Pathogenicity of Rhodococcus equi strains possessing virulence-associated 15- to 17-kDa and 20-kDa antigens: experimental and natural cases in pigs

The aim of this study was to determine whether the micronucleus test, using the larvae of a lower invertebrate, the newt Pleurodeles waltl, is suitable for evaluating the overall genotoxicity of polluted water (AFNOR Standard, 1992). The study used the pollutant model benzo(a)pyrene (BaP). After having shown that BaP is metabolized by the larvae, the test was carried out under standard AFNOR conditions. We investigated the relationship between the BaP concentration, spectrofluorometric measurement of liver EROD activity, and two genotoxicity biomarkers: DNA adduct production (32P-postlabeling detection) and micronucleus formation in red blood cells (RBCs) (number of micronucleated RBCs per 1,000). A dose effect was found for all three biomarkers, which were seen to be linearly correlated showing that the biochemical mechanisms occurring in the newt larvae exposed to BaP are similar to those described in higher vertebrates. This result confirms the utility of the test for the evaluation of the overall hazard of a given aquatic environment.     

Serum antibody responses of foals to virulence-associated 15- to 17-kilodalton antigens of Rhodococcus equi

Antibody (Ab) sensitized sciatic nerve Schwann cells (SchC) of 2-day-old rats (SchC/2d) were significantly more susceptible to cytolysis by both heterologous, guinea pig (GP), and homologous rat serum complement (40 +/- 3.8% and 21.2 +/- 3.1%, respectively) than SchC of 6-day-old rats (SchC/6d) (7.9 +/- 5.9% and 2.6 +/- 3.1%, respectively). To determine if resistance to complement (C)-mediated cytolysis correlated with expression of membrane proteins which regulate C activation, we used Western blot and FACS analysis. Binding of specific polyclonal Ab demonstrated similar concentrations of Crry, a regulator of C3 convertase formation, on plasma membranes of SchC 2d and 6d. During C activation, both C3b deposition and iC3b formation were greater on SchC/6d than on SchC/2d and the C3b deposition did not correlate with enhanced cytolysis. In contrast, 2.1-fold more rat CD59, a regulator of C8 and C9 incorporation into C5b-9, detected with Western blot on SchC/6d compared with SchC/2d was confirmed by FACS. Further, both rat and GP C8/C9 lysed SchC/2d expressing human C5b-7 (20.1 +/- 3.7 and 21.6 +/- 4.7%, respectively), while only GP C8/C9 caused cytolysis of 10.7 +/- 4.3% SchC/6d expressing hu C5b-7 and rat C8/C9 did not (0.5 +/- 0.5%). Preincubation of SchC/6d with an F(ab)2 fragment of an mAb to rCD59 with blocking capacity, increased cytolysis mediated by rat serum C more than 6-fold to 16.7 +/- 3.0% but only 1.7-fold (maximum cytolysis 37.4 +/- 11.2%) in SchC/2d. Our data suggest that expression of rat CD59 on SchC increased almost two-fold between postnatal days 2 and 6, and this increased expression on more terminally differentiated SchC is a significant factor in regulating terminal complement complex formation and limiting cytolysis of rat SchC by homologous serum complement.     

Secretory immune response to membrane antigens during Giardia lamblia infection in humans

The secretory immune response in humans infected with Giardia lamblia was studied by using saliva samples and a membrane-rich protein fraction. The membrane fraction, studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, showed 24 antigen bands, ranging from 170 to 14 kDa. Saliva samples from giardiasis patients showed a heterogeneous response against the membrane fraction when they were assayed by immunoblotting. Among the antigens recognized by patient saliva samples, those of 170, 105, 92, 66, 32, 29, and 14 kDa stood out. These antigens were not recognized by saliva samples from healthy individuals. They may be of importance in future studies of protection from or diagnosis of G. lamblia infections.     

