Asymmetric division ofHansenula polymorphareflected by a drop of light scatter intensity measured in batch microtiter plate cultivations at phosphate limitation

2009 ◽  
Vol 104 (3) ◽  
pp. 554-561 ◽  
Author(s):  
Kirsten Kottmeier ◽  
Jost Weber ◽  
Carsten Müller ◽  
Thomas Bley ◽  
Jochen Büchs
Keyword(s):  
Asymmetric Division ◽  
Microtiter Plate ◽  
Phosphate Limitation ◽  
Light Scatter ◽  
Scatter Intensity

scholarly journals Contamination-resistant, rapid emulsion-based isothermal nucleic acid amplification with Mie-scatter inspired light scatter analysis for bacterial identification

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alexander S. Day ◽  
Tiffany-Heather Ulep ◽  
Elizabeth Budiman ◽  
Laurel Dieckhaus ◽  
Babak Safavinia ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Nucleic Acid Amplification ◽  
Nucleic Acid Detection ◽  
Light Scatter ◽  
Emulsion Droplets ◽  
Assay Performance ◽  
Bacterial Adsorption ◽  
Scatter Intensity ◽  
The Impact ◽  
Theory Light

AbstractAn emulsion loop-mediated isothermal amplification (eLAMP) platform was developed to reduce the impact that contamination has on assay performance. Ongoing LAMP reactions within the emulsion droplets cause a decrease in interfacial tension, causing a decrease in droplet size, which results in decreased light scatter intensity due to Mie theory. Light scatter intensity was monitored via spectrophotometers and fiber optic cables placed at 30° and 60°. Light scatter intensities collected at 3 min, 30° were able to statistically differentiate 103 and 106 CFU/µL initial Escherichia coli O157:H7 concentrations compared to NTC (0 CFU/µL), while the intensity at 60° were able to statistically differentiate 106 CFU/µL initial concentrations and NTC. Control experiments were conducted to validate nucleic acid detection versus bacterial adsorption, finding that the light scatter intensities change is due specifically to ongoing LAMP amplification. After inducing contamination of bulk LAMP reagents, specificity lowered to 0% with conventional LAMP, while the eLAMP platform showed 87.5% specificity. We have demonstrated the use of angle-dependent light scatter intensity as a means of real-time monitoring of an emulsion LAMP platform and fabricated a smartphone-based monitoring system that showed similar trends as spectrophotometer light scatter data, validating the technology for a field deployable platform.

scholarly journals DEVELOPMENT OF OPTICAL TRANSDUCER ON FABRICS FOR THE APPLICATION OF LIQUID CLUSTERING USING REFLECTANCE SPECTROSCOPY

2021 ◽  
Vol 5 (2) ◽  
Author(s):  
Viona Hazar Briliana ◽  
Totok Mujiono
Keyword(s):  
Light Source ◽  
Monochromatic Light ◽  
Reflectance Spectroscopy ◽  
Wearable Device ◽  
Light Scatter ◽  
Optic System ◽  
Pca Method ◽  
The Difference ◽  
Scatter Intensity ◽  
Optical Transducer

Recently, usage of fabrics as wearable device, along with their applications are increasing, one example being the detection of bio-analyzes such as blood or sweat. One method used to observe the properties of the material of a fabric is to use the Refcletance Spectroscopy, in which excitation of monochromatic light with a specific wavelength is given to a fabrics. Intensity value is then processed using the PCA method in order to obtain the pattern of the difference between each substrate. The proposed transducer optic system consists of 405nm blueviolet laser as the light source, biconvex lens, Adafruit AS7262 light detector, and Arduino. This system can only detect the difference in substrate content from the occurring light scatter. This system can be applied to various kinds of fabric wearable material with differing scatter intensity values depending on the kind of fabrics. Softer kind of fabric is proposed as material for the wearable device because it gives a high scatter intensity value and constant values in every repetation which results in better data reading.Keywords: clustering, optical, reflectance, spectroscopy, transducer, wearable.

