Sex Differences in Track and Field Elite Youth.

PURPOSE: To understand athletic performance before and after puberty, this study determined: 1) the age at which the sex difference increases among elite youth track and field athletes for running and jumping events; and 2) whether there is a sex difference in performance prior to ages associated with puberty among elite youth athletes. METHODS: Track and field records of elite USA male and female youth (7-18 years) across three years (2019, 2021, and 2022) were collected from an online database ( athletic.net ). The top 50 performances were recorded for 100 m, 200 m, 400 m, and 800 m track running, long jump, and high jump. RESULTS: Males ran faster than females at every age in the 100, 200, 400 and 800 m ( P < 0.001). When combining all running events, the sex difference (%) was 4.0 ± 1.7% between 7-12 years and increased to 6.3 ± 1.1% at 13 years, and 12.6 ± 1.8% at 18 years ( P < 0.001). Similarly, males jumped higher and farther than females at every age ( P < 0.001). For long jump, the sex difference was 6.8 ± 2.8% between 7-12 years, increasing to 8.5 ± 1.7% at 13 years, and 22.7 ± 1.4% at 18 years ( P < 0.001). For high jump, the sex difference was 5.3 ± 5.2% between 7-12 years, increasing to 12.4 ± 2.9% at 15 years, and 18.4 ± 2.04% at 18 years ( P < 0.001). CONCLUSIONS: Prior to 12 years of age in elite youth track and field athletes, there was a consistent and significant sex difference of ~5%, such that males ran faster and jumped higher and farther than females. The magnitude of the sex difference in performance increased markedly at 12-13 years for running and long jump and 14 years for high jump and thus was more pronounced after ages associated with puberty.

Characteristics of pulse oximetry and arterial blood gas in patients with fibrotic interstitial lung disease.

BACKGROUND: Fibrotic interstitial lung disease (ILD) is frequently associated with abnormal oxygenation; however, little is known about the accuracy of oxygen saturation by pulse oximetry (SpO2) compared with arterial blood gas (ABG) saturation (SaO2), the factors that influence the partial pressure of carbon dioxide (PaCO2) and the impact of PaCO2 on outcomes in patients with fibrotic ILD. STUDY DESIGN AND METHODS: Patients with fibrotic ILD enrolled in a large prospective registry with a room air ABG were included. Prespecified analyses included testing the correlation between SaO2 and SpO2, the difference between SaO2 and SpO2, the association of baseline characteristics with both the difference between SaO2 and SpO2 and the PaCO2, the association of baseline characteristics with acid-base category, and the association of PaCO2 and acid-base category with time to death or transplant. RESULTS: A total of 532 patients with fibrotic ILD were included. Mean resting SaO2 was 92±4% and SpO2 was 95±3%. Mean PaCO2 was 38±6 mmHg, with 135 patients having PaCO2 <35 mmHg and 62 having PaCO2 >45 mmHg. Correlation between SaO2 and SpO2 was mild to moderate (r=0.39), with SpO2 on average 3.0% higher than SaO2. No baseline characteristics were associated with the difference in SaO2 and SpO2. Variables associated with either elevated or abnormal (elevated or low) PaCO2 included higher smoking pack-years and lower baseline forced vital capacity (FVC). Lower baseline lung function was associated with an increased risk of chronic respiratory acidosis. PaCO2 and acid-base status were not associated with time to death or transplant. INTERPRETATION: SaO2 and SpO2 are weakly-to-moderately correlated in fibrotic ILD, with limited ability to accurately predict this difference. Abnormal PaCO2 was associated with baseline FVC but was not associated with outcomes.

Age-related changes in human skeletal muscle transcriptome and proteome are more affected by chronic inflammation and physical inactivity than primary aging.

