PubMed Health⌕ Search

Biomedical subjects

P J Jenner

Publications and source records attributed to P J Jenner.

At least 19 recordsLinked to original sources
PubMed2001

Changes in gene expression in macrophages infected with Mycobacterium tuberculosis: a combined transcriptomic and proteomic approach.

We investigated the changes which occur in gene expression in the human macrophage cell line, THP1, at 1, 6 and 12 hr following infection with Mycobacterium tuberculosis. The analysis was carried out at the transcriptome level, using microarrays consisting of 375 human genes generally thought to be involved in immunoregulation, and at the proteomic level, using two-dimensional gel electrophoresis and mass spectrometry. The analysis of the transcriptome using microarrays revealed that many genes were up-regulated at 6 and 12 hr. Most of these genes encoded proteins involved in cell migration and homing, including the chemokines interleukin (IL)-8, osteopontin, monocyte chemotactic protein-1 (MCP-1), macrophage inflammatory protein-1alpha (MIP-1alpha), regulated on activation, normal, T-cell expressed and secreted (RANTES), MIP-1beta, MIP-3alpha, myeloid progenitor inhibitory factor-1 (MPIF-1), pulmonary and activation regulated chemokine (PARC), growth regulated gene-beta (GRO-beta), GRO-gamma, MCP-2, I-309, and the T helper 2 (Th2) and eosinophil-attracting chemokine, eotaxin. Other genes involved in cell migration which were up-regulated included the matrix metalloproteinase MMP-9, vascular endothelial growth factor (VEGF) and its receptor Flk-1, the chemokine receptor CCR3, and the cell adhesion molecules vesicular cell adhesion molecule-1 (VCAM-1) and integrin a3. In addition to the chemokine response, genes encoding the proinflammatory cytokines IL-1beta (showing a 433-fold induction), IL-2 and tumour necrosis factor-alpha (TNF-alpha), were also found to be induced at 6 and/or 12 hr. It was more difficult to detect changes using the proteomic approach. Nevertheless, IL-1beta was again shown to be strongly up-regulated. The enzyme manganese superoxide dismutase was also found to be strongly up-regulated; this enzyme was found to be macrophage-, rather than M. tuberculosis, derived. The heat-shock protein hsp27 was found to be down-regulated following infection. We also identified a mycobacterial protein, the product of the atpD gene (thought to be involved in the regulation of cytoplasmic pH) in the infected macrophage extracts.

Chemokines↗
PubMed2001

Slow induction of RecA by DNA damage in Mycobacterium tuberculosis.

In mycobacteria, as in most bacterial species, the expression of RecA is induced by DNA damage. However, the authors show here that the kinetics of recA induction in Mycobacterium smegmatis and in Mycobacterium tuberculosis are quite different: whilst maximum expression in M. smegmatis occurred 3-6 h after addition of a DNA-damaging agent, incubation for 18-36 h was required to reach peak levels in M. tuberculosis. This is despite the fact that the M. tuberculosis promoter can be activated more rapidly when transferred to M. smegmatis. In addition, it is demonstrated that in both species the DNA is sufficiently damaged to give maximum induction within the first hour of incubation with mitomycin C. The difference in the induction kinetics of recA between the two species was mirrored by a difference in the levels of DNA-binding-competent LexA following DNA damage. A decrease in the ability of LexA to bind to the SOS box was readily detected by 2 h in M. smegmatis, whilst a decrease was not apparent until 18-24 h in M. tuberculosis and then only a very small decrease was observed.

Alkylating Agents↗
PubMed1998

An immunodominant epitope from mycobacterial 65-kDa heat shock protein protects against pristane-induced arthritis.

