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Biomedical subjects

M G Taylor

Publications and source records attributed to M G Taylor.

150 records · Page 9Linked to original sources
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Immunization of baboons with attenuated schistosomula of Schistosoma haematobium: levels of protection induced by immunization with larvae irradiated with 20 and 60 krad.

We have shown previously that baboons (Papio anubis) develop high levels (greater than 80%) of protection against challenge infection following immunization with Schistosoma haematobium cercariae irradiated with 20 krad. In the present study baboons were immunized with schistosomula irradiated with either 20 krad or 60 krad, with variations in the timing and number of larvae comprising each vaccination. Baboons immunized 2 or 3 times with schistosomula irradiated with 20 krad were significantly more protected (85-90%) against challenge infection than baboons similarly immunized with larvae receiving 60 krad (56-50% protection). Baboons immunized with schistosomula irradiated with 20 krad were better protected against challenge infection at 8 weeks after immunization than at 28 weeks after immunization. Protection was manifest by a reduction in worm numbers, tissue and excreta egg counts, gross pathology and, to a lesser extent, by stability of body weight and haematological indices following challenge. Enzyme-linked immunosorbent assay (ELISA) results of selected baboon sera showed few differences related to irradiation dose alone, but titres were higher in baboons receiving booster immunizations, and there was a significant correlation between titres immediately preceding challenge and the degree of resistance. Examination of responses to individual schistosomular surface antigens by immunoprecipitation and sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed no correlation between the pattern of antigens recognized and resistance status. As with the ELISA assay, an anamnestic response was detected after vaccination, while the amount of antibody present declined markedly with increasing time after individual immunizations.

Animals↗
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Diagnosis of Schistosoma haematobium infection: evaluation of ELISA using keyhole limpet haemocyanin or soluble egg antigen in comparison with detection of eggs or haematuria.

Keyhole limpet haemocyanin (KLH) was compared with Schistosoma haematobium soluble egg antigen (SEA) in the enzyme-linked immunosorbent assay (ELISA) for detection of S. haematobium infection, using 187 human sera collected from the S. haematobium endemic area of Pemba Island, Tanzania, and 30 normal sera from blood donors in Europe. There was a clear separation in terms of immunoglobulin (Ig) G and IgM titres between parasitologically positive patients and the blood donors, but titres of many parasitologically negative individuals in the endemic area were significantly high in comparison with the normal controls. Using as cut-off point the mean optical density +2 SD of sera from the blood donors to define ELISA positivity, and comparing the results with urine egg counts, the sensitivity of IgG-ELISA using KLH or SEA was high (91.11% and 95.56%, respectively) but the specificity was poor (43.30% and 31.90%, respectively. Similar results were obtained with IgM. When the 'gold standard' of haematuria and/or egg positivity as indicative of infection was used, the sensitivity of the ELISAs was similar but the specificity was increased to 59.25% and 44.44%, respectively. These results suggest that the patients with haematuria were probably infected with S. haematobium, which further supported the diagnostic value of haematuria detection for S. haematobium infection in endemic areas, and KLH was found to have a potential use in immunodiagnosis of S. haematobium infection in endemic areas. With both KLH and SEA antigens, the trend of reactivity in ELISA provided a correlate of the egg output (parasite burden) of infected patients.

Animals↗
PubMedDate not supplied

A combined ultrasonic linear array scanner and pulsed Doppler velocimeter for the estimation of blood flow in the foetus and adult abdomen--I: Technical aspects.

A method is proposed for estimating the volume blood flow of deep lying vessels in the foetus and in adult portal vein and renal vessels. The equipment combines a 3.5 MHz linear array scanner with a 2 or 4 MHz pulsed Doppler. The pulsed Doppler tranducer is connected to the linear array by two movable arms. A real time spectrum analyser is used to process the Doppler signals. A water bath was used to perform an in vitro calibration of the complete system and to adjust the registration of the Doppler sample volume with the echo picture. Several possible inaccuracies in vessel diameter measurement are discussed and the mean of several caliper measurements described by Eik-Ness (1982) is used. Time Motion is thought to be the better method but is more complicated in practice.

Adult↗
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Subcellular distribution of cadmium and its cellular ligands in mussel digestive gland cells as revealed by combined autometallography and X-ray microprobe analysis.

Autometallography (AMG) and electron probe X-ray microanalysis (EPXMA) were applied in combination to determine the subcellular distribution of Cd and its subcellular ligands in the digestive gland cells of Cd-exposed mussels Mytilus galloprovincialis. Black silver deposits (BSD), which reveal the presence of metals when AMG is applied, were only localized in digestive cell lysosomes. Digestive cell cytoplasm and basophilic cells were devoid of BSD. EPXMA (static probe and X-ray mapping) indicated that Cd, S (possibly associated with metallothioneins or metallothionein-like proteins) and autometallographical Ag ions are co-localized within digestive cell lysosomes. In addition, Cd and S co-occur in the absence of Ag in the cytosol of digestive cells. AMG does not reveal the presence of the Cd 'pool' strongly bound to cytosolic Cd-metallothionein complexes; only 'free' Cd or Cd supposedly loosely bound to (semi)digested metallothionein within lysosomes was revealed. The levels of lysosomal Cd were indirectly quantified by stereology as the volume density of BSD (V(v)BSD). Significantly higher values were recorded in Cd-exposed mussels compared with controls at all exposure times. However, V(v)BSD values were lower at days 7 and 21 than at day 1. This relative decrease in V(v)BSD reflected another (and confounding) response elicited by Cd-exposure in the digestive epithelium: the volume density of basophilic cells (V(v)BAS) increased significantly as exposure progressed. Due to this cell-type replacement, the net accumulative capacity of the digestive epithelium decreases at long exposure times.

Animals↗
PubMedDate not supplied

Gene cloning, expression and vaccine testing of Schistosoma japonicum SjFABP.

A 600 bp DNA fragment was amplified by PCR from an adult Schistosoma japonicum cDNA library. Sequence analysis confirmed that this fragment contained an S. japonicum Chinese mainland strain fatty acid binding protein (Sj14FABP) gene. This gene was subsequently expressed in Escherichia coli (E. coli) and in Baculovirus/silkworm systems. The recombinant protein from E. coli was a 41 kDa GST fusion protein (rSj14/GST), which could be purified by glutathione agarose affinity chromatography, with a yield of 25 mg/L E. coli culture. The recombinant protein from the Baculovirus/silkworm system was an 18 kDa fusion protein (rSj14/His), which could be purified by Ni-NTA resin chromatography column with a yield of 3.5 mg per silkworm larva. Both rSj14/GST and rSj14/His could be recognized by S. japonicum-infected mouse sera and anti-rSj14/GST mouse sera in Western blotting. The purified recombinant protein was immunogenic in mice, rats and sheep, and 34.3%, 31.9% and 59.2% worm reductions, respectively, were obtained in vaccinated Kunming mice, Wistar rats and sheep vaccinated with Sj14/GST, compared to non-vaccinated control groups. Worm reductions of 48.8% and 49.0% were recorded in Balb/c mice immunized with Sj14/His, compared to non-vaccinated and BCG-vaccinated groups, respectively. These results indicate that rSj14FABP is a promising candidate vaccine for schistosomiasis japonica, particularly as in the rat and sheep vaccination experiments, no adjuvant was used.

Amino Acid Sequence↗