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Results of a nine-laboratory survey of forensic toxicology proficiency.

Toxicological determinations are crucial to coroners' or medical examiners' judgments that drugs are significantly involved in a death. However, differences in laboratory procedures, thoroughness of screening, and limits of detection may result in artifactual differences in the toxicological results and the subsequent interpretations of them. To test this possibility, we conducted a toxicology proficiency-testing survey of nine collaborating laboratories. The results for the proficiency samples point out starting interlaboratory differences in accuracy and precision of detection of drugs. These observed variations in toxicological proficiency may introduce a significant source of error in drug-death statistics and in epidemiological deductions based on these statistics.

Ethanol↗

Reducing substances in urine: a paradigm for changes in a standard test.

Detection of reducing substances in urine has been a standard laboratory procedure for about 50 yr. It is used as a screening test for inborn errors of carbohydrate metabolism. Although the test has poor specificity and most states perform mandatory newborn screening for the common genetic defects, most clinical laboratories still perform this as a reflex test on all pediatric urine samples. We suggest that laboratories should perform this test only at the specific order of a physician and that they should review their test menu frequently to delete tests that no longer have a clinical rationale.

Chemistry, Clinical↗

A pseudo outbreak of tuberculosis.

Three cases of suspected tuberculosis were diagnosed over a ten day period at an oncology unit. Case finding was carried out and six further cases were diagnosed. However, doubts were raised about these diagnoses and a review of the outbreak investigation was carried out. Investigation of laboratory procedures found that the 'outbreak' was likely to be due to a contaminated phenol red solution. This incident highlights the importance of a critical evaluation of outbreak investigations, and the need for close collaboration between clinicians, epidemiologists and laboratory staff.

Child↗

[Economic analysis of neonatal screening for drepanocytosis in metropolitan France].

There is indisputable evidence that mortality and morbidity can be significantly reduced by programmes that screen newborns for sickle cell disease. But in the French epidemiological context, national decision regarding generalization of local screening programmes to all newborns must take into account economic considerations as at-risk populations represent, in most geographic areas, a few percent of the total population. Targeted screening can be considered but raises ethical and practical issues. In order to compare alternative screening strategies, a cost-effectiveness analysis has been performed. The analysis is based on a screening programme of newborns conducted in the south-eastern suburb of Paris. Strategies have been defined in terms of laboratory procedures (isoelectrofocalisation, electrophoresis on citrate agar, high pressure liquid chromatography, BIORAD technique,...) and methods for blood collection (dried paper, micro-tube). An evaluation of all the necessary costs have been performed for each strategy in the biochemistry laboratory in charge of the neonatal programme. Costs have been estimated from detailed observation of physical quantities of capital and labour involved in each case. Evolution of unit and marginal costs according to the level of annual production has been assessed. Effectiveness has been measured in terms of number of sickle cell cases detected. Screening of at-risk babies in Paris region would permit detection of 80 to 215 babies each year at a unit cost per case found varying from 1 to 2,800 US$ (according to hypothesis of prevalence). When compared with other programmes of prevention, results of selected screening of newborns in whole metropolitan France suggest that this action might be discussed by public health authorities.

Anemia, Sickle Cell↗

Preference procedures for testing the abuse liability of drugs in humans.

Drug preference procedures may be used to assess the abuse liability of drugs in human volunteers. These procedures usually measure subjects' choice of a drug versus a placebo, under controlled, double-blind conditions. Depending upon the conditions of the studies (e.g. subject population, environmental conditions of testing), drugs that are known to be abused are also preferred in these laboratory procedures. To assess the abuse liability of an unknown test drug, the frequency of choice of the test drug is compared to choice of a standard drug with known abuse potential: preference for the test drug, relative to the standard, is then taken as an indicator of its relative potential for abuse. A number of methodological variables must be considered when designing and interpreting choice studies, including the characteristics of the subjects, the range of doses tested, whether choices were spaced widely apart (e.g. one a day) or closely together (e.g. one immediately after another), and whether the study was conducted under controlled laboratory conditions or in the subjects' normal daily environments. The conditions for testing the abuse liability of an unknown compound must be selected based on the existing literature with similar, known drugs of abuse.

