Selective, novel spleen tyrosine kinase (Syk) inhibitors suppress chronic lymphocytic leukemia B-cell activation and migration

Syk is a protein tyrosine kinase that couples B-cell receptor (BCR) activation with downstream signaling pathways, affecting cell survival and proliferation. Moreover, Syk is involved in BCR-independent functions, such as B-cell migration and adhesion. In chronic lymphocytic leukemia (CLL), Syk becomes activated by external signals from the tissue microenvironment, and was targeted in a first clinical trial with R788 (fostamatinib), a relatively nonspecific Syk inhibitor. Here, we characterize the activity of two novel, highly selective Syk inhibitors, PRT318 and P505-15, in assays that model CLL interactions with the microenvironment. PRT318 and P505-15 effectively antagonize CLL cell survival after BCR triggering and in nurse-like cell-co-cultures. Moreover, they inhibit BCR-dependent secretion of the chemokines CCL3 and CCL4 by CLL cells, and leukemia cell migration toward the tissue homing chemokines CXCL12, CXCL13, and beneath stromal cells. PRT318 and P505-15 furthermore inhibit Syk and extracellular signal-regulated kinase phosphorylation after BCR triggering. These findings demonstrate that the selective Syk inhibitors PRT318 and P505-15 are highly effective for inhibition of CLL survival and tissue homing circuits, and support the therapeutic development of these agents in patients with CLL, other B-cell malignancies and autoimmune disorders.

The stability of markers in dried-blood spots for recommended newborn screening disorders in the United States

OBJECTIVE

We aimed to measure separately the contributions of heat and humidity to changes in levels of 34 markers of inborn disorders in dried-blood-spot (DBS) samples.

DESIGN AND METHODS

We stored paired sets of DBSs at 37°C for predetermined intervals in low-humidity and high-humidity environments. Marker levels of all samples in each complete sample set were measured in a single analytic run.

RESULTS

During the 30 ± 5 day studies, galactose-1-phosphate uridyltransferase and biotinidase lost almost 65% of initial activities in low-humidity storage; most of the degradation in 27 other markers was attributable to adverse effects of high-humidity storage; seven markers in DBSs stored at high humidity lost more than 90% of initial levels by the end of the study and 4 of the 7 lost more than 50% of initial levels within the first week of storage.

CONCLUSIONS

Minimizing both humidity and temperature in DBS transportation and storage environments is essential to maintaining sample integrity.

Streptococcus pneumoniae endocarditis on replacement aortic valve with panopthalmitis and pseudoabscess

A 63-year-old woman with a previous episode of Streptococcus agalactiae endocarditis requiring a bioprosthetic aortic valve replacement presented with a short history of malaise, a right panopthalmitis with a Roth spot on funduscopy of the left eye and Streptococcus pneumoniae grown from vitreous and aqueous taps as well as blood cultures. She developed first degree heart block and her ECG was suggestive of an aortic root abscess. This gradually resolved over 6 weeks, during which she was treated with intravenous antibiotics. After careful consideration, it is likely that what was thought to be an aortic root abscess was instead an area of perivalvular inflammation.

KIR2DS1 genotype predicts for complete cytogenetic response and survival in newly diagnosed chronic myeloid leukemia patients treated with imatinib