Biosynthesis and conformational state of 17-kDa and 27-kDa N-terminal fragments of elongation factor EF-2 in solution

N-Terminal fragments of the rat liver elongation factor EF-2 containing 162 (17 kDa) and 244 (27 kDa) amino acid residues of 857 (95 kDa) residues of the native protein were synthesized in E. coli cells and in a wheat germ cell-free translation system, and their conformations were studied. Both fragments were synthesized as inclusion bodies (nonspecific molecular aggregates). The conformations of the fragments in a solution were studied at neutral pH values by CD, fluorescence spectroscopy, scanning microcalorimetry, viscosimetry, gel-filtration, limited proteolysis, and interaction with monospecific anti-EF-2 antibodies and GroEL/ES molecular chaperone. Under nondenaturing conditions, both fragments existed in a solution as associates within a broad range of molecular masses, contained a considerable amount of elements of the intramolecular secondary structure, and represented globules without rigid tertiary structure (molten globules). A rigid tertiary structure was not formed even after the interaction of the fragments with the GroEL/ES molecular chaperone, thus indicating that the C-terminal fragment is essential for the formation of the rigid tertiary structure. Both fragments contained conformational antigenic determinants similar to those in the whole protein; i.e., despite the absence of the rigid tertiary structure, the fragments contained elements whose structure was similar to that of the corresponding regions in the whole protein.     

Simian varicella virus antibody response in experimental infection of African green monkeys

The humoral immune response to simian varicella virus (SVV) was investigated following primary and secondary experimental infection of African green monkeys. Neutralization and immunoprecipitation assays were used to determine antibody titers to SVV throughout the course of infection. The immune response to specific viral polypeptides was analyzed by immunoprecipitation analysis. The results demonstrate that the simian varicella model offers a useful approach to investigate immune mechanisms in human varicella zoster virus (VZV) infections.     

Homotypic and heterotypic serum neutralizing antibody response to rotavirus proteins following natural primary infection and reinfection in children

Worldwide trials of rotavirus vaccines are currently in progress, but the basis of cross-reactive immunity between rotavirus serotypes is yet to be elucidated. The involvement of the outer capsid proteins, VP7 and VP4, in the production of cross-reactive neutralizing antibody (N-Ab) is unclear, and may be important for the success of animal rotavirus-based candidate vaccines that lack a VP4 of human rotavirus origin. In this study, VP7- and VP4-specific N-Ab was assayed in sera from children experiencing primary (27 children) and/or secondary (14 children) rotavirus infections using human-animal reassortant strains. These reassortants contained genes encoding the major G- and P-types found in human infection, including G1, 2, 3, and 4; or P1A[8], 1B[4], and 2[6]. After primary infection, the N-Ab response to VP7 was generally serotype-specific, whereas the response to VP4 was heterotypic. After reinfection (with the same or different serotypes) there was a significant increase (P=0.0313) in the number of VP7 serotypes seroconverted against with no broadening of cross-reactivity to VP4. Increases in homotypic N-Ab titer, following both primary and secondary infection, were greater against VP7 than VP4, with the seroconversion against VP7 being significantly greater upon reinfection than following primary infection (P=0.0280). In summary, heterotypic N-Ab produced following primary infection appears to be primarily against VP4. However, upon reinfection, VP7 becomes increasingly immunodominant both in terms of cross-reactive N-Ab production and increases in N-Ab titer.     

IgE antibody response of smokers, nonsmokers, and "smoke-sensitive" persons to tobacco leaf and smoke antigens

Serum samples from cigarette smokers, nonsmokers, and persons reporting "smoke sensitivity" were tested for IgE antibodies to tobacco leaf and smoke extracts by the radioallergosorbent test. Results indicated that none of the serum samples tested contained detectable IgE antibodies to smoke extracts. Occasionally, serum specimens from smokers or nonsmokers demonstrated reactivity to leaf antigen. The most significant reaction to leaf antigens was detected in serum from one of the 7 smoke-sensitive subjects tested. These results demonstrate that smoking, nonsmoking, and clinical "smoke sensitivity" are not correlated with the presence of IgE antibodies to tobacco leaf or smoke antigen.     

Qualitative and quantitative analysis of the local and systemic antibody response in mice and humans with Helicobacter immunity and infection

Immunization can prevent or cure an otherwise chronic gastric Helicobacter infection in several different animal models. The goal of the present study was to compare the titers and specificities of local and systemic antibody responses generated by Helicobacter infection and immunization. Protective immunization results in levels of specific gastric antibody significantly lower than induced by infection. However, antibodies from protectively immunized mice preferentially recognize immunodominant proteins of 10-22 and 30 kDa. Immunoblot analysis of infected mice and humans demonstrated that the serum IgA, but not serum IgG, binding profiles yield an accurate profile of the antigenic specificity of the host's gastric IgA. Therefore, serum IgA may be useful in evaluating the immunodominant antigens at the gastric mucosa of infected persons and possibly in determining the immunogenicity of orally applied Helicobacter vaccines.     

