A benign approach to the preparation of freshwater bryozoan statoblasts for scanning electron microscopy (SEM) imaging

Abstract

Several different species of freshwater Bryozoa, belonging to the genera Plumatella, Rumarcanella and Fredericella, were detected within the Northern Mallee Pipeline (NMP) system in Victoria, Australia, that required definitive identification. These organisms produce asexual buds called statoblasts, with valves composed of sclerotised chitin that bear minute micro-ornamentations of considerable taxonomical significance. Imaging and analysis of these distinctive micro-ornamentations using scanning electron microscopy (SEM) is often employed for species identification. Meticulous preparation of statoblast samples is therefore required that necessitates the removal of adhering debris, dehydration and drying—whilst mitigating specimen damage and distortion. This technical note describes an approach whereby each of these three steps have been individually designed to be as benign as possible, using mild detergent/sonication to remove debris, a gradual and gentle dehydration procedure using ethanol, and critical point drying. For the overall process, these methods are chosen to optimise control and to minimise the use of harsh and hazardous chemicals.     

The use of adjunctive GPIIb/IIIa inhibitors in patients with unstable angina/non-Q-wave MI undergoing percutaneous coronary intervention

Glycoprotein IIb/IIIa receptor inhibitors represent a relatively new therapeutic approach in the field of antiplatelet therapy. Following the development of abciximab a number of small molecule GPIIb/IIIa inhibitors have been introduced such as tirofiban and eptifibatide. In this fast-moving field the interventional cardiologist needs a framework to guide decision-making for the individual patient. This review covers the efficacy and safety data from the clinical trials of GPIIb/IIIa inhibitors in the context of patients undergoing percutaneous coronary intervention for unstable angina/non-Q-wave myocardial infarction. There is an increasing body of evidence to support the efficacy of GPIIb/IIIa inhibitors in reducing the risk of adverse ischemic events in high and low risk patients undergoing percutaneous coronary intervention. A number of unresolved efficacy and safety issues remain, including the duration of treatment before and after intervention; whether a reduction in the heparin dose would further decrease the risk of hemorrhage without affecting the periprocedural thrombotic rate in patients undergoing PTCA with adjunctive GPIIb/IIIa inhibitors; and the cost-effectiveness of this therapy. When a thorough analysis of cost-effectiveness has been made, it will be easier to advocate the widespread use of these agents in all patients undergoing coronary intervention.     

Protective role of ETA endothelin receptors during the acute phase of Trypanosoma cruzi infection in rats

Chagas' disease, caused by Trypanosoma cruzi, has an acute phase characterized by blood-circulating trypomastigotes and amastigote proliferation in several cell types, especially muscle cells. In the chronic phase, around 70% of infected people are asymptomatic (latent form). The remainder develop chagasic cardiomyopathy and/or digestive syndromes. There is evidence for aggravation of the chronic cardiac pathology by endothelin-mediated vasoconstriction. Holtzman rats have proven to be a good model for Chagas' disease acute phase and latent chronic phase. Now, we investigate the effects of prolonged treatment with an endothelin ET(A) receptor antagonist, BSF 461314, during the acute phase on parasitemia, coronary flow, tissue parasitism and the inflammatory process. Using isolated heart in Langendorff's preparation, endothelial dysfunction was observed only in non-treated infected animals. Histoquantitative analyses carried out in heart and diaphragm showed higher tissue parasitism and/or inflammatory process in BSF 461314-treated animals. Our data indicate that endothelin ET(A) receptors contribute to the initial mechanisms of parasite control. Impairment of the endothelium-dependent vasodilatation favors hazardous effects. However, blocking endothelin ET(A) receptors can prevent the latter.     

Accumulation of fumonisins B1 and B2 in freshly harvested Brazilian commercial maize at three locations during two nonconsecutive seasons

Fifty-six Brazilian commercial maize cultivars were examined for FB1 and FB2 accumulation after two non-consecutive growing seasons. During the 94/95 growing season 35 cultivars were planted at three locations in the state of S?o Paulo, Brazil. All samples (total of 105) were contaminated (0.10 micro/g-6.58 microg/g FB1 and 0.04 microg/g-2.15 microg/g FB2). During the 97/98 growing season, 8 of the cultivars used during 94/95 and 21 others were replanted at the same locations. All 87 samples were contaminated (1.15 microg/g-43.80 microg/g FB1 and 0.08 microg/g-11.65 microg/g FB2). One cultivar accumulated significantly less fumonisins in all locations during both growing seasons, indicating that some degree of selection may be possible even in climates that favor F. moniliforme (verticillioides) infection of maize. The presence of water surplus in soil from kernel maturity to harvest correlated with concentrations of FB1 in the grain for the 8 cultivars planted during both seasons at three locations. Observed trends indicated that water excesses and deficits from silking to harvest increased fumonisin levels. The difference in the incidence of FB1, FB2, and FB1 + FB2 was significant between growing seasons, planting locations and between cultivars. Neither the level of hybridization, nor the type of endosperm, nor the length of the vegetative cycle showed any effect on the FB1 contamination.     

