Galanin gene expression and effects of its knock-down on the development of the nervous system in larval zebrafish

Despite the known importance of galanin in the nervous system of vertebrates, the galanin gene structure and expression and the consequences of galanin deficiency in developing zebrafish are unknown. We cloned the galanin gene and analyzed its expression by using in situ hybridization, PCR, and immunocytochemistry throughout the early development of zebrafish until the end of the first week of life. The single zebrafish galanin gene encoded for a single amidated galanin peptide and a galanin message-associated peptide. Two forms resulting from alternative processing were identified. Galanin mRNA was maternally expressed and found in developing fish throughout early development. In situ hybridization showed the first positive neurons in three groups in the brain at 28 hours postfertilization. At 2 days postfertilization, three prosencephalic neuron groups were seen in the preoptic area and in rostral and caudal periventricular hypothalamus. In addition, two other groups of weakly stained neurons were visible, one in the midbrain and another in the hindbrain. Translation inhibition of galanin mRNA with morpholino oligonucleotides caused complete disappearance of galanin immunoreactivity in the brain until 7 dpf and did not induce known cascades of nonspecific pathways or morphological abnormalities. A minor disturbance of sensory ganglia was found. Galanin knockdown did not alter the expression of tyrosine hydroxylases 1 and 2, choline acetyltransferase, histidine decarboxylase, or orexin mRNA. The results suggest that galanin does not regulate the development of these key markers of specific neurons, although galanin-expressing fibers were in a close spatial proximity to several neurons of these neuronal populations.

Radiofrequency-induced small bowel thermofusion: an ex vivo study of intestinal seal adequacy using mechanical and imaging modalities

BACKGROUND

Bipolar radiofrequency (RF) induced tissue fusion is believed to have the potential to seal and anastomose intestinal tissue thereby providing an alternative to current techniques which are associated with technical and functional complications. This study examines the mechanical and cellular effects of RF energy and varying compressive pressures when applied to create ex vivo intestinal seals.

METHODS

A total of 299 mucosa-to-mucosa fusions were formed on ex vivo porcine small bowel segments using a prototype bipolar RF device powered by a closed-loop, feedback-controlled RF generator. Compressive pressures were increased at 0.05 MPa intervals from 0.00 to 0.49 MPa and RF energy was applied for a set time period to achieve bowel tissue fusion. Seal strength was subsequently assessed using burst pressure and tensile strength testing, whilst morphological changes were determined through light microscopy. To further identify the subcellular tissue changes that occur as a result of RF energy application, the collagen matrix in the fused area of a single bowel segment sealed at an optimal pressure was examined using transmission electron microscopy (TEM).

RESULTS

An optimal applied compressive pressure range was observed between 0.10 and 0.25 MPa. Light microscopy demonstrated a step change between fused and unfused tissues but was ineffective in distinguishing between pressure levels once tissues were sealed. Non uniform collagen damage was observed in the sealed tissue area using TEM, with some areas showing complete collagen denaturation and others showing none, despite the seal being complete. This finding has not been described previously in RF-fused tissue and may have implications for in vivo healing.

CONCLUSIONS

This study shows that both bipolar RF energy and optimal compressive pressures are needed to create strong intestinal seals. This finding suggests that RF fusion technology can be effectively applied for bowel sealing and may lead to the development of novel anastomosis tools.

Note: Near-field imaging of thermal radiation at low temperatures by passive millimeter-wave microscopy

Imaging of thermal radiation with a spatial resolution below the diffraction limit is demonstrated with a passive millimeter-wave microscope. This technique utilizes a sensitive radiometric receiver in combination with a scanning near-field microscope. Experiments were performed at 50 GHz (λ = 6 mm) with sample temperatures ranging from room temperature down to 160 K, and the performance was shown to be superior to that achieved with passive imaging systems in the infrared region. The images are affected by non-uniformities in the transmission of thermal radiation from the sample to the receiver via the near-field probe and the reflection of thermal radiation back to the receiver from the probe. The effects of these non-uniformities were successfully removed using a sample image acquired by active measurements using a vector network analyzer.

