Group II Intron-Anchored Gene Deletion in Clostridium

Clostridium plays an important role in commercial and medical use, for which targeted gene deletion is difficult. We proposed an intron-anchored gene deletion approach for Clostridium, which combines the advantage of the group II intron “ClosTron” system and homologous recombination. In this approach, an intron carrying a fragment homologous to upstream or downstream of the target site was first inserted into the genome by retrotransposition, followed by homologous recombination, resulting in gene deletion. A functional unknown operon CAC1493–1494 located in the chromosome, and an operon ctfAB located in the megaplasmid of C. acetobutylicum DSM1731 were successfully deleted by using this approach, without leaving antibiotic marker in the genome. We therefore propose this approach can be used for targeted gene deletion in Clostridium. This approach might also be applicable for gene deletion in other bacterial species if group II intron retrotransposition system is established

Non-allergic rhinitis: a case report and review

Rhinitis is characterized by rhinorrhea, sneezing, nasal congestion, nasal itch and/or postnasal drip. Often the first step in arriving at a diagnosis is to exclude or diagnose sensitivity to inhalant allergens. Non-allergic rhinitis (NAR) comprises multiple distinct conditions that may even co-exist with allergic rhinitis (AR). They may differ in their presentation and treatment. As well, the pathogenesis of NAR is not clearly elucidated and likely varied. There are many conditions that can have similar presentations to NAR or AR, including nasal polyps, anatomical/mechanical factors, autoimmune diseases, metabolic conditions, genetic conditions and immunodeficiency. Here we present a case of a rare condition initially diagnosed and treated as typical allergic rhinitis vs. vasomotor rhinitis, but found to be something much more serious. This case illustrates the importance of maintaining an appropriate differential diagnosis for a complaint routinely seen as mundane. The case presentation is followed by a review of the potential causes and pathogenesis of NAR

Mucoceles gigantes: visão neurocirúrgica. Relato de dois casos Giant mucoceles: neurosurgical view. Report of two cases

São apresentados dois casos de mucocele gigante do seio frontal submetidos a tratamento cirúrgico. A manifestação clínica foi cefaléia de evolução prolongada, associada com protrusão unilateral do globo ocular de curta duração. Em ambos os casos foi realizada craniotomia frontal com remoção completa da lesão, reparação do soalho frontal com retalho pediculado de gálea e cranialização do seio frontal. No segundo caso, uma abordagem endoscópica intranasal foi combinada à abordagem externa no mesmo ato cirúrgico. Alguns aspectos abordando a etiologia, associação com outras afecções e tratamento cirúrgico são discutidos.<br>Two patients harboring giant frontal mucoceles are reported. In both cases complaints of chronic headaches and progressive unilateral proptosis were preponderant. Surgical treatment included a frontal craniotomy with excision of the lesion, skull base reinforcement with pedicled galea and wide opening of the frontal sinuses. In the second case an intranasal endoscopic approach was combined with craniotomy at the same surgical operative time. Some aspects regarding etiology, association with other diseases and some surgical aspects are discussed

Butanol as a drop-in fuel: a perspective on production methods and current status

The rising fossil fuel prices as well as negative climatic conditions caused by fossil fuel emissions have prompted technologists and scientists to develop alternative value-added fuels. These fuels can be produced from renewable bio-based materials and have less negative impacts on the environment. Much attention has been drawn to advanced fuels such as bio-based butanol, which is considered a promising fuel compared to ethanol. Its properties such as low volatility, less ignition problems and high inter-solubility make it an ideal drop-in fuel for conventional vehicles. This type of fuel can be utilised either in pure or blended form with petrol or diesel. Conventionally, butanol is produced through the acetone–butanol–ethanol (ABE) process using mainly Clostridium species to ferment sugars obtained from biomass. This method makes use of sustainable/cost-effective bacteria that are easily accessible. Alternatively, butanol can be directly produced from bio-based ethanol through aldol condensation using metal oxides/hydroxyapatite catalysts. Catalyst synthesis involves short reaction times, but high reaction temperatures. This chapter highlights the use of butanol as a fuel, reviews different methods employed and discusses current status and potential for future prospect