Complex postglacial recolonization inferred from population genetic structure of mottled sculpin Cottus bairdii in tributaries of eastern Lake Michigan, U.S.A.

This study used analyses of the genetic structure of a non-game fish species, the mottled sculpin Cottus bairdii to hypothesize probable recolonization routes used by cottids and possibly other Laurentian Great Lakes fishes following glacial recession. Based on samples from 16 small streams in five major Lake Michigan, U.S.A., tributary basins, significant interpopulation differentiation was documented (overall FST = 0·235). Differentiation was complex, however, with unexpectedly high genetic similarity among basins as well as occasionally strong differentiation within basins, despite relatively close geographic proximity of populations. Genetic dissimilarities were identified between eastern and western populations within river basins, with similarities existing between eastern and western populations across basins. Given such patterns, recolonization is hypothesized to have occurred on three occasions from more than one glacial refugium, with a secondary vicariant event resulting from reduction in the water level of ancestral Lake Michigan. By studying the phylogeography of a small, non-game fish species, this study provides insight into recolonization dynamics of the region that could be difficult to infer from game species that are often broadly dispersed by humans.

Multiple beam interference lithography: A tool for rapid fabrication of plasmonic arrays of arbitrary shaped nanomotifs.

A novel method enabling rapid fabrication of 2D periodic arrays of plasmonic nanoparticles across large areas is presented. This method is based on the interference of multiple coherent beams originating from diffraction of large-diameter collimated beam on a transmission phase mask. Mutual orientation of the interfering beams is determined by parameters of the used phase mask. Herein, parameters of the phase mask (periods and modulation depth) are selected to yield an interference pattern with high contrast and narrow well-separated maxima. Finally, multiple beam interference lithography (MBIL)-based fabrication of periodic plasmonic arrays with selected nanomotifs including discs, disc dimers, rods and bowtie antennas is demonstrated.

Flexible method based on four-beam interference lithography for fabrication of large areas of perfectly periodic plasmonic arrays.

A novel nanofabrication technique based on 4-beam interference lithography is presented that enables the preparation of large macroscopic areas (>50 mm2) of perfectly periodic and defect-free two-dimensional plasmonic arrays of nanoparticles as small as 100 nm. The technique is based on a special interferometer, composed of two mirrors and a sample with photoresist that together form a right-angled corner reflector. In such an interferometer, the incoming expanded laser beam is split into four interfering beams that yield an interference pattern with rectangular symmetry. The interferometer allows setting the periods of the array from about 220 nm to 1500 nm in both directions independently through the rotation of the corner-reflector assembly around horizontal and vertical axes perpendicular to the direction of the incident beam. Using a theoretical model, the implementation of the four-beam interference lithography is discussed in terms of the optimum contrast as well as attainable periods of the array. Several examples of plasmonic arrays (on either glass or polymer substrate layers) fabricated by this technique are presented.

Surface plasmon resonance optical cavity enhanced refractive index sensing.

We report on a method for surface plasmon resonance (SPR) refractive index sensing based on direct time-domain measurements. An optical resonator is built around an SPR sensor, and its photon lifetime is measured as a function of loss induced by refractive index variations. The method does not rely on any spectroscopic analysis or direct intensity measurement. Time-domain measurements are practically immune to light intensity fluctuations and thus lead to high resolution. A proof of concept experiment is carried out in which a sensor response to liquid samples of different refractive indices is measured. A refractive index resolution of the current system, extrapolated from the reproducibility of cavity-decay time determinations over 133 s, is found to be about 10(-5) RIU. The possibility of long-term averaging suggests that measurements with a resolution better than 10(-7) RIU/√Hz are within reach.

Real-time label-free monitoring of the cellular response to osmotic stress using conventional and long-range surface plasmons.

Cell volume and its regulation are key factors for cellular integrity and also serve as indicators of various cell pathologies. SPR sensors represent an efficient tool for real-time and label-free observations of changes in cell volume and shape. Here, we extend this concept by employing the use of long-range surface plasmons (LRSP). Due to the enhanced penetration depth of LRSP (~1µm, compared to ~0.4µm of a conventional surface plasmon), the observation of refractive index changes occurring deeper inside the cells is possible. In this work, the responses of a confluent normal rat kidney (NRK) epithelial cell layer to osmotic stress are studied by both conventional and long-range surface plasmons. Experiments are conducted in parallel using cell layers grown and stimulated under the same conditions to enable direct comparison of the results and discrimination of the osmotic stress-induced effects in different parts of the cell.

Detection of bisphenol A using a novel surface plasmon resonance biosensor.

We present a compact surface plasmon resonance (SPR) biosensor for the detection of bisphenol A (BpA), an endocrine-disrupting chemical. The biosensor is based on an SPR sensor platform (SPRCD) and the binding inhibition detection format. The detection of BpA in PBS and wastewater was performed at concentrations ranging from 0.05 to 1,000 ng/ml. The limit of detection for BpA in PBS and wastewater was estimated to be 0.08 and 0.14 ng/ml, respectively. It was also demonstrated that the biosensor can be regenerated for repeated use. Results achieved with the SPR biosensor are compared with those obtained using ELISA and HPLC methods.

