Cinematic rendering of a burst sagittal suture caused by an occipito-frontal gunshot wound.

The computed tomography (CT) scan of a 19-year-old man who died from an occipito-frontal gunshot wound presented an impressive radiating fracture line where the entire sagittal suture burst due to the high intracranial pressure that arose from a near-contact shot from a 9 mm bullet fired from a Glock 17 pistol. Photorealistic depictions of the radiating fracture lines along the cranial bones were created using three-dimensional reconstruction methods, such as the novel cinematic rendering technique that simulates the propagation and interaction of light when it passes through volumetric data. Since the brain had collapsed, depiction of soft tissue was insufficient on CT images. An additional magnetic resonance imaging (MRI) examination was performed, which enabled the diagnostic assessment of cerebral injuries.

A descriptive and validation study of a predictive model of severity of SARS-COV-2 infection.

Objectives: The strain the SARS-COV-2 pandemic is putting on hospitals requires that predictive values are identified for a rapid triage and management of patients at a higher risk of developing severe COVID-19. We developed and validated a prognostic model of COVID-19 severity. Methods: A descriptive, comparative study of patients with positive vs. negative PCR-RT for SARS-COV-2 and of patients who developed moderate vs. severe COVID-19 was conducted. The model was built based on analytical and demographic data and comorbidities of patients seen in an Emergency Department with symptoms consistent with COVID-19. A logistic regression model was designed from data of the COVID-19-positive cohort. Results: The sample was composed of 410 COVID-positive patients (303 with moderate disease and 107 with severe disease) and 81 COVID-negative patients. The predictive variables identified included lactate dehydrogenase, C-reactive protein, total proteins, urea, and platelets. Internal calibration showed an area under the ROC curve (AUC) of 0.88 (CI 95%: 0.85-0.92), with a rate of correct classifications of 85.2% for a cut-off value of 0.5. External validation (100 patients) yielded an AUC of 0.79 (95% CI: 0.71-0.89), with a rate of correct classifications of 73%. Conclusions: The predictive model identifies patients at a higher risk of developing severe COVID-19 at Emergency Department, with a first blood test and common parameters used in a clinical laboratory. This model may be a valuable tool for clinical planning and decision-making.

Virtopsy of a gravid Boa constrictor using computed tomography and magnetic resonance imaging.

This article presents radiologic examinations of a deeply sedated Boa constrictor with boid inclusion body disease (BIBD) as an adjunction to the subsequent necropsy. This method is known as virtopsy. The Boa constrictor in the present case was gravid. Computed tomography (CT) allowed for the detailed depiction of a fetal skeleton at the rear end of the adult snake. Furthermore, tiny gas formation was detected inside the cranium of the fetus, which was deemed a radiologic sign for decomposition. Magnetic resonance imaging (MRI) delineated the soft tissue at high resolution. This article illustrates the use of CT and MRI for the examination of a gravid Boa constrictor before necropsy and demonstrates the detection of "normal" postmortem findings leading to the confirmation of fetal death in situ.

Trends in Diagnosis of Alpha-1 Antitrypsin Deficiency Between 2015 and 2019 in a Reference Laboratory.

Background: Alpha-1 antitrypsin deficiency (AATD) remains largely underdiagnosed despite recommendations of healthcare institutions and programmes designed to increase awareness. The objective was to analyse the trends in AATD diagnosis during the last 5 years in a Spanish AATD reference laboratory. Methods: This was a retrospective revision of all alpha-1 antitrypsin (AAT) determinations undertaken in our laboratory from 2015 to 2019. We analysed the number of AAT determinations performed and described the characteristics of the individuals tested, as well as the medical specialties and the reasons for requesting AAT determination. Results: A total of 3507 determinations were performed, of which 5.5% corresponded to children. A significant increase in the number of AAT determinations was observed from 349 in 2015 to 872 in 2019. Among the samples, 57.6% carried an intermediate AATD (50-119 mg/dL) and 2.4% severe deficiency (<50 mg/dL). The most frequent phenotype in severe AATD individuals was PI*ZZ (78.5%), and aminotransferase levels were above normal in around 43% of children and 30% of adults. Respiratory specialists requested the highest number of AAT determinations (31.5%) followed by digestive diseases and internal medicine (27.5%) and primary care physicians (19.7%). The main reason for AAT determination in severe AATD adults was chronic obstructive pulmonary disease (41.7%), but reasons for requesting AAT determination were not reported in up to 41.7% of adults and 58.3% of children. Conclusion: There is an increase in the frequency of AATD testing despite the rate of AAT determination remaining low. Awareness about AAT is probably increasing, but the reason for testing is not always clear.

