Ultrafast all-optical toggle writing of magnetic bits without relying on heat.

Ultrafast excitation of matter can violate Curie's principle that the symmetry of the cause must be found in the symmetry of the effect. For instance, heating alone cannot result in a deterministic reversal of magnetization. However, if the heating is ultrafast, it facilitates toggle switching of magnetization between stable bit-states without any magnetic field. Here we show that the regime of ultrafast toggle switching can be also realized via a mechanism without relying on heat. Ultrafast laser excitation of iron-garnet with linearly polarized light modifies magnetic anisotropy and thus causes toggling magnetization between two stable bit states. This new regime of 'cold' toggle switching can be observed in ferrimagnets without a compensation point and over an exceptionally broad temperature range. The control of magnetic anisotropy required for the toggle switching exhibits reduced dissipation compared to laser-induced-heating mechanism, however the dissipation and the switching-time are shown to be competing parameters.

Single-shot imaging of ultrafast all-optical magnetization dynamics with a spatiotemporal resolution.

We present a laboratory system for single-shot magneto-optical (MO) imaging of ultrafast magnetization dynamics with less than 8 fs temporal, micrometer spatial resolutions and a MO Faraday's rotation sensitivity of 4 mdeg/µm. We create a stack of MO images repeatedly employing a single pair of pump and defocused probe pulses to induce and visualize MO changes in the sample. Both laser beams are independently wavelength-tunable, allowing for a flexible, resonant adjustable two-color pump and probe scheme. To increase the MO contrast, the probe beam is spatially filtered through a 50 µm aperture. We performed the all-optical switching experiment in Co-doped yttrium iron garnet films (YIG:Co) to demonstrate the capability of the presented method. We determine the spatiotemporal distribution of the effective field of photo-induced anisotropy, driving the all-optical switching of the magnetization in the YIG:Co film without an external magnetic field. Moreover, using this imaging method, we tracked the process of the laser-induced magnetization precession.

Induction of gynogenetic and androgenetic haploid and doubled haploid development in the brown trout (Salmo trutta Linnaeus 1758).

Gynogenetic and androgenetic brown trout (Salmo trutta Linnaeus 1758) haploids (Hs) and doubled haploids (DHs) were produced in the present research. Haploid development was induced by radiation-induced genetic inactivation of spermatozoa (gynogenesis) or eggs (androgenesis) before insemination. To provide DHs, gynogenetic and androgenetic haploid zygotes were subjected to the high pressure shock to suppress the first mitotic cleavage. Among haploids, gynogenetic embryos were showing lower mortality when compared to the androgenetic embryos; however, most of them die before the first feeding stage. Gynogenetic doubled haploids provided in the course of the brown trout eggs activation performed by homologous and heterologous sperm (rainbow trout) were developing equally showing hatching rates of 14.76 ± 2.4% and 16.14 ± 2.90% and the survival rates at the first feeding stage of 10.48 ± 3.48% and 12.78 ± 2.18%, respectively. Significantly, lower survival rate was observed among androgenetic progenies from the diploid groups with only few specimens that survived to the first feeding stage. Cytogenetic survey showed that among embryos from the diploid variants of the research, only gynogenetic individuals possessed doubled sets of chromosomes. Thus, it is reasonable to assume that radiation employed for the genetic inactivation of the brown trout eggs misaligned mechanism responsible for the cell divisions and might have delayed or even arrested the first mitotic cleavage in the androgenetic brown trout zygotes. Moreover, protocol for the radiation-induced inactivation of the paternal and maternal genome should be adjusted as some of the cytogenetically surveyed gynogenetic and androgenetic embryos exhibited fragments of the irradiated chromosomes.

Effect of postthaw storage time and sperm-to-egg ratio on fertility of cryopreserved brook trout sperm.

