Same-Day Discharge for Elective Pediatric Laparoscopic Gastrostomy Tube Insertion is Safe and Increasing in Frequency; a NSQIP Pediatric Retrospective Review 2017 to 2021.

BACKGROUND: There is limited literature reviewing same-day discharge for elective pediatric gastrostomy tube placement. Our aim was to assess the outcomes and national trends of same-day discharge following elective pediatric laparoscopic gastrostomy. METHODS: ACS NSQIP-P registry data from 2017 to 2021 was used to evaluate elective pediatric laparoscopic gastrostomy patients who presented from home and discharged home with a diagnosis of failure to thrive, feeding difficulty or dysphagia. Patients discharged same-day postoperatively (SDD) were compared to those discharged 1-2 days postoperatively (non-SDD) for the primary outcome of unplanned 30-day readmission. Secondary outcomes included bleeding events, wound infection, and 30-day reoperation. RESULTS: There were 5,947 patients identified; 4.7% were discharged same-day. The annual rate of SDD over 5 years went from 2.7% to 4.6%-4.8% to 4.5%-6.3%. There were no significant differences between SDD and non-SDD patients for early readmission or reoperation (0.7% vs 0.3%, p = 0.279), 30-day unplanned readmission (8.5% vs 8.0%, p = 0.407), reoperation (0.1% vs 1.4%, p = 1.000), or any other complications (p > 0.05). Binary logistic regression found pre-operative steroid use within 30 days increased risk of serious complication (OR 2.02, 95% CI 1.29-3.15, p = 0.002) and 30-day readmission or reoperation (OR 2.10, 95% CI 1.34-3.27, p = 0.001). All 6 patients (0.1%) who required reoperation within 3 days were identified prior to discharge, and none of the 16 patients readmitted within 3 days of surgery required reoperation. CONCLUSION: Though rates of same-day discharge following pediatric gastrostomy tube placement are low, they continue to increase annually. There were no significant differences in outcomes between same-day and non-same-day day discharge for elective cases presenting from and discharging home. In non-steroid using patients, same-day discharge following laparoscopic gastrostomy can be a safe option. LEVEL OF EVIDENCE (I-V): Level III.

Computational Prediction of Multiple Antigen Epitopes.

MOTIVATION: Identifying antigen epitopes is essential in medical applications, such as immunodiagnostic reagent discovery, vaccine design, and drug development. Computational approaches can complement low-throughput, time-consuming, and costly experimental determination of epitopes. Currently available prediction methods, however, have moderate success predicting epitopes, which limits their applicability. Epitope prediction is further complicated by the fact that multiple epitopes may be located on the same antigen and complete experimental data is often unavailable. RESULTS: Here, we introduce the antigen epitope prediction program ISPIPab that combines information from two feature-based methods and a docking-based method. We demonstrate that ISPIPab outperforms each of its individual classifiers as well as other state-of-the-art methods, including those designed specifically for epitope prediction. By combining the prediction algorithm with hierarchical clustering, we show that we can effectively capture epitopes that align with available experimental data while also revealing additional novel targets for future experimental investigations. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Operative Timing for Elective Thoracoscopic Lobectomy for CPAM and Sequestration: A NSQIP-Pediatric Analysis 2017-2021.

BACKGROUND: There is limited literature on optimal timing for elective thoracoscopic lobectomy for congenital pulmonary airway malformations (CPAM) and sequestration. Using NSQIP-P, we aim to assess optimal operative timing for elective thoracoscopic lobectomy for CPAM and sequestration. METHODS: Data from the NSQIP-Pediatric registry was used to evaluate elective thoracoscopic lobectomy patients from 2017 to 2021 diagnosed with congenital pulmonary airway malformation or sequestration. Open lobectomy, ventilator dependent, oxygen dependent, and patients <1 month old were excluded. Clinical characteristics and outcomes were compared for age cohorts (in months): 1-3, 3-6, 6-9, 9-12, 12-24, and 24+. RESULTS: There were 717 patients identified. Operative time significantly increased with age from 1 to 3 months to the 24+ month cohort (164.9 min-221.7 min, p = 0.014). Rates of conversion to open were 7.4% vs 21.8%, p = 0.181 in these age groups, respectively. Though not statistically significant, 14.8% of patients at 1-3 months had transfusion events reported compared to 6.4% at 3-6 months and 1.3% at 24+ months (p = 0.067). There were no significant differences between age groups for 30-day unplanned readmission, reoperation, non-transfusion complications, all complications, or mortality. CONCLUSION: Optimal surgical timing for thoracoscopic lobectomy for CPAM and sequestration is complex. Surgery at younger ages is associated with significantly shorter operative times; however, a greater powered study is needed to further assess the conversion to open rate in patients >3 months and the bleeding/transfusion rate in patients <3 months of age. LEVEL OF EVIDENCE (I-V): Level III.