The Scorpion Toxin Tf2 from Tityus fasciolatus Promotes Nav1.3 Opening

We identified Tf2, the first β-scorpion toxin from the venom of the Brazilian scorpion Tityus fasciolatus. Tf2 is identical to Tb2-II found in Tityus bahiensis. We found that Tf2 selectively activates human (h)Na_v1.3, a neuronal voltage-gated sodium (Na_v) subtype implicated in epilepsy and nociception. Tf2 shifts hNa_v1.3 activation voltage to more negative values, thereby opening the channel at resting membrane potentials. Seven other tested mammalian Na_v channels (Na_v1.1-1.2; Na_v1.4-1.8) expressed in Xenopus oocytes are insensitive upon application of 1 μM Tf2. Therefore, the identification of Tf2 represents a unique addition to the repertoire of animal toxins that can be used to investigate Na_v channel function.     

A high-throughput cloning system for reverse genetics in <Emphasis Type="Italic">Trypanosoma cruzi</Emphasis>

Background  

The three trypanosomatids pathogenic to men, Trypanosoma cruzi, Trypanosoma brucei and Leishmania major, are etiological agents of Chagas disease, African sleeping sickness and cutaneous leishmaniasis, respectively. The complete sequencing of these trypanosomatid genomes represented a breakthrough in the understanding of these organisms. Genome sequencing is a step towards solving the parasite biology puzzle, as there are a high percentage of genes encoding proteins without functional annotation. Also, technical limitations in protein expression in heterologous systems reinforce the evident need for the development of a high-throughput reverse genetics platform. Ideally, such platform would lead to efficient cloning and compatibility with various approaches. Thus, we aimed to construct a highly efficient cloning platform compatible with plasmid vectors that are suitable for various approaches.     

Assessment of fertility protection and ovarian reserve with GnRH antagonist in rats undergoing chemotherapy with cyclophosphamide

Background  

Reproductive function following chemotherapy is of increasing importance given that survival rates are improving. We assessed whether a gonadotropin-releasing hormone antagonist (GnRHant; cetrorelix) could promote ovarian protection against damage due to chemotherapy.     

Disability life expectancy for the elderly, city of Sao Paulo, Brazil, 2000: gender and educational differences

There is evidence that 'health life expectancy' (expected number of years to be lived in health) differs by socioeconomic status. Time spent in health or disability plays a critical role in the use of health care services. The objective of this study was to estimate 'disability life expectancy' by age, gender and education attainment for the elderly of the city of S?o Paulo, Brazil, in the year 2000. Data came from the SABE database, population censuses and mortality statistics (SEADE Foundation). Life expectancy with disability was calculated using Sullivan's method on the basis of the current probability of death and prevalence of disability by educational level. The prevalence of disability increased with age, for both sexes and both levels of educational attainment studied. Men showed a lower prevalence of disability, in general, and persons with lower educational attainment showed a higher prevalence of disability. Regarding life expectancy, women could expect to live longer than men, with and without disability. For both sexes, the percentage of life expectancy lived with disability decreased with increasing educational attainment. With increasing educational attainment, the sex differences in the percentage of remaining years to be lived with disability increased for most ages. Finally, the percentage of remaining years to be lived with disability increased with age for males and females, except for males with high educational attainment between the ages 70-75 and 75-80. The results may serve as a guide for public policies in the country, since health problems faced by older persons, such as disability, are the result of a number of past experiences during their life-times, such as health care, housing conditions, hygiene practices and education. Education influences health behaviours and is related, to some extent, to all these factors. Therefore, improvements in education for the disadvantaged may improve health.     

Altered Activation of Protein Kinase PKR and Enhanced Apoptosis in Dystonia Cells Carrying a Mutation in PKR Activator Protein PACT

PACT is a stress-modulated activator of the interferon-induced double-stranded RNA-activated protein kinase (PKR). Stress-induced phosphorylation of PACT is essential for PACT''s association with PKR leading to PKR activation. PKR activation leads to phosphorylation of translation initiation factor eIF2α inhibition of protein synthesis and apoptosis. A recessively inherited form of early-onset dystonia DYT16 has been recently identified to arise due to a homozygous missense mutation P222L in PACT. To examine if the mutant P222L protein alters the stress-response pathway, we examined the ability of mutant P222L to interact with and activate PKR. Our results indicate that the substitution mutant P222L activates PKR more robustly and for longer duration albeit with slower kinetics in response to the endoplasmic reticulum stress. In addition, the affinity of PACT-PACT and PACT-PKR interactions is enhanced in dystonia patient lymphoblasts, thereby leading to intensified PKR activation and enhanced cellular death. P222L mutation also changes the affinity of PACT-TRBP interaction after cellular stress, thereby offering a mechanism for the delayed PKR activation in response to stress. Our results demonstrate the impact of a dystonia-causing substitution mutation on stress-induced cellular apoptosis.