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R Lord

Publications and source records attributed to R Lord.

At least 19 recordsLinked to original sources
PubMed1992

Protective immunization with invariant peptides of the Plasmodium falciparum antigen MSA2.

Three octapeptides from the N and C terminal C regions of the merozoite surface Ag 2 (MSA2) of Plasmodium falciparum elicit anti-MSA2 antibody when given as diphtheria toxoid conjugates. These antibodies also bind to the MSA2 homolog from the rodent malaria Plasmodium berghei. All mice vaccinated with these conjugates and challenged with an otherwise lethal inoculum of P. berghei showed substantial protection with most surviving. There was a inverse correlation between the development of the parasitemia and the antibody titer, with alum, algammulin, and CFA giving comparable results. These observations show that the conserved region of MSA2 could form the basis of a malaria vaccine when presented in a suitably immunogenic form, thus avoiding the problems of antigenic diversity [corrected].

Adjuvants, Immunologic↗
PubMed1991

Humane killing.

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Anesthesia↗
PubMed1991

Ethanol euthanasia and its effect on the binding of antibody generated against an immunogenic peptide construct.

Mice were immunised with an immunogenic peptide construct CKNNNSTNSGI coupled to diphtheria toxoid as a carrier. This peptide sequence contains the epitope STNS which is the target of inhibitory monoclonal antibodies directed against the second merozoite surface antigen of Plasmodium falciparum. Antisera raised against the peptide construct were taken using an injection of 70 per cent ethanol or sodium pentobarbitone as methods of euthanasia and these methods compared by determining their effects on the binding specificity of the antibody to the antigen using the immunological criteria of immunofluorescence, immunoblotting criteria of immunofluorescence, immunoblotting and ELISA assays. There was no significant decrease in antibody binding with either sodium pentobarbitone, or ethanol with a final concentration of less than 30 per cent in mouse antisera. Antisera with an added ethanol concentration of 40 to 60 per cent relaxed antibody conformation and this raises the possibility of using the differential effects of ethanol as a tool in mapping antigenic fine structure of a range of antibodies directed against defined epitopes. The cross-reactive response of non-specific antibodies in polyclonal antisera was lowered at the suggested dosage for ethanol euthanasia. Ethanol has immense potential as an alternative method of euthanasia when barbiturate drugs, such as sodium pentobarbitone, are unavailable in specific experimental protocols. This may especially aid research workers in developing countries involved in vaccine development, antibody production and subsequent serological analysis.

Amino Acid Sequence↗
PubMed1991

Comparative immunogenicity of free and carrier-conjugated peptides derived from the constant regions of a polymorphic malarial surface antigen.

One peptide (L7) representing the entire constant N-terminal region, and two peptides (L5 and L6) representing the entire C-terminal constant region of the variable merozoite surface antigen MSA2, were synthesised by solid-state (tBOC) chemistry. Mice were immunised with the peptides alone and conjoined to the carrier protein diphtheria toxoid (DT) using the hetero-bifunctional reagent maleimidocaproyloxysuccinimide (MCS). Immune response was evaluated against the peptide itself by ELISA and against the intact protein MSA2 by immunoblotting and immunofluorescence assay (IFA). Whereas all peptides elicited a strong specific antipeptide response when administered as conjugates only L7 and L6 elicited an anti-peptide response in the absence of carrier. L5 and L7 conjugates elicited sera reactive with the intact MSA2, whereas only L7 elicited such specificity in the absence of carrier.

Amino Acid Sequence↗
PubMed1991

Immunological fine structure of the variable and constant regions of a polymorphic malarial surface antigen from Plasmodium falciparum.

