Inhibition of interleukin-8 expression by dexamethasone in human cultured airway epithelial cells.

Interleukin-8 (IL-8) is a neutrophil chemotactic factor expressed in many cell types, including human airway epithelial cells (HAEC). Inhaled corticosteroids are now used increasingly early in the treatment of airway inflammation such as in asthma, and directly interact with HAEC at relatively high concentrations. We have investigated the effect of dexamethasone on IL-8 expression in primary cultured HAEC obtained from transplantation donors. Northern blot analysis was used to measure IL-8 mRNA levels in HAEC, and radioimmunoassay was used to measure IL-8 protein in culture supernatant fluids. We demonstrated that IL-8 was expressed by primary cultured HAEC and that this was enhanced by IL-1 beta and tumour necrosis factor-alpha stimulation, but not by IL-6 or lipopolysaccharide. Dexamethasone suppressed IL-8 mRNA expression and protein synthesis dose-dependently in both resting and stimulated HAEC. The half-life of IL-8 mRNA determined in the presence of actinomycin D was less than 1 hr, and dexamethasone preincubation had no effect on mRNA stability. These results support the view that HAEC may play an important role in the pathogenesis of airway inflammatory diseases, and that glucocorticosteroids may exert their anti-inflammatory effects by blocking IL-8 gene expression and generation in these cells.     

Significance of Abnormal Rabbit Ileal Histology in the Pathogenesis of Diarrhea

In spite of several macroscopic criteria for predicting the presence of histological abnormalities in rabbit ileum, microscopic ileal abnormalities still can escape detection. The effect of histologically abnormal rabbit ileum was evaluated on basal intestinal absorption, on basal absorption, on basal adenylate cyclase activity, and on cholera toxin-induced secretion and cholera toxin-induced stimulation of adenylate cyclase activity. Compared to histologically normal rabbit ileum, the presence of histological abnormalities was associated with decreased basal intestinal water, Na, Cl, and glucose absorption, absent glucose-dependent water absorption, and elevated basal adenylate cyclase activities. However, histologically abnormal rabbit ileum responded to inoculation of purified cholera toxin with stimulation of intestinal water secretion and adenylate cyclase activity similar to that in histologically normal ileum. These data have implications concerning the design of experiments that attempt to study the pathogenesis of diarrheal diseases by correlating changes in ileal transport with changes in ileal mucosal adenylate cyclase activity. In spite of abnormal ileal histology, studies of intestinal secretory states which attempt to define the role of adenylate cyclase in secretory processes can be performed provided animals are used as their own controls. However, when groups of animals are compared, the presence of an histologically abnormal ileum can cause changes in basal and intestinal secretagogue-stimulated ileal water and electrolyte transport and in basal and intestinal secretagogue-stimulated mucosal adenylate cyclase activity which can lead to erroneous conclusions if the presence of the abnormal ileal histology is not considered.     

Corynebacterium riegelii sp. nov., an Unusual Species Isolated from Female Patients with Urinary Tract Infections

Four strains of an unknown coryneform bacterium were isolated in pure culture from females with urinary tract infections. Strong urease activity and the ability to slowly ferment maltose but not glucose were the most significant phenotypic features of this catalase-positive, nonmotile, nonlipophilic, rod-shaped bacterium which served to distinguish it from all other presently defined coryneform bacteria. Chemotaxonomic investigations demonstrated that the unknown bacterium belonged to the genus Corynebacterium. Comparative 16S rRNA gene sequence analysis revealed that the isolates were genealogically identical and represented a new subline within the genus Corynebacterium, for which the designation Corynebacterium riegelii sp. nov. is proposed. The type strain of Corynebacterium riegelii is CCUG 38180 (DSM 44326, CIP 105310).     

Development of suppressor T cells in mice heavily infected with mycobacteria

Specific pathogen-free B6D2 mice were infected intravenously with 10(8) viable BCG, M. habana or M. simiae and the level of tuberculin hypersensitivity to 2.5 micrograms PPD or cytoplasmic protein antigens (CPA) prepared from the other organisms was determined using the footpad swelling test with increasing time after infection. This was correlated with the growth or persistence of mycobacterial populations within the liver. Spleen cells were removed from these infected mice and the level of blast transformation following exposure to PHA, PPD or M. habana or M. simiae CPA was measured in vitro. Early in the mycobacterial infections (day 14) thymidine incorporation by the spleen cells was significantly enchanced followed by a profound depression in incorporation rates as the infection progressed. The mechanism of this depressed response involved the production of suppressor T cells in the spleen. In the case of the M. simiae or M. habana infection, cells capable of mediating suppression were still present even after 12 months of infection. In the BCG infection, suppressor T cells declined with time so that by 4 months incorporation rates were back to normal and suppressor cells were no longer detectable in the spleens of the infected animals.     

