A concept for miniaturized 3-D cell culture using an extracellular matrix gel

This paper presents a novel method to embed, anchor, and cultivate cells in a controlled 3-D flow-through microenvironment. This is realized using an etched silicon pillar flow chamber filled with extracellular matrix (ECM) gel mixed with cells. At 4 degrees C, while in liquid form, ECM gel is mixed with cells and injected into the chamber. Raising the temperature to 37 degrees C results in a gel, with cells embedded. The silicon pillars both stabilize and increase the surface to volume ratio of the gel. During polymerization the gel shrinks, thus creating channels, which enables perfusion through the chip. The pillars increase the mechanical stability of the gel permitting high surface flow rates without surface modifications. Within the structure cells were still viable and proliferating after 6 days of cultivation. Our method thus makes it possible to perform medium- to long-term cultivation of cells in a controlled 3-D environment. This concept opens possibilities to perform studies of cells in a more physiological environment compared to traditional 2-D cultures on flat substrates.     

Atom‐Efficient Synthesis of Alkynylfluoroborates Using BF3‐Based Frustrated Lewis Pairs

A sterically demanding amine, 1,2,2,6,6‐pentamethylpiperidine (PMP), forms a highly reactive Lewis acid–base pair with boron trifluoride. This pair reacts with terminal acetylenes to give the products of C(sp)?H borylation, previously unknown tri‐ and tetraalkynylboron compounds. Trialkynylfluoroborates can serve as surrogates of alkynyltrifluoroborates for C?C coupling reactions. Using aqueous NaOH, PMP can be recovered from its tetrafluoroborate salt, which is formed as a C?H borylation byproduct. Combining the discovered borylation reactivity with the PMP recovery provides a straightforward and atom‐efficient approach to synthetically useful alkynylfluoroborates.     

Ultrafast Multidimensional Laplace NMR Using a Single‐Sided Magnet

Laplace NMR (LNMR) consists of relaxation and diffusion measurements providing detailed information about molecular motion and interaction. Here we demonstrate that ultrafast single‐ and multidimensional LNMR experiments, based on spatial encoding, are viable with low‐field, single‐sided magnets with an inhomogeneous magnetic field. This approach shortens the experiment time by one to two orders of magnitude relative to traditional experiments, and increases the sensitivity per unit time by a factor of three. The reduction of time required to collect multidimensional data opens significant prospects for mobile chemical analysis using NMR. Particularly tantalizing is future use of hyperpolarization to increase sensitivity by orders of magnitude, allowed by single‐scan approach.     

Duplexiphane: a polyaromatic receptor containing two adjoined Delta-shaped cavities for an efficient hopping of a single silver cation

A simple synthesis of a polyaromatic receptor (i.e., duplexiphane) containing two adjoined Delta-shaped cavities is accomplished via an intramolecular (double) McMurry coupling, and its structure is established by X-ray crystallography. The binding of silver cation to duplexiphane showed that it binds only a single silver cation with significantly higher efficiency (>100 times) than a model compound containing only one pi-prismand-like cavity, and the single silver cation hops intramolecularly between the two adjoined cavities in duplexiphane.     

Study of the interaction of GFG tripeptide with cesium perfluorooctanoate micelles by means of NMR spectroscopy and MD simulations

The interaction of glycyl-phenylalanyl-glycine (GFG) with bilayers formed by cesium perfluorooctanoate (CsPFO) in water was investigated in the isotropic phase by means of 1H NMR and molecular dynamics (MD) simulations. Details on the preferential location of the different residues of GFG were obtained from selective variations of chemical shift with peptide concentration and of line width in the presence of the paramagnetic ion Mn2+. The analysis of 1H NMR spectra recorded at different concentrations and temperatures allowed the association constant and the enthalpy change upon binding to be evaluated. MD simulations highlighted the hydrogen bonds formed between the different GFG functional groups and the micelle. Both NMR and MD gave indications of high affinity of GFG with the micelle, with the N-terminal residue anchoring on the surface via hydrogen bonds with the micelle COO(-) groups.     

