265 research outputs found
Microwave surface resistance of pristine and neutron-irradiated MgB2 samples in magnetic field
We report on the microwave surface resistance of two polycrystalline Mg11B2
samples; one consists of pristine material, the other has been irradiated at
very high neutron fluence. It has already been reported that in the strongly
irradiated sample the two gaps merge into a single value. The mw surface
resistance has been measured in the linear regime as a function of the
temperature and the DC magnetic field, at increasing and decreasing fields. The
results obtained in the strongly irradiated sample are quite well justified in
the framework of a generalized Coffey and Clem model, in which we take into
account the field distribution inside the sample due to the critical state. The
results obtained in the pristine sample show several anomalies, especially at
low temperatures, which cannot be justified in the framework of standard models
for the fluxon dynamics. Only at temperatures near Tc and for magnetic fields
greater than 0.5Hc2(T) the experimental data can quantitatively be accounted
for by the Coffey and Clem model, provided that the upper-critical-field
anisotropy is taken into due account.Comment: RevTeX, 13 pages with 10 eps figures, in press on EPJ
Staphylococcal cassette chromosome mec typing and meca sequencing in methicillin-resistant staphylococci from Algeria: A highly diversified element with new mutations in mecA
Genetic mechanisms of methicillin resistance are still relevant in staphylococci. The aims of this study are to assess the possible exchanges of staphylococcal cassette chromosome mec (SCCmec) among isolates of methicillin-resistant staphylococci (MRS) and to check for known or new mutations in mecA DNA. A total of 35 MRS non-repetitive isolates were recovered, including 20 Staphylococcus haemolyticus, 7 Staphylococcus aureus, 4 Staphylococcus sciuri, 2 Staphylococcus saprophyticus and 1 isolate each of Staphylococcus xylosus and Staphylococcus lentus. Only 16 of the 35 strains were assigned to known SCCmec types: 7 SCCmec VII, 6 SCCmec IV and 3 SCCmec III, with possible horizontal transfer of the SCCmec VII from methicillin-resistant S. haemolyticus to methicillin-susceptible S. aureus. mecA gene sequencing in ten selected isolates allowed description of nine punctual mutations, seven of which were reported for the first time. The most frequent mutation was G246E, identified in isolates of methicillin-resistant S. aureus, S. sciuri, S. saprophyticus and S. lentus. These results emphasized the high degree of genetic diversity of SCCmec element in MRS and describe new missense mutations in mecA, which might be important in understanding the evolution of methicillin and new b-lactam resistance
Dynamics and molecular evolution of HIV-1 strains in Sicily among antiretroviral na\uefve patients.
HIV-1 subtype B is the most frequent strain in Sicily. To date, there is no available data about the genetic diversity of HIV-1 viral strains circulating in Sicily among antiretroviral (ARV) na\uefve subjects and the role of immigration as potential determinant of evolutionary dynamics of HIV-1 molecular epidemiology.
For this purpose, HIV-1 polymerase (pol) sequences obtained from 155 ARV na\uefve individuals from 2004 to 2009 were phylogenetically analysed.
The overall rate of HIV-1 non-B infections was 31.0% (n = 48/155), increasing from 7.8% in 2004\u20132006 to 40.9% in 2009, and about one-third were identified as unique recombinant forms.
CRF02_AG was the prevalent non-B clade (n = 28/48, 58.3%), while subtype C-related strains were responsible for about 30% HIV-1 infections.
Non-B viruses strictly associated with heterosexual transmission (85.4%) and were mostly found among immigrants (77.1%). Phylogenetic analysis of non-B sequences found in foreign-born subjects was geographically correlated to the respective country of origin. Moreover, the detection of non-B viral variants in the autochthonous population may support an increasing genetic diversity in Sicily as well as a local circulation of HIV strains also uncommon in our country.
In Sicily, HIV-1 epidemic is still mostly attributable to the B subtype. Nevertheless, migration and population movements are progressively introducing novel HIV-1 subtypes causing a continuous increase of HIV-1 molecular dynamic at local level. Molecular surveillance is needed to monitor the genetic evolution of HIV-1 epidemic
Enhanced surveillance of invasive listeriosis in the Lombardy region, Italy, in the years 2006-2010 reveals major clones and an increase in serotype 1/2a.
Background
Invasive listeriosis is a rare, life-threatening foodborne disease. Lombardy, an Italian region accounting for 16% of the total population, reported 55% of all listeriosis cases in the years 2006-2010. The aim of our study was to provide a snapshot of listeriosis epidemiology in this region after the implementation of a voluntary laboratory-based surveillance system.
Methods
We characterized by serotyping, pulsed-field gel electrophoresis, multilocus sequence typing and detection of epidemic clone markers, 134 isolates from 132 listeriosis cases, including 15 pregnancy-related cases, occurring in the years 2006-2010 in Lombardy. Demographic and clinical characteristics of cases have also been described.
