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M Van Kleef

Publications and source records attributed to M Van Kleef.

9 recordsLinked to original sources
PubMed2002

Low molecular weight proteins of Cowdria ruminantium (Welgevonden isolate) induce bovine CD4+-enriched T-cells to proliferate and produce interferon-gamma.

An important objective in vaccination strategies is to activate lymphocytes with particular effector functions. Cellular immunity and the type I cytokine IFN-gamma have been implicated in protective immunity to heartwater. Furthermore, low molecular weight proteins of Cowdria ruminantium have been shown to induce peripheral blood mononuclear cells to proliferate. To determine which lymphocyte subset responds when stimulated with fractionated C. ruminantium proteins, specific short-term lymphocyte cultures were established from cattle immunized with the Welgevonden isolate. Four cattle were immunized, two by infection and treatment and two with inactivated organisms. Cell surface phenotypic analysis of the cultures indicated that CD4+ lymphocytes were enriched over time. This coincided with increased antigen-specific proliferation and IFN-gamma production. Proteins of molecular weights 13-18kDa induced the CD4+-enriched T-cell cultures, derived from each of the animals, to proliferate and produce IFN-gamma. Although the two groups of cattle were immunized differently, their lymphocytes responded similarly. These results extend previous findings by identifying the responder cells as being predominantly IFN-gamma producing CD4+ lymphocytes. This cytokine has been implicated in immunity to the parasite. The low molecular weight proteins that induced CD4+ lymphocytes to proliferate and produce IFN-gamma are therefore likely to be important in protection against heartwater and may have a role in vaccine development.

Animals↗
PubMed2002

Cowdria ruminantium antigens of around 15 kDa are potent inducers of IFN-gamma.

Cellular responses induced in two Creole goats by vaccination with killed Cowdria ruminantium (Cowdria) were confirmed by IFN-gamma production and interleukin-2 receptor (IL-2R) expression. Both CD4+ and CD8+ but not WC1+ T cells showed a substantial increase in cell surface expression of IL-2R molecules in response to whole Cowdria lysate. Cowdria (Welgevonden strain) proteins were fractionated using continuous-flow electrophoresis and tested for their ability to induce IFN-gamma production by PBMC collected three weeks after the first inoculation and one week after the booster injection. Pooled fractions of around 15, 22, and 24 kDa were found to induce significant IFN-gamma production in both vaccinated animals on one of the two occasions. Antigens of around 15 kDa induced substantially higher IFN-gamma production than any other fractions in both animals. These pilot experiments pave the way towards the identification of proteins/genes that have potential for the development of a recombinant vaccine against heartwater.

Animals↗
PubMed2000

Identification of Cowdria ruminantium antigens that stimulate proliferation of lymphocytes from cattle immunized by infection and treatment or with inactivated organisms.

Cowdria ruminantium is an obligate intracellular pathogen that causes heartwater in ruminants. Several findings suggest that T cells play an important role in protection against the disease. In order to identify which proteins are involved in T-cell immunity, C. ruminantium proteins were fractionated by continuous-flow electrophoresis and tested for their ability to stimulate lymphocyte proliferation in vitro. C. ruminantium-infected endothelial cell lysates were fractionated at between 11 and 38 kDa and 50 and 168 kDa on 15 and 7% acrylamide gels, respectively. In an attempt to stimulate the natural infective process, peripheral blood mononuclear cells (PBMC) were obtained from two cattle rendered immune by infection and treatment and assayed in proliferation assays with fractionated proteins. In a parallel study, four cattle were immunized with inactivated C. ruminantium to determine whether their lymphocytes also responded to fractionated proteins. Proliferation assays after immunization by infection and treatment detected no C. ruminantium-specific proliferation in vitro after one vaccination. Proliferation was observed, however, between 1 and 4 weeks after challenge. This was followed by a period of no detectable response, after which the response reappeared. PBMC from animals immunized with inactivated organisms proliferated specifically in response to antigen soon after the first immunization. Only C. ruminantium proteins with low molecular masses of 11, 12, 14 to 17, and 19 to 23 kDa induced proliferative responses by lymphocytes from all six animals. These protein fractions may have potential as vaccine antigens.

Animals↗
PubMed1999

Relapsing ulcerative colitis associated with spinal cord stimulation.

