Biomedical subjects

W E Collins

Publications and source records attributed to W E Collins.

At least 145 records · Page 8Linked to original sources

PubMed1988

Plasmodium malariae: distribution of circumsporozoite protein in midgut oocysts and salivary gland sporozoites.

The distribution of the circumsporozoite protein within developing Plasmodium malariae oocysts and salivary gland sporozoites was examined by immunoelectron microscopy using protein A-gold and a monoclonal antibody specific for the CS protein of P. malariae. Gold particles were found along the capsule of immature oocysts but rarely within the cytoplasm. Gold label was detected on the inner surface of peripheral vacuoles during oocyst maturation and the plasma membrane of the sporoblast. Salivary gland sporozoites and budding sporozoites in mature oocysts were labeled uniformly on the outer surface of their plasma membranes. The surface of sporozoites that ruptured into midgut epithelial cells were entirely covered with gold particles. No label was seen on the surface of sporozoites which ruptured into the midgut lumen. In addition, a rabbit polyclonal antibody against repeat a region of P. brasilianum CS protein reacted with P. malariae sporozoites.

Animals↗

PubMed1988

Plasmodium vivax: in vitro growth and reinvasion in red blood cells of Aotus nancymai.

Plasmodium vivax was maintained in experimentally infected Aotus nancymai. Positive monkeys were used as donors for culture material. After leucocyte removal with two different methods, including the classic CF11 method and a commercially available filter, parasites were grown under continuous shaking conditions in standard RPMI 1640, containing 20% human AB + serum. When mature schizonts were present, artificially induced reticulocytes from monkeys pretreated with the hemolytic drug phenylhydrazine HCl were added. Addition of reticulocytes and shaking were both necessary to realize a significant reinvasion under in vitro conditions. A strong positive correlation between the percentage of reticulocytes and in vitro invasion was demonstrated, and a preferential invasion into reticulocytes was demonstrated in vivo and in vitro using blood films stained with brilliant cresyl blue and counterstained with Giemsa.

Animals↗

PubMed1988

Plasmodium fragile: detection of a ring-infected erythrocyte surface antigen (RESA).

A ring-infected erythrocyte surface antigen (RESA) has been detected by modified immunofluorescence assay in erythrocytes infected with the simian malaria parasite, Plasmodium fragile. This RESA, of Mr 95,000, shares many characteristics with the RESA initially found in the human malaria parasite P. falciparum. Both antigens are found in the membrane of erythrocytes infected with young asexual parasite stages, in merozoite-enriched preparations, and in parasite culture supernatant. Since the RESA of P. falciparum has been shown to confer protective immunity and since P. fragile infection of rhesus monkeys mimics P. falciparum infection in humans, the finding of a RESA in P. fragile underlines the importance of this species as an animal model for antimalarial vaccines.

Animals↗

PubMed1988

Chloroquine treatment of falciparum malaria in an area of Kenya of intermediate chloroquine resistance.

106 children aged 1-10 years who had pure Plasmodium falciparum infections and temperatures greater than or equal to 38 degrees C were treated with chloroquine base, 25 mg/kg body weight. 29% of the infections were sensitive in vivo, 41% recurred within 4 weeks (RI), 26% were RII resistant, and 4% were RII resistant. Rieckmann micro in vitro tests were successful in 64% of isolates obtained from these children; 63% were resistant to chloroquine. In 58 paired isolates obtained before and after treatment, the level of chloroquine sensitivity was lower in the parasites persisting or recurring after treatment. All children except 2 of the 4 with RIII resistance became afebrile an average of 1.4 d after starting treatment and their other symptoms resolved in an average of 1.8 d. By day 28, 57% of the children with RI resistance and 78% of those with RII resistance had recurrence of fever and other symptoms, compared with 19% of children with sensitive infections. No relationship was observed between the clinical or parasitological response and age, nutritional status, haematocrit, splenomegaly, presence of sickle-cell trait, or seropositivity to malaria by enzyme-linked immunosorbent assay. The study demonstrates that, in most children with malaria in an area of intermediate chloroquine resistance, fever and other symptoms resolve at least temporarily when treated with chloroquine.

Animals↗

PubMed1988

Structure of the circumsporozoite gene of Plasmodium malariae.

