Excitation of surface plasmon polaritons by diffraction-free and vector beams.

Surface plasmon polaritons (SPPs) are traditionally excited by plane waves within the Rayleigh range of a focused transverse-magnetic (TM) Gaussian beam. Here we investigate and confirm the coupling between SPPs and two-dimensional Gaussian and Bessel-Gauss wave packets, as well as one-dimensional light sheets and space-time wave packets. We encode the incoming wavefronts with spatially varying states of polarization; then we couple the respective TM components of radial and azimuthal vector beam profiles to confirm polarization-correlation and spatial-mode selectivity.

Plasmonic Interferometers as TREM2 Sensors for Alzheimer's Disease.

We report an effective surface immobilization protocol for capture of Triggering Receptor Expressed on Myeloid Cells 2 (TREM2), a receptor whose elevated concentration in cerebrospinal fluid has recently been associated with Alzheimer's disease (AD). We employ the proposed surface functionalization scheme to design, fabricate, and assess a biochemical sensing platform based on plasmonic interferometry that is able to detect physiological concentrations of TREM2 in solution. These findings open up opportunities for label-free biosensing of TREM2 in its soluble form in various bodily fluids as an early indicator of the onset of clinical dementia in AD.

Inhibitors of the proteasome reduce the accelerated proteolysis in atrophying rat skeletal muscles.

Several observations have suggested that the enhanced proteolysis and atrophy of skeletal muscle in various pathological states is due primarily to activation of the ubiquitin-proteasome pathway. To test this idea, we investigated whether peptide aldehyde inhibitors of the proteasome, N-acetyl-leucyl-leucyl-norleucinal (LLN), or the more potent CBZ-leucyl-leucyl-leucinal (MG132) suppressed proteolysis in incubated rat skeletal muscles. These agents (e.

Addendum: multicenter experience with cultured epidermal autograft for treatment of burns.

Since 1989 BioSurface Technology, Inc. (Cambridge, Mass.) has provided over 37,000 cultured epidermal autografts (CEAs) for more than 240 patients in 79 different burn centers in the United States and Europe.

Kinetic characterization of branched chain ketoacid dehydrogenase.

Initial velocity and product inhibition experiments were performed to characterize the kinetic mechanism of branched chain ketoacid dehydrogenase (the branched chain complex) activity. The results were directly compared to predicted patterns for a three-site ping-pong mechanism. Product inhibition experiments confirmed that NADH is competitive versus NAD+ and isovaleryl CoA is competitive versus CoA.

Quantitative control analysis of branched-chain 2-oxo acid dehydrogenase complex activity by feedback inhibition.

The potential for branched-chain 2-oxo acid dehydrogenase complex (BCOADC) activity to be controlled by feedback inhibition was investigated by calculating the Elasticity Coefficients for several feedback inhibitors. We suggest that feedback inhibition is a quantitatively important regulatory mechanism by which branched-chain 2-oxo acid dehydrogenase activity is regulated. The potential for control of enzyme activity is greater for NADH than for the acyl-CoA products, and suggests that factors that alter the redox potential may physiologically regulate BCOADC activity through a feedback inhibitory mechanism in vivo.

Burn-induced stimulation of lysosomal enzyme activity in skeletal muscle.

A localized burn injury to a rat hindlimb was used to investigate the proteolytic enzymes responsible for the burn-induced increase in muscle protein breakdown. In 10,000 x g pellets of muscle homogenates, burn stimulated (50% to 100%) protease activities with pH optima of 3, 5.5, and 7.

Effect of inhibitors of proteolysis and arachidonic acid metabolism on burn-induced protein breakdown.

A rat model has been developed to study the local effects of burn injury on the underlying muscle tissue. Protein turnover was measured in soleus muscle incubated in vitro in which both tyrosine release and protein synthesis was measured. A scald injury (3 seconds) to a small area of one hindlimb produces an increase in muscle proteolysis and is without effect on the soleus muscle of the contralateral leg.

A model to study local effects of thermal trauma on muscle metabolism.

To study local effects of burn on muscle in the absence of direct tissue damage, a rat's foot was insulated and one hindlimb was scalded by immersion in 85 degrees C water for 3 sec. Upon recovery, rats exhibited normal locomotion with both hindlimbs in spite of a full-thickness burn from ankle to knee. Thus the effects of the burn were not complicated by disuse atrophy.

Utilization of endogenous lipid, glycogen, and protein by rabbit aorta.

The utilization of endogenous stores by rabbit aorta in vitro was measured. In substrate-free medium glycogen disappearance may account for less than 20% of the tissue O2 consumption during incubations of less than 2-3 h. At longer times (or in the presence of glucose) glycogen catabolism is negligible.

Purification of rat kidney branched-chain oxo acid dehydrogenase complex with endogenous kinase activity.

A method was devised to purify branched-chain oxo acid dehydrogenase (BCOAD) from rat kidney which retains endogenous kinase activity. Incorporation of 32P into purified enzyme parallels the time course of enzyme inhibition by ATP. Phosphorylation occurs on a serine residue(s) of the 46000-mol.

Effect of insulin and leucine on protein turnover in rat soleus muscle after burn injury.

To investigate the effects of thermal injury on muscle protein turnover, net protein breakdown and incorporation of leucine into protein was measured in vitro in rat soleus at 3 days following a 3 sec burn to one hindlimb. The weight gain and food consumption of the burn injured animals was similar to that unburned animals. However, the burn caused an 11% decrease in soleus muscle weight and protein content.

The utilization by rabbit aorta of carbohydrates, fatty acids, ketone bodies, and amino acids as substrates for energy production.

The ability of rabbit aorta to oxidize various substrates was studied to determine which of these compounds may be energy substrates for vascular smooth muscle (VSM). Glucose, ketone bodies, medium-chain length fatty acids, branched-chain amino acids, and glutamine all are oxidized at comparable rates on a molar basis. Some other amino acids, long chain fatty acids, pyruvate and glycerol also are oxidized, but at lower rates.

Reversible ATP-induced inactivation of branched-chain 2-oxo acid dehydrogenase.

The branched chain 2-oxo acid dehydrogenase from rat skeletal muscle, heart, kidney and liver mitochondria can undergo a reversible activation-inactivation cycle in vitro. Similar results were obtained with the enzyme from kidney mitochondria of pig and cow. The dehydrogenase is markedly inhibited by ATP and the inhibition is not reversed by removing the nucleotide.

Leucine degradation in cell-free extracts of skeletal muscle.

Since skeletal muscle is the major site in the body for oxidation of leucine, isoleucine and valine, the pathway and control of leucine oxidation were investigated in cell-free preparations of rat muscle. Leucine was found to be transaminated to 4-methyl-2-oxopentanoate, which was then oxidatively decarboxylated. On differential centrifugation 70--80% of the transaminase activity was recovered in the soluble fraction of the cell, and the remaining amount in the mitochondrial fraction.