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Biomedical subjects

E Griffiths

Publications and source records attributed to E Griffiths.

At least 19 recordsLinked to original sources
PubMed1995

Haemoglobin-based blood substitutes and sepsis.

An important concern that has received little attention is the possible increased susceptibility to bacterial infections of patients infused with cell-free haemoglobin-based blood substitutes. We show that pyridoxalated polymerised human haemoglobin promotes fulminating Escherichia coli septicaemia in mice, which draws attention to the potential danger of such products in the clinic.

Animals↗
PubMed1994

Reduction of virus shedding by B. bifidum in experimentally induced MRV infection. Statistical application for ELISA.

The protective effect of a human strain of Bifidobacterium bifidum (B. bifidum) against murine group A rotavirus (MRV) was examined in the intestines of BALB/c infected mice. In experiments designed to determine whether B. bifidum mediated MRV shedding during diarrheal disease, pregnant dams (and their expected litters) were randomly assigned to the following groups: (1) mice infected with MRV alone; (2) B. bifidum-treated + MRV-infected mice; (3) B. bifidum-treated controls; and (4) saline control animals. An enzyme-linked immunosorbent assay (ELISA) for the detection of group A rotavirus was used to measure virus protein. The sensitivity of the MRV antigen detector ELISA was determined by serially diluting the rotavirus antigen in test samples. Antigen was detected in dilution ranges of 1:256-1:4096 during the acute phase and 1:16-1:512 in the recovery phase of MRV clinical disease, in the samples tested. Treatment with B. bifidum significantly reduced shedding of MRV antigen (P < 0.009) on days 2-10 postinoculation. The reduction in shedding of virus protein corresponded well with delayed onset of acute diarrhea (P < 0.02). Closer examination of tissue cross sections under electron microscopy revealed that the B. bifidum-ingested strain adhered to the epithelium of the small intestine. These results suggest that priming the intestine with B. bifidum is effective against experimental MRV challenge and confirmed the potential usefulness of this detector ELISA for studying the kinetics of group A rotavirus infection in animals and humans.

Animals↗
PubMed1994

Immune responses in humans and animals to meningococcal transferrin-binding proteins: implications for vaccine design.

The results reported here show that the two meningococcal transferrin-binding proteins (TBP1 and TBP2) generate different immune responses in different host species and that there is variation in response dependent on the method of antigen preparation and possibly the route of administration. Mice immunized with either whole cells of Neisseria meningitidis SD (B:15:P1.16) or the isolated TBP1-TBP2 complex from the same strain produced antisera which, when tested against a representative panel of meningococcal isolates by Western blotting (immunoblotting), recognized some but not all heterologous TBP2 molecules. In contrast, rabbit antisera raised to the same preparations were cross-reactive with almost all the TBP2 molecules. The immune response to TBP1 was also host species dependent. Western blot analysis with denatured TBP1 failed to detect antibodies in antisera raised in mice to whole cells or in a rabbit to the TBP1-TBP2 complex but detected broadly cross-reactive antibodies in mouse anti-TBP1-TBP2 complex sera and strain-specific antibodies in rabbit anti-whole-cell serum. Human convalescent-phase sera obtained from five patients infected with meningococci of different serogroups and serotypes contained fully cross-reactive antibodies to TBP2 but no anti-TBP1 antibodies, when examined on Western blots. However, on dot immunoblots, the same patients' sera, as well as the mouse anti-whole cell and the rabbit anti-TBP1-TBP2 complex sera, reacted with purified biologically active TBP1 of strain SD. This indicates that native TBP1, a protein which loses its biological and some of its immunological activities when denatured, is immunogenic and that humans generate cross-reactive antibodies to native epitopes. These observations have important implications for assessing the vaccine potential of TBPs and other meningococcal antigens. Conclusions regarding the usefulness of TBPs as candidate components of meningococcal serogroup B vaccines based on results from certain animal species such as mice, or on methods such as Western blotting, may have little bearing on the situation in humans and may lead to some potentially useful antigens being disregarded.

Animals↗
PubMed1994

Effectiveness of Bifidobacterium bifidum in mediating the clinical course of murine rotavirus diarrhea.