Choice Behavior↗

Endorphins: naloxone fails to alter experimental pain or mood in humans.

In 30 human subjects, experimental pain was produced by either ischemia or cold-water immersion. In a double-blind procedure, intravenous doses of up to 10 milligrams of naloxone hydrochloride in saline were indistinguishable from similarly administered saline alone. There were no effects on subjective pain ratings, finger plethysmograph recordings, or responses to mood-state questionnaires. These laboratory procedures do not activate any functionally significant pain-attenuating or mood-altering effect of endorphins.

Clinical Trials as Topic↗

[What value does laboratory diagnosis have in acute abdomen?].

1. We found in a prospective study with routine laboratory tests: As a single test only amylase is of certain value, but there are 27% false positive results in peritonitis and intestinal obstruction. 2. Our standardized program can help to evaluate disturbed vital functions and so far improve pre- and postoperative treatment. 3. A high risk is given by simultanously alterated acid-base-balance, blood sugar and creatinine; but these findings are showing shock, not acute abdomen. 4. Laboratory procedures are of no help to the practitioner; they must not delay the early lifesaving operation.

Abdomen, Acute↗

Twin studies of psychopathology: why do the concordance rates vary?

Many current discussions of hereditary factors in psychopathology focus on twin studies as the primary source of evidence supporting the importance of genetic determinants. In summarizing the results of these studies, authors often derive estimates of concordance rates by collapsing across studies and presenting mean or median rates. This practice implicitly assumes that the concordance rates yielded by different studies represent equally reliable estimates of the population mean. The present study evaluates the validity of this assumption. Reports of twin studies of schizophrenia and affective disorder were reviewed. A meta-analysis was conducted to examine the influence of methodological factors on concordance rates. Analyses indicated that both sample-selection and zygosity-determination procedure are systematically associated with concordance rates. For schizophrenia, MZ concordance rates are significantly lower when samples are selected from a twin register as opposed to a psychiatric facility. Lower MZ concordance rates are also yielded by studies that employ laboratory procedures to determine zygosity. Implications of the findings for future research are discussed.

Affective Disorders, Psychotic↗

Laboratory issues: use of nutritional biomarkers.

Biomarkers of nutritional status provide alternative measures of dietary intake. Like the error and variation associated with dietary intake measures, the magnitude and impact of both biological (preanalytical) and laboratory (analytical) variability need to be considered when one is using biomarkers. When choosing a biomarker, it is important to understand how it relates to nutritional intake and the specific time frame of exposure it reflects as well as how it is affected by sampling and laboratory procedures. Biological sources of variation that arise from genetic and disease states of an individual affect biomarkers, but they are also affected by nonbiological sources of variation arising from specimen collection and storage, seasonality, time of day, contamination, stability and laboratory quality assurance. When choosing a laboratory for biomarker assessment, researchers should try to make sure random and systematic error is minimized by inclusion of certain techniques such as blinding of laboratory staff to disease status and including external pooled standards to which laboratory staff are blinded. In addition analytic quality control should be ensured by use of internal standards or certified materials over the entire range of possible values to control method accuracy. One must consider the effect of random laboratory error on measurement precision and also understand the method's limit of detection and the laboratory cutpoints. Choosing appropriate cutpoints and reducing error is extremely important in nutritional epidemiology where weak associations are frequent. As part of this review, serum lipids are included as an example of a biomarker whereby collaborative efforts have been put forth to both understand biological sources of variation and standardize laboratory results.

Behavior↗

Reduction of the rate of false-positive cultures of Mycobacterium tuberculosis in a laboratory with a high culture positivity rate.