Previous studies showed that mice with pristane-induced arthritis (PIA) and those protected from the disease by preimmunization with mycobacterial 65-kDa heat shock protein (hsp65) possess raised immune responses to hsp65. Additionally, T cells from hsp65-protected mice, but not from pristane-injected or normal mice, produced the Th2-associated cytokines IL-4, IL-5, and IL-10 in response to stimulation with hsp65. Here we demonstrate that the specificity of the immune response to hsp65 and related heat shock protein (hsps) differs between protected and PIA mice. T cells from hsp65-protected mice respond to the bacterial hsps tested but not to the mammalian homologue, hsp58. Similarly, they exhibit high serum titers of anti-hsp65 Abs, yet they have virtually undetectable levels of anti-hsp58 IgG. By contrast, both cellular and humoral immune responses are detectable to bacterial and mammalian hsps in mice with PIA. An immunodominant T cell epitope has been identified in hsp65-protected mice corresponding to amino acids 261-271 from hsp65. Immunization of mice, either before or after the induction of arthritis, with this bacterial peptide, but not its mammalian homologue, protects mice from the development of PIA, and protection is associated with the production of Th2-type cytokines. Other experiments revealed that T cells primed with bacterial 261-271 or the mammalian homologue do not cross-react at the proliferative or cytokine level. These results demonstrate that an hsp65 peptide-specific Th2 response confers protection from PIA but do not support the idea that protection is mediated by a cross-reaction with self hsp58 in the joints.

Animals↗
PubMed1995

Protein splicing--the lengths some proteins will go to.

We review the recently discovered phenomenon of protein splicing which is the excision of an internal protein sequence at the protein level rather than at the RNA level. The means by which examples of protein splicing have been identified are described, and the similarities of the internally spliced protein products (or inteins) are discussed. Comparisons are made between inteins and group I RNA introns. We describe the evidence supporting excision of intiens by a post-translational autocatalytic reaction of a full length polypeptide precursor, rather than by RNA splicing. An examination is made of some of the proposed mechanism schemes and the supporting them presented.

Amino Acid Sequence↗
PubMed1994

Sera of leprosy patients with type 2 reactions recognize selective sequences in Mycobacterium leprae recombinant LSR protein.

Type 2 reactions (erythema nodosum leprosum [ENL]) are episodic, reactional states causing significant morbidity in lepromatous leprosy patients. With a view to defining the immunological differences between the stable and reactional forms of lepromatous leprosy, we determined antibody responses to LSR, a recombinant protein of Mycobacterium leprae previously described by us (S. Laal, Y.D. Sharma, H.K. Prasad, A. Murtaza, S. Singh, S. Tangri, R. S. Mishra, and I. Nath, Proc. Natl. Acad. Sci. USA 88:1054-1058, 1991), as well as to 10- to 15-mer overlapping peptides synthesized on the basis of the LSR amino acid sequence. We report here the selective recognition of B cell epitopes by sera from patients with ENL as compared with a control group with nonreactional lepromatous leprosy. Peptides 2 and 3, with the sequences GVTYEIDLTNKNAA and IDLTNKNAAKLRGD, respectively, were recognized by > 95% of sera from patients with active ENL. Peptide 3 in addition showed reactivity with sera taken from 91.6% of lepromatous leprosy patients who were apparently stable but who were recorded to have had ENL several weeks before or after the sample collection. The core sequence IDLTNKNAA common to both these peptides may be a major target of humoral responses in ENL. In addition, the RGD motif at the C terminus appeared to influence the antigenicity of peptide 3 in enzyme-linked immunosorbent assay. It would appear that humoral responses during ENL are directed to selective antigenic determinants of the leprosy bacillus. The use of such serological markers to identify lepromatous leprosy patients with a high risk for developing ENL would be of clinical and predictive value.

Antibodies, Bacterial↗
PubMed1994

Critical residues of the Mycobacterium leprae LSR recombinant protein discriminate clinical activity in erythema nodosum leprosum reactions.