Optical sensors based on spectroscopy of localized surface plasmons on metallic nanoparticles: sensitivity considerations.

Surface plasmon resonance (SPR) sensors use two types of surface plasmons: (i) propagating along a metal-dielectric interface and (ii) localized on metallic nano-objects. This article presents theoretical analysis of sensitivity of SPR sensors based on spectroscopy of localized surface plasmons on metallic nanoparticles. Analytical formulas inter-relating bulk and surface refractive index sensitivity with main design parameters are derived using the electrostatic approximation. The effect of particle diameter is accounted for by means of Mie theory. Figures of merit for SPR sensors using localized and propagating surface plasmons are calculated and compared. Although sensors based on spectroscopy of localized surface plasmons on gold spherical particles show promise for detection of processes occurring in the close proximity of the particle surface, their performance is still inferior to that of SPR sensors based on spectroscopy of propagating surface plasmons.

Multichannel SPR biosensor for detection of endocrine-disrupting compounds.

A surface plasmon resonance (SPR) biosensor for simultaneous detection of multiple organic pollutants exhibiting endocrine-disrupting activity, namely atrazine, benzo[a]pyrene, 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-nonylphenol, is reported. The biosensor utilizes a multichannel SPR sensor based on wavelength modulation of SPR and wavelength division multiplexing (WDM) of sensing channels, antibodies as biorecognition element and a competitive immunoassay detection format. An analysis time of 45 min (including 30-min incubation of the sample with antibodies) and limits of detection as low as 0.05, 0.07, 0.16 and 0.26 ng mL(-1) are demonstrated for benzo[a]pyrene, atrazine, 2,4-D and 4-nonylphenol, respectively. The biosensor is also shown to be regenerable and suitable for repeated use.

The influence of intrinsic coagulation pathway on blood platelets activation by oxidized cellulose.

Oxidized cellulose is an effective hemostat that works naturally to aid in blood coagulation. The mechanism of its action is not very well understood. Little effect on blood coagulation, but a pronounce decrease in platelet count has been reported upon the addition of the oxidized cellulose to the whole blood. As a marker of platelet activation and aggregation we used serotonin release reaction and turbidity changes in time. We found that oxidized cellulose did not activate washed platelets reconstituted in plasma-free medium or plasma-free medium with fibrinogen; no reduction of platelet count was observed. Serotonin release in platelet-rich plasma incubated with oxidized cellulose started in the range from 5 to 10 min. Serotonin release from platelets reconstituted in plasma deficient in either coagulation factor V, VIII, IX, or XII was delayed. Blood platelets activation by oxidized cellulose requires calcium ions present in dispersion of oxidized cellulose. Factor XIII deficiency had no influence on blood platelets activation by oxidized cellulose. Our results clearly indicate the significance of intrinsic coagulation pathway activation on blood platelets activation by oxidized cellulose and so indirectly on the hemostyptic effect of oxidized cellulose.

Hemostyptic effect of oxidized cellulose on blood platelets.

Cellulose is one of the hemostyptic biomaterials, which are able to initiate or accelerate blood coagulation at the site of their application. It belongs to surgical sealants. The mechanism of its action is not clearly understood. We studied the participation of blood platelets in this mechanism. As a marker of platelet activation we used serotonin release reaction. Serotonin release in platelet rich plasma incubated with various concentrations of oxidized cellulose (0.5%-2.0%) started in about 20 min. Washed platelets were not directly activated by oxidized cellulose within one hour. Washed platelets reconstituted in plasma obtained from two patients with coagulation factor XII deficiency were activated by oxidized cellulose with a prolonged lag phase. Our results demonstrate the significant influence of factor XII on blood platelets activation by oxidized cellulose.

A miniature fiber optic surface plasmon resonance sensor for fast detection of Staphylococcal enterotoxin B.

A fiber optic surface plasmon resonance (SPR) biosensor for detection of Staphylococcal enterotoxin B (SEB) is reported. The sensor is based on spectral interrogation of surface plasmons in a miniature sensing element based on a side-polished single-mode optical fiber with a thin metal overlayer. For specific detection of SEB, the SPR sensor is functionalized with a covalently crosslinked double-layer of antibodies against SEB. The SPR biosensor is demonstrated to be able to detect ng/ml concentrations of SEB in less than 10 min.

[Are echogenic foci in fetal heart ventricles insignificant findings?]. / Jsou echogenní fokusy srdecních komor plodu nevýznamným nálezem?

In a group of 7,721 foetuses with a high or low risk of cardiovascular pathology of the foetus, examined by complete foetal echocardiography, the authors found hyperechogenic ventricular structures in 211 foetuses (2.73% of the group) with a dominating localization in the left ventricle (97%). These structures are in the great majority a benign development variant which involves no risk for the development of the foetus. Rare localization beyond the left ventricle were not risk for the development of the foetus. Rare localization beyond the left ventricle were not associated with cardiac or other foetal pathologies. Echogenic ventricular focuses were not visualized by transvaginal echocardiography in the 13th week of pregnancy, although they were revealed in the same patient during the 21st week. Their presence does not affect left ventricular function and the function of the mitral valve pre-or postnatally. In the differential diagnosis these structures must be always differentiated from thrombi or cardiac tumours.

