Electrophysiological tests in clinical laboratory]

We briefly described recently developed methods for testing cardiac electrophysiological phenomena such as 24-hour Ambulatory ECG, high resolution ECG, body surface mapping ECG, heart rate variability, QT and QT dispersion, and T wave alternans. Of these methods ambulatory ECG monitoring is important and useful for detecting malignant arrhythmias and ischemia attacks, especially in cases of vasospastic angina. Using this method, it is possible to quantitatively analyze arrhythmia and elucidate the pathophysiology of vasospastic angina. The monitoring system is useful not only for diagnosis, but also for assessing treatment efficacy. Heart rate variability is currently used for analyzing the autonomic nervous system; however, the exact meaning of each index still remains to be confirmed. The concept of QT dispersion was recently introduced as an index for detecting dispersion of ventricular repolarization and QT dispersion is still controversial. T wave alternans monitoring has been recently introduced as a new method of assessing the microvolt level of T wave alternans, which has been hypothesized to correlate with the occurrence of arrhythmic events in myocardial infarction. The possible roles of these methods and their applications for clinical practice are discussed.     

Clinical application of clinical laboratory tests

Recent advances in clinical laboratory tests have made it possible to study and clarify the pathogenesis of various diseases from various aspects. Such major advances can be very useful for the treatment and prophylaxis of diseases. Better tests can clarify the mutual relationships among diseases. Unfortunately, however, many clinical tests are not used effectively because they are not adequately understood. On this occasion, we are being given the opportunity to learn about the most recent clinical tests related to blood coagulation and fibrinolysis. These tests offer us the means of elucidating the pathogenesis of diseases. By applying the knowledge gained at this workshop in our clinical practice, we will be able to repay, in a small way, Dr. Matsuo, the chairman, for his efforts in the planning of this workshop.     

Alcohol dehydrogenase interference in clinical chemical laboratory tests

Alcohol dehydrogenase (AD, EC 1.1.1.1 ) activity in serum markedly increases in cases of hypoxic hepatic injury and acute hepatitis. Furthermore, AD can reduce oxidized coenzyme NAD+ to NADH even without substrate such as ethanol. Therefore, AD interferes in clinical chemical tests using the reducing reaction of coenzyme NAD+. We found that AD caused a false positive in serum glucose determination using an enzymatic procedure (hexokinase/glucose-6-phosphate dehydrogenase/NAD+ coupled assay) and increased the blank value of the sample on lactate dehydrogenase (LD) assay using the method recommended method by JSCC (Japanese Society of Clinical Chemistry). We should approve the correction of sample blank reaction in LD activity assay using the method recommended by JSCC as well as the IFCC (International Federation of Clinical Chemistry) method. Also, we should adopt the enzymatic procedures using the reducing of coenzyme NADP+ or without the influence of AD.     

Molecular biology techniques as clinical laboratory tests

The quality of results obtained with molecular biology techniques depends on the control of preanalytical and analytical error associated with such techniques. Preanalytical error can be introduced during the isolation of DNA and RNA. The type of detergent used in cell lysis can affect the amplification of DNA by techniques such as the polymerase chain reaction(PCR). Ribonuclease(RNase) contamination is a serious problem in the isolation of undegraded RNA, and, thus, this enzyme should be inhibited. Anticoagulants used for blood collection can affect the quality of results with molecular biology techniques. The control of contamination from the working environment is essential to the minimization of preanalytical, analytical and postanalytical error. Molecular biology techniques for a wide range of clinical laboratory tests have been established in hospitals such as clinical laboratory tests for infections, molecular diagnoses of leukemia and aberrant genes in metabolism.     

Evaluation of the clinical accuracy of laboratory tests

Fundamental clinical performance of a laboratory test can be described in terms of accuracy, or the ability to correctly classify subjects into clinically relevant subgroups. Accuracy refers to the quality of the information provided by the classification device and should be distinguished from the efficacy, or practical usefulness, of the information. Receiver operating characteristic curves provide a pure index of accuracy by demonstrating the limits of a test's ability to discriminate between alternative states of health over the complete spectrum of operating conditions. If analytical imprecision is removed from the data, the resulting receiver operating characteristic curve represents the inherent biological variation that ultimately limits the clinical accuracy of the test.     

Diagnosis of Herpesvirus hominis infections in a general hospital laboratory.

There is a greatly increased interest in Herpesvirus hominis infections especially those of type 2 associated with genital lesions or neonatal disease. Physicians are eager to confirm the clinical impression with a specific virologic diagnosis such as isolation of the agent and its typing, and type-specific antibody responses. Procedures are reviewed here which permit such studies in general microbiology laboratories equipped for simple cell culture and immunofluorescence. This paper recounts experience with several laboratory methods and evaluates their efficiency and practicability in a general laboratory. Virus isolation was optimal if specimens were obtained from visible lesions early in their evolution and it often provided a specific diagnosis, including typing of the isolate by immunofluorescence, within 24 to 48 h. Estimation of serum antibodies to herpes simplex virus type 1 and 2 by indirect immunofluorescence was more sensitive and perhaps also more specific than by microneutralization test. A pilot study of herpes simplex virus antibody titers in mothers and in the cord blood of the offspring suggested the need to evaluate a possible protective role of high titer antibody in the fetus.     