We reported earlier (S. Singh, N. P. Shanker Narayan, P. J. Jenner, G. Ramu, M. J. Colston, H. K. Prasad, and I. Nath, Infect. Immun. 62:86-90, 1994) that polyclonal antibodies directed against selective sequences in the Mycobacterium leprae recombinant protein designated LSR were present in lepromatous leprosy patients undergoing erythema nodosum leprosum (ENL) reactions (type 2 reactions). In this study using peptides with single-residue deletions from positions 6 to 24, we define three distinct regions, GVTY, NAA, and RGD, which were important for antibody recognition and for the discrimination of clinically silent and active ENL reactions. Antibodies against NAA were found only in patients undergoing active reactions. This is in contrast to the results for the RGD motif, which was recognized in all ENL patients, irrespective of the clinical status. Though GVTY was recognized in both groups of patients, its recognition was masked by the flanking glutamic acid. These findings point towards a specific molecular recognition pattern that emerges when a lepromatous leprosy patient undergoes immune perturbations leading to ENL reactions. Moreover, the fine specificity of immunological recognition changes during the natural evolution of the host-parasite interaction.

Amino Acid Sequence↗
PubMed1992

Protein splicing in the maturation of M. tuberculosis recA protein: a mechanism for tolerating a novel class of intervening sequence.

The M. tuberculosis recA locus comprises an 85 kd open reading frame but produced 38 kd RecA and 47 kd products in E. coli. No RNA processing was detected; rather, an 85 kd precursor protein was spliced, releasing a 47 kd spacer protein, and joining its terminal fragments to form mature RecA protein. "Spacer" protein was also produced in M. tuberculosis and from a hybrid spacer-LacZ alpha fusion molecule. Mutagenesis at codon wobble positions at one splice junction showed that protein rather than nucleotide sequence determined splicing activity. Other mutants defined additional regions needed for splicing and allowed processing to be followed. Splicing was essential for RecA activity in E. coli. The possibility that splicing is a manifestation of a novel class of genetic element is discussed.

Amino Acid Sequence↗
PubMed1992

Mitochondrial function in Parkinson's disease. The Royal Kings and Queens Parkinson's Disease Research Group.

There is increasing evidence for a defect of mitochondrial respiratory chain function in Parkinson's disease. Specific NADH CoQ1 reductase (complex I) deficiency has been identified in the substantia nigra. Available evidence suggests that this defect is confined to the substantia nigra and is not present elsewhere in the parkinsonian brain. The absence of a detectable mitochondrial abnormality in the substantia nigra of patients with multiple system atrophy also suggests that the complex I deficiency in Parkinson's disease is not simply due to an artifact of neuronal degeneration. Evidence for abnormal mitochondrial function in skeletal muscle is conflicting; two studies showed multiple respiratory chain defects and one study was unable to demonstrate any deficiency. A severe deficiency of complex I activity has been found in platelet mitochondria from parkinsonian patients. This finding has not as yet been confirmed. Platelet homogenates do not show the complex I deficiency, however, suggesting that such a preparation may be too insensitive to detect the defect. The role of complex I deficiency in the events that culminate in dopaminergic cell death in Parkinson's disease remains unresolved. It is likely that if this mitochondrial defect is confirmed, it will be related to a number of other factors, including environmental agents, oxidative stress, and genetic predisposition.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1991

The antibody repertoire to proteins of Mycobacterium leprae. Genetic influences at the antigen and epitope level.

The effects of both H-2 and non-H-2 genes on the antibody response to the proteins of Mycobacterium leprae were investigated. Using a B10 series of congenic mice we found that the repertoire of antibody responses was under H-2 gene control, and that non-H2 genes were also involved. By Western blotting, differences in the number and m.w. of proteins recognised by mice of different genetic background were apparent. Such differences were also reflected in the total antibody response to a soluble extract of M. leprae (M. leprae sonicate), as measured by ELISA. Concentrating on one particular Ag, the 65-kDa heat shock protein, we found that all strains of mice developed antibodies following immunization with the purified recombinant protein, although there was a continuous distribution in the titer of antibodies obtained, with differences between individual strains indicating both H-2 and non-H-2 effects. Using a library of overlapping peptides based on the amino acid sequence of this protein, we have mapped the B cell epitopes in the different strains of mice. H-2 genes had no effect on the structure and number of epitopes recognized, although this was influenced by non-H-2 genes. There was a high level of concordance between actual epitopes recognized and those predicted by calculations of antigenic index, and B cell epitopes were located in similar positions to previously determined T cell epitopes.

