Clinical Laboratory Practice Research Articles

Perfil e seguimento dos pacientes portadores de Mycobacterium sp. do Hospital das Clínicas da Universidade Federal de Minas Gerais

INTRODUÇÃO: Em levantamentos feitos no Laboratório de Micobactérias do Hospital das Clínicas da Universidade Federal de Minas Gerais, em anos anteriores, constatou-se que cerca de 42% dos pacientes portadores de micobacterioses não haviam iniciado o tratamento por desconhecerem o diagnóstico. OBJETIVO: Avaliar o perfil dos pacientes portadores de micobacterioses do Hospital das Clínicas da Universidade Federal de Minas Gerais. Descrever o seguimento desses pacientes e sua inserção no sistema de saúde, comparando com a proposta do Programa Nacional de Controle da Tuberculose. MÉTODO: A partir dos registros do Laboratório Central do Hospital das Clínicas da Universidade Federal de Minas Gerais de janeiro a dezembro de 2002, os autores selecionaram os pacientes com diagnóstico bacteriológico de micobacterioses e efetuaram a busca ativa e o seguimento desses pacientes. RESULTADOS: De um total de 66 pacientes,62 (94%) tinham cepas do Mycobacterium tuberculosis e quatro (6%), micobactéria não tuberculosa; quatro desses 62 pacientes (6%) foram transferidos para outras instituições. Após a busca ativa, de um total de 58 pacientes, 37 (63%) estavam curados, 11 (19%) faleceram, sendo que destes, sete (64%) eram positivos para o vírus da imunodeficiência humana (HIV), um (2%) recusou tratamento e nove (16%) não foram encontrados. CONCLUSÃO: Não foi a falta de diagnóstico o que impossibilitou o paciente de receber seu tratamento e, sim, uma estrutura inadequada, com baixa conscientização de todos os envolvidos, demonstrando a desorganização no controle da tuberculose em nível hospitalar. A cura dos pacientes foi aquém da exigida pelo Ministério da Saúde, devido à grande quantidade de soropositivos para o HIV. Os óbitos foram relacionados ao HIV e ao desconhecimento da doença. É fundamental que os profissionais que atuam em nível laboratorial realizem pesquisas operacionais em tuberculose em conjunto com profissionais da área clínica, pois somente dessa forma serão identificadas respostas aos problemas da prática clínico-laboratorial em nosso meio.

A reality check for molecular diagnostics in clinical practice.

Molecular diagnostics, while still evolving, has had a major impact on the practice of laboratory medicine. Overall, the technologies that define molecular pathology as a discipline are universally applied to support clinicians in their healthcare delivery. The molecular pathology laboratory began with the transition of a few molecular biology research tools into the clinical laboratory to the more recent development of new technologies and instrumentation solely for clinical laboratory practice. Concomitantly, the demands for expanded applications to address diagnostic/prognostic, risk assessment, predisposition, and therapeutic testing have far outnumbered the capacity of laboratory delivery systems. As this discipline continues to mature, we must be willing to address issues pertaining to clinical utility, financial responsibility, advanced technologies, training and education. In light of the successes of the Human Genome Project and other genome projects, the number of potential nucleic acid targets for molecular diagnostics continues to increase. Given the current technologies, it is possible for a laboratory to develop ‘in-house’ or ‘laboratory developed’ assays on a routine basis for the purpose of diagnostic testing. In addition, industry is rapidly providing reagents under the analyte specific reagent (ASR) rule of the US Food & Drug Administration (FDA). The critical question is which of these nucleic acid targets will be most useful in patient care? In order for this discipline to move forward, we must better understand the clinical utility of tests offered in the laboratory. For example, most infectious diseases have been characterized by the fulfillment of Koch’s postulates which have most often associated a specific organism with a pathologic process. Therefore, identifying this organism in a patient specimen should indicate the presence of disease. However, molecular diagnostic testing has an unprecedented level of sensitivity and specificity. Latent or dormant infections, the presence of normal flora, and co-infections are all issues related to the clinical utility of a molecular microbiologic test. As another example, through genetic testing or genotyping, we are able to identify a gene target in a patient specimen. This qualitative type of data may not be sufficient without supportive clinical outcomes data. We must better understand mutation spectra, the penetrance of a specific mutation, the role of polymorphisms in normal and disease processes, as well as the association of haplotypes with disease processes. A laboratory test is only as meaningful as its interpretation. In this growing arena of molecular diagnostic tests, the paradigm has shifted from that of a technologic/scientific concern to one of a financial concern. Clearly, molecular diagnostic testing has proven itself. Yet, the addition of highly complex testing in conjunction with lack of replacement of traditional testing is viewed as an increase in laboratory costs. Keep in mind that under certain circumstances, an increase in laboratory cost may in fact result in decreased overall institutional healthcare costs. Reimbursement for molecular diagnostic testing varies considerably from state to state and is dependent upon payor mix and capitation rates.

