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At least 1,225 records · Page 68Linked to original sources
PubMed2003

IgD-receptor (IgD-R) cross-linking partially protects murine T cells from dexamethasone-induced apoptosis.

Based on our previous findings that immunoglobulin D (IgD) receptor (IgD-R) cross-linking with oligomeric IgD (IgD-R-xL) led to T cell activation, we examined the effect of IgD-R-xL on the expression of Fas antigen and apoptosis induction. In splenic T cells, IgD-R-xL followed by dexamethasone (dex) treatment resulted in a decreased percentage of Fas-positive cells as well as a decreased mean fluorescence intensity (P<0.05) when compared with cells treated with dex alone. There are significant differences in annexin-fluorescein isothiocyanate (FITC) and phosphatidylinositol (PI) staining between samples treated with dex alone and IgD-R-xL followed by dex-treated samples (P<0.05), suggesting a protective role for IgD-R-xL. No significant differences are seen in Fas antigen expression, annexin-FITC staining, and/or PI staining in murine T hybridoma (7C5) cells cultured under similar conditions (P<0.07). We hypothesize that ligation of IgD-R may predispose antigen-specific T lymphocytes for survival during primary immune responses when IgD-positive B cells serve as antigen-presenting cells.

Animals↗
PubMed2005

Hyaluronan cross-linking: a protective mechanism in inflammation?

Production of the glycosaminoglycan hyaluronan is increased at sites of inflammation, often correlating with the accumulation of leukocytes. Mounting evidence suggests that this polysaccharide can be organized into a wide variety of molecular architectures by its association with specific binding proteins, leading to the formation of fibrils and cable-like structures involving a large number of hyaluronan chains. We propose that hyaluronan cross-linking is part of a protective mechanism, promoting adhesion of leukocytes to the hyaluronan complexes rather than enabling contact with inflammation-promoting receptors on the underlying tissues. Leukocytes are thus maintained in a non-activated state by appropriate receptor clustering or receptor co-engagement. Additionally, hyaluronan networks might serve as scaffolds to prevent the loss of extracellular matrix components during inflammation and to sequester proinflammatory mediators.

Animals↗
PubMed1996

Mapping of protective and cross-reactive domains of the type A neurotoxin of Clostridium botulinum.

The purpose of this study was to identify the location of domains within the serotype A neurotoxin of Clostridium botulinum (BoNT/A) that conferred protection against botulism. The BoNT/A gene was subcloned into a series of 10 overlapping fragments that were expressed in Escherichia coli. The expressed proteins were partially purified and used to immunize mice. The resulting antisera were screened by immunoblotting analysis for the presence of BoNT/A-specific antibody. All fragments, except one, elicited antibody that recognized BoNT/A in an immunoblot. Serological screening identified several fragment-specific cross-reactive epitopes that were shared by heterologous serotypes of BoNT. Most of these epitopes immunoreactive by enzyme-linked immunosorbent assay, but not by immunoblot. Only two fragments were shown to confer protection against BoNT/A intoxication. Both of these proteins were derived from segments of the heavy chain and encoded amino acid residues H455-661 and H1150-1289 of BoNT/A.

Animals↗
PubMed1999

Cross-bred cattle protected against Hyalomma anatolicum anatolicum by larval antigens purified by immunoaffinity chromatography.

Antigens from larvae of Hyalomma anatolicum anatolicum were extracted and purified by immunoaffinity chromatography using immunoglobulin ligands from cross-bred animals immunized with soluble larval antigen. Affinity-purified antigen (Aff-TLE) and a total larval extract (TLE) were used to immunize cross-bred (Bos indicus x Bos taurus) cattle. The group immunized with Aff-TLE rejected 71.6% of larvae and 77.3% of nymphs. However, the rejection percentages were lower in the TLE-immunized group. No significant changes in the feeding period, moulting percentages or moulting period of engorged larvae and nymphs were recorded. There was, however, a significant decrease in the number of resultant nymphs p < 0.01) and adults (p < 0.01) in the ticks fed on the Aff-TLE-immunized group. The Aff-TLE antigen was 93.3% purified. SDS-PAGE analysis identified a 39 kDa protein, reported for the first time, as the antigen responsible for the induction of resistance in the host.

Animals↗
PubMed1999

Cosegregation analysis in genetic crosses suggests a protective role for atrial natriuretic factor against ventricular hypertrophy.