Identification of new viral variants specific to the honey bee mite Varroa destructor.

Large-scale colony losses among managed Western honey bees have become a serious threat to the beekeeping industry in the last decade. Multiple factors contribute to these losses, but the impact of Varroa destructor parasitism is by far the most important, along with the contribution of some pathogenic viruses vectored by the mite. So far, more than 20 viruses have been identified infecting the honey bee, most of them RNA viruses. They may be maintained either as covert infections or causing severe symptomatic infections, compromising the viability of the colony. In silico analysis of available transcriptomic data obtained from mites collected in the USA and Europe, as well as additional investigation with new samples collected locally, allowed the description of three RNA viruses, two of them variants of the previously described VDV-2 and VDV-3 and the other a new species reported here for the first time. Our results showed that these viruses were widespread among samples and that they were present in the mites as well as in the bees but with differences in the relative abundance and prevalence. However, we have obtained strong evidence showing that these three viruses were able to replicate in the mite, but not in the bee, suggesting that they are selectively infecting the mite. This opens the door to future applications that may help controlling the mite through biological control approaches.

Design and validation of a questionnaire in Spanish language for software usability evaluation.

BACKGROUND: Usability is an essential characteristic of software development, which needs to be evaluated mainly through questionnaires. However, the questionnaires available in Spanish are limited and not available for most software's developers and users. OBJECTIVES: This work aimed to design and validate a new questionnaire to evaluate software usability, considering the characteristics of efficiency, effectiveness, and satisfaction as defined by the International Standards Organization. METHODS: The Software Usability Assessment Questionnaire or SUAQ in Spanish language was designed and validated using Kendall's coefficient, Cronbach's Alpha, Factorial Analysis and Scree test. RESULTS: The questionnaire's validation was carried out by five experts through an evaluation of the clarity, coherence, and relevance of the proposed items. Once the questionnaire was administered to 95 participants, an overall reliability value of Cronbach's alpha of 0.839 was obtained. The factorial analysis is viable since a value of 0.757 was found in the Kaiser-Meyer-Olkin (KMO) test, and a significant value was obtained in Bartlett's sphericity test. CONCLUSIONS: The proposed questionnaire proved to be valid and reliable, and therefore, suitable to evaluate software usability in the Spanish language.

Alteraciones de la piel del paciente con enfermedad renal crónica avanzada. Una revisión sistemática / Skin alterations in patients with advanced chronic kidney disease. A systematic review

Objetivo: Conocer las principales alteraciones de la piel, así como su prevalencia, en los pacientes con Enfermedad Renal Crónica Avanzada. Material y Método: Se ha realizado una revisión sistemática a través de las bases de datos de PubMed, Cochrane, Scopus y Google Académico. Se incluyeron artículos científicos escritos en inglés y español. Se analizaron los artículos que trataban sobre las alteraciones en la piel en el paciente con Enfermedad Renal Crónica Avanzada y/o en tratamiento con diálisis. Resultados: Se han incluido 32 artículos publicados entre el año 2008 y 2018: 7 revisiones sistemáticas, 3 de tipo experimental y 22 de tipo observacional. Las alteraciones cutáneas aparecen en la mayoría de los pacientes en prediálisis y en tratamiento con diálisis, en mayor o menor grado. La mayoría de alteraciones de la piel descritas han sido, xerosis, prurito e hiperpigmentación. La mayor complicación relacionada con la alteración de la piel ha sido la calcifilaxis; siendo las variables más influyentes en la aparición de estas lesiones, el tipo de tratamiento dialítico, las enfermedades asociadas y falta de adherencia a la dieta prescrita. Conclusiones: Las alteraciones en la piel están presentes en la mayoría de los pacientes con Enfermedad Renal Crónica Avanzada y en diálisis, predominando la xerosis como la alteración más frecuente, siguiéndole el prurito y la hiperpigmentación. La complicación más grave relacionada con las alteraciones de la piel es la calcifilaxis, encontrándose asociada a altos niveles de fósforo sérico. No existen protocolos estandarizados para el manejo de las alteraciones cutáneas en estos pacientes