The aim of this study was to test the influence of postthaw storage time on sperm motility parameters of brook trout (n = 9). Furthermore, we examined the effect of sperm-to-egg ratios of 300,000:1 and 600,000:1 on fertility of postthaw, cryopreserved, brook trout sperm. The application of a cryopreservation procedure produced very high postthaw sperm motility (56.8 ± 4.0%). The cryopreserved sperm of brook trout could be stored up to 60 minutes without loss of the percentage of sperm motility (52.0 ± 9.0%). The fertilization capacity of brook trout postthaw sperm was comparable with the fertilization rate of fresh semen at a sperm-to-egg ratio as low as 300,000:1 (42.4 ± 14.0% and 36.5 ± 11.0% for eyed and hatched stages, respectively). The possibility of postthaw semen storage for the prolonged time and the obtainment of high fertilization rate at low sperm-to-egg ratio can lead to the significant improvement of brook trout semen cryopreservation procedure.

Use of eggs derived from the interspecific charr hybrids to induce androgenetic development of the brook charr (Salvelinus fontinalis Mitchill 1814).

Although, brook charr (Salvelinus fontinalis Mitchill 1814) and Arctic charr (Salvelinus alpinus Linnaeus 1758) are able to cross and give fertile offspring, their androgenetic nucleocytoplasmic hybrids are not viable. To overcome incompatibility between the egg cytoplasm of one charr species and the sperm nucleus of another charr species, application of F1 interspecific hybrids as egg donors for the purpose of androgenesis has been proposed. Here, androgenetic development of the brook charr was successfully induced in the brook charr eggs and the eggs derived from the reciprocal brook charr × Arctic charr F1 hybrids. A working androgenesis protocol included inactivation of the maternal nuclear DNA achieved by irradiation of the eggs with 420 Gy of X-rays, insemination of such treated eggs with the haploid sperm cells and exposition of the haploid androgenetic zygotes to the high hydrostatic pressure shock (51.711 MPa for 4 min) applied 420 min after insemination. Androgenetic larvae that hatched from the brook charr and the hybrid eggs were shown to be homozygous brook charr individuals. Androgenetic individuals exhibited 84 chromosomes and 100 chromosome arms (FN), values characteristic for the brook charr diploid cells. Strategy hybridize first than induce androgenesis should be tested in order to provide androgenetic offspring in other salmonids that are able to cross and produce fertile offspring.

Dioctahedral smectite neutralization activity of Clostridium difficile and Bacteroides fragilis toxins in vitro.

The neutralization activity of dioctahedral smectite for ten toxigenic Clostridium difficile and eight enterotoxigenic Bacteroides fragilis strains was studied using McCoy and HT 29/C1 cell lines, respectively. Minimalization of the cytopathic effect of C. difficile toxin B on McCoy cell lines by dioctahedral smectite dissolved in PBS was observed. After incubation with dioctahedral smectite the toxic effects of B. fragilis enterotoxins on HT/29C1 (human colon adenocarcinoma cell line) were eliminated. Best neutralization of B. fragilis toxin was achieved using dioctahedral smectite dissolved in BHI.

[Activity and molecular form of intestinal gamma-glutamyltransferase (GGT) EC 2.3.2.2. in celiac disease]. / Aktywnosc i postac molekularna jelitowej gammaglutamylotransferazy (GGT) EC 2.3.2.2. w celiakii.

It has been shown that GGT activity in the duodenal biopsy homogenates of the children with coeliac disease (n-10) in remission (1 to 3 years of gluten-free diet) is lower than in those with other gastrointestinal tract diseases (n-6). In children with coeliac disease after gluten challenge (1 g of gluten) kg BW for 3 to 6 months) the GGT activity decreased fourfold (n-10). After a few months of gluten challenge there was in coeliac children (n-5) a marked predominance of GGT without sialic acid (the asialic GGT). Similarly there was a prevalence of this form (n-5) in the gut tissue of 3 month old human fetus. In the homogenates of the duodenal bioptates of the children with other gastrointestinal tract diseases (n-6) there was a predominance of the sialic form of the GGT. In the gut tissue of children older than 3 years (n-6) and adults who died of reasons other than gastrointestinal a marked predominance of the sialic form of GGT was found. It has been suggested that presence of asialic form of GGT in coeliac disease is connected with the lectin-like activity of gluten. The process of sialization or desialization takes place within or outside enterocytes. It changes the gut permeability and causes a secondary reaction to the penetrating allergens.

