Determinants of liposome partitioning in aqueous two-phase systems: Evaluation by means of a factorial design

This article evaluates the influence of five parameters on liposome partitioning in aqueous two-phase systems (ATPSs), composed of poly(ethyleneglycol) (PEG)/dextran (Dx), using the factorial experimental design together with a multiple regression. Mathematical models to quantify the influence of these parameters, individually and/or jointly, on liposome partitioning in ATPS were developed. The models were statistically tested and verified by experimentation. This approach was then used to define the conditions for the preferential accumulation of liposomes in the top PEG-rich phase. The models predicted a significant effect of liposome surface charge, PEG molecular weight, phase-forming polymer concentration, and phosphate ion concentration on the partition behavior of liposomes. For negatively charged liposomes, it was found that the smaller the molecular weight of PEG and polymer concentration and the larger the phosphate ion concentration, the greater the partition coefficient of the liposomes. No significant effect of pH, at the range of 6-8, on liposome partitioning was noted. This approach has led to the development of an optimal two-phase system where 90% of negatively charged liposomes accumulated in the PEG phase. In addition to the general scientific value of this research, it has a technological importance as ATPSs may be useful for removing the unentrapped drug from liposomes during their preparation for pharmaceutical applications. (c) 1996 John Wiley & Sons, Inc.     

CHARACTERIZATION OF TWO CHLORELLA VULGARIS (CHLOROPHYCEAE) STRAINS ISOLATED FROM WASTEWATER OXIDATION PONDS1

We report here on the characterization and isolation of two ecotypes of Chlorella vulgaris Beyerinck that coexist in wastewater reservoirs. One ecotype (C1) contains high amounts of chlorophyll b, is capable of autotrophic growth, and can utilize only a few organic solutes for growth. The second ecotype (C2) contains low amounts of chlorophyll b, requires vitamin B₁₂, and can support its growth with a broad range of organic compounds. Of the two ecotypes, the latter showed slower growth rates when light was the sole source of energy. Cells of C2-type Chlorella attained higher photosynthetic activities than C1-type cells at saturating irradiances. However, their low chlorophyll b content and lower light utilization efficiency suggest that C2-type Chlorella contains relatively low amounts of light-harvesting antennae, a disadvantage in severely light-limited ecosystems like wastewater reservoirs. We hypothesize that the two Chlorella types coexist by adopting different lifestyles: C1-type cells rely largely on their photosynthetic potential for energy conservation and growth, whereas C2-type cells may exploit their heterotrophic properties for this purpose.     

GPCRDB information system for G protein-coupled receptors

The GPCRDB is a molecular class-specific information system that collects, combines, validates and disseminates heterogeneous data on G protein-coupled receptors (GPCRs). The database stores data on sequences, ligand binding constants and mutations. The system also provides computationally derived data such as sequence alignments, homology models, and a series of query and visualization tools. The GPCRDB is updated automatically once every 4-5 months and is freely accessible at http://www.gpcr.org/7tm/.     

Saccharomyces cerevisiae protein phosphatase 2A performs an essential cellular function and is encoded by two genes.

Two genes (PPH21 and PPH22) encoding the yeast homologues of protein serine-threonine phosphatase 2A have been cloned from a Saccharomyces cerevisiae genomic library using a rabbit protein phosphatase 2A cDNA as a hybridization probe. The PPH genes are genetically linked on chromosome IV and are predicted to encode polypeptides each with 74% amino acid sequence identity to rabbit type 2A protein phosphatase, indicating once again the extraordinarily high degree of sequence conservation shown by protein-phosphatases from different species. The two PPH genes show less than 10% amino acid sequence divergence from each other and while disruption of either PPH gene alone is without any major effect, the double disruption is lethal. This indicates that protein phosphatase 2A activity is an essential cellular function in yeast. Measurement of type 2A protein phosphatase activity in yeast strains lacking one or other of the genes indicates that they account for most, if not all, protein phosphatase 2A activity in the cell.     

