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Biomedical subjects

M E Holt

Publications and source records attributed to M E Holt.

14 recordsLinked to original sources
PubMed1990

Protective effect of sera raised against different fractions of Streptococcus suis type 2.

Five bands of 44, 54, 78, 86 and 94 kD were identified by Western blot analysis of Streptococcus suis type 2 by the use of sera that were from immune or non-immune pigs and were positive or negative in bactericidal tests in vitro. These bands were cut from the gels and used as antigens to produce antisera in rabbits. Rabbit sera against the 78 and 94 kD bands were positive in bactericidal tests, and the serum against the 94 kD band also protected mice against challenge with a live pathogenic strain of S. suis type 2. The serum raised against the 78 kD band was not protective in mice and appeared to inhibit the protective effect of the 94 kD band antiserum. Rabbit sera raised against the 44, 54 and 86 kD bands were negative in bactericidal tests and failed to protect mice against challenge.

Animals↗
PubMed1990

Immunisation of pigs with killed cultures of Streptococcus suis type 2.

Ten intravenous inoculations of 10(10) formalin-killed pathogenic Streptococcus suis type 2 stimulated detectable levels of opsonic antibody and a strong protective response against intravenous challenge with 10(9) viable S suis type 2 of the same strain. Heat-killed organisms did not stimulate a protective response, even though the type-specific antigen was intact and opsonic antibodies were induced. When the number of formalin-killed organisms in the inoculum was increased 10-fold, one inoculation was insufficient to stimulate a protective response, but two inoculations protected pigs against intravenous challenge with live, pathogenic organisms. Four-hour and overnight cultures were equally immunogenic, and the response was not enhanced by either Freund's incomplete adjuvant or aluminium hydroxide gel adjuvant.

Animals↗
PubMed1989

Studies of the protective effect of different fractions of sera from pigs immune to Streptococcus suis type 2 infection.

Inoculation of mice with high doses of Streptococcus suis type 2 caused depression, anorexia, lethargy and sometimes death. This was prevented by prior inoculation of whole immune pig serum, the IgM and IgG fractions of immune pig serum and serum enriched with antibody to surface antigens. Clinical signs were not prevented by prior inoculation of pre-immune serum or serum depleted of antibody to surface antigens. Serum fractions that were protective in vivo were also opsonic in vitro. Western blot analysis identified two antigens of 44 and 78 kd that were recognized strongly by protective sera and a further four of 86, 94, 130 and 136 kd that were recognized less intensely.

Animals↗
PubMed1988

Immunisation of pigs with live cultures of Streptococcus suis type 2.

Repeated intravenous injections of pigs with live virulent cultures of Streptococcus suis type 2 stimulated a strong protective response against subsequent challenge. This protection was transferred passively to susceptible pigs by the inoculation of sera from protected pigs. A strong protective response was also stimulated by repeated inoculations of live cultures of non-pathogenic isolates. The protective response did not eliminate S suis type 2 organisms already established in the tonsils or joints, nor prevent the establishment of subclinical infection in the tonsils.

Animals↗
PubMed1987

Luminol dependent chemiluminescence and thiol group oxidation provoked by neutrophils is attributable to different oxidizing species.

Luminol-dependent chemiluminescence and thiol group oxidation of glutathione and human serum albumin were measured in order to demonstrate whether the inhibition of polymorphonuclear leukocyte chemiluminescence by albumin was attributable to thiol group oxidation. We have shown that: 1. thiol groups on glutathione and albumin are oxidized by PMNL stimulated by soluble and phagocytic stimuli; 2. thiol group oxidation in albumin and glutathione did not correlate with the inhibitory effects of these substances on luminol-dependent chemiluminescence with respect to time course, magnitude, effects of known scavengers or extracellular activity. It was therefore concluded that thiol group oxidation was not the cause of albumin inhibition of luminol-dependent chemiluminescence; 3. a metastable oxidant was identified after PMNL activation which was capable of oxidizing thiol groups but unable to elicit chemiluminescence from luminol.

Azides↗
PubMed1984

Deposition of eosinophil cationic protein in granulomas in allergic granulomatosis and vasculitis: the Churg-Strauss syndrome.

Biopsy specimens and tissues obtained at necropsy from two women who died after developing the Churg-Strauss syndrome were analysed to see whether granulomas in these patients contained activated eosinophils or secreted eosinophil cationic proteins, or both. Immunocytochemical studies with monoclonal antibody EG2 showed large amounts of eosinophil cationic protein and eosinophil protein-X (which are toxic for heart cells and other tissues) in the granulomas. Many activated and degranulating eosinophils were seen to be migrating from the blood into these areas. Eosinophils may play a central part in the development of lesions in the heart and other tissues in the Churg-Strauss syndrome.

Adolescent↗
PubMed1984

Methimazole and generation of oxygen radicals by monocytes: potential role in immunosuppression.

A study was conducted investigating the possibility that the immunosuppressive action of methimazole (the active metabolite of the antithyroid drug carbimazole) might be due to an effect on the production of oxygen radicals by monocytes. Techniques comprised measurement of luminol dependent chemoluminescence in monocytes and a spectrophotometric assay for production of hydrogen peroxide. The results showed definite inhibition of formation of oxygen radicals by resting and stimulated monocytes, which may explain the immunosuppressive action of the drug in Graves' disease. The findings also suggest that the formation of oxygen radicals and the initiation of the immune response may be closely related.

Cells, Cultured↗
PubMed1984

Albumin inhibits human polymorphonuclear leucocyte luminol-dependent chemiluminescence: evidence for oxygen radical scavenging.

Luminol-dependent chemiluminescence of normal human polymorphonuclear leucocytes (PMN) which were resting, or stimulated by unopsonized latex beads, opsonized zymosan or the chemotactic peptide N-formyl-met-leu-phe was decreased more than 80% in the presence of physiological concentrations of albumin (4%, w/v). This inhibition did not result from impairment of light transmission, cellular toxicity, luminol excited-state quenching or a dialysable contaminant in the albumin preparation, but was reduced by 30% when the fall induced by albumin in extracellular free Ca2+ concentration was corrected. The inhibition was most apparent in the larger second phase of the PMN chemiluminescent response to chemotactic peptide or opsonized zymosan stimulation. The smaller first phase of these responses was in fact enhanced by low concentrations of albumin (0.05-0.5%, w/v) and only inhibited up to 50% by 4% (w/v) albumin. Albumin in the range 0.1-4% (w/v) exerted a similar effect on chemiluminescence resulting from superoxide anion (O-2) and hydrogen peroxide (H2O2) production by xanthine oxidase catalysed oxidation of xanthine in the presence of luminol. We suggest that the effect of albumin on PMN luminol-dependent chemiluminescence is mediated by modification of the oxygen radical generating pathway, or oxygen radical scavenging. This previously undocumented property of the major extracellular protein requires further examination if oxygen radicals are to be established as important mediators of inflammation.

Cell Survival↗