Evaluation of the influence of primary and secondary aging on the manifestation of molecular and cellular hallmarks of aging is a challenging and currently unresolved issue. Our study represents the first demonstration of the distinct role of primary aging and chronic inflammation/physical inactivity - the most important drivers of secondary aging, in the regulation of transcriptomic and proteomic profiles in human skeletal muscle. To achieve this purpose, young healthy people (n = 15), young (n = 8) and older (n = 37) patients with knee/hip osteoarthritis, a model to study the effect of long-term inactivity and chronic inflammation on the vastus lateralis muscle, were included in the study. It was revealed that widespread and substantial age-related changes in gene expression in older patients relative to young healthy people (~4000 genes regulating mitochondrial function, proteostasis, cell membrane, secretory and immune response) were related to the long-term physical inactivity and chronic inflammation rather than primary aging. Primary aging contributed mainly to the regulation of genes (~200) encoding nuclear proteins (regulators of DNA repair, RNA processing, and transcription), mitochondrial proteins (genes encoding respiratory enzymes, mitochondrial complex assembly factors, regulators of cristae formation and mitochondrial reactive oxygen species production), as well as regulators of proteostasis. It was found that proteins associated with aging were regulated mainly at the post-transcriptional level. The set of putative primary aging genes and their potential transcriptional regulators can be used as a resource for further targeted studies investigating the role of individual genes and related transcription factors in the emergence of a senescent cell phenotype.

Impact of Periodontitis on the Leakage of Oral Bacteria to the Gut.

Colorectal cancer (CRC) and periodontitis have recently been related due to the higher incidence of CRC in periodontal patients and the involvement of periodontal pathogens in carcinogenesis, suggesting that leakage from the oral cavity to the gut occurs. However, the magnitude of this pass-through in healthy individuals is controversial, and the effect that periodontitis could play in it is understudied. To evaluate the rate of bacterial leakage from the oral cavity to the gut, we analyzed the microbial composition of saliva, subgingival plaque, and fecal samples in healthy individuals without gastrointestinal disorders, including 20 periodontitis patients and 20 oral healthy controls, using PacBio full-length 16S rRNA gene sequencing. As expected, we observed a higher abundance of periodontal pathogens in the subgingival plaque and saliva of periodontal patients. In contrast, no significant differences were found between the fecal samples of both groups, implying that gut samples from periodontal patients were not enriched in periodontal pathogens. Fusobacterium nucleatum, a biomarker of CRC, was not found in the fecal samples of any participant. Our study does show a small leakage of some oral bacteria (mainly streptococci) to the gut, regardless of periodontal health status. Future studies should test whether other host factors and/or the preexistence of a gut disorder must be present in addition to periodontitis to promote the colonization of the gut by oral pathogens. The absence of periodontal pathogens in feces supports the idea that these bacteria could be used as biomarkers of intestinal disorders, including CRC.

Integrated behavioral health services in pediatric primary care and emergency department utilization for suicide risk.

Introduction: Universal screening for suicide risk in primary care settings is a promising avenue for preventing self-harm and improving health outcomes. Triaging youth to an appropriate level of care, including diverting lower-risk patients from the emergency department (ED) is a meaningful goal. Previous research indicates integrated behavioral health (IBH) may prevent unnecessary admission to the ED on the day of suicide risk screening. We hypothesized that youth who received an IBH consultation the same day as suicide risk screening would be less likely to be admitted to the ED, but more likely to contact IBH services and utilize primary care in the following month. Methods: We conducted a retrospective chart review of 3,649 youth aged 10-18 years who were screened with the Ask Suicide-Screening Questions (ASQ) in two pediatric primary care practices. We collected demographic data, ASQ and Patient Health Questionnaire-9 (PHQ-9) scores, as well as patient contacts with IBH, the ED, and medical primary care the day of screening and the following 31 days. We conducted a series of logistic regressions and chi-square analyses to determine whether contact with IBH on the same day as positive suicide risk screenings predicted same-day admission to the ED, IBH contact, and medical primary care utilization. Results: Among the 7,982 ASQ scores, 1,380 (18%) were non-acute and 87 ASQs (1%) screened acutely positive. Over 90% of positive screens were diverted from the ED regardless of IBH contact. None of the patients died from suicide. Same-day IBH was associated with higher likelihood of general ED visits for all positive screens (acute and non-acute together). None of the positive screens that received an IBH consultation on the same day as screening were admitted to the ED in the subsequent month. Contact with IBH the same day as screening positively predicted utilization of IBH and medical primary care services in the subsequent month, especially for youth with minority race and ethnicity identities. Discussion: In the context of clinics with IBH and systematic risk assessment processes, most youth who screen positive for suicide risk are diverted from the ED. However, contrary to our hypothesis, our study showed that youth who received same-day IBH consultations were more likely to be admitted to the ED compared to peers who did not receive IBH consultations. These findings suggest that systematic suicide screening combined with IBH consultations in pediatric primary care can effectively identify risk levels and triage patients to appropriate care.

