Nephelometry and Turbidimetry
Lasers
Automated homogeneous immunoassay for gentamicin on the dimension clinical chemistry system. (1/1003)
BACKGROUND: Monitoring of the concentration of gentamicin in serum and plasma during therapy is widely recommended and practiced in hospitals. Our aim was to develop a homogeneous immunoassay based on particle-enhanced turbidimetric inhibition immunoassay technology to quantify gentamicin on the Dimension clinical chemistry system. METHODS: Assay performance was assessed on each of the Dimension models in a 15-instrument interlaboratory comparison study. A split-sample comparison (n = 1171) was also performed between the gentamicin methods on the Dimension system and the Abbott TDx analyzer, using multiple reagent and calibrator lots on multiple instruments. RESULTS: The Dimension method was linear to 25.1 micromol/L (12.0 microg/mL) with a detection limit of 0.63 micromol/L (0.3 microg/mL). Calibration was stable for 30 days. The within-run imprecision (CV) was <1.3%, and total imprecision ranged from 1.8% to 3.2% between 4.2 micromol/L (2.0 microg/mL) and 16.7 micromol/L (8.0 microg/mL) gentamicin. Linear regression analysis of the results on the Dimension method (DM) vs the Abbott TDx yielded the following equation: DM = 0.98TDx - 0.42; r = 0.987. Minimal interference was observed from structurally related compounds such as sagamicin, netilmicin, and sisomicin. CONCLUSION: The monoclonal antibody used in this method has similar reactivities toward the individual gentamicin subspecies C1, C1a, and C2, thus providing analytical recovery not significantly dependent on relative subspecies concentrations. (+info)Recombinant human type II collagens with low and high levels of hydroxylysine and its glycosylated forms show marked differences in fibrillogenesis in vitro. (2/1003)
Type II collagen is the main structural component of hyaline cartilages where it forms networks of thin fibrils that differ in morphology from the much thicker fibrils of type I collagen. We studied here in vitro the formation of fibrils of pepsin-treated recombinant human type II collagen produced in insect cells. Two kinds of type II collagen preparation were used: low hydroxylysine collagen having 2.0 hydroxylysine residues/1,000 amino acids, including 1.3 glycosylated hydroxylysines; and high hydroxylysine collagen having 19 hydroxylysines/1,000 amino acids, including 8.9 glycosylated hydroxylysines. A marked difference in fibril formation was found between these two kinds of collagen preparation, in that the maximal turbidity of the former was reached within 5 min under the standard assay conditions, whereas the absorbance of the latter increased until about 600 min. The critical concentration with the latter was about 10-fold, and the absorbance/microgram collagen incorporated into the fibrils was about one-sixth. The morphology of the fibrils was also different, in that the high hydroxylysine collagen formed thin fibrils with essentially no interfibril interaction or aggregation, whereas the low hydroxylysine collagen formed thick fibrils on a background of thin ones. The data thus indicate that regulation of the extents of lysine hydroxylation and hydroxylysine glycosylation may play a major role in the regulation of collagen fibril formation and the morphology of the fibrils. (+info)Human African trypanosomiasis: a latex agglutination field test for quantifying IgM in cerebrospinal fluid. (3/1003)
LATEX/IgM, a rapid agglutination test for the semi-quantitative detection of IgM in cerebrospinal fluid of patients with African trypanosomiasis, is described in this article. The lyophilized reagent has been designed for field use and remains stable at 45 degrees C for one year. The test has been evaluated on cerebrospinal fluid samples from trypanosome-infected and non-infected patients, by comparison with commercial latex agglutination, radial immunodiffusion, and nephelometry. All test systems yielded similar results. (+info)cAMP-mediated catabolite repression and electrochemical potential-dependent production of an extracellular amylase in Vibrio alginolyticus. (4/1003)
