Evaluation of methods for myocardial protection during extended periods of aortic cross-clamping and hypoxic cardiac arrest.
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Animals↗
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HIV-1 p24 vaccine protects cats against feline immunodeficiency virus infection.
BACKGROUND: Based on previous analysis of feline immunodeficiency virus (FIV)-specific cross-reactive antibodies to HIV-1 p24, cats vaccinated with HIV-1 p24 were evaluated for cross-reactive immunity to FIV. OBJECTIVE: : To determine the level of cross-reactivity that exists between HIV-1 and FIV p24 and its implications for vaccine prophylaxis. METHODS: Specific-pathogen-free cats were immunized three times with HIV-1 p24 in Ribi adjuvant, with (n = 18) or without cytokine (n = 6). Control cats were immunized three times with adjuvant (n = 10) or phosphate-buffered saline (PBS; n = 5). All immunized cats were challenged with either subtypes B or A/B FIV, and monitored by virus isolation, proviral PCR, FIV-specific antibodies, and feline interferon-gamma ELISpot for T-cell activities. RESULTS: Of 18 cats vaccinated with subtype B HIV-1 (HIV-1LAI/LAV, HIV-1UCD1) p24 in Ribi/cytokine adjuvant 14 (78%) were protected against FIV challenges (subtype Agag and Bgag) that infected all 15 adjuvant- or PBS-immunized cats. Furthermore, only three of six (50%) cats vaccinated with FIV p24 in Ribi/cytokine adjuvant were protected against similar FIV challenge. HIV-1 p24 vaccination induced weak cross-reactive antibodies to FIV p24, which did not correlate with vaccine efficacy. However, the peripheral blood mononuclear cells from HIV-1 p24-vaccinated/protected cats at 33-34 weeks post-FIV challenge responded to three T-cell responsive peptides at the carboxyl-terminus of the FIV p24, whereas those cells from the infected control cats had minimal to no responses to the same peptides. CONCLUSIONS: These results suggest the importance of including lentiviral p24 as vaccine immunogen for human AIDS vaccine. Moreover, these results suggest the potential importance of evolutionarily conserved, cross-protective epitopes in vaccine protection.
AIDS Vaccines↗
Heterologous protection against invasive Escherichia coli K1 disease in newborn rats by maternal immunization with purified mannose-sensitive pili.
Heterologous protection against Escherichia coli K1 bacteremia with antibody to purified mannose-sensitive (MS) pili was demonstrated in a neonatal rat model. The serological relatedness of purified MS pili from 17 E. coli K1 clinical isolates was examined by an enzyme-linked immunosorbent assay. Five pilus serogroups were identified, with the pili in each group showing 50% or greater cross-reactivity with the typing serum of the group. The MS pili from 12 of 17 (70%) strains belonged to just two serogroups. Pregnant Sprague-Dawley rats (dams) were immunized with purified pili, and their newborns (pups) were challenged with heterologous E. coli. Bacteremia was significantly reduced when the pili used for immunization were from the same serogroup as the pili expressed by the challenge bacteria. Thus, immunization with C94 pili and challenge with E03 (71% cross-reactivity) or E04 (50% cross-reactivity) resulted in bacteremia rates of 12 of 17 (17%) versus 51 of 79 (65%) in controls and 0 of 75 (0%) versus 28 of 70 (40%) in controls, respectively (P less than 0.001 for each comparison). With lower cross-reactivity, less protection was observed (P less than 0.05 for 22 to 37% pilus serological relatedness). No protection was seen in pups suckled by dams immunized with MS pili having only 5% serological relatedness to the pili on the challenge strain.
Animals↗
Quality control analysis of the potential for asbestos contamination during tissue processing in pathology laboratories.
CONTEXT: Various quality assurance procedures are applied in pathology and analytical microscopy laboratories to ensure accurate results. OBJECTIVE: To assess the potential of cross-contamination of tissue with asbestos fibers and asbestos bodies during the fixation and washing process. DESIGN: Lung tissue from 10 patients with potential asbestos-related disease was evaluated. Samples of fixative, water, and lung tissue from each case were evaluated by light and analytical transmission electron microscopy for asbestos bodies and uncoated asbestos fibers. RESULTS: The lung samples tested contained a range of asbestos bodies and uncoated asbestos fibers. One wash water sample contained one asbestos body. No asbestos bodies or uncoated asbestos fibers were found in any other water or fixative samples. CONCLUSIONS: The absence of uncoated asbestos fibers in wash water or fixative samples argues that the fixation process stabilizes asbestos fibers within tissue and the protocol used in this pathology laboratory protects against cross-contamination of tissue. The finding of one asbestos body in one water sample further supports the efficiency of the protective controls used in the testing methods, since this asbestos body was in the external solution that was being discarded before tissue sampling occurred.
