Dinophysis toxins: causative organisms, distribution and fate in shellfish

Several Dinophysis species produce diarrhoetic toxins (okadaic acid and dinophysistoxins) and pectenotoxins, and cause gastointestinal illness, Diarrhetic Shellfish Poisoning (DSP), even at low cell densities (<103 cells·L⁻¹). They are the main threat, in terms of days of harvesting bans, to aquaculture in Northern Japan, Chile, and Europe. Toxicity and toxin profiles are very variable, more between strains than species. The distribution of DSP events mirrors that of shellfish production areas that have implemented toxin regulations, otherwise misinterpreted as bacterial or viral contamination. Field observations and laboratory experiments have shown that most of the toxins produced by Dinophysis are released into the medium, raising questions about the ecological role of extracelular toxins and their potential uptake by shellfish. Shellfish contamination results from a complex balance between food selection, adsorption, species-specific enzymatic transformations, and allometric processes. Highest risk areas are those combining Dinophysis strains with high cell content of okadaates, aquaculture with predominance of mytilids (good accumulators of toxins), and consumers who frequently include mussels in their diet. Regions including pectenotoxins in their regulated phycotoxins will suffer from much longer harvesting bans and from disloyal competition with production areas where these toxins have been deregulated.

Regulation of reactionary dentin formation by odontoblasts in response to polymicrobial invasion of dentin matrix

Odontoblast synthesis of dentin proceeds through discrete but overlapping phases characterized by formation of a patterned organic matrix followed by remodelling and active mineralization. Microbial invasion of dentin in caries triggers an adaptive response by odontoblasts, culminating in formation of a structurally altered reactionary dentin, marked by biochemical and architectonic modifications including diminished tubularity. Scanning electron microscopy of the collagen framework in reactionary dentin revealed a radically modified yet highly organized meshwork as indicated by fractal and lacunarity analyses. Immuno-gold labelling demonstrated increased density and regular spatial distribution of dentin sialoprotein (DSP) in reactionary dentin. DSP contributes putative hydroxyapatite nucleation sites on the collagen scaffold. To further dissect the formation of this altered dentin matrix, the associated enzymatic machinery was investigated. Analysis of extracted dentin matrix indicated increased activity of matrix metalloproteinase-2 (MMP-2) in the reactionary zone referenced to physiologic dentin. Likewise, gene expression analysis of micro-dissected odontoblast layer revealed up-regulation of MMP-2. Parallel up-regulation of tissue inhibitor of metalloproteinase-2 (TIMP-2) and membrane type 1- matrix metalloproteinase (MT1-MMP) was observed in response to caries. Next, modulation of odontoblastic dentinogenic enzyme repertoire was addressed. In the odontoblast layer expression of Toll-like receptors was markedly altered in response to bacterial invasion. In carious teeth TLR-2 and the gene encoding the corresponding adaptor protein MyD88 were down-regulated whereas genes encoding TLR-4 and adaptor proteins TRAM and Mal/TIRAP were up-regulated. TLR-4 signalling mediated by binding of bacterial products has been linked to up-regulation of MMP-2. Further, increased expression of genes encoding components of the TGF-β signalling pathway, namely SMAD-2 and SMAD-4, may explain the increased synthesis of collagen by odontoblasts in caries. These findings indicate a radical adaptive response of odontoblasts to microbial invasion of dentin with resultant synthesis of modified mineralized matrix.

A new strategy for fast radiofrequency CW EPR imaging: direct detection with rapid scan and rotating gradients

Rapid field scan on the order of T/s using high frequency sinusoidal or triangular sweep fields superimposed on the main Zeeman field, was used for direct detection of signals without low-frequency field modulation. Simultaneous application of space-encoding rotating field gradients have been employed to perform fast CW EPR imaging using direct detection that could, in principle, approach the speed of pulsed FT EPR imaging. The method takes advantage of the well-known rapid-scan strategy in CW NMR and EPR that allows arbitrarily fast field sweep and the simultaneous application of spinning gradients that allows fast spatial encoding. This leads to fast functional EPR imaging and, depending on the spin concentration, spectrometer sensitivity and detection band width, can provide improved temporal resolution that is important to interrogate dynamics of spin perfusion, pharmacokinetics, spectral spatial imaging, dynamic oxymetry, etc.

Protein tyrosine and serine-threonine phosphatases in the sea urchin, Strongylocentrotus purpuratus: identification and potential functions

Protein phosphatases, in coordination with protein kinases, play crucial roles in regulation of signaling pathways. To identify protein tyrosine phosphatases (PTPs) and serine-threonine (ser-thr) phosphatases in the Strongylocentrotus purpuratus genome, 179 annotated sequences were studied (122 PTPs, 57 ser-thr phosphatases). Sequence analysis identified 91 phosphatases (33 conventional PTPs, 31 dual specificity phosphatases, 1 Class III Cysteine-based PTP, 1 Asp-based PTP, and 25 ser-thr phosphatases). Using catalytic sites, levels of conservation and constraint in amino acid sequence were examined. Nine of 25 receptor PTPs (RPTPs) corresponded to human, nematode, or fly homologues. Domain structure revealed that sea urchin-specific RPTPs including two, PTPRLec and PTPRscav, may act in immune defense. Embryonic transcription of each phosphatase was recorded from a high-density oligonucleotide tiling microarray experiment. Most RPTPs are expressed at very low levels, whereas nonreceptor PTPs (NRPTPs) are generally expressed at moderate levels. High expression was detected in MAP kinase phosphatases (MKPs) and numerous ser-thr phosphatases. For several expressed NRPTPs, MKPs, and ser-thr phosphatases, morpholino antisense-mediated knockdowns were performed and phenotypes obtained. Finally, to assess roles of annotated phosphatases in endomesoderm formation, a literature review of phosphatase functions in model organisms was superimposed on sea urchin developmental pathways to predict areas of functional activity.

