Incidence and mechanisms of aminoglycoside resistance inPseudomonas aeruginosa serotype O11 isolates

Summary Mechanisms of resistance to five aminoglycoside antibiotics: gentamicin (G), tobramycin (T), netilmicin (N), amikacin (A) and isepamicin (I), were assessed in 16 clinical isolates ofPseudomonas aeruginosa serotype O11, originating from five hospitals in Bratislava. All isolates werein vitro highly resistant to all mentioned aminoglycoside antibiotics (MIC>32 mg/l). Thirteen isolates produced three aminoglycoside-modifying enzymes (AGME), responsible for resistance to the respective aminoglycosides: AAC(6)-I (T, N, A); APH (2) (G, T); APH (3)-VI (I). In addition to this, in four isolates a production of AAC(3)-II (G, T, N) was observed. In three isolates no production of AGME was observed. The strains studied were isolated mainly from urine. Several isolates were able to transfer aminoglycoside resistance by bacterial conjugation toP. aeruginosa 1008 rif^r recipient. The transconjugants from these transfers expressed the same resistance pattern and nearly the same mechanisms of resistance as the donor strains.

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Inzidenz und Mechanismus der Aminoglykosid-Resistenz beiPseudomonas aeruginosa O11-Isolaten

Zusammenfassung Bei 16 klinischen Isolaten vonPseudomonas aeruginosa Serotyp O11 aus fünf Krankenhäusern in Bratislava wurde der Mechanismus der Resistenz gegen fünf Aminoglykosid-Antibiotika untersucht; Gentamicin (G), Tobramycin (T), Netilmicin (N), Amikacin (A) und Isepamicin (I). Alle Isolate warenin vitro hochresistent gegen alle genannten Aminoglykosid-Antibiotika (MHK-Werte >32 mg/l). 13 der Isolate bildeten drei Aminoglykosid-modifizierende Enzyme (AGME), die für die Resistenz gegenüber den entsprechenden Aminoglykosiden verantwortlich waren: AAC(6)-I (TNA): APH (2) (G, T): APH (3)-VI (I). Zusätzlich wurde bei drei Isolaten die Produktion von AAC(3)-II (G, T. N) beobachtet. In drei Isolaten fand sich keine Produktion von AGME. Die untersuchten Stämme waren überwiegend aus Urin isoliert worden. Mehrere der Isolate waren fähig, die Aminoglykosid-Resistenz durch bakterielle Konjugation auf denP. aeruginosa 1008 rif^r Rezipienten zu übertragen. Die Transkonjugate von diesen Übertragungen exprimierten dasselbe Resistenzmuster und wiesen nahezu denselben Resistenzmechanismus auf wie die Spenderstämme.

     

Occupational therapy in the dialysis unit

Occupational therapy is defined by the American Occupational Therapy Association as: the art and science of directing man's participation in selected tasks, to restore, reinforce and enhance performance, facilitate learning of those skills and functions essential for adaptation and productivity, diminish or correct pathology and maintain health.     

No interference of rheumatoid factor(s) with toxoplasmosis IgM determination in infancy

Sera from 263 newborns and infants suspected of congenital toxoplasmosis were tested for the presence of rheumatoid factor (RF) by the latex agglutination test, of which 40 were also tested by the enzyme-linked immunosorbent assay (ELISA). RF was detected in only one serum sample (0.38%), suggesting that false-positive results of the IgM-indirect fluorescent antibody test and the IgM-ELISA due to RF is most unusual in infancy.     

Duodenal and jejunal atresia with agenesis of the dorsal mesentery: "apple peel" small bowel.

Two newborn infants with duodenal and jejunal atresia and agenesis of the dorsal mesentery represent our surgical experience with "apple peel" small bowel or "christmas tree" demormity. The first patient had the typical appearance of this condition. The postoperative course was complicated by hyperbilirubinemia, septicemia, and disseminated intravascular coagulation. The infant is in satisfactory condition 1.5 years after operation. The second patient had agenesis of the dorsal mesentery without spiraling of the bowel around its vascular stalk. The child died after 1 month, with complete absence of extrahepatic bile ducts as seen at a second laparotomy. Neither child had been subjected to gastrostomy.     

