The binding of monoribosomes, oligoribosomes and polyribosomes to reticular membranes from rat liver.

Proteoglycans from pig laryngeal cartilage prepared by dissociative extraction in guanidine hydrochloride were studied in dilute solution by light-scattering and ultracentrifugation. In buffered 150mM-NaCl, pH7.4, the proteoglycan particle weights were about 5x10(6) daltons, but at 100mM-, 200mM- and 300mM-NaCl particle weights of 2.5x10(6)--3.0x10(6) daltons were observed. These results, together with corroborative evidence from sedimentation-velocity experiments, were interpreted in terms of proteoglycans self-associating at physiological ionic strength. The data were examined by using a proteoglycan monomer-dimer model. Proteoglycan preparations that had thiol groups partially carboxymethylated gave particle weights of 3.2x10(6)--3.5x10(6) daltons in 150mM-NaCl, which suggested that carboxymethylation inhibited multimerization and hence that the protein core is implicated in the binding site. Further studies showed that the multimers were stable to 60 degrees C, unlike the hyaluronate-proteoglycan complex.     

Thermal expansion of blood vessels in low cryogenic temperatures Part I: A new experimental device

As part of the ongoing effort to study the mechanical behavior of biological material during cryopreservation processes, the current study focuses on thermal expansion of blood vessels at low cryogenic temperatures. The current paper (Part I) describes a new experimental device for thermal expansion measurements of blood vessels in typical conditions of vitrification, which are associated with rapid cooling rates. For validation purposes, the thermal strain of frozen arteries in the absence of cryoprotectants was measured, and found to be about 10% larger than that of polycrystalline water; this observation agrees with literature data. The companion paper (Part II) reports on experimental results of cryoprotectants permeated with VS55, DP6, and 7.05 M DMSO at high cooling rates applicable to vitrification.     

Balint groups as 'shared care' in the area of mental health in primary medicine

This paper describes how Balint groups can be effective for primary care doctors and how leaders of these groups can act as role models in the interdisciplinary, experiential learning experience. The paper describes the way Balint activity helps the facilitation of a dialogue between mental health professionals and primary care physicians. While these groups have been found to improve the sensitivity of doctors in their interaction with patients, Balint groups, with the joint leadership of professionals from different disciplines, can be seen as an effective method to improve primary care and mental health cooperation. These issues are discussed and appropriate examples outlined offering an uncommon perspective on an interesting topic to promote an integrated, shared model of care.     

Occasional intraguild predation structuring small mammal assemblages: the marsupial Didelphis aurita in the Atlantic Forest of Brazil

The didelphid marsupial, Didelphis aurita, is suggested as an intraguild predator and as key‐species in small mammal assemblages of the Atlantic Forest of Brazil. The field experiments required to test this hypothesis are complex to implement, but the recent revival of regression methods offers a viable alternative. Here we use the dynamic and static regression methods to determine the importance of D. aurita as a competitor and intraguild predator. Capture–recapture data from two localities in the Rio de Janeiro State were used, Garrafão (municipality of Guapimirim), a coastal forest of the Serra do Mar, and Barra de Maricá, a costal sand dune vegetation. Population and microhabitat variables were monitored from April 1997 to April 2003 in Garrafão, and from January 1986 to July 1990 in Barra de Maricá. Microhabitat variables were related to Canopy, Plant, Litter and Rock covers, Obstruction from 0 to 1.5 m, and Number of logs. Exploitation competition was tested by the dynamic method, which models the effects of D. aurita on the per capita growth rate of a species. Interference by predation or competition was tested by the static method, where the abundance of D. aurita at trap stations was regressed against the abundance of other small mammals, after removal of any variation associated with microhabitat factors. Exploitation competition was not detected, but the interference of D. aurita was pervasive, affecting all small mammals studied in the two localities. The clear avoidance of D. aurita by all small mammals tested in two localities of different physiognomies indicates that it functions as an intraguild predator, even if actual predation by D. aurita is an occasional event.     

Effect of spontaneous twist on DNA minicircles

Monte Carlo simulations are used to study the effect of spontaneous (intrinsic) twist on the conformation of topologically equilibrated minicircles of dsDNA. The twist, writhe, and radius of gyration distributions and their moments are calculated for different spontaneous twist angles and DNA lengths. The average writhe and twist deviate in an oscillatory fashion (with the period of the double helix) from their spontaneous values, as one spans the range between two neighboring integer values of intrinsic twist. Such deviations vanish in the limit of long DNA plasmids.     

The genus Prevotella in cystic fibrosis airways

Airway disease resulting from chronic bacterial colonization and consequential inflammation is the leading cause of morbidity and mortality in patients with Cystic Fibrosis (CF). Although traditionally considered to be due to only a few pathogens, recent re-examination of CF airway microbiology has revealed that polymicrobial communities that include many obligate anaerobes colonize lower airways. The purpose of this study was to examine Prevotella species in CF airways by quantitative culture and phenotypic characterization. Expectorated sputum was transferred to an anaerobic environment immediately following collection and examined by quantitative microbiology using a variety of culture media. Isolates were identified as facultative or obligate anaerobes and the later group was identified by 16S rRNA sequencing. Prevotella spp. represented the majority of isolates. Twelve different species of Prevotella were recovered from 16 patients with three species representing 65% of isolates. Multiple Prevotella species were often isolated from the same sputum sample. These isolates were biochemically characterized using Rapid ID 32A kits (BioMérieux), and for their ability to produce autoinducer-2 and β-lactamases. Considerable phenotypic variability between isolates of the same species was observed. The quantity and composition of Prevotella species within a patients’ airway microbiome varied over time. Our results suggest that the diversity and dynamics of Prevotella in CF airways may contribute to airway disease.     

toxin-mediated insect resistance in plants

We are currently in an interesting phase of plant biotechnology releases, both for the scientists responsible for these innovations who are beginning to see their ideas realized, and for the biotechnology companies that are starting to see a return on their investment. One of the most notable examples, is the introduction of transgenic crops that are engineered to express a Bacillus thuringiensis toxin that confers resistance to insect predation. However, the picture is not altogether positive - there is concern that the introduction of this technology was premature or should not have happened at all, and that the valuable insecticidal properties of Bacillus thuringiensis will be lost.