Salivary and serum procalcitonin and C-reactive protein as biomarkers of periodontitis in United States veterans with osteoarthritis or rheumatoid arthritis

Serum procalcitonin (ProCT) is elevated in response to bacterial infections, whereas high sensitivity C-reactive protein (hsCRP) is a nonspecific inflammatory marker that is increased by excess adipose tissue. We examined the efficacy of ProCT and hsCRP as biomarkers of periodontitis in the saliva and serum of patients with arthritis, which is characterized by variable levels of systemic inflammation that potentially can confound the interpretation of inflammatory biomarkers. Blood and unstimulated whole saliva were collected from 33 patients with rheumatoid arthritis (RA) and 50 with osteoarthritis (OA). Periodontal status was assessed by full mouth examination and patients were categorized as having no/mild, moderate or severe periodontitis by standard parameters. Salivary and serum ProCT and hsCRP concentrations were compared. BMI, diabetes, anti-inflammatory medications and smoking status were ascertained from the patient records. Differences between OA and RA in proportionate numbers of patients were compared for race, gender, diabetes, adiposity and smoking status. Serum ProCT was significantly higher in arthritis patients with moderate to severe and severe periodontitis compared with no/mild periodontitis patients. There were no significant differences in salivary ProCT or salivary or serum hsCRP in RA patients related to periodontitis category. Most of the OA and RA patients were middle aged or older, 28.9% were diabetic, 78.3% were overweight or obese, and slightly more than half were either current or past smokers. The OA and RA groups differed by race, but not gender; blacks and males were predominant in both groups. The OA and RA groups did not differ in terms of controlled or uncontrolled diabetes, smoking status or BMI. The RA patients had been prescribed more anti-inflammatory medication than the OA patients. Our results demonstrate that circulating ProCT is a more discriminative biomarker for periodontitis than serum hsCRP in patients with underlying arthritis. Any elevation in salivary and serum hsCRP due to periodontitis apparently was overshadowed by differences among these patients in factors that influence CRP, such as the extent of inflammation between RA and OA, the extent of adipose tissue, the use of anti- inflammatory medications and smoking status. Although our study showed no differences in salivary ProCT related to severity of periodontitis, this biomarker also may be useful with further refinement.     

Improving the specificity of high-throughput ortholog prediction

Background  

Orthologs (genes that have diverged after a speciation event) tend to have similar function, and so their prediction has become an important component of comparative genomics and genome annotation. The gold standard phylogenetic analysis approach of comparing available organismal phylogeny to gene phylogeny is not easily automated for genome-wide analysis; therefore, ortholog prediction for large genome-scale datasets is typically performed using a reciprocal-best-BLAST-hits (RBH) approach. One problem with RBH is that it will incorrectly predict a paralog as an ortholog when incomplete genome sequences or gene loss is involved. In addition, there is an increasing interest in identifying orthologs most likely to have retained similar function.     

Vaccination equally enables both genetically susceptible and resistant mice to control infection with group A streptococci

There is substantial evidence that host genetic factors are important in determining susceptibility to infection with group A streptococci (GAS). Several studies have revealed that, similarly to humans, a genetic component may be important in determining susceptibility to GAS infection in mice. Thus, C3H/HeN mice are much more susceptible to streptococcal infection than BALB/c mice. We have determined here whether vaccination makes genetically susceptible mice as capable as genetically resistant mice to control GAS infection. Resistant BALB/c and susceptible C3H/HeN mice were immunized either systemically with heat-killed GAS or through the mucosal route with an M protein-based subunit vaccine, and challenged with live bacteria. Vaccination elicited in both mouse strains similar levels of bactericidal anti-GAS IgG antibodies and also antigen-specific mucosal IgA. Vaccination provided mice of both strains with an increased and equal capacity to express immunity against GAS as indicated by the reduced level of bacteria in the organs and the ability of vaccinated mice to survive infection. Protection in vaccinated mice was dependent on the presence of T cell-dependent bactericidal antibodies as shown by the ability of serum elicited in immunocompetent mice but not of serum elicited in T cell-deficient nu/nu mice to passively transfer anti-GAS immunity. In conclusion, the results presented here demonstrated that the presence of anti-GAS specific, T cell-dependent bactericidal antibodies elicited after vaccination overcomes the innate genetic susceptibility of C3H/HeN mice and makes both resistant and susceptible mice equally capable of controlling GAS infection.     

Single-molecule anisotropy imaging

A novel method, single-molecule anisotropy imaging, has been employed to simultaneously study lateral and rotational diffusion of fluorescence-labeled lipids on supported phospholipid membranes. In a fluid membrane composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, in which the rotational diffusion time is on the order of the excited-state lifetime of the fluorophore rhodamine, a rotational diffusion constant, D(rot) = 7 x 10(7) rad(2)/s, was determined. The lateral diffusion constant, measured by direct analysis of single-molecule trajectories, was D(lat) = 3.5 x 10(-8) cm(2)/s. As predicted from the free-volume model for diffusion, the results exhibit a significantly enhanced mobility on the nanosecond time scale. For membranes of DPPC lipids in the L(beta) gel phase, the slow rotational mobility permitted the direct observation of the rotation of individual molecules characterized by D(rot) = 1.2 rad(2)/s. The latter data were evaluated by a mean square angular displacement analysis. The technique developed here should prove itself profitable for imaging of conformational motions of individual proteins on the time scale of milliseconds to seconds.     

