Cavity Optomechanics with Anderson-Localized Optical Modes

Confining photons in cavities enhances the interaction between light and matter. In cavity optomechanics, this enables a wealth of phenomena ranging from optomechanically induced transparency to macroscopic objects cooled to their motional ground state. Previous work in cavity optomechanics employed devices where ubiquitous structural disorder played no role beyond perturbing resonance frequencies and quality factors. More generally, the interplay between disorder, which must be described by statistical physics, and optomechanical effects has thus far been unexplored. Here, we demonstrate how sidewall roughness in air-slot photonic-crystal waveguides can induce sufficiently strong backscattering of slot-guided light to create Anderson-localized modes with quality factors as high as half a million and mode volumes estimated to be below the diffraction limit. We observe how the interaction between these disorder-induced optical modes and in-plane mechanical modes of the slotted membrane is governed by a distribution of coupling rates, which can exceed g_{o}/2π∼200  kHz, leading to mechanical amplification up to self sustained oscillations via optomechanical backaction. Our Letter constitutes the first steps towards understanding optomechanics in the multiple-scattering regime and opens new perspectives for exploring complex systems with a multitude of mutually coupled degrees of freedom.

Engineering nanoscale hypersonic phonon transport

Controlling vibrations in solids is crucial to tailor their elastic properties and interaction with light. Thermal vibrations represent a source of noise and dephasing for many physical processes at the quantum level. One strategy to avoid these vibrations is to structure a solid such that it possesses a phononic stop band, that is, a frequency range over which there are no available elastic waves. Here we demonstrate the complete absence of thermal vibrations in a nanostructured silicon membrane at room temperature over a broad spectral window, with a 5.3-GHz-wide bandgap centred at 8.4 GHz. By constructing a line-defect waveguide, we directly measure gigahertz guided modes without any external excitation using Brillouin light scattering spectroscopy. Our experimental results show that the shamrock crystal geometry can be used as an efficient platform for phonon manipulation with possible applications in optomechanics and signal processing transduction.

Analysis of a dehiscence zone endo-polygalacturonase in oilseed rape (Brassica napus) and Arabidopsis thaliana: evidence for roles in cell separation in dehiscence and abscission zones, and in stylar tissues during pollen tube growth

The oilseed rape (Brassica napus) endo-polygalacturonase (endo-PG) RDPG1 is involved in middle lamella breakdown during silique opening. We investigated tissue-specific expression of RDPG1 in transgenic Arabidopsis thaliana. Cellular localization of endo-PG protein in Arabidopsis siliques was determined by immuno-electron microscopy. An Arabidopsis orthologue, ADPG1, was isolated and aligned with the sequence of RDPG1. The proximal 5' sequences as well as introns are largely conserved. Analysis of the histological GUS-staining pattern of two RDPG1 promoter-GUS (beta-glucuronidase) constructs in transgenic Arabidopsis revealed that the conserved proximal part of the 5'-flanking region directs expression in dehiscence zones of siliques and anthers, floral abscission zones and stylar tissues during pollen tube growth, branch points between stems and pedicel and expression associated with the apical meristem of seedlings, while the distal part of the RDPG1 5'-flanking region contains elements involved in vascular-associated expression in petals, cotyledons and roots. Subsequent RT-PCR analysis, on RNA from the corresponding rape tissues, confirms the staining pattern revealed in transgenic Arabidopsis, thereby justifying the use of Arabidopsis as a reliable model system for analysis of oilseed rape regulatory sequences.

A comparison of patient-controlled analgesia with lornoxicam versus morphine in patients undergoing lumbar disk surgery

The analgesic efficacy and tolerability of lornoxicam (Xefo; Nycomed Pharma A/S, Roskilde, Denmark), a new nonsteroidal antiinflammatory drug, was compared with that of morphine in a double-blind, randomized, parallel-group study of 96 patients with at least moderate pain after lumbar microsurgical discectomy. Both drugs were administered i.v. via a patient-controlled analgesia (PCA) for up to 24 h postoperatively. Efficacy was assessed by comparing mean hourly pain intensity differences, mean hourly pain relief, and total pain relief (TOTPAR) values derived from a 5-point verbal rating scores of pain intensity and pain relief at several time points over 24 h. Of 79 patients included in a per-protocol analysis, statistically significant equivalence of lornoxicam and morphine was shown by TOTPAR values of 31.6 and 28.9, respectively (P = 0.048). Trends toward slightly faster onset of analgesia with morphine and slightly greater PCA demands with lornoxicam were observed initially, which may partly have been due to a higher baseline pain intensity in the lornoxicam group. Lornoxicam caused fewer adverse events than morphine (21.7% vs 38.0% of patients, respectively), most of which were mild or moderate in severity. These results suggest that lornoxicam is an alternative to morphine when administered by PCA for the treatment of moderate to severe postoperative pain.

