Biodiesel production—current state of the art and challenges

Biodiesel is a clean-burning fuel produced from grease, vegetable oils, or animal fats. Biodiesel is produced by transesterification of oils with short-chain alcohols or by the esterification of fatty acids. The transesterification reaction consists of transforming triglycerides into fatty acid alkyl esters, in the presence of an alcohol, such as methanol or ethanol, and a catalyst, such as an alkali or acid, with glycerol as a byproduct. Because of diminishing petroleum reserves and the deleterious environmental consequences of exhaust gases from petroleum diesel, biodiesel has attracted attention during the past few years as a renewable and environmentally friendly fuel. Since biodiesel is made entirely from vegetable oil or animal fats, it is renewable and biodegradable. The majority of biodiesel today is produced by alkali-catalyzed transesterification with methanol, which results in a relatively short reaction time. However, the vegetable oil and alcohol must be substantially anhydrous and have a low free fatty acid content, because the presence of water or free fatty acid or both promotes soap formation. In this article, we examine different biodiesel sources (edible and nonedible), virgin oil versus waste oil, algae-based biodiesel that is gaining increasing importance, role of different catalysts including enzyme catalysts, and the current state-of-the-art in biodiesel production. JIMB 2008: BioEnergy—special issue.     

α/β-Peptide foldamers: state of the art

Interplay between proteins, nucleic acids, carbohydrates and/or lipids is involved in almost every process in life on earth. As a consequence, a wide range of diseases results from abnormal interactions of such biomolecules. The main motivation of foldamer science is the development of scaffolds that are capable of adopting defined structures, mimicking parts of biological protagonists in their function. Among the most fundamental interactions in living beings are those between proteins, the so called protein–protein interactions (PPIs). Therefore, peptidic foldamers bear the promise to be an important tool for the inhibition of PPIs, as they are structurally most similar to the original proteins. The great number of possible permutations given by the combination of proteinogenic α-amino acid residues along with β-amino acids opens the door for a larger pool of accessible structures with potential applications. Despite the increasing amount of new secondary structure motifs, only few examples for tertiary and quaternary structure design, as well as inhibition of PPIs, have been realized so far. In this review, we summarize the current knowledge and recent progress made in the field of α/β-peptide foldamers beginning from secondary structure design up to highly sophisticated biological applications, such as protein surface recognition and inhibition of HIV cell entry.     

Perioperative management of pheochromocytoma/paraganglioma: is there a state of the art?

Pheochromocytoma and paraganglioma are rare tumors of sympathetic or parasympathetic origin, presenting with a highly variable clinical picture. Rarity, as well as biological, clinical, and genetic heterogeneity are barriers to initiate prospective studies that help to establish clinical guidelines. The best management of these patients relies on the experience of a multidisciplinary team. The ultimate outcome can benefit from adequate pre-surgical evaluation and treatment as well as an accurate post-surgical follow-up. Long-term follow-up is mandatory in all patients, but is particularly important in specific familial cases such as those with an SDHB mutation where the risks of recurrence are higher. The surgical approach varies depending on tumor size, location, and surgeon's personal attitude and experience. In this paper, we summarize recommendations, based mostly on authors' and other experts' personal experiences, for the best possible management of patients prior, during and after surgery, as well as when pheochromocytoma is diagnosed during pregnancy.     

