Does the neuropeptide somatostatin have therapeutic potential against schistosomiasis?

The neuropeptide hormone somatostatin is used to treat bleeding oesophageal varices and to reduce portal pressure, and can prevent progression to severe fibrosis in chronic liver disease. We believe that somatostatin can also have therapeutic potential against schistosomiasis, based on recent observations that severe morbidity symptoms are associated with low levels of host somatostatin in patients infected with Schistosoma mansoni. The administration of exogenous doses of this neuropeptide could therefore alleviate the pathology caused by schistosomiasis.     

Does biopolymers composition in seeds contribute to the flax resistance against the Fusarium infection?

Over the last decades, the cultivation of fibrous flax declined heavily. There are number of reasons for that fact; one of them is flax susceptibility to the pathogen infection. Damages caused mainly by fungi from genus Fusarium lead to the significant losses when cultivating flax, which in turn discourage farmers to grow flax. Therefore, to launch the new products from flax with attractive properties there is a need to obtain new flax varieties with increased resistance to pathogens. In order to obtain the better quality of flax fiber, we previously generated flax with reduced pectin or lignin level (cell wall polymers). The modifications altered also plants' resistance to the Fusarium infection. Undoubtedly, the plant defense system is complex, however, in this article we aimed to investigate the composition of modified flax seeds and to correlate it with the observed changes in the flax resistance to the pathogen attack. In particular, we evaluated the content and composition of carbohydrates (cell wall polymers: pectin, cellulose, hemicelluloses and mucilage), and phenylpropanoid compounds (lignin, lignans, phenolics). From the obtained results we concluded that the observed changes in the vulnerability to pathogens putatively correlate with the antioxidant potential of phenylpropanoids accumulated in seeds, seco‐isolariciresinol and coumaric acid diglycosides in particular, and with pectin level as a carbon source for pathogens. Surprisingly, relatively less important for the resistance was the physical barrier, including lignin and cellulose amount and cellulose structure. Certainly, the hypothesis should be verified on a larger number of genotypes. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:992–1004, 2014     

Does vitamin D protect against DNA damage?

Vitamin D is a secosteroid best known for its role in maintaining bone and muscle health. Adequate levels of vitamin D may also be beneficial in maintaining DNA integrity. This role of vitamin D can be divided into a primary function that prevents damage from DNA and a secondary function that regulates the growth rate of cells. The potential for vitamin D to reduce oxidative damage to DNA in a human has been suggested by clinical trial where vitamin D supplementation reduced 8-hydroxy-2'-deoxyguanosine, a marker of oxidative damage, in colorectal epithelial crypt cells. Studies in animal models and in different cell types have also shown marked reduction in oxidative stress damage and chromosomal aberrations, prevention of telomere shortening and inhibition of telomerase activity following treatment with vitamin D. The secondary function of vitamin D in preventing DNA damage includes regulation of the poly-ADP-ribose polymerase activity in the DNA damage response pathway involved in the detection of DNA lesions. It is also able to regulate the cell cycle to prevent the propagation of damaged DNA, and to regulate apoptosis to promote cell death. Vitamin D may contribute to prevention of human colorectal cancer, though there is little evidence to suggest that prevention of DNA damage mediates this effect, if real. Very limited human data mean that the intake of vitamin D required to minimise DNA damage remains uncertain.     

Does the skeleton of a sponge provide a defense against predatory reef fish?

Sponge tissue often contains two structural components in high concentrations: spicules of silica, and refractory fibers of protein (spongin). Some terrestrial plants contain analogous structures, siliceous inclusions and refractory lignins, that have been demonstrated to deter herbivory. We performed feeding experiments with predatory reef fish to assess the deterrent properties of the structural components of three common Caribbean demosponges, Agelas clathrodes, Ectyoplasia ferox, and Xestospongia muta. The concentrations of spicules and spongin in the tissues varied widely between the three species, but when assayed at their natural volumetric concentrations, neither spicules (all three species assayed) nor the intact spiculated spongin skeleton (A. clathrodes and X. muta assayed) deterred feeding by reef fish in aquarium or field assays using prepared foods of a nutritional quality similar to, or higher than, that of sponge tissue. Spicules deterred feeding in aquarium assays when incorporated into prepared foods of a nutritional quality lower than that of sponge tissue (15–19 times less protein), but spiculated spongin skeleton was still palatable, even in prepared foods devoid of measurable protein, and even though spicules embedded in spongin were oriented in their natural conformation. Based on comparisons of the nutritional qualities of the tissues of the three sponge species and of the prepared foods, sponge tissue would have to be much lower in food value (5 times less protein or lower) for spicules to provide an effective defense, and spicules in combination with the spongin skeleton would be unlikely to provide an effective defense regardless of the nutritional quality of the tissue. Unlike terrestrial plants, marine sponges may use silica and refractory fibers solely for structural purposes.     

How does the toad's visual system discriminate different worm-like stimuli?