Computational Methods to Predict Conformational B-Cell Epitopes.

Accurate computational prediction of B-cell epitopes can greatly enhance biomedical research and rapidly advance efforts to develop therapeutics, monoclonal antibodies, vaccines, and immunodiagnostic reagents. Previous research efforts have primarily focused on the development of computational methods to predict linear epitopes rather than conformational epitopes; however, the latter is much more biologically predominant. Several conformational B-cell epitope prediction methods have recently been published, but their predictive performances are weak. Here, we present a review of the latest computational methods and assess their performances on a diverse test set of 29 non-redundant unbound antigen structures. Our results demonstrate that ISPIPab performs better than most methods and compares favorably with other recent antigen-specific methods. Finally, we suggest new strategies and opportunities to improve computational predictions of conformational B-cell epitopes.

Computational Prediction of Multiple Antigen Epitopes.

Motivation: Identifying antigen epitopes is essential in medical applications, such as immunodiagnostic reagent discovery, vaccine design, and drug development. Computational approaches can complement low-throughput, time-consuming, and costly experimental determination of epitopes. Currently available prediction methods, however, have moderate success predicting epitopes, which limits their applicability. Epitope prediction is further complicated by the fact that multiple epitopes may be located on the same antigen and complete experimental data is often unavailable. Results: Here, we introduce the antigen epitope prediction program ISPIPab that combines information from two feature-based methods and a docking-based method. We demonstrate that ISPIPab outperforms each of its individual classifiers as well as other state-of-the-art methods, including those designed specifically for epitope prediction. By combining the prediction algorithm with hierarchical clustering, we show that we can effectively capture epitopes that align with available experimental data while also revealing additional novel targets for future experimental investigations. Contact: raji@yu.edu. Supplementary information: Supplementary data are available at Bioinformatics online.

Semi-crystalline materials for pharmaceutical fused filament fabrication: Dissolution and porosity.

A better understanding of crystallization kinetics and the effect on drug product quality characteristics is needed to exploit the use of semi-crystalline polymers in pharmaceutical fused filament fabrication. Filaments were prepared from polycaprolactone or polyethylene oxide loaded with a crystallization inhibitor or inducer, which was either 10% (w/w) ibuprofen or theophylline. A design-of-experiments approach was conducted to investigate the effect of nozzle temperature, bed temperature and print speed on the printed tablets' microstructure and dissolution kinetics. Helium pycnometry derived porosity proved an ideal technique to capture significant distortions in the tablets' microstructure. On the other hand, terahertz time domain spectroscopy (THz-TDS) analysis proved valuable to investigate additional enclosed pores of the tablets' microstructure. The surface roughness was analyzed using optical coherence tomography, showing the importance of extensional viscosity for printed drug products. Drug release occurred via erosion for tablets consisting of polyethylene oxide, which partly reduced the effect of the inner microstructure on the drug release kinetics. An initial burst release effect was noted for polycaprolactone tablets, after which drug release continued via diffusion. Both the pore and crystalline microstructure were deemed essential to steer drug release. In conclusion, this research provided guidelines for material and process choice when a specific microstructure has to be constructed from semi-crystalline materials. In addition, non-destructive tests for the characterization of printed products were evaluated.

The Multifaceted Effects of Osteocytic TGFß Signaling on the Skeletal and Extraskeletal Functions of Bone.