2,2'-Bithiophene as sensor tag for ligand-protein binding assays based on Förster resonance energy transfer.

Ligand-protein binding assays based on intrinsic protein fluorescence are straightforward, inexpensive methods to study ligand-protein interactions. However, their applicability is limited to ligands that can interfere with protein emission. In this Note, we describe the applicability of 2,2'-bithiophene as a FRET-based sensor tag, that can be incorporated into high-affinity ligands to generate target-specific compounds able to quench protein fluorescence upon binding. The generated ligands were assessed in different assay designs. Considerations to account for possible sources of interference with the assay readout are addressed, besides interpretation of the obtained results.

Nasopharyngeal Swabs in Pediatric Patients With Thrombocytopenia and Anticoagulant Use.

BACKGROUND: Nasopharyngeal (NP) swabbing is a technique that is commonly used to test pediatric patients for viral infections with increased use during the coronavirus disease 2019 pandemic. Complications from NP swabbing are rare and seem to occur more frequently in patients at risk of bleeding. Little is known about institutional or individual practices and experiences with NP swab testing in pediatric patients with risk factors for bleeding. METHODS: We conducted a survey study of pediatric hematology/oncology (PHO) attending physicians to assess practices and experiences with NP swab testing in pediatric patients with thrombocytopenia and/or on anticoagulation. RESULTS: There were 130 total respondents (5.6%, n = 130/2327) from 6 countries. Relatively few respondents (n = 17/130, 13.1%) reported that their institution had a policy specifying a lower-level platelet cutoff for patients undergoing NP swabbing. The median platelet cutoff below which NP swabs are not performed according to existing policies is 30,000×10(9)/L (interquartile range: 20,000 to 40,000). The median cutoff based on the opinion of the respondents was 10,000 (interquartile range: 10,000 to 20,000). There were 24 episodes of epistaxis among PHO patients that were NP swabbed; many adverse events (56.5%, n = 13/23) were described as persistent, severe, and/or required intervention. Three reported cases of epistaxis with anticoagulation or antiplatelet therapy occurred in patients with concomitant thrombocytopenia. Only 1 respondent (n = 1/130, 0.7%) reported an institutional policy for limiting NP swabs in patients on anticoagulant therapy. NP (66.9%) and nares (33.1%) were the most common sources of coronavirus disease 2019 testing that were reported. CONCLUSION: A small percentage of institutions in this survey have a policy restricting NP swabs in PHO patients. The discrepancy between lower platelet cutoffs proposed by experts and institutional policy suggests that existing policies may be too conservative. Expert guidelines are needed on this topic. Other bleeding risk factors (eg, aspirin use and von Willebrand disease) should be considered in policies and guidelines.

Underrepresentation of women in exercise science and physiology research is associated with authorship gender.

Historically, low representation of women participants in exercise science and physiology studies has led to a lack of understanding in the response of women to exercise and therapeutic interventions. We hypothesized that 1) the number of women authors, participants, and editorial board members increased over 30 years (1991-2021) and 2) larger representation of women as editors and authors is associated with more women participants. Gender (man/woman) of editorial board members (n = 394), authors (n = 5,735), and participants (n = 2,984,883) of 972 original research articles with human participants published in 1991 and 2021 was analyzed from three journals: Journal of Applied Physiology, Medicine and Science in Sports and Exercise, and British Journal of Sports Medicine. Between 1991 to 2021, the average percent women per article as participants (21.9 ± 31.7% vs. 36.3 ± 30.3%, respectively, P < 0.001), authors (16.4 ± 22.4% vs. 30.9 ± 24.0%, P < 0.001), and editorial board members (13.3 ± 5.4% vs. 41.5 ± 7.3%, P = 0.006) increased. In 2021, the gender proportion of participants in large datasets was similar (50.2 ± 20.2% women). However, studies with smaller datasets (i.e., <∼3,000 participants) included less women (35.6 ± 30.6%). Women participants (%) were less when the last author was a man rather than a woman in 1991 (19.9 ± 29.5% vs. 34.3 ± 42.2%) and 2021 (31.6 ± 27.7% vs. 51.7 ± 33.4%). In 2021, there was a positive correlation between author and participant gender (% women) (r = 0.42, P < 0.001). Our data suggest that the low representation of women in exercise science and physiology research could be resolved with equitable numbers of women authors and editors and by encouraging men authors to study both women and men participants.NEW & NOTEWORTHY Analysis of human applied physiology studies revealed that the representation of women authors, participants, and editorial board members increased over 30 years but remained lower than men in 2021. Larger representation of women editors and authors was associated with more women participants. Women authors assessed similar numbers of women and men participants, whereas men authors included less women. Equitable representation of women participants may be achieved by closing the gender gap in authorship and editorial board membership.