The 51-kDa merozoite surface antigen MSA2 of Plasmodium falciparum shows considerable strain-dependent polymorphism. Although marked sequence variation occurs in the central region of the molecule, the N and C-terminal sequences are highly conserved. A number of monoclonal antibodies directed against MSA2 have been described which inhibit parasite growth in vitro, but these are all directed against variable regions. In an attempt to raise strain independent antibodies we have prepared peptide-diphtheria toxoid (DT) constructs from 36 N-terminal octapeptides spanning the constant region and extending into the variable region of the FCQ/27 PNG variant staggered by one amino acid at either end. Similarly, we prepared 26 C-terminal octapeptides spanning the C-terminal constant region as well as 10 octapeptides from the variable region of the Indochina I variant MSA2. Most of the peptides elicited antipeptide titres in excess of 1/10(4) when administered to mice as peptide-DT adducts emulsified with Freund's complete adjuvant. Only 3 of the 43 N- and C-terminal constant region peptides elicited antibodies which reacted appropriately on immunofluorescence (IFA) or immunoblotting analysis with the intact MSA2 of both strains studied (FCQ/27 and Indochina I), whereas 3 other peptides from the variable region elicited antibodies reactive with the parent MSA2 only. Peptide constructs eliciting antibodies recognising the intact protein corresponded to elements in the cognate sequence of high antigenicity as predicted by the Jameson and Wolf algorithm.

Amino Acid Sequence↗
PubMed1991

The metabolism of fibroblasts from normal and fibrotic skin is inhibited by minoxidil in vitro.

The effects of minoxidil in vitro were studied using fibroblasts grown from the lesional skin of patients with lichen sclerosus et atrophicus, morphoea and from the skin of normal individuals. The proliferation of all fibroblast lines over 3 days was inhibited in proportion to the concentration of minoxidil, being 20% or less of controls at 1 mM, where cell viability was only marginally reduced (84 +/- 2% vs. 88 +/- 2% (SEM) in controls). At 5 mM there was usually a net loss of cells and only 72% of those remaining were viable. In contrast, minoxidil at 0.1-1 mM stimulated the proliferation of foreskin keratinocytes by up to 130%. Contraction of collagen lattices containing the three types of fibroblasts was inhibited by 22-26% with 1 mM minoxidil after 5 days and by 50-94% with 5 mM. Secretion of glycosaminoglycans by normal fibroblasts showed concentration-dependent reduction, being 25 +/- 6% of that of untreated cultures with 1 mM minoxidil. These findings show that minoxidil has a range of inhibitory effects on both normal and abnormal skin fibroblasts in vitro, which contrast with its stimulation of skin epithelial cells, and support suggestions that it may provide a useful topical treatment for keloids and other fibroses.

Cell Division↗
PubMed1990

Synthetic peptide immunogens eliciting antibodies to Plasmodium falciparum sporozoite and merozoite surface antigens in H-2b and H-2k mice.

Peptides representing conserved (MSA2/1A and MSA2/1B) and variant (MSA2/2, MSA2/6 and MSA2/7) regions of the merozoite surface Ag 2 (MSA2) of Plasmodium falciparum (FCQ-27/PNG isolate) were coupled to either peptide NP(NANP)5NA or peptide C(NANP)6 both of which contained the core sequence (NANP)n. The coupling was done via the N-terminus of one peptide and a cysteine residue on either terminus of the other. BL/10 (H-2b) and B10.BR (H-2k) mice were immunized with these MSA2-(NANP)n conjugates. The mice were also immunized with the unconjugated MSA2 peptides and with NP(NANP)5NA and C(NANP)6. Antibody responses were evaluated by 1) ELISA, in which the MSA2 peptides and C(NANP)6 were used as Ag; 2) immunofluorescence assays (IFAT) against intact sporozoites and merozoites; and 3) immunoblotting experiments against solubilized P. falciparum blood stage proteins. High titer antibodies to (NANP)n were elicited in both BL/10 and B10.BR mice after immunization with all the conjugates except MSA2/7-(NANP)n which gave only a very limited response in B10.BR mice. These antibodies recognized unfixed sporozoites. The conjugates also elicited antibodies to MSA2 as shown by ELISA, IFAT, and immunoblotting except for mice immunized with MSA2/1B-(NANP)n where an anti-MSA2 response was only detectable by immunoblotting. Immunization with unconjugated MSA2 peptides showed that MSA2/2 was immunogenic in both BL/10 and BR.10 mice, with MSA2/6 and MSA2/7 being immunogenic only in BL/10 mice. The antibodies elicited recognized both merozoites and the MSA2 protein. However, the antibody titers were lower overall than those seen when these peptides were used in the conjugated form. No anti-MSA2 antibodies were detected after immunization with MSA2/1A and MSA2/1B. Immunization of mice with the peptide NP(NANP)5NA produced antibodies in BL/10 (H-2b) mice only, and the immunogenicity of this preparation was poor. In contrast, C(NANP)6 produced a strong antibody response in both mouse strains. The antibodies elicited by NP(NANP)5NA and C(NANP)6 recognised sporozoites in IFAT. The MSA2 peptides studied (or their derivatives) were previously shown to be recognized by human T cells. Their immunogenic potential shows promise in that complex anti-P. falciparum responses can be elicited with simple synthetic immunogens based on these peptides.

