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Biomedical subjects

C J Shiff

Publications and source records attributed to C J Shiff.

At least 37 records · Page 2Linked to original sources
PubMed1994

A chemokinetic response in Schistosoma mansoni cercariae.

Schistosoma mansoni cercariae have been shown to aggregate in the presence of glass slides treated with clear nail varnish and linoleic acid. In choice chambers cercariae move toward the stimulant, but this behavior is not seen when linoleic acid is omitted. After 30-45 min, the cercariae were concentrated near the end of the choice-chamber containing the linoleic acid slide. When the cercariae were added in the center of the choice chamber, they formed a diffuse cloud that dispersed slowly in both directions in the absence of linoleic acid. Cercariae aggregating in the vicinity of a stimulant surface are not immediately stimulated to commence penetration; this appears to be time and dose related.

Animals↗
PubMed1994

Extraction of Haemoproteus columbae (Haemosporina: Haemoproteidae) antigen from rock dove pigeons (Columba livia) and its use in an antibody ELISA.

Erythrocytic stages of Haemoproteus columbae were extracted from the cytoplasm of nucleated red blood cells (RBC) of Rock dove pigeons (Columba livia) using cationic detergent (N,N',N'-polyoxyethylene(10)-N-tallow-1,3-diaminopropane [EDTA-20]) and discontinuous Percoll gradient density. Crude RBC extract (CRBCE) antigen was prepared. Parasitized RBCs were more resistant to EDTA-20 action than unparasitized cells. An enzyme-linked immunosorbent assay (ELISA) was developed for detection of anti-H. columbae immunoglobulins in 30 wild-captured C. livia. Whole blood, serum, and dried blood on filter paper gave similar results; the latter was selected for sampling convenience. Optimal antigen concentration was 5 micrograms/ml, and anti-H. columbae immunoglobulins were detectable at a 10(-4.11) dilutions. The binding efficacy of anti-chicken IgG to the pigeon immunoglobulins was significantly higher than anti-duck IgG or anti-turkey IgG. Parasitemia by Giemsa-stained thin blood smears ranged from 20.0 to 47.5%, mean = 32.4 +/- 8.3%; 17 of 30 birds had multiply infected RBCs with a mean parasitemia of 2.4 +/- 1.1%, range 0.7-4.9%; 27 birds were positive by the ELISA. No clinical signs of infection were observed. ELISA absorbance values were not correlated with the level of parasitemia in individual birds. All pigeons were negative for anti-Plasmodium relictum and anti-P. elongatum immunoglobulins as determined by ELISA. The pigeons were not subclinically infected with Plasmodium spp. as determined by inoculation of domestic ducklings with blood from dexamethasone-immunosuppressed pigeons.

Analysis of Variance↗
PubMed1994

Chloroquine resistant Plasmodium falciparum in coastal Tanzania. A challenge to the continued strategy of village based chemotherapy for malaria control.

An in vivo study to assess Plasmodium falciparum sensitivity to chloroquine was conducted in two villages of the Bagamoyo District, Tanzania in December 1992. The WHO standard field test (7 days) and the extended test (28 days) were carried out on symptom free children. The presence of chloroquine resistance was confirmed with 59% of infections being found resistant. Fifty-three percent were RI, 2% were at RII and 4% at RIII levels of resistance. Dosage was 25 mg/kg chloroquine base delivered over three days.

Animals↗
PubMed1993

Experimental infection of domestic ducks and rodents by Notocotylus attenuatus (Trematoda: Notocotylidae).

In order to study transmission patterns of Notocotylus attenuatus five 3-wk-old domestic ducks, five 8-wk-old rats and ten 4-wk-old mice were infected with the parasite. All ducks became infected and all flukes were recovered from the intestinal ceca. Worms moved down the length of the cecum during development and as the parasites grew they changed their method of attachment. Flukes became gravid by day 16 post-infection, after which growth ceased. Egg filaments appear to play a role in the formation and movement of worm egg clusters from the distal portion of the cecum to the lumen of small intestine. Rodents also became infected with the parasite producing granulomatous nodular lesions in the lower small intestine but all flukes in the granulomata were dead. It is unlikely that transmission of this trematode can depend on mice and rats.

Animals↗
PubMed1993

ELISA method for detecting anti-Plasmodium relictum and anti-Plasmodium elongatum antibody in infected duckling sera using Plasmodium falciparum antigens.

An enzyme-linked immunosorbent assay (ELISA) with 3 Plasmodium falciparum NF-54 antigens, R32tet32, P.F.R27, and crude red blood cell extract (CRBCE), was tested for detection of anti-Plasmodium relictum and anti-Plasmodium elongatum antibodies in sera from experimentally infected ducklings. Whole blood, serum, and dried blood on filter paper gave similar results. The latter was selected for convenience. All birds infected by experimental blood challenge, but not exposed to sporozoites, had detectable antibody (up to 1.0 x 10(-3.8) dilution) reactive with R32tet32, P.F.R27, and CRBCE antigens. Ducklings infected with P. elongatum had higher antibody levels than those infected with P. relictum. In a blind trial, the described ELISA accurately distinguished sera taken from infected and uninfected ducklings. This study provides the first evidence on cross reactivity in the ELISA format between P. falciparum antigens and antibodies induced by P. relictum and P. elongatum in experimentally infected ducklings. The proposed ELISA is fast, easy to perform, reproducible, and requires a minimal amount of equipment. The assay can be used for the detection of P. relictum and P. elongatum antibodies in captive or wild ducks, along with monitoring the level of antibody in selected groups of birds or for surveys of laboratory experiments where evidence of infection is required.