An improved quality control protocol for ART

Objective: The running of Quality Controls (QC) is not only required by law, but also represents the “gold standard” of good clinical laboratory practice. The ideal QC has built-in controls and standards to validate the observed outcomes. Yet the two standard QC methods commonly utilized in assisted reproductive technologies (ART), the sperm survival assay and the mouse embryo assay, lack such built-in controls. This is due in part to laboratories being reluctant to introduce substances know to deter sperm motility or embryo growth into the ART environment. However, lack of controls may lead to outcomes that are influenced as much by the testing agents (embryos and sperm) as the tested materials themselves. The objective of this presentation is to describe and demonstrate a simple human sperm survival assay, which is not dependent on toxic materials, but includes a set of built-in controls, with expected outcomes, that can be used to validate the QC process.

Stability of NT-proBNP in serum specimens collected in Becton Dickinson Vacutainer (SST) tubes.

Atrial natriuretic peptides, B-type natriuretic peptide (BNP), and C-type peptides play important roles in the cardiovascular system (1)(2)(3). ProBNP is a 108-amino acid peptide that is secreted by the ventricle and is cleaved to physiologically active BNP (amino acids 77–108) and N-terminal fragment NT-proBNP (amino acids 1–76) (3). NT-proBNP is a useful marker for heart failure, including congestive heart failure (4)(5)(6). Recently, Roche Diagnostics marketed an automated NT-proBNP assay on the Elecsys analyzer. The assay uses polyclonal antibodies against NT-proBNP. The concentration of NT-proBNP in healthy individuals depends on both age and gender, with females and elderly patients having higher concentrations. The clinical sensitivity and specificity of NT-proBNP at a cutoff of 125 ng/L for male patients younger than 75 years are 81.6–91.7% (sensitivity) and 86.7–95.7% (specificity), depending on age. The corresponding sensitivity and specificity for female patients are 86.7–94.3% (sensitivity) and 57.8–84.9% (specificity), respectively. The negative predictive value of this test is almost 100% at a clinical threshold of 125 ng/L, according to the package insert (NT-proBNP; Roche Diagnostics). A common practice in clinical laboratories is to draw blood in serum-separator tubes because of the advantage of the barrier gel, which facilitates rapid separation of serum from cellular constituents of blood and prevents hemolysis during prolonged storage. However, measured concentrations of certain drugs, such as phenytoin, phenobarbital, carbamazepine, quinidine, and lidocaine, can be reduced if specimens are stored in Becton Dickinson SSTTM tubes (7). Bush et al.(8) reported reductions in estradiol concentrations when specimens were stored in SST tubes. The purpose of the current study was to determine the stability of NT-proBNP in specimens stored in …

Fluorescence in situ hybridization BCR/ABL fusion signal rate in interphase nuclei of healthy volunteer donors : a test study for establishing false positive rate

Fluorescence in situ hybridization (FISH) using chromosome-specific DNA probes is rapidly becoming a part of clinical laboratory practice. However, as a relatively new clinical test, it is not yet standardized and for practical reasons each laboratory must establish its own criteria. For this purpose we have evaluated the specificity of a dual-color BCR/ABL translocation probe by establishing the range of BCR/ABL fusion-positive scores in a healthy donor group. The false positive rate (FPR), determined by the percent of FISH BCR/ABL fusion-positive cells found in the specimens of healthy donors, was estimated at 2.3% (mean = 1%–4%). Thus the cut-off value for false positive nuclei was set at 5%.

Personnel standards and quality assurance practices of biochemical genetic testing laboratories in the United States.

Abstract Context.—It has been suggested that specific regulation of laboratories performing genetic testing may be needed to ensure standards and quality assurance, and to safeguard the rights of patients with regard to confidentiality and providing informed consent. Previously, a comprehensive analysis of current practices of molecular genetic testing laboratories was conducted, the results of which have assisted in the assessment of the need for regulation and its impact on access to testing. However, a study designed to determine clinical laboratory practices with regard to biochemical genetic testing has not been carried out. Objective.—To collect and analyze data regarding availability of clinical biochemical genetic testing, personnel standards, and laboratory quality assurance practices. Design.—A mail survey of biochemical genetic testing laboratory directors and assignment of a quality assurance score based on responses to genetic testing process items. Setting.—Hospital-based, independent, and r...