Vibrio alginolyticus, a halophilic marine bacterium, produced an extracellular amylase with a molecular mass of approximately 56,000, and the amylase appeared to be subject to catabolite repression mediated by cAMP. The production of amylase at pH 6.5, at which the respiratory chain-linked H+ pump functions, was inhibited about 75% at 24 hours following the addition of 2 microM carbonyl cyanide m-chlorophenylhydrazone (CCCP), while the production at pH 8.5, at which the respiratory chain-linked Na+ pump functions, was only slightly inhibited by the addition of 2 microM CCCP. In contrast, the production of amylase in a mutant bacterium defective in the Na+ pump was almost completely inhibited even at pH 8.5 as well as pH 6.5 by the addition of 2 microM CCCP. (+info)Self-aggregation of DNA oligomers with XGG trinucleotide repeats: kinetic and atomic force microscopy measurements. (5/1003)
Turbidity measurements via absorbance monitoring at 320 nm were employed to obtain autocatalytic-like kinetic profiles of K+-induced aggregate formation of d(XGG)4 and some related oligomers, where X = A, C, G, and T. At least 1 M KCl is needed to observe the turbidity-measurable aggregation at pH 8, and the relative propensity for aggregate formation is shown to follow the order d(GGG)4 > d(AGG)4 approximately d(TGG)4 >> d(CGG)4. The presence of Mg2+ greatly facilitates and dramatically reduces the amount of K+ required to initiate aggregation and significantly enhances the thermal stabilities of the aggregates. Replacement of K+ by Na+ fails to induce a similar phenomenon. The Psi-type CD characteristics of aggregates are strongly dependent on the sequence and ionic conditions. Despite their ease of aggregate formation, oligomers with AGG trinucleotide repeats fail to exhibit Psi-CD formation. The propensity for aggregation is greatly affected by the chain length, with oligomers of four repeats being most facile. Appending X base at the 3' end of d(GGXGGXGGXGG) appears to provide a greater hindrance to aggregation than at the 5' end. Atomic force microscopic images support some of these findings and reveal the morphologies of these aggregates. The presence of MgCl2 in solutions appears to considerably elongate the K+-induced aggregates. (+info)Interaction of an exchangeable apolipoprotein with phospholipid vesicles and lipoprotein particles. Role of leucines 32, 34, and 95 in Locusta migratoria apolipophorin III. (6/1003)
Apolipophorin III (apoLp-III) from Locusta migratoria is an exchangeable apolipoprotein that binds reversibly to lipid surfaces. In the lipid-free state this 164-residue protein exists as a bundle of five elongated amphipathic alpha-helices. Upon lipid binding, apoLp-III undergoes a significant conformational change, resulting in exposure of its hydrophobic interior to the lipid environment. On the basis of x-ray crystallographic data (Breiter, D. R., Kanost, M. R., Benning, M. M., Wesenberg, G., Law, J. H., Wells, M. A., Rayment, I., and Holden, H. M. (1991) Biochemistry 30, 603-608), it was proposed that hydrophobic residues, present in loops that connect helices 1 and 2 (Leu-32 and Leu-34) and helices 3 and 4 (Leu-95), may function in initiation of lipid binding. To examine this hypothesis, mutant apoLp-IIIs were designed wherein the three Leu residues were replaced by Arg, individually or together. Circular dichroism spectroscopy and temperature and guanidine hydrochloride denaturation studies showed that the mutations did not cause major changes in secondary structure content or stability. In lipid binding assays, addition of apoLp-III to phospholipid vesicles caused a rapid clearance of vesicle turbidity due to transformation to discoidal complexes. L34R and L32R/L34R/L95R apoLp-IIIs displayed a much stronger interaction with lipid vesicles than wild-type apoLp-III. Furthermore, it was demonstrated that the mutant apoLp-IIIs retained their ability to bind to lipoprotein particles. However, in lipoprotein competition binding assays, the mutants displayed an impaired ability to initiate a binding interaction when compared with wild-type apoLp-III. The data indicate that the loops connecting helices 1 and 2 and helices 3 and 4 are critical regions in the protein, contributing to recognition of hydrophobic defects on lipoprotein surfaces by apoLp-III. (+info)Multiple clinic and home blood pressure measurements versus ambulatory blood pressure monitoring. (7/1003)
