Bioprotectives and probiotics for dry sausages

The microbial stability of dry sausages is determined by the combination and timing of different factors referred to as the hurdle-concept. However, the hurdles present in dry sausage are not sufficient to prevent the survival of Listeria monocytogenes or enterohemorrhagic Escherichia coli O157:H7. Recently bioprotective lactic acid bacteria, which in addition to the production of antimicrobial lactic acid, have been found to contribute to the safety of the dry sausage by producing antimicrobial peptide, i.e. bacteriocins and other low-molecular-mass compounds. Furthermore, the possibilities to use probotics in dry sausage manufacturing process has been addressed recently. As one possible mode of action for probiotics is the production of antimicrobial compounds, lactic acid bacteria may act as both probiotic and bioprotective culture as well as fermenting agent in meat product, such as dry sausage.     

Low-temperature aerosol flow reactor method for preparation of surface stabilized pharmaceutical nanocarriers

Nanoparticles can be used to improve the delivery of many drugs, especially peptides and proteins. Although several methods are available for polymeric nanoparticle preparation, there are few single-stage processes that produce dry, solid nanoparticles that can be easily re-dispersed in pharmaceutical vehicles. The aerosol flow reactor method is a single-stage process that has been used for the preparation of multicomponent, coated nanoparticles under uniform temperature and gas flow field. However, it is traditionally used with high synthesis temperatures. In the present study, the aerosol flow reactor method was further optimized for processing and surface stabilization of pharmaceutical nanoparticles containing temperature sensitive biomolecules. In the developed method, drug-loaded carrier nanoparticles consisting of a biodegradable polymer (Eudragit L100) and a drug (phenylephrine hydrochloride) were first produced by aerosol droplet drying and subsequently coated in the gas phase. The carrier particles were coated with l-leucine in order to inhibit agglomeration of the nanoparticles in solutions before administration. In the coating process, a side stream of l-leucine vapor was directed into the main aerosol flow containing the drug-loaded carriers. The mixing with the main flow at ambient temperature induced a supersaturation of l-leucine vapor and condensation on the carrier particles. The results demonstrate that solid, hydrodynamically stable drug-loaded polymeric nanoparticles can be produced with a thin l-leucine coating. The low process temperature enables the surface engineering of particles loaded with temperature sensitive drugs or bioactive materials to be utilized for drug delivery purposes.     

Size fractionation of wood extractives, lignin and trace elements in pulp and paper mill wastewater before and after biological treatment

Integrated kraft pulp and paper mill wastewater was characterized before (influent) and after (effluent) the activated sludge process by microfiltration (8, 3, 0.45 and 0.22 μm) and ultrafiltration (100, 50, 30 and 3 kDa) into different size fractions. Wood extractives, lignin, suspended solids and certain trace elements were determined in each fraction. Forty four percent of the resin and fatty acids in the influent (12.8 mg/L) occurred in particles (>0.45 μm), 20% as colloids (0.45 μm-3 kDa) and 36% in the <3 kDa fraction. The corresponding values for sterols (1.5 mg/L) were 5, 46 and 49%. In the effluent, resin and fatty acids (1.45 mg/L) and sterols (0.26 mg/L) were mainly present in the <3 kDa fraction, as well as a small proportion in particles. β-sitosterol was present in particles in the effluent (88 ± 50 μg/L). Lignin in the influent was mainly in the colloidal and <3 kDa fractions, whereas in the effluent it was mainly in the <3 kDa fraction. Thus the decrease of lignin in the biological treatment was concentrated on the colloidal fraction. In the influent, Mn, Zn and Si were mainly present in the <3 kDa fraction, whereas a significant proportion of Fe and Al were found also in the particle and colloidal fractions. In the effluent, Fe and Al were mainly present in the colloidal fraction; in contrast, Mn, Zn and Si were mainly in the <3 kDa fraction. The results indicated that the release of certain compounds and elements into the environment could be significantly decreased or even prevented simply by employing microfiltration as a final treatment step or by enhancing particle removal in the secondary clarifier.     

Two Moldy Day-care Centers: a Follow-up Study of Respiratory Symptoms and Infections

Abstract The aim was to study the respiratory symptoms among children exposed to indoor air molds in a day-care environment in Finland. Two day-care centers with a mold problem and two reference day-care centers were included in the study and the health data of the children were collected with a follow-up study of two periods. A total of 229 children 3-7 years old attended the day-care centers. During the first follow-up period, the children in the two day-care centers with mold problems had a significantly increased risk of sore throat, purulent and non-purulent nasal discharge, nasal congestion, hoarseness and common cold. During the second follow-up period, a significantly increased risk of purulent nasal discharge, nasal congestion, hoarseness and cough was observed. Upper respiratory tract symptoms, at least once during the study period, were more prevalent among the children attending mold-problem day-care centers. The mold-exposed children had such symptoms repeatedly or the symptoms were prolonged. In conclusion, in the mold-problem day-care centers, overall morbidity for respiratory symptoms and for common cold increased in comparison with the reference day-care centers.     

Analysis of airborne actinomycete spores with fluorogenic substrates

The reactions between seven fluorogenic substrates and different groups of enzymes, esterases, lipases, phosphatases, and dehydrogenases, were studied in a search for a new method for the detection of actinomycete spores. Fluorescence measurement was chosen as a fast and sensitive method for microbial analysis. The focus of the research was on the spores of important air contaminants: Streptomyces albus and Thermoactinomyces vulgaris. For the measurement of the enzymatic activity, the chosen fluorogenic substrate was added to a mixture of spores and nutrient media, and the resulting fluorescence was measured with a spectrofluorometer. Fluorogenic substrates were found to show enzymatic activities even for dormant spores. Comparison of the enzymatic activities of dormant spores with those of vegetative cells showed similarity of the enzymatic profiles but higher activity for vegetative cells. The increase of enzymatic activity from dormant spores to vegetative cells was not linear but fluctuating. The largest fluctuations were found after 4 to 5 h of incubation. The enzymatic activities of S. albus were 10 to 50 times lower than those of T. vulgaris, except for the dehydrogenase activity, which was seven times higher. These results indicate that analysis with fluorogenic substrates has the potential for becoming a fast and sensitive method for the enumeration and identification of airborne actinomycete spores.     