Diagnostic problems of von Willebrand's disease in a general hospital laboratory

The expression of variant types of von Willebrand's disease can present an elusive diagnostic problem. Bleeding history of patients can vary greatly, as can the results of tests for the components of the Factor VIII complex. Recent advances in characterizing and measuring the factor VIII complex have greatly improved the diagnosis of the variant forms of von Willebrand's disease. However, some of the less sophisticated procedures, which are more readily available, can still be utilized by the routine general hospital laboratory to identify or suspect the occasional case of von Willebrand's disease. These points are exemplified in this report of seven family members who were studied.     

Diabetes and clinical laboratory tests: team medicine

The presentation at this symposium is from the following two perspectives: 1. Indispensability of team medicine for diabetes treatment: Once diabetes has been diagnosed, long-term treatment is essential. Diabetes is often due to a combination of unhealthy lifestyle factors, and treatment therefore requires patients to improve their lifestyles, a certain amount of stoicism also being needed. Patients also have to overcome events in their lives while suffering from diabetes, at the same time as controlling the diabetes, and such events cause stress for the patients, affecting them both psychologically and in terms of lifestyle, so patients' blood sugar levels are disturbed by interactions between stress and lifestyle factors. Medical personnel monitor the progression of numerous diabetic patients, and take different approaches to treatment on the basis of their experience and specialist knowledge. From various perspectives, maintenance of patients' will to continue with treatment is an important aspect of "team medicine". Enabling patients to be treated while feeling themselves to be supported by the treatment team is important, and is linked to empowerment of patients, which is the ultimate objective of the treatment guidelines. 2. Importance of team medicine, illustrated by diabetic nephropathy: If diabetic nephropathy progresses to Stage II or further, deterioration of the patient's condition is unavoidable. Medical personnel often think that the patients also will be concerned about the nephropathy, and will therefore not forget about having been told they have nephropathy. However, it has been found that, when subjective symptoms are absent, patients often do not fully understand the explanation, and forget about the nephropathy. It is therefore essential for medical personnel to appreciate that the risk of nephropathic progression is increased if patients do not remember about having nephropathy.     

EDTA-dependent pseudothrombocytopenia: clinical aspects and laboratory tests

EDTA-dependent pseudothrombocytopenia (EDTA-PTCP) is a phenomenon caused by EDTA-dependent anti-platelet antibody. This antibody induces platelet agglutination in vitro, resulting in a decrease in platelet counts. It is necessary for clinicians to consider the possible presence of PTCP in cases of patients having low platelet counts without any hemorrhagic tendency. In this article, we describe some aspects of EDTA-PTCP including, (1) characteristics of platelet agglutination, (2)possible mechanisms for antibody production, (3) several methods to determine the true platelet number, and also (4) a few similar phenomena induced by antibodies independent of EDTA.     

The clinical pulmonary function tests in the central laboratory section--present and problems of tests

The automatic pulmonary function tests system and the clinical pulmonary function database system by the computer are necessary for the routine of the clinical pulmonary function tests in the central laboratory section. The relationship between the respiratory organs and the pulmonary function disturbances should be analyzed and the respiratory diseases should be diagnosed by using the multiple pulmonary function parameters such as %VC, RV/TLC, %DL etc. in future.     

Medical relevance of laboratory tests. A clinical perspective

To address the role of proficiency testing in the medical usefulness of laboratory tests, nine steps involved in the generation and application of a laboratory test result are identified and discussed: test ordering, patient preparation, specimen, sample, analysis, result, reporting, recognition, and action. Clinical uses of test results are enumerated. Good clinical skills are necessary for optimal test efficiency. Clinicians should improve their selection of tests, pay attention to proper patient preparation, and refine the process of interpretation of test results using disease-based reference ranges and more formal analysis of predictive value. By better definition of the clinical uses of laboratory tests, appropriate attention can be directed to steps in the laboratory domain such as medically relevant goals for accuracy and precision. With clearer understanding of the testing process, proficiency testing for monitoring laboratory performance can be more fully utilized. Audit models should be developed that include assessment of the outcome of the laboratory testing process.     

Recent trend in G-CSF therapy and clinical laboratory tests]

Granulocyte colony-stimulating factor (G-CSF) has strong leukopoietic activity and it is used for patients with leukopenia during leukemia chemotherapy. However, some leukemia cells show a high affinity to G-CSF and are driven to proliferative phase. In our laboratory, we developed two testing methods. 1) Flow cytometric method on G-CSF susceptibility of leukemia cells using FITC-labeled G-CSF, and 2) Immunohistochemical method for detecting the ratio of cells driven from dormant phase to proliferative phase by G-CSF with anti-PCNA antibody and Ki-67 antibody. In MDS patients G-CSF administration induced an increase of cells in proliferative phase. The patients treated with cytosine arabinoside following G-CSF showed hematologically good improvement. A new mode of therapy using G-CSF in combination with other cytokines or antileukemic agents will be developed in the near future for treatment of leukemia patients.