Aged↗
Meta-analysis combining parallel and cross-over clinical trials. III: The issue of carry-over.
In meta-analysis combining results from parallel and cross-over trials, there is a risk of bias originating from the carry-over effect in cross-over trials. When pooling treatment effects estimated from parallel trials and two-period two-treatment cross-over trials, meta-analytic estimators of treatment effect can be obtained from the combination of parallel trial results either with cross-over trial results based on data of the first period only or with cross-over trial results analysed with data from both periods. Taking data from the first cross-over period protects against carry-over but gives less efficient treatment estimators and may lead to selection bias. This study evaluates in terms of variance reduction and mean square error the cost of calculating meta-analysis estimates with data from the first period instead of data from the two cross-over periods. If the information on cross-over sequence is available, we recommend performing two combined design meta-analyses, one using the first cross-over period data and one based on data from both cross-over periods. To investigate simultaneously the statistical significance of these two estimators as well as the carry-over at meta-analysis level, a method based on a multivariate analysis of the meta-analytic treatment effect and carry-over estimates is proposed.
Blood Pressure↗
Photodynamic effects of protoporphyrin on human erythrocytes. Nature of the cross-linking of membrane proteins.
Protoporphyrin-sensitized photooxidation in human red blood cell membranes leads to severe deterioration of membrane structure and function. The membrane damage is caused by direct oxidation of amino acid residues, with subsequent cross-linking of membrane proteins. The chemical nature of these cross-links was studied in model systems, isolated spectrin and red cell ghosts. Cysteine and methionine are not involved in the cross-linking reaction. Further it could be shown that dityrosine formation, the crucial mechanism in oxidative cross-linking of proteins by peroxidase-H2O2 treatment, plays no role in photodynamic cross-linking. Experimental evidence indicated that a secondary reaction between free amino groups and a photooxidation product of histidine, tyrosine or tryptophan is involved in photodynamic cross-linking. This was deduced from the reaction observed between compounds containing a free amino group and photooxidation products of these amino acids, both in model systems, isolated spectrin and erythrocyte ghosts. In accordance, succinylation of free amino groups of membrane proteins or addition of compounds with free amino groups protected against cross-linking. Quantitative data and consideration of the reaction mechanisms of photodynamic oxidation of amino acids make it highly probable that an oxidation product of histidine rather than of tyrosine or tryptophan is involved in the cross-linking reaction, via a nucleophilic addition by free amino groups.
Amino Acids↗
Multiple protective and risk factors for drug use and abuse: cross-sectional and prospective findings.
A conceptual elaboration was developed that incorporates many risk and protective factors, and both direct and moderating (buffering) influences on drug involvement were tested. From prospective data, 14 factors related to drug use were selected and assigned empirically to either a multiple protective index (PFI) or a risk factor index (RFI). Analyses examined the relationships of the RFI, PFI, and their interaction on measures of cigarette, alcohol, cannabis, cocaine, and hard drug use cross-sectionally in late adolescence and later in young adulthood. These same variables were used to predict alcohol, cannabis, and cocaine abuse 8 years later. Vulnerability as measured by the RFI, PFI, and their interaction was highly associated with drug use in adolescence, moderately associated with certain types of drug use in young adulthood, and strongly associated with heightened drug problems in adulthood.
Adolescent↗
Myocardial protection with monophosphoryl lipid-A against aortic cross clamping-induced global stunning.