Effects of ultrafine and fine particles in urban air on peak expiratory flow among children with asthmatic symptoms

Post-mortem morphological, neuropathological and neurochemical findings are described in a girl, aged 14 months, with the early-infantile form of galactosialidosis. An elevation in non-lipid sialic acid was noted in both the grey and white matter of the brain, whereas the white matter displayed a clear reduction in all the major lipids. Multiple cortical-subcortical infarctions were found in the brain, most probably caused by compromised circulation due to endothelial luminal encroachment. Electron microscopy of cerebral blood vessels revealed major swelling of the endothelium due to prominent cytoplasmic vacuolisation. Multiple cytoplasmic vacuoles containing sparse granular or membranous matter were also seen in neurons and glial cells of the brain and spinal cord. Zebra bodies were found in the Purkinje cells, as well as in the spinal anterior horn cells. Prominent endothelial vacuolisation was noted in the liver and kidneys. The renal vascular encroachment was probably the cause of the arterial hypertension with elevated plasma renin activity in the present case. There were innumerable fine vacuoles in the renal epithelium and in the Kupffer cell of the liver, whereas coarser vacuoles were observed in the hepatocytes. The neuronal ultrastructural findings in the present case bear some resemblance to the few reported cases of late-infantile and adult cases of galactosialidosis. The prominent endothelial vacuolisation and focal cerebrovascular lesions, that have not previously been described in galactosialidosis, may be features specific to the rapidly progressive early-infantile form.     

Mathematical models of plant-soil interaction

In this paper, we set out to illustrate and discuss how mathematical modelling could and should be applied to aid our understanding of plants and, in particular, plant-soil interactions. Our aim is to persuade members of both the biological and mathematical communities of the need to collaborate in developing quantitative mechanistic models. We believe that such models will lead to a more profound understanding of the fundamental science of plants and may help us with managing real-world problems such as food shortages and global warming. We start the paper by reviewing mathematical models that have been developed to describe nutrient and water uptake by a single root. We discuss briefly the mathematical techniques involved in analysing these models and present some of the analytical results of these models. Then, we describe how the information gained from the single-root scale models can be translated to root system and field scales. We discuss the advantages and disadvantages of different mathematical approaches and make a case that mechanistic rather than phenomenological models will in the end be more trustworthy. We also discuss the need for a considerable amount of effort on the fundamental mathematics of upscaling and homogenization methods specialized for branched networks such as roots. Finally, we discuss different future avenues of research and how we believe these should be approached so that in the long term it will be possible to develop a valid, quantitative whole-plant model.     

Fully microfabricated and integrated SU-8-based capillary electrophoresis-electrospray ionization microchips for mass spectrometry

We present a fully microfabricated and monolithically integrated capillary electrophoresis (CE)-electrospray ionization (ESI) chip for coupling with high-throughput mass spectrometric (MS) analysis. The chips are fabricated fully of a negative photoresist SU-8 by a standard lithographic process which enables straightforward batch fabrication of multiple chips with precisely controlled dimensions and, thus, reproducible analytical performance from chip to chip. As the coaxial sheath flow interface is patterned as an integral part of the SU-8 chip, the fluidic design is dead-volume-free. No significant peak broadening occurs so that very narrow peak widths (down to 2-3 s) are obtained. The sheath flow interface also enables comprehensive optimization of both the CE and the ESI conditions separately so that the same chip design is adaptable to diverse analytical conditions. Plate numbers of the order of 105 m-1 and good resolution are routinely reached for small molecules and peptides within a 2 cm separation length and a typical cycle time of only 30-90 s per sample. In addition, a limit of detection of 100 nM corresponding to a total amount of only 4.5 amol (per injection volume of 45 pL) and excellent quantitative linearity (R2 = 0.9999; 100 nM to 100 microM) were obtained in small-molecule analysis using verapamil as a test compound. The quantitative repeatability was proven good (8.5-21.4% relative standard deviation, peak area) also for the other drug substances and peptides tested.     

Streptomycetes in house dust: associations with housing characteristics and endotoxin

In addition to mold, indoor bioaerosols also contain bacterial components that may have implications for human health. Endotoxin is a cell wall component in Gram-negative bacteria present at varying levels indoors that has been found to have respiratory health implications. Streptomyces is a large genus of Gram-positive bacteria, and some species have been shown to produce inflammatory reactions in vitro and in vivo. The aim of this study was to determine predictors of streptomycetes levels in house dust and to compare the variation in streptomycetes levels with that in endotoxin levels. Dust was collected by floor vacuuming from 178 homes in the Cincinnati metropolitan area. Streptomycetes levels were measured by quantitative PCR, and endotoxin was assayed by the Limulus amebocyte lysate method. Associations between home characteristics and bacterial contaminants, expressed as concentration and load, were investigated through multiple regression analyses. The presence of two or more dogs was a strong predictor of both streptomycetes and endotoxin levels. Season of dust collection and levels of outdoor molds were predictors of streptomycetes but not endotoxin levels. In contrast, number of inhabitants was a significant predictor of endotoxin load only. Neither streptomycetes nor endotoxin levels were associated with metrics of moisture damage.