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PubMedDate not supplied

Microfluidics device for single cell gene expression analysis in Saccharomyces cerevisiae.

We have measured single-cell gene expression over time using a microfluidics-based flow cell which physically traps individual yeast using microm-sized structures (yeast jails). Our goal was to determine variability of gene expression within a cell over time, as well as variability between individual cells. In our flow cell system, yeast jails are fabricated out of PDMS and gene expression is visualized using fluorescently-tagged proteins of interest. Previously, single-cell yeast work has been done using micromanipulation on agar, or FACS. In the present device agar is eliminated, resulting in a superior optical system. The flow of media through the flow cell washes daughter cells away, eliminating the need for micromanipulation. Unlike FACS, the described device can track individual yeast over a time course of many hours. The flow cells are compatible with the needs of quantitative fluorescence microscopy, and allow simultaneous measurements to be done on a large number of individual yeast. We used these flow cells to determine the expression of HSP104-GFPand RAS2-YFP, genes known to affect yeast life span. The results demonstrate inter-cell variation in expression of both genes that could not have been detected without this single-cell analysis.

Bacterial Proteins↗
PubMed2006

Physiological monitoring and control in hemodialysis: state of the art and outlook.

Medical devices for monitoring and feedback control of physiological parameters of the dialysis patient were introduced in the early 1990s. They have a wide range of applications, aiming at increasing the safety and ensuring the efficiency of the treatment, and at an improved restoration of physiological conditions, leading to an overall reduction in morbidity and mortality. Such devices include sensors for the measurement of temperature, optical parameters and sound speed in blood, and electrical characteristics of the human body, and other parameters. Essential for the development of these devices is a detailed understanding of the pathophysiological background of a therapeutical problem. There is still a large potential to introduce new devices for further therapy improvement and automation. Also, the size of the hemodialysis market appears attractive; however, a new product has to meet several specific requirements in order to also become commercially successful. This review describes the therapeutic and technical principles of several available devices, reports on concepts for possible future devices, and presents a short overview on the market environment.

Blood Pressure↗
PubMed2004

[Neuromyelitis optica (Devic's disease): a severe variant of multiple sclerosis].

In three women aged 20, 34 and 21, with a combination of optic neuritis and transverse myelitis, the diagnosis of neuromyelitis optica (Devic's disease) was made. All three were treated with methylprednisolone. The first patient died from respiratory failure associated with tetraparesis, over two years after experiencing initial symptoms. The other two women recovered to varying extents. By employing a combination of clinical investigations and MRI supplemented by laboratory investigations, it is possible to differentiate neuromyelitis optica from multiple sclerosis. Neuromyelitis optica is treated by a stronger form of immunosuppression. Despite recorded differences it remains possible that these conditions form part of the same spectrum in which the genetic background is important. In neuromyelitis optica the underlying condition seems to be in the field of the human immune response.

Adult↗
PubMed1997

[Value of various intra- and extraoral therapeutic procedures for treatment of obstructive sleep apnea and snoring].

BACKGROUND: Recently intra- and extraoral devices are increasingly used in order to treat obstructive sleep apnea (OSA) and snoring. We examined the value of some devices according to the literature and our own results. PATIENTS AND METHODS: The mandibular advancing devices aim at increasing upper airway diameter. The active part of the tongue extending device (SnorEx) is a stamp connected to a piston which exerts pressure at the base of the tongue causing its forward displacement; we studied 23 patients. The principle of an optically stimulating system ("eye-cover", Snore-Stop) consists of a microphone and light diods which are integrated in the eye-cover. After detecting acoustic signals (for example snoring) optical stimuli are generated in front of the eyes, which are thought to induce arousals causing a change of body position and the reduction of the snoring and apneas; we measured 24 patients. The principle of the tongue-retainer (Snore-Master) is the fixation of the tongue in a ventral position, which is thought to enlarge the mesopharyngeal area; we studied 14 patients. The nose plaster (Breathe-Right) contains an elastic spine that pulls the alae nasi cranial. This manipulation is thought to increase the diameter of the nostril and reduce the airway resistance. We measured 30 patients with obstructive sleep apnea and 20 snoring subjects without obstructive sleep apnea. RESULTS: Regarding the mandibular advancing due to different appliance designs and study protocols variable success rates have been documented. In patients with mild to moderate obstructive sleep apnea a reduction of the sleep related breathing disorder could be shown. Non compliance (NC) to the tongue extending device was 75% (17/23). Non-compliance-patients were characterized by unacceptable local-side-effects of the prosthesis, lacking improvement of symptoms and of the respiratory disturbance index. Both tongue-retainer and -extensor are characterized by a high incidence of local side effects. Neither the eye-cover nor the nose plaster could improve the severity of obstructive sleep apnoe or snoring. In contrast to another study we could not show a significant effect of the tongue-retainer. CONCLUSIONS: Neither the nose plaster nor the optical stimulating device influenced the degree of obstructive sleep apnea and snoring. There are conflicting data regarding the tongue retainer. The high rate of non-compliant subjects and the low efficacy of the tongue extending prosthesis precludes large-scale use of this treatment modality in patients with obstructive sleep apnoe and snoring. In selected individuals suffering from a mild to moderate degree of obstructive sleep apnea with CPAP-inefficiency and -incompliance the mandibular advancing principle may be an therapeutic alternative to CPAP.