PURPOSE OF REVIEW: To summarize the fundamental role of transforming growth factor beta (TGFß) signaling in osteocytes and highlight the physiological and pathophysiological conditions stemming from the deregulation of this pathway in osteocytes. RECENT FINDINGS: Osteocytes perform a myriad of skeletal and extraskeletal functions, including mechanosensing, coordinating bone remodeling, local bone matrix turnover, and maintaining systemic mineral homeostasis and global energy balance. Transforming growth factor-beta (TGFß) signaling, which is crucial for embryonic and postnatal bone development and maintenance, has been found to be essential for several osteocyte functions. There is some evidence that TGFß might be accomplishing these functions through crosstalk with the Wnt, PTH, and YAP/TAZ pathways in osteocytes, and a better understanding of this complex molecular network can help identify the pivotal convergence points responsible for distinct osteocyte functions. This review provides recent updates on the interwoven signaling cascades coordinated by TGFß signaling within osteocytes to support their skeletal and extraskeletal functions and highlights physiological and pathophysiological conditions implicating the role of TGFß signaling in osteocytes.

Invasion of spontaneous germinal centers by naive B cells is rapid and persistent.

In autoreactive germinal centers (GC) initiated by a single rogue B cell clone, wild-type B cells expand and give rise to clones that target other autoantigens, known as epitope spreading. The chronic, progressive nature of epitope spreading calls for early interventions, but the kinetics and molecular requirements for wild-type B cell invasion and participation in GC remain largely unknown. With parabiosis and adoptive transfer approaches in a murine model of systemic lupus erythematosus, we demonstrate that wild-type B cells join existing GCs rapidly, clonally expand, persist, and contribute to autoantibody production and diversification. The invasion of autoreactive GCs required TLR7, B cell receptor specificity, antigen presentation, and type I interferon signaling. The adoptive transfer model provides a novel tool for identifying early events in the breaking of B cell tolerance in autoimmunity.

Validity of common physical function tests performed online for older adults.

BACKGROUND: Objectively measured physical function tests are important predictors of institutionalization, disability, and premature mortality. Although physical function was usually assessed in person prior to the COVID-19 pandemic, there is a need to investigate whether physical function tests performed online are valid. OBJECTIVE: The purpose of this study was to determine the validity of common physical function tests conducted online compared to in-person testing in older adults. METHODS: Physical functions included gait speed, one leg stance balance, 30-second chair stands, and the 2-minute steps were tested online and in-person using a random order for community dwellers aged 65 years and above. Using an alpha two way mixed model, average intraclass correlation coefficients (ICC) were calculated between the two settings and one sample T-test performed on the difference between the results of each test between the two settings. Finally, Bland-Altman plots were created, and proportional biases tested via linear regressions. RESULTS: Besides the one-leg stance balance with eyes closed, for which the ICC was 0.47 (0.23-0.74) the average ICC's were excellent ranging from 0.87 to 0.94. No proportional biases were observed based on Bland-Altman graphs. CONCLUSION: For older adults living in the community, common physical function tests can be performed online.

Random mucosal rotating flaps for rostral to mid maxillary defect reconstruction: 26 dogs (2000-2019).

OBJECTIVES: To evaluate the feasibility and the complications following single or double random mucosal rotating (transposition or interpolation) flaps for the closure of rostral to mid maxillary defects in dogs. MATERIALS AND METHODS: Medical records of dogs treated with single or double random mucosal rotating flaps after maxillectomy for oral lesions or traumatic loss of tissue, were evaluated. Clinical findings, surgery performed, outcome and postoperative complications (major and minor) were extracted. RESULTS: Twenty-six client-owned dogs were retrospectively included. Dogs underwent maxillectomy for canine acanthomatous ameloblastomas (9), oral squamous cell carcinomas (4), peripheral odontogenic fibromas (4), oral melanomas (3), oral fibrosarcomas (2), dentigerous cysts (2) and oral osteosarcoma (1) and trauma resulting in an oronasal fistula (1). Twenty-three dogs underwent a single transposition or interpolation flap and three dogs were treated with a double transposition flap. Postoperative complications, including dehiscence or flap necrosis, occurred in six dogs. CLINICAL SIGNIFICANCE: Random mucosal rotating (transposition or interpolation) flaps are versatile when used to close rostral maxillary defects in dogs. Postoperative complications appear to be more likely when these flaps are used to close mid maxillary defects.

Bariatric surgery practice patterns among pediatric surgeons in the United States.