Demographic predictors of emergency service utilization patterns in youth at risk of suicide.

OBJECTIVE: To explore demographic predictors of Emergency Department (ED) utilization among youth with a history of suicidality (i.e., ideation or behaviors). METHODS: Electronic health records were extracted from 2017 to 2021 for 3094 8-22 year-old patients with a history of suicidality at an urban academic medical center ED in the Mid-Atlantic. Logistic regression analyses were used to assess for demographic predictors of ED utilization frequency, timing of subsequent visits, and reasons for subsequent visits over a 24-month follow-up period. RESULTS: Black race (OR = 1.45, 95% CI = 1.11-1.92), Female sex (OR = 1.59, 95% CI = 1.26-2.03), and having Medicaid insurance (OR = 1.71, 95% CI = 1.37-2.14) were associated with increased utilization, while being under 18 was associated with lower utilization (<12: OR = 0.38, 95% CI = 0.26-0.56; 12-18: OR = 0.47, 95% CI = 0.35-0.63). These demographics were also associated with ED readmission within 90 days, while being under 18 was associated with a lower odds of readmission. CONCLUSIONS: Among patients with a history of suicidality, those who identify as Black, young adults, patients with Medicaid, and female patients were more likely to be frequent utilizers of the ED within the 2 years following their initial visit. This pattern may suggest inadequate health care access for these groups, and a need to develop better care coordination with an intersectional focus to facilitate utilization of other health services.

εγ-Thalassemia, a New Hemoglobinopathy Category.

BACKGROUND: Large ß-globin gene cluster deletions (hereditary persistence of fetal hemoglobin [Hb] or ß-, δß-, γδß-, and ϵγδß-thalassemia), are associated with widely disparate phenotypes, including variable degrees of microcytic anemia and Hb F levels. When present, increased Hb A2 is used as a surrogate marker for ß-thalassemia. Notably, ϵγδß-thalassemias lack the essential regulatory locus control region (LCR) and cause severe transient perinatal anemia but normal newborn screen (NBS) results and Hb A2 levels. Herein, we report a novel deletion of the ϵ, Aγ, Gγ, and ψß loci with intact LCR, δ-, and ß-regions in 2 women and newborn twins. METHODS: Capillary electrophoresis (CE), high-performance liquid chromatography (HPLC), DNA sequencing, multiplex ligation-dependent probe amplification (MLPA), gap-polymerase chain reaction (gap-PCR), and long-read sequencing (LRS) were performed. RESULTS: NBS showed an Hb A > Hb F pattern for both twins. At 20 months, Hb A2 was increased similarly to that in the mother and an unrelated woman. Unexplained microcytosis was absent and the twins lacked severe neonatal anemia. MLPA, LRS, and gap-PCR confirmed a 32 599 base pair deletion of ϵ (HBE1) through ψß (HBBP1) loci. CONCLUSIONS: This deletion represents a hemoglobinopathy category with a distinct phenotype that has not been previously described, an ϵγ-thalassemia. Both the NBS Hb A > F pattern and the subsequent increased Hb A2 without microcytosis are unusual. A similar deletion should be considered when this pattern is encountered and appropriate test methods selected for detection. Knowledge of the clinical impact of this new category will improve genetic counselling, with distinction from the severe transient anemia associated with ϵγδß-thalassemia.

The epidemiological and medico-legal characteristics of violent deaths and spousal homicides through a population of women autopsied within the Forensic Medicine Department of the University Hospital of Annaba.

