Development and validation of an HPLC-MS/MS method for the simultaneous analysis of volatile organic compound metabolites, hydroxylated polycyclic aromatic hydrocarbons, and 8-hydroxy-2'-deoxyguanosine in human urine

Humans are widely and concurrently exposed to volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs). However, few studies have reported the internal co-exposure levels of these chemicals in occupational and general populations. Specifically, the associations revealed between the urinary levels of metabolites of VOCs (mVOCs), hydroxylated PAHs (OH-PAHs), and oxidative stress biomarkers for humans remain limited. In this study, a method based on solid-phase extraction (SPE) and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous analysis of 22 mVOCs, 12 OH-PAHs, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in human urine samples. The method was validated with all target analyte accuracies and precisions in the range of 76 %-120 % and 1 %-14 % at three levels of spiked urine samples, respectively. The limit of detection (LOD) and limit of quantification (LOQ) of the target analytes were 0.01-0.34 ng/mL and 0.01-7.57 ng/mL, respectively. And the method was applied to measure urinary levels of target analytes from 38 petrochemical workers in Guangzhou, South China. Except for 3-hydroxy-benzo[a]pyrene, all target analytes were detected in the urine samples. The average levels were 0.05-12.6 ng/mL for individual OH-PAHs, 0.20-73620 ng/mL for individual mVOCs, and 1.00 ng/mL for 8-OHdG. Additionally, 3-hydroxy-phenanthrene, 1-hydroxy-pyrene, 6-hydroxy-chrysene, N-acetyl-S-(trichlorovinyl)-L-cysteine, 2-methylhippuric acid, thiodiacetic acid, trans, trans-Muconic acid, and N-acetyl-S-(3,4-dihydroxybutyl)-L-cysteine had statistically significant positive effects on 8-OHdG levels, while 1-hydroxy-naphthalene, 1,2-dihydroxybenzene, and hippuric acid showed a negative effect on 8-OHdG, indicating these metabolites could lead to synergistic or antagonistic oxidative DNA damage. This study provides a robust analytical method that permits a comprehensive assessment of co-exposure to PAHs and VOCs and their potential adverse health effects.

Guidelines for management of pediatric acute hyperextension spinal cord injury

Pediatric acute hyperextension spinal cord injury (SCI) named as PAHSCI by us, is a special type of thoracolumbar SCI without radiographic abnormality and highly related to back-bend in dance training, which has been increasingly reported. At present, it has become the leading cause of SCI in children, and brings a heavy social and economic burden. Both domestic and foreign academic institutions and dance education organizations lack a correct understanding of PAHSCI and relevant standards, specifications or guidelines. In order to provide standardized guidance, the expert team formulated this guideline based on the principles of science and practicability, starting from the diagnosis, differential diagnosis, etiology, admission evaluation, treatment, complications and prevention. This guideline puts forward 23 recommendations for 14 related issues.

The routine cutoff displacement of 2 mm may not reliably reflect the stability of paediatric lateral humeral condyle fractures

INTRODUCTION

Lateral humeral condyle fracture is one of the most common fractures in children. However, the prediction of the stability of the fracture with a cutoff displacement of 2 mm remains controversial. The aim of this study was to evaluate the reliability of the routine cutoff displacement of 2 mm in predicting the stability of paediatric lateral humeral condyle fractures.

METHODS

A cohort of 79 children with imaging results for lateral humeral condyle fractures from 2013 to 2019 was evaluated. The displacement on the radiographs was measured by three surgeons at different levels, and ultrasound images were obtained by two senior surgeons. The interobserver and intraobserver reliability was assessed by the intraclass correlation coefficient (ICC). A binary logistic regression model and receiver operating characteristic (ROC) curves were used to evaluate the association between the measurement and the integrity of cartilage hinges.

RESULTS

The ICC for the interobserver reliability was 0.85, and the intraobserver reliability was 0.93. For each additional millimetre of displacement, the odds of cartilage hinge disruption increased by 70%. The ROC curve determined that the Youden index was only 0.07 (sensitivity, 97.8%; specificity, 8.8%) with a cutoff displacement of 2 mm.

CONCLUSIONS

The routine cutoff displacement of 2 mm may not reliably reflect the stability of paediatric lateral humeral condyle fractures. The cutoff value is sensitive but not specific for predicting whether the cartilage hinge is intact.

A novel transverse ultrasonography technique for minimally displaced lateral humeral condyle fractures in children

INTRODUCTION

Management of minimally displaced lateral humeral condyle fractures in pediatric patients is controversial. This is primarily because with current imaging modalities it is difficult to accurately and conveniently determine the stability of the fractures by detecting the integrity of the cartilage hinge. Nevertheless, transverse ultrasonography has not been intensively reported in previous studies.