Changes in erythrocyte permeability due to palytoxin as compared to amphotericin B

Palytoxin causes within minutes a temperature-dependent K+ loss from human and rat erythrocytes which is followed within hours by haemolysis. It decreases the osmotic resistance in a concentration-dependent manner, so that osmotic influences are negligible for K+ release but considerable in haemolysis. External K+ inhibits the haemoglobin release and Rb+ inhibits the release of K+ and haemoglobin. Ca2+ (over 20 microM) and borate (over 5 microM) enhance the loss of K+ and haemoglobin. With both Ca2+ and borate present, the efficacy of palytoxin is raised about 10 000-fold. Under these conditions, about 15 palytoxin molecules per human cell trigger a 50% K+ loss over a wide range of cell concentrations. The palytoxin effect is reversible. After depletion from K+ by low concentrations of palytoxin, human cells can be refilled with K+ and resealed. The pores formed by palytoxin are small. They allow the entrance of Na+ and choline, whereas inositol is largely excluded and Ca2+, as well as sucrose and inulin, are completely excluded. Amphotericin B resembles palytoxin in its ability to cause a considerable prelytic K+ loss and to form small pores. However, it is about 1000-times weaker than palytoxin, is not inhibited by K+ or Rb+, is not activated by Ca2+ or borate, and has a negative temperature dependence. Thus palytoxin represents a novel type of cytolysin.     

Fibrinogen binding inhibits the fixation of the third component of human complement on surface of groups A, B, C, and G streptococci

Effects of fibrinogen binding to M protein-positive and -negative streptococci on fixation of the third component of human complement (C3) were determined. In all test cultures of serological groups A, B, C, and G fixation of C3 was observed in normal human serum as revealed by quantitative fluorescent immunoassay. Fibrinogen binding inhibited the fixation of C3 on streptococci. The degree of inhibition was proportional to the extent of fibrinogen binding. Thus, inhibition of C3 fixation was most pronounced in strongly fibrinogen-positive streptococci of groups A, C, and G and not demonstrable in fibrinogen-negative cultures of groups C and G. Trypsinization of the streptococci destroyed their capacity to bind fibrinogen and consequently the inhibitory effects on C3 fixation. The carboxymethylated alpha and beta chains of fibrinogen moderately inhibited C3 fixation whereas gamma chain had no influence. These studies may indicate that fibrinogen binding structures other than M protein could also be involved in streptococcal pathogenicity.     

Role of α2-macroglobulin in phagocytosis of group A and C streptococci

Binding of alpha 2-macroglobulin (alpha 2M) to streptococci and its effects on phagocytosis were investigated. Two types of streptococcal binding sites for alpha 2M were observed: Streptococcus pyogenes from human infections interacted only with native alpha 2M whereas S. dysgalactiae from bovine and S. equi from equine infections bound only a complex of alpha 2M with trypsin (alpha 2M-T). Preincubation of S. pyogenes with native alpha 2M substantially enhanced their phagocytosis by human polymorphonuclear neutrophils (PMN) whereas preincubation with alpha 2M-T was without any effect. On the other hand, incubation of S. dysgalactiae and S. equi with alpha 2M-T markedly reduced their phagocytosis by PMN from the respective host species. Native alpha 2M did not affect the phagocytosis of these streptococci. Digestion of the streptococcal binding sites for alpha 2M and alpha 2M-T pronase abolished the enhancement of phagocytosis of S. pyogenes by native alpha 2M as well as the inhibition of phagocytosis of S. dysgalactiae and S. equi by alpha 2M-T. Thus, binding of alpha 2M or its complexes appeared to play a role in streptococcal pathogenicity.     

The IgA-binding β antigen of the c protein complex of Group B streptococci: sequence determination of its gene and detection of two binding regions

The beta antigen of the lbc protein complex of Group B streptococci is a cell-surface receptor which binds the Fc region of human immunoglobulin A (IgA). Determination of the nucleotide sequence of the beta antigen gene shows that it encodes a preprotein having a molecular weight of 130,963 daltons and a polypeptide of 1164 amino acid residues that is typical of other Gram-positive cell-wall proteins. There is a long signal sequence of 37 amino acids at the N-terminus. Four of the five C-terminal amino acid residues are basic and are preceded by a hydrophobic stretch that appears to anchor the C-terminus in the cell membrane. To the N-terminal side of this hydrophobic stretch is a putative cell-wall-spanning region containing proline-rich repeated sequences. An unusual feature of these repeated sequences is a three-residue periodicity, whereby every first residue is a proline, the second residue is alternating positively or negatively charged, and the third residue is uncharged. The IgA-binding activity was approximately localized by expressing subfragments of the beta antigen as fusion proteins. Two distinct but adjacent DNA segments specified peptides that bound IgA, which indicates that the IgA-binding activity is located in two distinct regions of the protein.     

Evolution of antibiotic resistance genes: the DNA sequence of a kanamycin resistance gene from Staphylococcus aureus

The kanamycin resistance gene from Staphylococcus aureus has been sequenced and its structure compared with similar genes isolated from Streptomyces fradiae and from two transposons, Tn5 and Tn903, originally isolated from Klebsiella pneumoniae and Salmonella typhimurium, respectively. The genes are all homologous but, since their common ancestor, have undergone extensive divergence, with more than 43% divergence between the closest pair. The phylogeny of the genes cannot be made congruent to the phylogeny of the taxa from which they were isolated without requiring rather improbable differences in rates. One is therefore led to conclude that there have been multiple occurrences of gene transfer between these species. Thus, although they are homologous, they are neither orthologous nor paralogous. It is suggested that homologous genes of this type be called xenologous.