Detection of right ventricular ischaemia during coronary surgery by means of a right precordial lead

This study was designed to determine the intra-operative incidence of right-sided ventricular ischaemia and any association with left ventricular ischaemia. In 60 patients, undergoing coronary artery bypass grafting surgery, a right-sided precordial lead V5R was used. ST segment deviation of more than 1 mm in V5R was considered significant for myocardial ischaemia. Right ventricular ischaemia occurred in 14 patients (23.3%) but was not associated with left ventricular inferior wall ischaemia. In 4 patients (6.6%) presenting with right ventricular ischaemia, ischaemia of the left inferior wall also developed but in all cases was transient and disappeared by the end of surgery. No myocardial infarction was detected in the post-operative period. The present study showed that the use of a right-sided lead may improve intra-operative electrocardiographic monitoring, by revealing ischaemia in those patients in whom ECG abnormalities were not detected by conventional leads. The transient right ventricular ischaemia recorded in this study was probably related to a reduced hypothermic protection of the right ventricle during aortic cross clamping.

The role of tissue colonization and bacterial resistance in recurrent tonsillitis

Unsuccessful medical therapy for treatment of acute tonsillitis frequently results in onset of recurrent or chronic forms rendering surgical treatment necessary. We have studied some of the factors involved in the evolution of these chronic or recurrent forms and, in particular, the distribution of different bacterial strains in tonsillar tissue, their response to treatment with antibiotics and mechanisms of bacterial resistance. The distribution of bacterial flora (saprophytic and pathogenic) present on the surface of the tonsils, in the crypts and in the tonsillar tissue was studied in a control population of 30 children (20 boys and 10 girls) aged between 2-13 years, all affected with chronic tonsillitis and submitted to tonsillectomy. The same study was performed in a group of 80 sex and aged matched children, also presenting with chronic or recurrent tonsillitis and treated with amoxicillin or amoxicillin-clavulanic acid or cefaclor or clarithromycin 72 h before surgery. The 80 subjects were randomly divided into four groups so that each antibiotic was tested on 20 subjects. The distribution of the bacterial population on the surface of tonsillar tissue, in the crypts and in the deeper tonsillar tissue is of particular interest concerning the affinity of bacteria to the different tissue areas. In particular the interaction between crypt and tonsillar core, which could be a factor involved in the process of worsening of bacterial infection in the tonsils, is evidenced. The four antibodies tested showed different abilities to eradicate infection: Haemophilus influenzae was found to be the most resistant germ to antibiotic therapy and was thus the most frequent cause of recurrent infections. The characteristics and the mechanisms of adherence and resistance to beta lactam antibiotics were also analysed.

Extended-spectrum beta-lactamases conferring resistance to monobactams and oxyimino-cephalosporins in clinical isolates of Serratia marcescens

We studied antibiotic resistance patterns and extended-spectrum beta-lactamases (ES beta Ls) production in Serratia marcescens strains isolated in our hospital during 1993. We examined 210 S. marcescens isolates. Of these, 172 were obtained from 49 patients admitted to an intensive care ward; 157 out of 172 were obtained from February to October and presented the same pattern of antibiotic resistance, including monobactams and oxyimino-cephalosporins. The remaining 15 out of 172 isolates (obtained from September to December) were susceptible to all drugs tested, with the exception of first generation cephalosporins. Thirty-eight additional isolates were recovered, during the same period, from 28 patients admitted to wards other than the intensive care unit; also these strains showed the high susceptibility pattern reported above. Epidemic strains of S. marcescens produced three different types of beta-lactamase with pI 5.4, 5.5, and 8.4. In contrast, non-epidemic strains produced only one type of beta-lactamase with pI 8.4. Conjugation experiments showed that the beta-lactamases having a pI of 5.4 and 5.5 (but not the one with pI 8.4) were plasmid-mediated. Since the beta-lactamase with pI 5.5 was capable of hydrolyzing monobactams and oxyimino-cephalosporins it was classified as ES beta L. Electrophoretic analysis showed that plasmids obtained from multiresistant strains were of about 54 kb; these plasmids appeared also to code for aminoglycoside resistance. Our data indicate that the plasmid-mediated production of ES beta Ls may contribute to the epidemic spread of Serratia marcescens in high-risk wards.

