Laser Nephelometer Research Articles

Investigation of blood cell properties using laser diffractometry and kinetic nephelometry

The portable multi-channel laser nephelometer was developed and applied for quantitative and qualitative researches of blood cells. Obtained findings were analyzed in comparison with results of laser diffractometry and microscopy.

AB0407 Combined serum free light chains are associated with active disease in systemic lupus erythematosus

BackgroundSystemic lupus erythematosus (SLE) is characterised by chronic B cell stimulation and hyperactivity. Due to the complexity and variability observed during the course of SLE, reliable and accurate biomarkers for...

An inexpensive flow-through laser nephelometer for the detection of natural colloids and manufactured nanoparticles

The transport and fate of colloidal particles is coming under increasing scrutiny, largely because of the expected rapid expansion in the production of manufactured nanoparticles and because of possible interactions of natural and manufactured nanoparticles with pollutants. Risk assessments of engineered nanoparticles may only be carried out if means exist to quantify the processes that control the fate of the particles as they interact with materials in the environment. For aqueous systems, there are several analytical methods available that may be utilised to classify and quantify a colloidal suspension but where the particles are of a generally uniform nature, and in sufficient number, the turbidity of the fluid provides an accurate measurement of concentration. In order to investigate the transport of manufactured nanoparticles through small saturated rock columns, a simple and inexpensive laser nephelometer was developed which incorporates a low volume flow-through cell in order to provide a continuous record of the elution of particles from the column. The design, construction and evaluation of the device are presented together with example data. Although designed specifically for the laboratory study of colloid transport through columns, the device may be readily adapted for other purposes in the field or laboratory wherever an inexpensive and robust continuous means of turbidity measurement is required.

Measuring Turbidity in the Laser Age

This article discusses turbidimeter technology advancements that now include laser nephelometers whose detection capabilities approach the functionality of particle counters. Laser nephelometers can detect ultra‐low turbidity changes, as well as filter deterioration and breakthrough. Increasingly, these capabilities allow turbidity and particle‐counting measurements to become complementary technologies. In addition, a laser nephelometer plays two roles at conventional water treatment facilities by providing accurate, on‐line turbidity measurements to meet regulatory reporting requirements and serving as a sensitive, highly accurate process instrument for optimizing filter performance and run times.

Prognostic value of quantitative immune alterations in melanoma patients

• Purpose: The immune response is altered in patients with neoplasms. Immunosuppression has important consequences in patients with melanoma. The aim of this study was to assess quantitative immune alterations in melanoma patients.. • Material and methods: We obtained a peripheral blood sample in EDTA from 86 melanoma patients (63 of them disease-free and 23 with distant disease). Total leukocytes and lymphocytes, B lymphocytes (CD19), types CD3, CD4, CD8 lymphocytes, and NK lymphocytes (CD56) were counted by determining the surface markers by flow cytometry, using a Coulter Epics Elite (Coulter Corp.). IgA, IgG, IgE and IgM were assayed by nephelometric methods employing a Hyland PDQ laser nephelometer. • Results: We found significant differences between disease-free patients and those with active disease with regard to lymphocytes total count (median: 2251.57 vs. 1783.04/mm 3 , p=0.010), NK lymphocytes (CD56) (149.54 vs. 115.2/mm 3 , p=0.016), and IgA levels (241.59 vs. 300.55 mg/dl, p=0.044), when taken as continuous variables. When considering each parameter as a discontinuous variable, only changes in absolute lymphocyte count retained an statistical difference depending on the presence or absence of active disease, 73.9% of the patients with active metastatic disease having a lymphocyte count below 2000 cells/mm 3 versus only 36.5% of the disease-free patients (c2 Pearson=9.476, df=1, p=0.002). The median survival for the 46 patients with absolute lymphocyte count above 2000 cells/mm 3 was 965 days (DF=65.03, IC 95%=792.72-1090.30) versus 441 days (DF=75.61, IC 95%=292.81-589.19) for the 40 patients with absolute lymphocyte count below 2000 cells/mm3 (log rank=4.54, df=1, p=0.0331). • Conclusions: There are significant differences in some lymphocyte populations and IgA levels between patients with metastases and disease-free patients. Melanoma patients with absolute lymphocyte levels above 2000 cells/mm3 have a longer survival than those with a lymphocyte count below 2000 cells/mm 3 .