Precursors of delayed sleep phase in adolescence: a population-based longitudinal study

Study Objective

The aim of this study was to assess sleep behavior, sleep problems and mental health in childhood as possible candidate precursors for the development of delayed sleep phase (DSP) during adolescence.

Methods

A longitudinal cohort study of 2200 children at age 7-9 (T1), 11-13 (T2), and 16-19 (T3) years. DSP was assessed at T3, and mental health problems by the Strength and Difficulties Questionnaire and time in bed and sleep problems at T1 and T2. Logistic regression analyses were used to examine associations between sleep and mental health at T1 and T2, and subsequent DSP at T3. Estimated marginal means were computed to compare mental health at T1 and T2 in adolescents with and without DSP.

Results

Sleeping less than 9 hours per night at age 11-13 was significantly associated with DSP at 16-19 years (adjusted odds ratio = 3.37). Sleep problems at 11-13 years of age were more frequent among those who developed DSP compared to children who did not develop DSP (20% vs. 12%) but the results did not remain significant when controlling for early mental health problems. Sleep problems and mental health at 7-9 years of age was not related to later DSP. In the crude analyses, all Strengths and Difficulties Questionnaire (SDQ) subscales at 11-13 years was significantly associated with later DSP, but in the fully adjusted analysis, only the SDQ total score and hyperactivity subscale remained statistically significant.

Conclusion

Children with DSP in adolescence possess identifiable risk indicators in childhood.

Digital hearing AIDS from the perspective of one consumer/audiologist

Recent developments in hearing aids are reviewed in the context of the author's personal experience as an audiologist and as a hearing aid wearer. The need for evidence of benefit specific to digital signal processing in hearing aids is stressed, as well as addressing cost-benefit ratios in view of the high cost of digital hearing aids.

Integration of digital signal processing technologies with pulsed electron paramagnetic resonance imaging

The integration of modern data acquisition and digital signal processing (DSP) technologies with Fourier transform electron paramagnetic resonance (FT-EPR) imaging at radiofrequencies (RF) is described. The FT-EPR system operates at a Larmor frequency (L(f)) of 300MHz to facilitate in vivo studies. This relatively low frequency L(f), in conjunction with our approximately 10MHz signal bandwidth, enables the use of direct free induction decay time-locked subsampling (TLSS). This particular technique provides advantages by eliminating the traditional analog intermediate frequency downconversion stage along with the corresponding noise sources. TLSS also results in manageable sample rates that facilitate the design of DSP-based data acquisition and image processing platforms. More specifically, we utilize a high-speed field programmable gate array (FPGA) and a DSP processor to perform advanced real-time signal and image processing. The migration to a DSP-based configuration offers the benefits of improved EPR system performance, as well as increased adaptability to various EPR system configurations (i.e., software configurable systems instead of hardware reconfigurations). The required modifications to the FT-EPR system design are described, with focus on the addition of DSP technologies including the application-specific hardware, software, and firmware developed for the FPGA and DSP processor. The first results of using real-time DSP technologies in conjunction with direct detection bandpass sampling to implement EPR imaging at RF frequencies are presented.

Is genomic screening necessary for fetuses who suffer moderate to severe tricuspid regurgitation?: A case report

RATIONALE

Tricuspid regurgitation (TR) is a frequent finding during echocardiography screening in fetal or neonatal life, which reveals a weak association between TR and cardiac malformation. Except for structural abnormalities, dilated cardiomyopathy (DCM) ranks as the top reason for early child morbidity and mortality among all kinds of cardiomyopathy. In the early fetal stage, cardiac abnormalities detected by early fetal genetic testing followed by abnormalities on ultrasound would provide more valuable information for parents and physicians to make a better therapeutic schedule.

PATIENT CONCERNS

A case of severe TR was found via the fetal ultrasound screening. After birth, this child suffered severe heart dysfunction, and echocardiography confirmed a DCM phenotype within a very short time.

DIAGNOSIS AND INTERVENTION

A 40-year-old female received routine fetal echocardiographic screening, which demonstrated that the fetus presented severe TR. Six months after birth, the baby experienced severe heart failure, as the EF dropped to 22% with an extremely large LV chamber. The genomic sequence had been determined, and 3 pathogenic gene mutations located in 2 genes, cardiac troponin T (TNNT2) c.548G>A, desmoplakin (DSP) c.3146C>T, and DSP c.5213G>A, were identified. Finally, the patient was diagnosed with DCM. This child received digoxin, hydrochlorothiazide, spironolactone diuresis, captopril, and L-carnitine, and the symptoms of heart failure had been controlled as the patient waited for heart transplantation.

OUTCOMES

During the follow-up, the patient still suffered from poor heart function and an enlarged left ventricle. Concomitantly, the parents placed her on a waiting list for heart transplantation.

LESSONS

Fetal TR is a common phenomenon, and many studies have indicated that isolated TR is not an appropriate predictor of chromosomal abnormalities or congenital heart defects. However, according to this case, it is urgent to recommend that the mother should take advantage of free fetal DNA analysis in a maternal blood sample to obtain further molecular evidence once fetal echocardiography reveals moderate to severe TR with any maternal high-risk factors for birth defects.