To compare multiple clinic and home blood pressure (BP) measurements and ambulatory BP monitoring in the clinical evaluation of hypertension, we studied 239 middle-aged pharmacologically untreated hypertensive men and women who were referred to the study from the primary healthcare provider. Ambulatory BP monitoring was successfully completed for 233 patients. Clinic BP was measured by a trained nurse with a mercury sphygmomanometer and averaged over 4 duplicate measures. Self-recorded home BP was measured with a semiautomatic oscillometric device twice every morning and twice every evening on 7 consecutive days. Ambulatory BP was recorded with an auscultatory device. Two-dimensionally controlled M-mode echocardiography was successfully performed on 232 patients. Twenty-four-hour urinary albumin was determined by nephelometry. Clinic BP was 144.5+/-12.6/94.5+/-7.4 mm Hg, home BP (the mean of 14 self-recorded measures) was 138.9+/-13.1/92.9+/-8.6 mm Hg, home morning BP (the mean of the first 4 duplicate morning measures) was 137.1+/-13.7/92.4+/-9.2 mm Hg, daytime ambulatory BP was 148.3+/-13. 9/91.9+/-7.8 mm Hg, nighttime ambulatory BP was 125.5+/-16.4/75. 6+/-8.9 mm Hg, and 24-hour ambulatory BP was 141.7+/-14.0/87.2+/-7.6 mm Hg. Pearson correlation coefficients of clinic, home, home morning, and daytime ambulatory BPs to albuminuria and to the characteristics of the left ventricle were nearly equal. In multivariate regression analyses, 36% (P<0.0001) of the cross-sectional variation in left ventricular mass index was attributed to gender and home morning systolic BP in models that originally included age, gender, and clinic, self-measured home morning, and ambulatory daytime, nighttime, and 24-hour systolic and diastolic BPs. We concluded that carefully controlled nonphysician-measured clinic and self-measured home BPs, when averaged over 4 duplicate measurements, are as reliable as ambulatory BP monitoring in the clinical evaluation of untreated hypertension. (+info)McFarland nephelometer as a simple method to estimate the sensitivity of the polymerase chain reaction using Mycobacterium tuberculosis as a research tool. (8/1003)
Polymerase chain reaction (PCR) has been widely investigated for the diagnosis of tuberculosis. However, before this technique is applied on clinical samples, it needs to be well standardized. We describe the use of McFarland nephelometer, a very simple approach to determine microorganism concentration in solution, for PCR standardization and DNA quantitation, using Mycobacterium tuberculosis as a model. Tuberculosis is an extremely important disease for the public health system in developing countries and, with the advent of AIDS, it has also become an important public health problem in developed countries. Using Mycobacterium tuberculosis as a research model, we were able to detect 3 M. tuberculosis genomes using the McFarland nephelometer to assess mycobacterial concentration. We have shown here that McFarland nephelometer is an easy and reliable procedure to determine PCR sensitivity at lower costs. (+info)Nephelometry and turbidimetry are methods used in clinical laboratories to measure the amount of particles, such as proteins or cells, present in a liquid sample. The main difference between these two techniques lies in how they detect and quantify the particles.
1. Nephelometry: This is a laboratory method that measures the amount of light scattered by suspended particles in a liquid medium at a 90-degree angle to the path of the incident light. When light passes through a sample containing particles, some of the light is absorbed, while some is scattered in various directions. In nephelometry, a light beam is shone into the sample, and a detector measures the intensity of the scattered light at a right angle to the light source. The more particles present in the sample, the higher the intensity of scattered light, which correlates with the concentration of particles in the sample. Nephelometry is often used to measure the levels of immunoglobulins, complement components, and other proteins in serum or plasma.
2. Turbidimetry: This is another laboratory method that measures the amount of light blocked or absorbed by suspended particles in a liquid medium. In turbidimetry, a light beam is shone through the sample, and the intensity of the transmitted light is measured. The more particles present in the sample, the more light is absorbed or scattered, resulting in lower transmitted light intensity. Turbidimetric measurements are typically reported as percent transmittance, which is the ratio of the intensity of transmitted light to that of the incident light expressed as a percentage. Turbidimetry can be used to measure various substances, such as proteins, cells, and crystals, in body fluids like urine, serum, or plasma.