Urinary cystatin C as a specific marker of tubular dysfunction

Cystatin C (CST3), a strong inhibitor of cysteine proteinases, is freely filtered by the kidney glomerulus and is reabsorbed by the tubules, where it is almost totally catabolized, with the remainder then eliminated in urine. In tubular diseases, it seems sensible to postulate that CST3 degradation would be reduced and consequently an increase in its urinary elimination would be observed. We report here the development of an automatic quantitative assay to measure CST3 concentrations in urine using a Behring N-Latex Cystatin C kit on a BNII laser nephelometer. We tested its clinical relevance on several kidney disease patients. This assay is sensitive (limit of detection 0.008 mg/L) and precise (within- and between-day CVs < 4%). Reference values for freshly collected urine samples range from 0.03 to 0.18 mg/L. Mean urine CST3 concentrations obtained from 52 patients with kidney tubular disease (4.31 +/- 3.85 mg/L) were significantly higher than those for 60 controls (0.096 +/- 0.044 mg/L; p < 0.0001) and 47 glomerular disease patients (0.106 +/- 0.133 mg/L; p < 0.0001). Increased urinary CST3 concentrations allow the accurate detection of tubular dysfunction among pure and mixed nephropathies. Because of its ability to be processed on automated clinical chemistry analyzers, this assay could easily be used as an adjunct to the standard panel used to screen kidney pathologies, even in emergency situations.

Circulating immune complexes in various forms of Behçet's disease.

The etiology of Behçet's disease (BD) is uncertain but there is strong evidence that the immune system is implicated in its pathogenesis. We assessed circulating immune complexes (CIC) in peripheral blood of 34 patients with BD, forming eight clinical groups, using a laser nephelometer to obtain more insight in the pathogenesis of different clinical forms of BD. Twenty healthy controls and eight patients with recurrent oral ulcerations were also included in the study. Levels of CIC were significantly higher in patients (1.83 +/- 0.93 microgram/mL) than in controls (0.84 +/- 0.51 microgram/mL; P < 0.001). High titers were found in the groups of patients with erythema nodosum (3.14 +/- 0.44 microgram/mL), neurologic manifestations (2.9 +/- 0.58 microgram/mL), and ocular manifestations (2.34 +/- 0.93 microgram/mL). Compared to patients with recurrent oral ulcerations (1.91 +/- 0.77 microgram/mL), the mean value of CIC in patients with BD did not differ significantly, but the groups of patients having erythema nodosum, positive pathergy, and neurologic manifestations had significantly higher levels (P < 0.05) and the group of patients at the mild end of the spectrum (group 8) had a significantly lower level (1.09 +/- 0.41 microgram/mL) (P < 0.05). Only the groups having erythema nodosum, positive pathergy, and neurologic manifestations had significantly higher levels of CIC when compared to other groups lacking these clinical features, whereas group 8 had a significantly lower level (P < 0.05) when compared to all other groups. Our results show that CIC may be involved in the pathogenesis of BD, especially in those clinical forms of the disease with erythema nodosum, neurologic manifestations, and ocular manifestations. Patients at the mild end of the BD spectrum do not show significant changes in CIC levels compared to healthy control subjects. We can, therefore, suggest that in BD CIC may be implicated more in the pathogenesis of some features than of others.

Utility of plasmatic levels of alpha-1-antiprotease (A1AP) as a cancer marker

The objective of this study was to evaluate the diagnostic utility as a cancer marker of plasmatic levels of A1AP. This case-control study included 135 cancer patients from different sites, confirmed histologically, and 95 controls (57 normal individuals plus 38 chronically ill patients with non-tumoral diseases). Determination of A1AP was done by a nephelometric procedure using a laser nephelometer as the measuring instrument. There were no sex or age related variations in plasmatic A1AP. Mean values of A1AP in 57 normal controls was 2.87 g/l (95% C.I., 2.58–3.15); in 95 non-tumoral individuals, including 38 chronic non-malignant diseases plus 57 normal controls, 3.09 g/l (2.46–3.72) and in malignant tumors, 4.12 g/l (3.80–4.45). There was a statistically significant difference between chronic diseases and normal controls ( P < 0.05) and also between cancer patients and non-tumoral individuals, normal control and chronic non-tumoral diseases ( P < 0.001). The means of plasmatic A1AP by tumoral site are increasing in this order: breast, gastrointestinal, head and neck, and lung. The means by clinical stage are increasing in this order: complete remission, local disease, local-regional disease and metastatic disease. The calculated cutoff value, excluding complete remission cases, is 3.37 g/l, with sensitivity 67.7% and specificity 67.7%. We conclude that there is an increase of plasmatic A1AP in cases of clinically active cancer compared with normal controls and normal range values in clinical complete remission. It can be an acceptable cancer marker that discriminates cancer from chronic non-tumoral diseases and complete clinical remission from relapses.