In most rat models studied to date, increased ventricular mass is associated with high ventricular expression of the atrial natriuretic factor (ANF) gene. However, it is unknown whether ANF plays a beneficial or detrimental role in the course of left ventricular hypertrophy or whether ANF gene expression could be genetically linked to cardiac mass. To address such questions, we performed a cosegregation analysis in genetic crosses of inbred strains of rats. To select strains with the appropriate phenotypic characteristics, we first compared the ventricular abundance of ANF mRNA to ventricular mass (corrected for body weight) in 2 recombinant inbred strains derived from Wistar-Kyoto (WKY)/spontaneously hypertensive rat (SHR) hybrid crosses, ie, WKY-derived hyperactive (WKHA) and WKY-derived hypertensive (WKHT) rats, as well as in their parental inbred strains. In the 2 such strains that were normotensive, we observed that ventricular mass was higher in WKHA than in WKY rats, yet ventricular ANF mRNA was less abundant in WKHA than in WKY rats. Within a segregating population of F2 animals generated from a cross between WKY and WKHA genitors, the abundance of ventricular ANF mRNA and peptide correlated inversely with left ventricular mass, in contrast to the positive correlation observed with beta-myosin heavy chain mRNA. Finally, in the equally hypertensive SHR and WKHT strains, we found that ventricular mass was higher in SHR than in WKHT, yet ventricular ANF mRNA was less abundant in SHR than in WKHT. These results demonstrate for the first time that low ventricular ANF gene expression can be linked genetically to high cardiac mass independently of blood pressure and are consistent with a protective role for ANF against left ventricular hypertrophy.

Actins↗
PubMed2004

Experimental studies on myocardial protection with intermittent cross-clamp fibrillation: additive effect of the sodium-hydrogen exchanger inhibitor, cariporide.

BACKGROUND: We previously showed that intermittent cross clamping with fibrillation affords myocardial protection equivalent to cardioplegic arrest. In this study, we examined whether cariporide (Aventis Pharma, Frankfurt, Germany), a specific sodium-hydrogen exchanger inhibitor, enhanced the protective effect of intermittent cross-clamp fibrillation (ICCF). METHODS: Isolated rat hearts were Langendorff-perfused (20 mins) with bicarbonate buffer and function (left ventricular developed pressure) measured. In each of three separate protocols that incorporated progressively longer ischemic durations, hearts were randomly allocated to one of three groups: group 1 was the control group with 40, 60, or 80 minutes of continuous global ischemia. Group 2 was the ICCF group with 4, 6, or 8 cycles of 10 minutes ICCF and 10 minutes of reperfusion in sinus rhythm. Group 3 was the ICCF plus cariporide group, which was the same as group 2, but also with 3 micromoles/L cariporide present in perfusate from 10 minutes before the ICCF cycles. Hearts were reperfused for 60 minutes with drug-free buffer and recovery (percentage of initial function) was measured. Hearts were maintained at 37 degrees C throughout the protocols. In protocol 3 (80 minutes ischemia per 8 cycles of ICCF), creatine kinase leakage (myocardial injury) and triphenyl tetrazolium chloride staining (myocardial viability) were also measured. Protocols 1, 2, and 3 had n = 8 hearts, n = 6 hearts, and n = 6 hearts in each group, respectively. RESULTS: In the three protocols, the recoveries of left ventricular developed pressure in the control group, the ICCF group, and the ICCF plus cariporide group, respectively, for protocol 1 were: 26% +/- 3%, 70% +/- 2% (p < 0.05 vs the control group) and 74% +/- 2% (p < 0.05 vs the control group), respectively. For protocol 2 these were: 16% +/- 2%, 55% +/- 1% (p < 0.05 vs the control group), and 70% +/- 3% (p < 0.05 vs the control and ICCF groups), respectively. For protocol 3 these were: 8% +/- 2%, 41% +/- 3% (p < 0.05 vs the control group), and 63% +/- 2% (p < 0.05 vs the control and ICCF groups), respectively. Recovery of left ventricular end-diastolic pressure mirrored that of left ventricular developed pressure in all protocols. In protocol 3, total creatine kinase leakage (international units per gram wet weight) was 88 +/- 12, 47 +/- 4 (p < 0.05 vs the control group), and 17 +/- 1 (p < 0.05 vs the control and ICCF groups), respectively, and triphenyl tetrazolium chloride staining (arbitrary units per gram wet weight) was 0.17 +/- 0.04 in the control group, 0.39 +/- 0.04 (p < 0.05 vs the control group) in the ICCF group, and 0.47 +/- 0.08 (p < 0.05 vs the control group) in the ICCF plus cariporide group, respectively. CONCLUSIONS: Sodium-hydrogen exchanger inhibition with cariporide enhances the myocardial protection afforded by ICCF, with the additive benefit becoming more apparent with increasing severity of the ischemic insult. Sodium-hydrogen exchanger inhibition may provide a significant protective reserve during ICCF, particularly when longer procedures are required.