The activation of the atypical PKC zeta in light‐induced retinal degeneration and its involvement in L‐DNase II control

Light‐induced retinal degeneration is characterized by photoreceptor cell death. Many studies showed that photoreceptor demise is caspase‐independent. In our laboratory we showed that leucocyte elastase inhibitor/LEI‐derived DNase II (LEI/L‐DNase II), a caspase‐independent apoptotic pathway, is responsible for photoreceptor death. In this work, we investigated the activation of a pro‐survival kinase, the protein kinase C (PKC) zeta. We show that light exposure induced PKC zeta activation. PKC zeta interacts with LEI/L‐DNase II and controls its DNase activity by impairing its nuclear translocation. These results highlight the role of PKC zeta in retinal physiology and show that this kinase can control caspase‐independent pathways.     

An interaction between climate change and infectious disease drove widespread amphibian declines

Climate change might drive species declines by altering species interactions, such as host–parasite interactions. However, few studies have combined experiments, field data, and historical climate records to provide evidence that an interaction between climate change and disease caused any host declines. A recently proposed hypothesis, the thermal mismatch hypothesis, could identify host species that are vulnerable to disease under climate change because it predicts that cool‐ and warm‐adapted hosts should be vulnerable to disease at unusually warm and cool temperatures, respectively. Here, we conduct experiments on Atelopus zeteki, a critically endangered, captively bred frog that prefers relatively cool temperatures, and show that frogs have high pathogen loads and high mortality rates only when exposed to a combination of the pathogenic chytrid fungus (Batrachochytrium dendrobatidis) and high temperatures, as predicted by the thermal mismatch hypothesis. Further, we tested various hypotheses to explain recent declines experienced by species in the amphibian genus Atelopus that are thought to be associated with B. dendrobatidis and reveal that these declines are best explained by the thermal mismatch hypothesis. As in our experiments, only the combination of rapid increases in temperature and infectious disease could account for the patterns of declines, especially in species adapted to relatively cool environments. After combining experiments on declining hosts with spatiotemporal patterns in the field, our findings are consistent with the hypothesis that widespread species declines, including possible extinctions, have been driven by an interaction between increasing temperatures and infectious disease. Moreover, our findings suggest that hosts adapted to relatively cool conditions will be most vulnerable to the combination of increases in mean temperature and emerging infectious diseases.     

Diagnoses and factors associated with medical evacuation and return to duty among nonmilitary personnel participating in military operations in Iraq and Afghanistan

Background

Nonmilitary personnel play an increasingly critical role in modern wars. Stark differences exist between the demographic characteristics, training and missions of military and nonmilitary members. We examined the differences in types of injury and rates of returning to duty among nonmilitary and military personnel participating in military operations in Iraq and Afghanistan.

Methods

We collected data for nonmilitary personnel medically evacuated from military operations in Iraq and Afghanistan between 2004 and 2007. We compared injury categories and return-to-duty rates in this group with previously published data for military personnel and identified factors associated with return to duty.

Results

Of the 2155 medically evacuated nonmilitary personnel, 74.7% did not return to duty. War-related injuries in this group accounted for 25.6% of the evacuations, the most common causes being combat-related injuries (55.4%) and musculoskeletal/spinal injuries (22.9%). Among individuals with non–war-related injuries, musculoskeletal injuries accounted for 17.8% of evacuations. Diagnoses associated with the highest return-to-duty rates in the group of nonmilitary personnel were psychiatric diagnoses (15.6%) among those with war-related injuries and noncardiac chest or abdominal pain (44.0%) among those with non–war-related injuries. Compared with military personnel, nonmilitary personnel with war-related injuries were less likely to return to duty (4.4% v. 5.9%, p = 0.001) but more likely to return to duty after non–war-related injuries (32.5% v. 30.7%, p = 0.001).