Determination of radiative properties of pulverized coal particles from experiments

A detailed experimental-theoretical procedure is introduced to determine the effective radiative properties of pulverized coal particles. A CO 2 laser nephelometer system was used to measure the scattered intensity distributions around a downflow of pulverized coal particles. A semi-analytical inverse radiation analysis was used to determine the ‘effective’ scattering phase function of particles without altering their morphology. The results showed that the phase function of coal particles was highly forward-scattering and less sensitive to size variations then predicted from the Lorenz-Mie theory for homogeneous spheres. They displayed more side scattering than predicted for spheres of the same size range, indicating irregular shapes and fragmentation of particles. An effective complex index of refraction m λ = 1.8 − 0.2 i is suggested for determination of coal radiative properties from the Lorenz-Mie theory using an ‘equivalent sphere’ model.

Scattering Tomography and Its Application to Sooting Diffusion Flames

A new analytical tomographic reconstruction technique was developed for the determination of the extinction and scattering coefficient distributions in axisymmetric media. This method, called “scattering tomography,” was tested for several particle concentration profiles corresponding to those for diffusion flames. After that, a series of experiments were performed on sooting acetylene flames using an argon-ion laser nephelometer. The experimental results were reduced using both the transmission and scattering tomography techniques to obtain the extinction coefficient profiles. It was shown that in the center of the flame, the results from these two approaches were in good agreement. Scattering tomography can be used to determine both the absorption and scattering coefficient distributions in the medium. In addition to that, it is preferable over the transmission tomography if the medium is optically very thin and particles are predominantly scattering.

Laser nephelometric evaluation of albumin, IgG and α2-macroglobulin: applications to the study of alterations of the blood-brain barrier

Cerebrospinal fluid and serum levels of albumin, immunoglobulin G and α 2-macroglobulin were determined by laser nephelometer in various pathological conditions: Guillain-Barré syndrome amyotrophic lateral sclerosis, lumbar disc herniation. These proteins are different due to their molecular weight, spacial conformation, CSF and serum concentrations and their CSF/serum quotient reflects the status of the blood-brain barrier. In the subjects group comparisons, albumin quotient and IgG quotient show a significant differentiations. The linear regression of albumin quotient compared to α 2-macroglobulin quotient behaves differently in the individual groups. The protein CSF/serum quotients are helpful in distinguishing the causes of alterations in the blood-brain barrier.

Forward and inverse analysis of single and multiple scattering of collimated radiation in an axisymmetric system

In this work, scattering of a collimated light source incident on a single/multiple scattering axisymmetric medium is studied and the extent to which analysis can be used to recover the effective radiative properties of the medium is determined. For this purpose, a He-Ne laser nephelometer is designed and the angular scattered intensity distributions measured in the single and multiple scattering regimes for mono- and polydispersed suspensions of particles. Analytical expressions are derived for the angular intensity distribution, accounting for up to two successive scatters. The experiments show very good agreement with the theoretical calculations. Also, an inverse analysis is presented to determine the phase function coefficients of particles in situ using the experimental results. The first two coefficients of the Legendre expansion of the phase function are recovered for both ymono- and polydispersions within 10% of the actual value for experiments conducted at low optical thicknesses ( τ < 0.5).