Animals↗
PubMed1989

An observational study of driver behavior at a protected railroad grade crossing as trains approach.

Observations were made of 57 drivers who approached a rural rail grade crossing in the presence of activated warning flashers signalling an approaching train. Two thirds of the drivers crossed the tracks in front of the approaching trains. All but four drivers, however, slowed perceptibly or stopped prior to crossing. The probability of crossing was seen to vary reliably with distance of the trains from the crossing and the time available to cross (safety margin). It was concluded that, as a group, the drivers' decision to cross was a considered one that was based on an accurate perception of available evidence.

Accident Prevention↗
PubMed1984

Nutritional availability of amino acids from protein cross-linked to protect against degradation in the rumen.

Casein was labelled with pairs of radioactive amino acids, lysine, tyrosine and leucine, one with 14C and the other with 3H, by jugular infusion into lactating goats followed by isolation of the double-labelled casein from the milk. Total milk protein was similarly labelled by jugular infusion of [35S]cystine. U-14C-labelled fraction-1 leaf protein was isolated from lucerne (Medicago sativa) grown in an atmosphere of 14CO2. The proteins were treated with different levels (333 and 667 mmol/kg protein) of formaldehyde, glutaraldehyde and glyoxal. Absorption from the small intestine was measured in sheep with fistulas in the abomasum and terminal ileum, using Cr-EDTA as the digesta flow marker, by introducing radioactive casein into the abomasum. Lysine, tyrosine and cystine became increasingly unavailable for absorption from the small intestine of sheep with increasing levels of aldehyde. At the lower level (333 mmol/kg) the proportions of the amino acids that were unavailable were 0.192, 0.051 and 0.123 respectively. At the higher level of formaldehyde (667 mmol/kg) the corresponding values were 0.335, 0.201 and 0.432 respectively. Leucine was not made unavailable with formaldehyde. The proportions of lysine, tyrosine and leucine that were unavailable were higher, on a molar basis, after treatment of the proteins with the dialdehydes glutaraldehyde and glyoxal than after treatment with formaldehyde. However, the extent of protein protection provided by the dialdehydes in the rumen, measured using an in vitro procedure, was lower.

Amino Acids↗
PubMed2002

Spinal cord protection during aortic cross clamping: retrograde venous spinal cord perfusion, distal aortic perfusion, and cerebrospinal fluid drainage.

OBJECTIVE: We investigated retrograde venous spinal cord perfusion (RVP), with the established adjuncts cerebrospinal fluid drainage (CSFD), and distal aortic perfusion (DAP) in the canine model. We then examined the clinical feasibility of RVP, DAP, and CSFD. DESIGN: Canine study: Twenty dogs were randomized to four treatment groups. All animals underwent 60 min of complete aortic cross-clamp. Group 1 was the control and received only aortic cross-clamp; group 2 DAP and CSFD; group 3 DAP, CSFD, and RVP; and group 4 CSFD plus RVP. Human study: Five patients underwent aortic graft replacement of the descending or thoracoabdominal aorta, while receiving CSFD, DAP, and RVP. RESULTS: Canine study: All animals in groups 1 and 4 awoke paralyzed. One animal each in groups 2 and 3 were paraparetic, with the remaining dogs neurologically intact. Groups 2 and 3 differed from groups 1 and 4 at p < 0.0001. Human study: No mortality or permanent complications were observed in this group. CONCLUSION: While RVP did not reduce neurologic injury, neither did it increase morbidity. In humans the method is technically feasible and free from major problems. Further animal studies and randomized trials are underway at our center.

Aged↗
PubMed1975

Drip retrograde coronary sinus perfusion for myocardial protection during aortic cross-clamping.