The antibody response in sheep vaccinated with experimental Nairobi sheep disease vaccines

The antibody responses to experimental Nairobi sheep disease vaccines have been assayed. The responses to an inactivated methanol precipitated vaccine were comperable with those following infection with virulent virus. The responses to attenuated vaccines were inadequate to protect against challenge with virulent virus.     

Western blot analysis of antibody response to pneumococcal protein antigens in a murine model of pneumonia

Adhesion mechanisms mediated by cytokines have been recognized to play a crucial role in ischaemia-reperfusion mechanisms. Although this phenomenon has been well investigated in organ transplantation, little data is available from upper extremity surgery. Profiles of adhesion molecules (CD11/CD18), key cytokines (TNF-alpha and IL-1), CD4+ and CD8+ lymphocytes, and polymorphonuclear neutrophils were investigated following controlled tourniquet ischaemia of the upper extremity for elective hand surgery. Data suggest that relatively short periods of ischaemia activate a mediator cascade and cell-cell interactions that may be associated with adverse pathopyhsiological effects on peripheral tissues after prolonged ischaemia.     

Multiple sclerosis: altered expression of 70- and 27-kDa heat shock proteins in lesions and myelin

Recent studies have implicated heat shock proteins (HSP) in the pathogenesis of the multiple sclerosis (MS) lesion. Expression of the 73 kDa constitutive HSP (HSC70), the 72 kDa stress-inducible HSP (HSP70), and the 27 kDa small HSP (HSP27) was analyzed in white matter and myelin from central nervous system (CNS) tissue of MS and normal subjects using a combination of immunocytochemistry and quantitative immunoblotting. Plaques of all types were sharply defined by reduced immunostaining for HSC70, and shown by immunoblotting to contain 30 to 50% less HSC70 than surrounding white matter or normal tissue. In contrast, HSP27 was markedly enhanced 2.5- to 4-fold in plaque regions, especially in fibrous astrocytes and in hyperplastic interfascicular oligodendrocytes at the lesion edge. HSP70 was less abundant than HSC70, and no significant differences in HSP70 levels were noted between MS and normal white matter. Myelin isolated from active plaques contained 3- to 4-fold more HSC70 than normal myelin. Pronounced expression of HSP70 and HSP27 was also found in MS myelin, although neither protein was detected in normal myelin. Thus, white matter undergoing immune-mediated destruction in MS was associated with altered distribution and expression of HSC70 and HSP27. These changes may initially serve to protect myelin from further destruction and facilitate repair; however, enhanced expression of HSC70, HSP70, and HSP27 in myelin may subsequently present as additional immune targets involved in the progression of disease.     

Comparison of uptake, oxidation and lipid distribution of 17-iodoheptadecanoic acid, 15-(p-iodophenyl)pentadecanoic acid and 15-(p-iodophenyl)-3,3-dimethylpentadecanoic acid in normal canine myocardium

The kinetics of 17-[123I]iodoheptadecanoic acid (IHDA), 15-(p-[125I]iodophenyl)pentadecanoic acid (pIPPA) and 15-(p-[131I]iodophenyl)-3,3-dimethylpentadecanoic acid (DMIPPA) were investigated in normal canine myocardium. After simultaneous intravenous injection, myocardial biopsy specimens and samples of arterial blood were taken over 80 min. IHDA showed the highest myocardial uptake (995 +/- 248 dpm/mg.mCi versus pIPPA: 785 +/- 197 dpm/mg.mCi, ns) and the largest size of oxidation (74% +/- 4% versus pIPPA: 65% +/- 5%, p < 0.05). Myocardial activity of IHDA decreased with a half-time value of 11.2 min (pIPPA: 13.2 min). Phospholipids were the main lipid fraction into which IHDA was incorporated, whereas pIPPA was predominantly incorporated into triacylglycerols. DMIPPA myocardial activity remained constant during the assay period and instead of being oxidized, DMIPPA was mainly incorporated into triacylglycerols (55% +/- 12%). The myocardium-to-blood ratios of DMIPPA were greater than 10:1. The ratios at peak for IHDA and pIPPA were 4.1:1 and 3.9:1, respectively (both p < 0.0001 versus DMIPPA). In conclusion, differences have been found in the myocardial uptake, oxidation and lipid distribution of IHDA, pIPPA and DMIPPA. DMIPPA is a promising tracer for fatty acid uptake studies with single-photon emission computerized tomography because of its prolonged retention and high myocardium-to-blood ratios.     

