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Biomedical subjects

M T Rogan

Publications and source records attributed to M T Rogan.

At least 37 records · Page 2Linked to original sources
PubMed1996

Echinococcus granulosus antigen B and seroreactivity in natural ovine hydatidosis.

Hydatid cyst fluid from sheep and camels infected with Echinococcus granulosus, together with partially purified preparations of hydatid fluid antigen B and a recombinant antigen B product, were tested in an ELISA for their ability to detect IgG antibodies against E granulosus in the serum of naturally infected sheep. The antibody activity in sera from sheep naturally infected with Taenia hydatigena cysticercosis or Fasciola hepatica was also tested. All the antigen preparations from native hydatid cyst fluid were able to detect antibodies in the sera from a significant proportion of sheep with natural hydatid cyst infection, as identified by inspection at slaughter, although the seroreactivity was variable. The native antigen B preparation from camel hydatid cyst fluid gave the highest sensitivity in the ELISA (total 90 per cent), with 99 per cent specificity. In all cases, the recombinant antigen B was the least sensitive antigen (25 per cent) although it was highly specific (99 per cent).

Animals↗
PubMed1995

LTP is accompanied by commensurate enhancement of auditory-evoked responses in a fear conditioning circuit.

Transmission of auditory information from the medial geniculate body to the lateral nucleus of the amygdala is believed to be involved in the conditioning of fear responses to acoustic stimuli. This pathway exhibits LTP of electrically evoked field potentials after high frequency stimulation of the medial geniculate body. High frequency stimulation of the medial geniculate body also results in a long-lasting potentiation of a field potential in the lateral amygdala elicited by a naturally transduced acoustic stimulus. This demonstrates that natural information processing can make use of the physiological mechanisms set in motion by LTP induction.

Amygdala↗
PubMed1995

Immunoblot evaluation of IgG and IgG-subclass antibody responses for immunodiagnosis of human alveolar echinococcosis.

Antigen binding of total-IgG and IgG-subclass antibodies from patients with alveolar or cystic echinococcosis (AE and CE) was assessed by immunoblotting. Antigen extracts were prepared from Echinococcus multilocularis protoscoleces (EmP) or from homogenized E. multilocularis metacestode tissue (EmCH). Antigens of approximately 44, 35, 21, 17.5 and 16.5 were recognized by total-IgG and IgG1- and IgG4-subclass antibodies in some of 50 human AE sera from China, Japan or France. The 44- and 35-kDa polypeptides, present in both EmP and EmCH extracts, were recognized by total-IgG antibodies in sera from 82% and 66% of the AE patients, respectively. However, over 30% cross-reactivity occurred between these two antigens and sera from CE and Taenia solium cysticercosis patients. The immunoblot specificities of the 27-, 21- and 17.5-kDa antigens in EmP for E. multilocularis infection were 73%, 88% and 93%, respectively. Recognition of the 17.5-kDa antigen in the EmP immunoblot was much higher for the Japanese AE cases (11/13; 85%) than for the French (9/19; 47%) or Chinese (9/18; 50%) AE cases. None of the CE cases from Uruguay or Libya, where human AE has not been reported, was seropositive for the 17.5-kDa antigen. Antibodies from three (7.3%) of the 41 Chinese CE cases recognized the 17.5-kDa antigen. Within the 13 Japanese AE sera, the combined detection by IgG1, IgG4 and total-IgG antibodies of the 27-, 21- and 17.5-kDa antigens in either EmP or EmCH immunoblots was greater than that by each class/subclass alone, increasing the overall sensitivity for AE patients. A combined ELISA/immunoblot approach, including IgG-subclass detection using E. multilocularis protocolex or cyst extracts, could be useful for the differential diagnosis of human alveolar echinococcosis. An algorithm for such an approach is given.

Algorithms↗
PubMed1994

Serotoninergic and peptidergic nerve elements in the protoscolex of Echinococcus granulosus (Cestoda, Cyclophyllidea).