IMPLICATIONS

After surgery for lumbar disk disease, patients obtained statistically equivalent pain relief with lornoxicam and morphine when administered by patient-controlled analgesia. However, lornoxicam was associated with a lower incidence of adverse events. This study suggests that lornoxicam provides an alternative to morphine for the treatment of postoperative pain.

A surprising effect of extraction conditions on the mobility of some plant virus coat proteins in SDS-PAGE

The coat protein from purified particles of pea seedborne mosaic potyvirus (PSbMV) moves in SDS-PAGE with an apparent molecular weight (M(r)) of 36 kDa. However, extracts of PSbMV infected plants prepared with SDS or urea contain PSbMV immunoreactive proteins with apparent M(r) 39 kDa as well as 36 kDa. The low mobility form may be generated from the apparent M(r) 36 kDa form by incubating purified PSbMV particles with healthy plant sap in the presence of denaturing agents. A similar effect is observed with bean yellow mosaic potyvirus, but not with three viruses outside the potyvirus group. Experiments suggest that a soluble plant enzyme is responsible for the conversion, which apparently takes place only in vitro under denaturing conditions. This phenomenon may lead to erroneous conclusions about the M(r) of some viral coat proteins. However, the conversion can be prevented by heat treatment of the plant tissue prior to extraction.

Detection of a 45 kD protein derived from the N terminus of the pea seedborne mosaic potyvirus polyprotein in vivo and in vitro

A 45 kD protein (Pro1) derived from the N terminus of the pea seedborne mosaic potyvirus (PSbMV) polyprotein has been detected in extracts of infected pea plants and among in vitro translation products of PSbMV genomic RNA. The genomic region coding for the first 231 amino acids of the PSbMV polyprotein was cloned and expressed in Escherichia coli as a fusion protein with beta-galactosidase. A rabbit antiserum raised against the fusion protein recognized an approximately 45 kD protein in immunoblots of extracts of PSbMV-infected pea leaves that was not present in extracts of healthy leaves. The highest concentration of the 45 kD protein was found in extracts of young leaves, suggesting the protein may be rapidly degraded in vivo. After in vitro translation of PSbMV genomic RNA in a wheat germ extract, the antiserum immunoprecipitated a 45 kD polypeptide as well as some lower molecular weight translation products. On the other hand, an approximately 90 kD polypeptide was immunoprecipitated from in vitro translation products of genomic RNA in a rabbit reticulocyte lysate, corresponding to the combined molecular weights of Pro1 and the helper component predicted from genomic sequence data.

In vivo expression of the 29000 Mr protein from RNA-2 of pea early browning tobravirus

The purpose of this work has been to investigate in vivo transcription and translation products from an open reading frame (ORF) located downstream of the coat protein (CP) cistron on RNA-2 of pea early browning virus (PEBV). This work was initiated as a step towards elucidation of the significance of this putative gene. Sequence data on RNA-2 suggest that a 29,600 Mr (29.6K) protein is translated from the ORF in question. Hybridization with ORF-specific probes on Northern blots with RNA from infected plants showed that PEBV synthesizes a subgenomic RNA encoding CP (RNA-2a) with a size of 3000 nucleotides (nt) and that a putative subgenomic RNA (RNA-2b) encoding the 29.6K protein appears to have a size of 1600 nt. This is 300 nt less than the size predicted from the sequencing data. For antibody production, a cDNA fragment harbouring 85% of the 29.6K ORF was cloned into the pUEX3 expression vector. The resulting plasmid expresses the 29.6K protein as a fusion protein with beta-galactosidase and this protein was used for raising antiserum containing specific anti-29.6K protein antibodies. By using these antibodies on immunoblots it was demonstrated that the 29.6K protein is expressed in infected plants.

