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At least 73 records · Page 4Linked to original sources
PubMed1994

Blood conservation in the critically ill.

The insertion of arterial lines has become a routine procedure for the critically ill. Valuable patient data can be obtained from the arterial line, nursing and laboratory personnel time can be saved, and patient discomfort can be minimized. However, increased blood loss is incurred and may result in nosocomial anemia. This blood loss can be sharply reduced by heightened staff awareness, use of tubing that eliminates the need for discard, and drawing only the volume necessary for laboratory testing. Bedside microchemistry and protocols for obtaining a laboratory test may further decrease blood loss and eliminate the need for blood transfusions to replace iatrogenic blood loss.

Anemia↗
PubMed1990

Enzyme histochemical methods applied in the brain.

Catalytic enzyme histochemistry offers the possibility to demonstrate enzymes qualitatively and their activities quantitatively in brain sections at those sites where they are localized. To get an appropriate histochemical demonstration of enzymes, requirements are to be fulfilled with respect to the preparation of brain tissue, the detection methods, and the incubation conditions. For enzyme demonstration at the light microscopic level, brain tissue should be frozen as quickly as possible and for those at the electron microscopic level perfusion fixation using low concentrations of aldehydes seems to be best suited. The detection of enzymes in brain sections is preferentially performed by the so-called precipitation reactions with metallic ions, the tetrazolium and the diaminobenzidine methods. The application of these methods was shown in the example of aspartate aminotransferase, glutamate dehydrogenase, and cytochrome c oxidase. In the detection of enzymes incubation conditions should be chosen so that soluble enzymes cannot diffuse out of the sections into the incubation media and that the activities of enzymes are completely demonstrated. On the whole, all the precipitation reactions result in a water-insoluble reaction product which is precipitated at the enzymatic sites in brain sections. Finally, it is shown that scanning microphotometry is a valuable tool for the quantification of enzyme activities in brain sections. It is concluded that catalytic enzyme histochemistry using improved detection methods could be a source of results complementary to those provided by immunocytochemistry and microchemistry.

3,3'-Diaminobenzidine↗
PubMed1994

The use and clinical importance of a substrate-specific electrode for rapid determination of blood lactate concentrations.

OBJECTIVE: To determine the validity and clinical importance of a newly developed amperometric, enzymatic, substrate-specific electrode for the rapid measurement of circulating lactate concentrations. DESIGN: A prospective multiexperiment study. SETTING: The critical care medicine research laboratory, intensive care unit (ICU), emergency department (ED), and general wards of a university-affiliated hospital. PATIENTS: A total of 1218 patients and control subjects were studied on one or more occasions. INTERVENTIONS: Blood lactate concentrations, descriptive data, physiological parameters, and outcome results were determined in various patient populations. MAIN OUTCOME MEASURES AND RESULTS: Experiment 1: Lactate determinations performed with the new substrate-specific electrode were compared with two laboratory reference methods. Blood samples from 80 ICU patients and 165 ED patients formed the basis of this first experiment. There was excellent agreement between the test instrument and the two reference methods as reflected by bias (with reference method 1, 0.19 mmol/L; reference method 2, 0.09 mmol/L), precision (with reference method 1, +/- 0.47 mmol/L; reference method 2, +/- 0.34 mmol/L), and correlation data (with reference method 1, r = .92; reference method 2, r = .98). Experiment 2: The new test microchemistry instrument was used to analyze blood samples from 927 patients. The mean (SE) blood lactate concentrations in the various patient populations were 1.26 (0.04) mmol/L for control subjects (n = 85), 1.52 (0.03) mmol/L for general ward patients (n = 489; P < .001 vs normal subjects), 2.34 (0.15) mmol/L for ICU patients (n = 180; P < .001 vs normal subjects and general ward patients), and 2.44 (0.15) mmol/L for ED patients (n = 173; P < .001 vs normal subjects and general ward patients). None of the normal subjects and only one (0.2%) of 489 nonhypotensive general ward patients had a blood lactate value greater than 4 mmol/L. Circulating lactate concentrations greater than 4 mmol/L were 98.2% specific in predicting the need for hospital admission in patients presenting to the ED. Furthermore, lactate concentrations greater than 4 mmol/L were 96% specific in predicting mortality in hospitalized nonhypotensive patients. Experiment 3: Blood samples from 46 hypotensive ICU and ED patients and from 353 nonhypotensive ICU and ED patients (the latter samples were derived from experiment 2) were analyzed. A statistically significant difference was noted between the mean (SE) lactate concentration in hypotensive patients in the ICU and ED (4.75 [0.75] mmol/L) when compared with nonhypotensive ICU and ED patients (2.28 [0.10] mmol/L; P < .001). Furthermore, blood lactate values greater than 4 mmol/L were 87.5% specific in predicting mortality in hypotensive patients. CONCLUSIONS: Lactate determinations performed using the new test instrument are precise and accurate. Blood lactate concentrations greater than 4 mmol/L are unusual in normal and noncritically ill hospitalized patients and warrant concern. In hospitalized (non-ICU) nonhypotensive subjects, as well as in critically ill patients, a blood lactate concentration greater than 4 mmol/L may portend a poor prognosis.

Blood Chemical Analysis↗
PubMed1994

[Certified clinical pathologists and the program of postgraduate training in clinical pathology].

Clinical chemistry is one of the core subjects required to master for doctors willing to be certified as a specialist in clinical pathology or laboratory medicine. For the past several decades, clinical chemistry has developed so rapidly and widely into many disciplines, such as microchemistry, electrochemistry, immunochemistry, molecular biology and robotics, that it is no more easy even for specialists to understand details in its whole scope nor to utilize the variety of principles, techniques, and equipment. In fact, clinical chemistry today covers such a wide range of laboratory tests as immunoassays, drug monitoring, toxicology, pregnancy tests, and gene diagnosis, in addition to chemical or enzymatic quantification of thousands of substances. Under such enormous circumstances, the program of postgraduate training, particularly in clinical chemistry, should be aimed at raising the capability to fulfill current requirements in medical practice, scientific research, consultative education and laboratory management, as well as to pursue lifelong self-disciplinary education. This capability must be obtained not only in knowledge or skills but also in attitude.

Certification↗
PubMed1995

Photoemission and free electron laser spectromicroscopy: photoemission at high lateral resolution.

The move of photoemission analysis from the macroscopic to the microscopic domain has been accelerated by the advent of new ultrabright synchrotron sources of soft-X-rays. This makes an overview of photoemission spectromicroscopy, photoemission at high lateral resolution, quite timely. The overview begins with the basic concepts and problems, both technical and of data-taking strategy. Then, it presents a small number of examples of results in physics and biology, such as local chemical fluctuations in superconductors, semiconductor interfaces and the microchemistry of biological systems. The presentation includes the first experimental results from two new ultrabright synchrotron facilities: ELETTRA (in Italy) and SRRC (in Taiwan).

Microscopy, Electron↗