BACKGROUND: Domestic violence is a real public health problem with considerable consequences, ranging from minor injuries to death. Our study aims to determine the epidemiological and forensic characteristics relating to the violent mortality of women, and more particularly spousal homicide. METHODS: To do this, a double survey was conducted. The first step was descriptive and retrospective, and the second survey was analytical and prospective. This latter step covered the most populous age group of murdered women in Algeria, which is eighteen-year-old and over, and subjected a number of these female victims to a medico-judicial autopsy at the level of the thanatology unit for over four years counting two years for each survey (2017-2018 and 2019-2020). Data were entered and processed using Epi-info6 software. RESULTS: During the initial period of our study, we identified 35 cases of violent deaths involving women and representing a frequency of 5.71% of the thanatological activity. During the second period, 12 spousal homicides were recorded and autopsied, representing a frequency of 1.79% of all forensic deaths in the corresponding study period. The average age of the victims was evaluated at 33 ± 12.91 years, with extremes of 19 to 56 years. The age of the perpetrators of spousal homicide was evaluated at 42 ± 10.76 years with extremes ranging from 30 to 60 years. For victims of violent death and spousal homicide, inactivity was a strongly implicated risk factor, with respective frequencies of (88.57%) and (58.33%). Two-thirds of the persecuted women were completely unknown to the healthcare environment and had never consulted a medical professional. This parameter could be one of the predictive signs of spousal homicide. The marital home was the preferred location for violent deaths and spousal homicides. These crimes occurred variably during the period of marriage and eventually after divorce. As for the modus operandi, the perpetrators use many sharp and spinous weapons, including firearms and blunt objects. CONCLUSION: Autopsy and medico-legal investigations took a decisive interest in the identification of the causes of spousal homicide; indeed, many serious traumatic lesions incompatible with life have been highlighted. We underline the crucial role that healthcare professionals must play in the process of identifying and evaluating potentially risky situations.

The Murine Oral Metatranscriptome Reveals Microbial and Host Signatures of Periodontal Disease.

Periodontal disease is accompanied by alterations to cellular profiles and biological activities of both the subgingival microbiome and host tissues. Although significant progress has been made in describing the molecular basis of the homeostatic balance of host-commensal microbe interactions in health compared to the destructive imbalance in disease, particularly with respect to immune and inflammatory systems, few studies have attempted a comprehensive analysis in diverse host models. Here, we describe the development and application of a metatranscriptomic approach to analysis of host-microbe gene transcription in a murine periodontal disease model, based on oral gavage infection using Porphyromonas gingivalis in C57BL6/J mice. We generated 24 metatranscriptomic libraries from individual mouse oral swabs, representing health and disease. On average, 76% ± 11.7% reads in each sample belonged to the murine host genome and the remainder to the microbes. We found 3,468 (2.4% of the total) murine host transcripts differentially expressed between health and disease, of which 76% were overexpressed in periodontitis. Predictably, there were prominent alterations to genes and pathways linked with the host immune compartment in disease-the CD40 signaling pathway being the top enriched biological process in this data set. However, in addition, we observed significant alterations to other biological processes in disease, particularly cellular/metabolic processes and biological regulation. The number of differentially expressed microbial genes particularly indicated shifts in carbon metabolism pathways in disease with potential consequences for metabolic end-product formation. Together, these metatranscriptome data reveal marked changes between the gene expression patterns in both the murine host and microbiota, which may represent signatures of health and disease, providing the basis for future functional studies of prokaryotic and eukaryotic cellular responses in periodontal disease. In addition, the noninvasive protocol developed in this study will enable further longitudinal and interventionist studies of host-microbe gene expression networks.

An Effective Combination Therapy for the Treatment of Pediatric Monomorphic Post-transplant Lymphoproliferative Disorder With Plasmacytic Differentiation.

Post-transplant lymphoproliferative disorder (PTLD) is a complication of immunosuppressive therapy following solid organ or hematopoietic cell transplantation. Initial treatment typically includes a reduction of immunosuppression with or without rituximab. However, the optimal therapy for PTLD with plasmacytic differentiation is unclear. We present 3 cases of pediatric patients with plasmacytic PTLD. Two patients received a standard rituximab-based approach and relapsed, prompting additional chemotherapy. The third patient was treated with a novel regimen of bortezomib, dexamethasone, and daratumumab. This regimen was safe, well-tolerated, and resulted in a 2-year remission. Larger studies are needed to further explore this regimen.

The Effect of Surgeon Referral and a Radiation Oncologist Productivity-Based Metric on Radiation Therapy Receipt Among Elderly Women With Early Stage Breast Cancer: Analysis From a Tertiary Cancer Network.