The role of light scatter in the residual visual sensitivity of patients with complete cerebral hemispherectomy

1996 ◽  
Vol 13 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Sheila M. King ◽  
Paul Azzopardi ◽  
Alan Cowey ◽  
John Oxbury ◽  
Susan Oxbury
Keyword(s):  
Visual Information ◽  
Visual Cues ◽  
Scattered Light ◽  
Visual Sensitivity ◽  
Light Scatter ◽  
Moving Targets ◽  
Oculomotor Responses ◽  
Scatter Intensity ◽  
Role Of Light

AbstractVarious residual visual capacities have been reported for the phenomenally blind field of hemispherectomized patients, providing evidence for the relative roles of cortical and subcortical pathways in vision. We attempted to characterize these functions by examining the ability of five patients to detect, localize, and discriminate high-contrast flashed, flickering and moving targets. Dependent measures were verbal, manual, and oculomotor responses. As a control for light scatter, intensity thresholds for monocular detection of targets in the hemianopic field were compared with thresholds obtained when using an additional half eyepatch to occlude the blind hemiretina of the tested eye. One unilaterally destriate patient was tested on the same tasks. In photopic conditions, none of the hemispherectomized patients could respond to visual cues in their impaired fields, whereas the destriate patient could detect, discriminate, and point to targets, and appreciate the apparent motion of stimuli across his midline. Under reduced lighting, the threshold luminance required by hemispherectomized patients to detect stimuli presented monocularly was similar to that required for their detection when all visual information was occluded in the blind field, and only available to the visual system indirectly via light scatter. In contrast, the destriate patient's monocular threshold in his blind field was substantially lower than that for stimuli directly occluded in the blind field. As we found no range of stimuli which the hemispherectomized patients could detect or discriminate that was not also associated with discriminable scattered light, we conclude that the subcortical pathways which survive hemispherectomy cannot mediate voluntary behavioural responses to visual information in the hemianopic field.

Specific Protein Analysis by Light-Scatter Measurement with a Miniature Centrifugal Fast Analyzer

1974 ◽  
Vol 20 (8) ◽  
pp. 1055-1061 ◽  
Author(s):  
T O Tiffany ◽  
J M Parella ◽  
W F Johnson ◽  
C A Burtis
Keyword(s):  
Polyethylene Glycol ◽  
Protein Analysis ◽  
Specific Protein ◽  
Light Scatter ◽  
Reaction Conditions ◽  
Rate Of Reaction ◽  
Scatter Intensity ◽  
Polyethylene Glycol 6000 ◽  
Apparent Equilibrium

Abstract A miniature Centrifugal Fast Analyzer has been modified for fluorescence and light-scatter measurements by using several rotors developed for this purpose. The modified system has been used to evaluate the feasibility of adapting specific protein analyses, such as IgG, IgA, IgM, C'3 complement component, and α-1-antitrypsin, to the Centrifugal Fast Analyzer. A study of reaction conditions has revealed that the addition of polyethylene glycol 6000 (Carbowax) to the dilution medium increases the rate of reaction and allows apparent equilibrium to be achieved in less than 60 s. Furthermore, scatter intensity is enhanced. This system can be used to make rapid immunoglobulin measurements with only microliter volumes of antibody (2-7 µl), without the need of sample blanks. Determination of antigen excess by a method that involves dynamic injection of antibody is also discussed.

scholarly journals Determination of the Biomasses of Small Bacteria at Low Concentrations in a Mixture of Species with Forward Light Scatter Measurements by Flow Cytometry

1998 ◽  
Vol 64 (10) ◽  
pp. 3900-3909 ◽  
Author(s):  
B. R. Robertson ◽  
D. K. Button ◽  
A. L. Koch
Keyword(s):  
Flow Cytometry ◽  
Buoyant Density ◽  
Cell Mass ◽  
Dry Weight ◽  
Dry Mass ◽  
Coulter Counter ◽  
Acetate Incorporation ◽  
Light Scatter ◽  
Standard Curve ◽  
Scatter Intensity