Objective: To know the main alterations of the skin, as well as its prevalence, in patients with Advanced Chronic Kidney Disease. Material and Method: A systematic review was carried out through searches in the PubMed, Cochrane, Scopus and Google Scholar databases. Scientific articles written in English and Spanish were included. Articles that addressed skin alterations in patients with Advanced Chronic Kidney Disease and/or on dialysis treatment were analyzed. Results: 32 articles published between 2008 and 2018 were included: 7 systematic reviews, 3 intervention studies and 22 observational studies. To a greater or lesser degree, skin disorders appear in most patients on pre-dialysis and on dialysis treatment. Most of the skin disorders described were xerosis, pruritus and hyperpigmentation. The major complication related to the skin alteration was calcifilaxis; being the type of dialysis treatment, the associated diseases and lack of adherence to the prescribed diet, the most influential variables in the appearance of the lesions. Conclusion: Skin alterations are present in many patients with Advanced Chronic Renal Disease and on dialysis, being xerosis the most frequent alteration, followed by pruritus and hyperpigmentation. The most serious complication related to skin alteration is calcifilaxis, being associated with high levels of serum phosphorus. There are no standardized protocols for the management of skin disorders in these patients

Calidad de vida de los pacientes en diálisis. Revisión sistemática / Quality of life of dialysis patients. Systematic review

Objetivo: Identificar las variables más influyentes en la calidad de vida relacionada con la salud en pacientes en diálisis, identificando los instrumentos de medida más utilizados. Material y Método: Se ha realizado una revisión sistemática en las bases de datos PubMed, Scopus, Google Académico y Scielo. Se han incluido artículos científicos en inglés y español. Se han analizado artículos que tratan la calidad de vida relacionada con la salud en pacientes en diálisis, excluyendo aquellos artículos que no aportaban resultados concluyentes, en población pediátrica y en los que se analizaba este parámetro exclusivamente en pacientes trasplantados. Resultados: Se han incluido 36 artículos publicados entre 2009-2019. La calidad de vida relacionada con la salud aparece disminuida en todos los pacientes en diálisis, más concretamente en hemodiálisis. Las variables más influyentes en la disminución de la calidad de vida relacionada con la salud del paciente en diálisis, son: sexo femenino, edad avanzada, no poseer un núcleo familiar, estudios primarios, y afectación de la situación laboral en pacientes en edad para trabajar; además de comorbilidad asociada a la patología renal, ansiedad y depresión, presencia de dolor y con grado de dependencia alto. Conclusiones: La disminución de la calidad de vida está presente en la mayoría de los pacientes de diálisis, con más frecuencia en hemodiálisis. Respecto a los instrumentos de evaluación empleados, el más utilizado es el KDQOL-SF. Esta pérdida de la calidad de vida se relaciona con ser mujer, edad avanzada, comorbilidad asociada, dolor con limitaciones, presencia de ansiedad y/o depresión y mayor dependencia

Objective: To identify the most influential variables in health-related quality of life in dialysis patients, identifying the most common measuring instruments. Material and Method: A systematic review was carried out in the PubMed, Scopus, Google Scholar and Scielo databases. Scientific articles in English and Spanish have been included. Articles that evaluate health-related quality of life in dialysis patients, excluding those articles that did not provide conclusive results, in the pediatric population and those that addressed this parameter exclusively in transplanted patients, were analyzed. Results: 36 articles published between 2009-2019 have been included. Health-related quality of life appears diminished in all dialysis patients, more specifically in hemodialysis. The most influential variables in the decrease of the health-related quality of life of the dialysis patient are: female sex, older age, not having a family nucleus, primary studies, and affectation of the employment situation in patients of working age; in addition to comorbidity associated with kidney disease, anxiety and depression, presence of pain and high degree of dependence. Conclusions: The decrease in the quality of life is present in many dialysis patients, more frequently in hemodialysis. Regarding the evaluation instruments used, the most used is the KDQOL-SF. This loss of quality of life is related to being a woman, old age, associated comorbidity, pain with limitations, presence of anxiety and/or depression and greater dependence

Relación entre la calidad de vida relacionada con la salud y la ansiedad/depresión en pacientes en hemodiálisis crónica / Relationship between health-related quality of life and anxiety / depression in patients on chronic hemodialysis

