In vitro production of panton-valentine leukocidin among strains of methicillin-resistant Staphylococcus aureus causing diverse infections.

BACKGROUND: Community-acquired methicillin-resistant Staphylococcus aureus strains have recently been associated with severe necrotizing infections. Greater than 75% of these strains carry the genes for Panton-Valentine leukocidin (PVL), suggesting that this toxin may mediate these severe infections. However, to date, studies have not provided evidence of toxin production. METHODS: Twenty-nine community-acquired methicillin-resistant Staphylococcus aureus and 2 community-acquired methicillin-susceptible S. aureus strains were collected from patients with infections of varying severity. Strains were analyzed for the presence of lukF-PV and SCCmecA type. PVL production in lukF-PV gene-positive strains was measured by ELISA, and the amount produced was analyzed relative to severity of infection. RESULTS: Only 2 of the 31 strains tested, 1 methicillin-resistant Staphylococcus aureus abscess isolate and 1 nasal carriage methicillin-susceptible S. aureus isolate, were lukF-PV negative. All methicillin-resistant Staphylococcus aureus strains were SCCmec type IV. PVL was produced by all strains harboring lukF-PV, although a marked strain-to-strain variation was observed. Twenty-six (90%) of 29 strains produced 50-350 ng/mL of PVL; the remaining strains produced PVL in excess of 500 ng/mL. The quantity of PVL produced in vitro did not correlate with severity of infection. CONCLUSIONS: Although PVL likely plays an important role in the pathogenesis of these infections, its mere presence is not solely responsible for the increased severity. Factors that up-regulate toxin synthesis in vivo could contribute to more-severe disease and worse outcomes in patients with community-acquired methicillin-resistant Staphylococcus aureus infection.     

Mutations of the Imprinted CDKN1C Gene as a Cause of the Overgrowth Beckwith–Wiedemann Syndrome: Clinical Spectrum and Functional Characterization

Beckwith–Wiedemann syndrome (BWS) is an imprinting disorder associating macroglossia, abdominal wall defects, visceromegaly, and a high risk of childhood tumor. Molecular anomalies are mostly epigenetic; however, mutations of CDKN1C are implicated in 8% of cases, including both sporadic and familial forms. We aimed to describe the phenotype of BWS patients with CDKN1C mutations and develop a functional test for CDKN1C mutations. For each propositus, we sequenced the three exons and intron–exon boundaries of CDKN1C in patients presenting a BWS phenotype, including abdominal wall defects, without 11p15 methylation defects. We developed a functional test based on flow cytometry. We identified 37 mutations in 38 pedigrees (50 patients and seven fetuses). Analysis of parental samples when available showed that all mutations tested but one was inherited from the mother. The four missense mutations led to a less severe phenotype (lower frequency of exomphalos) than the other 33 mutations. The following four tumors occurred: one neuroblastoma, one ganglioneuroblastoma, one melanoma, and one acute lymphoid leukemia. Cases of BWS caused by CDKN1C mutations are not rare. CDKN1C sequencing should be performed for BWS patients presenting with abdominal wall defects or cleft palate without 11p15 methylation defects or body asymmetry, or in familial cases of BWS.     

Utility of clinical comprehensive genomic characterization for diagnostic categorization in patients presenting with hypocellular bone marrow failure syndromes

Bone marrow failure (BMF) related to hypoplasia of hematopoietic elements in the bone marrow is a heterogeneous clinical entity with a broad differential diagnosis including both inherited and acquired causes. Accurate diagnostic categorization is critical to optimal patient care and detection of genomic variants in these patients may provide this important diagnostic and prognostic information. We performed real-time, accredited (ISO15189) comprehensive genomic characterization including targeted sequencing and whole exome sequencing in 115 patients with BMF syndromes (median age 24 years, range: 3 months - 81 years). In patients with clinical diagnoses of inherited BMF syndromes, acquired BMF syndromes or clinically unclassifiable BMF we detected variants in 52% (12 of 23), 53% (25 of 47) and 56% (25 of 45) respectively. Genomic characterization resulted in a change of diagnosis in 30 of 115 (26%) including the identification of germline causes for 3 of 47 and 16 of 45 cases with pre-test diagnoses of acquired and clinically unclassifiable BMF respectively. The observed clinical impact of accurate diagnostic categorization included choice to perform allogeneic stem cell transplantation, disease-specific targeted treatments, identification of at-risk family members and influence of sibling allogeneic stem cell donor choice. Multiple novel pathogenic variants and copy number changes were identified in our cohort including in TERT, FANCA, RPS7 and SAMD9. Whole exome sequence analysis facilitated the identification of variants in two genes not typically associated with a primary clinical manifestation of BMF but also demonstrated reduced sensitivity for detecting low level acquired variants. In conclusion, genomic characterization can improve diagnostic categorization of patients presenting with hypoplastic BMF syndromes and should be routinely performed in this group of patients.     

