Echinocyte shapes: bending, stretching, and shear determine spicule shape and spacing

We study the shapes of human red blood cells using continuum mechanics. In particular, we model the crenated, echinocytic shapes and show how they may arise from a competition between the bending energy of the plasma membrane and the stretching/shear elastic energies of the membrane skeleton. In contrast to earlier work, we calculate spicule shapes exactly by solving the equations of continuum mechanics subject to appropriate boundary conditions. A simple scaling analysis of this competition reveals an elastic length Lambda(el), which sets the length scale for the spicules and is, thus, related to the number of spicules experimentally observed on the fully developed echinocyte.     

Changes in gene expression in Arabidopsis shoots during phosphate starvation and the potential for developing smart plants

Our aim was to generate and prove the concept of "smart" plants to monitor plant phosphorus (P) status in Arabidopsis. Smart plants can be genetically engineered by transformation with a construct containing the promoter of a gene up-regulated specifically by P starvation in an accessible tissue upstream of a marker gene such as beta-glucuronidase (GUS). First, using microarrays, we identified genes whose expression changed more than 2.5-fold in shoots of plants growing hydroponically when P, but not N or K, was withheld from the nutrient solution. The transient changes in gene expression occurring immediately (4 h) after P withdrawal were highly variable, and many nonspecific, shock-induced genes were up-regulated during this period. However, two common putative cis-regulatory elements (a PHO-like element and a TATA box-like element) were present significantly more often in the promoters of genes whose expression increased 4 h after the withdrawal of P compared with their general occurrence in the promoters of all genes represented on the microarray. Surprisingly, the expression of only four genes differed between shoots of P-starved and -replete plants 28 h after P was withdrawn. This lull in differential gene expression preceded the differential expression of a new group of 61 genes 100 h after withdrawing P. A literature survey indicated that the expression of many of these "late" genes responded specifically to P starvation. Shoots had reduced P after 100 h, but growth was unaffected. The expression of SQD1, a gene involved in the synthesis of sulfolipids, responded specifically to P starvation and was increased 100 h after withdrawing P. Leaves of Arabidopsis bearing a SQD1::GUS construct showed increased GUS activity after P withdrawal, which was detectable before P starvation limited growth. Hence, smart plants can monitor plant P status. Transferring this technology to crops would allow precision management of P fertilization, thereby maintaining yields while reducing costs, conserving natural resources, and preventing pollution.     

Design and implementation of a domain specific language for phylogenetic inference

Domain experts think and reason at a high level of abstraction when they solve problems in their domain of expertise. We present the design and motivation behind a domain specific language, called phi LOG, to enable biologists to program solutions to phylogenetic inference problems at a very high level of abstraction. The implementation infrastructure (interpreter, compiler, debugger) for the DSL is automatically obtained through a software engineering framework based on Denotational Semantics and Logic Programming.     

Targeting Brucella melitensis with polymeric nanoparticles containing streptomycin and doxycycline

Treatment and eradication of intracellular pathogens such as Brucella is difficult because infections are localized within phagocytic cells and most antibiotics, although highly active in vitro , do not actively pass through cellular membranes. Thus, an optimum strategy to treat these infections should address targeting of active drugs to the intracellular compartment where the bacteria replicate, and should prolong the release of the antibiotics so that the number of doses and associated toxicity can be reduced. We incorporated streptomycin and doxycycline into macromolecular nanoplexes with anionic homo- and block copolymers via cooperative electrostatic interactions among the cationic drugs and anionic polymers. The approach enabled simultaneous binding of both antibiotics into the nanoplexes, and their use resulted in an improvement in performance as compared with the free drugs. Administration of two doses of the nanoplexes significantly reduced the Brucella melitensis load in the spleens and livers of infected BALB/c mice. The nanoplexes were more effective than free drugs in the spleens (0.72-log and 0.51-log reductions, respectively) and in the livers (0.79-log and 0.42-log reductions, respectively) of the infected mice. Further research regarding the design of optimum nanoplex structures will be directed towards alterations in both the core and the shell properties to investigate the effects of the rates and pathways of entry into immune cells where the brucellae replicate.     