ABSTRACT The forward light scatter intensity of bacteria analyzed by flow cytometry varied with their dry mass, in accordance with theory. A standard curve was formulated with Rayleigh-Gans theory to accommodate cell shape and alignment. It was calibrated with an extinction-culture isolate of the small marine organism Cycloclasticus oligotrophus, for which dry weight was determined by CHN analysis and 14C-acetate incorporation. Increased light scatter intensity due to formaldehyde accumulation in preserved cells was included in the standard curve. When differences in the refractive indices of culture media and interspecies differences in the effects of preservation were taken into account, there was agreement between cell mass obtained by flow cytometry for various bacterial species and cell mass computed from Coulter Counter volume and buoyant density. This agreement validated the standard curve and supported the assumption that cells were aligned in the flow stream. Several subpopulations were resolved in a mixture of three species analyzed according to forward light scatter and DNA-bound DAPI (4′,6-diamidino-2-phenylindole) fluorescence intensity. The total biomass of the mixture was 340 μg/liter. The lowest value for mean dry mass, 0.027 ± 0.008 pg/cell, was for the subpopulation of C. oligotrophuscontaining cells with a single chromosome. Calculations from measurements of dry mass, Coulter Counter volume, and buoyant density revealed that the dry weight of the isolate was 14 to 18% of its wet weight, compared to 30% for Escherichia coli. The method is suitable for cells with 0.005 to about 1.2 pg of dry weight at concentrations of as low as 103 cells/ml and offers a unique capability for determining biomass distributions in mixed bacterial populations.

A Sensitive and Facile Assay for the Measurement of Activated Protein C Activity Levels in Vivo

1993 ◽  
Vol 69 (05) ◽  
pp. 441-447 ◽  
Author(s):  
Carolyn L Orthner ◽  
Billy Kolen ◽  
William N Drohan
Keyword(s):  
Protein C ◽  
Plasma Concentrations ◽  
Limited Proteolysis ◽  
Activated Protein C ◽  
Microtiter Plate ◽  
Reversible Inhibitor ◽  
Activity Levels ◽  
Standard Curve ◽  
Agarose Beads

SummaryActivated protein C (APC) is a serine protease which plays an important role as a naturally occurring antithrombotic enzyme. APC, which is formed by thrombin-catalyzed limited proteolysis of the zymogen protein C, functions as an anticoagulant by proteolytic inactivation of the coagulation cofactors VIIIa and Va. APC is inhibited by several members of the serpin family as well a by α2-macroglobulin. APC is being developed as a therapeutic for the prevention and treatment of thrombosis. We have developed an assay to quantify circulating levels of enzymatically active APC during its administration to patients, in healthy individuals, and in various disease states. This assay utilizes an EDTA-dependent anti-protein C monoclonal antibody (Mab) 7D7B10 to capture both APC and protein C from plasma, prepared from blood collected in an anticoagulant supplemented with the reversible inhibitor p-aminobenzamidine. Mab 7D7B10-derivatized agarose beads are added to the wells of a 96-well filtration plate, equilibrated with Tris-buffered saline, and incubated for 10 min with 200 μl of plasma. After washing, APC and protein C are eluted from the immunosorbent beads with a calcium-containing buffer into the wells of a 96-well microtiter plate containing antithrombin III (ATIII) and heparin. The amidolytic activity of APC is then measured on a kinetic plate reader following the addition of L-pyroglutamyl-L-prolyl-L-arginine-p-nitroanilide (S-2366) substrate.The rate of substrate hydrolysis was proportional to APC concentration over a 200-fold concentration range (5.0 to 1,000 ng/ml) when measured continuously over a 15 to 30 min time period. The coefficient of variation was 5.9% at 35 ng/ml and 8.8% at 350 ng/ml APC. The sensitivity of the assay could be increased by measuring the amount of color produced after longer incubation times in the endpoint mode. The measured APC activity levels were little affected by varying protein C or prothrombin over the extremes of 0 to 150% of normal plasma concentrations. By constructing the standard curve in protein C-deficient plasma, the concentration of APC activity in normal pooled plasma was determined to be 2.8 ng/ml (45 pM), which represents 0.08% of the protein C concentration. The assay was approximately 50-fold more sensitive than the identical assay, but using Mab-coated microtiter wells rather than immunosorbent beads as the capture step.