Amino Acid Sequence↗
PubMed1991

Epitope specificity and MHC restriction of rheumatoid arthritis synovial T cell clones which recognize a mycobacterial 65 kDa heat shock protein.

CD4+ T cell clones specific for the mycobacterial hsp 65 were obtained from synovial fluid of a DR4 homozygous rheumatoid arthritis (RA) patient. A stimulatory epitope was defined using both deletion mutants of the mycobacterial hsp 65 and synthetic peptides and proved to be in a highly conserved region of the molecule. Despite this, however, there was no recognition by these clones of either the recombinant human homologue of mycobacterial hsp 65, P60, nor of a synthetic peptide containing an amino acid sequence from P60 corresponding to the epitope defined in the mycobacterial hsp 65. When the pattern of HLA restriction shown by the hsp-65-specific T cell clones was investigated, all clones tested proved to be restricted by HLA-DP rather than the more usual HLA-DR. Inhibition experiments suggested that this restriction also applied to the polyclonal synovial T cell response to hsp 65, but not to other antigens. Exclusive restriction of T cell recognition of an antigen by HLA-DP has not been reported previously, and strongly suggests that in this case the T cell repertoire for recognizing hsp 65 in the context of DR4 is deficient. Such an association between DR4 and the inability to respond to an immunodominant bacterial antigen may have implications for the pathogenesis of RA.

Amino Acid Sequence↗
PubMed1990

Recognition of a mycobacteria-specific epitope in the 65-kD heat-shock protein by synovial fluid-derived T cell clones.

Adjuvant arthritis in rats is induced by a T cell clone specific for amino acids 180-188 of the mycobacterial 65-kD heat-shock protein, and synovial T cell responses to this same Ag have been noted in human arthritis. We have isolated 65-kD Ag-specific T cell clones from synovial fluid mononuclear cells of a patient with acute arthritis, which, unlike the corresponding PBMC, showed a marked proliferative response to the 65-kD Ag. Using synthetic peptides corresponding to the whole sequence of the 65-kD Ag, all the clones were shown to recognize an epitope present in the first NH2-terminal peptide (amino acids 1-15), with no response to the adjacent peptide (amino acids 6-22) or to any other peptide. The complete dominance of this epitope in the response to the 65-kD Ag was shown by documenting responses to the peptide in PBMC obtained after recovery from the arthritis. This epitope, like that recognized by the rat arthritogenic T cell clone, is in a portion of the 65-kD sequence that is not conserved between bacteria and eukaryotes, so that in this case, joint inflammation could not be attributed to bacteria-induced T cell clones cross-reacting with the self 65-kD Ag.

Antigens, Bacterial↗
PubMed1990

Identification, sequencing, and expression of Mycobacterium leprae superoxide dismutase, a major antigen.

The gene encoding a major 28-kilodalton antigen of Mycobacterium leprae has now been sequenced and identified as the enzyme superoxide dismutase (SOD) on the basis of the high degree of homology with known SOD sequences. The deduced amino acid sequence shows 67% homology with a human manganese-utilizing SOD and 55% homology with the Escherichia coli manganese-utilizing enzyme. The gene is not expressed from its own promoter in E. coli but is expressed from its own promoter in Mycobacterium smegmatis. The amino acid sequences of epitopes recognized by monoclonal antibodies against the 28-kilodalton antigen have been determined.

Amino Acid Sequence↗
PubMed1989

Isoniazid-related hepatotoxicity: a study of the effect of rifampicin administration on the metabolism of acetylisoniazid in man.

