Nomogram for prediction of hepatocellular carcinoma recurrence after liver resection.

BACKGROUND: Hepatocellular carcinoma (HCC) is a common malignancy with high mortality. Liver resection (LR) is a curative treatment for early-stage HCC, but the prognosis of HCC patients after LR is unsatisfactory because of tumor recurrence. Prognostic prediction models with great performance are urgently needed. The present study aimed to establish a novel prognostic nomogram to predict tumor recurrence in HCC patients after LR. METHODS: We retrospectively analyzed 726 HCC patients who underwent LR between October 2011 and December 2016. Patients were randomly divided into the training cohort (n = 508) and the testing cohort (n = 218). The protein expression of 14 biomarkers in tumor tissues was assessed by immunohistochemistry. The nomogram predicting recurrence-free survival (RFS) was established by a multivariate Cox regression analysis model and was evaluated by calibration curves, Kaplan-Meier survival curves, time-dependent areas under the receiver operating characteristic (ROC) curves (AUCs), and decision curve analyses in both the training and testing cohorts. RESULTS: Alpha-fetoprotein [hazard ratio (HR) = 1.013, P = 0.002], portal vein tumor thrombosis (HR = 1.833, P < 0.001), ascites (HR = 2.024, P = 0.014), tumor diameter (HR = 1.075, P < 0.001), E-cadherin (HR = 0.859, P = 0.011), EMA (HR = 1.196, P = 0.022), and PCNA (HR = 1.174, P = 0.031) immunohistochemistry scores were found to be independent factors for RFS. The 1-year and 3-year AUCs of the nomogram for RFS were 0.813 and 0.739, respectively. The patients were divided into the high-risk group and the low-risk group by median value which was generated from the nomogram, and Kaplan-Meier analysis revealed that the high-risk group had a shorter RFS than the low-risk group in both the training (P < 0.001) and testing cohorts (P < 0.001). CONCLUSIONS: Our newly developed nomogram integrated clinicopathological data and key gene expression data, and was verified to have high accuracy in predicting the RFS of HCC patients after LR. This model could be used for early identification of patients at high-risk of postoperative recurrence.

Value of portal venous gas and a nomogram for predicting severe neonatal necrotizing enterocolitis.

BACKGROUND: Whether portal venous gas (PVG) is a sign of severe neonatal necrotizing enterocolitis (NEC) and predicts poor prognosis remains uncertain. METHODS: Patients from two centres were randomly assigned to a training set or a validation set. A nomogram model for predicting severe NEC was developed on the basis of the independent risk factors selected by least absolute shrinkage and selection operator (LASSO) regression analysis and multivariate logistic regression analysis. The model was evaluated based on the area under the curve (AUC), calibration curve, and decision curve analysis (DCA). RESULTS: A total of 585 patients met the study criteria, and propensity score matching resulted in 141 matched pairs for further analysis. Patients with PVG had a greater risk of surgical intervention or death compared with patients without PVG. A prediction model for severe NEC was established based on PVG, invasive mechanical ventilation (IMV), serum platelet count (PLT) and pH <7.35 at the onset of NEC. The model had a moderate predictive value with an AUC > 0.8. The calibration curve and DCA suggested that the nomogram model had good performance for clinical application. CONCLUSION: A prediction nomogram model based on PVG and other risk factors can help physicians identify severe NEC early and develop reasonable treatment plans. IMPACT: PVG is an important and common imaging manifestation of NEC. Controversy exists regarding whether PVG is an indication for surgical intervention and predicts poor prognosis. Our study suggested that patients with PVG had a greater risk of surgical intervention or death compared with patients without PVG. PVG, IMV, PLT and pH <7.35 at the onset of NEC are independent risk factors for severe NEC. A prediction nomogram model based on PVG and other risk factors may help physicians identify severe NEC early and develop reasonable treatment plans.

[Analysis of IVD gene variants in four children with isovalerate acidemia].