Stress exacerbates age-related decrements in the immune response to an experimental influenza viral infection

To test the hypothesis that stress exacerbates immune decrements associated with aging, the impact of restraint stress on immunosenescence was assessed using an experimental model of influenza A/Puerto Rico/8/34 viral infection. Beginning one day prior to infection, male C57BL/6 mice, 3 and 22 months of age, were subjected nightly to 12 hours of restraint stress. In both age groups, restraint induced a comparable increase in serum corticosterone levels. However, in contrast to the 3-month-old controls, serum corticosterone levels in 22-month-old mice returned to baseline slower after removal of the stressor. The characteristic influenza-driven increase in cellularity of the lung and draining lymph node was decreased by age and further suppressed by stress. Natural killer cell activity and virus-specific T helper cell function were also blunted by age and almost completely abrogated by stress. Furthermore, due to the weak immune response to viral infection, aged animals subjected to stress had a lower survival rate than age-matched controls.     

The actions of exogenous dehydroepiandrosterone in experimental animals and humans

Dehydroepiandrosterone (DHEA) is the major adrenal steroid of young adults; however, its physiologic functions, if any, are not known. The purpose of this review is to evaluate the current literature in which DHEA was administered to either humans or experimental animals to discern what these functions might be. Reports are divided into five areas: neurologic, immunologic, cardiovascular, oncologic, and metabolic. Particular attention is paid to the dosage and route of administration. This type of analysis shows that at the lowest doses, DHEA has effects on neurologic and immunologic tissues, suggesting that these two sites may be physiologic targets. DHEA also affects cardiologic and metabolic functions as well as tumor growth, but such actions require higher doses and may reflect 'pharmacologic' activities. It is proposed that DHEA's pattern of activity represents a new class of steroid hormones, the "Regnantoids." Further progress in the endocrinology of this family of steroids may only come when synthetic, long-acting analogs of DHEA are available for in vitro studies to allow correlations between hormone action and receptor binding.     

Visual response to complex facelike patterns by 15- and 20-week-old infants.

In a replication of a study by the author and R. Q. Bell (see record 1967-16464-001), 4 stimulus patterns differing with respect to complexity and facial resemblance were presented to 64 15- and 20-wk-old infants. Consonant with previous findings, a positive linear relationship between fixation time and facial resemblance at both age levels was observed. Looking time was also systematically related to stimulus complexity for all Ss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The immune response to Haemophilus ducreyi resembles a delayed-type hypersensitivity reaction throughout experimental infection of human subjects

Previous work in 3 subjects infected for 2 weeks indicated that experimental infection with Haemophilus ducreyi recruits CD4 cells to the skin at the pustular stage of disease. In order to describe the kinetics of the host response, 23 subjects were infected at 2 sites with a standardized dose of H. ducreyi. Subjects were biopsied 1 or 4 days after inoculation or when they developed a painful pustular lesion (days 7-14). Papules and pustules contained a predominant T cell infiltrate that consisted of CD45RO and CD4 cells of the alpha beta lineage. Both papules and pustules contained mixed or T helper 1 type cytokine mRNA and interleukin-8 and tumor necrosis factor-alpha mRNA. Although the subjects had no history of chancroid, their immune responses resembled delayed-type hypersensitivity reactions that occurred within 24 h of inoculation and persisted throughout the course of experimental infection.     