Amino Acid Sequence↗
PubMed1990

Peptide vaccines derived from a malarial surface antigen: effects of dose and adjuvants on immunogenicity.

Peptides P2122 (CKNNNSTNSGI) and P513 (CSQRSTNSAST) containing an epitope of a malarial surface antigen (MSA2) recognised by inhibitory monoclonal antibodies were conjugated to diphtheria toxoid (DT) protein and formulated with various gel-based and water in oil emulsion adjuvants in vaccine trials in mice and rabbits. The P2122-DT construct was effective in raising antibodies reactive with both the immunising peptide and the native antigen. Effective adjuvanticity as measured by the titre of the anti-peptide or anti-protein response in mice varied in the order: Algammulin, Montanide ISA 50 greater than or equal to Freund's adjuvant, Montanide ISA 708, 721, 70 much greater than alum, Squalene Arlacel greater than SAF-1. A similar order of adjuvant efficacy: Freund's greater than alum greater than Squalene Arlacel greater than SAF-1, was observed in rabbits.

Adjuvants, Immunologic↗
PubMed1990

Characterisation of an inhibitory monoclonal antibody-defined epitope on a malaria vaccine candidate antigen.

A monoclonal antibody that recognizes a recently characterised 45-kDa merozoite surface antigen of the human malaria parasite Plasmodium falciparum inhibits the growth of the asexual blood stages of the parasite in vitro. The corresponding epitope has been determined by testing the reactivity of the antibody with sequentially overlapping octapeptides. A synthetic peptide containing the epitope elicits antibodies that react with the native antigen. Epitope mapping in this manner is useful in the design of synthetic vaccines against malaria.

Amino Acid Sequence↗
PubMed1990

Fibroblast-keratinocyte interactions in psoriasis: failure of psoriatic fibroblasts to stimulate keratinocyte proliferation in vitro.

We have tested in two ways the hypothesis that dermal fibroblasts direct the hyperproliferation of the overlying epidermis in psoriasis. First, culture medium from psoriatic and from normal skin fibroblasts was added to monolayer cultures of foreskin keratinocytes. Second, psoriatic and normal fibroblasts embedded in hydrated collagen lattices were co-cultured with monolayers of foreskin keratinocytes. There was no evidence in either study that psoriatic fibroblast products could stimulate the proliferation of the keratinocytes, or that normal fibroblast products inhibited their proliferation. A positive control for the fibroblasts was provided by leucocyte supernatants, which stimulated keratinocyte proliferation by up to 65%. Our data do not support a primary role for dermal fibroblasts in psoriasis.

Cell Division↗
PubMed1989

Immune response to a synthetic peptide corresponding to an epitope of a parasitophorous vacuole membrane antigen from Plasmodium falciparum.