Mesozoic calcareous nannofossils — state of the art

Calcareous nannofossils originated in the Triassic, radiated in the Jurassic and became a dominant component of the marine biosphere from the earliest Jurassic onward. They can be considered as one of the most important “innovations” of the Mesozoic oceans. Their basic morphology allows the differentiation of three different groups: coccoliths, nannoliths and calcispheres (= calcareous dinocysts). Only coccoliths and nannoliths are discussed in this article in some detail. Coccoliths and nannoliths have contributed greatly in the Interpretation of Mesozoic marine Systems through biostratigraphy and palaeoecology/palaeoceanography. Ever since the late 1960s both coccoliths and nannoliths have proven to be useful and reliable zonal markers for biostratigraphic schemes, allowing detailed zonations for the Jurassic and Cretaceous. Though affected by palaeobiogeographic provincialism, coccoliths and nannoliths have supplied many cosmopolitan biostratigraphic markers. These allow a global correlation of marine sedimentary units both from onshore sections in the classical European and North American areas and pelagic sequences recovered in the course of the DSDP/ODP drilling from the world’s oceans. Thus research on calcareous nannofossils Covers both, regional and global aspects. Research in the last 15 years concentrated on palaeoecological aspects. Apart from dinoflagellates, coccolithophores were the most important primary producers in Mesozoic oceans. As such they heavily relied on autecological factors such as light, nutrients and temperature. Variations in the assemblage composition of these groups may thus be viewed as a key for understanding palaeoecological, palaeoceanographic and palaeoclimatic changes of the past.      

Carotenoids and cardiovascular disease: what research gaps remain?

PURPOSE OF REVIEW: Dietary and blood carotenoids, including alpha-carotene, beta-carotene, lycopene, lutein/zeaxanthin, and beta-cryptoxanthin, have been examined in a number of epidemiological studies in recent years for the risk of cardiovascular disease. This review assimilated the existing and recent literature on carotenoids and cardiovascular disease and considered what research gaps may remain. RECENT FINDINGS: Numerous large cohort studies have been published in largely American men and women that have examined dietary intake or blood levels of total or individual carotenoids with the risk of various cardiovascular endpoints. Overall, early, promising results have grown increasingly inconsistent over time. More recently, studies examining lycopene and lutein/zeaxanthin have offered more promising data on a possible, but not yet established, inverse association with the risk of cardiovascular disease. Recent epidemiological data on beta-cryptoxanthin and cardiovascular disease are lacking. Primary and secondary prevention trials have extensively examined beta-carotene, but not other carotenoids, for the risk of cardiovascular disease as either the primary or secondary endpoint with largely null results. More recent studies have focused on individual carotenoids in relation to cardiovascular disease and require a more careful evaluation of potential mechanisms of effect. SUMMARY: The promise of early epidemiological studies on carotenoids and cardiovascular disease paved the way to largely disappointing results from several large prevention trials of beta-carotene. Emerging recent evidence of potential cardioprotective effects for lycopene and other carotenoids besides beta-carotene in the diet and blood suggest that there is more to be learned in the story of carotenoids and both atherosclerotic progression and clinically manifested cardiovascular disease.     

Invited review: Improving feed efficiency of beef cattle – the current state of the art and future challenges

Improvements in feed efficiency of beef cattle have the potential to increase producer profitability and simultaneously lower the environmental footprint of beef production. Although there are many different approaches to measuring feed efficiency, residual feed intake (RFI) has increasingly become the measure of choice. Defined as the difference between an animal’s actual and predicted feed intake (based on weight and growth), RFI is conceptually independent of growth and body size. In addition, other measurable traits related to energy expenditure such as estimates of body composition can be included in the calculation of RFI to also force independence from these traits. Feed efficiency is a multifactorial and complex trait in beef cattle and inter-animal variation stems from the interaction of many biological processes influenced, in turn, by physiological status and management regimen. Thus, the purpose of this review was to summarise and interpret current published knowledge and provide insight into research areas worthy of further investigation. Indeed, where sufficient suitable reports exist, meta-analyses were conducted in order to mitigate ambiguity between studies in particular. We have identified a paucity of information on the contribution of key biological processes, including appetite regulation, post-ruminal nutrient absorption, and cellular energetics and metabolism to the efficiency of feed utilisation in cattle. In addition, insufficient information exists on the relationship between RFI status and productivity-related traits at pasture, a concept critical to the overall lifecycle of beef production systems. Overall, published data on the effect of RFI status on both terminal and maternal traits, coupled with the moderate repeatability and heritability of the trait, suggest that breeding for improved RFI, as part of a multi-trait selection index, is both possible and cumulative, with benefits evident throughout the production cycle. Although the advent of genomic selection, with associated improved prediction accuracy, will expedite the introgression of elite genetics for feed efficiency within beef cattle populations, there are challenges associated with this approach which may, in the long-term, be overcome by increased international collaborative effort but, in the short term, will not obviate the on-going requirement for accurate measurement of the primary phenotype.     