Histamine levels in the blood of humans experimental animals under normal conditions and following vaccination]

The authors present the results of study of the blood histamine content in intact rabbits and in the animals to which commercial vaccines with a different degree of reactogenic property for man were administered. The blood histamine level was also studied in practically healthy individuals and in those vaccinated with inactivated tick-borne encephalitis vaccine. The blood histamine content varied in intact rabbits from 4 to 10 microgram/ml, averaging 6.4 +/- 0.09 microgram/ml. Animal immunization caused elevation of the blood histamine content correlating with the reactogenic properties of the preparations for man: vaccines with low reactogenic properties--inactivated encephalitis and live measles vaccine produced no significant changes in the index under study; as to the typhoid vaccine with sextatoxoid, and smallpox vaccine with marked reactogenic properties--they stimulated significant histaminemia in rabbits. Revaccination of man against tick-borne encephalitis with the inactivated cultural vaccine caused an increase in the blood histamine content.     

Inconstant association between 27-kDa heat-shock protein (Hsp27) content and doxorubicin resistance in human colon cancer cells. The doxorubicin-protecting effect of Hsp27

To investigate the role of the small 27-kDa heat-shock protein (Hsp27) in the intrinsic resistance of colon cancer cells to doxorubicin, we modified Hsp27 expression either genetically by transfection or pharmacologically by cisplatin treatment. HT-29 cells were transfected with a full-length Hsp27 construct in the sense or antisense orientation. We found a good correlation between cell survival after doxorubicin treatment and Hsp27 content. A similar correlation was found for the thermoresistance of the Hsp27-transfected cells. In contrast, the sensitivity of the different transfected cells to 5-fluorouracil was not modified. cis-Platinum(II)diammine dichloride (cisplatin) treatment of HT-29 or Caco2 cells dramatically increased their Hsp27 mRNA and protein content. Accordingly, the cells became thermoresistant. Contrary to what has been previously assumed, however, cell resistance to doxorubicin was reduced. Our data suggest that the decreased resistance of the cells to doxorubicin may be due to a concomitant increase of topoisomerase II expression, the main target of anthracyclines. In conclusion, although Hsp27 seems to participate in the natural resistance of colon cancer cells to anthracyclines, its increase after cisplatin treatment is not associated with a decreased cytotoxicity to doxorubicin.     

Experimental Taenia solium cysticercosis in pigs: characteristics of the infection and antibody response

The biology of aging is reviewed from the perspective of a medical geneticist. This was the perspective of the late Sam Goldstein, and this article is, therefore, dedicated to his memory. Aging can be defined as the set of phenotypes that escape the force of natural selection. These phenotypes can be modulated by mutation or polymorphism at numerous genetic loci. Given the remarkable genetic and environmental heterogeneity that characterizes our species, it is understandable that there should be considerable variation in patterns of aging. A genetic approach involving the mapping and positional cloning of major loci could provide basic understanding of the mechanisms underlying such variability. Prototypic examples being investigated by the author and his colleagues are the Werner syndrome and dementias of the Alzheimer type. The biochemical genetic analysis of these and other disorders could lead to a new style of medicine based upon preventive approaches tailored to the needs of individuals. Such interventions should ideally involve pediatricians.     

Effects of naltrexone on response to intravenous cocaine, hydromorphone and their combination in humans

This study evaluated the effects of i.v. cocaine, hydromorphone and their combination, and assessed the ability of oral naltrexone, an opioid antagonist, to modulate these effects. Volunteers with cocaine and heroin abuse histories (n = 8) participated in this placebo-controlled, cross-over study while residing on a closed research unit. Daily treatment with capsules containing placebo or naltrexone in ascending doses (3.125, 12.5, 50 and 200 mg) were given for 7-day periods. In thrice weekly experimental sessions, cocaine, hydromorphone and their combination were given in random order. Drug doses were given in an ascending order 1 hr apart as follows: cocaine at 0,20 and 40 mg, hydromorphone at 0, 1.5 and 3.0 mg, and the combination of 0 and 0 mg, 20 mg cocaine and 1.5 mg hydromorphone and 40 mg cocaine and 3.0 mg hydromorphone. Hydromorphone and cocaine produced distinct pharmacodynamic profiles, and the combination produced effects similar to both drugs. In some cases, the magnitude of effects produced by the combination was greater than that produced by either drug alone. Naltrexone produced dose-related blockade of hydromorphone effects, but did not after any of the physiological or subjective effects of cocaine. All naltrexone doses partially attenuated the effects of the combination and this appeared to be attributable to selective opioid blockade. These data do not support the use of naltrexone as a treatment for cocaine abuse, but suggest it may be useful for treating patients with concurrent cocaine and heroin abuse.