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Biomedical subjects

W E Collins

Publications and source records attributed to W E Collins.

At least 235 records · Page 13Linked to original sources
PubMed1982

Failure to detect hypnozoites in hepatic tissue containing exoerythrocytic schizonts of Plasmodium knowlesi.

Sections of paraffin-embedded rhesus liver containing numerous nearly mature exoerythrocytic schizonts of the non-relapsing malaria parasite, Plasmodium knowlesi, were examined for the presence of hypnozoites by indirect immunofluorescence, employing both homologous and strongly cross-reacting heterologous sera. No hypnozoites or evident hypnozoite equivalents were detected in tissue which, by analogy with results obtained for the relapsing species, P. cynomolgi bastianellii, should have contained 35--50 of the uninucleate forms. These observations are presented as additional evidence in favor of the hypnozoite theory of malarial relapse.

Animals↗
PubMed1982

A survey of malaria in Indochinese refugees arriving in the United States, 1980.

During the months April-June and October-November 1980, a survey was conducted among Indochinese refugees arriving in California to assess the prevalence of malaria. During the two study periods, 3,433 refugees were met and 3,289 (95.8%) of the arriving refugees were screened for malaria by examining thick blood smears and by indirect fluorescent malaria antibody tests of blood absorbed on filter paper. Examination of the blood smears showed that the overall patency rates were 1.7% and 0.6% for the first and second surveys, respectively. The Cambodian Refugees and refugees from camps in Thailand had the highest patency rate in the first survey. In the second survey, the Cambodian refugees and refugees from camps in Indonesia had the highest patency rate. The average malaria seropositivity rate was 15% in the first and 13.6% in the second survey. The Laotian refugees had the highest rate of malaria seropositivity in both surveys. Plasmodium vivax was the most commonly identified species in blood examination, while a higher rate of seropositivity to P. falciparum was found in both surveys. This study indicates that the malaria infection rate was at least 1.7% based on blood smear examination but might be as high as 45% based on serologic examinations. The results of this study when combined with malaria surveillance indicate that the likelihood of introduced malaria in the United States from the Indochinese refugees is low.

Antibodies↗
PubMed1982

Role of insects in the transmission of bovine leukosis virus: potential for transmission by mosquitoes.

Bovine leukosis virus (BLV) was transmitted to sheep in a simulated mechanical transmission experiment, using the following species of mosquitoes; Anopheles freeborni, A stephensi, A quadrimaculatus, and A albimanus. Mosquitoes were fed on blood taken from a BLV-infected cow with persistent lymphocytosis. Mouthparts and heads of mosquitoes were removed immediately after feeding, placed in RPMI 1640 medium, and inoculated subcutaneously into sheep. Nine sheep were inoculated with mouthparts and heads from 37 to 122 mosquitoes. Infection was determined serologically. Three monthly serum samples were collected from the sheep and were tested for the presence of antibodies to BLV, using the agar-gel immunodiffusion (AGID) test. Sera that were negative by AGID at 3 months were tested by radioimmunoassay. Results from radioimmunoassay agreed with those obtained by AGID. Four of the 9 sheep developed antibody to BLV. Sheep that seroconverted were inoculated with mouthparts and heads from as few as 54 mosquitoes.

Animals↗
PubMed1982

Observations on two strains of plasmodium falciparum from Haiti in Aotus monkeys.

Two strains of Plasmodium falciparum originating in Haiti were studied in the Aotus monkey. The Haitian I/CDC strain was first adapted to in vitro cultivation and subsequently inoculated into monkeys. The Haitian III/CDC strain was inoculated directly from a human patient into the Aotus monkey. The strains varied in their levels of pathogenicity to the animals. The Haitian I/CDC strain was highly virulent in six splenectomized animals; in one intact animal, the infection could be controlled but not eliminated with periodic doses of quinine and chloroquine. After subsequent splenectomy, the animal developed high parasitemias and died. No gametocytes developed in any of the Haitian I infections. The Haitian III strain was lethal to five of the 14 splenectomized monkeys inoculated, but some were able to control their infections without drug intervention. Gametocytes developed in all infections that persisted for an adequate length of time, and infections of mosquitoes were obtained both during the primary attack and the first recrudescence of the parasitemia. Of the mosquitoes tested, Anopheles freeborni was most susceptible to infection, followed by An. culicifacies, An. dirus, An. maculatus, and An. albimanus. The Haitian III strain was successfully transmitted to four other splenectomized Aotus monkeys via sporozoite inoculation using An. freeborni.

