Optical trapping force reduction and manipulation of nanoporous beads.

We studied the interaction of infrared optical traps with controlled-pore glass (CPG) beads in aqueous medium. The lateral optical trapping force and stiffness were experimentally found considerably smaller than those of their solid counterparts. The simulation using an average refractive index revealed significant losses of effective trapping efficiency, which quantitatively agreed well with experimentally fitted curves.

Translation and manipulation of silicon nanomembranes using holographic optical tweezers.

We demonstrate the use of holographic optical tweezers for trapping and manipulating silicon nanomembranes. These macroscopic free-standing sheets of single-crystalline silicon are attractive for use in next-generation flexible electronics. We achieve three-dimensional control by attaching a functionalized silica bead to the silicon surface, enabling non-contact trapping and manipulation of planar structures with high aspect ratios (high lateral size to thickness).

Optical tweezers directed one-bead one-sequence synthesis of oligonucleotides.

An optical tweezers directed parallel DNA oligonucleotide synthesis methodology is described in which controlled pore glass (CPG) beads act as solid substrates in a two-stream microfluidic reactor. The reactor contains two parallel sets of physical confinement features that retain beads in the reagent stream for synthetic reaction but allow the beads to be optically trapped and transferred between the reagent and the inert streams for sequence programming. As a demonstration, we synthesized oligonucleotides of target sequence 25-nt, one deletion and one substitution using dimethoxytrityl (DMT) nucleoside phosphoramidite chemistry.

Production of ceramides causes apoptosis during early neural differentiation in vitro.

To investigate signal transduction pathways leading to apoptosis during the early phase of neurogenesis, we employed PCC7-Mz1 cells, which cease to proliferate and begin to differentiate into a stable pattern of neurons, astroglial cells, and fibroblasts upon incubation with retinoic acid (RA). As part of lineage determination, a sizable fraction of RA-treated cultures die by apoptosis. Applying natural long-chain C(16)-ceramides as well as membrane-permeable C(2)/C(6)-ceramide analogs caused apoptosis, whereas the biologically nonactive C(2)-dihydroceramide did not.

The protein kinase C (PKC) substrate GAP-43 is already expressed in neural precursor cells, colocalizes with PKCeta and binds calmodulin.

Expression of the growth-associated protein of 43-kDa (GAP-43), which is described as a postmitotic, neuron-specific major protein kinase C (PKC) substrate, was investigated in the murine embryonic carcinoma cell line PCC7-Mz1 which develops into a brain-tissue-like pattern of neuronal, fibroblast-like and astroglial cells upon stimulation with all-trans retinoic acid (RA). GAP-43 expression was very low in stem cells, but increased on mRNA and protein level within the 12 h after differentiation was initiated. While the P1 promoter of the GAP-43 gene gave rise to a 1.

Expression of protein kinase C gene family members is temporally and spatially regulated during neural development in vitro.

We used primary cultures of rat hippocampal neurons and PCC7-Mz1 cells to correlate the expression of the protein kinase C (PKC) gene family with specific events during neural differentiation. Multipotent PCC7-Mz1 embryonic carcinoma stem cells develop into a tissue-like pattern of neuronal, fibroblast-like and astroglial cells by all-trans retinoic acid (RA) treatment. Western blot analyses demonstrate that PKCalpha, betaI, gamma, theta, mu, lambda, and zeta were constitutively expressed but the expression of PKCbetaII, delta, epsilon, and eta was up-regulated three days after addition of RA when cells mature morphologically.

Activation of protein kinase C alpha and/or epsilon enhances transcription of the human endothelial nitric oxide synthase gene.

In primary human umbilical vein endothelial cells (HUVECs), incubation with phorbol-12-myristate-13-acetate (PMA) enhanced basal and bradykinin-stimulated nitric oxide production. In the HUVEC-derived cell line EA.hy 926, PMA and phorbol-12,13-dibutyrate stimulated endothelial nitric oxide synthase (NOS III) mRNA expression in a concentration- and time-dependent manner.

Retinoic acid induces apoptosis-associated neural differentiation of a murine teratocarcinoma cell line.

Incubation with all-trans retinoic acid (RA) induces PCC7-Mz1 embryonic carcinoma cells to cease proliferation and to develop into a tissue-like pattern of neuronal, astroglial, and fibroblast-like derivatives over a period of several days. Concomitant with the induction of differentiation by RA, a sizable fraction of the Mz1 stem cells detaches and dies, with the maximal level of cell death achieved after 10 h of RA treatment. This RA-induced cell death fulfills all criteria of apoptosis, including nuclear condensation, intranucleosomal DNA degradation, expression of cysteine aspases (caspases), and the formation of apoptotic bodies.

Phosphorylation of GAP-43 (growth-associated protein of 43 kDa) by conventional, novel and atypical isotypes of the protein kinase C gene family: differences between oligopeptide and polypeptide phosphorylation.

GAP-43 (growth-associated protein of 43 kDa; also known as neuromodulin, P-57, B-50 and F-1) is a neuronal calmodulin binding protein and a major protein kinase C (PKC) substrate in mammalian brain. Here we describe the phosphorylation by and the site specificity of different PKC isotypes. The conventional PKC beta 1 and the novel PKCs delta and epsilon effectively phosphorylated recombinant GAP-43 in vitro; atypical PKC zeta did not.

The myristoylated alanine-rich C-kinase substrate (MARCKS) is sequentially phosphorylated by conventional, novel and atypical isotypes of protein kinase C.

The myristoylated alanine-rich C-kinase substrate (MARCKS) is the major protein kinase C (PKC) substrate in many cell types including fibroblasts and brain cells. Here we describe the phosphorylation of MARCKS and the site specificity for different PKC isotypes. Conventional (c)PKC beta 1, novel (n)PKC delta and nPKC epsilon efficiently phosphorylated the MARCKS protein in vitro.

Captopril in congestive heart failure.

Vasodilator therapy is used widely for the treatment of congestive heart failure irrespective of its origin. The acute and long-term effects of captopril were studied in 50 patients with congestive heart failure due to valvular incompetence, hypertension, cardiomyopathy, and ischaemic heart disease. Haemodynamic studies were performed in all patients.