BACKGROUND: Metabolic and bariatric surgery (MBS) in adolescents has been shown to be safe and effective, but current practice patterns are variable and poorly understood. The aim of this study is to assess current MBS practice patterns among pediatric surgeons in the United States. METHODS: American Pediatric Surgical Association members were surveyed on current bariatric surgery practices. RESULTS: Four hundred and three (40%) surgeons out of a total of 1013 pediatric surgeons responded to the survey. Only 2 respondents had additional training in MBS (0.5%). One hundred thirty-two (32.6%) report that their practice participates in metabolic and bariatric surgery, with 123 (30.4%) having a specific partner specializing in MBS. Most respondents (92%) stated that they believe high volume is associated with better outcomes with regard to MBS. Only 17 (4.2%) surgeons performed a metabolic and bariatric surgery in the last year. All routinely perform sleeve gastrectomy as their primary procedure. Most (82%) perform procedures with an additional surgeon, either another pediatric surgeon (47%) or an adult bariatric surgeon (47%). All pediatric bariatric surgeons responded that they believe high volume led to better outcomes. Adolescent MBS programs most commonly included pediatric nutritionists (94%), pediatric psychologists (94%), clinical nurses (71%), clinical coordinators (59%), pediatric endocrinologists (59%), and exercise physiologists (52%). CONCLUSION: Only 17 (4.2%) respondents had performed a metabolic and bariatric surgery in the past year, and few of those had additional training in MBS. Future work is necessary to better understand optimal practice patterns for adolescent metabolic and bariatric surgery. TYPE OF STUDY: Review article. LEVEL OF EVIDENCE: Level III.

Integrated structure-based protein interface prediction.

BACKGROUND: Identifying protein interfaces can inform how proteins interact with their binding partners, uncover the regulatory mechanisms that control biological functions and guide the development of novel therapeutic agents. A variety of computational approaches have been developed for predicting a protein's interfacial residues from its known sequence and structure. Methods using the known three-dimensional structures of proteins can be template-based or template-free. Template-based methods have limited success in predicting interfaces when homologues with known complex structures are not available to use as templates. The prediction performance of template-free methods that only rely only upon proteins' intrinsic properties is limited by the amount of biologically relevant features that can be included in an interface prediction model. RESULTS: We describe the development of an integrated method for protein interface prediction (ISPIP) to explore the hypothesis that the efficacy of a computational prediction method of protein binding sites can be enhanced by using a combination of methods that rely on orthogonal structure-based properties of a query protein, combining and balancing both template-free and template-based features. ISPIP is a method that integrates these approaches through simple linear or logistic regression models and more complex decision tree models. On a diverse test set of 156 query proteins, ISPIP outperforms each of its individual classifiers in identifying protein binding interfaces. CONCLUSIONS: The integrated method captures the best performance of individual classifiers and delivers an improved interface prediction. The method is robust and performs well even when one of the individual classifiers performs poorly on a particular query protein. This work demonstrates that integrating orthogonal methods that depend on different structural properties of proteins performs better at interface prediction than any individual classifier alone.

Intraoperative uses of near-infrared fluorescence spectroscopy in pediatric surgery: A systematic review.

BACKGROUND: The application of near infrared spectroscopy (NIRS) imaging in surgery is growing. This study aimed to systematically review the literature to summarize the intraoperative uses of NIRS in pediatric surgery. METHODS: A PRISMA-compliant literature search was conducted in PubMed, Embase, Scopus, and Web of Science from inception to February 2020. Title/abstract and then full-text screening were performed. The Oxford centre for Evidence Based Medicine tool (OCEBM) was used to evaluate the level of evidence of included studies. RESULTS: Reviewers identified 53 articles. Of which, 34 studies (64.2%) were case-series and 11 (20.8%) were case reports. Most of the studies (n = 45, 84.9%) were level 4 on the OCEBM tool. The most common uses of NIRS were to visualize the biliary tree and to identify primary and metastatic malignant tissues. Other applications include assessment of perfusion of tissues including bowel anastomoses, and lymphatic surgery. Several advantages of the introduction of NIRS in pediatric surgery exist including having the potential to reduce operative time and intra/post-operative complications. Moreover, NIRS helps in detecting malignant tissues that can be missed by conventional imaging. However, NIRS has important limitations such as difficulty in identification of the biliary tree in obese patients or inflamed gallbladder, detection of small deeply localized malignant tissues, as well as the high cost. CONCLUSIONS: NIRS is a promising modality that can be used intraoperatively to augment different pediatric surgical procedures. NIRS has important advantages and limitations compared to conventional surgery, however, more studies are required to evaluate its outcomes and cost-effectiveness. LEVEL OF EVIDENCE: IV.