Characterization of IgM of Indian major carps and their cross-reactivity with anti-fish IgM antibodies

Indian major carps (IMC), rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala) were immunized with bovine serum albumin and the serum immunoglobulin M (IgM) was purified by affinity chromatography. The heavy and light chain of IgM of all the three species of IMC were about 88 and 26 kDa, respectively. Anti-fish IgM antibody against all the three species were raised in mice and the reaction of anti-fish IgM antibodies with IgM of all the three species of IMC were studied by Western blot. The anti-fish IgM antibodies reacted strongly with the heavy chain of the same species against which it was raised while the reactions with the heavy chain of other species were milder indicating some degree of epitope sharing among the heavy chains of IgM of IMCs. However, there was no cross-reaction with the light chain of any of the IgM.     

Safety of Intracoronary Infusion of 20 Million C-Kit Positive Human Cardiac Stem Cells in Pigs

Background

There is mounting interest in using c-kit positive human cardiac stem cells (c-kit^pos hCSCs) to repair infarcted myocardium in patients with ischemic cardiomyopathy. A recent phase I clinical trial (SCIPIO) has shown that intracoronary infusion of 1 million hCSCs is safe. Higher doses of CSCs may provide superior reparative ability; however, it is unknown if doses >1 million cells are safe. To address this issue, we examined the effects of 20 million hCSCs in pigs.

Methods

Right atrial appendage samples were obtained from patients undergoing cardiac surgery. The tissue was processed by an established protocol with eventual immunomagnetic sorting to obtain in vitro expanded hCSCs. A cumulative dose of 20 million cells was given intracoronarily to pigs without stop flow. Safety was assessed by measurement of serial biomarkers (cardiac: troponin I and CK-MB, renal: creatinine and BUN, and hepatic: AST, ALT, and alkaline phosphatase) and echocardiography pre- and post-infusion. hCSC retention 30 days after infusion was quantified by PCR for human genomic DNA. All personnel were blinded as to group assignment.

Results

Compared with vehicle-treated controls (n=5), pigs that received 20 million hCSCs (n=9) showed no significant change in cardiac function or end organ damage (assessed by organ specific biomarkers) that could be attributed to hCSCs (P>0.05 in all cases). No hCSCs could be detected in left ventricular samples 30 days after infusion.

Conclusions

Intracoronary infusion of 20 million c-kit positive hCSCs in pigs (equivalent to ~40 million hCSCs in humans) does not cause acute cardiac injury, impairment of cardiac function, or liver and renal injury. These results have immediate translational value and lay the groundwork for using doses of CSCs >1 million in future clinical trials. Further studies are needed to ascertain whether administration of >1 million hCSCs is associated with greater efficacy in patients with ischemic cardiomyopathy.     

Laribacter hongkongensis: an emerging pathogen of infectious diarrhea

Laribacter hongkongensis is relatively a new name in the list of bacterial pathogens for gastroenteritis and travelers’ diarrhea. Addition of another name increases burden on the enteric infections as a whole. L. hongkongensis belongs to Neisseriaceae family of β subclass Proteobacteria. L. hongkongensis was initially isolated in Hong Kong from blood and empyema of an alcoholic cirrhotic patient in 2001, followed by reports from Korea and China, representing a total of 38 articles in PubMed until April 2013. As of now, there is no report from Indian subcontinent where infectious diarrhea is very much prevalent and a major burden. This review provides information about the microbiological characteristics, consideration of an emerging pathogen, relative pathogenicity, genome and proteome content, resistance toward multiple antibiotics, adaptability to different stress, and other features since its time of discovery. Investigation for this bacterium may avoid misidentification as other microbial flora. Further studies like the geographical distribution, type of infection, disease burden, pathogenicity, or genomic exploration of this bacterium will be useful in characterizing them properly. This bacterium may possibly be the emerging threat to public health.     

Guanidine hydrochloride and urea-induced unfolding of Brugia malayi hexokinase

Guanidine hydrochloride and urea-induced unfolding of B. malayi hexokinase (BmHk), a tetrameric protein, was examined in detail by using various optical spectroscopic techniques, enzymatic activity measurements, and size-exclusion chromatography. The equilibrium unfolding of BmHk by guanidine hydrochloride (GdmCl) and urea proceeded through stabilization of several unique oligomeric intermediates. In the presence of low concentrations of GdmCl, stabilization of an enzymatically active folded dimer of BmHk was observed. However an enzymatically inactive dimer of BmHk was observed for urea-treated BmHk. This is the first report of an enzymatically active dimer of hexokinase from any human filarial parasite. Furthermore, although complete recovery of the native enzyme was observed on refolding of BmHk samples denatured by use of low concentrations of GdmCl or urea, no recovery of the native enzyme was observed for BmHk samples denatured by use of high concentrations of GdmCl or urea.