BACKGROUND: Monophosphoryl lipid-A (MLA) has a late window (24 hours) of cardioprotection against acute myocardial infarction. It is not known whether MLA, administered, 24 hours before surgery, attenuates intraoperative ventricular dysfunction "stunning" associated with aortic cross-clamping and reperfusion during elective cardiac surgery. We determined the dose-response relationship between MLA and ventricular function in a canine model of global myocardial stunning in the absence of necrosis. The role of expression of inducible heat shock protein 70 (HSP 70i) was also investigated. METHODS: Mongrel dogs (n = 32) were intravenously injected with either a vehicle solution or 3, 5, 10, 35 ug/kg MLA. Twenty four hours later, dogs were anesthetized and instrumented, in situ, to monitor the left ventricular performance (the slope of regression between stroke-work and end diastolic length). Tissue samples were obtained to determine HSP70i using immunoblot analysis. After a period of equilibration on cardiopulmonary bypass, the aortic cross-clamp was applied at normothermia for 30 minutes followed by 60 minutes of reperfusion. ATP and catabolites were determined in transmural myocardial biopsies. Triphenyl-tetrazolium chloride (TTC) staining was used to determine myocardial necrosis. RESULTS: MLA treatment did not alter myocardial contractility or ATP metabolism. Global ischemia resulted in about 50% depletion of ATP and remained depressed during reperfusion in all groups. MLA-treated hearts had improved functional recovery in a dose dependent-manner. Significant recovery was observed at the highest dose (35 ug/kg) compared to the control group. Immunoblot analysis demonstrated significant increase in HSP 70i in the MLA-treated hearts. CONCLUSIONS: MLA exhibits a delayed (24 hours) window of protection against myocardial stunning associated with aortic cross-clamping. HSP70i expression may play a role in MLA-mediated cardioprotection.
Adjuvants, Immunologic↗
Synthetic peptide fragments of streptococcal M proteins.
The surface M proteins of group A streptococci prevent phagocytosis by the non-immune host but antibodies subsequently developed against these M proteins opsonize the organism to allow phagocytosis and killing. In some cases, antibodies developed against M proteins are cross-reactive with host tissue and have been implicated in rheumatic fever. Peptide fragments of several serotypes, namely type 24, 5 and 6 M proteins were chemically synthesized and tested for their ability to induce protective and tissue cross-reactive antibodies in rabbits. Two synthetic 35 residue peptides of type 24 M protein, S-CB3 and S-CB7 had previously been shown to evoke high ELISA titers as well as opsonic antibody titers in each of three rabbits. Neither contained host tissue cross-reactive antibodies when examined with human heart tissue. Subpeptides of CB7 were synthesized to identify the smallest protective epitope. Three synthetic subpeptides (S-CB7-(13-35), - (18-35) and - (23-35) C were covalently linked to tetanus toxoid and evoked opsonic antibodies in rabbits and thus protective immunity with no tissue cross-reactive epitopes. Synthetic peptides of the NH2-terminal region of peptide M 5, which is known to contain cardiac tissue cross-reactive epitopes, were also tested. When covalently linked to tetanus toxoid, the synthetic peptide S-M 5 (1-20), but not S-M5 (20-40), evoked antibodies which were protective against type 5 streptococci; no heart cross-reactive antibodies were evoked even when large excesses of the synthetic peptides were injected.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Synthesis and proinflammatory properties of muramyl tripeptides containing lysine and diaminopimelic acid moieties.
The unusual amino acid diaminopimelic acid (DAP) was prepared by cross metathesis of appropriately protected vinyl glycine and allyl glycine derivatives. Catalytic hydrogenation of the cross-coupling product resulted in reduction of the double bond and the removal of protecting groups. The resulting compounds were appropriately protected for the polymer-supported and solution-phase synthesis of muramyl tripeptides 2 and 3, which differ in the amidation of the alpha-carboxylic acids of the isoglutamine and DAP moieties. Muramyl dipeptide (1, MDP), the DAP-containing muramyl tripeptide 3, and the lysine-containing muramyl tripeptides 4 and 5 induced TNF-alpha gene expression without TNF-alpha protein production in a human monocytic cell line. The observed block in translation could be removed by co-incubation with LPS, resulting in an apparent synergistic effect. Compound 2 did not induce TNF-alpha gene expression, neither did it exhibit a synergistic effect with LPS; this indicates that amidation of the alpha-carboxylic acids of the isoglutamine and DAP moieties results in a loss of biological activity. It is proposed that amidation of alpha-carboxylic acids is a strategy that may be used by pathogens to avoid detection by the innate immune system. Furthermore, the pattern recognition receptors Nod1 and Nod2 have been implicated in the possible induction of a synergistic effect of muropeptides with LPS.
Acetylmuramyl-Alanyl-Isoglutamine↗
[The design of air purification system and its effect on surgical ICU].
It is very important to protect air-cross infection and improve air quality in surgical intensive care unit. In the design and effect of "local air condition and purification control system", air microbe colony counter was greatly reduced to 48/m3 (control area), and 105/m3 (uncontrol area), compared to 618/m3 (untreatment), P < 0.01. This system shows stable function, sterilization effect, low cost, and is useful to protect air pollution in surgical intensive care unit.