Animals↗
PubMed1993

A trap for the detection of schistosome cercariae.

A simple trap for schistosome cercariae has been developed using clear nail varnish as a matrix and linoleic acid as stimulant affixed to a 75 x 25-mm glass slide. Schistosoma mansoni cercariae will attach to the surface and easily can be visualized either stained or unstained. The trap works well under laboratory and field conditions where the retrieval rate varies from 30% to 100%. Under laboratory conditions there appears to be some form of affinity for cercariae to the surface.

Animals↗
PubMed1993

Excystment in vitro of Cotylurus cornutus (Trematoda: Strigeidae) metacercariae.

An acid-medium pretreatment appeared to be essential for in vitro excystation of Cotylurus cornutus metacercarial cysts. Both acid-pepsin or acid-saline were effective but optimum excystation occurred after 15 min acid-pepsin pretreatment and subsequent 2 hr treatment at 41.5 C in an alkaline bile salt-trypsin medium. The rate of excystation was rapid, reaching 78.1% by 1 hr and increasing to 84.3% after 2 hr. Storage of metacercarial cysts up to 16 wk at 4 C in sterile Locke's 1:1 solution did not alter cyst viability.

Animals↗
PubMed1992

Schistosoma mansoni: cercaricidal effects of cedarwood oil and various of its components.

Cercariae of Schistosoma mansoni exposed to cedarwood oil show early phases of the penetration response before they succumb to the toxic effects of the oil. The toxic effect is also seen when cercariae are exposed to certain components of the oil followed by exposure to a known penetration stimulant, linolenic acid, which accelerates the inactivation of the organism. It is postulated that the process of penetration which results in the disruption of the cercarial glycocalyx alters physiological processes related to osmoregulation. This may increase the absorption of the toxic substances in cedarwood oil by the organisms.

Animals↗
PubMed1991

Ecdysteroids as regulators of host and parasite interactions: a study of interrelationships between Schistosoma mansoni and the host snail, Biomphalaria glabrata.

Ecdysteroids have been detected in trematode parasites and in several species of gastropod snails. The potential role of these and other hormones as regulators of host/parasite interactions is discussed. This study considers the role of ecdysteroids in the host parasite interactions between Schistosoma mansoni and Biomphalaria glabrata interactions. beta-Ecdysterone was found to be effective in stimulating host location activities in S. mansoni miracidia and in enhancing growth and egg production in B. glabrata. However, plant extracts rich in phytoecdysteroids were not attractive to miracidia and did not affect growth and egg production in snails. The potential role of ecysteroids in the process of parasitism and snail physiological processes is discussed. Plants rich in phytoecdysteroids do not appear to be of value in process which may interfere with the host parasite interactions in schistosomes.

Animals↗
PubMed1989

Immunological effects of HIV-1 infection on the humoral response to malaria in an African population.

We conducted a cross-sectional study to determine the serological response to malaria in an HIV-1 infected population and in a control population in a region of high malaria transmission. The study group consisted of 66 hospitalized patients with clinical acquired immunodeficiency syndrome (AIDS) and 70 trauma patients without clinical AIDS (controls). Mean optical densities of antibody produced against RESA-4, RESA-8, RESA-11, (PNAN)5 and (NAAG)5 synthetic peptides of Plasmodium falciparum were compared between HIV-1 seropositive and HIV-1 seronegative patients using non-parametric statistics. HIV-1 seropositive patients with clinical AIDS had significantly less antibody to the synthetic P. falciparum ring stage peptide, RESA-8 (P = 0.001), than a comparable group of seronegative patients. Antibody levels were also low for the other ring stage peptides, RESA-4 (P = 0.024) and RESA-11 (P = 0.024). Although not statistically significant, antibody levels among the HIV-1 seropositive trauma patients were higher than among the HIV-1 seronegative trauma patients. During HIV-1 infection, a polyclonal B cell activation may occur as noted in the HIV-1 seropositive trauma patients, but with increased immunosuppression in advanced clinical AIDS, B cell stimulation appears to be diminished. This results in decreased production of malaria antibody.

Acquired Immunodeficiency Syndrome↗
PubMed1979

Seasonal patterns in the transmission of Schistosoma haematobium in Rhodesia, and its control by winter application of molluscicide.

Surveys of snails occurring at water contact points used by rural people in Rhodesia show that transmission of Schistosoma haematobium is very high during the spring and early summer seasons. Although infected snails are found in all seasons, fewest occur in winter and during the heavy rains. It is suggested that the bionomics of this parasite depends on pre-rain transmission because destruction of infected snails during winter reduces the reservoir of infection in the area and also the level of parasitaemia in local schoolchildren.

Adolescent↗
PubMed1976

The use of serology by titering of fluorescent antibodies to evaluate levels of transmission of schistosomiasis in Rhodesia.

The prevalence of schistosomiasis has been measured by parasitological examination and by fluorescent antibody titering in a number of communities in different parts of Rhodesia. The samples were taken from areas of high, medium, and low transmission of the disease. A correlation was detected between the mean titer and prevalence of infection, particularly in the younger people (4-13 years old). It is suggested that fluorescent antibody titrating may be a useful epidemiological tool.

Adolescent↗