Biomedical subjects

Pentti Kuusela

Publications and source records attributed to Pentti Kuusela.

8 recordsLinked to original sources

PubMed2005

Bacterial adherence to titanium surface coated with human serum albumin.

HYPOTHESIS: An albumin coating on titanium implants will inhibit bacterial adhesion on the implant surface. BACKGROUND: Bacterial, protein, and platelet adhesion on otologic implants and tympanostomy tubes is a major reason for implant sequelae and can eventually lead to implant removal. The role of albumin coating of the implant in prevention of protein adhesion on implant surface has already been tested by the authors. In the present study the authors examined the in vitro adherence of Staphylococcus aureus and Pseudomonas aeruginosa on an albumin-coated and uncoated titanium surface. METHODS: Human serum albumin (HSA)-coated and uncoated titanium surfaces were exposed to viable S. aureus and P. aeruginosa and, after washings, photographed by fluorescence microscopy to quantify the adhered bacteria, which was stained with acridine orange. RESULTS: Bacteria in the suspension adhered at a significantly lesser rate to the coated surfaces than to the uncoated surfaces, with overall bacterial adhesion dependent on bacterial concentration. Binding of S. aureus on HSA-coated surfaces was inhibited significantly (from 82 to 95% depending on concentration). Binding of P. aeruginosa was inhibited from 29 to 37%. CONCLUSION: Because albumin coating can reduce bacterial adherence on titanium surfaces in vitro, reduction is possible in bacterial contamination and infection of the HSA-coated titanium implant in vivo.

Bacterial Adhesion↗

PubMed2005

The surface protein Pls of methicillin-resistant Staphylococcus aureus is a virulence factor in septic arthritis.

Pls, a surface protein of certain methicillin-resistant Staphylococcus aureus strains, is associated with poor bacterial adherence to solid-phase fibronectin and immunoglobulin G, as well as with reduced invasion of cultured epithelial cells. Here the importance of Pls for the development of septic arthritis and sepsis was investigated by using a mouse model. Mice inoculated with a pls knockout mutant developed a much milder arthritis and showed less grave weight reduction than mice infected with the wild-type Pls(+) clinical isolate. Also, the pls mutant induced a significantly lower frequency of mortality than the wild-type strain. The bacterial load of the kidneys was larger in mice infected with the Pls(+) strain than in animals challenged with the pls mutant. However, there was no evident inflammatory effect due to the Pls molecule alone, as indicated by knee injection of purified Pls. In conclusion, the results show that Pls is a virulence factor for septic arthritis and sepsis.

Animals↗

PubMed2005

The pls gene found in methicillin-resistant Staphylococcus aureus strains is common in clinical isolates of Staphylococcus sciuri.

pls, a gene found in type I staphylococcal cassette chromosome mec (SCCmec) regions of methicillin-resistant Staphylococcus aureus strains, was present in 12 of the 15 human clinical Staphylococcus sciuri isolates studied. Pls was expressed in the S. sciuri isolates, although at a lower level than in S. aureus. Other parts of SCCmec could also be found in the S. sciuri genome.

Bacterial Proteins↗

PubMed2003

Predictive value of monocyte histocompatibility leukocyte antigen-DR expression and plasma interleukin-4 and -10 levels in critically ill patients with sepsis.

It has been suggested that excessive activation of the anti-inflammatory pathways in sepsis may lead to poor outcome of patients with sepsis. The aim of this study was to test the value of histocompatibility leukocyte antigen (HLA)-DR-expression on blood monocytes and plasma levels of interleukin (IL)-4 and -10 in prediction of hospital mortality in patients with sepsis. Sixty-one critically ill patients with sepsis were prospectively enrolled to this study in two university hospital intensive care units. Survivors (n = 41) and nonsurvivors (n = 20) differed significantly in HLA-DR expression at admission: survivors' median 84% (interquartile range 64%-98%) versus nonsurvivors' median 62% (interquartile range 47%-83%, P = 0.025 by Mann-Whitney test). Similarly, the analysis revealed statistically significant differences between survivors and nonsurvivors in admission plasma IL-10 levels and in admission Sequential Organ Failure Assessment (SOFA) and Acute Physiology and Chronic Health Evaluation (APACHE) II scores, but not in IL-4 levels. The areas under receiver operating curves (AUC) showed that both monocyte HLA-DR expression and plasma IL-4 level showed poor discriminative power in prediction of hospital mortality (AUC < 0.70). Only IL-10 levels on days 1 and 2 showed reasonable predictive power (AUCs 0.706 and 0.725, respectively). The highest AUC values were those of APACHE-II (0.786) and admission SOFA score (0.763). In conclusion, APACHE II and SOFA scores on admission showed better discriminatory power than HLA-DR expression and IL-10 and IL-4 levels in prediction of hospital mortality in critically ill patients with sepsis.

