Structural and magnetic properties of multi-core nanoparticles analysed using a generalised numerical inversion method.

The structural and magnetic properties of magnetic multi-core particles were determined by numerical inversion of small angle scattering and isothermal magnetisation data. The investigated particles consist of iron oxide nanoparticle cores (9 nm) embedded in poly(styrene) spheres (160 nm). A thorough physical characterisation of the particles included transmission electron microscopy, X-ray diffraction and asymmetrical flow field-flow fractionation. Their structure was ultimately disclosed by an indirect Fourier transform of static light scattering, small angle X-ray scattering and small angle neutron scattering data of the colloidal dispersion. The extracted pair distance distribution functions clearly indicated that the cores were mostly accumulated in the outer surface layers of the poly(styrene) spheres. To investigate the magnetic properties, the isothermal magnetisation curves of the multi-core particles (immobilised and dispersed in water) were analysed. The study stands out by applying the same numerical approach to extract the apparent moment distributions of the particles as for the indirect Fourier transform. It could be shown that the main peak of the apparent moment distributions correlated to the expected intrinsic moment distribution of the cores. Additional peaks were observed which signaled deviations of the isothermal magnetisation behavior from the non-interacting case, indicating weak dipolar interactions.

Synthesis methods to prepare single- and multi-core iron oxide nanoparticles for biomedical applications.

We review current synthetic routes to magnetic iron oxide nanoparticles for biomedical applications. We classify the different approaches used depending on their ability to generate magnetic particles that are either single-core (containing only one magnetic core, i.e. a single domain nanocrystal) or multi-core (containing several magnetic cores, i.e. single domain nanocrystals). The synthesis of single-core magnetic nanoparticles requires the use of surfactants during the particle generation, and careful control of the particle coating to prevent aggregation. Special attention has to be paid to avoid the presence of any toxic reagents after the synthesis if biomedical applications are intended. Several approaches exist to obtain multi-core particles based on the coating of particle aggregates; nevertheless, the production of multi-core particles with good control of the number of magnetic cores per particle, and of the degree of polydispersity of the core sizes, is still a difficult task. The control of the structure of the particles is of great relevance for biomedical applications as it has a major influence on the magnetic properties of the materials.

Helicobacter pylori: cultivability and antibiotic susceptibility of coccoid forms.

Helicobacter pylori is an actively dividing helical bacterium that changes to coccoid morphology as the culture ages. It has been suggested that the coccoid forms may be involved in transmission of infection and in relapses following antimicrobial therapy. The aim of this investigation was to determine the survival and susceptibility of the coccoid forms to amoxycillin, erythromycin, gentamicin and metronidazole. Colony counts and microscopic examination were performed after 1-4 weeks of culture. At 2 and 4 weeks, identical cultures were treated with the antibiotics for 24 h. Our results showed that 4-week cultures of coccoid forms were cultivable after antibiotic treatment.

Family adaptation to institutionalised mentally retarded patients. A preliminary report on an Italian population.

Family interactive patterns were investigated in the relatives of 20 mentally retarded patients institutionalised in two centres in Northern Italy. Expressed emotion (EE) was used as evaluation instrument. The results show a surprisingly high rate (45%) of high EE, even in relatives of patients who did not live inside the family. High EE was positively correlated to the presence of behavioral disorders in the patients, as already shown for children with conduct disorders. Treatment implications are discussed; there is an opportunity for the implementation of a family psychoeducational approach, aimed both at managing the behavioural consequences of the disorder and at enhancing rehabilitation programmes.

pH effects on the inhibition of extended-spectrum and classical TEM beta-lactamases by penicillanic acid sulphones.

MICs of piperacillin with tazobactam or sulbactam (4 mg/L) were higher at pH 6.5 than at pH 8.0 for Escherichia coli transconjugants with TEM-1 or TEM-2 enzymes, but not for those with TEM-3 or TEM-10 enzymes. Investigation showed: (i) all four enzymes were less sensitive to sulphones at pH 6.5 than at pH 8.0; (ii) pH effects on MICs arose also for the TEM-3 and TEM-10 producers at lower sulphone concentrations; (iii) the TEM-3 and TEM-10 producers formed less enzyme than those with TEM-1 and TEM-2 and (iv) pH effects on the MICs for TEM-1 producers depended on enzyme quantity. We conclude that all four TEM enzymes have pH-dependent susceptibility to sulphones, but whether this affects MICs depends on the inhibitor:enzyme ratio achieved in the bacteria.

Inhibitory and bactericidal activity of rokitamycin against Helicobacter pylori and morphological alterations.