The localisation and distribution of 5-hydroxytryptamine (5-HT, or serotonin) and neuropeptides in the nervous system of the protoscolex of the hydatid organism Echinococcus granulosus were determined by an indirect immunofluorescence technique. Nerve-cell bodies immunoreactive for 5-HT occurred in the lateral ganglia and in association with the lateral longitudinal nerve cords. 5-HT immunostaining was also evident in the central nerve ring, in the rostellar nerves and in the nerve plexus innervating the suckers. Of the antisera used to screen the protoscolex for neuropeptide immunoreactivity (IR), immunostaining was obtained with those raised against pancreatic polypeptide (PP), peptide YY (PYY), substance P (SP), peptide histidine isoleucine (PHI) and vasoactive intestinal peptide (VIP). The most extensive pattern of IR occurred with antisera to PP and PYY. Immunoreactive nerve elements were evident in the lateral ganglia, central nerve ring, rostellar nerves, rostellar ganglia, sucker plexus and longitudinal nerve cords. The distribution of SP-, PHI- and VIP-IRs was more restricted: SP-IR occurred in the lateral ganglia and sucker nerves, whilst PHI- and VIP-immunoreactive nerve elements were associated with the lateral longitudinal nerve cords. Protoscoleces cultured in vitro for 29 days were also examined and neuroanatomical changes noted. A greater development of the longitudinal nerve cords and their cross-connectives in the body of the worm was evident, and a group of nerve cells were seen to develop at the posterior end of the main lateral nerve cords.

Animals↗
PubMed1994

Immunocytochemical localization of serotonin (5-HT) in the nervous system of the hydatid organism, Echinococcus granulosus (Cestoda, Cyclophyllidea).

The localization and distribution of the serotoninergic components of the nervous system in the hydatid organism, Echinococcus granulosus, were determined by immunocytochemical techniques in conjunction with confocal scanning laser microscopy (CSLM). The distribution of serotonin immunoreactivity (IR) paralleled that previously described for cholinesterase activity, although it was more widespread. Nerve cell bodies and nerve fibres immunoreactive for 5-HT were present throughout the central nervous system (CNS), occurring in the paired lateral, posterior lateral and rostellar ganglia, their connecting commissures and nerve rings in the scolex and in the ten longitudinal nerve cords that run posteriorly throughout the body of the worm. A large population of nerve cell bodies was associated with the lateral nerve cords. In the peripheral nervous system (PNS), immunoreactive nerve fibres occurred in well-developed nerve plexuses innervating the somatic musculature and the musculature of the rostellum and suckers. The genital atrium and associated reproductive ducts were richly innervated with serotoninergic nerve cell bodies and nerve fibres.

Animals↗
PubMed1993

The potential of vervet monkeys (Cercopithecus aethiops) and baboons (Papio anubis) as models for the study of the immunology of Echinococcus granulosus infections.

Nine vervet monkeys and nine baboons were infected with eggs of Echinococcus granulosus per os. Six of the vervets and one of the baboons possessed hydatid cysts at autopsy, 15-28 months post-infection. The sequential IgG response to hydatid fluid and protoscolex antigens showed considerable inter-animal variation. Infected vervets and baboons became seropositive after an average of 8 months post-infection. Considerable fluctuation in the IgG response was observed, particularly to the hydatid fluid antigen which, in humans, may contribute to the existence of a significant proportion of seronegative individuals. Vervets, in particular, may be useful to study immunological events associated with exposure, development and resolution of hydatid disease in outbred human populations.

Animals↗
PubMed1991

Necator americanus secretory acetylcholinesterase and its purification from excretory-secretory products by affinity chromatography.

Acetylcholinesterase (AChE) secretion by adult N. americanus was enhanced in vitro by incorporating insoluble collagen rafts into culture dishes. Enzyme produced in this way had preferential substrate specificity for acetylthiocholine iodide (ATC), and its activity was inhibited by eserine (1.1 x 10(-8) M). Ancylostoma ceylanicum, another hookworm species, failed to produce comparable amounts of AChE in culture. AChE was efficiently purified from culture medium by affinity chromatography on edrophonium sepharose; 81% of the AChE activity was retained by the affinity matrix, although this fraction contained only 4.3% of the protein loaded. Antisera raised against purified AChE in rabbits immunohistochemically stained the oesophageal glands of the parasite, and reacted with molecules of 32, 60, 80, 140 and 220 kDa in reduced adult ES products on Western blotting, although differential activity was observed against worm homogenates and earlier developmental stages. On IEF, purified AChE resolved predominantly with a pl of 3.55; proteins with a similar pl were recognized by rabbit anti-AChE. IgG preparations of this antiserum inhibited AChE activity in ES products, and inhibited AChE secretion by adult worms in culture. The availability of this immunological probe will allow definitive experiments to be conducted on the role of this enigmatic enzyme in the host-parasite relationship.

Acetylcholinesterase↗
PubMed1990

Echinococcus granulosus: the potential use of specific radiolabelled antibodies in diagnosis by immunoscintigraphy.