Human Bifidobacterium sp strain bifidum (B. bifidum) was administered to BALB/c lactating mice (n = 58) and their litters (n = 327 pups) to evaluate the ingested strain's adherent properties and ability to inhibit murine rotavirus (MRV) infection. ELISA and anaerobic bacteriologic techniques were used to measure MRV shedding and colonization of Bifidobacterium in the small intestine. At 13-16 d gestation, pregnant dams (and their expected litters) were randomly assigned to one of four experimental groups: 1) normal controls; 2) B. bifidum-treated only; 3) MRV-infected only; and 4) B. bifidum-treated + MRV-infected dams and litters. During the acute phase of diarrhea, 80% of small-intestine cultures in B. bifidum-treated litters were positive for the ingested B. bifidum strain compared with 24% of fecal cultures. Examination of tissue cross sections under electron microscopy revealed the ingested B. bifidum strain survived passage through the upper gastrointestinal tract and adhered to the small-intestine epithelium. After the administration of the high dose of virus, diarrhea developed in all pups, but onset was significantly delayed in B. bifidum-treated + MRV-infected litters compared with litters infected with MRV only (p < 0.02). B. bifidum-treated+MRV-infected pups demonstrated a significant reduction in MRV shedding compared with litters challenged with MRV only at d 2 to 10 after inoculation (p < 0.009). More direct studies are needed to assess mechanisms by which this anaerobe can alter the course of MRV infection at the level of gut epithelium.

Administration, Oral↗
PubMed1994

Ensuring the consistency of rDNA-derived biologicals: the contribution of gene sequencing.

The past few years have seen an interesting debate on the extent to which DNA-sequencing of expression systems is appropriate as a basis for assessing the quality and consistency of rDNA-derived products. While there is a need to improve and validate the ability of end-product testing procedures to detect low levels of variant proteins, there are several reasons why it may not be justified to require extensive DNA sequence analysis of large numbers of individual clones of producer cells. These include difficulties in interpreting the resultant data due to artefacts introduced by PCR and the fact that other events, such as translational errors and chemical and enzymic alterations during production and downstream processing, also lead to potential heterogeneity of pharmaceutical proteins. The evaluation of these products can only be made at the protein level. Some DNA sequencing will be required during product development, but in practice the quality and consistency of rDNA-derived products are best determined by a range of in-process and end-product testing procedures, including the use of biological assays and standardization.

Biological Products↗
PubMed1993

Antigenic relationships of transferrin-binding proteins from Neisseria meningitidis, N. gonorrhoeae and Haemophilus influenzae: cross-reactivity of antibodies to NH2-terminal peptides.

The NH2-terminal amino sequence through the first 20 amino acids was obtained for transferrin-binding protein (TBP)1 from three strains of Neisseria meningitidis. These were identical except for a glutamine to a glycine substitution at residue 6 in one case. The sequences of the NH2-terminal 20 amino acids of TBP2 from the same three strains were also determined; one TBP2 had a M(r) of 68,000 and the other two of 78,000. Sequences were identical up to residue 13 in all three proteins. Peptides based on the NH2-terminal sequences of TBP1 and 2 were synthesized, linked to Keyhole Limpet haemocyanin and used to raise antibodies in rabbits. Anti-peptide antibodies cross-reacted on immunoblotting with the respective TBPs from all meningococcal strains tested, as well as with those from N. gonorrhoeae, suggesting that the NH2-terminals of these proteins are well conserved in the Neisseria. Neither anti-peptide serum reacted with the analogous TBP1 and 2 from Haemophilus influenzae, although common epitopes have previously been shown to exist.

Amino Acid Sequence↗
PubMed1993

Alteration of transfer ribonucleic acid of Neisseria meningitidis during growth in the presence of human transferrin.

