Sudden death in a newborn from cerebral venous sinus thrombosis resulting from meningitis.

Septic cerebral venous sinus thrombosis is a rare but often fatal complication caused by bacterial meningitis and paranasal sinusitis.We report a particular case of the sudden and unexpected death of a six-day-old infant from unrecognised acute meningitis that caused a thrombotic occlusion of the venous sinuses (with the particular involvement of the torcular Herophili at the confluence of sinuses) resulting in subdural haemorrhage.This case report alerts paediatricians and neonatologists to the importance of promptly considering a possible diagnosis of meningitis without delay to avoid the fatal complications described here. As in all cases of sudden infant death our case study underlines the need for a thorough autopsy, accompanied by histological analysis, in order to identify the causes of the underlying pathological mechanisms causing death and to ensure an adequate differential diagnosis.

From the identification of actionable molecular targets to the generation of faithful neuroblastoma patient-derived preclinical models.

BACKGROUND: Neuroblastoma (NB) represents the most frequent and aggressive form of extracranial solid tumor of infants. Although the overall survival of patients with NB has improved in the last years, more than 50% of high-risk patients still undergo a relapse. Thus, in the era of precision/personalized medicine, the need for high-risk NB patient-specific therapies is urgent. METHODS: Within the PeRsonalizEd Medicine (PREME) program, patient-derived NB tumors and bone marrow (BM)-infiltrating NB cells, derived from either iliac crests or tumor bone lesions, underwent to histological and to flow cytometry immunophenotyping, respectively. BM samples containing a NB cells infiltration from 1 to 50 percent, underwent to a subsequent NB cells enrichment using immune-magnetic manipulation. Then, NB samples were used for the identification of actionable targets and for the generation of 3D/tumor-spheres and Patient-Derived Xenografts (PDX) and Cell PDX (CPDX) preclinical models. RESULTS: Eighty-four percent of NB-patients showed potentially therapeutically targetable somatic alterations (including point mutations, copy number variations and mRNA over-expression). Sixty-six percent of samples showed alterations, graded as "very high priority", that are validated to be directly targetable by an approved drug or an investigational agent. A molecular targeted therapy was applied for four patients, while a genetic counseling was suggested to two patients having one pathogenic germline variant in known cancer predisposition genes. Out of eleven samples implanted in mice, five gave rise to (C)PDX, all preserved in a local PDX Bio-bank. Interestingly, comparing all molecular alterations and histological and immunophenotypic features among the original patient's tumors and PDX/CPDX up to second generation, a high grade of similarity was observed. Notably, also 3D models conserved immunophenotypic features and molecular alterations of the original tumors. CONCLUSIONS: PREME confirms the possibility of identifying targetable genomic alterations in NB, indeed, a molecular targeted therapy was applied to four NB patients. PREME paves the way to the creation of clinically relevant repositories of faithful patient-derived (C)PDX and 3D models, on which testing precision, NB standard-of-care and experimental medicines.

Serum-based ATR-FTIR spectroscopy combined with multivariate analysis for the diagnosis of pre-diabetes and diabetes.

Diabetes mellitus (DM) is a metabolic disease with an increasing prevalence that is causing worldwide concern. The pre-diabetes stage is the only reversible stage in the patho-physiological process towards DM. Due to the limitations of traditional methods, the diagnosis and detection of DM and pre-diabetes are complicated, expensive, and time-consuming. Therefore, it would be of great benefit to develop a simple, rapid and inexpensive diagnostic test. Herein, the infrared (IR) spectra of serum samples from 111 DM patients, 111 pre-diabetes patients and 333 healthy volunteers were collected using attenuated total reflection Fourier-transform IR (ATR-FTIR) spectroscopy and this was combined with the multivariate analysis of principal component analysis linear discriminant analysis (PCA-LDA) to develop a discriminant model to verify the diagnostic potential of this approach. The study found that the accuracy of the test model established by ATR-FTIR spectroscopy combined with PCA-LDA was 97%, and the sensitivity and specificity were 100% and 100% in the control group, 94% and 98% in the pre-diabetes group, and 91% and 98% in the DM group, respectively. This indicates that this method can effectively diagnose DM and pre-diabetes, which has far-reaching clinical significance.

Fast screening using attenuated total reflectance- fourier transform infrared (ATR-FTIR) spectroscopy of patients based on D-dimer threshold value.