High prevalence of subnormal testosterone in obese adolescent males: reversal with bariatric surgery.

OBJECTIVE: Obesity in adolescent males is associated with the lowering of total and free testosterone concentrations. Weight loss may increase testosterone concentrations. DESIGN AND METHODS: We evaluated the changes in sex hormones following bariatric surgery in 34 males (age range: 14.6-19.8 years) with obesity. These participants were part of a prospective multicenter study, Teen-Longitudinal Assessment of Bariatric Surgery. The participants were followed up for 5 years after surgery. Total testosterone, total estradiol, luteinizing hormone, follicle-stimulating hormone, sex hormone-binding globulin, C-reactive protein, insulin and glucose were measured at baseline, 6 months and annually thereafter. Free testosterone, free estradiol and HOMA2-IR were calculated. RESULTS: Study participants lost one-third of their body weight after bariatric surgery, with maximum weight loss achieved at 24 months for most participants. Free testosterone increased from 0.17 (95% CI: 0.13 to 0.20) at baseline to 0.34 (95% CI: 0.30 to 0.38) and 0.27 nmol/L (95% CI: 0.23 to 0.32) at 2 and 5 years (P < 0.001 for both), respectively. Total testosterone increased from 6.7 (95% CI: 4.7 to 8.8) at baseline to 17.6 (95% CI: 15.3 to 19.9) and 13.8 (95% CI: 11.0 to 16.5) nmol/L at 2 and 5 years (P < 0.001), respectively. Prior to surgery, 73% of the participants had subnormal free testosterone (<0.23 nmol/L). After 2 and 5 years, only 20 and 33%, respectively, had subnormal free testosterone concentrations. Weight regain was related to a fall in free testosterone concentrations. CONCLUSIONS: Bariatric surgery led to a robust increase in testosterone concentrations in adolescent males with severe obesity. Participants who regained weight had a decline in their testosterone concentrations.

The Phenotypic Spectrum of New-onset IBD in Canadian Children of South Asian Ethnicity: A Prospective Multi-Centre Comparative Study.

BACKGROUND: Canadian-born children of South Asian [SA] ethnicity develop inflammatory bowel disease [IBD] at similar rates to those among Caucasian children. We evaluated the variation in phenotypic spectrum of IBD in SA and Caucasian children in a national paediatric inception cohort of new-onset IBD. METHODS: Patients aged <17 years, enrolled in a Canadian nationwide inception cohort study, were included. Baseline demographic and IBD phenotypic features were compared between SA and Caucasian children. Longitudinal outcomes through 18 months of follow-up were compared matched by propensity scores. RESULTS: Of 1156 children enrolled over 2014 to 2019, 623 were Caucasian [98% and 88% parents Canadian born] and 114 SA [79% Canadian born, 87% parents SA born]. Fewer SAs have a first-degree relative with IBD, 6% vs 19% in Caucasians, p = 0.002. SAs present at a younger age, median age 11.4 years (interquartile range [IQR] 9.2-14.3) vs 13 years [IQR 10.9-15 years], p = 0.03 and more commonly with a UC/IBD-U [ulcerative colitis/IBD-unclassified] subtype [ratio of UC/IBD-U to CD 1.2:1 vs 1:1.8 for Caucasians, p <0.001]. Additionally, a greater proportion of SA CD patients present with colonic-only disease [colonic-only CD/UC/IBD-U in SAs 67% vs 57% for Caucasians, p = 0.001], and among those with CD, colonic CD in SAs 31% vs 23% in Caucasians, p = 0.20]. Perianal fistulising disease was also numerically more common in SAs (14 [27%] vs 64 [18%], p = 0.06]. Adjusting for differences in phenotypic presentation, anti-tumour necrosis factor [TNF] exposure, and time to initiation was similar, and two-thirds of children, whether anti-TNF exposed or naïve, were in corticosteroid-free clinical remission at 18 months irrespective of ethnicity. CONCLUSIONS: The phenotypic spectrum of new-onset IBD in SA children differs from that of Caucasian children, but treatment and clinical course are similar within phenotypic subgroups.

Initial Laparotomy Versus Peritoneal Drainage in Extremely Low Birthweight Infants With Surgical Necrotizing Enterocolitis or Isolated Intestinal Perforation: A Multicenter Randomized Clinical Trial.

