Reduced Anti-Pseudomonas aeruginosa Activity of a Cephalosporin,Cefodizime, in Rats Whose Neutrophils Were Selectively Depleted by a Monoclonal Antibody

In order to clarify the mechanisms of the in vivo antibacterial activity of a cephalosporin, cefodizime (CDZM), the effect of this antibiotic on Pseudomonas aeruginosa E7 infection was examined in rats whose neutrophils had been selectively depleted by monoclonal antibody RP-3. CDZM was less effective in RP-3-treated rats than in untreated rats. However, treatment of rats with recombinant human granulocyte-colony stimulating factor (rhG-CSF) augmented the in vivo activity of this antibiotic. Furthermore, the in vivo antibacterial activity of two other cephalosporins, cefpimizole (CPIZ) and cefoperazone (CPZ), was bilaterally affected by a rise or fall in the neutrophil number, although to a lesser degree than was the case with CDZM. Taken together, neutrophils play an important role in the in vivo antibacterial activity of certain cephalosporins.     

Urinary pathogenicity of Proteus mirabilis strains isolated from faeces or urine

Urinary and faecal isolares of Proteus mirabilis were studied with respect to a number of bacterial properties as possible virulence factors in the pathogenesis of urinary tract infections: experimental virulence in a mouse model, haemolysin production, haemagglutinating properties, hydrophobicity of the bacterial surface, sensitivity to the bactericidal effect of human serum, serotype and cell invasiveness. Urinary isolates were slightly more virulent than faecal isolates in the mouse model. No other significant differences were found between both groups. So urinary strains seem to be selected from the faecal reservoir mainly on the basis of their prevalence in the faeces and not on the basis of the possession of particular virulence factors.     

Cyclooxygenase-2 inhibition does not impair block bone grafts healing in rabbit model

Success of alveolar reconstructions using onlay autogenous block bone grafts depends on their adequate integration to the recipient bed influenced by a number of local molecules. Considering the fundamental role of cyclooxygenase (COX-2) in bone repair, the aim of this study was to analyze the effect of its inhibition in the integration of endochondral (EC) iliac crest, and intramembranous (IM) calvaria bone grafts. Thirty-two rabbits were divided into 4 groups: Calvaria Control (CC) and Iliac Control—treated with oral 0.9 % saline solution, and Calvarial-NSAID (C-NSAID) and Iliac-NSAID (I-NSAID) groups—treated with oral 6 mg/Kg non-steroidal anti-inflammatory drug etoricoxib. After 7, 14, 30 and 60 days the animals were euthanized and the specimens removed for histological, histomorphometric and immunohistochemistry analysis. At day 60, a tight integration of IM blocks could be seen with the presence of remodeling bone, whereas integration of EC grafts was mainly observed at the edges of the grafts. A significant higher percentage of bone matrix in the interface region of the CC grafts in comparison to C-NSAID only at day 14, whereas no differences were detected comparing the EC grafts. No differences were observed in Runx-2 and vascular endothelial growth factor (VEGF) immunolabeling when comparing CC and C-NSAID groups, while a significant weaker Runx-2 and VEGF labeling was detected in I-NSAID group at day 60. Although some influence was detected in osteogenesis, it is concluded that drug induced inhibition of COX-2 does not impair onlay bone grafts’ healing of both embryologic origins in rabbits.     

γ-Glutamyltranspeptidases in the metabolism of γ-glutamyl peptides in plants

The activity and specificity of γ-glutamyltranspeptidase in immature seeds of some leguminous plants did not reflect the γ-glutamyl peptide pattern     

Conspicuous Growth of Intravenously Inoculated Staphylococcus aureus in Subcutaneously Established Ehrlich Ascites Tumor Tissue of Mice

Intratumoral growth of Staphylococcus aureus was compared with the intrarenal growth, to examine the usefulness of the method as a marker of its pathogenicity. When 5 × 10⁷ CFU/mouse of three derivatives from S. aureus Cowan I with different intrarenal growth were intravenously injected into Ehrlich tumor-bearing mice, they lodged in the tumor tissue at approximately 10³ CFU/0.1 g by 30 min after infection, and grew in the range of 10⁶ CFU/0.1 g to 10⁸ CFU/0.1 g by day 4, regardless of their intrarenal growth capacity. In contrast, S. saprophyticus lodged in both tissues to the same degree as S. aureus, but did not grow at all. The time course of the staphylococcal growth was different between tumor tissue and kidney, suggesting differences in the local responses against S. aureus.     

Signal-sensing mechanisms of the putative osmosensor KdpD in Escherichia coli

The KdpD protein is a membrane-located sensory kinase (or signal transducer) critically involved in the regulation of the kdpABC operon that is responsible for a high-affinity transport system in Escherichia coli. In this study, a set of KdpD mutants, each resulting in a single amino acid substitution around the membrane-spanning regions of KdpD, was isolated. Amino acid substitutions in these KdpD mutants were located non-randomly, particularly within the C-terminal half of the membrane-spanning regions. This set of KdpD mutants exhibited altered transmembrane-signalling properties in response to external K⁺ and other stimuli. In particular, these mutants were found to be insensitive, if not completely, to the K⁺ signal. However, they were able to respond to other stimuli such as high-salt stress, as in the wild type. Therefore, in contrast to the wild type, the cells carrying these mutations exhibited high levels of the steady-state expression of kdp, regardless of external K⁺, provided that high concentrations of ionic solutes were supplemented to the cultures. More interestingly, the set of KdpD mutants could also respond to high concentrations of external non-ionic solutes such as sucrose and D-arabinose, thereby increasing substantially the steady-state expression of kdp in response to the medium osmolarity. Furthermore, it was found that certain chemicals, ethanol, chlorpromazine and procaine, could function as effectors for the KdpD mutants at relatively low concentrations in the media. Based on these findings, we have examined the primary signal(s) that regulates the function of KdpD. We propose here that KdpD can be considered to be an environmental sensor that exhibits sensing mechanisms in response to both the level of K⁺ and the physico-chemical state of the cytoplasmic membrane.