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Biomedical subjects

L Smith

Publications and source records attributed to L Smith.

At least 631 records · Page 35Linked to original sources
PubMed1979

Visual and automated differential leukocyte counts. A comparison study of three instruments.

The authors compared referee (senior author) microscopic counts, microscopic counts by several technologists, and counts obtained with two pattern-recognition leukocyte classifiers, (1) Larc and (2) Hematrak, and a cytochemical automated method for leukocyte counting, (3) Hermalog D, using samples from (1) a random patient population, (2) a selected abnormal patient population, and (3) healthy individuals. All instruments showed good accuracy and flagged abnormal results for review. Variability in pattern-recognition counts was found to be due mainly to the distribution of the cells on prepared blood smears. The Larc classifier was found to be very sensitive to minor alterations in the cytoplasm or nucleus, and rejected a number of slides. The Hemalog D showed the greatest precision. The method of preparation of slides would be a major decision factor in selecting one pattern-recognition instrument over another.

Adult↗
PubMed1979

Efficient interaction for automated chromosome analysis using asynchronous parallel processes.

It is likely that any practical automated chromosome analysis system will be interactive. To prevent long pauses in the stream of operator interactions, it is necessary, if using standard computer hardware, to configure for asynchronous and parallel operation. A system is presented which uses several computer processors, which can support one or more operators, and which divides processing into interactive and noninteractive sections, smoothes the rate of presentation of interactions, and keeps both the operator and the computer fully employed.

Chromosomes, Human↗
PubMed1979

Serological markers for hepatitis types A and B among U.S. Arym soldiers, Germany.

Viral hepatitis rates among U.S. Army soldiers in Europe have been found to be two to three times higher than corresponding rates for soldiers stationed in the U.S. Sera from 89 per cent of a representative Army unit with 865 members and a known hepatitis problem were tested for HBsAg, anti-HBs, anti-HBc, and anti-HA. The prevalence of HB markers was 20 per cent, and hepatitis A antibody was present in 25 per cent. A six-month follow-up, conducted on 260 individuals initially negative for all four tests, revealed that 11 of these were now HB seropositive, whereas none had seroconverted to anti-HA positive. The HB virus was the principal agent responsible for hepatitis in the unit surveyed.

Adult↗
PubMed1979

Angiotensin-converting enzyme in sarcoidosis: a British study.

Serum angiotensin-converting enzyme (ACE) activity was measured in 18 healthy controls, 26 patients with active sarcoidosis, 13 patients with inactive sarcoidosis and seven patients with extensive tuberculosis. The serum ACE activity showed no significant difference between male and female in the control or sarcoidosis groups. There was no correlation between ACE activity and age except in the female active-sarcoid group. ACE activity in the active-sarcoid group was significantly higher than in the control, inactive-sarcoid and tuberculosis groups. The ACE activities at Stages I, II and III of the disease were not significantly different.

Adult↗
PubMed1979

Automated measurement of total cholesterol and triglycerides, in "tandem," on the discrete sample analyzer, Gilford System 3500.

We have developed an automated procedure on a discrete sample analyzer, Gilford System 3500, which alternately measures both total serum cholesterol and triglyceride concentrations as a "tandem" procedure. We used Dow Diagnostic's fully enzymatic, colorimetric reagents and aqueous standards to calculate unknowns ratiometrically. Cholesterol and then triglyceride reagent are dispensed into alternate cups; the produced color at 500 nm is measured after an ambient temperature incubation of 20 min. Reagent and sample carryover is less than 1.6%. Correlation coefficients of 0.997 for comparison for both automated tests with the manual methods at 30 degrees C and a typical CV of less than 2.0% show this "tandem" procedure to be reliable and accurate.

Autoanalysis↗
PubMed1978

Limit-setting.

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Humans↗
PubMed1978

Possible detection of HLA-DR alloantigenic specificities in man with unabsorbed rabbit antisera.

Thirty-six rabbits were immunized with precipitin lines formed between detergent solubilized membrane fractions from HLA-D-homozygous cells and a rabbit antiserum to human B cells (anti-p 23/30). Thirty-one of the rabbits produced B-cell specific cytotoxic antibodies and twelve of the antibodies were also precipitating in gel diffusion. In cytotoxicity tests six of the antisera showed clear preferential reactivity with the immunizing HLA-D (DR) antigen. Thus immunization of rabbits might prove valuable for the production of HLA-DR typing reagents.

Animals↗
PubMed1978

Multi-laboratory comparison of three heparin-Mn2+ precipitation procedures for estimating cholesterol in high-density lipoprotein.

Plasma high-density lipoprotein is commonly estimated by measuring the cholesterol remaining in plasma supernatant solutions after other lipoproteins, which contain apolipoprotein B, are precipitated with heparin and Mn2+. The method (method I) now in use by the Lipid Research Clinics, in which Mn2+ is at 46 mmol/liter final concentration, is reasonably accurate, but precipitation and sedimentation of lipoproteins other than high-density lipoproteins is often incomplete. We evaluated two modifications of method I. In method II, the Mn2+ concentration was doubled; the second modification (method III) included the increased Mn2+ concentration in a combined heparin Mn2+ reagent, decreased sample volume (2 ml), and a shorter incubation time (10 min at room temperature). The percentages of samples with turbid supernates (i.e., incomplete sedimentation) by methods I, II, and III were 9, 3, and 2%, respectively. Among non-turbid supernates, the percentages of samples containing measurable apolipoprotein B (incomplete precipitation) were 79, 19, and 16%, respectively. We conclude that method III is the most convenient and accurate of the three procedures.

Chemical Precipitation↗
PubMed1978

Automated procedure for kinetic measurement of total triglycerides (as glycerol) in serum with the Gilford System 3500.

An automated procedure is used on the Gilford 3500 Computer-Directed Analyzer to measure serum triglycerides indirectly by using aqueous glycerol standards. Most enzymatic methods require long hydrolysis or awkward saponification. The method of Bucolo and David [clin. Chem. 19, 476 (1973)], in which lipase and glycerol kinase are used, is modified. The kinetic procedure described eliminates the need for a serum blank. It uses "Eskalab" bulk reagents and reduces both time and cost per test by measuring the decreasing NADH concentration from the glycerol kinase reaction at 340 nm after enzymatic hydrolysis at room temperature. The change in absorbance of the standard during a 14-s measuring time is used in the ratiometric calculation of the unknowns. The use of a stable aqueous standard that can be reliably and accurately prepared makes this method ideal for the traceability desired by many organizations. Reagent blank drift did not affect the results. A correlation coefficient of 0.991 for comparison with the manual endpoint method and a typical CV of 2.25% show this method to be accurate and reliable.

Autoanalysis↗
PubMed1978

Secular variation in frequency of premature ventricular contractions in untreated individuals.

Six-hour electrocardiographic monitorings were initially recorded from 40 ambulatory adult subjects (39 male, one female) on successive days. Thirty-eight of the subjects were monitored 6 weeks to 18 months later. Studies of paired time periods, Poisson modeling, and other statistical examinations were performed. Despite an underlying consistency in the data, there was considerable variation in PVC frequency from hour to hour, day to day, and over longer periods of time.

Adult↗