Outbreak of extended-spectrum beta-lactamase producing Serratia marcescens in an intensive care unit

Serratia marcescens has recently been identified as an important etiological agent in nosocomial infections, and is considered to be an opportunistic pathogen agent in immunosuppressed patients undergoing long periods of intensive care. Research carried out in 1991 and 1992 showed that it was of epidemiological relevance in only 1-2% of clinical isolates at the Ospedale di Circolo, Varese, Italy. However, between 7 February and 11 October 1993, the incidence of cases attributable to S. marcescens had increased to 5%; 157 strains of Serratia marcescens were isolated from clinical specimens of 43 patients admitted to an intensive care unit; these strains, characterized by epidemic spread, showed the same pattern of multiresistance to antibiotics including monobactams and oxyimino-cephalosporins. During the same period 23 isolates were also recovered from 18 patients admitted to wards other than the intensive care unit; these strains, characterized by a wide range of antibiotic susceptibility, were also sensitive to beta-lactam antibiotics with the exception of first generation cephalosporins. The production of extended-spectrum beta-lactamases (ES beta Ls) and their genetic determinism were studied. All the epidemic strains of S. marcescens resistant to ceftazidime, cefotaxime, ceftriaxone and aztreonam produced three different beta-lactamases with pI 5.4, 5.5 and 8.4 respectively. In contrast, non-epidemic strains produced only a beta-lactamase with pI 8.4. The beta-lactamase with pI 5.5 was plasmid-mediated, hydrolizing ceftazidime and aztreonam, showing it to be an ES beta L; while the beta-lactamase with pI 5.4, although plasmid-mediated, did not hydrolize monobactams or oxyimino-cephalosporins.(ABSTRACT TRUNCATED AT 250 WORDS)

Extended-spectrum beta-lactamases from Klebsiella pneumoniae strains isolated at an Italian hospital

Eighteen strains of Klebsiella pneumoniae recently isolated from hospitalized patients were resistant or moderately resistant to oxyimino-cephalosporins (ceftazidime and/or cefotaxime), aztreonam, cefoxitin and all but one were susceptible to imipenem. Analysis of enzymes produced by these clinical isolates revealed a wide pattern of extended-spectrum beta-lactamases. All isolates produced one or more beta-lactamases that were characterized preliminarily by their isoelectric point. Strains isolated early were from patients in the Intensive Care Unit and produced an ES beta-lactamase with an apparent pI of 7.6, whereas the later isolates were from surgical and medical wards of the same hospital and produced ES beta-lactamases with apparent pI of 8.2 and 8.4, respectively. This suggests the emergence of SHV-5 and MIR-1 beta-lactamases in our hospital. Agarose gel electrophoresis of plasmid DNA revealed the presence of a similar plasmid of approximate size 60 Kb in all isolates.

[An analysis of a case series of 342 short-stature patients examined by the Tanner-Whitehouse 2 (TW2) method]

342 short-stature patients were examined to assess the agreement between anagraphic and bone ages. 190 men and 152 women (age range: 0 to 17.5 years) underwent conventional radiographs of the left wrist. The radiographs were studied with the TW2 method which provides an index of the skeletal maturity of short and long bones and a global index of the hand. The bone ages thus obtained were compared with anagraphic ages. Patients' statures were compared with their parents' ones. Finally, radiation exposures were evaluated. Anagraphic and bone ages were in agreement in 199 patients and in disagreement in 220. Three patients were adult. The short stature in 78 patients was in agreement with their parents' one, while 253 patients had at least one parent with normal stature. No comparison could be made in 11 patients. In conclusion, TW2 is a simple method to calculate bone age (in months and years) and to select the patients to submit to further examinations and to hormone therapy.

Assisted evaluation of antibiotic resistance development in Pseudomonas aeruginosa from intensive care units

421 strains of Pseudomonas aeruginosa were isolated from patients admitted to intensive care units and tested with automated systems for sensitivity to 21 antimicrobial agents. Data were collected in a database for evaluation and monitoring of resistance development. Results showed that assisted monitoring of antimicrobial resistance gives continuously updated information, with particular attention to the different local therapeutical schedules. It is therefore advisable that clinicians constantly exchange information with the microbiology laboratory through a hospital information system in which data from different laboratories are pooled in real time.