Moderate hypothermia is one of the methods utilized for myocardial protection when the aortic root is cross-clamped but not opened. A combination of low-pressure, low-flow retrograde coronary sinus perfusion (RCSP) with oxygenated blood at moderate hypothermia (29 degrees C.) was demonstrated to yield significantly better protection to left ventricular function in dogs than does moderate hypothermia alone. Ventricular function was recorded before and after 1 hour of aortic cross-clamping at identical preloads and heart rates. Aortic pressure was returned to a level as close to base line as possible by constriction of the descending aorta. The average mean aortic pressure of the animals perfused retrograde at 29 degrees C. was returned to within 4 per cent of base line. By contrast, in the animals protected with moderate hypothermia alone, the pressure could be returned only to a level which was 37 per cent lower than base line. In animals protected with moderate hypothermia alone, cardiac output dropped 62 per cent, left ventricular stroke work (LVSW) 75 per cent, and peak dp/dt 44 per cent. In the animals protected with RCSP and moderate hypothermia, the cardiac output dropped 6 per cent, LVSW 9 per cent, and peak dp/dt 5 per cent. The differences in the changes noted between these two groups were significant for LVSW and dp/dt at a level of p less than 0.01 and for cardiac output and aortic pressure at a level of p less than 0.05. These results suggest that RCSP may be indicated when moderate hypothermia is otherwise chosen to be the sole source of myocardial protection.

Animals↗
PubMed1986

Cross-reactive lymphocyte responses and protective immunity against other spotted fever group rickettsiae in mice immunized with Rickettsia conorii.

Lymphocyte proliferation in response to antigens on spotted fever group rickettsiae was used as a method to investigate the group-specific protective immunity to rechallenge characteristic of this group of rickettsiae at the T-cell receptor level. Spleen cells from Rickettsia conorii-immune C3H/HeJ mice proliferated in response to R. rickettsii Sheila Smith, R. sibirica 246, R. australis, and all tested strains of R. conorii (Casablanca, Moroccan, and Malish). Spleen cells from these mice, however, responded poorly or not at all to antigens prepared from the Kaplan or Hartford strain of R. akari. Proliferation of immune T cells maintained as in vitro cell lines showed a similar pattern of reactivity to these antigens; however, response to R. akari was consistently demonstrable. Spleen cells from C3H/HeJ mice immunized with R. akari responded to R. akari and R. conorii antigens as well as antigens from the other spotted fever group rickettsiae. Lymphocytes obtained from lymph nodes draining foot pads infected with R. conorii or R. akari demonstrated cross-reactivity similar to that found with immune spleen cells. If immunization was accomplished with R. conorii antigen emulsified in Freund complete adjuvant, the resulting lymph node cells were able to respond to R. akari antigens. These data suggest that infection with R. conorii induces a population of T lymphocytes that recognize an antigen(s) that also is found on other spotted fever rickettsiae and that may be responsible for cross-protective immunity. This antigen probably is not a major antigen on R. akari.

Animals↗
PubMed1999

Vaccination and protection of pigs against pleuropneumonia with a vaccine strain of Actinobacillus pleuropneumoniae produced by site-specific mutagenesis of the ApxII operon.

The production of toxin (Apx)-neutralizing antibodies during infection plays a major role in the induction of protective immunity to Actinobacillus pleuropneumoniae reinfection. In the present study, the gene encoding the ApxII-activating protein, apxIIC, was insertionally inactivated on the chromosome of a serovar 7 strain, HS93. Expression of the structural toxin, ApxIIA, and of the two genes required for its secretion, apxIB and apxID, still occurs in this strain. The resulting mutant strain, HS93C- Ampr, was found to secrete the unactivated toxin. Pigs vaccinated with live HS93C- Ampr via the intranasal route were protected against a cross-serovar challenge with a virulent serovar 1 strain of A. pleuropneumoniae. This is the first reported vaccine strain of A. pleuropneumoniae which can be delivered live to pigs and offers cross-serovar protection against porcine pleuropneumonia.

Actinobacillus Infections↗
PubMed1997

A comparison of driver behavior at railroad grade crossings with two different protection systems.

An observational study was conducted which compared the behavior of drivers at a railroad-highway grade crossing as trains approached. The effectiveness of a flasher-only protection system was compared with one incorporating flashers and barrier gates for a particular crossing. The addition of the gates significantly reduced the percentage of drivers crossing in front of trains from 67% to 38%. Plots of crossing probabilities showed them reduced as time until train arrival and the distance of the train from the crossing decreased. Train speed did not seem logically related to the probability of crossing perhaps because it is not well perceived. Drivers crossing around barrier gates tended to stop or slow on approach significantly less than those crossing with flashers only. It was suggested that the gates themselves provided an impediment to crossing which forced drivers inclined to cross into making a hurried and sometimes perilous decision. Their behavior was seen as explaining the surprisingly high number of accidents that occur at barrier-gate crossings. Discouraging drivers from driving around barrier gates was seen as essential if safety at these crossings was to be improved. Extending the length of gates and the education of the drivers regarding the law were seen as possible ways of increasing compliance.

Accidents, Traffic↗