Detection of ethambutol-resistant Mycobacterium tuberculosis strains by multiplex allele-specific PCR assay targeting embB306 mutations.

We describe a multiplex allele-specific (MAS)-PCR assay to detect simultaneously mutations in the first and third bases of the embB gene codon 306ATG. These mutations are known to confer ethambutol (EMB) resistance in the majority of clinical Mycobacterium tuberculosis isolates worldwide. The mutated bases are revealed depending on the presence or absence of the respective indicative fragments amplified from the embB306 wild-type allele. Initially optimized on purified DNA samples, the assay was tested on crude cell lysates and auramine-stained sputum slide DNA preparations with the same reproducibility and interpretability of the generated profiles in agarose gel electrophoresis. Since EMB resistance is generally linked to multiple-drug resistance (MDR), the MAS-PCR assay for EMB resistance detection can be used in clinical laboratory practice in areas with a high prevalence and a high transmission rate of MDR-EMB-resistant tuberculosis.

Capabilities That Could Change Clinical Laboratory Practice

Capabilities That Could Change Clinical Laboratory Practice

Blood transfusion costs by diagnosis-related groups in 60 university hospitals in 1995.

Transfusion services are frequently challenged to initiate efforts to reduce blood transfusion costs. One approach is to analyze blood transfusion costs for individual medical and surgical Diagnosis-Related Groups (DRGs). Rank ordering of DRGs by transfusion costs and interinstitutional comparisons of these costs may lead to the selection of DRGs for further analysis of the process of blood transfusion. Common DRGs (n = 486) that were related to discharges in 1995 were analyzed from 60 university hospital members of the University HealthSystems Consortium (UHC). Cost data were tabulated by using cost-to-charge ratios reflecting all aspects of blood transfusion-related costs of participating institutions. Of these 486 DRGs, 471 had identifiable mean blood costs, and 34 had median blood costs, mostly for surgical conditions. Transfusion costs represented a small proportion (< or = 1%) of total hospitalization costs for most DRGS: Nonetheless, millions of dollars were spent on blood transfusion, and for the most expensive DRGs, the costs ranged from 5.0 to 8.6 percent of total hospitalization costs. Transfusion costs are more variable for the DRGs with the lowest transfusion costs than for those with the highest transfusion costs. Members of the UHC may utilize such analyses to identify surgical or medical diagnoses with transfusion costs at variance with the group norm. These DRGs could then be targeted for further evaluation of components contributing to high costs, for possible alterations in physician or clinical laboratory practices. Considering those conditions with the highest cumulative transfusion costs (e.g., BMT, liver transplant, acute leukemia, and cardiothoracic procedures), changes in transfusion practices that affect these particular patient categories may have a significant impact on global blood transfusion costs.

The laboratory in the investigation of andropause: The contribution of hormonal measures to andropause diagnosis

Bioavailable testosterone assay constitutes a major improvement in clinical laboratory practice compared with the classic total testosterone assay for the identification of patients with partial androgen deficiency. It is also clear that clinical laboratories are not faced with obvious markers of primary hypogonadism but have to contribute to identifying a more subtle hypogonadal condition that does not involve testosterone uniquely; it probably involves a more complex endocrine condition with multiple components. In the near future, other markers may appear that may improve the diagnosis and treatment of men with partial androgen and other deficiencies.

Application of mixed cell lines for the detection of viruses from clinical specimens

Virus isolation usually requires specimen inoculation into a conventional cell culture tube and daily observation for cytopathic effect (CPE). This process can take from several days to weeks before the results are available. Direct viral antigen detection by staining clinical specimens with specific monoclonal antibodies (MAbs) has contributed enormously to patient management and institution of antiviral therapy. The shell vial technique which combines centrifugation with MAb staining has further reduced the time for virus detection. However, due to the limited optimum sensitivity of a single cell line preparation for different viral pathogens, several different cell lines along with primary monkey kidney (PMK) cells are often included for conventional tube or shell vial culture. This practice is both costly .and time consuming and the preparation of PMK cells may result in cells contaminated with endogenous viruses (1,2). Cost-containment has become a top priority in clinical laboratory practice. For a diagnostic virology laboratory to become cost-effective, use of a mixture of two cell lines in a single diagnostic unit can be a major contribution. If the mixed cell culture works properly, it will increase the number of cultivable viruses, reduce the requirement for multiple cell units, and thereby decrease reagent costs. Several factors determine whether or not a particular mixed-cell unit will perform as expected. The cells lines that are combined should (i) complement each other to broaden the range of viruses detected, (ii) be able to survive in a single unit without interference, (iii) maintain an expected ratio of cells throughout the usable period, and (iv) exhibit the same susceptibility of individual cells to viruses being cultured or even show a synergistic effect. In collaboration with Diagnostic Hybrids Inc. (Athens, OH), we have successfully produced several mixed cell cultures that meet these criteria.