[The use of systemic phosphocreatine in heart surgery]

Phosphocreatine (PC) has been widely used in cardiac surgery as a component of cardioplegic solutions because of its positive effects in preventing ischemic heart damage; we have researched the efficacy of PC in cardiac surgery when infused through the intravenous route before and after cardiac arrest. Two groups of patients who had undergone aortocoronary by-pass grafts were matched: group A (20 patients) did not receive any particular treatment; PC was administered intravenously to patients in group B after the induction of anaesthesia, immediately prior to cardiac arrest and after the release of aortic cross-clamp. To test the efficacy of the drug, the following parameters were evaluated: the recovery as the incidence of low cardiac output and/or need of inotropic drugs; dysrhythmias; electrocardiographic signs of myocardial ischemia or infarction; release of cardiac necrosis enzymes. Treated patients were found to have a better recovery, a lower incidence of dysrhythmias, an easier resumption of normal sinus rhythm with a lower number of electric defibrillations and a significantly lower release of cardiac enzymes. It can be therefore said that PC has a marked protective effect on myocardial anoxia in cardiac surgery, even when administered intravenously.

Antibiotic susceptibility patterns surveillance and clinical distribution of Enterobacteriaceae

3700 strains of Enterobacteriaceae clinical isolates were tested by automated devices for susceptibility to several antimicrobial agents widely used in clinical practice. Amikacin demonstrated the greatest in vitro activity whereas ampicillin and mezlocillin were the least active. Finally gentamicin and nalidixic acid had a similar activity to recently introduced cephalosporins. The bacterial species widely isolated were grouped in three clusters according to the clinical body site of isolates: several discrepancies emerged from the study of antibiotic susceptibilities of strains obtained from different body site sources. Source could be correlated with bacterial pattern of resistance.

Physico-chemical properties of amphoteric, isoelectric, macroreticulate buffers

We report here the properties of a new family of resins possessing an amphoteric character and able to strongly buffer at their pI values. They have been adopted as carriers for growth of cells in tissue culture and for hydroponics (Righetti et al. 1991; J. Biotechnol. 17, 169-176) but it is to be expected that such resins could have interesting chromatographic applications. It has been found that such beads [made by incorporating a pK 6.2 weak acrylamido base and a pK 4.6 weak acrylamido acid in a 2:1 ratio (thus with a pI of 6.2) into a neutral polyacrylamide backbone], independently from their initial conditioning (acid- or base-washed), spontaneously seek their equilibrium position (pI value) upon washing off excess titrant. Thus, upon potentiometric titration, they are seen to buffer in both directions of the pH scale (contrary to the behaviour of a pure carboxyl or a pure amino surface, which will exhibit only unidirectional buffering power). From the behaviour of these amphoteric beads when polymerized in the absence or in the presence of salts (0.2 M NaCl), it is hypothesized that, for exerting buffering power, both the buffering ion and its counterion must be incorporated non-randomly in the chain, but as a couple or in close proximity. Upon random incorporation of the two ions, buffering power is lost.

Immunoblot typing of oxacillin-resistant Staphylococcus aureus clinical isolates

Recently an immunoblotting system was developed for typing oxacillin-resistant Staphylococcus aureus. Oxacillin-resistant S. aureus (ORSA) isolates recovered during a 4-month period from premature new-borns division of University Hospital of Pavia, with several antimicrobial susceptibility patterns, were evaluated with this typing scheme. Immunoblotting was found to be a useful method with good reproducibility and the ORSA strains isolated at our institution were differentiated in two major groups of organisms clinically and epidemiologically related. Furthermore immunoblot typing showed same specific correlations with susceptibility patterns of ORSA isolates studied.