OBJECTIVE: To detect variants of IVD gene among 4 neonates with suspected isovalerate acidemia in order to provide a guidance for clinical treatment. METHODS: 111 986 newborns and 7461 hospitalized children with suspected metabolic disorders were screened for acyl carnitine by tandem mass spectrometry. Those showing a significant increase in serum isovaleryl carnitine (C5) were analyzed for urinary organic acid and variants of the IVD gene. RESULTS: Four cases of isovalerate acidemia were detected, which included 2 asymptomatic newborns (0.018‰, 2/111 986) and 2 children suspected for metabolic genetic diseases (0.268‰, 2/7461). The formers had no obvious clinical symptoms. Analysis of acyl carnitine has suggested a significant increase in C5, and urinary organic acid analysis has shown an increase in isovaleryl glycine and 3-hydroxyisovalerate. Laboratory tests of the two hospitalized children revealed high blood ammonia, hyperglycemia, decreased red blood cells, white blood cells, platelets and metabolic acidosis. The main clinical manifestations have included sweaty foot-like odor, feeding difficulty, confusion, drowsiness, and coma. Eight variants (5 types) were detected, which included c.158G>A (p.Arg53His), c.214G>A (p.Asp72Asn), c.548C>T (p.Ala183Val), c.757A>G (p.Thr253Ala) and 1208A>G (p.Tyr403Cys). Among these, c.548C>T and c.757A>G were unreported previously. None of the variants was detected by next generation sequencing of 2095 healthy newborns, and all variants were predicted to be likely pathogenic based on the guidelines from the American College of Medical Genetics and Genomics. CONCLUSION: The incidence of isovalerate acidemia in Liuzhou area is quite high. Screening of metabolic genetic diseases is therefore recommended for newborns with abnormal metabolism. The discovery of novel variants has enriched the mutational spectrum of the IVD gene.

Decreased plasma levels of PDGF-BB, VEGF-A, and HIF-2α in preterm infants after ibuprofen treatment.

Introduction: Ibuprofen is one of the most common non-steroidal anti-inflammatory drugs used to close patent ductus arteriosus (PDA) in preterm infants. PDA is associated with bronchopulmonary dysplasia (BPD), while PDA closure by ibuprofen did not reduce the incidence of BPD or death. Previous studies have indicated an anti-angiogenesis effect of ibuprofen. This study investigated the change of angiogenic factors after ibuprofen treatment in preterm infants. Methods: Preterm infants with hemodynamically significant PDA (hsPDA) were included. After confirmed hsPDA by color doppler ultrasonography within 1 week after birth, infants received oral ibuprofen for three continuous days. Paired plasma before and after the ibuprofen treatment was collected and measured by ELISA to determine the concentrations of platelet-derived growth factor-BB (PDGF-BB) and vascular endothelial growth factor A (VEGF-A), and hypoxia-inducible factor-2α (HIF-2α). Results: 17 paired plasma from infants with hsPDA were collected. The concentration of PDGF-BB and VEGF-A significantly decreased after ibuprofen treatment (1,908 vs. 442 pg/mL for PDGF-BB, 379 vs. 174 pg/mL for VEGF-A). HIF-2α level showed a tendency to decrease after ibuprofen treatment, although the reduction was not statistically significant (p = 0.077). Conclusion: This study demonstrated decreased vascular growth factors after ibuprofen exposure in hsPDA infants.

Histopathological Diagnosis System for Gastritis Using Deep Learning Algorithm / 中国医学科学杂志(英文版)

Objective To develope a deep learning algorithm for pathological classification of chronic gastritis and assess its performance using whole-slide images (WSIs). Methods We retrospectively collected 1,250 gastric biopsy specimens (1,128 gastritis, 122 normal mucosa) from PLA General Hospital. The deep learning algorithm based on DeepLab v3 (ResNet-50) architecture was trained and validated using 1,008 WSIs and 100 WSIs, respectively. The diagnostic performance of the algorithm was tested on an independent test set of 142 WSIs, with the pathologists' consensus diagnosis as the gold standard. Results The receiver operating characteristic (ROC) curves were generated for chronic superficial gastritis (CSuG), chronic active gastritis (CAcG), and chronic atrophic gastritis (CAtG) in the test set, respectively.The areas under the ROC curves (AUCs) of the algorithm for CSuG, CAcG, and CAtG were 0.882, 0.905 and 0.910, respectively. The sensitivity and specificity of the deep learning algorithm for the classification of CSuG, CAcG, and CAtG were 0.790 and 1.000 (accuracy 0.880), 0.985 and 0.829 (accuracy 0.901), 0.952 and 0.992 (accuracy 0.986), respectively. The overall predicted accuracy for three different types of gastritis was 0.867. By flagging the suspicious regions identified by the algorithm in WSI, a more transparent and interpretable diagnosis can be generated. Conclusion The deep learning algorithm achieved high accuracy for chronic gastritis classification using WSIs. By pre-highlighting the different gastritis regions, it might be used as an auxiliary diagnostic tool to improve the work efficiency of pathologists.

