Medición de 25-hidroxivitamina D sérica: comparación de dos inmunoensayos / Measurement of 25-hydroxyvitamin D in serum: comparison of two immunoassays

La concentración sérica de 25-hidroxivitamina D (25-OHD) es utilizada como indicador del estado nutricional de Vitamina D (VD). El método más utilizado para medirla es el RIA. El desarrollo reciente de métodos automatizados no radiactivos facilitaría la práctica diaria de laboratorio y el diagnóstico de necesidad de suplementación. Objetivos: Comparar los datos de 25-OHD obtenidos usando un RIA y un método de quimioluminiscencia (QLIA) automatizado disponible en nuestro medio. Materiales y métodos: Concentraciones de 25-OHD se midieron en suero de 45 pacientes: 8 hombres y 37 mujeres; 18 no suplementados y 27 suplementados con VD (n=5 con VD2 y n=22 con VD3). Las mediciones de 25-OHD se realizaron con un RIA y un QLIA automatizado (LIAISON), ambos DiaSorin. Se calcularon los coeficientes de variación intraensayo (CV intra) e interensayo (CV inter) para ambos métodos. Análisis estadístico: la comparación entre métodos se realizó con los programas Analyse-it y Med Calc Se consideró significativa una p<0.05. Resultados: Los CV% intra e inter fueron: para RIA menores de 10,6 y 19,9 vs QLIA menores de 8,0 y 13.2, respectivamente. En la población total y en el subgrupo no suplementado con VD los datos de RIA vs QLIA fueron: coeficiente de correlación de Pearson (0,9259 vs 0,9412), Bias%: (6.1 vs 2.7), coeficiente de concordancia (0,9244 vs 0,9329). Conclusiones: 1) Ambas metodologías son adecuadas para mediciones de 25OHD, especialmente en casos no medicados con VD, 2) La tendencia hacia un mayor bias% observado en pacientes suplementados con VD no parecería ser atribuible a variabilidad metodológica, y sugeriría que la VD exógena o alguno de sus metabolitos interactuaría en forma diferente en la medición de 25-OHD por cada una de las metodologías utilizadas. Mayor número de casos es necesario a fin de confirmar esta hipótesis.

Serum concentration of 25-hydroxyvitamin D (25OHD) is used as an indicator of nutritional status of Vitamin D (VD). The methodolgy more frequently used for its measurement is RIA. The recent development of automated non-radioactive methodologies would help the laboratory daily practice to diagnose the need for supplementation. Objectives: To compare the data of 25-OHD obtained using a RIA and an automated chemiluminescence method (CLIA) automated available in our country. Materials and methods: Concentrations of 25-OHD were measured in serum of 45 patients: 8 men and 37 women, 18 unsupplemented and 27 supplemented with VD (n=5 with VD2 and n=22 with VD3). For 25-OHD measurements we used a RIA and a QLIA under an automated platform (LIAISON), both DiaSorin. We calculated intra-assay (intra) and interassay (inter) coefficients of variation (CV%) for both methods. Statistical analysis: comparison between methods was conducted with Analyse-it and Med Calc softwares; p <0.05 was considered significant. Results: The intra and inter CV% were below 19.9 and 10.6 for RIA vs 8.0 and 13.2 for CLIA, respectively. In the overall population and in the subgroup never supplemented with VD, data for RIA vs CLIA were: Pearson correlation coefficient (0.9259 vs 0.9412), Bias% (6.1 vs. 2.7), concordance coefficient (0.9244 vs 0.9329). Conclusions: 1) Both methods are suitable for measurements of 25OHD, particularly in cases not medicated with VD, 2) The trend toward greater bias% observed in patients supplemented with VD does not appear to be attributable to methodological variability, and suggests that exogenous VD or its metabolites interact differently in the measurement of 25-OHD by each of the methodologies used. A higher number of cases is needed to confirm this hypothesis.

Combined liver and kidney transplantation in a multicenter transplantation program in Chile.

INTRODUCTION: Combined liver and kidney transplantation (CLKT) is an exceptional therapeutic procedure limited to a few diseases with advanced compromise of these organs. Hyperoxaluria type I and polycystic disease are the most frequent indications. The aim of this article was to report our indications and results of CLKT in a multicenter transplantation program in Chile. MATERIAL AND METHODS: Our Excel database was reviewed to select patients who were treated with CLKT between 1993 and July 2004. RESULTS: Among 242 liver transplantations (LT) and 48 kidney transplantations (KT), 7 were CLKT, representing 2.8% of LT and 14.5% of KT. Four patients were women and 3 were male of average age 46.8 years. One patient was a child. Most frequent indications were chronic renal failure associated with terminal liver disease and polycystic disease. One patient needed liver retransplantation due to hepatic vein thrombosis. One patient had a biliary fistula and another had a urinary fistula, treated conservatively. Acute liver rejection took place in 3 cases, 1 of which required antibodies. Two patients died, 1 due to aspergillosis and the other due to vascular complications in the transplanted liver. Actuarial survival rates were 71.4% at 1 and 5 years. Chronic renal failure is not a contraindication to LT. CONCLUSION: CLKT is an acceptable option for these patients.

Child deaths in Virginia, 1996: a review of investigations of sudden, unexpected, or unnatural deaths of children less than age 13.