Air Conditioning↗
Simultaneous carotid endarterectomy and coronary revascularization.
BACKGROUND: Combined cardiac operation and carotid endarterectomy using our technique is an acceptable approach to simultaneous correction of both carotid and cardiac disease. METHODS: From August 1989 to March 1998, 121 consecutive patients underwent combined operations. Of these patients, 112 had coronary artery bypass grafting and carotid endarterectomy, and 9 had coronary artery bypass grafting, carotid endarterectomy, and valve repair or replacement. All patients had a critical stenosis of 85% or more of the carotid artery. Mean age of the patients was 69.2 years; 80 patients were 65 years old or older. There were 88 men and 33 women. Notable risk factors included chronic obstructive pulmonary disease (19.8%), congestive heart failure (28%), preoperative myocardial infarction and unstable angina (66.9%). Of the patients, 20.7% had a stenosis of greater than 50% of the left main coronary artery. The technique used was correction of both the carotid and coronary lesions during a single aortic cross-clamp period using retrograde continuous blood cardioplegia for myocardial protection. Systemic hypothermia to 25 degrees C was used for cerebral protection. RESULTS: Mean cross-clamp time was 118 minutes. Seven patients (5.8%) sustained perioperative cerebrovascular accidents. Two patients had transient ischemic attacks. The procedure-related mortality rate was 5.8%. CONCLUSIONS: The described technique is a good method for simultaneous repair of coronary and carotid lesions in a high-risk group of patients with concomitant disease. We will continue to use it.
Aged↗
Photosensitized cross-linking of erythrocyte membrane proteins. Evidence against participation of amino groups in the reaction.
Exposure of human erythrocyte ghosts (pH 8, 10 degrees C) to visible light in the presence of the photosensitizer, methylene blue, results in a relatively rapid loss of spectrin (bands 1 and 2 on sodium dodecyl sulfate gel electropherograms) and the appearance of high molecular weight cross-linked derivatives. Isolated spectrin also undergoes photosensitized cross-linking, indicating that the reaction is not lipid-dependent. Extensive cross-linking was neither reversed by dithiothreitol nor prevented by prior blocking of SH groups with N-ethylmaleimide, suggesting that cysteine residues are not crucial bridging sites. The possible requirement for NH2 groups, as suggested by previous model studies (Dubbelman, T.M.A.R., de Goeij, A.F.P.M. and van Steveninck, J. (1978) Biochim. Biophys. Acta 511, 141--151), was tested. Succinylation of spectrin protected against cross-linking, but this effect is attributed to the disruption of quaternary structure, as deduced from sedimentation measurements. However, virtually complete blocking of NH2 groups by amidination perturbed overall structure relatively little, and had no effect on cross-linking. Moreover, exogenous amines such as ethylamine, added in large excess to spectrin prior to irradiation, did not interfere with cross-link formation. These results suggest that NH2 groups are not involved in the reaction.
Cross-Linking Reagents↗
Photodynamic protein cross-linking.
Exposure of spectrin to visible light in the presence of a photosensitizer results in photo-oxidation of sensitive amino acid residues and covalent cross-linking of the polypeptides. In a previous paper the cross-linking was ascribed to a secondary reaction between photo-oxidized histidine residues and amino groups. The following observations, described in this paper, are in accordance with this supposition. (1) During illumination of spectrin in the presence of a photosensitizer a pronounced photo-oxidation of histidine residues takes place. (2) Simultaneously a decrease of free amino groups is observed. (3) Semicarbazide protects against cross-linking and is bound to a histidine photo-oxidation product in spectrin. (4) The pH profile of histidine photo-oxidation and subsequent reaction with amino groups is similar to the pH profile of spectrin cross-linking. Amidination of NH2 groups in spectrin does not inhibit cross-linking, as visualized by gel electrophoresis. On the other hand aminidation of denatured myoglobin causes a 50% inhibition of cross-linking. These observations support the notion of NH2-involvement in cross-linking but also demonstrate, that other photodynamic cross-link mechanisms exist.
Amino Acids↗
The effectiveness of topical cardiac hypothermia.
