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At least 145 records · Page 8Linked to original sources
PubMed1991

Verification of the disector method for counting neurons, with comments on the empirical method.

The empirical and disector methods are unbiased sampling methods for determining numbers of neurons. The present study verifies and thus calibrates these methods by determining true numbers of ganglion cells in serial reconstructions and then using each method to estimate the same populations. The empirical method gives accurate counts but is laborious (inefficient). Five separate disector analyses, distinguished by height (h), were done for each ganglion. The findings are: (1) that the estimates are consistently low when h is minimal (reference and look-up sections are adjacent), but (2) the estimates are accurate when h is greater (one to four sections intervene between reference and look-up sections). We ascribe the difficulties with the first disector to "lost" or "invisible" caps. We emphasize that we would not have known of the problem unless we verified our counts. If there is suspicion that difficulties with profile recognition might occur, we recommend that serial sections of an appropriately chosen sample of tissue be prepared and 500-1,000 neurons (or, more generally, particles) be reconstructed. Then the method of choice can be used on the issue of choice to make certain of the necessary accuracy before proceeding with the main study.

Animals↗
PubMed1992

Which method for quantifying "microalbuminuria" in diabetics? Comparison of several immunological methods (immunoturbidimetric assay, immunonephelometric assay, radioimmunoassay and two semiquantitative tests) for measurement of albumin in urine.

We have compared the chemical and clinical characteristics of an immunonephelometric assay (INA), two immunoturbidimetric assays (ITA) and two semi-quantitative methods with those of a solid-phase radioimmunoassay (RIA) for measurement of urinary albumin (UA) concentration in 136 diabetic patients. INA and RIA had similar accuracy, and provided comparable results. However, RIA has slightly greater sensitivity than INA, which is easier and faster. Good agreement was also found between RIA and the two ITA methods, although one of these overestimated RIA values in the low-medium range (5-30 mg/l) of urinary albumin. ITA seems suitable for initial screening of albuminuria in diabetic patients but more sensitive procedures (such as RIA and INA) seem preferable for measurement of UA concentrations in the normal range. The two semi-quantitative methods showed high sensitivity but poor specificity, because of the large number of false positive results. About 50% of diabetic patients "positive" by these methods did not have microalbuminuria. The utility of these methods is questionable, because many samples from diabetic patients need to be reassayed by a more specific and sensitive assay such as the RIA, INA or ITA methods.

Albuminuria↗
PubMed1984

Urinary excretion of histamine, methylhistamine (1-MeHi) and methylimidazoleacetic acid (MeImAA) in mastocytosis: comparison of new HPLC methods with other present methods.

New HPLC-methods for the determination of histamine, 1- MeHi and MeImAA in human urine were compared with methods presently at use in our laboratory, the enzymatic double-isotope assay for histamine, the DNFB-method for 1- MeHi and the semiquantitative estimation of MeImAA by thin layer chromatography (TLC). A fairly good agreement between the methods was obtained for the measurement of histamine and 1- MeHi , although there was a rather large random error probably due to poor precision of the present methods. The TLC-method for MeImAA used so far overestimated by about 20% the HPLC-values, probably due to inaccurate correction for recovery by the internal standard technique. There was found to be a strong correlation between the urinary excretion of 1- MeHi and MeImAA in mastocytosis patients and the molar ratio MeImAA /1- MeHi appeared significantly higher compared to normal controls and patients with chronic granulocytic leukemia indicating in general a more efficient histamine catabolism in mastocytosis.

Adult↗
PubMed1980

Determination of free and esterified cholesterol by a kinetic method. II. Evaluation of the enzymic method which uses 2,2-azino-di(3-ethyl-benzthiazoline-6-sulfonate) (ABTS) as chromogen.