Expression of the CD15 differentiation antigen (3-fucosyl-N-acetyl-lactosamine, LeX) on putative neutrophil adhesion molecules CR3 and NCA-160

The expression of the carbohydrate antigen 3-fucosyl-N-acetyl-lactosamine (CD15, LeX) on human neutrophil glycoproteins has been studied by immunoprecipitation and immunoblotting by using monoclonal antibody MC2. The antigen is expressed on membrane glycoproteins of approximate molecular mass 165 and 105 kDa. These glycoproteins include the complement receptor and adhesion molecule, CR3, in which the beta-chain (CD18, 105 kDa) shows much greater expression than the alpha-chain (CD11b, 165 kDa). Most of the 165 kDa CD15 antigen is accounted for by expression on the carcinoembryonic antigen (CEA)-related molecule NCA160. Other members of this family, NCA95, NCA90 and NCA55, which are also found in neutrophils, do not express the CD15 antigen. There is a marked increase in the surface expression of CD15, CR3 and the antigen recognized by anti-CEA antibodies upon activation of neutrophils by the chemotactic peptide N-formylmethionyl-leucylphenylalanine.

Purification of plant viruses and virus coat proteins by high performance liquid chromatography

High performance liquid chromatography (HPLC) gel filtration has been successfully applied in the purification of elongated and isometric plant viruses. Two different approaches have been tested. In one approach, semi-purified virus particles were dissociated with lithium chloride and the released coat proteins purified by HPLC gel filtration. The purified coat protein was highly immunogenic and gave rise to very specific antisera reacting with intact virus particles as well as with SDS-denatured coat protein monomers. This method is generally applicable only for elongated viruses since many isometric viruses are not dissociated by the lithium chloride treatment. The second approach consisted in gel filtration of native, undissociated virus particles and could be used both with elongated and isometric viruses. Both methods were fast and simple to perform and removed all or most of the contaminating plant proteins as judged by sodium dodecylsulphate gel electrophoresis followed by silver staining or by immunoblotting with antiserum against healthy plant extracts. With both methods the recovery of virus coat protein was about 30% on average.

Characterization of human neutrophil glycoproteins expressing the CD15 differentiation antigen (3-fucosyl-N-acetyllactosamine)

The expression of the CD15 antigen, 3-fucosyl N-acetyllactosamine, on neutrophil glycoproteins has been studied by SDS gel electrophoresis and immunoblotting. The antigen is expressed on several glycoproteins, both intracellularly and on the cell surface. Each subcellular compartment appears to contain a specific antigen. A soluble, granule glycoprotein (Mr 80-90K) probably accounts for most of the intracellular staining detected immunohistochemically. Membrane glycoproteins of Mr, 85-90K and 25K are associated with granule membranes, the latter being an integral membrane protein. The CD15 antigen is expressed on several cell surface glycoproteins with Mr in the range of 165K and 105K. These antigens are also contained in an intracellular pool which is brought to the surface on activation of the cells with chemotactic peptides. The 165K and 105K antigens show identical electrophoretic mobility to two of the major glycoproteins detectable by PAS or protein staining of gels of detergent extracts of cell membranes. These glycoproteins include the complement receptor, CR3. The beta chain of CR3 (105K) and to a lesser extent the alpha chain (165K) express CD15; however, most of the CD15 antigen is associated with other glycoproteins of these molecular masses.

Characterization of the IgA receptor from human polymorphonuclear leucocytes

Human polymorphonuclear leucocytes (PMNs) will phagocytose yeasts opsonized with specific affinity-purified human serum IgA. PMNs also bind to Sepharose beads coated with IgA or IgG, but not to beads coated with bovine serum albumin (BSA) or horseradish peroxidase (HRP). Binding to IgA-Sepharose stimulates the cells to release lysozyme. Affinity chromatography of 125I-labelled PMN membrane proteins on IgA-Sepharose results in isolation of a polypeptide of apparent 60,000 MW. The protein, which is not bound to IgG-Sepharose under the same conditions, appears as a diffuse band on SDS-PAGE, suggesting it is heavily glycosylated.