Equipment Design↗
PubMed2000

Gamma knife radiosurgery as a primary treatment for prolactinomas.

OBJECT: The purpose of this study was to estimate the efficacy of gamma knife radiosurgery (GKS) in controlling tumor growth and endocrinopathy associated with prolactinomas. METHODS: Between 1993 and 1997, 164 of 469 patients with pituitary adenomas treated by GKS harbored prolactinomas. The dose to the tumor margin ranged from 9 to 35 Gy (mean 31.2 Gy), and the visual pathways were exposed to a dose of less than 10 Gy. The mean tumor diameter was 13.4 mm. The mean follow-up time for 128 cases was 33.2 months (range 6-72 months). Tumor control was observed in all but two patients who underwent surgery 18 and 36 months, respectively, after GKS. Clinical cure was achieved in 67 cases. Clinical improvement was noted with a decrease in the hyperprolactinemia after GKS. Nonetheless, in 31 (29%) of 108 patients who were followed for more than 2 years no improvement in serum prolactin levels was demonstrated, although this could be normalized by bromocriptine administration after treatment. Nine infertile women became pregnant 2 to 13 months after GKS and all gave birth to normal children. There was no visual deterioration related to GKS. Five women experienced premature menopause. In these patients there was subtotal disappearance of the tumor and an empty sella developed. CONCLUSIONS: Gamma knife radiosurgery as a primary treatment for prolactinomas can be safe and effective both for controlling tumor growth and for normalization of prolactin hypersecretion. A higher margin dose (> or = 30 Gy) seemed to be associated with a better clinical outcome. Gamma knife radiosurgery may make prolactinomas more sensitive to the bromocriptine.

Humans↗
PubMed2005

Trimming of microring resonators by photooxidation of a plasma-polymerized organosilane cladding material.

As the complexity of microphotonic devices grows, the ability to precisely trim microring resonators becomes increasingly important. Photo-oxidation trimming uses UV irradiation to oxidize a cladding layer composed of polymerized hexamethyldisilane (6M2S) deposited with plasma-enhanced chemical vapor deposition (PECVD). PECVD 6M2S has optical properties that are compatible with microring devices, and its high cross linking renders it insoluble. Photo-oxidation decreases the refractive index of PECVD 6M2S by nearly 4%, permitting large resonance shifts that are not feasible with thermal trimming techniques. Resonance shifts from single-mode, 100 microm diameter Si3N4 (n =2.2) rings were as large as 12.8 nm for the TE mode and 23.5 nm for the TM mode.

Journal Article↗
PubMed2001

High-spin iron(II) as a semitransparent partner for tuning europium(III) luminescence in heterodimetallic d-f complexes.

The segmental ligand 2-[6-(N,N-diethylcarbamoyl)pyridin-2-yl]-1,1'-dimethyl-5,5'-methylene-2'-(6-methylpyridine-2-yl)bis[1H-benzimidazole] (L3) reacts with a stoichiometric mixture of LnIII (Ln = La, Eu, Gd) and M(II) (M = Zn, Fe) in acetonitrile to produce selectively the heterodimetallic triple-stranded helicates (HHH)-[LnM(L3)3]5+. In these complexes, M(II) is pseudooctahedrally coordinated by the three wrapped bidentate binding units, thus forming a noncovalent tripod which organizes the three unsymmetrical tridentate segments to give ninefold coordination to LnIII. The introduction of a methyl group at the 6 position of the terminal pyridine in L3 sterically reduces the complexing ability of the bidentate segment for M(II). Spectroscopic (ESI-MS, UV/Vis/NIR, NMR), magnetic and electrochemical measurements show that 1) the head-to-head-to-head triple helical complexes (HHH)-[LnM(L3)3]5+ are quantitatively formed in solution only for ligand concentrations larger than 0.01 M, 2) FeII adopts a pure high-spin electronic configuration in (HHH)-[LnFe(L3)3]5+ and 3) the FeII/FeIII oxidation process is prevented by steric constraints. Detailed photophysical studies of (HHH)-[Eu-Zn(L3)3]5+ confirm that the pseudotricapped trigonal-prismatic lanthanide coordination site is not affected by the methyl groups bound to the terminal pyridine, thus leading to significant Eu-centered emission upon UV irradiation. In (HHH)-[EuFe(L3)3]5+, a resonant intramolecular Eu-->Fe(II)hs energy transfer partially quenches the Eu-centered luminescence; however, the residual red emission demonstrates that high-spin iron(II) is compatible with the sensitization of Eu(III) in heterodimetallic d-f complexes. The influence of the electronic configuration of Fe(II) on the efficiency of Eu(III)-->Fe(II) energy-transfer processes is discussed together with its consequence for the design of optically active spin-crossover supramolecular devices.