A simple kinetic method for the determination of free and esterified serum cholesterol based on the oxidation of 2,2'-azino-di(3-ethyl-benzthiazoline-6-sulfonate) (ABTS) by use of choilesterol esterase, cholesterol oxidase and peroxidase has already been reported. Here the method is statistically examined. The method is very sensitive and precise (C.V. below 5%). The standard curve is linear up to 25.9 mmol/l. Comparison with results by Abell's method gave a linear regression of Yx = 0.2025 + 1.0043X with a correlation coefficient (r) of 0.983. Comparison with the enzymic methods of Roeschlau et al., Trinder, and Allain et al. gave Yx = 0.2037 + 0.9549X (r = 0.975), Yx = 0.4777 +0.8857X (r = 0.958) and Yx = 0.244 + 0.932X (r = 0.970), respectively. The effects of haemoglobin and bilirubin were studied and normal ranges for the method were determined on 150 healthy mature subjects of both sexes between 20 and 45 years of age. They are 3.375 to 6.948 mmol/l for total cholesterol, and 0.7196 to 2.089 mmol/l for free cholesterol.

Adult↗
PubMed1992

A non-organic and non-enzymatic extraction method gives higher yields of genomic DNA from whole-blood samples than do nine other methods tested.

We compared ten methods for extraction of DNA from whole blood. Nine methods require incubation with either enzymes or treatment of organic solvents or both. The 'Rapid Method' (RM) (Method 10) avoids the use of organic solvents (phenol/chloroform) and eliminates completely the use of proteinase K. Thus, the time and cost of DNA extraction are reduced significantly. This is accomplished by salting out and precipitation of the cellular proteins in saturated sodium chloride. This method takes less than an hour to completion, without compromising the yield or the quality of DNA. Using RM, we can make DNA from 0.1 ml of whole blood and as little as 0.5 ml of blood yields DNA sufficient to run a few Southern blots. The RM can also be applied to packed cells. The DNA is free of RNA, protein and degrading enzymes. The uncut DNA runs as a typical slow-migrating, high-molecular-weight and undegraded species in an agarose gel. The DNA is suitable for digestion by various restriction endonucleases. This procedure works equally well with fresh blood samples and with those that are stored at 4 degrees C and -70 degrees C. To our knowledge the RM reported here is the safest, fastest and most quantitative and economical method for preparation of DNA from whole blood and cells.

Chemistry Techniques, Analytical↗
PubMed1992

A method for computer simulation of ultrasound Doppler color flow images--I. Theory and numerical method.

Ultrasound imaging systems utilizing the pulsed Doppler principle are capable of providing images of blood flow in real time. We present a useful method for simulating flow images on a computer. Our method assumes that blood and surrounding tissue consist of many point-like scatters positioned randomly in three dimensions. The position-dependent acoustic response of each scatterer is calculated using the acoustic impulse response method. This method takes into account the spatial effects of the transducer geometry on both the amplitude and temporal response of point-scattering. Details of theory, assumptions made in the simulation, and numerical methods are described fully for a spherically focused transducer, as well as a discussion of signal processing for generation of the flow image. Motion of a single scatterer is investigated to test the performance of the simulation algorithm. This simulation method could potentially be beneficial for detailed study of current and future flow imaging systems.

Blood Flow Velocity↗
PubMed1991

The reliability and stability of a quantity-frequency method and a diary method of measuring alcohol consumption.

The study aimed to assess the test-retest reliability of two commonly used measures of alcohol consumption, the quantity-frequency (QF) method and the diary method, as well as the stability of scores on the two measures over time. Two methods of assessing reliability and stability were employed. The first was a traditional method based on calculation of correlation coefficients for agreement between scores on repeated measures over a short retest interval to yield test-retest reliability coefficients, and over a long retest interval to yield stability coefficients. The second method was that devised by Wiley and Wiley (1970) to differentiate the effects of reliability and stability on repeated measures over time. The two methods were applied to a sample of heavy drinkers and to a sample of light drinkers. The results indicated that both the QF and diary measures are reliable in measuring alcohol consumption of light drinkers. Both measures are less reliable for heavy drinkers. The results indicate, in addition, that drinking consumption levels of light drinkers demonstrate a high degree of stability. However, the consumption levels of heavy drinkers demonstrate less stability, especially over a long time period. Heavy drinkers significantly reduced reported levels of alcohol consumption on both measures after the first test, suggesting a regression to the mean effect or the possibility of unintended intervention effects due to repeated measurement of drinking behaviour.

Adult↗