Extensive metallosis and necrosis in failed prostheses with cemented titanium-alloy stems and ceramic heads

We describe three prostheses with cemented titanium-alloy stems and Al2O3 ceramic femoral heads which had to be revised after a mean period of implantation of 78 months. In each case, the neck of the prosthesis had been so severely worn that the profile was elliptical rather than circular. There was severe metallosis of the periprosthetic tissues. Metal particles isolated from the tissues were approximately one nanometre in size and the ratios of titanium, aluminium and vanadium in the particles were the same as in the original alloy. Histologically, the high concentration of metal particles masked the presence of high-density polyethylene (HDP) debris, but again particles about one nanometre in size were isolated from the tissues. The severe necrobiosis and necrosis noted were consistent with other reports of the presence of extensive wear particles in periprosthetic tissues. Wear is presumed to have occurred as a result of mismatch between the shape or size of the taper cone and the femoral head, or to changes in the geometry of loading due to migration of the cup. To facilitate early intervention, patients with this design of prosthesis should be monitored radiologically.     

An improved human tumor stem cell assay in ovarian cancer

To evaluate the effect of improved growth rates of ovarian cancers in the human tumor stem cell assay and its value in predicting clinical chemotherapy response, we studied 59 assays in 54 patients. A total of 81.6% of solid specimens and 85.7% of ascites specimens were successfully cultured and yielded an overall growth rate of 82.9%. Simultaneous primary and metastatic cultures were concordant for chemosensitivity in 80% (n = 16). The patients were evaluated for previous chemotherapy, residual volume of tumor, histologic type, and grade, and these were not statistically different between clinical responders and nonresponders. In vivo-in vitro correlations were made in 27 patients and yielded a predictive response of 13% and predictive resistance of 86% at 70% colony inhibition and 31% and 71% at 50% colony inhibition. Improved growth rates therefore did not result in better predictive correlations. The reported experience in ovarian cancer is summarized and the current status of the human tumor stem cell assay is reviewed.     

17β-Estradiol-Induced Synaptic Rearrangements Are Accompanied by Altered Ectonucleotidase Activities in Male Rat Hippocampal Synaptosomes

17β-Estradiol (E2) rapidly, by binding to membrane estrogen receptors, activates cell signaling cascades which induce formation of new dendritic spines in the hippocampus of males as in females, but the interaction with other metabolic processes, such as extracellular adenine nucleotides metabolism, are currently unknown. Extracellular adenine nucleotides play significant roles, controlling excitatory glutamatergic synapses and development of neural circuits and synaptic plasticity. Their precise regulation in the synaptic cleft is tightly controlled by ecto-nucleoside triphosphate diphosphohydrolase (NTPDase)/ecto-5′-nucleotidase (eN) enzyme chain. Therefore, we sought to clarify whether a single systemic injection of E2 in male rats is accompanied by changes in the expression of the pre- and postsynaptic proteins and downstream kinases linked to E2-induced synaptic rearrangement as well as alterations in NTPDase/eN pathway in the hippocampal synaptosomes. Obtained data showed activation of mammalian target of rapamycin and upregulation of key synaptic proteins necessary for spine formation, 24 h after systemic E2 administration. In E2-mediated conditions, we found downregulation of NTPDase1 and NTPDase2 and attenuation of adenine nucleotide hydrolysis by NTPDase/eN enzyme chain, without changes in NTPDase3 properties and augmentation of synaptic tissue-nonspecific alkaline phosphatase (TNAP) activity. Despite reduced NTPDase activities, increased TNAP activity probably prevents toxic accumulation of ATP in the extracellular milieu and also hydrolyzes accumulated ADP due to unchanged NTPDase3 activity. Thus, our initial evaluation supports idea of specific roles of different ectonucleotidases and their coordinated actions in E2-mediated spine remodeling and maintenance.     

Solvation in protein (un)folding of melittin tetramer–monomer transition

Protein structural integrity and flexibility are intimately tied to solvation. Here, we examine the effect that changes in bulk and local solvent properties have on protein structure and stability. We observe the change in solvation of an unfolding of the protein model, melittin, in the presence of a denaturant, trifluoroethanol. The peptide system displays a well defined transition in that the tetramer unfolds without disrupting the secondary or tertiary structure. In the absence of local structural perturbation, we are able to reveal exclusively the role of solvation dynamics in protein structure stabilization and the (un)folding pathway. A sudden retardation in solvent dynamics, which is coupled to the change in protein structure, is observed at a critical trifluoroethanol concentration. The large amplitude conformational changes are regulated by the local solvent hydrophobicity and bulk solvent viscosity.