Calcium transients in single fibers of low-frequency stimulated fast-twitch muscle of rat

Ca²⁺transients were investigated in single fibers isolated from ratextensor digitorum longus muscles exposed to chronic low-frequency stimulation for different time periods up to 10 days. Approximately 2.5-fold increases in resting Ca²⁺ concentration([Ca²⁺]) were observed 2 h after stimulationonset and persisted throughout the stimulation period. The elevated[Ca²⁺] levels were in the range characteristicof slow-twitch fibers from soleus muscle. In addition, we noticed atransitory elevation of the integral[Ca²⁺] per pulse with a maximum (~5-fold)after 1 day. Steep decreases in rate constant of[Ca²⁺] decay could be explained by an immediateimpairment of Ca²⁺ uptake and, with longer stimulationperiods, by an additional loss of cytosolic Ca²⁺ bindingcapacity resulting from a decay in parvalbumin content. A partialrecovery of the rate constant of [Ca²⁺] decayin 10-day stimulated muscle could be explained by an increasing mitochondrial contribution to Ca²⁺ sequestration.

     

Parents’ and Physicians’ Perceptions of Children’s Participation in Decision-making in Paediatric Oncology: A Quantitative Study

The goal is to present how shared decision-making in paediatric oncology occurs from the viewpoints of parents and physicians. Eight Swiss Pediatric Oncology Group centres participated in this prospective study. The sample comprised a parent and physician of the minor patient (<18 years). Surveys were statistically analysed by comparing physicians’ and parents’ perspectives and by evaluating factors associated with children’s actual involvement. Perspectives of ninety-one parents and twenty physicians were obtained for 151 children. Results indicate that for six aspects of information provision examined, parents’ and physicians’ perceptions differed. Moreover, parents felt that the children were more competent to understand diagnosis and prognosis, assessed the disease of the children as worse, and reported higher satisfaction with decision-making on the part of the children. A patient’s age and gender predicted involvement. Older children and girls were more likely to be involved. In the decision-making process, parents held a less active role than they actually wanted. Physicians should take measures to ensure that provided information is understood correctly. Furthermore, they should work towards creating awareness for systematic differences between parents and physicians with respect to the perception of the child, the disease, and shared decision-making.     

Neurogenic-committed human pre-adipocytes express CYP1A isoforms

Stem cell models offer an opportunity both for therapeutic use and for the assessment of alternative in vitro models. Human lipoaspirate is a source of adult stem cells (pre-adipocytes), which are able to differentiate into various phenotypes, such as neurogenic lineage. Here, we analyse the suitability of these in vitro models in screening exogenous compounds, such as environmental pollutants, that may affect adipose cells and neurogenic development. To evaluate neurogenic differentiation, we analysed expression of cholinergic system and acetylcholinesterase immunoreactivity. Heterocyclic derivatives of polycyclic aromatic hydrocarbons (PAHs) are often significant components of environmental contaminants. As they contain inducers of cytochrome P450 1A1 (CYP1A1), we explored the activity of CYP1A1-related enzymes, i.e. 7-ethoxycoumarin- and 7-ethoxyresorufin-O-deethylase (ECOD and EROD) in both cell systems in basal conditions and after exposure to non-cytotoxic doses of β-naphthoflavone (BNF), a well-known PAH-type inducer. Both cell models showed basal and inducible levels of ECOD. Analysis of CYP1A1 protein expression and EROD-related enzyme activity confirmed the inducibility of the CYP1A1 isoform by BNF. These results demonstrate that mesenchymal adult stem cells can constitute innovative models. We therefore propose the use of pre-adipocytes and their neurogenic derivates to evaluate the cytotoxic/biological effects of unintended exposure to contaminants.     

Description of trophic status, hyperautotrophy and dystrophy of a coastal lagoon through a potential oxygen production and consumption index—TOSI: Trophic Oxygen Status Index

Seasonal changes of trophic status of the Sacca di Goro lagoon (northern Italy) are analysed through time series of oxygen metabolism for two stations in which separate measures of planktonic, macroalgal (Ulva rigida), and benthic exchange are available. These component results and their sums (i.e. total ecosystem metabolism) are compared using conventional analyses and an index obtained from oxygen fluxes (Trophic Oxygen Status Index, TOSI). The TOSI is derived from the Benthic Trophic Status Index (BTSI) proposed earlier by Rizzo et al. [Estuaries 19 (1996) 247] and basically represents the net potential metabolism. The index results from the relationship between net maximum productivity (NP), measured at saturating light, and dark respiration (DR). The index was developed to provide a simple portrayal of oxygen processing over time and space for shallow aquatic systems and has two modes: a categorical classification and a graphical representation. The categorical classification of the index from autotrophy to heterotropy provides a rapid assessment of the potential oxygen balance and thus evidences critical situations in the lagoonal metabolism. In the graphical representation of the TOSI, three pieces of information are given: the categorical TOSI, the magnitude of flux for both NP and DR and the time line of the fluxes. Where flushing is slow, the TOSI reflects dissolved oxygen dynamics since the NP:|DR| ratio clearly correlates with both the maximum oxygen concentration (MOC) and the daily quantity of oxygen remaining in the water column (RO). However, TOSI is less well related to MOC and RO in open systems in which oxygen concentrations are dominated by physical factors. The graphical representation of TOSI seems also suitable to represent the degree of intrasystem disturbance that is related to the excess of primary production and changes in oxygen availability. It can also discriminate among different photoautotrophic conditions, including hyperautotrophy, as an abnormal oxygen production with respect to the biomass build up, and dystrophy, as the subsequent abnormal oxygen deficit which causes prolonged anoxia and the onset of anaerobic metabolism. Overall, the index provides a tool for rapid assessment of system metabolism and potentially its consequences.     

Crispolide,an unusual hydroperoxysesquiterpene lactone from Tanacetum vulgare

Crispolide, a hydroperoxysesquiterpene lactone with a modified germacrane skeleton, was isolated from the aerial parts of Tanacetum vulgare var. crispum and from two T. vulgare chemotypes. Its structure, 1β-hydroperoxy-5β-hydroxy-4,14-cyclogermacra-9,11-dien-6,12-olide, was elucidated by spectroscopic data and chemical reactions.