Results
The mean age of non pregnancy-associated cases was 64.7\u2009years, with 55.9% of cases being older than 65\u2009years. Cases having no underlying medical conditions accounted for 11.6%. The all-cause fatality rate of 83 cases with a known survival outcome was 25.3%.
Serotypes 1/2a and 4b comprised 52.2% and 38.8% of isolates, respectively. Seventy-three AscI pulsotypes and 25 sequence types assigned to 23 clonal complexes were recognized. Moreover, 53 (39.5%) isolates tested positive for the epidemic clone markers. Twelve molecular subtype clusters including at least three isolates were detected, with cluster 11 (1/2a/ST38) including 31 isolates identified during the entire study period. No outbreaks were notified to public health authorities during this period.
Conclusions
The findings of our study proved that epidemiology of listeriosis in Lombardy is characterized by a high prevalence of major clones and the increasing role of serotype 1/2a. Molecular subtyping is an essential tool in the epidemiology and surveillance of listeriosis. Rapid molecular cluster detection could alert about putative outbreaks, thus increasing the chance of detecting and inactivating routes of transmission
OXA-163-producing Klebsiella pneumoniae in Cairo, Egypt, in 2009 and 2010.
Two genetically unrelated OXA-163-carrying Klebsiella pneumoniae strains were identified from two infection cases in June 2009 and May 2010 in Cairo, Egypt. OXA-163-producing Enterobacteriaceae had been previously reported in Argentina only. Both patients had no history of travel abroad. The emergence of this newly recognized OXA-48-related \u3b2-lactamase able to hydrolyze cephalosporins and carbapenems is especially worrying in a geographic area where OXA-48 is endemic and effective surveillance for antibiotic resistance is largely unaffordable
Descriptive Epidemiology of Nasal Carriage of Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus Among Patients Admitted to Two Healthcare Facilities in Algeria
Aim: To evaluate nasal carriage rate and variables associated with Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) in patients admitted in two healthcare facilities. Results: S. aureus was isolated from 159 (26%) of the enrolled patients. Methicillin-susceptible S. aureus was isolated from 150 (24.5%) patients, and MRSA was isolated from 9 (1.5%). Cancer and previous hospitalization were associated with a significantly higher frequency of nasal S. aureus carriage among the patients admitted to the general hospital and the nephrology department, respectively. MRSA isolates were heterogeneous with respect to their staphylococcal cassette chromosome mec element (SCCmec) type, sequence type (ST), and toxin genes (pvl and tst1) content. Four isolates were attributed with the ST80-MRSA-IV clone, which is known to be predominant in Algeria. Conclusions: This is the first assessment of S. aureus and MRSA nasal carriage and associated variables in Algeria. Our findings provide also a picture of the MRSA strains circulating in the community in this geographic area. They can be useful as a guide for implementing screening and control procedures against S. aureus/MRSA in the Algerian healthcare facilities
Fine characterization of immunological mechanisms mediated by the major allergens of Parietaria judaica and hypoallergenic hybrid, rPjEDcys
Purpose: Allergy is a hypersensitivity disease IgE-mediated, affecting more than 25% of the population. The
symptoms of IgE-mediated allergies reactions can be transiently ameliorated pharmacologically, but the only
curative treatment of allergies is Allergen-Specific Immunotherapy (SIT). Recombinant hypoallergenic
allergen derivatives with reduced allergenic activity have been engineered to reduce side effects during SIT.
Parietaria judaica (Pj) pollen contains two major allergens belonging to the family of Lipid Tranfer Proteins
(Par j 1 and Par j 2). By means of DNA recombinant technology, a hybrid hypoallergenic (PjEDcys),
expressing disulphide bond variants of Par j 1 and Par j 2, was generated. The aim of this research project is
to study the immunological mechanisms activated by the major allergens of Parietaria judaica, Par j 1 and
Par j 2, and hypoallergenic hybrid rPjEDcys. Moreover, the project I am involved is trying to address the
question whether this engineered hypoallergenic derivative can be a potential products for safer Allergen
Specific Immunotherapy (SIT).
Methods: Par j 1, Par j 2 and PjEDcys were produced as recombinant proteins. Human Peripheral Blood
Mononuclear Cell (PBMC) from P. judaica allergic patients were stimulated in vitro with wild-type
recombinant allergens and hybrid. PBMC proliferation assay, cytokine secretion assay, magnetic cell sorting
of different subset of regulatory T cells, multiparametric flow cytometric analysis and molecular
characterization using Real Time-PCR on sorted cells allow to study the biological properties of wild-type
recombinant allergens and hybrid hypoallergenic derivate.