Role of primary cilia in common skin tumors / 中华皮肤科杂志

Primary cilium has attracted increasing attention in the biomedical field in recent years.It exists in the surface of various cells and is micro-sized,but its complex structures have not been clear.The primary cilium has an important role in sensory perception.Cells can receive extracellular mechanical and chemical signals through primary cilia,and primary cilia can assist in transferring signals into cells,followed by cellular responses.Recent studies have shown that the primary cilium also plays an important role in embryonic development and malignant transformation of cells.The investigation into primary cilia will facilitate the understanding of malignant transformation of cells and development of tumors.According to the related literature in recent years,this review summarizes the relationship between the primary cilium and common skin tumors,as well as potential targets for these tumors,so as to provide references and new sights for further researches.

Epidemiology of birth defects based on surveillance data from 2011-2015 in Guangxi, China: comparison across five major ethnic groups.

BACKGROUND: The causes of birth defects (BDs) are complex and include genetic and environmental factors and/or their interactions. More research is needed to describe the epidemiology of BDs within specific regions of China. This study focused on differences in the prevalence of BDs based on ethnicity in a large city in Guangxi Province, China. METHODS: Surveillance data of infants born in 114 registered hospitals in Liuzhou between 2011 and 2015 were analyzed to determine the epidemiology of BDs across five major ethnic groups. We calculated the prevalence of BDs and relative risk of BDs by ethnicity. RESULTS: There were 260,722 perinatal infants of which 6581 had BDs, with the average prevalence of 25.24 per 1000 perinatal infants (PIs). Prevalence data showed an obvious uptrend over the past 5 years. Han had the highest prevalence of total BDs (28.98‰), followed by Zhuang (25.19‰), Yao (18.50‰), Miao (15.78‰) and Dong (14.24‰). Relative to the Han; Zhuang, Miao, Yao, and Dong had a lower risk of musculoskeletal and urogenital malformations; Miao and Yao had a lower risk of cardiovascular malformation; and Dong had a lower risk of cardiovascular and craniofacial malformation. Several maternal risk factors were found to be associated with BDs (e.g., maternal and gestational age, number of antenatal care visits). CONCLUSION: This study provided a comprehensive description of ethnic differences in the risk of BDs in Liuzhou City, China. Observed ethnic differences in the risk of BDs may be related to genetic susceptibilities, environment, cultural customs, or to potential combinations of these factors.

Epidemiology of Candida albicans and non-C.albicans of neonatal candidemia at a tertiary care hospital in western China.

BACKGROUND: Although the majority of Candida infections occur in the developing world, candidemia epidemiology is poorly understood in these countries. The aim of this study was to investigate the epidemiology of non-Candida albicans (non-C. albicans) candidemia among neonates at Liuzhou Maternity and Child Healthcare Hospital in China. METHODS: A retrospective review of all positive blood culture about Candida species in neonatal intensive care unit was conducted between January 2012 and November 2015. Information about demographics, risk factors and outcome of candidemia were collected. Univariate and multivariate logistic regression models were used to identify the risk factors associated with the development of non-C.albicans candidemia. RESULTS: The prevalence of candidemia in infants was 1.4%. Non-C.albicans was responsible for 56.5% of neonatal candidemia. The predisposing factors for development of non-C.albicans candidemia among infants included mechanical ventilation [odds ratio (OR), 95% confidence interval (95%CI) = 3.13, 1.07-9.14; P = 0.037] and use of assisted reproductive technology (OR, 95%CI = 4.52, 1.39-14.77; P = 0.012). The overall mortality rate of candidemia was 8.7% and non-C.albicans attributed to 83.3% of all mortalities. CONCLUSIONS: Non-C.albicans species are the major cause of candidemia in local neonatal group. The study highlights the urgent needs to evaluate the possibility of development of non-C.albicans candidemia in neonates exposed to these risk factors and much emphasis must be laid on the early implementation of medical intervention to reduce the incidences of candidemia in neonates.