Actinomyces cardiffensis sp. nov. from human clinical sources

Eight strains of a previously undescribed catalase-negative Actinomyces-like bacterium were recovered from human clinical specimens. The morphological and biochemical characteristics of the isolates were consistent with their assignment to the genus Actinomyces, but they did not appear to correspond to any recognized species. 16S rRNA gene sequence analysis showed the organisms represent a hitherto unknown species within the genus Actinomyces related to, albeit distinct from, a group of species which includes Actinomyces turicensis and close relatives. Based on biochemical and molecular genetic evidence, it is proposed that the unknown isolates from human clinical sources be classified as a new species, Actinomyces cardiffensis sp. nov. The type strain of Actinomyces cardiffensis is CCUG 44997(T).     

Worldwide genomic diversity of the human papillomaviruses-53, 56, and 66, a group of high-risk HPVs unrelated to HPV-16 and HPV-18

Among more than 200 human papillomavirus (HPV) types presumed to exist, 18 "high-risk" HPV types are frequently found in anogenital cancer. The best studied types are HPV-16 and 18, which are only distantly related to one another and form two separate phylogenetic branches, each including six closely related types. HPV-30, 53, 56, and 66 form a third phylogenetic branch unrelated to HPV-16 and 18. Worldwide comparison of HPV-16 and 18 isolates revealed a distribution of variant genomes that correlated with the geographic origin and the ethnicity of the infected cohort and led to the concept of unique African, European, Asian, and Native American HPV-16 and 18 variants. Here, we address the question whether similar phylogenies are found for HPV-53, 56, and 66 by determining the sequence of the long control regions (LCR) of these HPVs in samples from Europe, Asia, and Africa, and from immigrant societies in North and South America. Phylogenetic trees calculated from point mutations and a few insertions/deletions affecting 2-4.2% of the nucleotide sequences were distinct for each of the three HPVs and divergent from HPV-16 and 18. In contrast to the "star-phylogenies" formed by HPV-16 and 18 variants, 44 HPV-53 isolates represented nine variants, which formed two deep dichotomic branches reminiscent of the beginning split into two new taxa, as recently observed for subtypes of HPV-44 and 68. A total of 66 HPV-56 isolates represented 17 variants, which formed three branches preferentially containing European, Asian, and African variants. Variants of a fourth branch, deeply separated from the other three, were characterized by a 25 bp insertion and created a dichotomy rather than star-like phylogeny. As it contained isolates from cohorts in all continents, it may have evolved before the spread of humans into all continents. 18 of 31 HPV-66 isolates represented the prototype clone, which was found in all parts of the world, while the remaining 13 clones formed 11 branches without any geographic association. Our findings confirm the notion of a quantitatively limited genomic diversity of each HPV type with some correlation to the geographic origin of the sample. In addition, we observed in some variants of these three HPV types mutations that affect the amino acid sequence of the E6 oncoproteins and the L1 capsid protein, supporting the possibility of immunogenic and oncogenic diversity between variants of any HPV type.     

DNA vaccination against tuberculosis: expression of a ubiquitin-conjugated tuberculosis protein enhances antimycobacterial immunity

Genetic immunization is a promising new technology for developing vaccines against tuberculosis that are more effective. In the present study, we evaluated the effects of intracellular turnover of antigens expressed by DNA vaccines on the immune response induced by these vaccines in a mouse model of pulmonary tuberculosis. The mycobacterial culture filtrate protein MPT64 was expressed as a chimeric protein fused to one of three variants of the ubiquitin protein (UbG, UbA, and UbGR) known to differentially affect the intracellular processing of the coexpressed antigens. Immunoblot analysis of cell lysates of in vitro-transfected cells showed substantial differences in the degradation rate of ubiquinated MPT64 (i.e., UbG64 < UbA64 < UbGR64). The specific immune response generated in mice correlated with the stability of the ubiquitin-conjugated antigen. The UbA64 DNA vaccine induced a weak humoral response compared to UbG64, and a mixed population of interleukin-4 (IL-4)- and gamma interferon (IFN-gamma)-secreting cells. Vaccination with the UbGR64 plasmid generated a strong Th1 cell response (high IFN-gamma, low IL-4) in the absence of a detectable humoral response. Aerogenic challenge of vaccinated mice with Mycobacterium tuberculosis indicated that immunization with both the UbA64- and UbGR64-expressing plasmids evoked an enhanced protective response compared to the vector control. The expression of mycobacterial antigens from DNA vaccines as fusion proteins with a destabilizing ubiquitin molecule (UbA or UbGR) shifted the host response toward a stronger Th1-type immunity which was characterized by low specific antibody levels, high numbers of IFN-gamma-secreting cells, and significant resistance to a tuberculous challenge.     