Development of 96 Multiple Injection-GC-MS Technique and Its Application in Protein Engineering of Natural and Non-Natural Enzymatic Reactions

2019 ◽  
Author(s):  
Anja Knorrscheidt ◽  
Pascal Püllmann ◽  
Eugen Schell ◽  
Dominik Homann ◽  
Erik Freier ◽  
...  
Keyword(s):  
Microtiter Plate ◽  
Axial Ligand ◽  
Cell System ◽  
Enzymatic Reactions ◽  
The Novel ◽  
Internal Standards ◽  
E Coli ◽  
Enzyme Screening ◽  
Plate Analysis ◽  
Microtiter Plate Analysis

Directed evolution requires the screening of enzyme libraries in biological matrices. Available assays are mostly substrate or enzyme specific. Chromatographic techniques like LC and GC overcome this limitation, but require long analysis times. The herein developed multiple injections in a single experimental run (MISER) using GC coupled to MS allows the injection of samples every 33 s resulting in 96-well microtiter plate analysis within 50 min. This technique is implementable in any GC-MS system with autosampling. Since the GC-MS is far less prone to ion suppression than LCMS, no chromatographic separation is required. This allows the utilisation of an internal standards and the detection of main and side-product. To prove the feasibility of the system in enzyme screening, two libraries were assessed: i) YfeX library in an E. coli whole cell system for the carbene-transfer reaction on indole revealing the novel axial ligand tryptophan, ii) a library of 616 chimeras of fungal unspecific peroxygenase (UPO) in S. cerevisiae supernatant for hydroxylation of tetralin resulting in novel constructs. The data quality and representation are automatically assessed by a new R-script.

Investigate of the Ability of Cronobacter sakazakii Isolated from Clinical Samples of Children Under Two Years to Induce Swimming, Swarming and Biofilm

2018 ◽  
pp. 123
Author(s):  
Luma Abdal Hady Zwein ◽  
Tharieyt Abdulrahman Motlag ◽  
Mohamed Mousa
Keyword(s):  
Cerebrospinal Fluid ◽  
Congo Red ◽  
Biofilm Formation ◽  
Microtiter Plate ◽  
Clinical Samples ◽  
Cronobacter Sakazakii ◽  
Yellow Color ◽  
Golden Yellow ◽  
Vitek 2 ◽  
Biochemical Examination

      The study included 200 samples were collected   from   children  under two   years included (50 samples from each of Cerebrospinal fluid, Blood, Stool and Urine) from, Central Children Hospital and Children's Protections Educational Hospital. Isolates bacterial were obtained cultural, microscopic and biochemical examination and diagnosed to the species by using vitek2 system. The results showed there were contamination in 6.5% of clinical samples. The diagnosed colonies which gave pink color on the MacConkey agar , golden yellow color on the Trypton Soy agar and green color on the Birillent Enterobacter sakazakii agar and gave  a probability of 99% in the vitek 2 and were identified as Cronobacter sakazakii. The identification revealed of thirteen isolates: 6(46.16%) isolated from Cerebrospinal fluid samples, 7(53.84%) isolated from blood samples and not isolated bacteria from stool and urine samples. The results of the investigation of some virulence factors showed that all bacteria isolates were able to swimming with a diameter ranging (1-9 mm) and swarming with a diameter ranging (1-40 mm) and their  ability to biofilm formation  by using three methods. The results show the ability  of  isolates to form biofilm by using  Congo red media  methods where it is 12 (92.30 %) out of 13 isolated bacteria belonging to C. sakazakii  able to form biofilm on the Congo red media  which is 3 (23.07%) were  strong production  biofilm ,   8 (61.53%)  were intermediate  production  biofilm and  1 (7.69% ) were weak  biofilm formation , while the 1 (7.69%)  unable to form biofilm.  Tubes method were all isolates were able to form biofilm, it were found that 3 (23.07%)  isolates strong, and 8 (61.53%) intermediate  and 2( 15.38%)  weak biofilm formation. Microtiter plate method  gave 5 (38.46 %) isolates strong, 6 (46.15%) intermediate and 1 (7.69%) weak biofilm formation.  

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