Non-seasonal changes in the intensity of female mate preference and offspring sex ratio in the wild guppy Poecilia reticulata

It has been demonstrated that the exaggeration of male sexual ornaments and the intensity of female mate preferences of a wild guppy population change over a period of several months. However, the factors that determine the short-term changes in male ornaments and female preferences remained unclear. In this study, we examined the effect of season on these short-term changes by measuring these traits in the same seasons of different years for a wild guppy population in Okinawa, Japan. We also compared the characteristics of the offspring in each collection term, as female guppies are known to have the ability to control offspring characteristics, such as brood size and sex ratios, depending on their mates' attractiveness. Results showed that the total lengths of the males changed seasonally; males in the summer were larger than those in the spring. In contrast, the size of orange spots in males and the intensity of female mating preferences differed in the same seasons of different years. Brood size and offspring body size in each term showed seasonal changes. However, offspring sex ratios exhibited different patterns in the same seasons of different years. Females produced female-biased broods when attractive males with large orange spots were rare. These results suggest that short-term changes in some traits of adult male and female guppies as well as offspring sex ratios may be not determined by seasonal factors, and that these traits may be interrelated.

Quantifying hepatic steatosis - more than meets the eye

AIMS

The non-alcoholic fatty liver disease (NAFLD) activity score (NAS) is the histological tool used to assess disease severity based on steatosis, inflammation and hepatocyte ballooning. As steatosis contributes up to three of a potential eight points to NAS, it is important to quantify steatosis accurately. We sought to determine the optimum histological technique for identifying fat in tissue.

METHODS AND RESULTS

Using tissue from a mouse model of NAFLD, with validation in human liver biopsies, the percentage steatosis and fat droplet size were assessed in haematoxylin and eosin (H&E)- and Oil Red-O (ORO)-stained sections by light microscopy and digital image analysis (DIA). Results were compared to biochemical tissue triglyceride content and MRI assessment of hepatic lipid content. H&E steatosis assessment correlated poorly with tissue triglyceride concentration. However, ORO DIA exhibited much higher sensitivity and specificity for steatosis and correlated very well with triglyceride concentration in mouse and human liver (R = 0.706, P = 0.001 and R = 0.894, P =0.041, respectively). MRI-based assessment of steatosis was inaccurate.

CONCLUSIONS

ORO DIA is the most accurate method for detecting and quantifying steatosis. Although H&E-based NAS remains clinically valid in both clinical research and experimental situations, ORO DIA is a more robust technique to assess liver steatosis accurately for NAS scoring.

Multi-excitation fluorescence spectroscopy for analysis of non-alcoholic fatty liver disease

BACKGROUND AND OBJECTIVES

The increasing incidence of non-alcoholic fatty liver diseases (NAFLD) and the consequent progression to cirrhosis is expected to become a major cause of liver transplantation. This will exacerbate the organ donor shortage and mean that 'marginal' fatty liver grafts are more frequently used. Autofluorescence spectroscopy is a fast, objective, and non-destructive method to detect change in the endogenous fluorophores distribution and could prove to be a valuable tool for NAFLD diagnosis and transplant graft assessment.

MATERIALS AND METHODS

A system was constructed consisting of a fibre probe with two laser diodes that provided excitation light at 375 and 405 nm, and an imaging spectrograph system. This was used to distinguish fluorescence spectra acquired from the harvested livers from mice with NAFLD of differing severity (healthy, mild steatotic and steatohepatitic). The fluorescence data were entered into a sparse multiclass probabilistic algorithm for disease classification. Histopathology, thiobarbituric acid reactive substances (TBARS) and alanine transaminase (ALT) assays were conducted in addition to the fluorescence measurements

RESULTS

TBARS and ALT assays enabled differentiation of the steatohepatitic group from the mild steatosis and control groups (P ≤ 0.028) but failed to separate the mild steatotic group from the control group. The three groups were all clearly differentiated from each other using fluorescence spectroscopy, and classification accuracy was found to be 95%.

CONCLUSION

Fluorescence spectroscopy appears to be a promising approach for the analysis of diseased liver tissue.

Impact of pan-caspase inhibition in animal models of established steatosis and non-alcoholic steatohepatitis

BACKGROUND & AIMS

Non-alcoholic fatty liver disease is a progressive condition comprising steatosis, steatohepatitis, and cirrhosis. Caspase activation mediates apoptosis and the inflammatory response. Studies demonstrate increased apoptotic activity in NASH although its pathophysiological importance is uncertain. We sought to determine the effects of irreversible pan-caspase inhibition in murine models of established steatosis (high fat diet, HFD) and steatohepatitis (methionine-choline deficient diet, MCD).

METHODS

In one study arm, male C3H/HeN mice were fed HFD; in the other, Db/Db mice were fed MCD. Once disease was established, animals were randomised to receive caspase inhibitor (VX-166), TPGS/PEG vehicle or no additional therapy until the end of the study. Biochemical and histological indices were examined to determine NASH activity and tissue oxidative stress. Apoptotic activity and cell turnover were assessed immunohistochemically by staining for caspase-cleaved CK-18 and PCNA.