Inadequacy of Urinary Urea for the Estimation of Nitrogen Balance during Total Parenteral Nutrition

Measurement of urinary urea has been proposed as a convenient means to estimate urine nitrogen excretion, as the basis for prescription of amino acid nitrogen in parenteral feeds.l-? The validity of this procedure was investigated. Seven in-patients each with moderate to severe protein-calorie malnutrition (~80% ideal body weight and/or 0·3 giL protein. Plasma urea and C-reactive protein (CRP) were measured at 1-2 day intervals by the ophthaldehyde reaction, on a Parallel analyser (American Monitor, Burgess Hill, UK), and by end point immunonephelometry using a Hyland Laser Nephelometer PDQ (Travenol Laboratories, Norfolk, UK), respectively. The betweenbatch CV was < 5% in each case. If a rise in plasma urea occurred during the period of urine collection, the retained nitrogen was calculated and added to the estimates of total and urea nitrogen excretion.' The 24-hour urinary total and urea nitrogen excretions are shown in Table 1. They are closely correlated (Kendall's rank correlation coefficient = 0·80, P < 0,0001) and the mean fractional nitrogen excretion as urea is 0·79 (n = 49). The

Development of a multifunctional laser nephelometer using backward light scattering detection for clinical diagnosis of blood coagulation and fibrinolysis

A multi-functional laser nephelometer which detects backward light scattering has been developed for the clinical diagnosis of blood coagulation and fibrinolysis. This instrument measures the turbidity change at 790 nm in a blood coagulation reaction, an antigen-antibody reaction, or a latex agglutination reaction. In a blood coagulation reaction, the time required to detect the maximum rate of the turbidity change is measured as the coagulation time, from which the biological activity of the blood coagulation is automatically determined. Both in an antigen-antibody reaction and in a latex agglutination reaction, the maximum rate of the turbidity change is measured, from which the immunological activity of the target antigen is again automatically determined. The detection of backward light scattering, the optimization of electronic detection sensitivity, and the software switch of the differentiation parameters depending on the reaction rate of a respective item, make it possible to measure these three kinds of reactions with a common instrument. This method also reduces the measuring time of the immunological reaction compared with that of conventional endpoint methods. The coefficients of variation of the activity determined over each tested item are 0.583 to 5.03%. The correlation coefficients of the determined activity with conventional methods are as good as 0.968 to 1.000.

WC-14 Serum total cholesterol, apolipoprotein B, and apolipoprotein A I, following myocardial infarction

Cost of measuring serum specific proteins on the Hyland Laser Nephelometer (PDQ) is reduced from $1.60 (U.S.) per test to an average of 35 cents (range: 18–76) per patient result by preparing dilutions in polyethylene glycol of antibodies that are available commercially (Dakopatts a/s, Denmark). An expensive, cumbersome dilutor-dispenser used in the prescribed method is replaced by simple pipetting procedure. Antibodies employed were verified to be monospecific immunoglobulins raised each against one 11 human specific proteins studied, namely albumin, orosomucoid, alpha-1-antitrypsin, alpha-2-macroglobulin, haptoglobin, transferrin, beta-1-C-globulin (C3), beta-1-A-globulin (C4), and immunoglobulins IgG, IgA and IgM. Development of relative light scatter, measured nephelometrically, was shown to be stabilized within 40 minutes of adding sample to antibody. Linearity of graphs for six calibrating references in each method, relating concentration of standard to nephelometric relative light scatter, was excellent. Furthermore, very reproducible results were obtained from day-to-day (CV of 2 – 10%) for standard concentrations within ranges usually encountered clinically. Precision for Hyland Immunochemistry Control, measured against Hyland calibrating references, was acceptable (average CV: 7.6%; range: 5 – 11%). Due to lack of uniformity found previously in expressing concentration in different batches of Hyland Calibrators and Accuracy Controls, correlation of results obtained with Hyland antibodies versus those obtained with Dako antibodies was not carried out. Intermanufacturer comparison of results of the 11 proteins in commercial immunochemical quality control standards from Hyland and two other sources (Atlantic Antibodies, Behring Diagnostics) was disappointing. However, precision in measuring the same 11 specific proteins in controls of three commercial sources (Hyland, Atlantic, Behring) studied with Dako antibodies and Hyland calibration (average CV of 7.6, 10.5 and 11.1% respectively) was similar to that previously reported using Hyland antibodies and Hyland calibration (corresponding average CV of 7.6, 10.7 and 12.5% respectively). Dako antibodies were found to be well suited for use on the Hyland Laser Nephelometer. Need for proper standardization of calibration between various manufacturers is again emphasized.