The effectiveness of cooling the subendocardial myocardium by five different methods was evaluated in a group of 100 patients. The most effective and consistent method to cool the heart was by total body hypothermia with the heat exchanger in the cardiopulmonary bypass system. Myocardial temperature became equal to vena caval blood temperature after only a one minute lag. The least effective methods of myocardial cooling were those in which a bath of chilled fluid enveloped the outside surface of the heart, with and without aortic cross-clamping. The drop in ventricular septal temperature was so small that topical hypothermia, by itself, may be worthless. Two methods in wich chilled fluid was perfused through the coronary system produced a significant lowering of myocardial temperature. One of these methods employs coronary perfusion with a cold cardioplegic solution in addition to total body hypothermia. It is our current choice for myocardial protection during cross-clamping of the ascending aorta.
Body Temperature↗
A role for cysteine 3635 of RYR1 in redox modulation and calmodulin binding.
Oxidation of the skeletal muscle Ca(2+) release channel (RYR1) increases its activity, produces intersubunit disulfide bonds, and blocks its interaction with calmodulin. Conversely, bound calmodulin protects RYR1 from the effects of oxidants (Zhang, J.-Z., Wu, Y., Williams, B. Y., Rodney, G., Mandel, F., Strasburg, G. M., and Hamilton, S. L. (1999) Am. J. Physiol. 276, Cell Physiol. C46-C53). In addition, calmodulin protects RYR1 from trypsin cleavage at amino acids 3630 and 3637 (Moore, C. P., Rodney, G., Zhang, J.-Z., Santacruz-Toloza, L., Strasburg, G. M., and Hamilton, S. L. (1999) Biochemistry 38, 8532-8537). The sequence between these two tryptic sites is AVVACFR. Alkylation of RYR1 with N-ethylmaleimide (NEM) blocks both (35)S-apocalmodulin binding and oxidation-induced intersubunit cross-linking. In the current work, we demonstrate that both cysteines needed for the oxidation-induced intersubunit cross-link are protected from alkylation with N-ethylmaleimide by bound calmodulin. We also show, using N-terminal amino acid sequencing together with analysis of the distribution of [(3)H]NEM labeling with each sequencing cycle, that cysteine 3635 of RYR1 is rapidly labeled by NEM and that this labeling is blocked by bound calmodulin. We propose that cysteine 3635 is located at an intersubunit contact site that is close to or within a calmodulin binding site. These findings suggest that calmodulin and oxidation modulate RYR1 activity by regulating intersubunit interactions in a mutually exclusive manner and that these interactions involve cysteine 3635.
Alkylation↗
[Function of the central sterilization office at the Semmelweis Clinic of Conservative Dentistry and Prosthodontics].
In order to prevent cross-infection by blood borne and other pathogens central sterilization department has been constructed in the common building of the Depts. of Conservative Dentistry and Prosthodontics. Instrument sterilization is accomplished in six steps: (1) consolidation and transport of instruments, (2) cleaning, (3) packaging, (4) sterilization, (5) storage, (6) sterilizer monitoring. This process is performed by trained sterilization technicians to ensure that attending faculty, student dentists, clinical staff and patients are protected from cross-infection caused by contaminated dental instruments.
Cross Infection↗
Cross-reactive and serotype-specific antibodies against foot-and-mouth disease virus generated by different regions of the same synthetic peptide.
Synthetic peptides based on the VP1 proteins of two serotypes of foot-and-mouth disease virus (FMDV) and having the general formula C-C-(200-213)-P-P-S-(141-158)-P-C-G induce heterologous as well as homologous protection against challenge. Substitution of the sequence consisting of residues 200 to 213 (200-213 sequence) with a second copy of the homologous 141-158 sequence (i.e., homodimers) resulted in failure of either serotype peptide to protect heterologously. The antiviral and antipeptide titers of sera from guinea pigs immunized with the homodimeric 141-158 peptides showed serotype specificity and, with the data from the heterodimeric peptide vaccines, suggested that the C-terminal 141-158 sequence was more effectively recognized by the immune system than the N-terminal sequence. Whereas heterologous antiviral titers as measured by enzyme-linked immunosorbent assay and virus neutralization tests have not been observed with sera from cross-protected animals, epitope-mapping studies established that there was heterologous recognition of an octapeptide within the 200-213 sequence. That the 200-213 sequence was required for the induction of heterologous protection was also confirmed with a number of peptides, including hybrids based on the 200-213 sequence of one virus and the 141-158 sequence of a second virus. Thus, peptides of the general formula given above induce serotype-specific and serotype-cross-reactive protective antibodies and are unique in their induction of significant levels of heterologous protection, a property which has never been reported for whole FMDV vaccines.
Amino Acid Sequence↗