Objetivo: El objetivo del presente estudio fue analizar la Calidad de Vida Relacionada con la Salud en pacientes hemodiálisis y su relación con la ansiedad y la depresión. Pacientes y Método: Se estudiaron 122 pacientes en hemodiálisis, con una edad de 66,47+/-14,2 años (34,4% mujeres). Se realizó un estudio descriptivo y transversal, en el área de influencia del Servicio de Nefrología del Hospital Reina Sofía de Córdoba. Se estudió la Calidad de Vida Relacionada con la Salud (cuestionario KDQOL-SF), Ansiedad y Depresión (cuestionario Escala de Ansiedad y Depresión de Goldberg) y la comorbilidad asociada. Resultados: En el KDQOL, las dimensiones más afectadas fueron: Situación Laboral, Carga de la Enfermedad Renal, Función Sexual y Sueño. En las dimensiones del cuestionario SF, las áreas más afectadas fueron: Rol Físico, Salud General y Función Física. El 42,6% de los pacientes presentaron probabilidad de tener ansiedad, el 52,5% depresión, y el 32,8% presentaban la probabilidad de padecer ambas alteraciones (ansiedad y depresión). La ansiedad y la depresión se asociaron de forma significativa a peores puntuaciones en todas las dimensiones del cuestionario KDQOL-SF. Conclusiones: Los pacientes en hemodiálisis presentan peor calidad de vida que la población sana de referencia, especialmente en las dimensiones Carga de la enfermedad renal, Sueño, Salud general, Vitalidad, Función física y Rol físico. Esta disminución de la calidad de vida está relacionada con la probabilidad de padecer ansiedad y/o depresión. El sexo femenino, la comorbilidad asociada y el tiempo en hemodiálisis, se asocian también a peor calidad de vida

Objective: The aim of the present study was to analyze the health-related quality of life in hemodialysis patients and their relationship with anxiety and depression. Material and Method: One hundred and twenty-two hemodialysis patients were studied, with an age of 66.47 +/- 14.2 years (34.4% women). A descriptive and cross-sectional study was carried out in around the Nephrology Unit of the Reina Sofía University Hospital of Cordoba. The health-related quality of life (KDQOL-SF questionnaire), anxiety and depression (Goldberg Anxiety and Depression Scale questionnaire) and associated comorbidity were studied. Results: In the KDQOL scale, the most affected dimensions were: Work Status, Kidney Disease Burden, Sexual Function and Sleep. In the dimensions of the SF questionnaire, the most affected areas were: Physical Role, General Health and Physical Function. 42.6% of the patients presented probability of having anxiety, 52.5% depression, and 32.8% had the probability of suffering both alterations (anxiety and depression). Anxiety and depression were significantly associated with worse scores in all dimensions of the KDQOL-SF questionnaire. Conclusions: Hemodialysis patients have a worse quality of life than the healthy reference population, especially in the Kidney Disease Burden, Sleep, General health, Vitality, Physical Function and Physical Role dimensions. This decrease in the quality of life is related to the probability of suffering anxiety and/or depression. Female sex, associated comorbidity and length of time on hemodialysis are also associated with a worse quality of life

Improving enantiomeric resolutions by avoiding peak distortion effects in on-line coupled liquid chromatography to gas chromatography.

In this work, we study the effect of different variables affecting elution profile distortion on the enantiomeric resolution eventually achievable when working with on-line coupled liquid chromatography to gas chromatography (LC-GC). Specifically, the proposed configuration combines achiral reversed-phase liquid chromatography (RPLC) and chiral gas chromatography (enantio-GC), with heptakis-(2,3,6-tri-O-methyl)-ß-cyclodextrin as enantioselective stationary phase to analyse target fractions transferred (from LC to GC) via the through oven transfer adsorption desorption (TOTAD) interface. The high degree of orthogonality resulting from the combination of two chromatographic columns having very different separation mechanisms (and also requiring mobile phases in distinct physical states), as well as integration of the sample preparation step in the first dimension of the system, significantly contributed to exploit the performance of the proposed two-dimensional approach. Occasional adverse effects, which may result in severe peak distortions during LC-GC analysis and could be explained by flow instabilities due to viscous fingering, are circumvented by using the outstanding capacity of the TOTAD interface for achieving effective elimination of the eluent arriving from the LC preseparation.