Journal Article↗
PubMed2003

Mesostructured dye-doped titanium dioxide for micro-optoelectronic applications.

Optically transparent, mesostructured titanium dioxide thin films were fabricated using an amphiphilic poly(alkylene oxide) block copolymer template in combination with retarded hydrolysis of a titanium isopropoxide precursor. Prior to calcination, the films displayed a stable hexagonal mesophase and high refractive indices (1.5 to 1.6) relative to mesostructured silica (1.43). After calcination, the hexagonal mesophase was retained with surface areas > 300 m2 g-1. The dye Rhodamine 6G (commonly used as a laser dye) was incorporated into the copolymer micelle during the templating process. In this way, novel dye-doped mesostructured titanium dioxide films were synthesised. The copolymer not only directs the film structure, but also provides a solubilizing environment suitable for sustaining a high monomer-to-aggregate ratio at elevated dye concentrations. The dye-doped films displayed optical thresholdlike behaviour characteristic of amplified spontaneous emission. Soft lithography was successfully applied to micropattern the dye-doped films. These results pave the way for the fabrication and demonstration of novel microlaser structures and other active optical structures. This new, high-refractive index, mesostructured, dye-doped material could also find applications in areas such as optical coatings, displays and integrated photonic devices.

Journal Article↗
PubMed1985

An accurate laser radiometer for determining visible exposure times.

A laser light radiometer has been developed for the Electro-Optics Branch of the Center for Devices and Radiological Health (CDRH). The radiometer measures direct laser radiation emitted in the visible spectrum. Based upon this measurement, the instrument's microprocessor automatically determines at what time duration the exposure to the measured laser radiation would exceed either the class I accessible emission limits of the Federal Performance Standard for laser products or the maximum permissible exposure limits of laser user safety standards. The instrument also features automatic background level compensation, pulse measurement capability, and self-diagnosis. Measurement of forward surface illumination levels preceding HpD photoradiation therapy is possible.

Computers↗
PubMed1997

[A quality assurance program of simulators in radiation therapy. 2. Extent and results of long-term quality assurance test on a therapy simulator].

BACKGROUND: Since 1990 we follow a quality assurance program with periodical tests of functional performance values of a 16-year-old simulator. MATERIAL AND METHOD: For this purpose we adopted and modified German standards for quality assurance on linear accelerators and international standards elaborated for simulators (International Electrotechnical Commission). The tests are subdivided into daily visual checks (light field indication, optical distance indicator, isocentre-indicating devices, indication of gantry and collimator angles) and monthly and annually tests of relevant simulator parameters. Some important examples demonstrate the small variation of parameters over 6 years: position of the light field centre when rotating the collimator, diameter of the isocentre circle when rotating the gantry, accuracy of the isocentre indication device, and coincidence of light field and simulated radiation field. RESULTS: As an important result we can state, that by these rigid periodic tests it was possible to detect and compensate deteriorations of simulators quality rapidly. CONCLUSIONS: Technical improvements and specific calling-in of maintenance personnel whenever felt appropriate provided performance characteristics of our old simulator which are required by international recommendations as a basis for modern radiotherapy.

Germany↗
PubMed1996

Measurement of the sperm motility index via the sperm quality analyzer and its relationship to other qualitative sperm parameters.