Synthesis of an hydrophilic, pK 8.05 buffer for isoelectric focusing in immobilized pH gradients

The synthesis of a new, pK 8.05 acrylamido weak base for isoelectric focusing in immobilized pH gradients (IPG) is here reported. This compound N,N-bis(2-hydroxyethyl)-N'-acryloyl-1,3-diaminopropane is strongly hydrophilic, and thus inhibits any potential hydrophobic interaction among proteins and the grafted basic groups in an IPG matrix. In addition, this novel buffer represents a step ahead towards the goal of closing the 'gap' between the commercially available Immobilines, pK 7.0 and 8.5. Owing to the large distance between these two neighboring pK values, it is difficult to arrange for linear narrow pH gradients in this region. IPG compositions obtained with this new buffer give highly linear pH gradients and protein profiles identical to those obtained with commercial Immobilines.

Effects of propolis flavonoids on virus infectivity and replication

The effect of five propolis flavonoids on the infectivity and replication of some herpesvirus, adenovirus, coronavirus and rotavirus strains has been studied. Experiments were performed in vitro in cell cultures using the viral plaque reduction technique. The cytotoxicity of flavonoids, including chrysine, kaempferol, acacetin, galangin and quercetin, was evaluated on uninfected monolayers to determine their effect on cell growth and viability. Chrysine and kaempferol caused a concentration-dependent reduction of intracellular replication of herpes-virus strains when monolayers were infected and subsequently cultured in a drug-containing medium. However, virus infectivity was not significantly affected. Acacetin and galangin had no effect on either the infectivity or replication of any of the viruses studied. Quercetin reduced infectivity and intracellular replication, but only at the highest concentrations tested.

Morphometric evaluation of CD16-positive cells with respect to CD2 antigen coexpression

We examined morphometric as well as functional characteristics of CD16-positive human peripheral blood lymphocytes on the basis of the coexpression of the CD2 antigen. For morphometric analyses, nuclear area and cellular area were determined by counting line cross-points of a superimposed quadratic lattice test system overlying nuclei and the whole cell, respectively. Moreover, to evaluate the cellular villousity degree, the maximum inscrible circle and an irregular polygon were inscribed within cell profiles. The cytoplasm fraction included between the plasmalemma and the traced irregular polygon was considered as the villous portion of the cell. Finally, the NK capability was measured in a 6-hr 51Cr-release assay with human K-562 myeloid cells as targets. Within the CD16-positive cell population, the CD16-positive/CD2-negative cells seem to represent the most efficient NK cell subset. To the higher NK capability correspond a higher villousity degree and a lower nuclear area/cellular area ratio of the CD2-negative/CD16-positive subset, when compared with CD2-positive/CD16-positive cells.

Emergence of cross-resistance to imipenem and other beta-lactam antibiotics in Pseudomonas aeruginosa during therapy

The emergence of resistance to imipenem and other beta-lactams by Pseudomonas aeruginosa was investigated with two pairs of isolates. Two of these isolates were susceptible to imipenem and other beta-lactam antibiotics, such as moxalactam, ceftriaxone and cefotaxime, while the other two had developed resistance to those antibiotics during imipenem therapy. So far imipenem-resistant isolates have not demonstrated cross-resistance to other beta-lactam agents. We examined in these clinical isolates the possible mechanisms of resistance due to permeability modifications, either in outer membrane proteins (porins) or to LPS (lipopolysaccharides) complex. Particularly we analysed possible modification of physico-chemical properties of outer membrane proteins, such as changes in their hydrophobicity and electrical charge. beta-lactamase production was also studied. Results showed that resistance to imipenem may be related to loss or modifications in hydrophobicity of an outer membrane protein of about 46 Kdal; other modifications concerned hydrophobicity of the porin OMP F and, in one strain, the LPS complex appears to be responsible for resistance to other beta-lactam antibiotics together in combination with the production of beta-lactamases.

