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S Holler

Publications and source records attributed to S Holler.

9 recordsLinked to original sources
PubMed2003

Shift of whispering-gallery modes in microspheres by protein adsorption.

Biosensors based on the shift of whispering-gallery modes in microspheres accompanying protein adsorption are described by use of a perturbation theory. For random spatial adsorption, theory predicts that the shift should be inversely proportional to microsphere radius R and proportional to protein surface density and excess polarizability. Measurements are found to be consistent with the theory, and the correspondence enables the average surface area occupied by a single protein to be estimated. These results are consistent with crystallographic data for bovine serum albumin. The theoretical shift for adsorption of a single protein is found to be extremely sensitive to the target region, with adsorption in the most sensitive region varying as 1/R(5/2). Specific parameters for single protein or virus particle detection are predicted.

Adsorption↗
PubMed2002

Patterns of canal and otolith afferent input convergence in frog second-order vestibular neurons.

Second-order vestibular neurons (2 degrees VN) were identified in the isolated frog brain by the presence of monosynaptic excitatory postsynaptic potentials (EPSPs) after separate electrical stimulation of individual vestibular nerve branches. Combinations of one macular and the three semicircular canal nerve branches or combinations of two macular nerve branches were stimulated separately in different sets of experiments. Monosynaptic EPSPs evoked from the utricle or from the lagena converged with monosynaptic EPSPs from one of the three semicircular canal organs in ~30% of 2 degrees VN. Utricular afferent signals converged predominantly with horizontal canal afferent signals (74%), and lagenar afferent signals converged with anterior vertical (63%) or posterior vertical (37%) but not with horizontal canal afferent signals. This convergence pattern correlates with the coactivation of particular combinations of canal and otolith organs during natural head movements. A convergence of afferent saccular and canal signals was restricted to very few 2 degrees VN (3%). In contrast to the considerable number of 2 degrees VN that received an afferent input from the utricle or the lagena as well as from one of the three canal nerves (~30%), smaller numbers of 2 degrees VN (14% of each type of 2 degrees otolith or 2 degrees canal neuron) received an afferent input from only one particular otolith organ or from only one particular semicircular canal organ. Even fewer 2 degrees VN received an afferent input from more than one semicircular canal or from more than one otolith nerve (~7% each). Among 2 degrees VN with afferent inputs from more than one otolith nerve, an afferent saccular nerve input was particularly rare (4-5%). The restricted convergence of afferent saccular inputs with other afferent otolith or canal inputs as well as the termination pattern of saccular afferent fibers are compatible with a substrate vibration sensitivity of this otolith organ in frog. The ascending and/or descending projections of identified 2 degrees VN were determined by the presence of antidromic spikes. 2 degrees VN mediating afferent utricular and/or semicircular canal nerve signals had ascending and/or descending axons. 2 degrees VN mediating afferent lagenar or saccular nerve signals had descending but no ascending axons. The latter result is consistent with the absence of short-latency macular signals on extraocular motoneurons during vertical linear acceleration. Comparison of data from frog and cat demonstrated the presence of a similar organization pattern of maculo- and canal-ocular reflexes in both species.

Animals↗
PubMed2001

Treatment of urban wastewater in a membrane bioreactor at high organic loading rates.

Membrane bioreactors can replace the activated sludge process and the final clarification step in municipal wastewater treatment. The combination of bioreactor and crossflow microfiltration allows for a high chemical oxygen demand (COD) reduction of synthetic wastewater. From biomass, grown at high production rates in the aerobic bioreactor, energy rich biogas can be obtained in a subsequent anaerobic bioreactor. In this paper, experimental data from a laboratory scale membrane bioreactor are presented. The degradation of synthetic wastewater at short hydraulic retention times down to 1.5 h has been studied. The organic loading rate (OLR) has been varied in the range of 6-13 kg m(-3) per day. At steady state a high quality filtrate could be obtained at different operating conditions. At biomass concentrations of 10-22 g l(-1), COD reduction was above 95%.

Aerobiosis↗
PubMed2001

Plane-specific brainstem commissural inhibition in frog second-order semicircular canal neurons.