HYPOTHESIS

Transverse ultrasonography can determine the integrity of the cartilage hinge in minimally displaced lateral condyle fractures.

MATERIALS AND METHODS

We retrospectively reviewed the medical records of 39 pediatric patients with minimally displaced fractures of the lateral humeral condyle who underwent transverse ultrasonography between 2014 and 2017. Conservative treatment was given to pediatric patients with intact cartilage hinges that had been confirmed by transverse ultrasound images. Surgical treatment was recommended for pediatric patients with disrupted cartilage hinges. Data regarding healing of the lateral humeral condyle fractures were recorded and analyzed.

RESULTS

According to transverse ultrasonography, there were 14 children with intact cartilage hinges and 25 children with disrupted cartilage hinges. Fourteen children with intact cartilage hinges of the fracture were treated conservatively, and none of them showed secondary displacement. There were 16 children in whom there was surgical intervention, and 9 other children decided to have conservative treatment among the 25 children with disruption of the cartilage hinge. Five of these 9 children who underwent conservative treatment were found to have further displacement during an average of 12.6 days after the fracture event, and no other patient was found to have further displacement.

CONCLUSION

Transverse ultrasonography can simply and accurately determine the stability of minimally displaced lateral condyle fractures without sedation, ionizing radiation or invasive techniques. We recommend routine use of transverse ultrasonography to detect stability of the fractures, which can effectively avoid inadequate treatment and unnecessary surgery in pediatric patients with minimally displaced fractures of the lateral humeral condyle.

LEVEL OF EVIDENCE

IV, retrospective cohort study.

Radiographic outcome of children older than twenty-four months with developmental dysplasia of the hip treated by closed reduction and spica cast immobilization in human position: a review of fifty-one hips

PURPOSE

This study aimed to investigate the radiographic outcomes, rate of redislocation, and avascular necrosis of proximal femoral epiphysis (AVN) in patients aged 24 to 36 months with developmental dysplasia of the hip (DDH) treated by closed reduction (CR) and spica cast immobilization in human position.

MATERIAL AND METHODS

We reviewed the medical records of 39 patients (51 hips) aged 24 to 36 months with DDH treated by CR and spica cast immobilization in human position. The Tönnis grade, rate of redislocation and AVN, acetabular index (AI), centre-edge angle (CEA), and Severin radiographic grade were evaluated on plain radiographs.

RESULTS

Among the included 39 patients (51 hips), 15 hips (29.4%) were Tönnis grade II, 24 hips (47.1%) were grade III, and 12 hips (23.5%) were grade IV. In 47 hips (92.2%), the ossific nucleus was present at the time of CR. Stable reduction was achieved by CR in 39/51 hips (76.5%) and redislocation occurred in 12/51 hips (23.5%). Among the 12 hips that redislocated, 11 underwent open reduction and one repeated CR. Two out of 40 hips (5%) treated by CR developed AVN. Overall, 54.6% of the hips had satisfactory outcomes (39.2% Severin type I and 17.6% type II), while 45.4% had unsatisfactory outcomes (39.2% Severin type III and 3.9% type IV). Of the 40 hips treated by CR, 57.5% and 42.5% of cases had satisfactory outcomes and residual acetabular dysplasia, respectively. Six out of 11 hips (54.6%) treated by open reduction and pelvic osteotomy had satisfactory outcomes.

CONCLUSIONS

Our study showed that stable CR could be achieved in 76.5% of patients aged 24 to 36 months with DDH at the time of index procedure. Satisfactory outcomes can be expected in 56.4% of the cases (5.0% AVN rate), although late acetabular dysplasia may develop in 43.6% of the hips.

[Clinical analysis of preimplantation genetic diagnosis with HLA matching for beta-thalassemia]

OBJECTIVE

To investigate the efficacy and feasibility of preimplantation genetic diagnosis(PGD)with human leukocyte antigen(HLA)matching for beta-thalassemia.

METHODS

A total of 43 referred beta-thalassemia couples, with at least on child in need of hematopoietic stem cell transplantation(HSCT), underwent PGD for HLA matching at the First Affiliated Hospital of Sun Yat-sen University from 2010 to 2015. PGD cycles of these couples were retrospectively analyzed, and 15 infants born from PGD-HLA were followed up.