In summary, nephelometry measures the amount of scattered light at a 90-degree angle, while turbidimetry quantifies the reduction in transmitted light intensity due to particle presence. Both methods are useful for determining the concentration of particles in liquid samples and are commonly used in clinical laboratories for diagnostic purposes.
"Autoanalysis" is not a term that is widely used in the medical field. However, in psychology and psychotherapy, "autoanalysis" refers to the process of self-analysis or self-examination, where an individual analyzes their own thoughts, feelings, behaviors, and experiences to gain insight into their unconscious mind and understand their motivations, conflicts, and emotional patterns.
Self-analysis can involve various techniques such as introspection, journaling, meditation, dream analysis, and reflection on past experiences. While autoanalysis can be a useful tool for personal growth and self-awareness, it is generally considered less reliable and comprehensive than professional psychotherapy or psychoanalysis, which involves a trained therapist or analyst who can provide objective feedback, interpretation, and guidance.
A laser is not a medical term per se, but a physical concept that has important applications in medicine. The term "LASER" stands for "Light Amplification by Stimulated Emission of Radiation." It refers to a device that produces and amplifies light with specific characteristics, such as monochromaticity (single wavelength), coherence (all waves moving in the same direction), and high intensity.
In medicine, lasers are used for various therapeutic and diagnostic purposes, including surgery, dermatology, ophthalmology, and dentistry. They can be used to cut, coagulate, or vaporize tissues with great precision, minimizing damage to surrounding structures. Additionally, lasers can be used to detect and measure physiological parameters, such as blood flow and oxygen saturation.
It's important to note that while lasers are powerful tools in medicine, they must be used by trained professionals to ensure safe and effective treatment.
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List of MeSH codes (E05)
Turbidimetry
Assay
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Immunofluorescence1
- Clinical Immunoassay is a branch of chemistry that involves measuring serum proteins using immunological methods such as nephelometry, turbidimetry, immunoassay, immunofluorescence, and chemiluminescence. (imvinfo.com)
ELISA1
- We are specialised in both the use of virtually all available systems of detection, including enzymatic, colorimetric, fluorescent and quimioluminescent systems, and also in all types of solid phase and liquid phase technologies,such as ELISA, Turbidimetry, Nephelometry and Cytometry, amongst others. (gen.tr)
Serum1
- The challenge of this serum testing is the heterogeneity of free light chains and other methodical issues of testing which challenge in particular FLC tests based on turbidimetry and nephelometry. (sebia.com)
Photometry1
- With these photometers or modules you will be able to measure photometry, tubidimetry, nephelometry and fluorescence in the same system and simultaneously. (labnet-optics.com)
Colloidal1
- Nephelometry :- It is deals with analysis of colloidal system. (gpatindia.com)
Intensity2
- In turbidimetry, the intensity of light transmitted through the medium, the unscattered light, is measured. (lookformedical.com)
- In nephelometry, the intensity of the scattered light is measured, usually, but not necessarily, at right angles to the incident light beam. (lookformedical.com)
Measurement1
- b) turbidimetry, procedure for measurement of the attenuation of a radiant flux, more applicable to highly turbid waters (for example waste waters or other cloudy waters). (iso.org)
Real-time1
- Personal PM 2.5 nephelometry was used to estimate 24-h individual-level real-time PM 2.5 exposures. (psu.edu)
Immunoglobulin1
- One of the most commonly used approach is to measure total concentration of immunoglobulin (Ig) isotype involved in monoclonal synthesis (Ig invl ) using turbidimetry or nephelometry. (biochemia-medica.com)
Descriptor1
- Nephelometry and Turbidimetry" is a descriptor in the National Library of Medicine's controlled vocabulary thesaurus, MeSH (Medical Subject Headings) . (childrensmercy.org)