Natural killer (NK) cells are expanded in chronic myeloid leukemia (CML) patients on tyrosine kinase inhibitors (TKI) and exert cytotoxicity. The inherited repertoire of killer immunoglobulin-like receptors (KIR) may influence response to TKI. We investigated the impact of KIR-genotype on outcome in 166 chronic phase CML patients on first-line imatinib treatment. We validated our findings in an independent patient group. On multivariate analysis, KIR2DS1 genotype (RR=1.51, P=0.03) and Sokal risk score (low-risk RR=1, intermediate-risk RR=1.53, P=0.04, high-risk RR=1.69, P=0.034) were the only independent predictors for failure to achieve complete cytogenetic response (CCyR). Furthermore, KIR2DS1 was the only factor predicting shorter progression-free (PFS) (RR=3.1, P=0.03) and overall survival (OS) (RR=2.6, P=0.04). The association between KIR2DS1 and CCyR, PFS and OS was validated by KIR genotyping in 174 CML patients on first-line imatinib in the UK multi-center SPIRIT-1 trial; in this cohort, KIR2DS1(+) patients had significantly lower 2-year probabilities of achieving CCyR (76.9 vs 87.9%, P=0.003), PFS (85.3 vs 98.1%, P=0.007) and OS (94.4 vs 100%, P=0.015) than KIR2DS1(-) patients. The impact of KIR2DS1 on CCyR was greatest when the ligand for the corresponding inhibitory receptor, KIR2DL1, was absent (P=0.00006). Our data suggest a novel role for KIR-HLA immunogenetics in CML patients on TKI.

Design of waveguide-integrated semiconductor laser sources for optical frequency comb generation

A numerical study of threshold gain and modal dispersion in integrated semiconductor laser optical frequency comb sources is presented. We consider an example device where one of the cleaved facets of the laser is replaced by a short Bragg grating section and show that as many as 16 modes can be selected at the first harmonic of the underlying Fabry-Perot cavity. An intracavity approach to limiting the grating-induced dispersion that can be implemented directly through the grating profile is demonstrated.

Undergraduate medical education in substance use in Ireland: a review of the literature and discussion paper

BACKGROUND

Medical complications of substance use are a considerable cause of morbidity and the role of the physician in the care of such problems has consistently been demonstrated. Appropriate knowledge and skills are necessary to carry out this role.

AIMS

To review the literature on training undergraduate medical students in identifying and managing substance misuse and to discuss the implications of this literature for Irish medical education.

METHODS

A search of the literature was performed using keywords; "substance-related disorders", "undergraduate" and "curriculum". All abstracts were reviewed and the full text of relevant abstracts was studied and references reviewed for further articles.

RESULTS

Despite an increase in prevalence of the problem of drug and alcohol use in Ireland and the UK, this has not been reflected in undergraduate medical curricula. In the UK, minimal time is devoted to formal teaching of medical undergraduates in the area of substance misuse and many doctors do not have the appropriate knowledge, skills, attitudes and confidence to treat patients with such problems. In Ireland, no data has reported formal undergraduate teaching hours in the area of drug and alcohol misuse. Internationally, substance abuse curricula have been developed and implemented in medical schools in the United States and Australia.

CONCLUSION

While substance misuse is increasing in prevalence, this is not reflected in the composition of medical curricula, especially in Ireland. International best practice whereby undergraduate curricula that adequately address substance misuse and related issues are systematically developed and implemented, is recommended for adoption by Irish medical schools.

Calcium mediates glomerular filtration through calcineurin and mTORC2/Akt signaling

Alterations to the structure of the glomerular filtration barrier lead to effacement of podocyte foot processes, leakage of albumin, and the development of proteinuria. To better understand the signaling pathways involved in the response of the glomerular filtration barrier to injury, we studied freshly isolated rat glomeruli, which allows for the monitoring and pharmacologic manipulation of early signaling events. Administration of protamine sulfate rapidly damaged the isolated glomeruli, resulting in foot process effacement and albumin leakage. Inhibition of calcium channels and chelation of extracellular calcium reduced protamine sulfate-induced damage, suggesting that calcium signaling plays a critical role in the initial stages of glomerular injury. Calcineurin inhibitors (FK506 and cyclosporine A) and the cathepsin L inhibitor E64 all inhibited protamine sulfate-mediated barrier changes, which suggests that calcium signaling acts, in part, through calcineurin- and cathepsin L-dependent cleavage of synaptopodin, a regulator of actin dynamics. The mTOR inhibitor rapamycin also protected glomeruli, demonstrating that calcium signaling has additional calcineurin-independent components. Furthermore, activation of Akt through mTOR had a direct role on glomerular barrier integrity, and activation of calcium channels mediated this process, likely independent of phosphoinositide 3-kinase. Taken together, these results demonstrate the importance of calcium and related signaling pathways in the structure and function of the glomerular filtration barrier.

