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Biomedical subjects

L L Hause

Publications and source records attributed to L L Hause.

At least 19 recordsLinked to original sources
PubMed1991

Rapid determination of the rate constant of agonist-induced association of single platelets.

We have developed a rapid and convenient method for determining the rate constant of association of single platelets. Using the concentration of single platelets prior to activation and that 0.25 min (15 s) after activation, this rate constant can be determined accurately without concern for reversibility of the aggregation process or need for statistical analysis. A linear relationship between initial platelet concentration and the rate constant of association is defined. The clinical utility of this association parameter is discussed.

Adenosine Diphosphate↗
PubMed1990

Image analysis confirmation of DNA aneuploidy in flow cytometric DNA distributions having a wide coefficient of variation of the G0/G1 peak.

With nuclei extracted from paraffin-embedded tissues, resolution of normal diploid DNA and abnormal near-diploid/aneuploid populations by flow cytometry (FCM) is especially difficult. These samples, compared with fresh tissue, tend to show a broader DNA distribution, appearing as a wide (high) coefficient of variation (CV) of the G0/G1 peak. To address the question of whether there may be aneuploid populations hidden in wide CV diploid G0/G1 peaks, the authors measured DNA content in nuclei extracted from paraffin-embedded tumor tissue by morphometric image analysis (IA) in addition to FCM. Of 29 samples showing little evidence of DNA aneuploidy by FCM, in 20 of 20 with G0/G1 CVs greater than or equal to 5.50% there was an aneuploid population when analysis was performed by IA. Of the remaining nine samples with CVs less than or equal to 4.41%, all were diploid in the G0/G1 region by both FCM and IA. The presence of aneuploid populations in FCM distributions with wide CV G0/G1 peaks can be confirmed by IA.

Aneuploidy↗
PubMed1989

A compartmental model of platelet aggregation in vitro: the kinetics of single platelets.

A compartmental model of platelet aggregation which accurately describes both reversible and irreversible aggregation in vitro is presented. This model is substantiated by correlative analyses of agonist-induced aggregation as monitored by both routine aggregometry and resistive counting of single platelets. Previously unresolved differences in the reported reaction order of the aggregation process are explained. The model suggests that aggregation includes, in addition to the association and dissociation of platelets, the stabilization of aggregates. We find reversible aggregation requires that single platelets associate more rapidly than aggregates stabilize. For irreversible aggregation, our results suggest the presence of subpopulations of single platelets which associate at different rates. As an unexpected consequence of this study, quantitative relationships between photometric and resistive methods of monitoring platelet aggregation are elucidated.

Adenosine Diphosphate↗
PubMed1989

Differences between values for plasma and serum in tests performed in the Ektachem 700 XR Analyzer, and evaluation of "plasma separator tubes (PST)".

We measured 25 analytes in plasma and serum from the same blood specimen, using the Kodak Ektachem 700 XR Analyzer. For 22 of the analytes, values for plasma were practically the same as those for serum; for the other three, differences between concentrations in plasma and serum were significant, both statistically and medically. Values for the same analytes in plasma from regular heparinized tubes were essentially indistinguishable from those for plasma obtained by use of Plasma Separator Tubes (PST).

Adult↗
PubMed1987

The determination of the eosinophil count: comparison of two techniques.

The total eosinophil count obtained by use of the standard hemacytometer is considered by several investigators to be the most reliable method for the determination of the circulating eosinophil levels in the blood because it is believed to be less subject to error than the calculated eosinophil count obtained with Wright stained blood smears from the differential count. We compared the two techniques in outpatients as well as inpatients with and without allergies (total of 514 patients). Our results demonstrate that the eosinophil count by the two methods are similar.

Eosinophils↗
PubMed1986

A platelet aggregating factor in thrombotic thrombocytopenic purpura: initial activity, fluctuations, and removal by plasma exchange.

A factor capable of aggregating normal platelets was found in the plasma of six consecutive patients with thrombotic thrombocytopenic purpura (TTP). The activity of the aggregating factor in whole plasma, the cold protein fraction from plasma and the residual supernatant was monitored during each patient's course of therapeutic plasma exchange. Although two patients demonstrated the highest level of aggregating activity at the time of diagnosis, the level fluctuated in five of six patients. Increasing levels of activity were usually accompanied by signs of clinical deterioration. Activity repeatedly within the normal range was not seen until remission of the syndrome. Neutralization of the aggregating activity in vivo through removal of patient plasma and replacement with fresh frozen plasma (plasma exchange) was accomplished less readily and less predictably than by mixing patient plasma and normal plasma in vitro. Use of the aggregating factor level in evaluating the need of plasma exchange is discussed.

Adult↗
PubMed1985

Hierarchical information system for the cost analysis of clinical laboratory tests.