A survey of IgA protease production among clinical isolates of Proteeae

A collection of 100 strains of Proteeae, in which all species within the tribe were represented, was examined for IgA protease production. The strains were isolated from various clinical specimens from sick and healthy persons in several countries. IgA protease-producing strains were not found amongst species of Providencia and Morganella but were common in Proteus spp. All the strains of P. mirabilis and P. penneri and many of the strains of P. vulgaris examined produced an EDTA-sensitive protease that cleaved the IgA heavy chain outside the hinge region. The proteus enzyme was different in this respect from the EDTA-sensitive, hinge-cutting proteases of other bacteria. The ability to produce IgA protease was unrelated to the O antigenicity, biotype or bacteriocin type of the strain. IgA protease production may be an important virulence mechanism for Proteus strains.

Proteus mirabilis strains of diverse type have IgA protease activity

A strain of Proteus mirabilis associated with chronic urinary tract infection was found to produce an EDTA-sensitive IgA protease that cleaved the IgA heavy chain into two fragments at sites different from those attacked by other microbial IgA1 proteases. Another 14 P. mirabilis strains of diverse type and from various clinical conditions also produced a similar IgA protease. This enzyme may be a virulence determinant of P. mirabilis.

N-CAM in cerebrospinal fluid: a marker of synaptic remodelling after acute phases of multiple sclerosis?

We made a longitudinal study of the cerebrospinal fluid (CSF) neural cell adhesion molecule (N-CAM) content of 20 multiple sclerosis (MS) patients in an acute phase, and 10 in a non-acute phase. Both groups were compared with a control group of 23 subjects without neurological diseases. All MS patients were subjected to two or three lumbar punctures for collection of CSF samples, once a week. N-CAM analysis was performed by an enzyme-linked immunosorbent assay (ELISA) method. Comparison of N-CAM concentrations of the first CSF samples from each MS group with the control group values showed statistically different (lower) levels in the non-acute phase MS patients. Furthermore, a statistically significant increase of CSF N-CAM emerged from a comparison of the values of the first, second, and third samples of the acute phase MS patients group. This increase paralleled the patients' clinical improvement.

Biosynthesis of the neural cell adhesion molecule: characterization of polypeptide C

The biosynthesis of the neural cell adhesion molecule (N-CAM) was studied in primary cultures of rat cerebral glial cells, cerebellar granule neurons, and skeletal muscle cells. The three cell types produced different N-CAM polypeptide patterns. Glial cells synthesized a 135,000 Mr polypeptide B and a 115,000 Mr polypeptide C, whereas neurons expressed a 200,000 Mr polypeptide A as well as polypeptide B. Skeletal muscle cells produced polypeptide B. The polypeptides synthesized by the three cell types were immunochemically identical. The membrane association of polypeptide C was investigated with methods that distinguish peripheral and integral membrane proteins. Polypeptide C was found to be a peripheral membrane protein, whereas polypeptides A and B were integral membrane proteins with cytoplasmic domains of approximately 50,000 and approximately 25,000 Mr, respectively. The affinity of the membrane binding of polypeptide C increased during postnatal development. The posttranslational modifications of polypeptide C were investigated in glial cell cultures, and it was found to be N-linked glycosylated and sulfated.

High cerebrospinal fluid concentration of glial fibrillary acidic protein (GFAP) in patients with normal pressure hydrocephalus

The concentration of glial fibrillary acidic protein (GFAP) in lumbar cerebrospinal fluid (CSF) was measured in 12 patients with normal pressure hydrocephalus (NPH) 11 patients with primary degenerative dementia (PDD), 8 patients with various other neurological diseases, and 18 patients without signs of organic nervous disease (controls). Mean CSF GFAP concentration was significantly higher in NPH patients: 96 +/- 23 ng/ml (SEM) when compared with PDD patients: 8.2 +/- 1.9 ng/ml (P less than 0.01), or with controls: 4.3 +/- 0.7 ng/ml (P less than 0.01). Only 2 NPH patients had a GFAP concentration within the range of the control group (2-14 ng GFAP/ml CSF). No significant differences were found between the PDD patients and the control group, or between the group of patients with other neurological diseases and the control group. In addition, a rostro-caudal gradient of GFAP in CSF could be demonstrated. In 6 NPH and 2 PDD patients both ventricular and lumbar CSF samples were investigated. In all cases the ventricular GFAP concentration was higher than the lumbar concentration. The difference was statistically significant (P less than 0.01). Our results suggest that determination of CSF GFAP concentration might be of diagnostic value in discrimination between NPH patients and patients with enlarged ventricles associated with degenerative brain disease.