The sequence of the gene encoding the circumsporozoite protein of Plasmodium malariae was determined. The central immunodominant region of the protein consists of 45 copies of the sequence Asn-Ala-Ala-Gly and 6 copies of the sequence Asn-Asp-Ala-Gly. The CSP of the monkey parasite Plasmodium brasilianum contains the same repetitive sequences. Further comparison of the two genes in regions outside the immunodominant domains reveals only three nucleotide differences and each results in an amino acid change. One is centered in a putative T-cell determinant bearing region, the second is in the putative liver binding site, and the third is part of a degenerate repeat at the start of the immunodominant region.

Amino Acid Sequence↗

PubMed1988

Circumsporozoite protein of the human malaria parasite Plasmodium ovale identified with monoclonal antibodies.

Monoclonal antibodies (MAbs) have been produced against Plasmodium ovale sporozoites and used to characterize the circumsporozoite (CS) protein. Six MAbs were produced, and all were species specific. By using Western blot (immunoblot) analysis, three polypeptides were detected: a predominant 51,000-Mr polypeptide and two presumed precursor 57,000- and 67,000-Mr molecules. The presence of a repeating epitope in the CS protein of P. ovale was demonstrated by using one of the MAbs in a single-antibody two-site enzyme immunoassay. Three MAbs recognized epitopes on the surfaces of sporozoites; the presence of at least one other epitope within the CS protein, but not on the surfaces of P. ovale sporozoites, was also demonstrated.

Animals↗

PubMed1988

Antibodies to the ring-infected erythrocyte surface antigen of Plasmodium falciparum elicited by infection with Plasmodium malariae.

The ring-infected erythrocyte surface antigen (RESA) of Plasmodium falciparum (RESA-P), found in the membrane of erythrocytes infected with young asexual stages of P. falciparum, is a promising vaccine candidate. Antibodies to RESA-P were inducible by infection with another human malaria species, P. malariae. Of 298 serum samples from inhabitants of three isolated localities in Peru where P. vivax and P. malariae were endemic and P. falciparum had never been reported, 26% had anti-RESA-P antibodies as evidenced by a modified immunofluorescent-antibody assay and confirmed by Western blot (immunoblot) analysis. These seroepidemiologic observations were corroborated by the fact that of six chimpanzees infected with P. malariae, three developed anti-RESA-P antibodies after infection. The modified immunofluorescent-antibody-reactive antibodies, purified by adsorption and elution on monolayers of glutaraldehyde-fixed and air-dried P. falciparum-infected erythrocytes, reacted in an immunofluorescent-antibody assay with both parasite structures and erythrocyte membrane in P. falciparum antigen preparations, but only with parasite structures in P. malariae antigen preparations. This serologic cross-reactivity between P. falciparum and P. malariae is of interest in view of the importance of RESA-P as a vaccine candidate and because the two species are coendemic in many areas.

Animals↗

PubMed1988

Immunization trials with the ring-infected erythrocyte surface antigen of Plasmodium falciparum in owl monkeys (Aotus vociferans).

A protocol was developed for the testing of blood stage vaccines against Plasmodium falciparum using Peruvian Aotus vociferans and the Indochina I/CDC strain of the parasite. Three different fused polypeptide vaccines containing elements of the ring-infected erythrocyte surface antigen molecule combined with Freund's complete and Freund's incomplete adjuvants were tested to determine their ability to protect against overwhelming infection following challenge with this highly virulent strain of P. falciparum, and to invoke antibody responses as measured by a standard indirect immunofluorescence technique. Nine of 14 immunized animals exhibited some protection. Presented are the test procedures developed for the conduct of such trials with New World monkeys and the analysis of results that led to the identification of variables selected for study in future trials.

Animals↗

PubMed1988

Monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) for detection of Plasmodium malariae sporozoites in mosquitoes.

A monoclonal antibody specific for a repeated epitope of the circumsporozoite protein of Plasmodium malariae sporozoites has been used to develop a two-site, single antibody-based enzyme-linked immunosorbent assay that can detect P. malariae sporozoites in mosquitoes. The assay uses a purified monoclonal antibody produced against sporozoites of the Uganda I/CDC strain of P. malariae to capture the antigen and the same monoclonal antibody labeled with horseradish peroxidase as the detector. Sporozoites have been detected in laboratory-infected mosquitoes stored at room temperature in the presence of a desiccant for as long as 18 months. The detection limit of the assay is approximately 50 P. malariae sporozoites per test well. Cross-reaction has not been observed with mosquitoes infected with P. falciparum, P. vivax, or P. ovale sporozoites.