Improvement in physician's office laboratory practices, 1989-1994.

In 1986 and 1989, the Centers for Disease Control and Prevention sponsored institutes on Critical Issues in Health Laboratory Practice. It was noted during the institutes that physician's office laboratories were a rapidly emerging site for clinical laboratory testing, yet no comprehensive data were available regarding the practice of clinical laboratory medicine in physician's office laboratories. As a mechanism to begin addressing this void, the Centers for Disease Control and Prevention added questions on clinical laboratory practice to the National Ambulatory Medical Care Survey, a national probability sample of ambulatory care provided by office-based physicians. Data were collected for survey years 1989, 1991, 1993, and 1994. Each survey was conducted among a nationally representative, random sample of office-based physicians who provide ambulatory patient care. Sample physicians were enlisted using both mail and telephone contacts. Clinical laboratory data were obtained via telephone by trained field representatives. Weighted univariate and multivariate analyses were performed on responses from each of the 4 survey years. Analyses were repeated after combining survey responses from years 1989 and 1991 and 1993 and 1994 as representative of physician's office laboratory practices before and after implementation of the Clinical Laboratory Improvement Amendments of 1988 (CLIA '88) final rule in 1992. Quality laboratory practice indicators showed significant increases during the study interval, with implementation of the CLIA '88 final rule in 1992 playing a pivotal role. Relative to 1992, enrollment in proficiency testing programs increased from 32.4% to 52.7% (P<.001), use of daily quality control samples increased from 79.2% to 89.0% (P<.001), and use of daily quality control with written instructions for action following a questionable quality control result (quality control with action step documentation) increased from 62.6% to 77.2% (P<.001). The presence of a medical technologist or technician in the office laboratory was also significantly and independently associated with each of the quality indicators. Although the percentage of physician's offices performing on-site testing decreased from 56% to 45% during the survey interval, overall testing volume appeared unchanged. The quality of clinical laboratory practice in physician's office laboratories improved during the study interval (1989-1994) as measured by the quality indicators used in the study. The association of this improvement with implementation of the CLIA '88 final rule and the presence of a trained laboratory professional in the testing site indicate the importance of minimum practice standards and professional expertise in ensuring use of quality laboratory practices. Overall test volume appeared to be stable despite a decreased proportion of physician's offices at which on-site testing was performed.

Determination of MIC Quality Control Ranges for ABT-733, a Novel Ketolide Antimicrobial Agent

Determination of MIC Quality Control Ranges for ABT-733, a Novel Ketolide Antimicrobial Agent

Laboratory diagnosis of patients with acute chest pain.

The enzyme activities of creatine kinase (CK), its isoenzyme MB (CK-MB) and of lactate dehydrogenase isoenzyme 1 (LD-1) have been used for years in diagnosing patients with chest pain in order to differentiate patients with acute myocardial infarction (AMI) from non-AMI patients. These methods are easy to perform as automated analyses, but they are not specific for cardiac muscle damage. During the early 90's the situation changed. First creatine kinase MB mass (CK-MB mass) replaced the measurement of CK-MB activity. Subsequently cardiac-specific proteins troponin T (cTnT) and troponin I (cTnI) appeared on the scene, displacing LD-1 analysis. However, troponin concentrations in blood increase only from four to six hours after onset of chest pain. Therefore a rapid marker such as myoglobin, fatty acid binding protein or glycogen phosphorylase BB could be used in early diagnosis of AMI. On the other hand, CK-MB isoforms alone may also be useful in rapid diagnosis of cardiac muscle damage. Myoglobin, CK-MB mass, cTnT and cTnI are nowadays widely used in diagnosing patients with acute chest pain. Myoglobin is not cardiac-specific and therefore requires supplementation with some other analyses such as troponins to support the myoglobin value. Troponins are very highly cardiac-specific. Only the sera of some patients with severe renal failure, which requires hemodialysis, have elevated cTnT and/or cTnI without there being any evidence of cardiac damage. On the other hand, the latest studies have shown that elevated troponin levels in sera of hemodialysis patients point to an increased risk of future cardiac events in a similar manner to the elevated troponin values in sera of patients with unstable angina pectoris. In addition, the bedside tests for cTnT and cTnI alone or together with myoglobin and CK-MB mass can be used instead of quantitative analyses in the diagnosis of patients with chest pain. These rapid tests are easy to perform and they do not require expensive instrumentation. For routine clinical laboratory practice we suggest that in diagnosis of patients with chest pain, myoglobin and CK-MB mass measurements should be performed whenever they are requested (24 h/day) and cTnT or cTnI on admission to the hospital and then 4-6 and 12 hours later.

