On stiffness of scaffolds for bone tissue engineering—a numerical study

Tissue scaffolds are typically designed and fabricated to match native bone properties. However, it is unclear if this would lead to the best tissue ingrowth outcome within the scaffold as neo-tissue keeps changing the stiffness of entire construct. This paper presents a numerical method to address this issue for design optimization and assessment of tissue scaffolds. The elasticity tensors of two different types of bones are weighted by different multipliers before being used as the targets in scaffold design. A cost function regarding the difference between the effective elasticity tensor, calculated by the homogenization technique, and the target tensor, is minimized by using topology optimization procedure. It is found that different stiffnesses can lead to different remodeling results. The comparison confirms that bone remodeling is at its best when the scaffold elastic tensor matches or is slightly higher than the elastic properties of the host bone.     

In vitro and in vivo antimuscarinic effects of (-)cis 2,3-dihydro-3-(4-methylpiperazinylmethyl)-2-phenyl-1,5 benzothiazepin-4-(5H)one HCl (BTM-1086) in guinea pig peripheral tissues

The potency and selectivity of (-)cis-2,3-dihydro-3-(4-methylpiperazinylmethyl)-2-phenyl-1,5 benzothiazepin-4-(5H)one HCl (BTM-1086) for muscarinic receptor subtypes was compared in functional assay systems, in guinea pig peripheral tissues, to known reference drugs: atropine (nonselective), pirenzepine (M1), AF-DX 116 (M2) and HHSiD (M3). Like atropine, BTM-1086 was a potent, nonselective, competitive muscarinic antagonist with no detectable antispasmodic activity in urinary bladder or ileal muscle. In vivo, in the guinea pig cystometrogram, BTM-1086 depressed intravesical bladder pressure (PvesP) with the same efficacy and potency as oxybutynin, a drug used clinically for the treatment of urinary incontinence. The pharmacological profile of BTM-1086, however, suggests that it may not be suitable for development for bladder dysfunction disorders.     

Isolation of proteins assembled in lipid body membranes during fat mobilization in cucumber cotyledons

Lipid bodies from fat-mobilizing cotyledons of cucumber and other Cucurbitaceae were investigated. Proteins and glycoproteins were analyzed by electrophoresis and then used to characterize the lipid body membrane at different stages of cell development. Contaminations by other membranes or organelles were ruled out by comparing the main constituents from the endoplasmic reticulum, cytosol, glyoxysomes and protein bodies with the pattern of the lipid body membrane, considering both the prevalent peptides and the dominating glycoproteins. Among the proteins of lipid body membranes in ripening and germinating cotyledons, a 90-kDa peptide was found as unique marker of lipid bodies at the stage of fat mobilization. The 90-kDa protein was purified, and antibodies against it were raised in rabbits. By means of immunoprecipitation and electrophoretic analysis it was demonstrated that the synthesis of the 90-kDa form located in lipid bodies shows a transient increase and subsequent decline, with maximal values being observed at day 3 of germination. At this stage, the rate of de novo synthesis was compared considering lipid body proteins and other organellar proteins. The 90-kDa protein appeared as the lipid body constituent that is synthesized and assembled in the organelle by far at the highest rates.     

Oxiranylphenyl esters from Pimpinella diversifolia

The major components of the essential oil from roots of Pimpinella diversifolia, gathered in the Kumaun Region of India, have been identified as the (+)-Z-2-methyl-2-butenoate (angelate) and (+)-isobutyrate esters of 4-methoxy-2-(E-3-methyloxiranyl)phenol. Aromatic ¹³C NMR resonances of these compounds and their synthetic acetate analog, as well as those of 2-methoxy-4-(E-3-methyloxiranyl)phenyl acetate prepared from isoeugenol, were found to be in excellent agreement with calculated values. Comparison of the EIMS of the natural and synthetic products with those reported for compounds previously identified as 2-methoxy-4-(E-3-methyloxiranyl)phenyl esters indicates that they also have the 4-methoxy-2-(E-3-methyloxiranyl)phenyl structure.     

Corrosive extracellular polysaccharides of the rock-inhabiting model fungus Knufia petricola

Extremophiles - Melanised cell walls and extracellular polymeric matrices protect rock-inhabiting microcolonial fungi from hostile environmental conditions. How extracellular polymeric substances...     

Nitrogen cycling and storage in <Emphasis Type="Italic">Gagea spathacea</Emphasis> (Liliaceae): ecological insights for protecting a rare woodland species

Strategies to globally protect biological diversity are often hampered by an insufficient ecological knowledge about target species. This also applies to Gagea spathacea (Liliaceae), a ‘vulnerable’ woodland spring geophyte with a distribution largely restricted to the lowlands of Central Europe. We studied whether the species’ linkage to highly fertile forest soils is related to its high nitrogen (N) demands during its short developmental cycle. We hypothesized that the species exhibits a highly efficient N (re)cycling strategy, characterized by efficient resorption of N from the leaves and reallocation to bulbs at the end of the growing season. To test this assumption, we conducted a ¹⁵N tracer experiment and quantified ¹⁵N flows between soil, leaves, bulbs, and roots. Our findings support our hypothesis that G. spathacea is exceptionally efficient in recycling N, shown by the resorption of 68% of leaf N and its reallocation to bulbs at the end of the growing season. After 6 weeks of growth the plant showed a distinct shift in its N metabolism: The C:N ratio of leaves strongly increased and those of bulbs decreased, leaf ¹⁵N enrichment and recovery started to decrease, while total plant ¹⁵N recovery remained constant, indicating no further N uptake from the soil. Leaf N reallocation to bulbs was accompanied by a twofold increase of the bulbs’ biomass. Because of the stenoecious behaviour of G. spathacea, a careful protection and sustainable management of G. spathacea forest habitats is necessary, particularly in its Central European core area.     

The Plasmodium translocon of exported proteins component EXP2 is critical for establishing a patent malaria infection in mice

Export of most malaria proteins into the erythrocyte cytosol requires the Plasmodium translocon of exported proteins (PTEX) and a cleavable Plasmodium export element (PEXEL). In contrast, the contribution of PTEX in the liver stages and export of liver stage proteins is unknown. Here, using the FLP/FRT conditional mutatagenesis system, we generate transgenic Plasmodium berghei parasites deficient in EXP2, the putative pore‐forming component of PTEX. Our data reveal that EXP2 is important for parasite growth in the liver and critical for parasite transition to the blood, with parasites impaired in their ability to generate a patent blood‐stage infection. Surprisingly, whilst parasites expressing a functional PTEX machinery can efficiently export a PEXEL‐bearing GFP reporter into the erythrocyte cytosol during a blood stage infection, this same reporter aggregates in large accumulations within the confines of the parasitophorous vacuole membrane during hepatocyte growth. Notably HSP101, the putative molecular motor of PTEX, could not be detected during the early liver stages of infection, which may explain why direct protein translocation of this soluble PEXEL‐bearing reporter or indeed native PEXEL proteins into the hepatocyte cytosol has not been observed. This suggests that PTEX function may not be conserved between the blood and liver stages of malaria infection.