Animals↗
PubMed1982

Studies on the Cambodian I strain of Plasmodium falciparum in Aotus monkeys.

The Cambodian I strain of Plasmodium falciparum, originally from Kampuchea was adapted for development in three different types of Aotus monkeys. High-level parasitemias were readily produced in splenectomized Colombian A. trivirgatus griseimembra monkeys. Initially, only minimal parasitemias developed in A. t. trivirgatus monkeys from Colombia. However, in one animal, adaptation occurred and high-level parasitemias were obtained during the second recrudescence of the infection. Passage to other A. t. trivirgatus monkeys indicated that the parasite was well adapted for development in splenectomized animals; low to moderate parasitemias were still produced in intact animals. This line of the parasite produced high level parasitemias when inoculated into splenectomized Aotus monkeys from Peru. Infections in Anopheles freeborni mosquitoes were obtained as late as the 7th passage in A. t. griseimembra monkeys and as late as the 7th recrudescence of the infection in an individual monkey (348 days after inoculation). The sporogonic cycle was completed in An. freeborni mosquitoes, and one transmission to an A. t. griseimembra monkey via the bites of infected mosquitoes was obtained.

Animals↗
PubMed1982

An analysis of civil aviation propeller-to-person accidents: 1965-79.

The interest of manufacturing, governmental, and safety personnel in using paint schemes on propeller and rotor blades is based on improving the visual conspicuity of those blades when they are rotating. While propeller and rotor paint schemes may serve to reduce the number of fatalities and injuries due to contact with a rotating blade, there is little information about the circumstances surrounding such accidents. Brief reports provided by the National Transportation Safety Board of all "propeller-to-person" accidents from 1965-79 were examined and analyzed in terms of airport lighting conditions, actions of pilots, actions of passengers and groundcrew, phase of flight operations, weather conditions, and others. Analyses based on 319 accidents showed a marked drop in the frequency of "propeller-to-person" accidents from 1975 through 1978. Several types of educational efforts directed toward pilots and groundcrew, both prior to and during that 4-year period, were examined as possible factors contributing to the accident rate decline. Accident patterns provide a basis for assessing the probable efficacy of various recommendations, including propeller conspicuity, for further reducing "propeller-to-person" accidents.

Accident Prevention↗
PubMed1982

A comparison of some effects of three antimotion sickness drugs on nystagmic responses to angular accelerations and to optokinetic stimuli.

While the basic efficacy of antimotion sickness drugs is rooted in the reduction of motion sickness symptoms, adverse side effects are important practical considerations of their usage in aviation. This study examined the influence of three established antimotion sickness drugs on nystagmic eye movement responses to angular acceleration (whole-body movement) with vision either permitted or denied, and to optokinetic stimulation (visual field movement). Dimenhydrinate and promethazine hydrochloride, particularly at higher dose levels, reduced optokinetic nystagmus, thereby making less accurate the following ability of the eye. During whole-body motion in darkness, there was little placebo-drug difference in the vestibular response under alert conditions; under relaxed conditions, dimenhydrinate and promethazine hydrochloride produced significant declines in the vestibular eye movements. These same drugs also interfered with the ability of the individual to fixate adequately on a visual task during motion. Subjects who received a combination of promethazine plus d-amphetamine were able to suppress vestibular eye movements and maintain good visual fixation under the task condition. Thus, the effect of a drug on nystagmus may be a poor indicator of its value in preventing motion sickness. Moreover, assessments of antimotion sickness drugs for many practical situations should include, as a possible adverse side effect, the inability to maintain visual fixation during motion.