Homocysteine: cholesterol of the 90s?

Homocysteine is a sulfur-containing amino acid generated through the demethylation of methionine. It is largely catabolized by trans-sulfuration to cysteine but it may also be remethylated to methionine. Dubbed ‘the cholesterol of the 90s’ by the lay press, homocysteine is thought to be thrombophilic and to damage the vascular endothelium. Total plasma homocysteine (tHcy) is now established as a clinical risk factor for coronary artery disease, as well as other arterial and venous occlusive disease in adult populations. Regulation of homocysteine is dependent on nutrient intake, especially folate, vitamins B6 and B12. It is also controlled by common genetic variations (polymorphisms) in how vitamins are utilized as cofactors in the reactions controlling homocysteine metabolism. Moreover, concentrations are age- and sex-dependent and are altered by renal function, hormonal status, drug intake and a variety of other common clinical factors. Considerable care must be taken in assaying tHcy. Plasma should be separated shortly after collection, to avoid artifactual increases due to synthesis by blood cells in vitro. Reference methods have not been validated and criteria for establishing reference ranges should take into account the variable prevalence of physiological hyperhomocysteinemia. Determination of tHcy should probably be limited to centres with relevant expertise and ability to maintain the high degree of precision required for reliable interpretation. Molecular testing for the genetic polymorphisms is still in the research phase but the ease and reliability of molecular diagnosis will speed its introduction into clinical laboratory practice – particularly in relation to diagnosis of thrombophilic disorders. Clinical research initiatives are being driven by the benefit that should be achieved by correction with vitamin supplements, particularly folate and B vitamins, but it must be recognized that prospective controlled studies to validate clinical benefit are only now being initiated. At the moment, it is safe to say that hyperhomocysteinemia is one of the few prevalent biochemical risk factors for thromboembolic disease that might be corrected by vitamin supplements. Such a possibility lies behind the growing momentum to recommend increased supplements of folate and B vitamins to at-risk population and patient groups today.

Capillary zone electrophoresis: An additional technique for the identification of hemoglobin variants

Two capillary zone electrophoresis kits (Hb A2 and Hb A1c) were tested for confirmation and identification of hemoglobin variants. The capillary zone electrophoresis experiments were performed at pH 4.7 (Hb A1c kit) and 8.7 (Hb A2 kit) in a 24 cm uncoated fused silica capillary tube (25 μm I.D.). Normal hemoglobins and common hemoglobin variants, including Hbs S, D-Punjab, C, E, O-Arab, and G-Philadelphia, were successfully separated by both methods within a few minutes. Both systems provided completely different elution profiles of normal and abnormal hemoglobin fractions tested and were complementary. The inter-assay coefficient of variations of the migration times of hemoglobin variants were less than 1.0 and 1.3% by the Hb A2 and Hb A1c, respectively. This permits a higher resolution of some hemoglobin variants in low concentrations, like Hb S in newborns, compared with conventional electrophoresis methods. The present capillary zone electrophoresis methods are sensitive, rapid, not labor intensive, and highly selective for the separation of hemoglobin variants. Combination of both methods with some conventional methods, such as isoelectrofocusing, allows identification of Hbs C, E, O-Arab, S, and D-Punjab, as well as their quantification. We have demonstrated that the conventional electrophoresis methods (electrophoresis at pH 6.5 in citrate agar gel and electrophoresis at pH 8.6 on cellulose acetate) can be advantageously replaced by the present capillary zone electrophoresis methods in a clinical laboratory practice for the detection and quantification of hemoglobin variants.

