Correlation of antibiotic-induced endotoxin release and cytokine production in Escherichia coli-inoculated mouse whole blood ex vivo

Escherichia coli were incubated in mouse whole blood ex vivo supplemented with beta-lactam antibiotics that possessed preferential affinities for penicillin-binding proteins (PBPs). After 4 h, viable bacteria were undetectable in the presence of any of the 3 antibiotics tested, whereas significant increases in colony-forming units were detected in samples not treated with antibiotics. Differential levels of endotoxin in platelet-rich plasma were detected using the limulus amebocyte lysate assay, according to differential antibiotic affinities for the various PBPs. Levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in antibiotic-treated cultures after 8 h of incubation correlated well with the levels of endotoxin at 4 h (r = .96, P < .0001 for TNF-alpha; r = .91, P = .0002 for IL-6). These data indicate that differential affinities of beta-lactam antibiotics for PBPs affect both endotoxin and cytokine responses ex vivo in mouse blood and correlate with in vivo protective efficacy of these antibiotics in gram-negative experimental models.     

Adult and neonatal anti-Gal response in knock-out mice for alpha1,3galactosyltransferase

The hypothalamus-pituitary-adrenal axis of the sheep fetus plays a critical role in fetal development, responsiveness to stress, and initiation of parturition. We have recently reported that the fetal lung contains and secretes significant amounts of immunoreactive adrenocorticotropin (iACTH). The present study was designed to identify the molecular weight profile and the cellular location of iACTH in this tissue. iACTH extracted from fetal lung was immunoprecipitated, electrophoresed, and immunoblotted. Pulmonary iACTH was found in several molecular forms. The largest peptides appeared as doublets, and had molecular weights similar to POMC (32, 33 kD). Smaller peptides appeared in molecular weights (17, 24, and 27 kD) which were not consistent with the post-translational processing of POMC in fetal pituitary, but which were consistent with known processing of POMC by chromaffin granule aspartyl protease. None of the molecular forms of iACTH were glycosylated. Immunohistochemistry revealed that the iACTH was contained within bronchial epithelium and within groups of cells within the parenchyma of the lung. Both of these types of cells are consistent with pulmonary neuroendocrine cells. The distribution of neuroendocrine cells and apparent concordance with the iACTH-positive cells was confirmed by immunostaining for neuron specific enolase, a marker for neuroendocrine cells within the lung. We conclude that the lung contains unprocessed and partially processed POMC within cells known to contain neuropeptides. We speculate that secretion of the POMC-related peptides from these cells is physiologically important in the late-gestation fetus.     

Chronic administration of taurine to aged rats improves the electrical and contractile properties of skeletal muscle fibers

Fimbriae or pili are essential adherence factors usually found in pathogenic bacteria to aid colonization of host cells. Three major structural pilin genes, fimA, sfaA, and papA, from Escherichia coli natural isolates were examined and nucleotide sequence data revealed elevated levels of both synonymous and nonsynonymous site variation at these loci. Examination of synonymous site variation shows a fivefold increase in fimA sites, relative to the housekeeping gene mdh; and similarly the sfaA and papA genes have increased synonymous sites variation relative to fimA. Nonsynonymous site variation is also elevated at all three loci but, in particular, at the papA locus (kN = 0.44). The kN/kS ratio for the three genes are among the highest yet reported for E. coli genes. Regional variation in nucleotide polymorphism within each of the genes reveal hypervariable segments where nonsynonymous substitutions exceed synonymous substitutions. We propose that at the fimA, papA, and sfaA genes, diversifying selection has brought about the increase levels of polymorphism.     

Decoying the cap- mRNA degradation system by a double-stranded RNA virus and poly(A)- mRNA surveillance by a yeast antiviral system

The major coat protein of the L-A double-stranded RNA virus of Saccharomyces cerevisiae covalently binds m7 GMP from 5' capped mRNAs in vitro. We show that this cap binding also occurs in vivo and that, while this activity is required for expression of viral information (killer toxin mRNA level and toxin production) in a wild-type strain, this requirement is suppressed by deletion of SKI1/XRN1/SEP1. We propose that the virus creates decapped cellular mRNAs to decoy the 5'-->3' exoribonuclease specific for cap- RNA encoded by XRN1. The SKI2 antiviral gene represses the copy numbers of the L-A and L-BC viruses and the 20S RNA replicon, apparently by specifically blocking translation of viral RNA. We show that SKI2, SKI3, and SKI8 inhibit translation of electroporated luciferase and beta-glucuronidase mRNAs in vivo, but only if they lack the 3' poly(A) structure. Thus, L-A decoys the SKI1/XRN1/SEP1 exonuclease directed at 5' uncapped ends, but translation of the L-A poly(A)- mRNA is repressed by Ski2,3,8p. The SKI2-SKI3-SKI8 system is more effective against cap+ poly(A)- mRNA, suggesting a (nonessential) role in blocking translation of fragmented cellular mRNAs.     