Timing characterization of 100 GHz passively mode-locked discrete mode laser diodes

We report on the characterization of the timing stability of passively mode-locked discrete mode diode laser sources. These are edge-emitting devices with a spatially varying refractive index profile for spectral filtering. Two devices with a mode-locking frequency of 100 GHz are characterized. The first device is designed to support a comb of six modes and generates near Fourier limited 1.9 ps pulses. The second supports four primary modes resulting in a sinusoidal modulation of the optical intensity. Using a cross-correlation technique, we measured a 20 fs pulse to pulse timing jitter for the first device, while, for the second device, a mode-beating (RF) linewidth of 1 MHz was measured using heterodyne mixing in a semiconductor optical amplifier. Comparison of these results with those obtained for an equivalent Fabry-Perot laser indicates that the spectral filtering mechanism employed does not adversely affect the timing properties of these passively mode-locked devices.

Patent ductus arteriosus hemodynamics in very premature infants treated with poractant alfa or beractant for respiratory distress syndrome

OBJECTIVE

Respiratory distress syndrome (RDS), requiring mechanical ventilation and exogenous surfactant treatment, and patent ductus arteriosus (PDA), are common co-morbidities in very premature infants. The effects of intra-tracheal surfactant administration on the cardiovascular and pulmonary systems in very premature infants with RDS and PDAs are not well characterized. We evaluated the effects of poractant alfa and beractant, surfactants with different rapidity of onset and duration of action, in very premature infants with RDS. To assess whether there were differences in PDA hemodynamics in very premature infants with RDS treated with poractant alfa and beractant during the first week of life and to assess whether poractant alfa or beractant had a direct effect on PDAs and PDA hemodynamics following the second dose of surfactant.

STUDY DESIGN

We studied 50 in-born, very premature infants with RDS, 24 0 of 7 to 29 6 of 7 weeks gestation, treated with poractant alfa or beractant, in an open label, 1:1, randomized clinical trial. A subgroup of 16 patients with severe RDS, treated with a second dose of surfactant, had echocardiographical assessments before and 20 to 30 min after the second dose of surfactant.

RESULT

There were 25 infants treated with poractant alfa (27.1±1.6 weeks, birth weight 930±231 g) and 25 treated with beractant (26.7±1.7 weeks, P=0.407 and birth weight 898±282 g, P=0.666). Clinically significant PDAs were diagnosed and treated in 8 of 25 (32%) of the poractant alfa and 19 of 25 (76%) of the beractant group (P=0.002). Indomethacin treatment was slightly earlier (3.4±2.5 days) in the poractant alfa than in the beractant group (5.1±4.9 days, P=0.038). Right ventricle pressure (RVP)/systolic arterial pressure (SAP) ratio in the first week was slightly lower in the poractant alfa (64±20%) than in the beractant (78±26%, P=0.048) group. Following a second dose of surfactant, neither poractant alfa nor beractant changed PDA flow. These hemodynamic observations were associated with less respiratory support in the poractant alfa group, allowing earlier extubation (13 of 25 at 48 h and 15 of 25 at 72 h), than in the beractant group (6 of 25 at 48 h, P=0.044, and 8 of 25 at 72 h, P=0.049).

CONCLUSION

The more rapid improvement in pulmonary function in the poractant alfa-treated infants was associated with a lower RVP/SAP ratio and a corresponding earlier treatment with indomethacin. Neither surfactant had a significant direct effect on PDA hemodynamics. The lower frequency of clinically significant PDAs in the poractant alfa compared with the beractant group may represent an indirect effect of the differences in the pulmonary improvement induced by the two surfactants.