Purpose: : Guidelines for early-stage breast cancer allow for radiation therapy (RT) omission after breast conserving surgery among older women, though high utilization of RT persists. This study explored surgeon referral and the effect of a productivity-based bonus metric for radiation oncologists in an academic institution with centralized quality assurance review. Methods and materials: : We evaluated patients ≥70 years of age treated with breast conserving surgery for estrogen receptor (ER)+ pT1N0 breast cancer at a single tertiary cancer network between 2015 and 2018. The primary outcomes were radiation oncology referral and RT receipt. Covariables included patient and physician characteristics and treatment decisions before versus after productivity metric implementation. Univariable generalized linear effects models explored associations between these outcomes and covariables. Results: : Of 703 patients included, 483 (69%) were referred to radiation oncology and 273 (39%) received RT (among those referred, 57% received RT). No difference in RT receipt pre- versus post-productivity metric implementation was observed (P = .57). RT receipt was associated with younger patient age (70-74 years; odds ratio [OR], 2.66; 95% confidence interval [CI], 1.54-4.57) and higher grade (grade 3; OR, 7.75; 95% CI, 3.33-18.07). Initial referral was associated with younger age (70-74; OR, 5.64; 95% CI, 3.37-0.45) and higher performance status (Karnofsky performance status ≥90; OR, 5.34; 95% CI, 2.63-10.83). Conclusions: : Nonreferral to radiation oncology accounted for half of RT omission but was based on age and Karnofsky performance status, in accordance with guidelines. Lack of radiation oncologist practice change in response to misaligned financial incentives is reassuring, potentially reflecting incentive design and/or centralized quality assurance review. Multi-institutional studies are needed to confirm these findings.

Tumor-associated microbiome features of metastatic colorectal cancer and clinical implications.

Background: Colon microbiome composition contributes to the pathogenesis of colorectal cancer (CRC) and prognosis. We analyzed 16S rRNA sequencing data from tumor samples of patients with metastatic CRC and determined the clinical implications. Materials and methods: We enrolled 133 patients with metastatic CRC at St. Vincent Hospital in Korea. The V3-V4 regions of the 16S rRNA gene from the tumor DNA were amplified, sequenced on an Illumina MiSeq, and analyzed using the DADA2 package. Results: After excluding samples that retained <5% of the total reads after merging, 120 samples were analyzed. The median age of patients was 63 years (range, 34-82 years), and 76 patients (63.3%) were male. The primary cancer sites were the right colon (27.5%), left colon (30.8%), and rectum (41.7%). All subjects received 5-fluouracil-based systemic chemotherapy. After removing genera with <1% of the total reads in each patient, 523 genera were identified. Rectal origin, high CEA level (≥10 ng/mL), and presence of lung metastasis showed higher richness. Survival analysis revealed that the presence of Prevotella (p = 0.052), Fusobacterium (p = 0.002), Selenomonas (p<0.001), Fretibacterium (p = 0.001), Porphyromonas (p = 0.007), Peptostreptococcus (p = 0.002), and Leptotrichia (p = 0.003) were associated with short overall survival (OS, <24 months), while the presence of Sphingomonas was associated with long OS (p = 0.070). From the multivariate analysis, the presence of Selenomonas (hazard ratio [HR], 6.35; 95% confidence interval [CI], 2.38-16.97; p<0.001) was associated with poor prognosis along with high CEA level. Conclusion: Tumor microbiome features may be useful prognostic biomarkers for metastatic CRC.

The tongue biofilm metatranscriptome identifies metabolic pathways associated with the presence or absence of halitosis.

Intra-oral halitosis usually results from the production of volatile sulfur compounds, such as methyl mercaptan and hydrogen sulfide, by the tongue microbiota. There are currently no reports on the microbial gene-expression profiles of the tongue microbiota in halitosis. In this study, we performed RNAseq of tongue coating samples from individuals with and without halitosis. The activity of Streptococcus (including S. parasanguinis), Veillonella (including V. dispar) and Rothia (including R. mucilaginosa) was associated with halitosis-free individuals while Prevotella (including P. shahi), Fusobacterium (including F. nucleatum) and Leptotrichia were associated with halitosis. Interestingly, the metatranscriptome of patients that only had halitosis levels of methyl mercaptan was similar to that of halitosis-free individuals. Finally, gene expression profiles showed a significant over-expression of genes involved in L-cysteine and L-homocysteine synthesis, as well as nitrate reduction genes, in halitosis-free individuals and an over-expression of genes responsible for cysteine degradation into hydrogen sulfide in halitosis patients.