Novel Ranking System for Identifying Efficacious Anti-Influenza Virus PB2 Inhibitors

Through antigenic drift and shifts, influenza virus infections continue to be an annual cause of morbidity in healthy populations and of death among elderly and at-risk patients. The emergence of highly pathogenic avian influenza viruses such as H5N1 and H7N9 and the rapid spread of the swine-origin H1N1 influenza virus in 2009 demonstrate the continued need for effective therapeutic agents for influenza. While several neuraminidase inhibitors have been developed for the treatment of influenza virus infections, these have shown a limited window for treatment initiation, and resistant variants have been noted in the population. In addition, an older class of antiviral drugs for influenza, the adamantanes, are no longer recommended for treatment due to widespread resistance. There remains a need for new influenza therapeutic agents with improved efficacy as well as an expanded window for the initiation of treatment. Azaindole compounds targeting the influenza A virus PB2 protein and demonstrating excellent in vitro and in vivo properties have been identified. To evaluate the in vivo efficacy of these PB2 inhibitors, we utilized a mouse influenza A virus infection model. In addition to traditional endpoints, i.e., death, morbidity, and body weight loss, we measured lung function using whole-body plethysmography, and we used these data to develop a composite efficacy score that takes compound exposure into account. This model allowed the rapid identification and ranking of molecules relative to each other and to oseltamivir. The ability to identify compounds with enhanced preclinical properties provides an opportunity to develop more-effective treatments for influenza in patients.     

Post-ablation prolongation of atrioventricular nodal refractory period is correlated with long-term success of cryoablation for atrioventricular nodal reentrant tachycardia in the case of the persistence of a residual jump

Purpose

A residual slow pathway after successful cryoablation for atrioventricular nodal reentrant tachycardia (AVNRT) is correlated with a higher recurrence rate. We described determinants of recurrence in subjects with a residual jump.

Methods

We analyzed the data of subjects with acute successful slow pathway cryoablation for AVNRT using a 6-mm-tip cryocatheter. Success was defined as AVNRT non-inducibility. Patients with no baseline elicitable jump, no inducible AVNRT, and transient first atrioventricular (AV) block at the last site were excluded.

Results

From 371 patients who underwent cryoablation from May 2002 to March 2011, 303 fulfilled the entry criteria (mean age, 41?±?16; 222 women). Baseline AV nodal effective refractory period (ERP) was 272?±?57?ms, postprocedural 331?±?64 (P?P?=?0.01). In patients with a jump, only ?? AV nodal ERP was correlated with recurrence (37?±?41 vs. 68?±?47?ms; P?30?ms (P?Conclusions Suppression of slow pathway conduction is the optimal endpoint for AVNRT cryoablation. A residual jump can be tolerated if AV nodal ERP postcryoablation is prolonged >30?ms.     

Validation of cephalic index measurements in scaphocephaly

Introduction

The cephalic index (CI) of the head can be measured manually using a caliper, the original technique, but it is also possible to determine it using skull X-ray, 2DCT and 3DCT images, 3D photo and with help of plagiocephalometry (PCM).

Patients and methods

In this study, the manual caliper determination is statistically compared with other measuring methods for scaphocephaly patients (n?=?39).

Results

The CI mean differences for the most representative data are sequentially 3.74, 2.16, 1.09 and 0.97 for the 2DCT, PCM, 3D photo and 3DCT techniques. The CI 2DCT values show a significant difference (p?<?0.01) in reference to CI manually, while the other techniques show a p?>?0.05.

Conclusion

The conclusions are that significantly different results are achieved when using 2DCT relative to the manual caliper determination. No significant difference is observed between the 3D techniques and the manual method.     

Soluble MHC Class I chain-related molecule serum levels are predictive markers of implantation failure and successful term pregnancies following IVF

BACKGROUND: Despite ongoing progresses of IVF techniques, biomarkers predicting their outcome prior to IVF initiation are lacking. We investigated whether serum levels of the stress-inducible soluble major histocompatibility complex Class I chain-related molecule, MICA, (sMIC), a regulator of cellular immunity, can be predictive of implantation or pregnancy failure after IVF. METHODS: sMIC serum levels, evaluated during the follicular phase of the cycle preceding in vitro fertilization, in a cohort of 170 infertile women with 22.3% IVF success rate were analyzed in association with implantation/pregnancy failure or live birth outcomes after IVF. RESULTS: sMIC serum levels, detected in 38% of all women undergoing IVF, were shown to be predictive both of implantation failure (> or = 2.45 ng/ml cut off, odds ratio (OR) = 4.6; 95% confidence interval (CI) = 1.08 - 19.79; P = 0.031) and successful pregnancy (< 2.45 ng/ml, OR = 13.8; 95% CI = 2.03-118.3; P = 0.002). When successful implantation occurred, sMIC levels > 3.2 ng/ml were predictive of spontaneous abortion (OR = 35; 95% CI = 1.74-703; P = 0.026). CONCLUSIONS: sMIC is thus to be considered as a novel blood biomarker which, when quantified prior to initiation of IVF, anticipates chances for infertile women to give birth to a viable baby. Considering medical and psychological cost of IVF, this non-invasive assay may thus contribute to better counseling, treatment and care of infertile couples prior to IVF.