RESULTS

MCD and HFD significantly increased apoptosis, which was reduced by VX-166 treatment. VX-166 did not reduce steatosis but reduced histological inflammation, serum ALT levels, and oxidative stress, particularly in the MCD model. TPGS/PEG vehicle also exhibited some anti-inflammatory activity.

CONCLUSIONS

In both models, VX-166 inhibited apoptosis and reduced histological inflammatory infiltrate although there was a more modest impact on other indices of liver injury. In addition, TPGS/PEG vehicle also exhibited some anti-inflammatory activity, likely through the antioxidant effects of vitamin E and changes in gut flora/mucosal interactions. These data suggest that caspase inhibition may represent a valid therapeutic approach; however, further studies to assess the long-term value of more selective caspase inhibition are merited.

Relative importance of the area and intensity of the orange spots of male guppies Poecilia reticulata as mating traits preferred by females

Digitally modified videos of male guppies Poecilia reticulata were used to examine the relative importance of the area and intensity of the orange spots as mating traits preferred by females. The females prioritized the area of the orange spots over intensity for their mate preference.

The comparative neuroanatomy and neurochemistry of zebrafish CNS systems of relevance to human neuropsychiatric diseases

Modulatory neurotransmitters which signal through G protein-coupled receptors control brain functions which deteriorate in degenerative brain diseases. During the past decade many of these systems have been mapped in the zebrafish brain. The main architecture of the systems in zebrafish brain resembles that of the mammals, despite differences in the development of the telencephalon and mesodiencephalon. Modulatory neurotransmitters systems which degenerate in human diseases include dopamine, noradrenaline, serotonin, histamine, acetylcholine and orexin/hypocretin. Although the number of G protein-coupled receptors in zebrafish is clearly larger than in mammals, many receptors have similar expression patterns, binding and signaling properties as in mammals. Distinct differences between mammals and zebrafish include duplication of the tyrosine hydroxylase gene in zebrafish, and presence of one instead of two monoamine oxidase genes. Zebrafish are sensitive to neurotoxins including MPTP, and exposure to this neurotoxin induces a decline in dopamine content and number of detectable tyrosine hydroxylase immunoreactive neurons in distinct nuclei. Sensitivity to important neurotoxins, many available genetic methods, rapid development and large-scale quantitative behavioral methods in addition to advanced quantitative anatomical methods render zebrafish an optimal organism for studies on disease mechanisms.

Extraction behavior of rutherfordium into tributylphosphate from hydrochloric acid

The extraction behavior of rutherfordium (Rf) into tributylphosphate (TBP) from hydrochloric acid (HCl) has been studied together with those of the lighter group-4 elements Zr and Hf. The extractability of261Rf,169Hf, and85Zr into TBP was investigated under identical conditions in 7.2–8.0 M HCl by on-line reversed-phase extraction chromatography. The percent extractions of Rf, Hf, and Zr into the TBP resin increase steeply with increasing HCl concentration, and the order of extraction is Zr > Hf ≈ Rf. By considering the order of chloride complexation among these elements, it is suggested that the stability of the TBP complex of Rf tetrachloride is lower than those of Zr and Hf.

Role of cleavage by separase of the Rec8 kleisin subunit of cohesin during mammalian meiosis I

Proteolytic activity of separase is required for chiasma resolution during meiosis I in mouse oocytes. Rec8, the meiosis-specific alpha-kleisin subunit of cohesin, is a key target of separase in yeast. Is the equivalent protein also a target in mammals? We show here that separase cleaves mouse Rec8 at three positions in vitro but only when the latter is hyper-phosphorylated. Expression of a Rec8 variant (Rec8-N) that cannot be cleaved in vitro at these sites causes sterility in male mice. Their seminiferous tubules lack a normal complement of 2 C secondary spermatocytes and 1 C spermatids and contain instead a high proportion of cells with enlarged nuclei. Chromosome spreads reveal that Rec8-N expression has no effect in primary spermatocytes but produces secondary spermatocytes and spermatids with a 4 C DNA content, suggesting that the first and possibly also the second meiotic division is abolished. Expression of Rec8-N in oocytes causes chromosome segregation to be asynchronous and delays its completion by 2-3 hours during anaphase I, probably due to inefficient proteolysis of Rec8-N by separase. Despite this effect, chromosome segregation must be quite accurate as Rec8-N does not greatly reduce female fertility. Our data is consistent with the notion that Rec8 cleavage is important and probably crucial for the resolution of chiasmata in males and females.

