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At least 703 records · Page 39Linked to original sources
PubMed2003

Development of thermochromic strips as a water pasteurization indicator.

Boiling of water, for purification, commonly practiced in the world, has many problems associated with it like danger of scalding, scaling in the vessels, removal of useful minerals and blandness of taste etc. Water can be made safe for drinking simply by heating at 65 degrees C for 6 minutes. A colour indicating strip was developed which changes colour from red to purple at 67 degrees C. Use of this strip can help in pasteurizing water without the above problems and with considerable energy saving.

Hot Temperature↗
PubMed1994

A marvel of colors and ingredients. The story of urine test strip.

The history of the urinary test papers does not being in the post-war period. As early as the 1880's some practitioners and pharmacists tried to replace the complicated wet-chemical procedures and apparatus by "dry chemistry." The first popular test paper for sugar and albumin originated in England in 1883. Dry reagents for proving hematuria have been available since the beginning of this century. Until the 1930s a wide palette of commercial urine tests with "modern" brand names was established. A methodological breakthrough was created by the spot test chemistry inaugurated by the Austrian, Fritz Feigl, about 1920. Using the capillary properties of filter paper in enhancing color reactions he founded a new area of analytical chemistry. Many of the pioneers were recruited from Jewish scientists. In this lecture is proposed that their emigration and banishment as well as the Second World War have stopped the development of urinary diagnostics on the European continent. In the post-war period the American industry succeeded to the leading position in the researching and marketing of test papers. In 1956, the triumphal progress of the "stick tests" began with the "Clinistix" (Ames Company, today Bayer Diagnostic).

Color↗
PubMed2004

Spectrophotometric determination of leukocytes in urine.

A spectrophotometric method based on myeloperoxidase activity for the determination of leukocytes in urine is described. Red cells that may be found in urine samples were lysed by an ammonium chloride method. Leukocytes were then sedimented by centrifugation and lysed using Triton X-100 (Sigma Chemicals Co., St. Louis, MO). Myeloperoxidase-catalyzed oxidation of o-dianisidine was carried out at 37 degrees C, pH 7. The reaction was stopped with the addition of 2 M H2SO4, and a stable form of oxidized o-dianisidine in acidic solution was obtained. Solid particles that may be found in urine samples were removed by centrifugation to avoid turbidity, and absorbance values of the supernatants were recorded at 400 nm. An Average number of leukocytes were noted per number of fields by microscopic examination and were related with the absorbance values of the supernatants at 400 nm. Pearson correlation (r) between our presented spectrophotometric analysis results and visual microscopic analysis was 0.877. Roche Combur 10-test M strips (Roche, Mannheim, Germany) and Multistix 10 SG Bayer test strips (Bayer Diagnostics, UK) were 0.645 and 0.648, respectively (P < 0.0001).

Dianisidine↗
PubMed1986

Glucose analysis: indications for ordering and alternatives to the laboratory.

Cost considerations mandate that the emergency physician consider the use of test strips for glucose analysis. Presented are medical criteria for glucose analysis, a description of available test strips and reflectance meters, and data from studies which compare performance and cost of the strips with laboratory methods. Emergency physicians should study the test strips and their indications more comprehensively. In general, glucose test strips provide a clinically acceptable means for blood glucose determinations.

Blood Glucose↗
PubMed1986

Ascorbate interference in the estimation of urinary glucose by test strips.

Currently used test strip methods for the detection of glucose in urine are influenced by ascorbate and may thus give false negative results, e.g. in screening for diabetes. Six different test strips for urine glucose were evaluated for interference by ascorbate in vitro. Interference by ascorbate varied markedly, being highest at low glucose concentrations. Interference coefficients for the individual tests were calculated to serve as an approximate index of interference by ascorbate. A new test (BM 33.071, Boehringer Mannheim GmbH, currently used in Combur-9-Test/Chemstrip-9 and other multiple test strips of Boehringer Mannheim) was clearly much less influenced as no urine containing 5.5 mmol/l glucose was read as negative even at very high ascorbate concentration. Readability of test strips differed due to patchy colour reactions. Precision was good within-test strip and within-urine but markedly less between urines.

Ascorbic Acid↗
PubMedDate not supplied

Less expensive, reliable blood glucose self-monitoring.