Dominance of conserved B-cell epitopes of the Plasmodium falciparum merozoite surface protein, MSP1, in blood-stage infections of naive Aotus monkeys

We have shown that conserved B epitopes were immunodominant in animals hyperimmunized with parasite-purified or recombinant merozoite surface protein MSP1 of Plasmodium falciparum. Cross-priming studies also suggested that a conserved T-helper epitope(s) is efficient in inducing the anti-MSP1 antibody response. In this study, we determined whether a similar profile of immune responses was induced during live P. falciparum infections. Naive Aotus monkeys were infected by blood-stage challenge with either one of the two dimorphic MSP1 alleles represented by the FUP and FVO parasites. Sera collected after parasite clearance were analyzed by enzyme-linked immunosorbent assays (ELISAs). Monkeys infected with parasites carrying one allelic form of MSP1 had antibodies that were equally reactive with homologous or heterologous MSP1s. This preferential recognition of conserved epitopes of MSP1 was confirmed by competitive binding ELISAs. Studies with Plasmodium yoelii and P. falciparum show that the C-terminal 19-kDa fragment of MSP1, MSP1(19), is the target of protective immunity. Thus, monkey sera were assayed for recognition with recombinant MSP1(19)s expressing variant and conserved B epitopes. Results of direct and competitive binding ELISAs showed that the anti-MSP1(19) antibodies were also directed primarily against conserved determinants. The similarities between vaccine- or infection-induced antibody responses suggest a possible reciprocal enhancement of the two populations of anti-MSP1 antibodies when a subunit MSP1 vaccine is introduced into populations living in areas where malaria is endemic. This together with previous observations that conserved determinants are important in MSP1-mediated immunity provides an optimistic outlook that a subunit MSP1 vaccine may be effective and practical for field applications in malaria-exposed populations.     

Cyclin D1, another molecule of the year?

AIM: Testicular germ cell tumours may present as metastases in cervical lymph nodes, yet the primary tumours remain clinically occult. The aim of the study is to alert pathologists and clinicians to this uncommon but important presentation and highlight the clues and the diagnostic adjuncts to its correct diagnosis. METHODS: The clinical, cytological, histological, and immunohistochemical features of two patients with germ cell tumour initially presenting as cervical lymphadenopathy were described and analysed. RESULTS: Both patients were young adult males, who were found to have metastatic undifferentiated carcinoma on fine needle aspiration of the enlarged cervical lymph nodes. The tumour cells in both cases were positive for placental alkaline phosphatase (PLAP) and negative for epithelial membrane antigen (EMA). CONCLUSIONS: Clinicians and pathologists should be aware of the possibility of germ cell tumour when encountering a young adult male with metastatic poorly differentiated carcinoma. Positivity for PLAP and negativity for EMA are helpful adjuncts in arriving at the correct diagnosis.     

Antibodies in patients with inflammatory bowel disease and the apparent influence of medications

Patients with inflammatory bowel disease (IBD) are known to have increased antibodies to several food and bacterial antigens. To assess selected isotype contributions in greater detail, we examined the concentrations of IgA, IgG, IgE, and IgG4 antibodies to five selected antigens, two of bacterial and three of food origin. Thirty patients with IBD and thirty matched healthy controls were studied. Most antibodies were increased in IBD patients compared to controls. Statistically significant increases were more frequent in Crohn's disease (CD) than in ulcerative colitis (UC). An unexpected finding was that IBD patients treated with sulfasalazine had statistically higher levels of most IgA antibodies than healthy controls, while steroid treated patients had lower levels. These findings suggest differing effects on the immune systems of IBD patients by each of these commonly used drugs.     

Characterisation of basic proteins from Spiroplasma melliferum using novel immobilised pH gradients

Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) has become the method of choice for efficient separation of complex protein mixtures. Previously, analysis of the Spiroplasma melliferum proteome (protein complement of a genome) has been performed with pH 3-10 and narrow range pH 4-7 IPG gel strips. We report here on the use of novel 18 cm basic (pH 6-11) immobilised pH gradients (IPG) to increase the resolution of protein spots visible within 2-D gels. These gradients were synthesised to emulate the gradient of commercially available IPG gel strips in a 5 cm region of overlap so as to attempt construction of a more complete map of cellular protein expression. Approximately 50 additional gene products were detected from S. melliferum that were not previously well-resolved or visible using wide-range pH 3-10 IPG gel strips. Twenty-seven of these were electrotransferred to polyvinylidene difluoride (PVDF) membrane and analysed by N-terminal protein microsequencing. Protein spots with an initial peak yield of as little as 100 femtomoles (fm) were sequenced to 5-10 amino acid residues, demonstrating the importance of improved sample handling procedures and analytical technologies. Many essential metabolic enzymes were shown to have basic pI, including: glyceraldehyde-3-phosphate dehydrogenase, pyruvate kinase, carbamate kinase and lactate dehydrogenase. A very basic protein (pI approximately 11.0) was identified as uridylate kinase, an enzyme indirectly associated with pyrimidine biosynthesis and thought be absent in some members of the bacterial class Mollicutes. The advent of novel basic (pH 6-11) IPGs has allowed the visualisation of a significantly greater percentage of the 'functional proteome', that portion of the total protein complement of a genome actively translated within a specific time frame, on 2-D electrophoresis gels. This will aid in the characterisation of translated gene products in conjunction with genome sequencing initiatives.     

Verruga peruana: an infectious endemic angiomatosis

Microbial-related dysplastic and neoplastic angiomatous proliferative processes are seen with increased frequency, particularly in the acquired immunodeficiency syndrome (AIDS). The microbial-encoded or -induced mediators of angiopathogenesis in AIDS-associated Kaposi's sarcoma and bacillary angiomatosis are actively being sought. The present review addresses the historical, epidemiologic, clinical, etio- and histopathogenic aspects of the verruga peruana (VP). VP is a disease thus far endemic to high Andean valleys and characterized by dermal angioblastic proliferation in association with reactivation of latent Bartonella bacilliformis organisms. VP closely resembles AIDS-associated angiopathogenic manifestations at the clinical, histopathologic, and etiologic levels and therefore has been proposed as a model for the study of angiogenesis and endothelial cell dysplasia and neoplasia. Moreover, the recent epidemic outbreaks in endemic areas, the increased frequency of international travel to the region, the variable incubation period, and the possibility of not recognizing VP due to its rarity further underscore the relevance of studying this rare disorder and of including it in the differential diagnosis of angiomatous-proliferative disorders.