Epidemiology of and risk factors for neonatal candidemia at a tertiary care hospital in western China.

BACKGROUND: The prevalence and clinical characteristics of neonatal candidemia are poorly understood in western China. The aim of our study was to evaluate the epidemiological features of neonatal candidemia in the Liuzhou Maternity and Child Healthcare Hospital. METHODS: A retrospective case-control study was conducted between January 2012 and November 2015. Electronic databases were reviewed and data on Candida species were isolated from blood cultures and candidemia incidence, risk factors, and mortality were extracted. Univariate and multivariate logistic regression analysis were performed to identify risk factors associated with candidemia. RESULTS: During the 4-year period, candidemia was identified in 69 newborns, for an incidence rate of 13.6 per 1000 admissions. Prolonged antibiotic therapy duration [odds ratio (OR), 95% confidence incidence (95% CI) = 1.06, 1.01-1.10], total parenteral nutrition [OR, 95% CI = 6.03, 2.10-17.30] and neurodevelopmental impairment (OR, 95% CI = 7.34, 1.18-45.80) were all associated with increased odds of candidemia development in infants (P value was 0.010, 0.001, 0.033, respectively). The overall mortality rate was 7.2% in the candidemia group. CONCLUSIONS: Prolonged duration of antibiotic therapy, presence of total parenteral nutrition and neurodevelopmental impairment were the major risk factors associated with neonatal candidemia. This study highlights the importance of the early detection, diagnosis and treatment of neonatal candidemia.

Risk factors and clinical analysis of candidemia in very-low-birth-weight neonates.

BACKGROUND: Candidemia is the third leading cause of morbidity and mortality in preterm or very-low-birth-weight infants. The incidence and risk factors of candidemia in this population are poorly known in western China. METHODS: A case-control retrospective study of candidemia was conducted from January 2012-November 2015 in the Liuzhou Maternity and Child Healthcare Hospital. Data were analyzed by univariate analysis and multivariate logistic regression. RESULTS: Forty-eight confirmed cases of candidemia were identified during the study period, indicating an incidence of 106.9 per 1,000 admissions of very-low-birth-weight infants. Candida albicans was the most common pathogen and was isolated in 39.6% of infants with candidemia. The mortality rate of the case group was 10.4% versus 2.1% in the control group (P = .128). The multivariable logistic regression model identified that carbapenem use (odds ratio [OR], 11.39; 95% confidence interval [CI], 3.28-39.54), total parenteral nutrition (OR, 10.16; 95% CI, 2.25-45.94), and prolonged hospitalization (OR, 1.04; 95% CI, 1.01-1.07) were all associated with the risk of developing neonatal candidemia. CONCLUSION: Very-low-birth-weight infants are at a significantly high risk of developing candidemia. The local neonatal intensive care unit management teams should effectively focus on decreasing the overall use of carbapenems, improving catheter care, removing catheters early, and shortening hospitalizations to reduce the incidence of candidemia.

[The molecular mechanism of necroptosis].

Programmed necrosis called necroptosis, is different from traditional necrosis and apoptosis, it has attracted considerable attention over the last few years. Necroptosis can be initiated through many factors such as tumor necrosis factor receptor (TNFR) or pattern recognition receptor (PRR), and receptor-interacting protein (RIP) 1 and 3 are two key proteins during the process. A lot of molecules have been characterized as modulators and effectors of necroptosis, including poly(ADP-ribose) polymerase (PARP-1), reactive oxygen species (ROS), Ca(2+), which can destruct mitochondria or other organelles and induce cell dead through caspase-independent pathway. Then, damage-associated molecular pattern (DAMP) molecules were released from necroptosis cells, recognized and internalized by phagocytes. Here, we briefly discuss the initiation and execution of necroptosis and the clearance of death cells.

Recipient IL-6-572C/G genotype is associated with reduced incidence of acute rejection following liver transplantation.