Sperm parameters such as the concentration and percentage of motile spermatozoa are commonly used to assess semen quality. The sperm quality analyzer (SQA) is a device that detects variations in the optical density of motile spermatozoa, providing a sperm motility index (SMI) that is based on various sperm parameters including the concentration, morphology and acrosomal status of motile spermatozoa. The relationship between SMI values of frozen-thawed bovine spermatozoa undergoing swelling in a hypoosmotic medium (100 mOsm/L) and other sperm parameters were evaluated. Frozen semen specimens from 3 bulls were thawed and washed with Ham's F-10 supplemented with 3% BSA and split into 3 (0.2 mL) aliquots. The aliquots were diluted with 1.0 mL of Ham's F-10 (Aliquot 1), isotonic sodium citrate (Aliquot 2), and hypotonic sodium citrate (Aliquot 3). The osmotic pressure of the media used for dilution of Aliquots 1 and 2 was 300 mOsm/L, while that for Aliquot 3 was 100 mOsm/L. Following dilution, the aliquots were incubated for 30 min and manually assessed at 5-min intervals for the percentage and grade of motility (Grades 0 to 4) as well as for the percentage of swollen spermatozoa. Sperm samples were simultaneously evaluated by SQA to obtain the SMI values at the same 5-min intervals during the 30-min incubation. Significant correlations were observed between SMI values and other sperm parameters in Aliquot 3 (P < 0.05). The results indicated that the SMI values obtained from frozen-thawed bovine spermatozoa exposed to a 100 mOsm/L diluent, which causes optimal swelling of spermatozoa, are highly correlated to other sperm parameters. The SQA unit, as applied in this study, can be used for rapid and reliable screening of sperm samples.

Journal Article↗
PubMed1995

Electrical resistance measurements on cerebral capillary endothelial cells--a new technique to study small surface areas.

We present a new method which allows resistance measurements in selected cell monolayer areas with a size of less than one mm2. Up to now cell-covered macroscopic filters with areas up to 5 cm2 have been used giving reliable results only in the absence of inhomogeneities or contaminating cells. The new measuring device is posed on the microscope optic to allow an optical characterization of the measuring area and enables us to scan the cell-covered filter. This method has been applied to determine a reversible modulation of the tightness of intercellular contacts between epithelial or endothelial cells in culture. Tight junction resistance is modulated by Ca2+ and basic amino acids in cultured porcine cerebral microvascular endothelial cells that represent the blood-brain barrier.

Animals↗
PubMed2002

Devic's neuromyelitis optica: clinical, laboratory, MRI and outcome profile.

Devic's neuromyelitis optica (NMO) associates optic neuritis and myelitis without any other neurological signs. Many patients with NMO may be diagnosed as having multiple sclerosis (MS), optic neuritis and myelitis being the inaugural symptom in 20% and 5% of MS cases, respectively. The aim of our study was to compare a new NMO cohort with recent studies and to try to determine the place of NMO in the spectrum of MS. We retrospectively studied 13 patients with a complete diagnostic workup for NMO. We compared our data with the most recent studies on NMO and with the criteria proposed by Wingerchuck et al. [Neurology 53 (1999) 1107]. We also determined whether these patients fulfilled the diagnostic criteria for MS. Thirteen patients (10 women and three men, with a mean age of 37.4 years) were included in the study. We found similar results to previously published data, except for an association with vasculitis in 38% of our cases. All but three of the patients fulfilled the clinical criteria for MS and two patients fulfilled both clinical and MRI criteria for MS. However, if we applied more restrictive criteria concerning spinal cord and brain MRI and CSF, none of our NMO patients fulfilled the MS diagnostic criteria. NMO might therefore be differentiated from MS by the application of more stringent criteria. Furthermore, all NMO patients should be investigated for vasculitis, even those with no history of systemic disease.

Adrenal Cortex Hormones↗
PubMed1998

Biological response to a synthetic cornea.

We have designed a synthetic cornea that has a transparent hydrogel optic and a porous skirt. The device has been implanted in rabbit corneas. We have shown that keratocytes migrate into the device and deposit a complex extracellular matrix. The immediate response is detected in the surrounding stroma, and the secondary response is seen after cells have deposited a matrix in the disc. After implantation, a decrease in keratan sulfate accompanied by an increase in dermatan sulfate was detected in the surrounding tissue compared to the unwounded corneal stroma. The glycosaminoglycans in the disc resemble that of an injured stroma. The appearance of heparan sulfate and growth factors, bFGF and TGFbeta, was not detected until 6 weeks after implantation. The growth factors were detected at the interface between the device and the tissue and become more diffuse over time. Methods of controlled release in vivo were used to enhance the rate of fibroplasia and wound repair. While these were successful in the cornea itself, when combined with the synthetic cornea the response was magnified and the initial attempts yielded neovascularization and edema. Currently, efforts are being directed at controlling the release within the porous haptic so that fibroplasia is enhanced while minimizing an inflammatory response.

Animals↗
PubMed2002

Multiple fiber-optic dual-beam UV/Vis system with application to dissolution testing.