We examined the reliability of split test strips for blood glucose self-monitoring. One hundred visual readings were performed with each of the following test strips: original Haemoglukotest 20-800 (HGT 1/1; Boehringer-Mannheim, Mannheim, FRG) and Haemoglukotest 20-800 halved either by a splitting device (HGT 1/2 SP) or by a pair of scissors (HGT 1/2 SC). Within the plasma glucose range of 20-360 mg/dl, there was a close correlation between the results of all three test-strip readings and the values obtained by the reference method (Beckman glucose analyzer): HGT 1/1, r = .950; HGT 1/2 SP, r = .966; and HGT 1/2 SC, r = .966. Absolute deviations from the reference values were 17 +/- 2, 17 +/- 1, and 17 +/- 1 mg/dl (mean +/- SE). Analysis of variance did not reveal any significant differences between the values of each of the three procedures compared with the reference method (P = .98). These results indicate that visual reading of split test strips is as reliable as the reading of original test strips. A special splitting device is not necessary. Diabetic patients should be advised to use split test strips for blood glucose self-monitoring to reduce costs.

Analysis of Variance↗
PubMed1981

Calibration of a strip test for urinary urobilinogen using a mercuric chloride assay with crystalline reference standards.

A strip test based on Ehrlich's reaction has improved specificity for urobilinogen in urine. Strip reactions are calibrated in mg/dl using a recently developed reference assay which is based on a mercuric chloride reaction and includes a crystalline reference standard. Strip reactions correlate well with the mercuric assay when the urine sample contains only urobilinogen. If a urine contains urobilin in addition to urobilinogen, the strip test gives slightly lower values than the reference assay. The strip test reacts only with urobilinogen but the reference assay measures urobilin as well as urobilinogen. Comparative data with both tests are included for normal and pathological urines. Reaction colors with the strip test have been characterized in L* a b* values, an international basis for color designation.

Calibration↗
PubMed1986

A comparison of three methods for determining the concentration of rat urine.

The concentrations of 78 rat urines were compared using osmometry, refractometry and test strips for specific gravity. Test strip specific gravity values are a guide to urine concentration; where small changes of urine concentration are expected, the test strips should not be a replacement for more accurate methods such as osmometry.

Animals↗
PubMed1993

Application of a leukocyte and nitrite urine test strip to the management of children with neurogenic bladder.

A urine leukocyte count of > or = 50/mm3 together with a bacterial count of > or = 10(5) colony-forming units (CFUs) per milliliter was used to define significant infection in 160 children with neurogenic bladder and evaluate the leukocyte and nitrite components of the Chemstrip 9 test. A Chemstrip 9 leukocyte reading of < or = 25 together with a negative nitrite reaction occurred in 99 children and had a sensitivity of 83.5% and a negative predictive value for infection of 97.0%. A Chemstrip 9 reading of > or = 500 leukocytes together with a positive nitrite reaction occurred in 18 children and had a sensitivity of 40% with a 100% positive predictive value for infection. Other combinations of Chemstrip 9 leukocyte and nitrite reactions were unhelpful or of uncertain value. Selection of up to three specimens from each patient increased the number of samples to 360 and provided general confirmation of the above conclusions. Nitrofurantoin may reduce the sensitivity of the nitrite strip reaction.

Child↗
PubMedDate not supplied

Use of continine immunoassay test strips for preclassifying urine samples from smokers and nonsmokers prior to analysis by LC-MS-MS.

Cotinine biomarker measurements involving both smokers and nonsmokers must accommodate a broad range of concentrations. Thus, we have routinely preclassified unknown samples as being either "high" or "low" by using an enzyme-linked immunoassay for cotinine prior to analysis by tandem mass spectrometry (MS). Although this method is effective, it is also time-consuming and complex; a simpler and faster approach would be useful. Consequently, a screening assay for urine cotinine using an immunochromatographic test strip (NicAlert) followed by a computerized analysis of the data was examined as a possible alternative. The results indicate that this approach can provide useful classification efficiency when using our target cutoff value of approximately 20 ng/mL. In the analysis of 50 urine samples from nonsmokers with varying degrees of exposure to environmental tobacco smoke, the classification sensitivity and specificity were 88% and 92%, respectively, for cotinine measured by the test strips relative to total cotinine concentrations measured by atmospheric-pressure ionization tandem MS. However, the relatively high cost of the strips may be a limiting factor.

Calibration↗
PubMed1990

Sample, count, identify, and store the mutans streptococci.