Molecular characterization and histochemical demonstration of salmon olfactory marker protein in the olfactory epithelium of lacustrine sockeye salmon (Oncorhynchus nerka)

Despite the importance of olfactory receptor neurons (ORNs) for homing migration, the expression of olfactory marker protein (OMP) is not well understood in ORNs of Pacific salmon (genus Oncorhynchus). In this study, salmon OMP was characterized in the olfactory epithelia of lacustrine sockeye salmon (O. nerka) by molecular biological and histochemical techniques. Two cDNAs encoding salmon OMP were isolated and sequenced. These cDNAs both contained a coding region encoding 173 amino acid residues, and the molecular mass of the two proteins was calculated to be 19,581.17 and 19,387.11Da, respectively. Both amino acid sequences showed marked homology (90%). The protein and nucleotide sequencing demonstrates the existence of high-level homology between salmon OMPs and those of other teleosts. By in situ hybridization using a digoxigenin-labeled salmon OMP cRNA probe, signals for salmon OMP mRNA were observed preferentially in the perinuclear regions of the ORNs. By immunohistochemistry using a specific antibody to salmon OMP, OMP-immunoreactivities were noted in the cytosol of those neurons. The present study is the first to describe cDNA cloning of OMP in salmon olfactory epithelium, and indicate that OMP is a useful molecular marker for the detection of the ORNs in Pacific salmon.

Identification of proSAAS homologs in lower vertebrates: conservation of hydrophobic helices and convertase-inhibiting sequences

The prohormone convertases (PCs) 1/3 and 2 accomplish the major proteolytic cleavage events in neuroendocrine tissues; each of these convertases has a small associated binding protein that inhibits convertase action in the secretory pathway. The proSAAS protein binds to PC1/3, whereas the 7B2 protein binds to PC2. However, both convertase-binding proteins are more widely expressed than their cognate enzymes, suggesting that they may perform other functions as well. All known mammalian proSAASs are over 85% conserved; thus, identifying functionally important segments has been impossible. Here, we report the first identification of nonmammalian proSAAS molecules, from Xenopus and zebrafish (Danio rerio). Although these two proteins show an overall amino acid sequence identity of only 29 and 30% with mouse proSAAS, two 14-16 residue hydrophobic segments (predicted to form alpha-helices) and two, nine through 11 residue sequences containing basic convertase cleavage sites are highly conserved; therefore, these sequences may be of functional importance. Confidence that these nonmammalian molecules represent authentic proSAAS is supported by the finding that both inhibit mouse PC1/3 with nanomolar inhibition constants; human furin was not inhibited. In vitro, the two proteins were cleaved by PC2 and furin to three or more peptide products. Both zebrafish and Xenopus proSAAS exhibited neural and endocrine distributions, as assessed by in situ and PCR experiments, respectively. In summary, the identification of proSAAS molecules in lower vertebrates provides clues as to functional regions within this widely expressed neuroendocrine protein.

ABO blood type incompatible kidney transplantation without splenectomy prepared with plasma exchange and rituximab

We have designed a protocol for ABO-incompatible kidney transplantations based on preoperative plasmapheresis with a tacrolimus/mycophenolate mofetil/methylprednisolone/basiliximab protocol using low-dose rituximab (200 mg/body) instead of splenectomy to prevent antibody-mediated acute rejection. Eight patients successfully received transplants with this protocol. The titers of anti-A and -B antibodies as well as the number of CD20(+) cells were readily maintained at a low level posttransplantation. There were no side effects. All patients have renal transplant function with a follow-up of 1-34 months.

SOLVING THE INTERIOR PROBLEM OF COMPUTED TOMOGRAPHY USING A PRIORI KNOWLEDGE

The case of incomplete tomographic data for a compactly supported attenuation function is studied. When the attenuation function is a priori known in a subregion, we show that a reduced set of measurements is enough to uniquely determine the attenuation function over all the space. Furthermore, we found stability estimates showing that reconstruction can be stable near the region where the attenuation is known. These estimates also suggest that reconstruction stability collapses quickly when approaching the set of points that are viewed under less than 180 degrees. This paper may be seen as a continuation of the work "Truncated Hilbert transform and Image reconstruction from limited tomographic data" that was published in Inverse Problems in 2006. This continuation tackles new cases of incomplete data that could be of interest in applications of computed tomography.