Animals↗

PubMed1988

In vitro cultivation of exoerythrocytic stages of the human malaria parasite Plasmodium malariae.

Exoerythrocytic stage parasites of Plasmodium malariae were obtained in vitro by inoculating primary cultures of hepatocytes from a chimpanzee (Pan troglodytes) and a monkey (Aotus lemurinus griseimembra) with sporozoites. Schizonts were observed in chimpanzee hepatocytes 8, 11, and 13 days after inoculation. Only 1 schizont was seen in Aotus hepatocytes at day 13. The morphology and development rates of P. malariae exoerythrocytic stages obtained in vitro were similar to those previously described in vivo.

Animals↗

PubMed1988

Antibody responses to malarial antigens in the Wopkaimin population of the Star Mountains, Papua New Guinea.

Antibody responses to malarial antigens were determined in 614 serum samples collected from the Wopkaimin population of the Star Mountains of Papua New Guinea. In point prevalence surveys made in 1982-1983, 33.7% of the persons examined were infected with Plasmodium falciparum, P. vivax, or P. malariae. Of these, 72.9% were infected with P. falciparum. In a standard fluorescent antibody test, highest level responses were to P. falciparum, followed by P. malariae, P. vivax, and P. ovale. A strong correlation was found between results of the fluorescent antibody tests and those obtained in an enzyme-linked immunosorbent assay using P. falciparum antigens. The failure of immune responses to eliminate these species of Plasmodium in this highly isolated population is discussed.

Adolescent↗

PubMed1988

Cultivation of exoerythrocytic stages of Plasmodium cynomolgi, P. knowlesi, P. coatneyi, and P. inui in Macaca mulatta hepatocytes.

Exoerythrocytic stage parasites of Plasmodium cynomolgi, P. knowlesi, P. coatneyi, and P. inui were cultured by inoculating primary cultures of hepatocytes from Macaca mulatta with sporozoites. Less than 1% of inoculated sporozoites survived. Morphology and size of the liver stages in all 4 species were similar to in vivo descriptions and the time required for in vitro maturation correlated well with prepatent periods described.

Animals↗

PubMed1988

Age, alcohol, and simulated altitude: effects on performance and breathalyzer scores.

Trained men in two age groups, 30-39 (n = 12) and 60-69 (n = 13), each performed at the Multiple Task Performance Battery in four separate full-day sessions with and without alcohol (2.2 ml of 100-proof vodka per kilogram of body weight) at ground level and at a simulated altitude of 12,500 ft (3,810 m). Subjects breathed appropriate gas mixtures through oxygen masks at both ground level and altitude. Mean breathalyzer readings peaked near 88 mg% and did not differ between age groups or altitude conditions. Younger subjects performed better than older subjects; performance of both age groups was significantly impaired by alcohol but these adverse effects were greater for the older subjects. No significant effects on performance were obtained due to altitude or to the interaction of altitude with alcohol. These results and those from several other studies suggest that prevalent views regarding the nature of the combined effects of alcohol and altitude on blood alcohol levels and on performance need to be redefined.

Adult↗

PubMed1988

Some effects of sleep loss on vestibular responses.

This study assessed ocular nystagmus and motion experiences of men exposed to both simple (angular acceleration) and complex (Coriolis) vestibular stimulation during approximately 55 h of sleep loss. Control and sleep-deprived groups each comprised 10 young men. Angular accelerations and Coriolis stimulation (30 degrees head movements during CW rotation) were accomplished in darkness in an enclosed Still-Werner rotating device. Nystagmus and motion experiences (turning, "diving," and "climbing") were recorded throughout each session. Tests were given at 0900 and 1300 on each of 3 successive days. Subjects ingested 10-mg of d-amphetamine at 1200 on Day 3. During simple stimulation, the sleep-deprived group showed regular declines across sessions in slow phase and duration measures of nystagmus but fast phase ocular frequency and measures of experienced turning resisted declines until the final predrug session; subjective response latencies increased with sleep loss. Declines during rotation for ocular output and measures of perceived displacement during rightward head tilts ("climbing" sensation) were obtained for the sleep deprived, but both nystagmus and sensations were unaffected by return (leftward) movements of the head ("diving" sensation). d-Amphetamine had no consistent effect on responses of control subjects, but significantly increased nystagmus and elevated (but not significantly) measures of turning experiences for the sleep deprived.