Modification of norfloxacin inhibition of DNA gyrase induced by a 28 KDal DNA binding protein

We have previously studied a clinical isolate of Providencia stuartii which showed high levels of resistance to 4-quinolones, aminoglycoside and beta-lactam antibiotics (Landini et al., 1987). DNA gyrase from this isolate was inhibited for 50% of activity at a concentration of 15 microM of norfloxacin, which is about 5-fold higher compared to the 50% inhibitory concentration for a standard DNA gyrase. It has been described that 4-quinolone inhibition of DNA gyrase is caused by their binding to DNA and by the distortion induced in DNA tertiary structure, and that affinity binding of 4-quinolones is different for DNAs in different structures. In order to detect whether the interaction between pAT 153 and a protein able to modify DNA tertiary structure could affect norfloxacin inhibitory concentrations for DNA gyrase we purified from the clinical isolate of Providencia stuartii a DNA binding protein of about 28 KDal which induces changes in supercoiling degree of DNA. Assays of DNA gyrase activity were performed on the complex pAT 153-DNA binding protein-norfloxacin. Results showed an increase from 15 microM to 20 microM of 50% norfloxacin inhibitory concentration for DNA gyrase when pAT 153 was complexed with the 28 KDal protein.

Beta-lactam resistant Pseudomonas aeruginosa strains emerging during therapy: synergistic resistance mechanisms

The emergence of beta-lactam resistant strains of Pseudomonas aeruginosa during treatment was studied. Three different strains present before treatment persisted with changes in their beta-lactam resistance during treatment. The isolates before and after therapy were studied for beta-lactamase production and permeability barrier. The increased beta-lactam resistance was correlated with an increased permeability barrier. In order to verify if the permeability barrier was correlated with changes in outer membrane proteins, outer membrane preparations were analyzed by SDS-PAGE. Several differences were observed between the OMP profiles of the post therapy and the pre therapy isolates. Furthermore, an analysis of PBPs pattern of strains studied was carried out and alterations in target proteins were observed.

Modifications of DNA-gyrase and of permeability in a norfloxacin-resistant clinical isolate of Providencia stuartii

We obtained a clinical isolate of Providencia stuartii showing a high level of resistance to norfloxacin and to other 4-quinolones, whose target is the enzyme DNA-gyrase. This strain showed resistance also to beta-lactam and aminoglycoside antibiotics. In order to detect modification of DNA-gyrase, we performed supercoiling assays in vitro in presence of norfloxacin and ciprofloxacin. Furthermore, outer membrane proteins, which are involved in permeability mechanisms, were analyzed on SDS-polyacrylamide gels. Results showed that both modifications in DNA-gyrase and changes in outer membrane proteins can be held responsible for resistance to 4-quinolones; moreover, these modification are probably supported by a third mechanism of resistance.

Preliminary characterization of an inhibitory activity of fetal bovine serum on the infectivity of rotavirus strain SA-11

In the present work we studied non antibody inhibiting activity present in fetal bovine serum and active to Rotavirus infectivity and growth in cell cultures. This inhibitor was revealed by an in vitro neutralization test and characterized by gel filtration and chemical and enzymatic treatments. Furthermore, commercial preparations of bovine serum proteins were tested for inhibitory activity. Our results show that serum inhibition is partially resistant to trypsin and neuraminidase treatments but completely destroyed by KIO4. A similar activity was observed in a commercial serum bovine fraction containing predominantly alpha-globulins. These results seem to indicate that glycoproteins, and their glucidic components are the molecules predominantly involved in serum inhibition towards Rotavirus infectivity.

Occurrence of antipseudomonal beta-lactams and aminoglycosides resistance in Pseudomonas aeruginosa during therapy

Four strains of Pseudomonas aeruginosa clinical isolates were studied for resistance to antipseudomonal beta-lactams and aminoglycosides. Two of these strains were isolated from two different patients before antibiotic treatment, the other two strains, isolated during therapy, developed resistance to many of antipseudomonal beta-lactams and, in addition, to aminoglycoside antibiotics. All the strains produced a constitutive chromosomal beta-lactamase, while the latter two showed a significant reduction in permeability coefficient. Thus, a permeability change may be the major factor involved in the resistance to most antipseudomonal beta-lactams and may be responsible for development of cross-resistance to aminoglycosides.

Fluorescence polarization immunoassay to determine aminoglycoside modifying enzymes activity

The possible use of polarized-immunofluorescence to evaluate aminoglycoside-modifying enzyme activities has been investigated. The TDX instrument was used to determine the residual quantity of aminoglycoside following inactivation during the assay procedure. Through the spectrum of the modified aminoglycoside antibiotics the enzymes encoded on eleven R-factors from clinical isolates of Enterobacteriaceae have been identified.