Topical application of temoporfin-loaded invasomes for photodynamic therapy of subcutaneously implanted tumours in mice: a pilot study

Temoporfin (mTHPC) represents a very potent second-generation synthetic photosensitizer. It has shown to be effective in the photodynamic therapy of early or recurrent oral carcinomas, in the palliative treatment of refractory oral carcinomas and in the treatment of primary non-melanomatous tumours of the skin of the head and neck. Until now for all positive findings an intravenous application of the photosensitizer was mandatory. In the case of cutaneous malignant or non-malignant diseases a topical application of the drug onto the site of the disease followed by illumination, would be advantageous. Unfortunately, mTHPC is a highly hydrophobic drug with a low percutaneous absorption. The purpose of this experiment was to investigate the photodynamic efficacy of novel mTHPC-loaded invasomes after their topical application onto the skin of mice bearing the subcutaneously implanted human colorectal tumour HT29 followed by photoirradiation. Invasomes are vesicles containing in addition to phospholipids a mixture of terpenes (cineole, citral and d-limonene) or only one terpene (citral) and ethanol, as penetration enhancers. This was a pilot study since until now no data are available about the efficacy of mTHPC in the photodynamic therapy of HT29 tumours after its topical application. The aim of this experiment was to investigate whether a mTHPC-loaded invasome formulation can reduce tumour size by photodynamic therapy or at least to find a formulation slowing down tumour growth compared to the control group (mice without any treatment). The groups of mice treated with mTHPC–invasomes containing 1% of the terpene mixture prior to photoirradiation showed a significantly smaller (p < 0.05) tumour increase compared to control groups (mice without any treatment and mice only photoirradiated).     

On a class of optimal partition problems related to the Fučík spectrum and to the monotonicity formulae

In this paper we give an unified approach to some questions arising in different fields of nonlinear analysis, namely: (a) the study of the structure of the Fuík spectrum and (b) possible variants and extensions of the monotonicity formula by Alt-Caffarelli-Friedman [1]. In the first part of the paper we present a class of optimal partition problems involving the first eigenvalue of the Laplace operator. Beside establishing the existence of the optimal partition, we develop a theory for the extremality conditions and the regularity of minimizers. As a first application of this approach, we give a new variational characterization of the first curve of the Fuík spectrum for the Laplacian, promptly adapted to more general operators. In the second part we prove a monotonicity formula in the case of many subharmonic components and we give an extension to solutions of a class of reaction-diffusion equation, providing some Liouville-type theorems.Received: 27 December 2003, Accepted: 29 January 2004, Published online: 2 April 2004Mathematics Subject Classification (2000): 35J65 (58E05)Work partially supported by MIUR project Metodi Variazionali ed Equazioni Differenziali Non Lineari     

A refined algorithm to simulate latex colloid agglomeration at high ionic strength

This study is focussed on the simulation of particle agglomeration at relatively high ionic strength using a refined stochastic algorithm developed in the context of parcel-tracking approaches. For that purpose, experimental data of both diffusion-limited and reaction-limited aggregation of latex particles were obtained using dynamic light scattering techniques for different initial particle sizes (diameters ranging from 24 to 495 nm) and at various chemical conditions (ionic strength between 0.5 and 2 M with NaCl or CaCl\(_2\) solutions). The experimental data collected have been compared to numerical results obtained with the refined parcel-tracking algorithm for particle agglomeration which has been developed. Results show that the evolution of the aggregate diameters over time can be properly captured by the present model with the value of the aggregate fractal dimension that is extracted from experimental data.     

Erratum to: Inter-laboratory exercise with an aim to compare methods for 90Sr and 239,240Pu determination in environmental soil samples

Journal of Radioanalytical and Nuclear Chemistry - In the original article, the LOD assigned to method Sr-B in Table&nbsp;1 was published incorrectly as 24&nbsp;Bq/kg, the correct LOD for...     

Effects of flavonoid derivatives on human microvascular endothelial cells

Some natural compounds, including flavonoids, are active in vasculature re-growth during hair follicle disruption, but their effects have not been yet evaluated directly on microvascular endothelial cells. Skin vascularisation regulates the physiological blood supply required for hair growth and its dysregulation is the basis of several human diseases. Follicle-derived vascular endothelial growth factor (VEGF) release from follicular keratinocytes promotes perifollicular vascularisation and increases follicle and hair size, while blockade of VEGF-mediated angiogenesis leads to impaired hair growth. Here, we tested three flavonoids, namely visnadin (VSD), hesperidin (HSP) and baicalin (BC), on cultured human microvascular endothelial cells (HMEC), comparing their effects with minoxidil (MXD), a synthetic drug broadly used in the treatment of androgenetic alopecia. The response to these compounds was assayed in terms of endothelial survival, proliferation, tubulogenesis and proangiogenic signalling. We show that BC promotes HMEC proliferation, while both VSD and MXD enhance tubulogenesis. Interestingly, only HSP increases VEGFR-2 phosphorylation.