A microcomputer-based information system that integrates the concepts of text processing, data base processing, and data base analysis has been designed for cost evaluation in our laboratories. This forms a flexible package that is directed by the needs of the user. The package, which has been used to calculate various cost parameters and productivity on the basis of comprehensive data and user-defined rules, serves as a tool for good financial management at various organizational levels in the clinical laboratory.

Clinical Laboratory Techniques↗
PubMed1985

Candidate reference method for determination of total bilirubin in serum: development and validation.

This candidate Reference Method for measuring total bilirubin in serum is based on the Jendrassik-Gróf principle (Clin Chem 29: 297-301, 1983). Standard Reference Material no. 916 bilirubin (National Bureau of Standards) is used as the standard. Bilirubin standard solutions may be prepared either in human serum or in 40 g/L albumin solution (human or bovine), because we found the molar absorptivity of the azopigment at 598 nm to be identical in these media. The absorptivities of the unconjugated and conjugated azopigments appear to be identical, but the conjugated azopigment is completely hydrolyzed in the final reaction mixture. Bilirubin added to serum from adults or neonates was quantitatively accounted for. Interference by hemoglobin (up to 2 g/L), ascorbic acid (up to 20 mg/L), or zinc (at physiological concentrations) is negligible. Of the therapeutic drugs we tested, only L-dopa and alpha-methyldopa interfere. We established normal adult reference values for total bilirubin and examined the intraindividual variation in 19 subjects.

Adult↗
PubMed1984

Cardiopulmonary responses of asthmatic children to strenuous exercise. Effect of theophylline.

The purpose of the study were to investigate the cardiopulmonary adaptations of asthmatic children to physical exercise and to evaluate the effects of theophylline. Two groups of children were evaluated. Eight asthmatic children participated in two exercise sessions. Half of the patients received theophylline in predetermined doses during the first session and half prior to the second session. Seventeen normal children matched for age, height, and weight served as controls. Various cardiorespiratory parameters were measured every 2 minutes during exercise and prior to termination of maximal physical effort. The results indicate that children with chronic asthma reach the range of predicted maximal aerobic capacity for their age. Theophylline increases the endurance of asthmatic children to maximal physical efforts without improving the cardiorespiratory parameters that were measured. The use of theophylline in therapeutic doses appears safe under conditions of vigorous exercise.

Adolescent↗
PubMed1982

The effect of bovine lung heparin on normal human platelets as measured by electronic particle size analysis.

The response of normal human platelets to treatment with bovine lung heparin was evaluated using electronic particle size analysis and aggregometry. Samples for electronic particle size analysis were obtained both before and after the addition of heparin to platelet-rich plasma (PRP). The number of single platelets decreased significantly after the addition of heparin to PRP obtained from 22 individuals. This decrease averaged 18% in 19 samples which did not show a significant increase in transmittance and was at least 70% in 3 samples which showed a significant increase in transmittance. The size distribution of single platelets was not significantly altered. In addition, electron microscopic examination revealed that platelets treated with heparin are activated.

Adenosine Diphosphate↗
PubMed1982

The measurement of lymphocyte size and thymidine uptake in comparative response to mitogen stimulation in vitro.

Measurements of thymidine uptake and cell size with the Coulter ZBI Counter and C-1000 channelyzer were found to be comparable for mitogen-stimulated lymphocytes. These two technics show a discrete relation with correlated regions of high and low response. Electronic sizing was correlated linearly to microscopic sizing of lymphoblasts. The reproducibility of radiolabeled and electronic sizing measurements were similar and significantly better than that of manual microscopic sizing. The distribution of lymphocyte sizes after two or three days in culture with mitogen was found to be bimodal. This facilitated the direct detection of stimulation responses with the ZBI counter.

Cells, Cultured↗
PubMed1981

Collagen-induced platelet aggregation as studies by electronic particle size analysis.

The collagen-induced response of free platelets during aggregation was measured with an electronic particle size analyzer. Aggregation was induced in platelet-rich plasma by 0.05 mg/mL collagen. The reaction was followed turbidimetrically and samples for electronic particle size analysis were obtained during aggregation. Free platelet number decreased rapidly after the addition of collagen. This decrease preceded detectable changes in transmittance and a significant reduction in free platelet number was measured during the classical lag phase. In addition, the size distribution of free platelets at various times after the addition of collagen was not significantly altered indicating that large platelets are not preferentially involved in collagen-induced aggregation.

Collagen↗
PubMed1981

A candidate reference method for determination of total protein in serum. II. Test for transferability.

The transferability of the candidate Reference Method for total serum protein was tested in eight laboratories in the United States and Europe. National Bureau of Standards SRM 927 (bovine serum albumin) was used in each analytical run as the calibration standard. The mean absorptivity value obtained for this material was 0.2983 L g-1 cm-1. Four serum pools prepared at the Centers for Disease Control were analyzed on each of 15 days. Within-run variation of the protein values (expressed as CV) in the eight laboratories ranged from 0.1 to 2.5% and day-to-day (total) variation in six of the laboratories ranged from 0.4 to 1%.

Biuret Reaction↗