Desarrollo de procedimientos de medida basados en la cromatografía líquida de alta resolución / Development of measurement procedures based on high-performance liquid chromatography

No disponible

Procedimiento para el estudio de interferencias exógenas en la medición de magnitudes biológicas. Documento técnico (2017) / Procedure for the study of exogenous interferences in the measurement of biological quantities. Technical document (2017)

No disponible

Validación de procedimientos de medida basados en la cromatografía líquida de alta resolución / Validation of measurement procedures based on high-performance liquid chromatography

No disponible

Procedimiento para la transferencia y revisión de intervalos de referencia biológicos / Procedure for transference and review of biological reference intervals

No disponible

Application of a diagnostic algorithm for the rare deficient variant Mmalton of alpha-1-antitrypsin deficiency: a new approach.

BACKGROUND AND OBJECTIVES: Alpha-1-antitrypsin deficiency (AATD) is associated with a high risk for the development of early-onset emphysema and liver disease. A large majority of subjects with severe AATD carry the ZZ genotype, which can be easily detected. Another rare pathologic variant, the Mmalton allele, causes a deficiency similar to that of the Z variant, but it is not easily recognizable and its detection seems to be underestimated. Therefore, we have included a rapid allele-specific genotyping assay for the detection of the Mmalton variant in the diagnostic algorithm of AATD used in our laboratory. The objective of this study was to test the usefulness of this new algorithm for Mmalton detection. MATERIALS AND METHODS: We performed a retrospective revision of all AATD determinations carried out in our laboratory over 2 years using the new diagnostic algorithm. Samples with a phenotype showing one or two M alleles and AAT levels discordant with that phenotype were analyzed using the Mmalton allele-specific genotyping assay. RESULTS: We detected 49 samples with discordant AAT levels; 44 had the MM and five the MS phenotype. In nine of these samples, a single rare Mmalton variant was detected. During the study period, two family screenings were performed and four additional Mmalton variants were identified. CONCLUSION: The incorporation of the Mmalton allele-specific genotyping assay in the diagnostic algorithm of AATD resulted in a faster and cheaper method to detect this allele and avoided a significant delay in diagnosis when a sequencing assay was required. This methodology can be adapted to other rare variants. Standardized algorithms are required to obtain conclusive data of the real incidence of rare AAT alleles in each region.

Made up by makeup--A case report about an exceptional kind of self-inflicted "injuries".

BACKGROUND: Self-inflicted injuries are a known, but challenging topic in the healthcare sector and the judicial system. Therefore, differentiation of these injuries from a third-party-interference is crucial in the field of forensic medicine. However, self-painted injuries with makeup, which entail misleading of medical staff and the administration of justice, have apparently not been described in the literature so far. CASE: A case of a rare kind of victim role staging in a 26-year-old Caucasian woman in the field of forensic medicine is presented. She supposedly had been robbed and harmed by two unknown men. The forensic examination revealed subjective symptoms and objective findings, such as skin discolorations appearing as fresh bruises. However, a closer look revealed makeup. After removal, no injuries were seen. CONCLUSIONS: Awareness of the existence of exceptional cases of victim role staging is essential in the daily routine of healthcare, judicial and forensic professionals. Therefore, a questioning attitude within the physical examination as well as proper assessment of objective findings is crucial. Furthermore, the importance of an interdisciplinary approach of possible factitious disorders is demonstrated. The sensitization may exclude a third-party-interference, prevent damages to the health care system, avoid misleading of the administration of justice, and, therefore, reduce socioeconomic costs. Moreover, the recognition may enable adequate interventions and provide patients with professional help.

Simultaneous occurrence of covert infections with small RNA viruses in the lepidopteran Spodoptera exigua.

Viral covert infections in invertebrates have been traditionally attributed to sublethal infections that were not able to establish an acute infection. Recent studies are revealing that, although true for some viruses, other viruses may follow the strategy of establishing covert or persistent infections without producing the death of the host. Recently, and due to the revolution in the sequencing technologies, a large number of viruses causing covert infections in all type of hosts have been identified. The beet armyworm, Spodoptera exigua (Lepidoptera: Noctuidae) is a worldwide pest that causes significant losses to agricultural and ornamental plant industries. In a previous project we used NGS to obtain a comprehensive transcriptome of the larval stage, revealing the presence of an important number of unigenes belonging to novel RNA viruses, most of them from the order Picornavirales. In order to characterize S. exigua viral complex, in this work we have completed the genomic sequences of two picorna-like viruses, and compared them to a SeIV1, a member of Iflaviridae previously described by our group. We performed additional studies to determine virus morphology, horizontal transmission, tissue and life stage distribution and abundance in the hosts. We discuss the role of virus persistent infections on insect populations.