OBJECTIVE: Acute rejection resulting from alloimmune responses is a major risk factor affecting patient survival following liver transplantation. Since interleukin (IL)-6 can mediate acute rejection, the association between IL-6 gene single nucleotide polymorphisms (SNPs) and incidence of acute rejection in liver transplant recipients was investigated. METHODS: Patients who received liver transplant between January 2005 and December 2010 were typed for IL6-572C/G (rs1800796) polymorphisms using the snapshot technique. Association between genotype and acute rejection was analysed using the SNP Statistics website: http://bioinfo.iconcologia.net/snpstats/start.htm. Allelic and genotypic distributions for rs1800796 were compared among 335 patients with or without acute rejection within the first 6 months following liver transplant. RESULTS: Incidence of acute rejection was 11.94%. A heterozygous CG genotype for IL6-572C/G was associated with a lower acute rejection rate compared with homozygous CC or GG genotypes. CONCLUSION: IL6-572 CG genotype may be related to protection from acute rejection following liver transplant in Han Chinese patients.

Lack of association between genetic polymorphisms in cytokine genes and tumor recurrence in patients with hepatocellular carcinoma undergoing transplantation.

BACKGROUND: Recurrence of hepatocellular carcinoma (HCC) after liver transplantation (LT) remains one of the most common causes of poor long-term survival. However, the host genetic factors affecting increased risk of tumor recurrence after transplantation have not been thoroughly elucidated. The present study was designed to investigate the association of cytokine gene polymorphisms with the risk of tumor recurrence in LT patients for HCC. METHODS: Eleven single-nucleotide polymorphisms within the promoter regions of 7 cytokine genes, i.e., the IL-1 family (IL-1alpha and IL-1beta), IL-6, IL-8, IL-10, TNF-alpha, and TGF-beta1, were genotyped in 93 HCC patients treated with LT using DNA sequencing. The association between these polymorphisms and the risk of tumor recurrence was evaluated while controlling confounding clinical variables. RESULTS: The genotype frequency of IL-10 -1082 A/G in patients with and without recurrence of HCC was AA 83.3%, GA 16.7% and AA 97.6%, GA 2.4%, respectively. The association between IL-10 -1082 GA and recurrence was significant (P=0.033). No other single-nucleotide polymorphism in the cytokine gene was found to be associated with recurrence. Kaplan-Meier survival curves showed that the homozygous AA patients had a significantly longer mean recurrence-free survival than heterozygous GA patients (23.5 vs 5.7 months, P=0.001). However, multivariate analysis failed to reveal that the GA genotype of IL-10 -1082 A/G was an independent indicator of recurrence. CONCLUSIONS: This study suggests the lack of association of selected cytokine gene polymorphisms with HCC recurrence after LT in the Han Chinese population. The finding does not exclude the idea that other cytokine polymorphisms could act as candidate biomarkers of disease prognosis.

[Studying the damages of mouse retina induced by 2,5-hexanedione].

OBJECTIVE: To study toxic effects of 2,5-hexanedione (2,5-HD) on pathology and lipid peroxidation in mouse retina. METHODS: Forty-eight mice were randomly divided into blank control group (12 mice), negative control group exposed to normal solution (12 mice) and group exposed to 2,5-HD for 2. 4 and 8 weeks, respectively (24 mice) by intraperitoneal injection (2.5% 2,5-HD) at the dose of 400 mg/kg. The pathological changes of mouse retina were examined under light microscope. The activity of superoxide dismutase (SOD) and the level of malondialdehyde (MDA) in mouse retina were detected. RESULTS: The retinal structure in the blank and negative control groups was normal. In mice exposed to 2,5-HD for 8 weeks, the swelling of outer and inner segments and disorder arrangement of the segments without clear boundary were found. The staining of outer plexiform layers was uneven and the irregular loose structure appeared. The hyperchromatic pyknotic and necrosis nuclei were presented in ganglion cells layer. Compared with the control and blank groups, the activities of SOD gradually and significantly reduced and the concentrations of MDA increased in group exposed to 2,5-HD (P < 0.05). CONCLUSION: 2,5-HD can induce the injury of retina tissues of mice, which may be associated with the lipid peroxidation.

Aberrant methylation of the CADM1 promoter is associated with poor prognosis in hepatocellular carcinoma treated with liver transplantation.