Excitation profile of surface-enhanced Raman scattering in graphene-metal nanoparticle based derivatives

Understanding energy transfer mechanisms in graphene derivatives is strongly motivated by the unusually interesting electronic properties of graphene, which can provide a template for the creation of novel nanostructured derivatives. From a synthetic point of view, it is highly attractive to envision being able to synthesize pristine graphene from precursors such as graphene oxide (GO). While this goal may be challenging over large length-scales, it is possible to generate regions of graphene at the nanoscale, confirmed by Raman spectroscopy or other methods. We describe an in situ method of nucleating gold or palladium nanoparticles in the presence of ethylene glycol as a reducing agent, while simultaneously reducing GO to graphene. The Au nanoparticles aid in spectroscopic characterization by both quenching fluorescence, allowing the graphene D and G bands to be quantified, and yielding a surface enhancement of about two orders of magnitude. We observe the excitation profile (488-785 nm) of the surface enhanced Raman spectrum (SERS) of graphene with Au nanoparticles adsorbed on the surface. Both the D and G bands display a resonance at approximately 593 nm (2.09 eV). This resonance may be interpreted as a combination of the plasmon resonance at 548 nm and a likely contribution from charge transfer as well. In addition, we observe a stiffening of the G band compared with that of graphene. The mechanism of the SERS, whether plasmonic or charge transfer-based, enables insight into the electronic pathways available to the graphene-nanoparticle system. We discuss our results in the context of several existing studies of graphene-based nanostructure derivatives.

Cronobacter (Enterobacter sakazakii): an opportunistic foodborne pathogen

Cronobacter spp. (Enterobacter sakazakii) are a recently described genus that is comprised of six genomospecies. The classification of these organisms was revised based on a detailed polyphasic taxonomic study. Cronobacter spp. are regarded as ubiquitous organisms having been isolated from a wide variety of foods. These bacteria are opportunistic pathogens and are linked with life-threatening infections in neonates. Clinical symptoms of Cronobacter infection include necrotizing enterocolitis, bacteremia, and meningitis, with case fatality rates of 50-80% being reported. Contaminated powdered infant formula has been epidemiologically linked with infections. Recently, infections among immunocompromised adults, mainly the elderly, have also been reported. A high tolerance to osmotic stress and elevated temperatures contribute to the survival of Cronobacter spp. in dried foods such as powdered infant formula. Controlling the organism in the production environment, thereby reducing dissemination, necessitates the provision of suitable diagnostic tools. Studies demonstrated that a high degree of variability exists amongst the phenotypic-based methods used to identify Cronobacter spp. However, advances in molecular detection and subtyping techniques have significantly improved the identification and characterization of Cronobacter spp. The dose required to induce infection has yet to be determined. In vitro virulence studies have shown that Cronobacter spp. may survive in macrophage cells and efficiently attach to and invade epithelial cell lines. The production of exopolysaccharide may contribute to the formation of biofilm and active efflux pumps promote resistance to antimicrobial agents such as bile salts and disinfectants. A holistic approach combining techniques such as comparative genome analysis, proteomics, and in vivo challenges could help unravel the complex interactions between this pathogen and its host. These data would help identify those properties in Cronobacter spp. which enable the bacterium to survive in the production environment and infect vulnerable neonates via the food chain.

Passive harmonic mode locking by mode selection in Fabry-Perot diode lasers with patterned effective index

We demonstrate passive harmonic mode locking of a quantum-well laser diode designed to support a discrete comb of Fabry-Perot modes. Spectral filtering of the mode spectrum was achieved using a nonperiodic patterning of the cavity effective index. By selecting six modes spaced at twice the fundamental mode spacing, near-transform-limited pulsed output with 2 ps pulse duration was obtained at a repetition rate of 100 GHz.