Stem cells: From embryology to cellular therapy? An appraisal of the present state of art

Abtract A series of publications has dealt in the last years with topics as the isolation, properties and applications of animal stem cells (Weissman 2000. Cell 100: 157–168; Weissman 2002. N. Engl. J. Med. 346: 1567–1579; Lovell-Badge 2001. Nature 414: 88–91; Marshak et al. 2001. Stem Cell Biology. Cold Spring Harbor Laboratory Press, New york; Eridani 2002. J. Roy. Soc. Med. 95: 5–8; Borge and Evers 2003. Cytotechnology 41: 59–68; Sgaramella 2003. Cytotechnology 41: 69–73), however, the bonanza of experimental data recently accumulating have raised such an amount of controversial views and discussions that time perhaps has come for a reassessment of the basic facts in this peculiar area of research and an evaluation of possible, not unrealistic, implications.     

Hereditary hypertriglyceridemic rat: a suitable model of cardiovascular disease and metabolic syndrome?

Hypertriglyceridemia and hypertension seem to be very important cardiovascular risk factors. The Prague hereditary hypertriglyceridemic (hHTG) rat was developed as a model of human hypertriglyceridemia. It was demonstrated that these rats are not obese, they are hypertensive and insulin resistant and they have some disturbances in glucose metabolism. Several QTLs were identified for blood pressure, its particular components (dependent on major vasoactive systems) and plasma triglycerides throughout the genome of hHTG rats by using of F(2) hybrids strategy. It is evident that hHTG rats are a suitable model for the study of metabolic disturbances in relation to blood pressure as well as for the search of genetic determinants of these abnormalities. Numerous abnormalities of blood pressure regulation as well as alterations in the structure and function of cardiovascular apparatus (heart, conduit and resistance arteries) were found in hHTG rats. A special attention was paid to possible changes in the efficiency of various vasoactive systems such as nitric oxide, renin-angiotensin-aldosterone system and sympathetic nervous system, which seem to contribute substantially to cardiovascular and/or metabolic abnormalities observed in Prague hereditary hypertriglyceridemic rats.     

Anaerobic microbial dehalogenation of organohalides — state of the art and remediation strategies

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Searching for allelopathic effects of submerged macrophytes on phytoplankton—state of the art and open questions

Allelopathy, here defined as biochemical interactions between aquatic primary producers, has always been intriguing as a process explaining the dominance of certain plant or algal species over others. Negative chemical interference has been invoked as one of the steering mechanisms behind mutual dominance of either submerged macrophytes or phytoplankton in shallow eutrophic lakes. Yet, despite much effort, convincing evidence for allelopathic interactions in situ is still missing. Also, laboratory approaches often lack reality. Inspired by a series of talks at the Shallow Lakes 2005 meeting in Dalfsen, the Netherlands, we argue that there is circumstantial but strong evidence that allelopathic interference between submerged macrophytes and phytoplankton may indeed exist in aquatic ecosystems despite the problems associated with research in this field. We first discuss experimental approaches combining laboratory and field studies, based on examples presented at this meeting. We then discuss the impact of nutrient status of both producing and target organism and biotic factors such as herbivory or pathogens that might affect allelopathy. Further topics are the potential seasonality of effects and the species-specificity of certain allelochemicals. We conclude with some thoughts why a final proof for allelopathy in situ might remain difficult or even inaccessible in some cases, and why we nevertheless should not abandon this idea.