Study of T-lymphocyte subsets of healthy and Mycobacterium avium subsp. paratuberculosis-infected cattle.

The relative contributions of T-lymphocyte subsets to host defense in cattle infected with Mycobacterium avium subsp. paratuberculosis is reported. The subsets were purified with appropriate monoclonal antibodies and a magnetic bead column separation system, and their purity was verified by flow cytometry. Biological activity of each subset, expressed as lymphoproliferation and gamma interferon (IFN-gamma) production, was measured in response to phytohemagglutinin (PHA) and an M. avium antigen preparation (A-PPD). IFN-gamma was measured by antibody capture enzyme-linked immunosorbent assay. The results showed a correlation between proliferation and IFN-gamma production in response to A-PPD but not to PHA. In response to PHA, CD4+ lymphocytes were the most prolific producers of IFN-gamma. CD8+ lymphocytes produced IFN-gamma to a lesser extent, whereas gammadelta+ T lymphocytes produced little or no IFN-gamma. Differences observed between the amount of IFN-gamma produced by CD4+ versus CD8+ cells and CD4+ versus gammadelta+ cells were significant (P < 0.01), but those between peripheral blood mononuclear cells (PBMC) and CD4+ T cells were not. Similar responses to A-PPD were observed except that PBMC produced higher levels of IFN-gamma than did CD4+ T cells. These data for cattle are similar to observations made for other animal species, where CD4+ cells are the major type of T lymphocytes producing IFN-gamma. They further suggest that whatever the role gammadelta+ T cells may play in paratuberculosis, it is not likely to be mediated by IFN-gamma production.     

Rapid, sensitive, competitive serologic enzyme-linked immunosorbent assay for detecting serum antibodies to bovine herpesvirus type 1.

An enzyme-linked immunosorbent assay (ELISA) for the detection of cattle antibodies to bovine herpesvirus type 1 was developed on the basis of competition between serum antibody and a virus-neutralizing mouse monoclonal antibody. The assay showed improved sensitivity over the virus neutralization (VN) test and over an enhanced VN test in which incubation of antibody-virus mixtures was carried out for 24 h. With the ELISA, antibodies in sera from experimentally infected cattle were detected earlier after infection and showed more rapid increases in levels. A comparison of the ELISA with the VN tests by using a set of 85 field sera with low levels of antibodies demonstrated that the ELISA was the most sensitive test, detecting 10 positive serum samples that were negative by the VN tests. The ELISA was inexpensive, rapid, and highly reproducible and showed a significant improvement in sensitivity over VN tests.     

How useful is weight reduction in the management of hypertension?

A group of previously untreated obese hypertensive patients were started on a weight reduction programme supervised by two dietitians working in a general practice surgery. It was stressed from the beginning of the programme that reducing blood pressure was the purpose of the diet. The results of follow-up after six months are presented together with results for a control group of obese hypertensive patients not receiving dietary advice or drug therapy, but being followed by the general practitioner. The weight, systolic blood pressure and diastolic blood pressure of the dieting hypertensive group were significantly lower than those of the non-dieting group after six months. However, the drop-out rate was significantly higher for the dieting group than for the non-dieting group.

The results of a separate comparison between a control group of obese normotensive patients following the same dietary programme and the group of dieting obese hypertensive patients are also presented. Attendance rates and weight loss achieved were significantly better for the hypertensive group than for the normotensive group after 12 months.

Weight reduction appears to be an effective first-line therapy for approximately 50% of obese patients with mild to moderate hypertension, and raised blood pressure appears to provide motivation for such patients to attend a dietitian's clinic and to lose weight.