RESULTS

A total of 84 oocyte retrieval cycles were performed, providing 14±7 oocytes per cycle. Fifty nine embryos biopsied cycles were done, including 24 cleavage stage and 35 blastocyst stage biopsy cycles. In cleavage stage, 259 embryos were biopsied, 93.4%(242/259)of them with conclusive molecular diagnosis, and the percentage of unaffected embryos(normo-homozygote and heterozygote)was 71.4%(185/259). The percentage of HLA matched unaffected embryos was 9.3%(24/259). In blastocyst stage, 306 embryos were biopsied, while 93.8%(287/306)of them were conclusive, and the percentage of unaffected embryos was 70.6%(216/306). The percentage of HLA matched unaffected embryos in blastocyst stage biopsy was 14.4%(44/306), which was higher than in cleavage stage biopsy(P< 0.05). Forty three female carriers underwent 48 embryo transfer cycles including 3 fresh and 45 frozen-thawed embryo transfer cycles. Three fresh embryo transfer cycles were done after cleavage stage biopsy, resulted in a birth of healthy twins born at 36 weeks' gestation. All the embryos were frozen after blastocyst biopsied. Totally, 54 frozen-thawed embryos that were transferred in 45 frozen-thawed embryo transfer cycles included 25 embryo from cleavage stage biopsy and 29 embryo from blastocyst stage biopsy, and 42 of them were HLA matched. Clinical pregnancy rate and implantation rate per cycle in frozen-thawed embryo transfer were 38%(17/45)and 37%(20/54)respectively. A total of 15 infants were born, 2 were from a fresh embryo transfer cycle, and 13 were from frozen-thawed embryo transfer cycles. RESULTS of prenatal diagnosis from delivered cases were matched to that of PGD. Four sick children have been cured by HSCT from these HLA matched born siblings.

CONCLUSION

PGD with HLA matching is an established method for conceiving a child who may donate hematopoietic stem cells to save an ill sibling.

Roles of the polypyrimidine tract and 3' noncoding region of hepatitis C virus RNA in the internal ribosome entry site-mediated translation

Hepatitis C virus (HCV) genome contains a 3'noncoding region (3'NCR) consisting of a variable region, a polypyrimidine tract (polyU/UC) and the X region. To examine the roles of 3'NCR and polyU/UC tract in the internal ribosome entry site (IRES)-mediated translation process, a variety of 3'NCRs containing different lengths of polyU/UC tract were obtained from HCV infected patients and cloned respectively to the downstream of the firefly luciferase coding gene linked to HCV 5'NCR and 30 nucleotides of core gene (containing IRES element). The results of in vitro translation in rabbit reticulocyte lysate (RRL) and cell transfection assay in mammalian cells showed that the IRES-mediated translation efficiency could be enhanced by the full-length of 3'NCR of HCV RNA. However, contradictory results were observed when the role of polyU/UC tract in the IRES-mediated translation was studied. While the IRES-mediated translation efficiency was inhibited by the presence of polyU/UC tract in in vitro translation experiments, transfection of these expression cassettes into hepatic cell line showed that polyU/UC tract enhanced IRES-mediated translation efficiency in vivo. Cellular-fraction complement experiments showed that cellular factors were required for the enhancement by the polyU/UC tract. Further antibody blocking assay and UV cross-linking assay suggested the correlation of IRES-mediated translation with host factors, including the La protein. The data above also indicated that the modulations of the IRES-mediated translation by the HCV 3'NCR and the polyU/UC tract were in a length-independent manner.

Mechanisms underlying the antiarrhythmic and arrhythmogenic actions of quinidine in a Purkinje fiber-ischemic gap preparation of reflected reentry

The effects of therapeutic levels of quinidine were studied in an ischemic gap preparation of reflected reentry. The preparation consisted of a Purkinje fiber mounted in a three-compartment chamber. A narrow central compartment was perfused with a solution prepared to mimic the extracellular milieu at a site of ischemia. Quinidine in concentrations that exert little effect on normal Purkinje tissue, 1 to 2 micrograms/ml, greatly impaired conduction and markedly prolonged refractoriness across the ischemic gap. The drug effected these changes by (1) extending the inexcitable zone within the depressed region, (2) decreasing the amplitude of the input signal entering this zone, and (3) decreasing the excitability of the tissue beyond the depressed zone (evaluated by current clamp techniques). These actions of the drug produced both antiarrhythmic and proarrhythmic effects. When the initial level of conduction impairment was high, quinidine totally suppressed reflected reentry at all frequencies by precipitating complete anterograde conduction block. At intermediate levels of block, the drug generally caused a prominent shift of the frequency dependence of reentrant activity to lower stimulation rates. Finally, when conduction was relatively less impaired, quinidine created the conditions for reflected reentry to occur. Our results suggest that the heart rate dependence of reentrant arrhythmias might be of prognostic value in the administration of antiarrhythmic drugs.