Quantification of glial fibrillary acidic protein (GFAP) in human body fluids by means of ELISA employing a monoclonal antibody

Soluble glial fibrillary acidic protein (GFAP) was quantified in human cerebrospinal fluid (CSF) and amniotic fluid. A normal value in lumbar CSF of 4.3 +/- 0.7 ng GFAP/ml (mean +/- SEM) was obtained from 18 non-neurological patients. Increased GFAP concentrations in CSF were found in patients with intracranial tumours or with normal pressure hydrocephalus, while normal values were found in multiple sclerosis patients and in patients with degenerative dementia. In addition, a concentration gradient between ventricular and lumbar CSF was demonstrated, the GFAP content being significantly higher in ventricular than in lumbar samples. Amniotic fluids from normal pregnancies contained 13 +/- 5.5 ng GFAP/ml (N = 117). Increased GFAP concentrations were observed in amniotic fluid from some but not all pregnancies with fetal anencephaly or encephalocele, but not from pregnancies with fetal spina bifida or any of the other fetal malformations investigated. The quantification method was an enzyme-linked immunosorbent assay employing a monoclonal antibody specific for GFAP.

Enzyme-linked immunosorbent assay for the human glial fibrillary acidic protein using a mouse monoclonal antibody

Two enzyme-linked immunosorbent assays (ELISAs) have been developed for the quantification of soluble human glial fibrillary acidic protein (GFAP). The specificity of the assays for GFAP is ensured by the use of a monoclonal antibody directed against a GFAP-specific antigenic determinant. One ELISA is a four-layer system working in the concentration range 5-600 ng GFAP/ml. The other ELISA is a five-layer system and includes a biotin/avidin binding reaction. The latter assay has a working range of 0.5-60 ng GFAP/ml. The assays may be used for quantification of GFAP in CSFs, amniotic fluids, and extracts or homogenates of normal and pathological brain material. GFAP in serum could not be quantified because of unidentified interference. CSFs from 18 nonneurological subjects were found to contain 2-14 ng GFAP/ml (mean 4.1 ng/ml), whereas amniotic fluids from 50 normal pregnant women contained up to 24 ng GFAP/ml (mean 12.4 ng/ml). GFAP concentrations in CSFs from 32 multiple sclerosis patients were found not to be elevated compared to the control group.

Glial fibrillary acidic protein in amniotic fluids from pregnancies with fetal neural tube defects

The glial fibrillary acidic protein (GFAP) is the subunit protein of intermediate filaments in astrocytes and closely related cell types. By means of an enzyme immunoassay we have determined the concentration of GFAP in amniotic fluids from normal pregnancies and from pregnancies complicated by various fetal malformations. The group of 20 cases of fetal anencephaly had a significantly higher mean amniotic fluid GFAP concentration (115 micrograms/l +/- 133.6 (S.D.), range 6-378 micrograms/l) than the control group of 117 normal pregnancies (13 micrograms/l +/- 5.5 (S.D.), range 0-31 micrograms/l), (P less than 0.001). Two cases of fetal encephalocele likewise had very high amniotic fluid GFAP concentrations. None of the other cases of fetal malformations investigated, including 12 cases of spina bifida, had increased amniotic fluid GFAP concentrations. We conclude that determination of the amniotic fluid GFAP concentration may give additional information in the prenatal diagnosis of fetal nervous system malformations.

Mouse monoclonal antibodies reacting with human brain glial fibrillary acidic protein

Three different epitopes on the glial fibrillary acidic protein (GFAP) have been identified by means of three monoclonal antibodies. The antibodies were named anti-GFAP 1, anti-GFAP 2, and anti-GFAP 3. Antibody specificities were investigated by several techniques including indirect immunoprecipitation, immunoblotting, and immunohistochemistry. The anti-GFAP 1 antibodies recognized an epitope found on GFAP from all three species tested: human, rat, and ox, but in addition a reaction was observed with cells not containing GFAP. The epitope recognized by anti-GFAP 2 was present on GFAP from human and ox, but apparently not on rat GFAP; the anti-GFAP 2 antibodies also reacted with antigen(s) other than GFAP. In contrast, the epitope defined by anti-GFAP 3 has proved absolutely specific for GFAP in human, rat, and ox.