This study examines the consistency of investigative procedures used by the Office of the Chief Medical Examiner, law enforcement, and child protective services, when investigating the violent, sudden, unexpected, or unnatural deaths of children. The study also assessed the status of communication and cooperation among the investigating agencies, to determine whether improvements in the level of cooperation and communication among the systems recommended by prior legislative studies had been achieved. The subjects of this study were children from birth through age 12 who died a sudden, unexpected, or unnatural death in Virginia in 1996. The findings from this research provide both justification to celebrate the progress that has been made and the stimulus to improve the investigation into the sudden, unexpected, or unnatural deaths of children in Virginia. Data suggested that the level of cooperation and communication among child protective services workers, medical examiners, and law enforcement personnel in Virginia had increased between 1986 and 1996. The results demonstrated that some investigative procedures were consistent, especially within regional boundaries. However, the results also showed that inconsistencies exist in the way some deaths are investigated, and that room for improvement exists.

Practice guideline for forensic pathology. Members of the Forensic Pathology Committee, College of American Pathologists.

The guideline for forensic pathology was prepared by the Forensic Pathology Committee of the College of American Pathologists. The definitional criteria for forensic pathology included in this guideline have been approved both by the House of Delegates and the Board of Governors of the College of American Pathologists. The guideline presents an overview of forensic pathology and an approach to the forensic autopsy and medicolegal death investigation. Emphasis is placed on the role of forensic pathology in maintaining public health, welfare, and safety. The guideline is intended to serve as an educational tool, and its use should be determined by the individual circumstances and settings of specific cases.

Murder-suicide in central Virginia: a descriptive epidemiologic study and empiric validation of the Hanzlick-Koponen typology.

An empiric validation of a proposed typology of murder-suicide events was carried out in the Central District of the Office of the Chief Medical Examiner of Virginia for two cohorts, 1980 to 1984 and 1990 to 1994; use of a single typology allows description of trends in these events over time, a unique aspect of this study. For both cohorts, a total of 53 successful events with 63 victims (116 total deaths) was evaluated. A significant shift in the characteristics of location, perpetrators, and victimology of such events between the two cohorts is demonstrated: events changed from urban, multiple victim events with a majority of white perpetrators to rural, dyadic events in which victims did not live with perpetrators, the majority of whom were black. The results are compared with published data, and the implications for use of this typology as a clinical evaluation tool for prevention are addressed in light of current domestic violence emphases in public health. Additionally, the need for prospective tracking of these events is reiterated and use of the Hanzlick-Koponen typology as the tool for such tracking is suggested.

Distribution of 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyamphetamine (MDA) stereoisomers in a fatal poisoning.

This communication presents the quantitation and differential distribution of the enantiomers of 3,4-methylenedioxymethamphetamine (MDMA) and its physiologically active metabolite 3,4-methylenedioxyamphetamine (MDA) in a fatal poisoning following insufflation of MDMA, cocaine and heroin. Animal studies have demonstrated the stereoselective pharmacokinetics and neurotoxicity of these compounds; however, enantiomeric distributions have not been reported in humans. Quantitation of MDMA and MDA enantiomer was by gas chromatography/mass spectrometry (GC/MS) following chiral derivatization with N-trifluoroacetyl-L-triproyl chloride (LTPC). The decedents' blood concentration of S(+)-MDMA was slightly less than that of R(-)-MDMA (1.3 vs. 1.6 mg/l, respectively), while the S(+)- and R(-)-MDA blood concentrations were identical (0.8 mg/l). Both primary routes of excretion, bile and urine, had greater concentrations of R(-)-MDMA than the S(+) isomer. These fluids also contained twice the concentration of S(+)-MDA than the R(-)-isomer. These data indicate that S(+)-MDMA is metabolized and eliminated faster than R(-)-MDMA. The results appear to support the findings in animals regarding stereoselective metabolism of MDMA.

Positive identification by post-surgical defects from unilateral lambdoid synostectomy: a case report.

The comparison of pre- and postmortem radiographs as a method of identification of unknown human remains is well established in the forensic and radiologic literature. Identification can be based on a single bony feature when there is evidence of prior surgery, trauma or unusual anatomic variation. We present a case in which a positive identification was made using bony changes in the skull secondary to prior surgery for correction of unilateral lambdoid craniosynostosis. The unusual radiographic appearance of the bony defect initially raised the question of trauma and foul play.

Personal identification by radiographic comparison of vascular groove patterns of the calvarium.

A case of forensic identification utilizing the vascular grooves within the skull is presented. The case is unique in that the antemortem radiographs were from childhood, rendering useless the more standard points of comparison. Calvarial vascular grooves represent unique points of comparison when the only available premortem radiographs were obtained during childhood, especially when one is attempting to identify children (living or dead).

Radiologic forensic investigation of fatal gunshot wounds.

The interested radiologist can be a valuable consultant in the investigation of fatal gunshot wounds as well as in the identification of human remains.

New hope for identifying the unidentified. The National Crime Information Center unidentified person/missing person files.

The National Crime Information Center Unidentified Person/Missing Person Files offer computer comparison of descriptive data on unidentified dead and living persons with data entered on missing persons. Completion of a simple, but detailed standard form allows entry of descriptors of physical characteristics, fingerprint classification, dentition, anthropologic and x-ray findings, optic prescriptions, medical devices, surgical procedures, serology, jewelry, and clothes. Medical and law enforcement agencies collect the descriptive data on the unidentified; families and law enforcement agencies collect missing persons information. Entry for both is via law enforcement regional or state NCIC computer terminals. Continuous comparison and cross search of both files is initiated upon entry of either form.

A tetrachloroethylene fatality.

This case report concerns a fatal exposure to tetrachloroethylene at a dry cleaning establishment. A sensitive analytical method was developed and the distribution of the chemical in various fluids and tissues was determined. Although several fatalities from tetrachloroethylene have been reported, little previous quantitative toxicological data have been found in the literature.