Adult↗

PubMed1988

Infection of Peruvian Aotus nancymai monkeys with different strains of Plasmodium falciparum, P. vivax, and P. malariae.

Aotus nancymai (karyotype I) monkeys from Peru were studied for their susceptibility to infection with Plasmodium falciparum, P. vivax, and P. malariae. Three strains of P. falciparum (Santa Lucia from El Salvador, Indochina I/CDC from Thailand, and Uganda Palo Alto) were inoculated into 38 monkeys. The results indicated that this species of Aotus monkey is highly susceptible to infection. The Uganda Palo Alto and the Santa Lucia strain parasites appear to be the most useful for immunologic and chemotherapeutic studies. Five strains of P. vivax (Chesson, ONG, Vietnam Palo Alto, Salvador I, and Honduran I/CDC) were inoculated into 28 monkeys. The Vietnam Palo Alto strain produced the highest level parasitemias ranging from 23,800 to 157,000/mm3. Mosquito infections were obtained with the ONG, Chesson, and Salvador I strains. Two out of 6 attempts to transmit P. vivax via sporozoite inoculation to splenectomized monkeys were successful with prepatent periods of 39 and 57 days. Five monkeys were infected with the Uganda I/CDC strain of P. malariae. Maximum parasitemias ranged from 10 to 5,390/mm3.

Animals↗

PubMed1988

Sporozoite-induced infections of the Salvador I strain of Plasmodium vivax in Saimiri sciureus boliviensis monkeys.

Twenty Saimiri sciureus boliviensis monkeys from Bolivia were inoculated intravenously with sporozoites of the Salvador I strain of Plasmodium vivax. All animals were splenectomized 7 days after inoculation. Inoculation of 100,000 sporozoites resulted in prepatent periods averaging 16.6 days; all monkeys developed high-level parasitemias with an average maximum of 103,000 per mm3. Inoculation of 10,000 sporozoites resulted in average prepatent periods of 19.4 days; one of the resulting infections produced a transient low-level parasitemia. Of 5 monkeys inoculated with 1,000 sporozoites, 4 had prepatent periods of from 24 to 35 days and 1 failed to demonstrate any parasitemia; 1 monkey supported a low-level transient parasitemia, whereas the other 3 monkeys had high-level parasitemias. It is proposed that by using a minimum inoculum of 10,000 sporozoites, the model system may be useful in the testing of anti-sporozoite vaccines directed against P. vivax.

Animals↗

PubMed1988

Transmission of the OS strain of Plasmodium inui to Saimiri sciureus boliviensis and Aotus azarae boliviensis monkeys by Anopheles dirus mosquitoes.

Eight Saimiri and 7 Aotus monkeys were exposed to infection with the OS strain of Plasmodium inui via the bites of from 2 to 7 Anopheles dirus mosquitoes. All Saimiri monkeys developed high-level infections of from 152,000 to 500,000/mm3 after prepatent periods of from 14 to 17 days. Only 1 Aotus monkey developed a patent infection after a period of 28 days. Feeding on these animals failed to result in infection of An. dirus mosquitoes.

Animals↗

PubMed1988

Instrument flight performance under the influence of certain combinations of antiemetic drugs.

Two different combinations of antiemetic drugs were evaluated using a digital flight simulator. Drug treatments consisted of a lactose placebo, a combination of thiethylperazine (10 mg) and cimetidine (300 mg), and a combination which added promethazine (25 mg) to the two-drug combination. The performance effects of these combinations were evaluated on both a dual task (instrument flight task with the Sternberg Memory Scanning task) and a single task condition (Sternberg task only) for 3 h post drug ingestion. Analysis indicated a significant treatment effect on three of the six flight performance variables and that the three-drug combination, containing promethazine, was primarily responsible for the decrease in performance. Implications for operation in a radiation environment are that thiethylperazine and cimetidine will not cause significant performance decrements, but the addition of promethazine to those two drugs will significantly impair performance. The Sternberg task was sensitive to changes in workload.

Adult↗