Iron-related tRNA alterations have been shown to occur in several pathogens but nothing has been reported about the effect of iron on meningococcal tRNA. The chromatographic elution profile of 3H-tryptophan-tRNA(trp) from a Neisseria meningitidis strain grown under different conditions was examined. The profile showed an early (P1) and a late (P2) eluting species of tRNA(trp), but the proportion of the two species varied under different growth conditions. The elution profile of trp-tRNA(trp) from bacteria grown in iron-sufficient Mueller Hinton broth yielded a minor P1 species and a major P2 species, whereas under iron-restricted growth induced by desferrioxamine, the pattern was one of a major P1 species and minor P2 species. Iron-restriction induced by human transferrin (HTF) resulted in almost equal amounts of the two tRNA(trp) species (P1 congruent to P2). Differences in the proportions of the tRNA species were also found between cells grown in liquid medium (P1 << P2) and on the same medium solidified with agar (P1 >> P2). The growth phase of the bacteria did not have any effect on the tRNA(trp) elution profile. Changes in tRNA(trp) induced by HTF were readily and completely reversible when the cells were transferred to an iron-rich medium, but those induced by desferrioxamine remained irreversible for a long period (16 h) after such transfer.

Culture Media↗
PubMed1993

Effectiveness of Bifidobacterium bifidum in experimentally induced MRV infection: dietary implications in formulas for newborns.

The protective effect of a human strain of Bifidobacterium bifidum (B. bifidum) against murine Group A rotavirus (MRV) was examined in the intestines of BALB/c infected mice. In experiments designed to determine whether B. bifidum mediated MRV shedding during diarrheal disease, pregnant dams (and their expected litters) were randomly assigned to the following groups: 1. Mice infected with MRV alone; 2. B. bifidum treated + MRV infected mice; 3. B. bifidum treated controls; 4. Saline control animals. An enzyme-linked immunosorbent assay (ELISA) for the detection of group A rotavirus was used to measure virus protein. Treatment with B. bifidum significantly reduced shedding of MRV antigen (P < 0.009) days 2-10 post-inoculation. The reduction in shedding of virus protein corresponded well with delayed onset of acute diarrhea (P < 0.02). Closer examination of tissue cross-sections under electron microscopy revealed that the B. bifidum ingested strain adhered to the epithelium of the small intestine. In further experiments, adherent properties of the ingested strain were related to enhancement, although nonsignificant, in immunoglobulin secreting cell responses in Peyer's patch lymphocytes. These results suggest that priming the intestine with B. bifidum is effective against experimental MRV challenge. Closer examination of B. bifidum and related growth factors in suckling neonates on gut physiology and enhancement of local immune responses has potential dietary implications in formulas for newborns.

Animals↗
PubMed1992

Common antigenic domains in transferrin-binding protein 2 of Neisseria meningitidis, Neisseria gonorrhoeae, and Haemophilus influenzae type b.

There is now considerable evidence to show that in the Neisseria and Haemophilus species, membrane receptors specific for either transferrin or lactoferrin are involved in the acquisition of iron from these glycoproteins. In Neisseria meningitidis, the transferrin receptor appears to consist of two proteins, one of which (TBP 1) has an M(r) of 95,000 and the other of which (TBP 2) has an M(r) ranging from 68,000 to 85,000, depending on the strain; TBP 2 binds transferrin after sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electroblotting, but TBP 1 does not do so. The relative contributions of these two proteins to the binding reaction observed with intact cells and to iron uptake are presently unknown. However, they are being considered as potential components of a group B meningococcal vaccine. Analogous higher- and lower-molecular-weight proteins associated with transferrin binding have been found in N. gonorrhoeae and Haemophilus influenzae. Previous work with polyclonal antibodies raised in mice with whole cells of iron-restricted N. meningitidis showed that the meningococcal TBP 2 exhibits considerable antigenic heterogeneity. Here, we report that antiserum against purified TBP 2 from one strain of N. meningitidis cross-reacts on immunoblotting with the TBP 2 of all meningococcal isolates examined, as well as with the TBP 2 of N. gonorrhoeae. This antiserum also cross-reacted with the TBP 2 of several strains of H. influenzae type b, thus showing the presence of common antigenic domains among these functionally equivalent proteins in different pathogens; no cross-reaction was detected with a purified sample of the human transferrin receptor.

Animals↗
PubMed1991

Iron and bacterial virulence--a brief overview.

Iron is now recognized as playing a vital role in infection. Not only does it restricted availability in tissue fluids present microbial pathogens with the problem of acquiring sufficient for multiplication in vivo, but it also constitutes a major environmental signal which co-ordinately regulates the expression of a number of virulence and metabolic genes. Progress in understanding the strategies used by pathogens for acquiring iron in vivo, and their responses to iron restriction, is providing a fresh insight into microbial pathogenicity.

Bacteria↗