VARIOUS BLANCHING TREATMENTS EFFECT FINAL TEXTURE AND TOTAL FIBER CONTENT OF PEELED PROCESSED ASPARAGUS

The effect of peeling and three different methods of blanching on the texture of white asparagus was studied. Texture was measured in terms of maximum shear force and cutting energy, and as total fiber content. Manual peeling reduced the required cutting force in the middle and basal sections of the spear; fiber content diminished due to the elimination of the outer, most heavily lignified, layers of stalk. Results suggest that blanching by progressive immersion in hot water may be a feasible method of maintaining uniformity in asparagus texture. Blanching in hot water vapor seems to provide for less tough spears.     

Microglia-precursor cell interactions in health and in pathology

Until recently, microglia were mainly known as the resident phagocytes of the brain, i.e. the ‘immunological warriors’ of the brain. However, extensive knowledge is being accumulated about the functions of microglia beyond immunity. Nowadays, it is well accepted that microglial cells are highly dynamic and responsive, and that they intervene in a dual manner in many developmental processes that shape the central nervous system, including neurogenesis, gliogenesis, spatial patterning, synaptic formation and elimination, and neural circuit establishment and maturation. The differentiation and the pool of precursor cells were also shown to be under microglia regulation via bidirectional communication. In this concise review, I discuss our recent work in microglia-Pax6⁺ cell interactions in one of the circumventricular organs, the pineal gland. An analogy with the rest of the central nervous system is also presented. In addition, I briefly examine mechanisms of interaction between microglia and non-microglial cells in both health and disease. New avenues are also introduced, which may lead us to better comprehend the impact of microglia in physiological and pathological conditions.     

A method to simulate the optical image from far-field scattering numerical data and its application to the total internal reflection microscopy of metallic nanowires

Computational electrodynamics modelling plays an important role in understanding and designing new photonic devices. The results offered by these simulations are usually close-range field distributions or angular power emission plots. We describe a procedure to compute the optical microscopy image from simulated far-field scattering data using three-dimensional discrete Fourier transforms that can be used when the simulation software package do not include proper far-field to optical imaging projection routines. The method is demonstrated comparing simulated images with real images of nanowires obtained with a total internal reflection microscope.     

In vivo identification of intermediate stages of the DNA inversion reaction catalyzed by the Salmonella Hin recombinase

The Hin recombinase catalyzes a site-specific recombination reaction that results in the reversible inversion of a 1-kbp segment of the Salmonella chromosome. The DNA inversion reaction catalyzed by the Salmonella Hin recombinase is a dynamic process proceeding through many intermediate stages, requiring multiple DNA sites and the Fis accessory protein. Biochemical analysis of this reaction has identified intermediate steps in the inversion reaction but has not yet revealed the process by which transition from one step to another occurs. Because transition from one reaction step to another proceeds through interactions between specific amino acids, and between amino acids and DNA bases, it is possible to study these transitions through mutational analysis of the proteins involved. We isolated a large number of mutants in the Hin recombinase that failed to carry out the DNA exchange reaction. We generated genetic tools that allowed the assignment of these mutants to specific transition steps in the recombination reaction. This genetic analysis, combined with further biochemical analysis, allowed us to define contributions by specific amino acids to individual steps in the DNA inversion reaction. Evidence is also presented in support of a model that Fis protein enhances the binding of Hin to the hixR recombination site. These studies identified regions within the Hin recombinase involved in specific transition steps of the reaction and provided new insights into the molecular details of the reaction mechanism.     

Efficacy of lasalocid against murine Pneumocystis carinii pneumonitis

The efficacy of the ionophore lasalocid against Pneumocystis carinii pneumonitis in corticosteroid-immunosuppressed Sprague-Dawley rats was investigated. Lasalocid was effective in the prevention of the pneumonitis in a dose-dependent manner. At dosages of 0, 5, 10, and 20 mg/kg/day, P. carinii infection rates were 92, 60, 20, and 0%, respectively, during dexamethasone immunosuppression. Also, lasalocid compared favorably with other drugs known to have anti-P. carinii activity, including trimethoprim-sulfamethoxazole, atovaquone, and dapsone-trimethoprim.     

Further study of hantavirus circulation in the Russian Federation

Lung specimens of 1514 small mammals of 35 species captured in 1991-1995 at 9 territories of Russia were tested in ELISA for virus antigens of hemorrhagic fever with the renal syndrome (HFRS). The antigens were detected in lung specimens of Clethrionomys glareolus, Microtus arvalis, Microtus gregalis, Microtus fortis, Arvicola terrestris, Apodemus agrarius, Micromys minutus, and Sorex sp., well known as Hantavirus reservoirs, captured in the Vologda, Yaroslavl, Saratov, Astrakhan, and Chita regions. Infection of Microtus maximoviczii revealed in the Chita region was first found in China. Previously there were no reports about the circulation of hantaviruses in this region. Our study added one more host to the list of HFRS virus hosts: Meliones tamariscinus.     

BACTERIOLOGICAL ANALYSIS OF FROZEN SHRIMPS. 1. Total Plate Count-Coliforms and Enterococci in Precooked Frozen Chilean Shrimp

SUMMARY– 392 samples of precooked frozen shrimps from 2 Chilean industries (A and B) were analyzed for total bacterial count, conforms and enterococci throughout a period of 8 months. 1-lb samples of breaded shrimp were received directly from the manufacturers after a freezing period of 10 days at —18δC. Total bacterial count ranged from 10⁴ to 10⁵ organisms perg. Conforms were absent in 65% of the samples from A, and in 40% of those from 8; 89.6% of the samples from A and 50.1% of those from B were bacteriologically acceptable considering a limit of not more than 50 coliforms per g. 98% of the frozen shrimp samples belonging to A contained enterococci, as did 66% of the samples from B. Smaller percentages (17% for A and 54% for B) of acceptable samples are obtained from both industries when 100 enterococci per g is considered as the limit. During the period of observation some sanitary measures were adopted and subsequent coliform counts improved. In plant A working conditions are better and the understanding of bacteriological grounds for the proper handling of food materials has led to the elaboration of a product of consistently better quality. Enterococci counts are in contradiction with coliform counts, since the low-level coliform samples are rejected on the basis of their enterococcal content. In plant B there is a better correlation between coliform and enterococcal counts. Though not investigated, this may be related to the precooking system employed: steaming in an enclosed conveyor in A versus immersion in boiling sea-water in B.     

Dihydrocapsaicin Oxidation by Capsicum annuum (var. annuum) Peroxidase

Oxidation of dihydrocapsaicin (8-methyl-N-vanillyl-6-nonanamide) by peroxidase (EC 1.11.1.7) from Capsicum annuum var. annuum fruits yielded one absorbent oxidation product with E₂₆₂= 4.7 10³ M^?1 cm^?1. Dependence of oxidation rate on dihydrocapsaicin and H₂O₂ concentrations revealed Michaelis-Menten type kinetics with inhibition at high substrate concentrations and optimal pH near 6.0. Dihydrocapsaicin was oxidized by pepper peroxidase, and participation of peroxidase in capsaicinoid metabolism of pepper fruits should be taken into account.