plasmodium inui (OS strain) was cultured in a continuous flow system with rhesus monkey erythrocytes and RPMI 1640nmedium supplemented with Hepes buffer and rhesus serum. Over a 10-week period, the growth of the parasite permitted a 61,000-fold cumulative dilution of the original inoculum. After 5 weeks in culture, the parasites were still infective to the monkey Saimiri sciureus and to Anopheles freeborni mosquitoes.

Animals↗
PubMed1980

Comparative studies of three strains of Plasmodium falciparum isolated by the culture method of Trager and Jensen.

The ease which Plasmodium falciparum parasites adapt to culture by the method of Trager-Jensen is variable. The strain characteristics of the first three isolates we cultured differed markedly, depending on the ease of adaptation. The West African I, which was cultured readily, proved to be sensitive to all antimalarials assessed by an in-vitro method, caused benign infections in Aotus monkeys, and produced gametocytes both in the cultures and in Aotus monkeys. In contrast, parasites of the Liberian I and Haitian I strains, both of which required an adaptive period of a month or longer proved more tolerant to chloroquine, quinine, and cycloguanil but sensitive to pyrimethamine; commonly produced fatal infections in Aotus monkeys, and did not produce demonstrable gametocytemia. That the differences may be due to the selection of a more virulent and drug tolerant subpopulation is suspected. The implication of these findings, particularly as it may apply to the epidemiology of chloroquine resistant falciparum malaria, is discussed.

Animals↗
PubMed1980

Serologic studies on onchocerciasis in Guatemala using fixed-tissue sections of adult Onchocerca volvulus.

Sera from 458 residents of a coffee plantation in an area of Guatemala endemic for onchocerciasis were examined for the presence of antibodies to Onchocerca volvulus using a fluorescent antibody (IFA) test with sections of adult worms as the antigen. Antibody response increased with age of the residents and microfilarial density. A total of 70.0% of the residents were serologically positive and 65.1% were positive for microfilariae. Males had higher microfilarial densities and higher IFA responses. Sixty-three individuals were positive for microfilariae and IFA-negative indicating a lack of sensitivity on the part of the test antigen. Seventy-four individuals were negative for microfilariae and IFA-positive, suggesting the possible usefulness of the test in the determination of present or past infection in the absence of microfilariae.

Adolescent↗
PubMed1980

Seroepidemiological studies of malaria in pregnant women and newborns from coastal El Salvador.

A cohort of 113 women and their newborns from the coastal area of El Salvador were studied longitudinally to estimate malaria incidence and indirect fluorescent antibody (IFA) response to malaria infection. The district in which the study was conducted had an estimated annual parasite index of 600/1,000 inhabitants, and all malaria infections were treated immediately with a 4-aminoquinoline. In the third trimester of pregnancy, the IFA response to Plasmodium falciparum was significantly depressed. As a result of antimalarial therapy and depressed immune responsiveness, 49% (P. vivax) and 53% (P. falciparum) of the pregnant subjects had a malaria IFA titer less than 1:20 at the time of delivery. Malaria IFA crossed the placenta to the fetus with a step-down of approximately a 4-fold dilution, except for the step-up noted in the P. falciparum titer for 17 of 116 newborns. Due to the overall low prevalence and intensity of maternal IFA, a titer of at least 1:20 was passed to only 23% (P. vivax) and 45% (P. falciparum) of newborns. Passively-acquired malaria IFA degraded with a half-life estimated between 43 and 52 days. During follow-up of infants to 6 months of age, no protection from malaria resulting from passively-acquired antibody could be demonstrated. Because of the limited transplacental immunization of these newborns with antimalarial antibody, it appears that passive immunity can exert little effect on the incidence of infant malaria in coastal El Salvador.

Antibodies↗
PubMed1980

Evaluation of the micro enzyme-linked immunosorbent assay for antibodies to Trypanosoma cruzi.

A micro enzyme-linked immunosorbent assay (ELISA) for antibodies to Trypanosoma cruzi was evaluated and the results obtained by ELISA were compared with those obtained by the complement fixation test (CF) and indirect fluorescent antibody test (IFA). Fifty sera collected from residents of the southeastern United States all had reciprocal ELISA titers less than or equal to 320. Similarly, serum samples from 17 patients with T. cruzi infection proven by xenodiagnosis had reciprocal ELISA titers of greater than or equal to 1,280. Specimens from 302 El Salvador Army recruits were tested by ELISA, IFA, and CF. Excellent correlation was observed between results obtained by the three serologic tests; 62.9% of the samples were negative by each of the three tests and 24.5% were positive by all. Overall, 29.5% of the sera were positive for antibodies to T. cruzi by ELISA, 29.5% by IFA, and 31.5% by CF. The data suggest that the micro ELISA is a promising serologic test for measuring antibodies to T. cruzi in individuals and in populations.

