Endopeptidase activities of selected Porphyromonas spp., Prevotella spp. and Fusobacterium spp. of oral and non-oral origin

The ability of three Porphyromonas spp., seven Prevotella spp., seven Fusobacterium spp. and two related Bacteroides spp. (B. levii and B. macacae) to degrade an extensive range of synthetic endo-, amino- and diamino peptidase substrates linked to the fluorescent leaving group 7-amido-4-methylcoumarin (NHMec) was investigated. Many more species than was previously recognized exhibited peptidase activities, albeit at lower levels than those already described for Porphyromonas gingivalis. Detection of chymotrypsin-like activity was dependent on which of three NHMec-linked substrates was used, but all species exhibited degradative activity with at least one of these substrates. Elastase-like activity was detected in all species though not all species reacted with each of the elastase substrates. Glycylprolyl peptidase activity was detected in all of the species tested with the exception of F. mortiferum, F. gonidiaformans, F. naviforme and F. necrophorum. While the detection of peptidase activities does not appear to be useful for the differentiation of species within the genera Bacteroides and Prevotella, its ability to differentiate species of the genus Porphyromonas or Fosobacterium further investigation.     

Normal T lymphocyte function in patients with end-stage renal disease hemodialyzed with 'high-flux' polysulfone membranes

T lymphocyte function was analyzed in patients hemodialyzed with 'high-flux' polysulfone membranes, which have been reported to improve the patients' overall clinical condition and well-being. For comparison purposes, patients treated by the use of 'low-flux' cuprophane membranes were also studied. Peripheral blood white cell counts, numbers of lymphocytes as well as the numbers of T cells and their CD4 and CD8 subsets were within normal range in both patient groups. The absolute number of B cells was slightly decreased in cuprophane-membrane- but not polysulfone-membrane-treated patients. The proliferative response of T lymphocytes after stimulation with optimal concentration of phytohemagglutinin (PHA) was normal in patients treated with 'high-flux' membrane dialysis but significantly reduced in those treated with cuprophane membranes. The generation of interleukin-2 (IL-2) receptor on T lymphocytes after PHA stimulation was normal in the polysulfone-membrane-treated group and slightly impaired in the cuprophane-membrane-dialyzed patients. Production of both IL-2 and interleukin-1, as well as the natural killer cell activity, in patients treated by 'high-flux' membrane dialysis were also comparable to controls. The levels of serum beta 2-microglobulin were significantly elevated in patients-maintained on 'high-flux' dialysis membranes but did not reach the levels seen in patients dialyzed by cuprophane membranes. The beta 2-microglobulin at levels seen in patients on cuprophane dialysis had no effects on activation and proliferation of control lymphocytes in vitro. These results suggest that impaired functional responses of T lymphocytes seen in end-stage disease patients on prolonged hemodialysis with cuprophane membranes are not seen in similar patients hemodialyzed with polysulfone membranes.     

Buffered lidocaine as a local anesthetic: an investigation of shelf life.

STUDY OBJECTIVE: To determine whether buffered lidocaine must be prepared just before use. DESIGN: Randomized, double-blind, prospective trial. SETTING: University hospital. PARTICIPANTS: Twenty-four adult volunteers. INTERVENTIONS: Three buffered lidocaine solutions prepared seven days, one day, and just before use were compared with a control solution. Subjects received 0.5 mL intradermal injections of each solution. Pain of infiltration and extent and duration of anesthesia were measured. MEASUREMENTS AND MAIN RESULTS: Pain of infiltration was less with all buffered solutions than control (P less than .0001). Mean maximum diameter of anesthesia ranged from 29 to 33 mm for the buffered solutions compared with 31 mm for control. Mean duration of anesthesia was 33 minutes for control and 30 minutes for all of the buffered solutions. There was no statistically significant difference in extent or duration of anesthesia for any of the solutions (P greater than .5, beta = .15 for delta = 10%). CONCLUSION: Buffered lidocaine stays effective for up to one week after preparation. It is therefore convenient to use in emergency settings.     

Inhibition of human subgingival plaque protease activity by chlorhexidine.

Subgingival plaque samples from three discrete sites in each of eight patients with adult chronic periodontitis were used to determine the ability of 0.001, 0.01, 0.1 and 1.0 mM chlorhexidine to inhibit bacterial proteolytic activity. This activity was measured by monitoring the increase in relative fluorescence (excitation and emission wavelengths of 495 and 525 nm, respectively) accompanying the degradation of fluorescein isothiocyanate (FITC)-labelled bovine serum albumin or FITC-labelled transferrin. Chlorhexidine at concentrations of as low as 0.01 mM inhibited the proteolytic degradation of both substrates by more than 50%. As the growth of dental plaque bacteria is dependent upon the liberation of nutrients (amino acids, peptides and carbohydrates) from host-derived macromolecules, similar effects in vivo might explain the ability of chlorhexidine to inhibit plaque formation at subminimal inhibitory concentrations.     

Airway hyper-reactivity mediated by B-1 cell immunoglobulin M antibody generating complement C5a at 1 day post-immunization in a murine hapten model of non-atopic asthma

Contact skin immunization of mice with reactive hapten antigen and subsequent airway challenge with the same hapten induces immediate airflow obstruction and subsequent airway hyper‐reactivity (AHR) to methacholine challenge, which is dependent on B cells but not on T cells. This responsiveness to airway challenge with antigen is elicited as early as 1 day postimmunization and can be adoptively transferred to naïve recipients via 1‐day immune cells. Responses are absent in 1‐day immune B‐cell‐deficient JH^?/? mice and B‐1 B‐cell‐deficient xid male mice, as well as in recipients of 1‐day immune cells depleted of cells with the B‐1 cell phenotype (CD19⁺ B220⁺ CD5⁺). As B‐1 cells produce immunoglobulin M (IgM), we sought and found significantly increased numbers of anti‐hapten IgM‐producing cells in the spleen and lymph nodes of 1‐day immune wild‐type mice, but not in xid mice. Then, we passively immunized naive mice with anti‐hapten IgM monoclonal antibody and, following airway hapten challenge of the recipients, we showed both immediate airflow obstruction and AHR. In addition, AHR was absent in complement C5 and C5a receptor‐deficient mice. In summary, this study of the very early elicited phase of a hapten asthma model suggests, for the first time, a role of B‐1 cells in producing IgM to activate complement to rapidly mediate asthma airway reactivity only 1 day after immunization.     

Chitinases and chitinase-like proteins in T(H)2 inflammation and asthma

Chitin is the second most abundant biopolymer in nature, where it protects crustaceans, parasites, fungi, and other pathogens from the adverse effects of their environments, hosts, or both. Because chitin does not exist in mammals, it had been assumed that the chitinases that degrade it are also restricted to lower life forms. However, chitinases and chitinase-like proteins have recently been noted in mice and human subjects. The prototypic chitinase, acidic mammalian chitinase, was also noted to be induced during T(H)2 inflammation through an IL-13-dependent mechanism. It was also shown to play an important role in the pathogenesis of T(H)2 inflammation and IL-13 effector pathway activation and demonstrated to be expressed in an exaggerated fashion in human asthmatic tissues. The finding that chitinases contribute to host anti-parasite responses and asthmatic T(H)2 inflammation support the concept that asthma might be a parasite-independent anti-parasite response.