Commissural inputs of identified second-order semicircular canal neurons were studied by separate stimulation of each of the three canal nerves on either side in the vitro frog brains. The spatial pattern of these inputs was further investigated in those second-order canal neurons that received a monosynaptic input from only one ipsilateral canal nerve (91%). Since similar results were obtained in the presence as in the absence of the cerebellum, commissural inputs must have been relayed via fibers crossing in the brainstem. Following stimulation of individual semicircular canal nerves, commissural inputs were either inhibitory or excitatory. A commissural inhibition was evoked in the majority of the recorded neurons (79%) by stimulation of the coplanar semicircular canal nerve on the contralateral side. In the remaining neurons, a commissural excitatory input was evoked. A commissural excitation, originating from the two noncoplanar semicircular canals, predominated in most (68%) of the recorded neurons and was independent of the type of second-order canal neuron. The onset latency of the canal plane-specific commissural inhibitory potentials was di- or trisynaptic. Stimulation of the contralateral VIIIth nerve evoked excitatory commissural responses. The canal plane-specific commissural inhibition therefore might have been masked by commissural excitatory responses as in earlier studies. The similar organization of the canal plane-specific commissural inhibition in frog and cat corroborates the notion of a phylogenetically conservative, basic vestibular organization. The presence of a canal plane-unspecific commissural excitation, however, appears to be a feature that is specific to frogs. The functional implications of these similarities and differences are discussed.

Animals↗
PubMed2000

Enhanced backward-directed multiphoton-excited fluorescence from dielectric microcavities

We demonstrate theoretically and experimentally that one-, two-, and three-photon excited fluorescence from dye molecules in spherical microcavities has an asymmetrical angular distribution and is enhanced in the backward direction. The enhancement ratios (of intensities at 180 degrees and 90 degrees ) are 9, 5, and 1.8 for three-, two-, and one-photon excitation, respectively. Even larger ratios are expected for microspheres with an index of refraction larger than that used in the experiments. Because of the reciprocity principle and concentration of the incident wave inside particles, the backward enhancement is expected to occur even with nonspherical particles.

Journal Article↗
PubMed2000

Expression of decorin, biglycan, and collagen type I in human renal fibrosing disease.

BACKGROUND: The extracellular matrix proteoglycans decorin and biglycan may have a pathogenic role in renal fibrosing disease via regulation of the activity of growth factors, such as transforming growth factor-beta, and effects on collagen type I fibrillogenesis. The expression of decorin and biglycan in human glomerular diseases characterized by mesangial sclerosis is unknown. METHODS: Decorin, biglycan, and collagen type I were localized immunohistochemically in human renal biopsy cases of amyloidosis (N = 18), diabetic nephropathy (N = 11), fibrillary glomerulonephritis (N = 5), immunotactoid glomerulopathy (N = 5), light-chain deposition disease (N = 4), idiopathic mesangial sclerosis (N = 4), and nephrosclerosis (N = 6), and in morphologically normal tissues obtained from tumor nephrectomies (N = 8). Decorin and biglycan mRNA synthesis was evaluated by in situ hybridization. RESULTS: Decorin and biglycan protein were not identified in normal glomeruli. Decorin accumulated in amyloid deposits, but not in deposits of fibrillary glomerulonephritis or immunotactoid glomerulopathy. Biglycan weakly accumulated in amyloid deposits, and both decorin and biglycan weakly stained mesangial nodules in cases of morphologically advanced light-chain deposition disease and diabetic nephropathy. In all analyzed cases, irrespective of the underlying disease, decorin and biglycan accumulated in glomeruli in areas of fibrous organization of the urinary space and in areas of tubulointerstitial fibrosis. Biglycan, but not decorin, accumulated in the neointima of arteriosclerotic blood vessels. Decorin and biglycan mRNA synthesis was detected at sites of proteoglycan accumulation in glomeruli, interstitium, and neointima. Collagen type I colocalized with decorin and biglycan deposits. CONCLUSIONS: Differences in extracellular matrix proteoglycan composition may be diagnostically useful in distinguishing morphologically similar diseases. Distinct patterns of proteoglycan expression may be related to modulation of specific growth factor activity in different glomerular diseases.

Amyloidosis↗