ABCC transporters mediate insect resistance to multiple Bt toxins revealed by bulk segregant analysis.

BACKGROUND: Relatively recent evidence indicates that ABCC2 transporters play a main role in the mode of action of Bacillus thuringiensis (Bt) Cry1A-type proteins. Mapping of major Cry1A resistance genes has linked resistance to the ABCC2 locus in Heliothis virescens, Plutella xylostella, Trichoplusia ni and Bombyx mori, and mutations in this gene have been found in three of these Bt-resistant strains. RESULTS: We have used a colony of Spodoptera exigua (Xen-R) highly resistant to a Bt commercial bioinsecticide to identify regions in the S. exigua genome containing loci for major resistance genes by using bulk segregant analysis (BSA). Results reveal a region containing three genes from the ABCC family (ABBC1, ABBC2 and ABBC3) and a mutation in one of them (ABBC2) as responsible for the resistance of S. exigua to the Bt commercial product and to its key Spodoptera-active ingredients, Cry1Ca. In contrast to all previously described mutations in ABCC2 genes that directly or indirectly affect the extracellular domains of the membrane protein, the ABCC2 mutation found in S. exigua affects an intracellular domain involved in ATP binding. Functional analyses of ABBC2 and ABBC3 support the role of both proteins in the mode of action of Bt toxins in S. exigua. Partial silencing of these genes with dsRNA decreased the susceptibility of wild type larvae to both Cry1Ac and Cry1Ca. In addition, reduction of ABBC2 and ABBC3 expression negatively affected some fitness components and induced up-regulation of arylphorin and repat5, genes that respond to Bt intoxication and that are found constitutively up-regulated in the Xen-R strain. CONCLUSIONS: The current results show the involvement of different members of the ABCC family in the mode of action of B. thuringiensis proteins and expand the role of the ABCC2 transporter in B. thuringiensis resistance beyond the Cry1A family of proteins to include Cry1Ca.

CT-guided, minimally invasive, postmortem needle biopsy using the B-Rob II needle-positioning robot.

CT-guided, minimally invasive needle biopsy techniques can be used to retrieve tissue or body fluid samples for histologic tissue diagnoses in forensic investigations. The purpose of this study was an evaluation of CT-guided needle-positioning robot B-Rob II. To operate under CT guidance, we adopted the B-Rob II robotic needle placement system and its workflow. The accuracy and speed of the procedure were tested on a gelatin phantom in a series of 21 biopsies. We achieved an average needle placement accuracy of 1.8 mm (±1.1 mm) using robotic assistance. The procedure required an average of 2 min 21 s. The needle placement accuracy for minimally invasive needle biopsies using the B-Rob II biopsy robot is sufficiently accurate and fast for forensic postmortem examinations of focal organ changes. Further tests will be performed to test the feasibility of the robot for performing biopsies of focal organ changes in human bodies.

Direct enantiomeric analysis of Mentha essential oils.

A rapid and fully automated screening of chiral compounds in essential oils, aimed to the selection of natural sources of pure enantiomers of limonene and carvone, is performed by using on-line coupled reversed phase liquid chromatography with gas chromatography and mass spectrometry (RPLC-GC-MS). Essential oils obtained from Mentha spicata and Mentha piperita were analysed by direct injection into RPLC. The reported procedure includes fractionation and clean-up in RPLC, selection of the fraction to be transferred from RPLC to GC, trapping and concentration of the target compounds in the interface, thermal desorption and, finally, enantiomeric resolution and identification of chiral compounds by GC-MS. The presence of (S)-limonene and (R)-carvone as the unique enantiomeric forms existing for both compounds could be unambiguously established by transferring different volume fractions from RPLC to GC. Data obtained demonstrate high separation efficiency and well tunable selectivity in the on-line coupled RPLC-GC-MS analysis of chiral compounds.