It has been proposed that isoniazid-induced hepatotoxicity may be increased by concomitant rifampicin treatment and that this could be mediated by inducing the metabolism of the isoniazid metabolite monoacetylhydrazine to potent acylating agents capable of causing liver necrosis. To investigate this postulated mechanism we studied the kinetics of the metabolism of acetylisoniazid in a slow and a rapid acetylator prior to and after rifampicin administration. Pretreatment with rifampicin did not modify the metabolism of acetylisoniazid to any noteworthy extent nor did it increase the metabolism by non-acetylation routes of the monoacetylhydrazine liberated in vivo from acetylisoniazid.

Acetylation↗
PubMed1986

The neurotoxic actions of 6-hydroxydopamine infused into the rat substantia nigra.

6-Hydroxydopamine (6-OHDA) 10 and 40 micrograms/24 h infused bilaterally for 4 days into the rat substantia nigra (SN) caused a 'freezing' akinetic response which was apparent within 24 h and which persisted throughout the period of infusion. The infusion of 10 or 40 micrograms/24 h 6-OHDA into the SN failed to cause any change in motor coordination, or induce limb and body rigidity. The infusion of 40 micrograms/24 h 6-OHDA led to significant reductions in the striatal levels of dopamine, 3,4-dihydroxyphenylacetic acid, homovanillic acid and noradrenaline; no changes were observed following the 4-day infusion of 10 micrograms 6-OHDA. The consequences of infusing 6-OHDA into the SN are discussed in relation to those induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4-phenylpyridine (MPP+) where the spectrum of behavioural and biochemical change caused by 6-OHDA is shown not to mimic the actions of either MPTP or MPP+.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1986

A simple, inexpensive urine test of smoking.

Three novel colorimetric methods of detecting urinary nicotine metabolites called the barbituric acid, diethylthiobarbituric acid (DETB) and DETB-extraction methods were evaluated for use as a simple cheap objective test of smoking. Urine samples were collected from 103 male smokers and 78 male nonsmokers working at two London factories. The smokers recorded the number of cigarettes smoked over the previous 36 hours. All three methods correctly classified the smokers. The DETB-extraction method had a lower false-positive rate (averaging 3% on morning and afternoon urine samples) than either the DETB or barbituric acid methods (12% and 6% respectively) and was the best procedure for classifying subjects as 'smokers' or 'non-smokers'. Using a quantitative variant of the barbituric acid method, there was a significant correlation (r = 0.85, p less than 0.001) between the urinary nicotine metabolites/creatinine ratios and number of cigarettes smoked. However, the ratios for smokers of 6-15, 16-25, and 26 or more cigarettes overlapped considerably. The methods can be performed very rapidly and reagent costs are equivalent to less than one penny per test.

Barbiturates↗
PubMed1985

A simple, inexpensive urine test of smoking.

Three novel colorimetric methods of detecting urinary nicotine metabolites called the barbituric acid, diethylthiobarbituric acid (DETB), and DETB extraction methods were evaluated for use as a simple, cheap, objective test of smoking. Urine samples were collected from 103 male smokers and 78 male non-smokers working at two London factories. The smokers recorded the number of cigarettes smoked over the previous 36 hours. All three methods correctly classified the smokers. The DETB extraction method had a lower false positive rate (averaging 3% on morning and afternoon urine samples) than either the DETB or the barbituric acid method (12% and 6% respectively) and was the best procedure for classifying subjects as "smokers" or "non-smokers." When a quantitative variant of the barbituric acid method was used there was a significant correlation (r = 0.85, p less than 0.001) between the ratios of urinary nicotine metabolites to creatinine and the number of cigarettes smoked. The ratios for smokers of 6-15, 16-25, and 26 or more cigarettes, however, overlapped considerably. The methods can be performed very rapidly and the reagent cost is equivalent to less than 1p per test.

Barbiturates↗