Our laboratory, engaged in a prospective study of adult pulmonary tuberculosis, processed on average 1186 sputum samples per year for the detection of Mycobacterium tuberculosis (M. tuberculosis). Approximately 55% of all sputum samples were culture-positive. The study protocol required that all patients had their M. tuberculosis isolates DNA fingerprinted at diagnosis, and at subsequent time points if the patients either failed treatment or presented again with tuberculosis. Over a 22-month period, there were 14 apparent treatment failures from 109 patients who had completed 6 months of therapy. Only two of these were true treatment failures, while the other 12 had DNA fingerprints that were different from those obtained at diagnosis. It was concluded that these 12 cultures represented episodes of laboratory cross-contamination. Retrospective DNA fingerprinting of patient isolates was done so that each patient had at least two independent isolates fingerprinted. This survey revealed that 7.3% of DNA fingerprints were discordant. False-positive cultures with discordant DNA fingerprints generally arose late in chemotherapy and the isolates were usually co-processed with other strongly smear-positive sputum samples. Simple modifications of laboratory procedures were made, and over a following 10.5-month period the false-positive rate was reduced to 2.1%. These modifications did not increase the workload or the cost of processing samples and can thus be used successfully by any laboratory, and particularly by those in resource-poor settings.

Adult↗

Quantitative determination of Escherichia coli from coliforms and faecal coliforms in sea water.

Escherichia coli concentration in sea water was determined by the MUG test after primary growth on membrane filters used to determine total coliforms or faecal coliforms. A good correlation (r = 0.86) was found between E. coli obtained from coliforms versus those from faecal coliforms. Verification procedures showed that all the MUG-positive colonies obtained on both media were E. coli. Evaluation of this data and the literature indicated that this technique for estimation of E. coli in sea water is a useful addition to laboratory procedures without generally increasing the time and the expense of the analysis of recreational water.

Enterobacteriaceae↗

[Changing economic environment of hospitals: management challenges of the 1990s].

The modern hospital is an organization which is influenced by the external environment in which it functions. A major relevant area is the economic environment. In recent years the western world has been facing the challenge of rising costs of health care and an increase in their proportion to the gross national product of most countries. Consequently, hospitals as major providers of health care are under pressure from governments and health insurance companies to cut costs and to "produce" more efficiently. Since hospitals worldwide are finding it hard and painful to function in the new environment in which attitudes to hospitals are changing, a potential managerial-economic crisis may be the next phase. How can the hospital adapt to these changes? First, by adopting managerial attitudes and the tools of the business sector. These include: the strategic planning process, hospital operative autonomy, creating medical-economic responsibility centers as departments, cost-accounting for medical procedures, and case-mix budgeting. Management information systems are necessary during the transition. The hospital information system should include functions at the operative level, such as outpatient visits, and admissions and discharges of patients; and also clinical, diagnostic and laboratory procedures related to the patient case-mix. The second level is a management information system which includes salaries of personnel, case-mix budgeting with variance analysis, prices of procedures and epidemiological data. The authors believe that only the managerial approach combining medical and economic disciplines can meet the challenges of the changing modern economic environment.

Economics↗

Improved procedure for histological identification of osteoid matrix in decalcified bone.

Several improvements on the original method of Yoshiki and coworkers for histological identification of osteoid matrix in decalcified bone are described in this report. The first, fixation of bone with neutral buffered formalin, a popular and stable fixative, should produce better tissue morphology and ensure easy handling in any laboratory. The second is a simple test for aged cyanuric chloride. Aged reagents show poor or no solubility in methanol and have almost no effect on differential staining of osteoid matrix. The third is an application of an organic acid solution in place of neutral EDTA for bone decalcification. Reduced decalcification time with the acid results in rapid preparation of bone sections. Neutral formalin fixation, immersion in the cyanuric chloride solution, decalcification with an organic acid, and hematoxylin and eosin staining, all quite routine laboratory procedures, yield high quality results for identification of osteoid matrix in bone sections.

Animals↗

Detection of hepatitis B virus DNA in serum using synthetic non-radioactive oligonucleotides.

A rapid and simplified technique for detecting hepatitis B virus (HBV) DNA by spot hybridisation in the sera of patients with different clinical forms of HBV infection was investigated using enzyme conjugated synthetic oligodeoxyribonucleotides as probes. These are able to hybridize to the S and C regions of the HBV L(-) DNA strand. When compared with a complete 32P-labelled HBV DNA probe, the synthetic oligonucleotides provided a sensitive and quick method for the routine survey of HBV infection. Moreover, the DNA extraction procedure used allowed the spot hybridisation technique to be applied and read easily and the results obtained within a few hours. It is concluded that synthetic cold probes can be used in hybridisation assays HBV DNA detection as part of current clinical laboratory procedures.