Acceleration↗
PubMed1981

Malaria, sex, and place of residence as factors in antibody response to Epstein-Barr virus in Ghana, West Africa.

Both Epstein-Barr virus and malaria have been implicated as possible factors in Burkitt's lymphoma. To examine this implication a cross-sectional serological survey of an urban and a rural population in Ghana was conducted. Malaria was more prevalent in the rural areas, but there was no difference in antiviral capsid antigen (VCA) antibody titres between urban and rural dwellers. There was also no correlation between anti-malaria antibody titres and anti-VCA antibody titres. Thus malaria does not seem to influence immunological response to Epstein-Barr virus infection, as measured by anti-VCA antibodies. These results suggest that if Epstein-Barr virus infection and malaria are important in the aetiology of Burkitt's lymphoma, they produce their effects independently. The survey also showed that those in rural areas seroconverted earlier than those in urban areas, and that antibody levels were consistently higher in females than in males in every age-group. Case-control studies and screening programmes involving anti-VCA levels will therefore have to take these two findings into account.

Antibodies, Viral↗
PubMed1981

Cultivation in vitro of the vivax-type malaria parasite Plasmodium cynomolgi.

The vivax-type simian malaria parasite Plasmodium cynomologi was cultured in vitro by both the candle jar method and the continuous flow technique, with rhesus monkey erythrocytes and RPMI 1640 medium supplemented with Hepes buffer and human serum. After 6 weeks in culture, the growth of the parasite had permitted a 5 X 10(6) cumulative dilution of the original inoculum. Cultured parasites remained infective to rhesus monkeys and exhibited a reversible decrease in the ameboid behavior of their trophozoites.

Blood↗
PubMed1981

Susceptibility of Peruvian Aotus monkeys to infection with different species of Plasmodium.

Splenectomized Aotus trivirgatus monkeys of Peruvian origin were tested for their susceptibility to infection with different species of Plasmodium. Strains of P. vivax from Vietnam and El Salvador produced infections in eight animals with maximum parasite densities ranging from 2,000-180,000 per mm3. A strain of P. falciparum from Cambodia produced maximum parasitemias in five animals ranging from 8-25% of the red blood cells infected. Although two monkeys inoculated with P. fragile had maximum parasitemias of 31% and 42%, treatment was not necessary for animal survival. Three monkeys infected with P. knowlesi via the bites of infected mosquitoes had maximum parasitemias of from 25-41%; these animals died of their infections. Nine animals were infected with P. cynomolgi; maximum parasitemias in seven of these animals with no prior history of malarial infection ranged from 49,500 per mm3 to 11%; two animals with prior experience with P. vivax and P. fragile had maximum P. cynomolgi parasitemias of 65 and 13,200 per mm3. No infections were obtained in animals inoculated with P. coatneyi or P. hylobati.

Animals↗
PubMed1981

Experimental Babesia microti infections in Macaca mulatta: recurrent parasitemia before and after splenectomy.

To learn more about the course of Babesia microti infections in primates, six Macaca mulatta monkeys with blood-induced B. microti infections were followed for 270 days with regular thick blood smears. Three of the monkeys experienced from 1--3 recurrences of parasitemia defined here as greater than or equal to 200 organisms/mm3 blood. Following splenectomy on day 297, parasitemia recurred in all animals, reaching levels of 1.9 x 10(5) to 2.7 x 10(6) organisms/mm3, and was associated with a moderately severe hemolytic anemia. These findings suggest that similar recurrences of parasitemia may occur in human cases, and that splenectomy may present a risk to persons with a past history of B. microti infection.

Animals↗
PubMed1981

The 48-hour exoerythrocytic stage of Plasmodium cynomolgi bastianellii.