Approximately 20-40% of hepatocellular carcinoma (HCC) patients who undergo liver transplantation (LT) experience HCC recurrence within 5 years of the operation. Current predictors cannot sufficiently differentiate patients at risk for biochemical recurrence. The aim of the present study was to investigate the methylation status and expression levels of cell adhesion molecule 1 (CADM1) in HCC; to elucidate its regulation mechanisms; and finally, to evaluate the potential predictive value for tumor recurrence. Aberrant hypermethylation of CADM1 was frequently found in HCC cell lines with decreased CADM1 mRNA by bisulfite sequencing PCR. Re-expression of CADM1 was induced by treatment with demethylating agents. The promoter region of CADM1 was identified and the basal promoter activity was located in the -226 to -146 region relative to the transcriptional start site (TSS). Site-directed mutagenesis revealed that the consensus Sp1 binding site located in the basal promoter region was important for mediating CADM1 promoter activity. Furthermore, aberrant hypermethylation of CADM1 was detected in 34 of 82 (41.5%) of HCC tissues. The recurrence rate of the patients with CADM1 methylation was higher compared to that without CADM1 methylation (70.6% versus 33.3%; P=0.001). Multivariate analysis revealed that CADM1 methylation status (HR = 2.788; 95% CI, 1.043-5.063; P=0.010) was an independent prognostic factor for disease-free survival (DFS) of HCC patients treated with LT. In conclusion, CADM1 methylation may be used as a potential predictive biomarker for tumor recurrence of HCC after LT.

[NP9 gene inhibits tumorigenicity of nasopharyngeal carcinoma].

OBJECTIVE: To study the effect of NP9 on the growth of transplanted nasopharyngeal carcinoma (NPC) in nude mice and explore the mechanisms involved. METHODS: Recombinant pRc/CMV2-NP9 plasmid was constructed and transfected into the NPC cell lines by lipofectamine 2000. Cell clones stably expressing NP9 were obtained by detecting the mRNA expression of NP9 in G418-resistant clones with RT-PCR. The tumorigenicity and size of transplanted tumors were assessed after inoculation of NPC cells and their transgene clones into Balb/C mice. The expression of PCNA and cyclin D1 in transplanted tumors was detected by immunohistochemistry. RESULTS: The expression of NP9 was detected in some of NP9 gene-transfected G418-resistant clones of CNE1 and SUNE1. In vivo experiments showed that the tumorigenicity of CNE19 clone was decreased significantly compared to that of CNE1 and its vector control, and the transplanted tumors grew more slowly from SUNE1/NP9 than from SUNE1 and SUNE1/vector. Compared with the vector control, the expression of cyclin D1 and PCNA in CNE1/NP9 transplants was decreased. CONCLUSION: NP9 inhibits tumorigenicity and growth of NPC transplanted tumor by down-regulating the expression of cyclin D1 and PCNA.

[A study on lymphocyte DNA damage in traffic policemen in Guangzhou].

OBJECTIVE: To study the effect of occupational exposure to traffic exhaust and smoking on DNA damage in traffic policemen. METHODS: 812 traffic policemen (741 men and 71 women, 130 of office-work and 682 of outside work) from 8 districts in Guangzhou were investigated. Blood samples were taken by venipuncture and lymphocytes were collected by using lymphocyte separation medium and centrifugation. The comet assay was used to measure DNA damage. RESULTS: The office-work policemen [(37.7 +/- 9.5) years] were older than the outside-work ones [(32.3 +/- 8.1) years, P < 0.001]. No significant difference was observed in sex (P = 0.08) and age (P = 0.45). Comet assay showed that occupational exposure to traffic exhaust significantly increased tail length [4.20 micro m, 95% CI: (3.98 - 4.42) micro m vs 3.23 micro m, 95% CI: (2.82 - 3.7) micro m, P < 0.001]. Smokers had longer tail length [4.66 micro m, 95% CI: (4.37 - 4.97) micro m] than ex-smokers [3.28 micro m, 95% CI: (2.57 - 4.17) micro m] and nonsmokers [3.47 micro m, 95% CI: (3.21 - 3.75) micro m, P < 0.001]. In nonsmokers, significant increase in tail length was observed by passive smoking at home (P = 0.004) but not at work (P = 0.22). When out-door nonsmokers were excluded, passive smoking at work also significantly increased tail length (P = 0.007). Analysis of covariance showed that occupational exposure to traffic exhaust, tobacco smoking, and female had independent effect on lymphocyte DNA damage (P < 0.001) after these factors were adjusted. Passive smoking and age had no effect on lymphocyte DNA damage. CONCLUSIONS: Occupational exposure to traffic exhaust and tobacco smoking respectively increase lymphocyte DNA damage. Female traffic policemen may have more severe DNA damage than male.