Behavioral experiments show that toads exhibit stimulus- and locus-specific habituation. Different worm-like stimuli that toads can discriminate at a certain visual location form a dishabituation hierarchy. What is the neural mechanism which underlies these behaviors? This paper proposes that the toad discriminates visual objects based on temporal responses, and that discrimination is reflected in different average neuronal firing rates at some higher visual center, hypothetically anterior thalamus. This theory is developed through a large-scale neural simulation which includes retina, tectum and anterior thalamus. The neural model based on this theory predicts that retinal R2 cells play a primary role in the discrimination via tectal small pear cells (SP) and R3 cells refine the feature analysis by inhibition. The simulation demonstrates that the retinal response to the trailing edge of a stimulus is as crucial for pattern discrimination as the response to the leading edge. The new dishabituation hierarchies predicted by this model by reversing contrast and shrinking stimulus size need to be tested experimentally.     

Does phenobarbital protect against trimethyltin-induced neuropathology of limbic structures?

Because of the similarity in the pattern of limbic sites damaged by both compounds, it has been suggested that trimethyltin (TMT) may be an excitotoxin like kainic acid (KA). KA produces seizures which eventually result in neuronal damage similar to that found in epilepsy. Anticonvulsants reduce both the seizures and pathology associated with KA. Because TMT may also produce seizures, we undertook to determine whether or not some of the TMT-induced limbic neuropathology could result from seizure activity. To do this, a single dose of TMT chloride (either 7.5 or 15 mg/kg) was given per os to rats, and then phenobarbital (30 mg/kg) was administered subcutaneously in repeated doses. Treatment with phenobarbital did not prevent pathologic changes in the hippocampus, dentate gyrus, and pyriform or prepyriform cortex. Since phenobarbital did not protect against TMT-induced neuronal damage, as it has been reported by others to protect against KA-induced damage, the present findings suggest that these two toxicants probably produce hippocampal pathology via different mechanisms and that the TMT-induced pathologic changes do not require sustained electrical seizure activity.     

Does sex (female versus male) influence the impact of class attendance on examination performance?

The "conventional wisdom" is that grades are related to class attendance, i.e., students who attend classes more frequently obtain better grades and class attendance dramatically contributes to enhanced learning. However, the influence of sex (female vs. male) on this relationship is understudied. Furthermore, there have been several studies examining the impact of attendance on course grades that challenge the conventional wisdom. To address these issues, we determined the effect of class attendance on examination scores for female and male students enrolled in our undergraduate exercise physiology class of 51 students (20 female students and 31 male students). The experiment was designed not to interfere with the normal conduct of the course. Attendance was recorded in each class, and, although regular attendance was encouraged, it was not required and did not factor into the final grades. The final grade reflected the average days of attendance for female students only. Specifically, female students earning a grade above the class average attended 89 ± 4% of the classes; however, female students earning a grade below the class average attended only 64 ± 6% of the classes. In sharp contrast, there was no difference in the number of classes attended for male students earning grades above or below the class average (84 ± 3% vs. 79 ± 5%). Accordingly, some male students were absent frequently but scored above the class average, whereas other male students attended many classes but scored below the class average. Thus, the influence of regular attendance on examination performance is more important for female students than male students.     

Does hydatid disease have protective effects against lung cancer?

We hypothesized that solid tumors rarely occur in patients with hydatid disease. We obtained the serum of 14 patients diagnosed with hydatid disease, the serum of 10 patients who did not have a history of hydatid disease, and the hydatid cyst fluid from six patients. These sera and fluid samples were added at different concentrations to NCI-H209/An1 human lung small cell carcinoma cells and L929 mouse fibroblasts as a control group. Sera of patients with hydatid diseases had cytotoxic effects on NCI-H209/An1 cells, but they did not have cytotoxic effects on fibroblast cells. Sera from healthy subjects did not have a cytotoxic effect on the tumor cell line or control fibroblasts. Cyst fluid, also, did not have toxic effects on the NCI-H209/An1 cell line, but was toxic to fibroblasts up to a 1:32 dilution. Sera from patients with hydatid disease had cytotoxic effects on human small cell lung cancer cells in vitro.     

Where is the silver lining? Anxious doctors ask.

When Nova Scotia elected a Liberal government in September 1993, a wave of optimism washed over the province''s medical community. One of their own, Dr. John Savage, was now premier, and another, Dr. Ron Stewart, was minister of health. However, anticipation soon turned to anger as Stewart took aim at physician fees and hospital costs to help reduce the province''s health care budget by $62 million. Last November, relations between him and the Medical Society of Nova Scotia (MSNS) hit bottom. In an uncharacteristically political move, the society launched an ad campaign featuring slogans such as "Death by 1000 cuts" and "Uncle Sam want me. Ron Stewart doesn''t." Four months later, the health department and the MSNS called a truce, with an agreement that many physicians consider a positive step. Today the province and its doctors are speaking again, and the medical society is working hard to help define physicians'' roles in a new, regionalized health care system. But has the mood of doctors really improved? Last spring, CMAJ interviewed a cross section of Nova Scotia physicians to find out.     

Does the Bicoid gradient matter?

The generation and interpretation of positional information are key processes in developmental systems. In this issue, Chen et?al. report discoveries made in the Drosophila embryo that give new insights into how positional information can be produced by patterning gradients.