Interaction between fiber modes and surface plasmon waves: spectral properties.

The interaction between a guided mode of a single-mode optical fiber and a surface plasmon wave supported by a thin metal overlayer is studied. A theoretical description is given of this phenomenon based on the mode expansion and propagation method. It is demonstrated that the interaction can take place only within a narrow wavelength range therefore is manifested by a dip in the spectrum of the transmitted optical power. One can control the wavelength position of the dip by varying the refractive index of the superstate. Experimental study of the realized structure, consisting of a single-mode optical fiber with locally removed cladding and a thin gold overlayer, shows that the 2x10(-3) change in the refractive index of the superstrate shifts the dip by ~10 nm.

[Prenatal cardiology--current problems and the future]. / Prenatální kardiologie--soucasné problémy a budoucnost.

The author evaluates the past development, contemporary problems and future trends in the sphere of prenatal cardiology. As a basis he uses his own ten-year experience at a regional department of prenatal cardiology. He seeks the reasons for the stagnating, relatively low effectiveness of prenatal ultrasonic diagnostic screening to detect serious inborn heart disease which is one of the most frequent inborn foetal defects. The author discusses the association of this phenomenon with transformation changes of the system of health services. He deals with the approach of the child cardiologist to the parents of the affected foetus, possible pharmacological and non-pharmacological therapeutic approaches to prenatal cardiac pathology. It may be assumed that future progress of ultrasonographic technique will open the road from secondary to primary prevention of inborn heart disease.

[Transvaginal echocardiography in the early diagnosis of congenital heart defects in the human fetus]. / Transvaginální echokardiografie v casné diagnostice vrozených srdecních vad lidského plodu.

Transvaginal echocardiography makes it possible to diagnose serious congenital heart disease already during the first trimester of pregnancy. The authors present their experience with this examination method in pregnant women with a high risk of foetal cardiopathies and in women whose foetus is affected by another serious organ anomaly. The authors evaluate the successful visualization of the cardiac anatomy in different projections in relation to foetal age. They present the diagnosis of a serious inborn heart disease detected during the 15th week of gestation.

[Normal values of one-dimensional echocardiography of the heart ventricles in the fetus during the 18th to 38th week of pregnancy]. / Normální hodnoty jednorozmerné echokardiografie srdecních komor plodu v 18.-38. týdnu tehotenství.

The authors report normal values of one-dimensional echocardiography of the ventricles of foetuses obtained by analysis of high-standard 105 M-mode records of physiological foetuses aged 18-38 weeks. They assume their practical application by gynaecologists and child cardiologists during ultrasonographic screening of foetal pathology of the cardiovascular system.

[Regional differences in the prevalence of congenital heart defects]. / Krajové rozdíly výskytu vrozených srdecních vad.

Prevalence of congenital heart diseases was studied prospectively in all 664,218 infants live born in Bohemia from 1977 to 1984. All children who died were autopsied and those suspected of having a heart disease were examined at the specialized center. In total, 664/100,000 infants were born with a heart defect, most of them in Prague (957,9/100,000) and in Central Bohemia (739.4) and in Northern Bohemia (619.3). The lowest prevalence was found in West Bohemia (515.1/100000 live births). The relative frequency of congenital heart defect categories differed significantly among regions. Evidence of regional differences in prevalence of congenital heart diseases and their forms suggests that environmental factors can play an important role in the etiology of congenital heart defects.

[Tumor of the left atrium and supraventricular tachycardia in the fetus--prenatal diagnosis and treatment]. / Tumor levé síne a supraventrikulární tachykardie plodu--prenatální diagnóza a lécba.

During the 29th week of gestation the authors diagnosed supraventricular tachycardia of the foetus and pathological echogenity in the region of the mitral valve, most probably of tumourous aetiology. By transplacental digitalization the supraventricular tachycardia was controlled; according to Doppler analysis the tumour did not interfere with the flow to the mitral orifice. Post-natally the diagnosis of a tumour in the left atrium was confirmed. Surgery was so far postponed in view of the normal haemodynamics.

[The incidence of heart defects in children]. / Výskyt srdecních vad u deti.

By examining all of 91,823 children born in 1980 in Bohemia, congenital heart disease was proved in 589 (6.415/1000 liveborns) and cardiomyopathy in 24 (0.261/1000 liveborns). Further 166 (1.808/1000 liveborns) were follow-up with a diagnosis of congenital heart disease by pediatric cardiologists in the field, but at the age of 4 years we didn't prove the defect any more. Prevalence of heart defects: ventricular septal defect (31.4%), atrial septal defect (11.4%), aortic stenosis (7.6%), pulmonary stenosis (7.1%), coarctation of the aorta (5.8%), transposition of the great arteries (5.4%), patent ductus arteriosus (4.8%), atrioventricular canal and hypoplastic left heart (4.1%), tetralogy of Fallot (3.6%). Other defects occurred less frequently than in 2.5% of all congenital heart disease.