Tetracyclines inhibit microglial activation and are neuroprotective in global brain ischemia

Ischemic stroke is the most common life-threatening neurological disease and has limited therapeutic options. One component of ischemic neuronal death is inflammation. Here we show that doxycycline and minocycline, which are broad-spectrum antibiotics and have antiinflammatory effects independent of their antimicrobial activity, protect hippocampal neurons against global ischemia in gerbils. Minocycline increased the survival of CA1 pyramidal neurons from 10.5% to 77% when the treatment was started 12 h before ischemia and to 71% when the treatment was started 30 min after ischemia. The survival with corresponding pre- and posttreatment with doxycycline was 57% and 47%, respectively. Minocycline prevented completely the ischemia-induced activation of microglia and the appearance of NADPH-diaphorase reactive cells, but did not affect induction of glial acidic fibrillary protein, a marker of astrogliosis. Minocycline treatment for 4 days resulted in a 70% reduction in mRNA induction of interleukin-1beta-converting enzyme, a caspase that is induced in microglia after ischemia. Likewise, expression of inducible nitric oxide synthase mRNA was attenuated by 30% in minocycline-treated animals. Our results suggest that lipid-soluble tetracyclines, doxycycline and minocycline, inhibit inflammation and are neuroprotective against ischemic stroke, even when administered after the insult. Tetracycline derivatives may have a potential use also as antiischemic compounds in humans.     

Determination of fiber orientation in Norway spruce using X-ray diffraction and laser scattering

Spiral grain reduces the quality of timber since it causes twisting during drying and reduces the mechanical strength of wood products. The orientation of wood fibers in Norway spruce as a function of the distance from the pith was studied using both x-ray diffraction and light scattering. In radial-longitudinal plane upper tips of fibers were tilted towards the pith and the tilt angle increased gradually towards the bark in most of the samples. Periodic oscillations in the spiral grain angle were observed. Increased growth rate was found to increase the amplitude of this oscillation. There was no clear correlation between the angles determining the fiber orientation and other parameters like the lumen diameter, the cell wall thickness, the density of the sample, the fiber length, the circularity index of the cell lumen, or the mean microfibril angle. However, fiber orientation in tangential-longitudinal plane varied more in broad annual rings than in narrow annual rings.     

Mechanical α-relaxations and stickiness of milk solids/maltodextrin systems around glass transition

BACKGROUND: Stickiness correlates with changes in mechanical α‐relaxation properties and often results from glass transition and plasticisation of amorphous food components. In this study, milk solids with maltodextrins with different dextrose equivalents (DE9 and DE17) were analysed for glass transition (T_g), α‐relaxation (T_α) and sticky point (SPT) temperatures using differential scanning calorimetry, dynamic mechanical analysis and a sticky point test respectively. RESULTS: At the same maltodextrin contents, T_g and T_α were lower for milk solids with the higher‐DE maltodextrin. Increasing maltodextrin contents gave T_g, T_α and SPT at higher temperatures, and the magnitudes of α‐relaxations with high maltodextrin (DE9 and DE17) contents were less pronounced. CONCLUSION: Stickiness was governed by glass transition and affected by skim milk/maltodextrin composition. Stickiness was reduced with increasing maltodextrin content as a result of maltodextrin miscibility with skim milk solids, particularly lactose, which changed the relaxation behaviour above the glass transition. The mixes of milk solids with low‐DE maltodextrin may show improved dehydration characteristics and powder stability resulting from increased T_g, T_α and SPT. Copyright © 2011 Society of Chemical Industry     

Porosity and Water Activity Effects on Stability of Crystalline β‐Carotene in Freeze‐Dried Solids

Abstract: Stability of entrapped crystalline β‐carotene as affected by water activity, solids microstructure, and composition of freeze‐dried systems was investigated. Aliquots (1000 mm³, 20% w/w solids) of solutions of maltodextrins of various dextrose equivalents (M040: DE6, M100: DE11, and M250: DE25.5), M100‐sugars (1:1 glucose, fructose and sucrose), and agar for gelation with dispersed β‐carotene were frozen at ?20, ?40, or ?80 °C and freeze‐dried. Glass transition and α‐relaxation temperatures were determined with differential scanning calorimetry and dynamic mechanical analysis, respectively. β‐Carotene contents were monitored spectrophotometrically. In the glassy solids, pore microstructure had a major effect on β‐carotene stability. Small pores with thin walls and large surface area allowed β‐carotene exposure to oxygen which led to a higher loss, whereas structural collapse enhanced stability of β‐carotene by decreasing exposure to oxygen. As water plasticized matrices, an increase in molecular mobility in the matrix enhanced β‐carotene degradation. Stability of dispersed β‐carotene was highest at around 0.2 a_w, but decreasing structural relaxation times above the glass transition correlated well with the rate of β‐carotene degradation at higher a_w. Microstructure, a_w, and component mobility are important factors in the control of stability of β‐carotene in freeze‐dried solids Practical Application: β‐Carotene expresses various nutritional benefits; however, it is sensitive to oxygen and the degradation contributes to loss of nutritional values as well as product color. To increase stability of β‐carotene in freeze‐dried foods, the amount of oxygen penetration need to be limited. The modification of freeze‐dried food structures, for example, porosity and structural collapse, components, and humidity effectively enhance the stability of dispersed β‐carotene in freeze‐dried solids.     

Daily variability of Listeria contamination patterns in a cold-smoked salmon processing operation

An understanding of Listeria transmission and contamination patterns in processing environments of ready-to-eat foods is critical for improving control of Listeria monocytogenes. A cold-smoked fish processing operation was the site used to study variability in Listeria contamination in a processing environment associated with a ready-to-eat food product throughout one production week (five consecutive days). Intensive testing was conducted on finished products and environmental samples collected at the beginning, middle, and end of each working day. A total of 20 finished products and 22 to 36 environmental samples were collected at each sampling time, and an additional 12 environmental samples were collected on days 4 and 5. Overall, a total of 782 samples, 300 finished products and 482 environmental samples, were tested. All samples were collected from processing steps after smoking, including skinning, trimming, slicing, staging, and packing. A total of 28 finished and 57 environmental samples (9.3 and 11.8%, respectively) were positive for Listeria spp. (including 1 and 5 samples positive for L. monocytogenes, respectively). DNA sequencing of the sigB gene allowed differentiation of eight Listeria subtypes. Listeria prevalence varied significantly between days, and a high prevalence in both environmental samples and finished products on day 3 was likely associated with a point source contamination event by a single Listeria welshimeri subtype. There were no consistent differences in Listeria prevalence among samples collected from the beginning, middle, and end of the production day, but subtype data often revealed unique contamination patterns for samples collected at different times of a given day. Listeria contamination patterns and prevalences were highly variable between days and within a given day. These findings indicate that chance events play an important role in the contamination of finished products, thus complicating efforts to define Listeria transmission patterns in processing environments associated with ready-to-eat foods.