The parasitophorous vacuole membrane antigen QF 116 from Plasmodium falciparum contains a defined epitope, DNNLVSGP, proximal to the carboxyl-terminus which binds to the inhibitory monoclonal antibody 8E7/55. A synthetic peptide containing this epitope was constructed and coupled to diphtheria toxoid as carrier. Mice and rabbits were inoculated with this conjugate using CFA, SAF-1, or aluminum phosphate as adjuvants. The peptide conjugate was highly immunogenic in both animal species, giving rise to polyclonal antibodies with a similar epitope specificity as the original mAb. Antibody titers were dependent on the route of immunization. Rabbit antibodies produced in sufficient quantity for biologic assays inhibited parasite growth in vitro. This synthetic peptide thus shows promise as an immunogen for use in synthetic vaccine design.

Amino Acid Sequence↗
PubMed1989

Cross-reactivity of antibody against an epitope of the Plasmodium falciparum second merozoite surface antigen.

Monoclonal antibodies directed against the 51 kD merozoite surface antigen of Plasmodium falciparum also bind to other antigens within the infected cell. The sizes of these cross-reacting antigens have been characterized. Immunofluorescence due to the reaction of one of the monoclonal antibodies with these cross-reacting antigens was localized in the intra-erythrocytic parasite and in granules in the infected red cell cytoplasm. This immunofluorescence could be distinguished from the merozoite surface antigen in parasite lines with a variant serotype of the merozoite surface antigen which fails to react with the monoclonal antibodies. It was found that the in-vitro growth inhibition caused by the presence of one of the monoclonal antibodies, 8G10/48, was dependent on the expression of the corresponding serotype of merozoite surface antigen, a finding consistent with the inhibitory effect of this antibody being primarily directed against the merozoite surface antigen and not the cross-reacting antigens. Analysis of the frequency at which epitopes occur suggests that such cross-reacting proteins will be commonly seen in malaria, without the need to postulate a selective advantage for such cross-reacting specificities.

Animals↗
PubMed1989

Assessment of neutrophil function: an introduction.

Normal neutrophil function depends on the integration of chemotaxis, phagocytosis, degranulation and oxidative metabolism. As congenital and acquired neutrophil abnormalities increase the risk of infection, frequently with no other diagnostic features, diagnosis depends upon specialist laboratory investigations. Techniques for quantitative evaluation of the principal neutrophil functions are discussed, and a preliminary screening programme for neutrophil abnormalities proposed.

Cell Adhesion↗
PubMed1989

Skin test studies on close contacts of leprosy patients in India.

Skin-test studies with a series of tuberculins have been carried out in close contacts of multibacillary (MB) leprosy patients around three leprosy centers in India, and casual contacts of the disease around two centers. The results show that the rate of acquisition of leprosin A positivity is associated with age and the closeness of contact with MB leprosy. At the age of 15 years, the differences between the two types of contact were highly significant (p less than 0.00001). Many responses to leprosin A are directed toward the group iv species-specific, antigens of the leprosy bacillus, and the significance of positivity is discussed in relation to protective immunity from leprosy. The differences from Iran show that positivity to leprosin A is not solely the effect of the degree of contact with the disease, but must also have a genetic or environmental element, the latter being favored. The results from Miraj show that the high levels of tuberculin, scrofulin, and vaccin positivity seen in Fathimanagar, and to a lesser extent in Karigiri, are not a consequence of contact with leprosy. BCG vaccination made little difference to the leprosin A positivity of close contacts of leprosy patients, although it significantly enhanced positivity among casual contacts around Miraj (p less than 0.002). BCG vaccination significantly increased tuberculin positivity in Miraj and Karigri, and in those under 11 years of age in Fathimanagar. It made no difference to the already high level of positivity found in older persons around Fathimanagar.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Patterns of rotary pursuit performance in clumsy and normal children.

The present study is concerned with the development of motor programs in clumsy children. In order to investigate this, the performance of clumsy and normal children on a rotary pursuit tracking task was compared. The performance of the clumsy group was inferior to that of the control group in terms of time on target, but the pattern of performance across successive trials was broadly similar for the two groups, suggesting a progression from control by visual feedback to control by motor programs. It was concluded that the performance of clumsy children on the rotary pursuit task may be limited more by impaired visual feedback control than by an impairment in the ability to develop motor programs.

Attention↗