Adolescent↗
PubMed1980

Transmission of Plasmodium vivax from Vietnam by four different anophelines.

Infections of the SV-I strain of Plasmodium vivax from Vietnam were transmitted via the bites of infected Anopheles stephensi, An. maculatus, and An. balabacensis balabacensis mosquitoes. Infected salivary glands were also found in An. freeborni mosquitoes. In 18 successful transmissions, prepatent periods ranged from 10--17 days. Four black volunteers failed to develop infections even though they were fed upon by heavily infected An. maculatus and An. b. balabacensis mosquitoes.

Anopheles↗
PubMed1980

Anopheles pseudopunctipennis: laboratory maintenance and malaria susceptibility of a strain from El Salvador.

The techniques involved in the establishment of a strain of Anopheles pseudopunctipennis pseudopunctipennis from El Salvador, Central America are presented. Results of experimental susceptibility studies using coindigenous strains of Plasmodium falciparum and P. vivax as well as P. vivax from Colombia indicated that this anopheline strain does not possess the biologic capability for malaria transmission. The usefulness of biological susceptibility data in establishing the vector status of anophelines, especially in areas with multiple species as potential vectors, is discussed.

Animals↗
PubMed1980

The serological response to primary malaria infection in urban Ghanaian infants.

Thirty-one (31) newborn infants living in Accra, Ghana, were visited monthly for the first 15 months of life to determine their serologic response to primary malaria infection. Only 10 episodes of seroconversion were observed, the earliest occurring at the 5th month and at a time when maternal-acquired antibodies were absent. Following seroconversion, antibody titers peaked at the 1st month but were generally of low titer (mean geometric titers < 1:80) and declined to undetectable levels within a few months. The majority of the seroconverting infants had no symptoms of illness although in three of the 10 episodes splenic enlargement was noted. This study suggests that symptoms of malaria infection in infancy are often minimal, but that the moderation of symptoms is due to factors other than maternally transmitted antimalarial antibodies. Additionally, malaria appears to be much less common than expected in this urban area of West Africa.

Age Factors↗
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↗
PubMed1980

Infection and transmission studies with Plasmodium gonderi in the Macaca mulatta monkey.

Eight different anophelines--Anopheles freeborni, An. maculatus, An. dirus, An. stephensi, An. atroparvus, An. sundaicus, An. quadrimaculatus, and An. albimanus--were shown to be susceptible to infection with a strain of Plasmodium gonderi from the drill. Mandrillus leucophaeus. Transmission was obtained via the bites of An. freeborni, An. maculatus, An. stephensi, and An. dirus mosquitoes to Macaca mulatta. Prepatent periods in Macaca mulatta monkeys following sporozoite inoculation ranged from 7 to 15 days with a median of 12.5 days. Relapses from fixed-tissue stages following treatment with chloroquine or quinine sulfate were not demonstrated.

Animals↗
PubMed1979

Chloroquine-resistant Plasmodium falciparum from East Africa: cultivation and drug sensitivity of the Tanzanian I/CDC strain from an American tourist.

A strain of Plasmodium falciparum, designated Tanzanian I/CDC, from an American tourist returning from Tanzania, was isolated in vitro and in the Aotus monkey. Clinically, the infection showed a late recrudescent pattern of chloroquine resistance. In 2 inoculated Aotus monkeys, the infection recrudesced after a dose of chloroquine (40 mg/kg) curative for sensitive P. falciparum strains in the Aotus monkey. In 4 ,dditional monkeys two primary infections and one of the recrudescent parasitaemias were cured with a 100 mg/kg dose of chloroquine; the second recrudescent parasitaemia was cured with an additional 40 mg/kg dose of chloroquine. The 48 h in-vitro chloroquine-sensitivity test demonstrated that the Tanzanian I/CDC strain had a pattern of chloroquine resistance similar to a reference resistant strain, the Vietnam-Oak Knoll (FVO). These studies reinforce reports which suggest that chloroquine-resistant malaria is being transmitted in East Africa.

Blood↗