[Evaluation of the effect of gluten-free diet on nutritional status of children with florid celiac disease]. / Ocena wplywu diety bezglutenowej na stan odzywienia dzieci z celiakia "kwitnaca".

A dynamics of Nutritional Status of 55 children with recently diagnosed coeliac disease was assessed during the treatment with gluten free diet. No deterioration of the nutritional status was seen in 34.1% of the investigated children (time 0) whereas different degree of nutritional deficiency was noted in the remaining 75.9% of children including 10% of children with severe deficiency. After a 2-year therapy with gluten-free diet a deteriorated nutritional status was only found in 8.6% of children. In 27 children with gluten free diet for nearly 3 years, with maintenance of histological remission, the percentage of children with nutritional deficiency was 7.2%. The fact of normal Nutritional Status in more than 30% of the investigated coeliac children at the time of the initial diagnosis seems to be an effect of early and proper initial diagnosis.

[The effect of 6-month provocation with gluten on the height and weight of children with celiac disease]. / Wplyw 6-miesiecznej prowokacji glutenem na wysokosc i mase ciala u dzieci z celiakia.

Gluten challenge was performed in 22 coeliac children in the period of histological remission. Gluten in dose 0.5 g/kg was administered for 6 months. Before the Provocation Test over 60% of children have had body weight over 50 c for normal children in Warsaw. Standardized mean body weight (+ 0.13 +/- 1.1) and height (+ 0.04 +/- 1.05) of the investigated coeliac children did not differ significantly from the values of normal Warsaw population (p greater than 0.005). A 6 month provocation with gluten leading to the histological relapse did not affect body weight and height of tested children; over 50% have had body weight and height over 50 c. Mean standardized body weight (- 0.002 +/- 1.0) and height height (-0.07 +/- 0.91) did not differ significantly from the normal values (p greater than 0.05) and corresponding values before the provocation (p greater than 0.05). It seems that Provocation Test with gluten carried out in the above way does not inhibit physical development of children with coeliac disease.

Disease specificity and dynamics of changes in IgA class anti-endomysial antibodies in celiac disease.

We evaluated the sensitivity and kinetics of serum IgA class anti-endomysial antibodies in the diagnosis of celiac disease (CD) as established by the criteria of the European Society for Pediatric Gastroenterology and Nutrition (ESPGAN). Eighty-four cases that satisfied the ESPGAN criteria for CD were evaluated for IgA-EmA titers during various phases of establishing the diagnosis. Thirty-three cases were infants and children less than 5 years of age undergoing intestinal biopsies for symptoms of CD and 51 were previously diagnosed adults. Of the 33 children, 11 were untreated and symptomatic and were IgA-EmA positive at initial presentation. Twenty-two children previously controlled on a gluten-free diet (GFD) exhibited IgA-EmA titers during gluten challenge. Furthermore, the antibody levels declined in all cases (usually to negative) when the patients were again placed on a GFD for 6-12 months. Changes in intestinal histopathology paralleled the changes in antibody titers in six cases undergoing serial biopsies. Of the 51 adult patients with proven CD who were prescribed a GFD for at least 12 months, IgA-EmA were detected in 10 cases who were noncompliant to their GFD, whereas the antibodies was found in only 1 of the remaining 41 patients strictly adhering to their diet. The sera of 140 aged-matched children with various intestinal problems, 87 healthy adults, and 67 patients with dermatological diseases served as controls and were also IgA-EmA negative. On the basis of these findings, we suggest a role for the IgA-EmA as a serological screening test for active CD. It further offers the potential for monitoring compliance to diet in established cases of CD and also indicates the proper timing for biopsy in patients undergoing evaluation of CD.