Detection and specific identification of the 48-hour exoerythrocytic stage of the primate malaria parasite, Plasmodium cynomolgi bastianellii, was accomplished by means of a highly specific indirect immunofluorescence technique (IFA) applied to hepatic tissue fixed in Carnoy's solution. The 48-hour forms appeared as round-to-slightly-oval bodies of average mean diameter 3.0 micrometers (9 parasites) and lying with the cytoplasm of individual hepatic parenchymal cells; each possessed one to three non-fluorescent nuclei or nuclear sections (mean 1.6) within the brightly fluorescent parasitic cytoplasm. In contrast, 72-hour parasites (6) had an average mean diameter of 4.0 micrometers and a mean of 2.2 nuclei. Restaining of IFA preparations with the Giemsa-colophonium method confirmed the plasmodial nature of fluorescent forms, despite some modification of staining characteristics produced by the prolonged exposure of sections to the aqueous phase of the IFA procedure. Exoerythrocytic forms could not be detected in biopsies obtained 24 hours following sporozoite inoculation.

Animals↗
PubMed1981

Antibody response to heterologous and homologous antigens in Brugia malayi- and B. pahangi-infected Mongolian jirds as measured by the enzyme-linked immunosorbent assay (ELISA).

Sequentially collected sera from Mongolian jirds (Meriones unguiculatus) infected with Brugia malayi and B. pahangi were tested for antibodies to homologous and heterologous antigens by the enzyme-linked immunosorbent assay (ELISA). Titers were less than 1:100 prior to infection and rose rapidly (within 2 weeks). Peak titers were observed prior to patent microfilaremia, and high titers persisted during infection. Use of the homologous antigen did not increase sensitivity or specificity of the ELISA. In fact, B. malayi-infected jirds demonstrated higher titers to the heterologous antigen, B. pahangi, than to the homologous antigen. Fractionation of B. malayi antigen over a wide pH range using isoelectric focusing did not eliminate cross-reactions, but the reactions of 20 B. malayi sera and 20 B. pahangi sera tested more strongly to specific fractions, particularly in the lower pH range.

Animals↗
PubMed1981

Tick transmission of Babesia microti to rhesus monkeys (Macaca mulatta).

To determine whether Ixodes dammini is capable of transmitting Babesia microti to primates, infected nymphal ticks were allowed to feed on five Macaca mulatta. The monkeys were then followed for at least 60 days with daily thick blood smears for evidence of infection. Patent B. microti parasitemia developed in four of the five animals. Prepatent periods were 13, 18, 20, and 28 days. Maximum parasitemia ranged from 83 to 7,068 organisms/mm3 blood. Splenectomy 15-17 months after exposure to ticks results in recurrences of parasitemia in three of the four infected monkeys.

Animals↗
PubMed1981

The enzyme-linked immunosorbent assay (ELISA) for malaria. III. Antibody response in documented Plasmodium falciparum infections.

Serum specimens from patients in El Salvador, Central America, with slide-proven Plasmodium falciparum infections were examined for antibodies to P. falciparum using the enzyme-linked immunosorbent assay (ELISA) and the indirect fluorescent antibody (IFA) methods. Both serologic tests were positive in 78.1% of the 827 samples, both negative in 5.4%, the ELISA positive alone in 6.3%, and the IFA alone in 10.2%. Agreement between the serologic tests was better in the specimens with high positive titers (high IFA = high ELISA). Seropositivity rates and geometric mean titers were higher in the older (greater than or equal to 15 years) age groups for both ELISA and IFA; in such persons, the IFA was positive in 92% and the ELISA in 88%. The lowest seropositivity rates found by the ELISA were observed in children; 27.6% of 98 children less than or equal to 4 years of age were negative. A longer duration of infection as evidenced by the presence of gametocytes on the blood slide resulted in higher positivity rates by both ELISA and IFA. This phenomenon, particularly apparent in young children, supports the belief that the more important variable in determining the proportion of false negatives is previous malaria experience and not age. The results indicate that, while neither serologic test is appropriate as a diagnostic aid, both the ELISA and the IFA would be useful in epidemiologic investigations.

Adolescent↗