According to a new method for sampling mutans streptococci, "Strip mutans", a plastic strip is contaminated by human saliva and incubated in a selective broth. After growth the strip with adherent colonies may be dried and stored. We wanted to know for how long a time bacteria in the colonies were viable if the strips were stored under different conditions. The survival time is important if the bacteria need to be subjected to further analyses. The results showed that the viability of the bacteria after the incubation period was at least 1 yr when the strips were stored frozen or frozen in glycerine. Stored dried in room temperature the survival was about 8 wk. A second part of the study aimed at identifying the colonies on strips obtained from different countries. Dried strips were sent air mail to our laboratory for biochemical and immunological analyses and the results showed that serotype/biotype c/e/f of S. mutans were most frequent but d/g S. sobrinus was also present in the samples, which came from Brazil, Greece, and Sweden. Three colonies of 213 on these strips did not grow, possibly indicating non-mutans bacteria.

Adolescent↗
PubMedDate not supplied

Screening nitrate in forages with a test strip: collaborative study.

A collaborative study was conducted for screening nitrate in forages with a commercially available test strip. The method involves extracting a finely ground sample with deionized water. The test strip is dipped in the sample extract. The color of the reaction zone on the test strip changes from white to pink or purple depending on the nitrate concentration in sample extract. The nitrate present in the extract is determined by comparing the color of the test strip to the color scale on the test strip container. Six blind quintuplicates of forage samples were analyzed by 20 collaborators. Nitrate concentrations in forage samples tested ranged from < 1000 ppm nitrate to > 10,000 ppm nitrate on dry matter basis. Each collaborator was asked to assign each sample to one of the 4 following nitrate concentration ranges: (1) < 1000 ppm, (2) 1000 to 5000 ppm, (3) > 5000 ppm to 10,000 ppm, and (4) > 10,000 ppm. Nineteen of 20 collaborators reported results. Results from 2 laboratories were rejected as outliers by inspection and chi 2 test. Sensitivity rates (p+) ranged from 0.965 to 0.998, with standard errors of 0.006 to 0.16. Specificity rates (p-) ranged from 0.991 to 0.997 for the 4 ranges, with standard errors of 0.003 to 0.006. False-positive rates (pf+) ranged from 0.006 to 0.046, with standard errors of 0.006 to 0.025. False-negative rates (pf-) ranged from 0.003 to 0.007, with standard errors of 0.003 to 0.006. Screening nitrate in forages with a test strip has been adopted first action by AOAC INTERNATIONAL.

Animal Feed↗
PubMed1989

[Screening for bacteriuria in the laboratory: autotrak, test strips and microscopic examination compared with culture].

A prospective investigation was undertaken to compare quantitative culture of 739 samples of urine in a microbiological laboratory with the screening methods: phase contrast microscopy examination, test strip examinations for nitrite and leukocyte esterase (Multistix-2, Ames) and "Autotrak" (automatic quantitating of the bacterial content in fluids: BBT instruments). The three screening methods were, by and large, of equal value as regards true positive diagnostic frequency (0.48-0.55) and true negative diagnostic frequency (0.92). The methods were also equally rapid but microscopy examination was by far the cheapest (0.15 Danish crowns per test as compared with 1.75 for test strips and 3.10 for "Autotrak"). In addition, microscopic examination has the further advantage, although this of lesser value where cocci are concerned, of being capable of differentiating the morphology of the bacteria and their motility. It is noted that test strips have a false negative rate of approximately 13%.

Bacteriological Techniques↗
PubMed1991

Application of a sucrose indicator strip to evaluate salivary sucrose clearance.

This study examined salivary sucrose clearance times of 96 subjects using sucrose indicator strips. Subjects with high caries experience had a longer salivary sucrose clearance time than those with a low caries experience. The flow rate of unstimulated but not of stimulated saliva was significantly related to sucrose clearance. This finding is consistent with that of other studies on salivary clearance. The sucrose indicator strips are simple to use and sucrose clearance tests using these strips do involve instrumental analyses. It is concluded that the strips investigated are simple and effective and merit further investigation.

Adult↗
PubMed2002

The accuracy of self-reported smoking status assessed by cotinine test strips.

We evaluated a new cotinine test strip to assess smoking status. Urine cotinine was measured using cotinine test strips and also by gas chromatographic techniques (GC) (as the reference criterion). Smoking status was assessed with a self-administered questionnaire. The cotinine test strip identified smokers with a very high level of agreement (97.3% using 100 ng/ml and 97.1% using 250 ng/ml for the cutoff point) and non-smokers with a fair-to-moderate level of agreement (74.5% using 100 ng/ml and 86.4% using 250 ng/ml for the cutoff point). These data suggest that the cotinine test strip appears to provide a reasonably accurate measure of smoking status. Since this was the first study to evaluate the cotinine test strip using the test strip prototype, larger clinical trials are needed to evaluate the validity of the cotinine test strip compared to GC measurements to confirm smoking status.

Adult↗