A system for fiber-optic probing in dissolution testing of solid pharmaceutical formulations has been constructed. The system is based on an imaging spectrometer and a charged coupled device (CCD) detector and includes 12 fiber-optic probes with a novel dual-path design. UV light was produced by a small arc deuterium lamp illuminating an optical fiber bundle. Twelve fiber-optic dipping probes were constructed with a reflection geometry. A 5 mm diameter lens was used to achieve a parallel light beam. The light passed back and forth through the flow-through cuvette defined by a sapphire window and a coated aluminium mirror. The mirror was cut in half and each segment was tilted and set at different distances from the window to obtain two separate paths with different lengths. Two receiver fibers were used for each probe to collect the transmitted light. The 24 receiver fibers from the 12 probes were bunched to a linear bundle and fed to an imaging spectrometer and the corresponding spectra were detected with a 512 x 512 pixel cooled CCD detector. The sampling interval was typically a few seconds for all probes. A software package was developed for data recording and on-line analysis. The program includes tools for multi-component analysis. The system was tested for different tablet formulations. Prednisone 50 mg tablets, normally used for control tests of dissolution baths, were followed for 3 h. Secondly, an extended release low dosage tablet was followed for 7 h resulting in a linear dissolution profile. Finally, a combination tablet containing two active drugs was tested for 60 min profiles. In the latter case, separate dissolution curves for the two active components were obtained. Future work will mainly focus on further development of the multi-component capability of the system.

Chemistry, Pharmaceutical↗
PubMed2002

Comparison of the pupil card and pupillometer in measuring pupil size.

PURPOSE: To determine the difference in pupil size measured with the Colvard pupillometer in mesopic and scotopic luminance and with the Rosenbaum pupil card in mesopic luminance between 2 examiners. SETTING: Michel Pop Clinics, Montreal, Quebec, Canada. METHODS: Two examiners used the Colvard pupillometer and the Rosenbaum card to measure pupil size in 58 eyes. The Colvard pupillometer was used in mesopic and scotopic light conditions. The Rosenbaum card was used in mesopic luminance only. Pupil size was evaluated with a 1.0 mm interval scale at the nearest half millimeter. RESULTS: For the 3 sets of data, the limits of agreement and coefficient of interrater repeatability were calculated and a 2 x 2 factorial analysis of variance was performed. Because of interexaminer bias, measurements done in mesopic luminance with the Rosenbaum card were not statistically different from those with the Colvard pupillometer in scotopic luminance, although interrater repeatability of the Colvard pupillometer (0.8 mm) was superior to that of the Rosenbaum card (1.3 mm). CONCLUSIONS: Examiner bias was the greatest statistical bias in all sets of measures. Surgeons may want to opt for a "safe" limit of pupil size (ie, 0.5 to 0.8 mm greater than the measured size) when calculating optical zones in refractive surgery. Future devices for pupil measurement should be based on automatic adjustment sizing.

Diagnostic Techniques, Ophthalmological↗
PubMed2000

The synthesis of metoprolol monitored using Raman spectroscopy and chemometrics.

The synthesis of Metoprolol base was studied using Raman spectroscopy with a 785-nm laser, optical fibres, a holographic transmission grating, confocal optics and a charge-coupled device (CCD) detector. The reaction mixture was heated according to a temperature gradient and spectra of the reaction mixture were obtained by focusing the laser beam through ordinary reaction flasks. Because of overlapping bands, multivariate techniques such as principal components analysis (PCA) and partial least-squares projections to latent structures (PLS) were used in the evaluation of the obtained spectra. The use of PCA or PLS against time does not require any calibration samples and a quantitative calibration is not necessary in order to monitor the reaction. A method for reaction endpoint determination, based on euclidean distances in the score space, is presented. The use of multivariate batch control charts have been demonstrated and a number of problems and solutions regarding the sample presentation have been discussed. The effect of spectral pretreatment on the multivariate results is shown and discussed. The monitoring results show that the time to produce Metoprolol base could be reduced.

Antihypertensive Agents↗
PubMed2003

A two-person technique for fiberscope-aided tracheal extubation/reintubation in intensive care unit (ICU) patients.

The technique of fiberoptic-aided intubation for management of a difficult airway is often limited in the presence of blood or secretions and conditions in which the passage of a fiberoptic bronchoscope ("fiberscope") beneath the epiglottis and into the glottic opening may prove difficult. Direct laryngoscopy can be utilized in combination with the fiberscope as a two-person technique to overcome these challenges. We report the usefulness of a two-person technique using the flexible fiberscope in combination with direct laryngoscopy for extubation/reintubation in two intensive care unit patients with known difficult airways.

Adult↗