Separation of human globin chains by micellar electrokinetic capillary chromatography

A new separation method of human globin chains by micellar electrokinetic capillary chromatography (MECC) is described. In this method, a 25 m M phosphate buffer (pH 2.5) containing 7 M urea and 1% (w/v) reduced Triton X-100 buffer system was used. All experiments were performed in a 47 cm×50 μm I.D. uncoated fused-silica capillary. The separation voltage was set at 19 kV. Normal globin chains derived from normal adults and newborns, α, β, δ, Gγ and Aγ globin chains as well as common variant globin chains were successfully separated within 20 min. High reproducible migration times of globin chains (CVs of intra- and inter-assay were less than 1% and 2% respectively), and quantification of Gγ and Aγ chains (CVs for intra- and inter-assay were less than 5% and 10%, respectively) were obtained. This new MECC method provides primary information on structural modification of globin chains. It can be an important diagnostic tool in clinical laboratory practice in the field of hemoglobinopathies.

They Use Enzymes for Everything!

This year marks the 50th anniversary of the American Association for Clinical Chemistry. In tribute to this semicentenary, this journal will reflect on its published achievements over the past five decades.1 Our Editor has recently enumerated some of the publications that have had an impact on the field, as demonstrated by a solid history of citation (1). This editorial, the first in a projected series of four to appear this year, will reflect on those papers that have advanced the area of enzymes and protein markers–now a regular feature in these pages. Of the papers that have achieved citation fame (1), approximately 20% deal with clinical enzymology (2)(3)(4)(5)(6)(7). Yet another 20% focus on the use of enzymes as analytical tools, e.g., those listed in references 8–10 . In the first volume of this journal (1954), enzyme measurements as markers of human disease were the focal points of only two papers. The topics were amylase and arginase. None characterized the use of enzymes as analytical reagents, reflecting clinical laboratory practice of the day. Today, in most laboratories, of the two dozen “routine” chemistry analytes, nearly two-thirds are often determined by enzymatic analyses. This is largely the result of the explosion in the number of studies of enzymes as catalysts, markers of disease, and tools for the laboratorian over the 1960s and the subsequent two decades. This growth phase in enzymology was concurrent with the growth of the practice of clinical chemistry and of the AACC. Without these advances, modern clinical laboratory analyses would not be possible. The detection of proteins in serum by their catalytic activity as a reporter of tissue damage is a cornerstone of medical laboratory analyses. The uses of a wide variety of enzymes from a still …

Flow cytometric analysis of lymphocyte subsets in migraine patients during and outside of an acute headache attack.

We have conducted flow cytometric studies of two subsets of lymphocyte markers in groups of migraineurs during (n = 12; group B) and outside (n = 10; group C) of a migraine without aura attack (total n = 22; group A), including a group of patients tested in both of these phases (n = 5; group D), and compared these results with those obtained from a population of age-comparable, sex- and race-matched healthy volunteers (n = 12; group E). Comparison of the first set of lymphocytes (CD3+CD16 + 56+, CD3-CD16 + 56+, CD3-CD19+, CD3+CD19+, and CD3+HLA - DR+) between the patients in group A and the controls (group E) showed differences, reflecting greater group A percentages of CD3+CD16 + CD56+ and CD3-CD19+ lymphocytes. Furthermore, these differences reached statistical significance only for the CD3+CD16 + CD56+ lymphocytes, and then solely for the patients in group C (Scheffe's test, p < 0.05). Paired analysis of the above lymphocyte markers for subjects in group D failed to show significant differences between patients when they were having and not having a migraine attack, raising the possibility that results from a larger study could show meaningful increases in percentages of CD3+CD16 + CD56+ lymphocytes as one of the immune parameters useful for differentiating migraineurs from controls. Comparison of a second set of lymphocyte markers (CD19+CD5+, CD20+CD72-, CD20-CD72+, CD20+CD72+) among either the different groups of patients or between the patients and controls failed, however, to show statistically significant differences, emphasizing the apparent specificity of the findings described above for CD3+CD16 + CD56+ lymphocytes. Our results, albeit of a preliminary nature, suggest the occurrence of significant, differential changes in lymphocyte subset immunophenotyping between groups of pain-free migraineurs and patients during an acute migraine episode or controls. Corroboration of these findings may prove useful in clinical laboratory practice to identify changes in immunological parameters specifically associated with migraineurs, and help towards a better understanding of the etiology and pathophysiology of this condition.

81 A data management system allowing multi-institutional clinical trials to deliver secure communications and Good Clinical Laboratory Practice Standards on the World-Wide Web

81 A data management system allowing multi-institutional clinical trials to deliver secure communications and Good Clinical Laboratory Practice Standards on the World-Wide Web