Spinal cord stimulation is an increasingly popular form of pain treatment. An electrode positioned on the dorsal aspect of the spinal cord at the level of the nerve roots from the painful area stimulates the spinal cord. Current from the electrode is supplied by a pulse generator in the lower anterior abdominal wall. Spinal cord stimulation has not previously been associated with ulcerative colitis. A man with left-sided ulcerative colitis in remission experienced two successive relapses related to the use of a spinal cord stimulation system. After removal of the system, remission returned and remained. This case suggests that electrical current may influence the course of ulcerative colitis.

Colitis, Ulcerative↗
PubMed1999

Electrical spinal cord stimulation in reflex sympathetic dystrophy: retrospective analysis of 23 patients.

OBJECT: The aim of the study was to assess retrospectively the clinical efficacy and possible adverse effects of electrical spinal cord stimulation (SCS) for the treatment of patients with reflex sympathetic dystrophy (RSD). METHODS: Twenty-three patients who suffered severe pain due to RSD were included in the study. The SCS system was implanted only after a positive 1-week test period. The visual analog scale (VAS) score for pain (1-10) was obtained in all patients prior to treatment, 1 month postimplantation, and at last follow up. At final follow-up examination, patients were asked to rate the effect of their treatment on the 7-point global perceived effect scale. Eighteen (78%) of 23 patients treated between 1991 and 1997 reported improvement during the test period. Permanent implantation of SCS system was not performed in the other five patients. Complications occurred in nine (50%) of 18 patients. The system was removed in three patients after implantation (17%). At the end of follow up (mean 32 months) 15 patients still had an implanted system. The mean pain score had decreased from 7.9 to 5.4 (p<0.001). In the other eight patients the pain score had not changed significantly. In 13 patients (57%) in whom the SCS system was implanted, clinical status had much improved or improved; these cases were regarded as successful. CONCLUSIONS: In this retrospective series, the majority of patients with RSD reported a subjective improvement after implantation of an SCS system.

Adult↗
PubMed1998

Neurogenic inflammation and reflex sympathetic dystrophy (in vivo and in vitro assessment in an experimental model).

In the chronic constriction injury (CCI) model, signs and symptoms similar to those observed in reflex sympathetic dystrophy (RSD) can be induced by loosely ligating a rat sciatic nerve. Skin microcirculatory (inflammation-like) disorders may result from release of vasoactive neuropeptides at peripheral endings of antidromically acting nociceptive nerve fibers. These antidromic mechanisms may account for vasodilation and polymorphonuclear leukocyte (PMN) accumulation in the ligated hindpaw. We assessed skin blood flow (SBF) on the ligated side, by means of laser Doppler flowmetry, before as well as at day 4 after ligation. Postligation SBF measurements were performed before and after selective (capsaicin) conduction blockade of the ligated sciatic nerve. The extent of PMN accumulation was determined by measuring myeloperoxidase (MPO) activity in muscle biopsies obtained from the ligated and contralateral nonligated side. As compared to preligation SBF values, we observed an increase at day 4. SBF returned to preligation values consequent to capsaicin application. MPO activity, when compared to the nonligated side, was higher in biopsies obtained from the ligated side. These findings indicate that in the CCI-model, antidromically acting C-nociceptor nerve fibres increase SBF at 4 days after ligation. In addition, these antidromic mechanisms may induce an inflammatory response in the ipsilateral hindpaw, mediated by release of neuropeptides from the peripheral endings of antidromically acting C-nociceptor nerve fibers. This inflammatory response may account for various signs and symptoms as observed in the CCI model and may mirror pathophysiological mechanisms of RSD.

Animals↗
PubMed1993

Isolation and characterization of antigenic proteins of Cowdria ruminantium.

Two antigenically conserved Cowdria ruminantium proteins, an immunodominant 31 kDa and a minor 27 kDa protein, were characterized. The 31 kDa and 27 kDa proteins are single polypeptide chains. The 31 kDa protein contains no glycoconjugates and the partial, internal amino acid sequence was determined. The acidic nature of this protein, deduced from the amino acid composition, was confirmed by IEF (pI 5.7). Monospecific antiserum was prepared against the 27 and 31 kDa proteins and results indicate that they are immunogenic and share common epitopes.

Amino Acid Sequence↗