OBJECTIVE: The aim of this study was to determine which initial surgical treatment results in the lowest rate of death or neurodevelopmental impairment (NDI) in premature infants with necrotizing enterocolitis (NEC) or isolated intestinal perforation (IP). SUMMARY BACKGROUND DATA: The impact of initial laparotomy versus peritoneal drainage for NEC or IP on the rate of death or NDI in extremely low birth weight infants is unknown. METHODS: We conducted the largest feasible randomized trial in 20 US centers, comparing initial laparotomy versus peritoneal drainage. The primary outcome was a composite of death or NDI at 18 to 22 months corrected age, analyzed using prespecified frequentist and Bayesian approaches. RESULTS: Of 992 eligible infants, 310 were randomized and 96% had primary outcome assessed. Death or NDI occurred in 69% of infants in the laparotomy group versus 70% with drainage [adjusted relative risk (aRR) 1.0; 95% confidence interval (CI): 0.87-1.14]. A preplanned analysis identified an interaction between preoperative diagnosis and treatment group (P = 0.03). With a preoperative diagnosis of NEC, death or NDI occurred in 69% after laparotomy versus 85% with drainage (aRR 0.81; 95% CI: 0.64-1.04). The Bayesian posterior probability that laparotomy was beneficial (risk difference <0) for a preoperative diagnosis of NEC was 97%. For preoperative diagnosis of IP, death or NDI occurred in 69% after laparotomy versus 63% with drainage (aRR, 1.11; 95% CI: 0.95-1.31); Bayesian probability of benefit with laparotomy = 18%. CONCLUSIONS: There was no overall difference in death or NDI rates at 18 to 22 months corrected age between initial laparotomy versus drainage. However, the preoperative diagnosis of NEC or IP modified the impact of initial treatment.

Preventing abusive head trauma: can educating parents reduce the incidence?

Abusive head trauma (AHT) is the most lethal form of child abuse; preventing AHT should be a national priority, but research into this area is woefully underfunded. Prevention programs have primarily focused on universal parent education during the neonatal period, a time when parents are a captive audience of the health care establishment whose focus is on the needs of their newborn infant, and who will soon be exposed to the frustration and anger of infant crying. Research has suggested a strong causal link between infant crying and AHT, and parents - particularly fathers and father figures - have been identified as the most common perpetrators of AHT. A number of studies have suggested that educating parents during the postnatal period about the normalcy of inconsolable infant crying and its evolution over the first several months of postnatal life improves parental knowledge about infant crying and a number of positive parenting behaviors, and decreases emergency room visits for crying. In 1998, we began a pilot program in Upstate New York near Buffalo that led to a 47% reduction in AHT incidence. Similar studies have demonstrated 35-75% reductions in incidence, which has led to enthusiasm for this approach to preventing AHT. We, as well as another group, have enacted statewide programs in Pennsylvania and North Carolina; unfortunately, these two large statewide replication trials failed to demonstrate any impact of such an intervention on AHT rates. Serial messages for parents, provided repeatedly over the period of greatest risk for AHT, might be another avenue of research.

The marker of alkyl DNA base damage, N7-methylguanine, is associated with semen quality in men.

Sperm DNA contains a range of DNA base damage that can arise, in part, from exposure to methylating agents. However, the effects are not fully characterized and so the aim of this study was to investigate associations between semen quality and the levels of N7-methyldeoxyguanosine (N7-MedG), a marker of exposure to methylating agents, and other markers of DNA damage and DNA methylation. Sperm samples were collected from 105 men attending an assisted reproduction clinic as part of a couple undergoing treatment for infertility and semen quality assessed manually according to WHO guidelines. Semen levels of N7-MedG, quantified by immunoslotblot, were significantly higher in men with sperm concentration < 15 × 106/ml (p ≤ 0.01), semen volume < 1.5 ml (p ≤ 0.05) and also in men with any aspect of semen quality below WHO reference levels (p ≤ 0.001). Measures of neutral Comet DNA damage were correlated with semen quality in a univariate analysis but not after adjustment for N7-MedG levels. Sperm concentration was negatively associated with % methylation at the gene for DAZL but no other marker of global or gene-specific DNA methylation. Results support the hypothesis that the known toxic and DNA damaging properties of alkylating agent exposure may have direct deleterious consequences on semen quality.