APACHE↗

PubMed2003

Genome diversification in Staphylococcus aureus: Molecular evolution of a highly variable chromosomal region encoding the Staphylococcal exotoxin-like family of proteins.

Recent genomic studies have revealed extensive variation in natural populations of many pathogenic bacteria. However, the evolutionary processes which contribute to much of this variation remain unclear. A previous whole-genome DNA microarray study identified variation at a large chromosomal region (RD13) of Staphylococcus aureus which encodes a family of proteins with homology to staphylococcal and streptococcal superantigens, designated staphylococcal exotoxin-like (SET) proteins. In the present study, RD13 was found in all 63 S. aureus isolates of divergent clonal, geographic, and disease origins but contained a high level of variation in gene content in different strains. A central variable region which contained from 6 to 10 different set genes, depending on the strain, was identified, and DNA sequence analysis suggests that horizontal gene transfer and recombination have contributed to the diversification of RD13. Phylogenetic analysis based on the RD13 DNA sequence of 18 strains suggested that loss of various set genes has occurred independently several times, in separate lineages of pathogenic S. aureus, providing a model to explain the molecular variation of RD13 in extant strains. In spite of multiple episodes of set deletion, analysis of the ratio of silent substitutions in set genes to amino acid replacements in their products suggests that purifying selection (selective constraint) is acting to maintain SET function. Further, concurrent transcription in vitro of six of the seven set genes in strain COL was detected, indicating that the expression of set genes has been maintained in contemporary strains, and Western immunoblot analysis indicated that multiple SET proteins are expressed during the course of human infections. Overall, we have shown that the chromosomal region RD13 has diversified extensively through episodes of gene deletion and recombination. The coexpression of many set genes and the production of multiple SET proteins during human infection suggests an important role in host-pathogen interactions.

Animals↗

PubMed2002

Predictive value of procalcitonin and interleukin 6 in critically ill patients with suspected sepsis.

OBJECTIVE: To evaluate the performance of procalcitonin (PCT), interleukin-6 (IL-6), C-reactive protein, leukocyte count, D-dimer, and antithrombin III at onset of septic episode and 24 h later in prediction of hospital mortality in critically ill patients with suspected sepsis. DESIGN AND SETTING: Prospective, cohort study in two university hospital intensive care units. PATIENTS: 61 critically ill patients with suspected sepsis. MEASUREMENTS AND RESULTS: The outcome measure was hospital mortality. Hospital survivors ( n=41) and nonsurvivors ( n=20) differed statistically significantly on day 1 (admission) in PCT, IL-6, SOFA score, and APACHE II score, and 24 h later in PCT, IL-6, and D-dimer values. AT III, CRP, and leukocyte count did not differ. The areas under receiver operating curves showed reasonable discriminative power (>0.75) in predicting hospital mortality only for day 2 IL-6 (0.799) and day 2 PCT (0.777) values which were comparable to that of APACHE II (0.786), and which remained the only independent predictor of mortality. CONCLUSIONS: Admission and day 2 IL-6, and day 2 PCT, and day 2 D-dimer values differed significantly between hospital survivors and nonsurvivors among critically ill patients with suspected sepsis. However, in prediction of hospital mortality, only the discriminative power of day 2 PCT and IL-6 values, and APACHE II was reasonable as judged by AUC analysis (>0.75).

APACHE↗

PubMed2002

Enhanced activation of bound plasminogen on Staphylococcus aureus by staphylokinase.

Activation of plasminogen (plg) to plasmin by the staphylococcal activator, staphylokinase (SAK), is effectively regulated by the circulating inhibitor, alpha2-antiplasmin (alpha2AP). Here it is demonstrated that intact Staphylococcus aureus cells and solubilized staphylococcal cell wall proteins not only protected SAK-promoted plg activation against the inhibitory effect of alpha2AP but also enhanced the activation. The findings suggest that the surface-associated plg activation by SAK may have an important physiological function in helping staphylococci in tissue dissemination. Amino acid sequencing of tryptic peptides originating from the 59-, 56- and 43-kDa proteins, isolated as putative plg-binding proteins, identified them as staphylococcal inosine 5'-monophosphate dehydrogenase, alpha-enolase, and ribonucleotide reductase subunit 2, respectively.

Amino Acid Sequence↗

PubMed2002

Antibiotic properties of novel synthetic temporin A analogs and a cecropin A-temporin A hybrid peptide.

Temporin A, 18 analogs, and a cecropin A-temporin A hybrid peptide were tested with antibiotic sensitive and resistant bacteria, fungi, human erythrocytes, and in clotting assays. Several peptides were active in these assays, and some analogs (D-TA, W1-TA, and Con-L4,G10) may be useful lead compounds for further antibiotics development. The activity of temporin A was found to be dependent upon several of its structural features, including amino acid composition and sequence, chirality, helicity, and positive charge.

Anti-Bacterial Agents↗