Determination of five protein analytes using the beckman array™ and the behring nephelometer system

AbstractThe Beckman Array and the Behring Nephelometer offer the clinical laboratory completely automated discrete protein analysis. To select one of these systems, we compared five protein analytes: IgG, IgA, IgM, transferrin, and prealbumin. In addition to automation, we wanted to achieve better precision than our present method and have available a wider range of test selection. The Beckman Array gave 2‐week stability of calibration, analyzed lipemic samples without significant problems, and had direct manufacturer's service available. The Behring Nephelo meter offered a choice of single or multipoint calibration, retrieval of raw data, ease of operation, more flexibility in test parameters, and choice of calibrator. Interference from lipemia frequently caused variable results requiring pretreatment of the sample. Both instruments demonstrated excellent precision, linearity, and correlated adequately with the Hyland Laser Nephelometer PDQ. The Array demonstrated slightly better slope values than those of the Behring Nephelometer with the exception of prealbumin analysis.

The Immunochemical Relationships of Prolamins of Temperate Meadow Grasses and Cereals

Burgess, S. R., Festenstein, G. N., Hay, F. C. and Shewry, P. R. 1987. The immunochemical relationships of prolamins of temperate meadow grasses and cereals.—J. exp. Bot. 38: 247-253. The immunochemical relationships between the aqueous alcohol-soluble prolamin storage proteins of temperate cereals (wheat, barley, rye and oats) and five species of Festucoid meadow grasses (.Lolium perenne, Festuca rubra, F. arundinacea, Dactylis glomerata and Phleum pratense) were studied by 'Western Blot' analyses using antisera raised against C hordein of barley, y-gliadin of wheat and avenins of oats. In addition, the reaction between the C hordein antiserum and the grass prolamins was studied using a quantitative laser nephelometer assay. The results confirmed the previously reported structural relationship between the prolamins of Festuca and Lolium and members of the Triticeae (barley, wheat, rye). They also showed a strong antigenic relationship between the prolamins of Dactylis and Phleum and avenins of oats, and this is consistent with their molecular weights and amino acid compositions. The results indicate that similar immunochemical studies may be of value in clarifying the taxonomic relationships of Festucoid meadow grasses.

C-reactive protein levels predict postoperative septic complications.

We studied 108 patients undergoing clean-contaminated and dirty surgical procedures to determine whether daily C-reactive protein (CRP) measurements for 14 days postoperatively could predict the occurrence of septic complications prior to clinical diagnosis. Diagnostic criteria for septic complications and positive CRP response were defined in advance of the study. The CRP assays were carried out using an automated laser nephelometer system after the patient's discharge from the hospital. Forty-six septic complications were diagnosed in 40 patients. These complications consisted of wound infection (23), urinary tract infection (11), pneumonia (six), upper respiratory tract infection (three), intra-abdominal abscess (one), and other (two). The CRP testing was found to have a positive predictive value of 69% and a negative predictive value of 78%. We conclude that serial CRP measurements may be a valuable adjunct to surgical care in patients at high risk of postoperative septic complications.

Assay of immune complexes in infantile hydrocephalus among Nigerians

The immune complexes in infantile hydrocephalic CSF in Nigerian children using a laser nephelometer were quantified. The values obtained were relatively low when compared with the serum levels. There was no evidence of selective admixture or of a breakdown of blood-brain-barrier (BBB). The low levels of immune complexes, when associated with implantation of shunt device for treatment of the hydrocephalus, may be a predisposing factor that can lead to overwhelming infection among this group of patients in a developing country like Nigeria. Between the hydrocephalic fluid and lumbar CSF, an IgG gradient was found.

Detection of circulating immune complexes in patients with atopic dermatitis and psoriasis

Sera from 32 patients with atopic dermatitis and 22 patients with psoriasis were examined for the presence of circulating immune complexes (CIC) in comparison to 51 healthy controls using a PEG-precipitation laser nephelometer technique. Different patterns of the precipitated proteins were found in both diseases. In atopic dermatitis C3 and IgG were significantly elevated in CIC. Furthermore, significantly increased amounts of IgE were found in the precipitates. Groups with high and low serum IgE levels showed no significant differences in the quantity of precipitated proteins. Skin involvement did not correlate with CIC. In psoriasis patients, a different pattern with significantly increased IgA, IgG, IgM and C3 was found in the precipitates. IgE was also significantly increased in comparison to the controls. No difference was found between patients with psoriasis vulgaris and psoriasis guttata. CIC in psoriasis and in atopic dermatitis thus showed a characteristic composition. However, a detection of CIC was not directly related to the cutaneous manifestation of the disease.