Diagnosis of hydatid disease in man is frequently dependent on the imaging of cysts in situ by techniques such as ultrasonography and CAT scans. Such methods are useful but are not specific and can lead to errors in diagnosis. The present work reports preliminary experiments on the development of a specific imaging technique for hydatid cysts using radiolabelled antibodies. A purified preparation of antigen B of hydatid fluid was used to raise polyclonal antisera in rabbits and the resulting affinity-purified IgG labelled with 131I. Gerbils with an established Echinococcus granulosus infection were injected intraperitoneally with the labelled antibody and imaged 48 h later with a gamma camera. Hydatid cysts could be identified within the peritoneal cavity and post-mortem assessment of activity showed the cysts to contain approximately four times as much activity as the surrounding organs thereby indicating successful targeting of the antibody to the cysts.

Animals↗
PubMed1990

The identification of a species-specific antigen from Necator americanus.

A 17 kD protein of Necator americanus was isolated by SDS-PAGE and used to raise monospecific antisera in rabbits. ELISA and Western blotting against a range of parasite extracts demonstrated the species specificity of this protein. It is expressed at all stages of the life-cycle, appears to be accumulated through the larval stages to adulthood, and can be localized in the oesophageal glands and cuticle of the adult parasite. The possible nature and diagnostic potential of this protein is discussed.

Animals↗
PubMed1989

Development of the tegument of Echinococcus granulosus (Cestoda) protoscoleces during cystic differentiation in vivo.

During the first 4 days following infection, early tegumentary changes are confined to the protoscolex soma of Echinococcus granulosus, the thick glycocalyx being lost and the blunt elevations, flattened. The Golgi complexes within the tegumentary cytons produce T2 vesicles that increase in number in the tegument from days 4 to 12, whereas T1 vesicles decline. Spineless, truncated microtriches develop at the somal surface, and the laminated layer starts to form around the developing cyst from days 20-40 onwards. T2 vesicles do not appear to be involved in its formation and decline in number. Two additional vesicle types participate in the production of the laminated layer: T4 vesicles contribute to the carbohydrate matrix, and 'G' vesicles form granular accumulations. Cystic differentiation is completed after 2-3 months, when the spined microtriches and rostellar hooks of the scolex are shed into the laminated layer and replaced by truncated microtriches. These ultrastructural changes are discussed with respect to parasite survival.

Animals↗
PubMed1988

Cuticle preparations from Necator americanus and their immunogenicity in the infected host.

Cuticle samples have been prepared from the human parasitic nematode Necator americanus using detergent solubilisation with sodium dodecyl sulphate and subsequent reduction of disulphide bonds using 2-beta-mercaptoethanol. It would appear that N. americanus, like many other nematodes, relies on relatively small collagenous proteins, linked by disulphide bonds, to maintain the integrity of its cuticle. These molecules are normally hidden from the immune system during the course of infection but are potentially immunogenic. It is suggested that waves of antibodies, firstly with specificity against superficial cuticular epitopes followed by antibodies against deeper lying, structural elements, should be induced during vaccination to effectively destroy the nematode at the cuticular level.

Animals↗
PubMed1987

Echinococcus granulosus: changes in the surface ultrastructure during protoscolex formation.

Changes in the tegumentary projections of protoscoleces of Echinococcus granulosus, developing within brood capsules, were examined at the ultrastructural level. The original scant covering of spineless, truncated microtriches was supplemented by a population of microvilli covering the entire surface of protoscoleces in the early stages of formation. As differentiation continued, rostellar hooks were formed by enlargement of single large (T1) microtriches, and normal spined microtriches were produced on the sucker region. These were formed in two ways: by addition of spine material to the truncated microtriches, and de novo followed by up-lifting from the tegumentary surface. A second type of large microthrix (T2) was present in a band immediately below the developing hooks. These microtriches appeared to be formed from a fusion of existing microtriches, but were subsequently lost prior to scolex invagination. The microvilli were also shed from both the sucker and soma regions, to be replaced by microtriches and small blunt elevations respectively.

Animals↗
PubMed1986

Echinococcus granulosus: in vitro effect of monensin on the tegument of the protoscolex.

Protoscoleces of Echinococcus granulosus were incubated in a 10 microM solution of monensin and their viability and the ultrastructure of their tegument were monitored over a 36 h period. The earliest effects of the ionophore, apparent within 15 min, involved a degree of cisternal swelling of the tegumentary Golgi complexes. Swelling became more pronounced with time and cytons eventually contained numerous large electron-lucent vesicles. Residual bodies indicative of autophagy were observed in the cytons and distal cytoplasm from 1 h onwards. All movement of protoscoleces ceased after 1 h and the surface of the soma subsequently became folded, possibly suggesting spastic paralysis. Later, vacuoles and large cytoplasmic blebs were observed in the distal cytoplasm and viability dropped rapidly after 12 h. All protoscoleces were dead at 36 h. The potential of monensin as an in vivo protoscolicidal agent is discussed.

Animals↗