Rokitamycin is a macrolide antibiotic, recently entered into clinical use. Its in vitro activity and kill kinetics against Helicobater pylori have been evaluated at 1 x the minimum inhibitory concentration (MIC), 2 x MIC and 4 x MIC at 2, 4, 8, 24 hours and compared with those of clarithromycin, erythromycin and amoxicillin. Morphological changes in H. pylori induced by rokitamycin incubation at these MICs and times were also investigated by scanning electron microscopy. All the antibiotics tested had good inhibitory activity against H. pylori, a slow growing microorganism. The order of MIC activity was clarithromycin > amoxicillin > rokitamycin > erythromycin. Rokitamycin killed more rapidly than the other antibiotics, in fact H. pylori strains were totally killed at 8 h (2 x MIC) and 4 h (4 x MIC) and after only 2 h incubation all concentrations greatly decreased the CFU/ml. These effects were also confirmed by the rapid appearance of surface and morphological alterations (focal blebs, constrictions, rounded forms) in the normal structure of H. pylori observed by scanning electron microscopy. Clinical studies should be conducted to investigate the in vivo activity of rokitamycin, as an agent to be used in the combination therapies against H. pylori.

'In vitro' development of metronidazole, erythromycin, amoxicillin and gentamicin resistance in Helicobacter pylori.

Serial passage of 37 Helicobacter pylori clinical isolates on increasing concentrations of metronidazole rapidly produced five strains with MICs up to 512 fold higher than those for the original strains. For these five metronidazole-resistant strains the MICs of erythromycin, gentamicin and amoxicillin were unchanged. When they were submitted to the same technique for these last antimicrobial agents, only one strain developed high level resistance to erythromycin and gentamicin having MIC values respectively up to 32 and 64-fold increased. Finally, no amoxicillin-resistant Helicobacter pylori could be obtained.

Activity of amoxicillin, metronidazole, bismuth salicylate and six aminoglycosides against Helicobacter pylori.

The in vitro activity of metronidazole, amoxicillin, bismuth salicylate and some aminoglycosides, such as ribostamycin, gentamicin, amikacin, tobramycin, streptomycin and netilmicin was evaluated against 60 clinical isolates of Helicobacter pylori using the agar dilution technique. All 60 strains were susceptible to amoxicillin, with minimum concentrations able to inhibit 50% (MIC 50) and 90% (MIC 90) of strains equal to 0.031 microgram/ml and 0.25 microgram/ml, respectively. Of the aminoglycosides, ribostamycin, streptomycin and amikacin had a little lower activity (MIC 50 of 2 micrograms/ml, MIC 90 of 4-8 micrograms/ml) than gentamicin, tobramycin and netilmicin, with MIC 50s of 0.125 microgram/ml and MIC 90s of 0.25 microgram/ml. Metronidazole was effective against the majority of the strains, but we found ten resistant strains. Finally, bismuth salicylate showed only slight antibacterial activity.

[Mental retardation and family environment: role of emotional factors]. / Ritardo mentale e ambiente familiare: ruolo dei fattori emotivi.

The authors present data from an experimental study conducted on 20 institutionalized mentally handicapped adult patients. Relevant family variables were investigated by means of the Expressed Emotion (EE) scales, then compared with similar variables obtained in a matched sample of 20 schizophrenic patients and their families. Results show, in relatives of mentally handicapped patients, a higher rate of Warmth than in relatives of schizophrenics (p = 0.009), while other EE scales appear to reach similar values in both groups. Within the mentally handicapped family group, a higher rate of Emotional Over-involvement (p = 0.046) is shown by relatives of patients treated with neuroleptic drugs. The presence of high Warmth and Emotional Over-involvement, together with low Criticism and Hostility, may be interpreted as adaptation by the families to an organic disease with very early onset, clearer ad less rejecting than schizophrenia.

PEPTY: a knowledge-based program for assisting medical reasoning in peptic diseases.

PEPTY is a program developed with the aim of providing a diagnostic and therapeutic assistance in managing peptic diseases. Its theoretical basis is an accurate analysis of current concepts in peptic disease diagnosis and treatment. This was done by reviewing recent literature and consulting skilled gastroenterologists. The decision tree includes three sections dealing with diagnostic, therapeutic and monitoring problems. The diagnostic section starts by evaluating clinical data from patient history and physical examination; the diagnostic hypotheses given at this level are refined and eventually confirmed by further information in the following section. Here the decision tree becomes modular in that a proper therapeutic and monitoring pathway is defined for four disease classes: gastroduodenal peptic ulcer and duodenitis, gastro-oesophageal reflux, erosive gastritis, and chronic antral gastritis. In the therapeutic section a cost-benefit analysis of possible therapeutic choices is always performed, but the final decision is made by the user. Complications, side effects and treatment efficacy are also considered and the program finally suggests the appropriate maintenance treatment. Patient data display, storage and retrieval, and explanation facilities are supplied. The system can provide a 'second opinion' in the medical practice and may be a useful learning tool for medical students.