Interpretation

Compared with military personnel, nonmilitary personnel were more likely to be evacuated with non–war-related injuries but more likely to return to duty after such injuries. For evacuations because of war-related injuries, this trend was reversed.In modern warfare, injuries sustained in combat have never been the leading source of attrition among soldiers. In World War I, World War II and the Korean War, respiratory and infectious diseases were the top reasons for hospital admissions among service members. By the Vietnam Conflict, non-battle injuries had supplanted respiratory illness as the leading cause of hospital admissions and have remained the leading cause ever since.^1,2The principal causes for medical evacuation of military personnel from US operations in Iraq and Afghanistan were recently described in a large four-year epidemiologic study.³ In descending order, the leading reasons were musculoskeletal conditions, combat-related injuries, neurologic symptoms and psychiatric disorders; the last category surpassed combat-related injuries as the number two reason in the latter half of both engagements. However, nonmilitary personnel were not included in that study. Over the past three years, nonmilitary members, including US Department of Defense civilians, private contractors and diplomats, have comprised about 50% of personnel serving in Iraq and about two-thirds of those serving in Afghanistan.^4,5Several reasons may explain why the types of injury and the return-to-duty rates differ between military and nonmilitary personnel. First, the motivations for overseas deployment might differ between the groups. Whereas some civilian personnel (e.g., diplomats) may be assigned to positions in Iraq and Afghanistan, virtually all private contractors volunteer for their jobs. In contrast, most military members have little choice in their deployment. Second, military and nonmilitary members assigned to war zones have different occupational specialties, living conditions and regulations to which they must adhere. Especially for junior military personnel, jobs tend to be more dangerous, living environments more austere and regulations more stringent. Finally, unlike military personnel, who are paid regardless of deployment status, most contractors’ pay is contingent upon continued employment in theatres of operation. In addition, nonmilitary personnel are generally compensated with higher salaries than service members in comparable occupational specialties.In civilian cohorts, many of these factors have been shown to influence return-to-work rates in a variety of contexts. Studies of the effect of financial compensation on work status after injury have generally shown a direct correlation between return-to-work rates and higher income levels.^6,7 Similar associations have also been found between return-to-work rates and job satisfaction and coping mechanisms, factors that may be influenced by work conditions and perceived control over one’s environment.^8–10The objectives of our study were threefold: to ascertain whether the reasons for medical evacuation from military operations differed between military and nonmilitary personnel; to determine whether return-to-duty rates differed between the two groups; and to identify factors that influence return-to-duty rates among nonmilitary members.     

l-Arginine and l-Canavanine Metabolism in Jack Bean, Canavalia ensiformis (L.) DC. and Soybean, Glycine max (L.) Merr

Studies have been conducted with the arginase (l-arginine amidinohydrolase, EC 3.5.3.1) of two legumes: jack bean, Canavalia ensiformis (L.) DC., a l-canavanine-containing plant and soybean, Glycine max, a canavanine-free species. Analyses of the arginase obtained from gradient-purified mitochondria of these legumes revealed that the arginine-dependent (ADA) and canavanine-dependent activities (CDA) were localized within this organelle.     

ALFY-Controlled DVL3 Autophagy Regulates Wnt Signaling,Determining Human Brain Size

Primary microcephaly is a congenital neurodevelopmental disorder of reduced head circumference and brain volume, with fewer neurons in the cortex of the developing brain due to premature transition between symmetrical and asymmetrical cellular division of the neuronal stem cell layer during neurogenesis. We now show through linkage analysis and whole exome sequencing, that a dominant mutation in ALFY, encoding an autophagy scaffold protein, causes human primary microcephaly. We demonstrate the dominant effect of the mutation in drosophila: transgenic flies harboring the human mutant allele display small brain volume, recapitulating the disease phenotype. Moreover, eye-specific expression of human mutant ALFY causes rough eye phenotype. In molecular terms, we demonstrate that normally ALFY attenuates the canonical Wnt signaling pathway via autophagy-dependent removal specifically of aggregates of DVL3 and not of Dvl1 or Dvl2. Thus, autophagic attenuation of Wnt signaling through removal of Dvl3 aggregates by ALFY acts in determining human brain size.     

Floral evolution in Lithospermum (Boraginaceae): independent origins of similar flower types

In Lithospermum (Boraginaceae), floral diversity is quite large, with variation in individual quantitative and qualitative traits as well as suites of floral characteristics. The present study utilizes phylogenetic, morphometric and developmental methodologies to investigate patterns of floral evolution, of individual and suites of traits, in the genus and among related genera. The evolutionary patterns of eight quantitative and five qualitative traits were reconstructed, and morphometrics and the evolution of floral morphospace were examined in the genus. Floral developmental patterns were established with light and scanning electron microscopy. Phylogenetic analyses provided evidence that derived flower types have each evolved multiple times, with differences in the manner in which these flower types arose. Floral morphospace has increased throughout the evolution of Lithospermum. Floral developmental patterns and cell lengths of floral organs at anthesis provided evidence that, in Lithospermum, an increase in the length of the sexual organs of flowers involves both longer cells and a greater number of mitotic divisions, but an increase in the length of the corolla is primarily a result of a larger number of cell divisions. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2016, 180 , 213–228.