Carrier State↗

[The advance of protection for hazard factor during autopsy].

Recently, the special characteristics of work with SARS require particular attention to the facilities, equipment, policies and procedures involved. In fact, an autopsy also subject prosectors and others to a wide variety of hazards, including bloodborne, aerosolized pathogens and others (for example SARS). Forensic pathologists and other persons in close proximity to an autopsy need personal protective equipment, fourthemore, laboratory procedure and facility design principles of biosafety should be established for the protection of all personnal involved in the work.

Autopsy↗

Value of laboratory investigations in clinical suspicion of cytomegalovirus-induced upper gastrointestinal tract ulcerations in HIV-infected patients.

To assess the value of laboratory investigations for the diagnosis and treatment of cytomegalovirus-induced upper gastrointestinal tract ulcerations, the medical records and biopsy material from HIV-infected patients were reviewed retrospectively during a 12-month period. Clinical diagnosis of cytomegalovirus (CMV) ulceration, based on characteristic endoscopic appearance of extensive ulceration of the mid- to distal esophageal or gastric mucosa and responsiveness to anti-CMV therapy, was compared with laboratory investigations of biopsies. Laboratory procedures consisted of both histopathological examination of the biopsy specimens and viral culture. Twenty episodes in 12 HIV-infected patients could be evaluated. Clinical diagnosis of CMV ulceration appeared to be justified in 14 of 20 episodes (70%), which were confirmed by laboratory investigations. Of the remaining six episodes, which showed partial or no response to anti-CMV therapy, laboratory investigations were negative in two episodes and discrepant in four episodes (histopathology or viral culture positive). A good response to anti-CMV therapy was more frequent in patients whose biopsies proved positive by histopathological examination and/or viral culture than in patients with negative tests (82% versus 0%), which indicates the importance of both investigations. In conclusion, laboratory diagnosis of CMV-induced upper gastrointestinal tract ulcerations supported the diagnosis and decisions on treatment of CMV-induced upper gastrointestinal tract ulcerations.

Cytomegalovirus↗

Immunological procedure for the rapid and specific identification of Coccidioides immitis cultures.

An immunological procedure for the rapid and specific identification of Coccidioides immitis isolates has been developed. The specificity of the procedure is based on the fact that C. immitis produces antigens that are not produced by morphologically similar fungi. The procedure involved the transfer of heavy mold-form inocula to flasks that contained small volumes of brain heart infusion broth. Shake cultures were grown at 25 degrees C on a gyratory shaker at 150 rpm. The concentrated supernatant antigens so obtained from broth cultures were tested in parallel with coccidioidin by a microimmunodiffusion technique against C. immitis antiserum. The ability of the immunological procedure to identify C. immitis cultures was evaluated by testing the supernatant antigens of 166 unknown isolates, many of which, by gross or microscopic examination or both, resembled C. immitis or belonged to the family Gymnoascaceae. Each culture was also identified by conventional laboratory procedures. Comparative evaluation showed that the immunological test for C. immitis was 100% sensitive and specific. The diagnostic precipitin bands that were produced by the interaction of the C. immitis supernatants and antisera were shown to consist of (i) a heat-stable antigen comparable to that active in the tube precipitin test and (ii) two heat-labile antigens, one of which was associated with complement fixation reactivity. With pure cultures, this immunological procedure permitted the identification of C. immitis isolates within 5 days.

Antigens, Fungal↗

Amniocentesis for antenatal diagnosis of genetic defects.

Amniocentesis for intrauterine diagnosis of genetic disease is a safe and highly accurate procedure. This is most fortunate since the timing of the procedure (14 to 16 weeks) and the length of time necessary to cultivate the cells and perform the analysis (3 to 5 weeks) makes it almost mandatory, and almost unique in medicine, that patient management be based on a single non-repeated laboratory procedure. It should be recommended to all patients for whom there is a specific indication for antenatal genetic studies.

Adult↗