Results: In vitro analysis suggested that PjEDcys have a reduced allergenity and maintained T cells
reactivity. PBMC of P. judaica allergic patients stimulated in vitro with the hybrid and the wild-type
recombinant allergens scored a percentage of proliferating CD4+ and CD56+ cell higher than unstimulated
sample. Consistent with these data, cytokine secretion assay on CD4+ cells demonstrated that PBMC
stimulation with rPjEDcys showed a percentage of IL-5 and IL-13 secreting T CD4+ cells lower than the
wild-type allergens. Both rPjEDcys and wild-type stimulation promote the secretion of IFN- \u3b3 and IL-10 by
T CD4+ cells. Finally whit the aim to study which subset of regulatory cells respond to wild-tipe allergens
and hypoallergenic hybrid new experiment are setting.
Discussion: In this experimental setting, the use of the major allergens of Pj and the hybrid polypeptides,
rPjEDcys allows me to study the immunological mechanisms activated by the two different antigen
stimulation and to investigate differences between the wild-type allergen and the hypoallergenic mutant
rPjEDcys. Our data showed that CD4+ cells are clearly the predominant cell population proliferating in
response to mixture of Par j 1 and Par j 2 allergens. The hypoallergenic derivate rPjEDcys retain the ability
to stimulate CD4+ cells proliferation like the mixture of allergens (rPar j 1 and rPar j 2). Moreover these
results highlighted a particular interesting datum; the mixture of allergens and the rPjEDcys hybrid showed
the ability to stimulate an innate immune response, inducing CD56+ cells proliferative response. Cytokine
secretion assay demonstrate that rPjEDcys reduce the secretion of IL-5 and IL-13, Th2 cytokines with a
critical role in the development of allergy, compared to wild-type allergens. This may reflect the different
biological function exerted by rPjEDcys.
Conclusion: Collectivelly, our findings demonstrate that PjEDcys show a reduced allergenicity but
maintained its immunogenicity and maybe it is also capable to regulate and redirect the immune response.
These results suggest that PjEDcys represent a useful approach for immunotherapy of allergic disease
A severe case of Israeli spotted fever with pleural effusion in Italy
Background: The most common Italian rickettsiosis is Mediterranean Spotted Fever (MSF). MSF is commonly associated with a symptom triad consisting of fever, cutaneous rash, and inoculation eschar. The rash is usually maculopapular but, especially in severe presentations, may be petechial. Other typical findings are arthromyalgia and headache. Herein, we describe for the first time an unusual case of Israeli spotted fever (ISF) associated with interstitial pneumonia and pleural effusion in which R. conorii subsp. israelensis was identified by molecular methods in the blood, as well as in the pleural fluid. Case presentation: A 72-year-old male presented with a 10-day history of remittent fever. On admission, the patient’s general condition appeared poor with confusion and drowsiness; the first assessment revealed a temperature of 38.7°, blood pressure of 110/70 mmHg, a blood oxygen saturation level of 80% with rapid, frequent, and superficial breathing using accessory muscles (28 breaths per minute), and an arrhythmia with a heart rate of 90 beats per minute. qSOFA score was 3/3. Chest CT revealed ground-glass pneumonia with massive pleural effusion. Petechial exanthema was present diffusely, including on the palms and soles, and a very little eschar surrounded by a violaceous halo was noted on the dorsum of the right foot. Awaiting the results of blood cultures, broad-spectrum antibiotic therapy with meropenem 1 g q8h, ciprofloxacin 400 mg q12h, and doxycycline 100 mg q12h was initiated. Doxycycline was included in the therapy because of the presence of petechial rash and fever, making us consider a diagnosis of rickettsiosis. This suspicion was confirmed by the positivity of polymerase chain reaction on whole blood for R. conorii subsp. israelensis. Thoracentesis was performed to improve alveolar ventilation. R. conorii subsp. israelensis was again identified in the pleural fluid by PCR technique. On day 4 the clinical condition worsened. Blood exams showed values suggestive of secondary hemophagocytic lymphohistiocytosis; 4 out of 8 diagnostic criteria were present and empirical treatment with prednisone was started resulting in a gradual improvement in general condition. Conclusions: Israeli spotted fever may be a severe disease. A high index of suspicion is required to promptly start life-saving therapy. Pleural effusion and interstitial pneumonia may be part of the clinical picture of severe rickettsial disease and should not lead the physician away from this diagnosis
Successful control of an outbreak of colonization by Klebsiella pneumoniae carbapenemase-producing K.\ua0pneumoniae sequence type 258 in a neonatal intensive care unit, Italy
This article reports an outbreak of colonization by Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp) sequence type (ST) 258 in a neonatal intensive care unit (NICU) in Palermo, Italy. KPC-Kp ST258 was detected by an active surveillance culture programme. Between 18th September and 14th November 2012, KPC-Kp was isolated from 10 out of 54 neonates admitted in the outbreak period. No cases of infection were recorded. Male sex was associated with colonization, whereas administration of ampicilline-sulbactam plus gentamicin was protective. Infection control interventions interrupted the spread of KPC-Kp without the need to close the NICU to new admissions. (C) 2013 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved
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