Attenuated Total Reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy is an emerging technology in the medical field. Blood D-dimer was initially studied as a marker of the activation of coagulation and fibrinolysis. It is mainly used as a potential diagnosis screening test for pulmonary embolism or deep vein thrombosis but was recently associated with COVID-19 severity. This study aimed to evaluate the use of ATR-FTIR spectroscopy with machine learning to classify plasma D-dimer concentrations. The plasma ATR-FTIR spectra from 100 patients were studied through principal component analysis (PCA) and two supervised approaches: genetic algorithm with linear discriminant analysis (GA-LDA) and partial least squares with linear discriminant (PLS-DA). The spectra were truncated to the fingerprint region (1800-1000 cm-1). The GA-LDA method effectively classified patients according to D-dimer cutoff (≤0.5 µg/mL and >0.5 µg/mL) with 87.5 % specificity and 100 % sensitivity on the training set, and 85.7 % specificity, and 95.6 % sensitivity on the test set. Thus, we demonstrate that ATR-FTIR spectroscopy might be an important additional tool for classifying patients according to D-dimer values. ATR-FTIR spectral analyses associated with clinical evidence can contribute to a faster and more accurate medical diagnosis, reduce patient morbidity, and save resources and demand for professionals.

Exercise-Induced Muscle Damage after a High-Intensity Interval Exercise Session: Systematic Review.

High-intensity interval training (HIIT) is considered an effective method to improve fitness and health indicators, but its high-intensity exercises and the mechanical and metabolic stress generated during the session can lead to the occurrence of exercise-induced muscle damage. Therefore, this study aimed to describe, by means of a systematic review, the effects of a single HIIT session on exercise-induced muscle damage. A total of 43 studies were found in the Medline/PubMed Science Direct/Embase/Scielo/CINAHL/LILACS databases; however, after applying the exclusion criteria, only 15 articles were considered eligible for this review. The total sample was 315 participants. Among them, 77.2% were men, 13.3% were women and 9.5 uninformed. Their age ranged from 20.1 ± 2 to 47.8 ± 7.5 years. HIIT protocols included running with ergometers (n = 6), CrossFit-specific exercises (n = 2), running without ergometers (n = 3), swimming (n = 1), the Wingate test on stationary bicycles (n = 2), and cycling (n = 1). The most applied intensity controls were %vVO2max, "all out", MV, MAV, Vmax, and HRreserve%. The most used markers to evaluate muscle damage were creatine kinase, myoglobin, and lactate dehydrogenase. The time for muscle damage assessment ranged from immediately post exercise to seven days. HIIT protocols were able to promote changes in markers of exercise-induced muscle damage, evidenced by increases in CK, Mb, LDH, AST, ALT, pain, and muscle circumference observed mainly immediately and 24 h after the HIIT session.

The Role of Cyclin-Dependent Kinases (CDK) 4/6 in the Ovarian Tissue and the Possible Effects of Their Exogenous Inhibition.

The combination of cyclin-dependent kinase (CDK) 4/6 inhibitors with endocrine therapy is the standard treatment for patients with HR+/HER2- advanced breast cancer. Recently, this combination has also entered the early setting as an adjuvant treatment in patients with HR+/HER2- disease at a high risk of disease recurrence following (neo)adjuvant chemotherapy. Despite their current use in clinical practice, limited data on the potential gonadotoxicity of CDK4/6 inhibitors are available. Hence, fully informed treatment decision making by premenopausal patients concerned about the potential development of premature ovarian insufficiency and infertility with the proposed therapy remains difficult. The cell cycle progression of granulosa and cumulus cells is a critical process for ovarian function, especially for ensuring proper follicular growth and acquiring competence. Due to the pharmacological properties of CDK4/6 inhibitors, there could be a potentially negative impact on ovarian function and fertility in women of reproductive age. This review aims to summarize the role of the cyclin D-CDK4 and CDK6 complexes in the ovary and the potential impact of CDK4/6 inhibition on its physiological processes.

The fading guardian: clinical relevance of TP53 null mutation in high-grade serous ovarian cancers.

Background: we evaluated the concordance between immunohistochemical p53 staining and TP53 mutations in a series of HGSOC. Moreover, we searched for prognostic differences between p53 overexpression and null expression groups. Methods: patients affected by HGSOC were included. For each case p53 immunohistochemical staining and molecular assay (Sanger sequencing) were performed. Kaplan-Meier survival analyses were undertaken to determine whether the type of TP53 mutation, or p53 staining pattern influenced overall survival (OS) and progression free survival (PFS). Results: 34 HGSOC were considered. All cases with a null immunohistochemical p53 expression (n=16) showed TP53 mutations (n=9 nonsense, n=4 in-frame deletion, n=2 splice, n=1 in-frame insertion). 16 out of 18 cases with p53 overexpression showed TP53 missense mutation. Follow up data were available for 33 out of 34 cases (median follow up time 15 month). We observed a significant reduction of OS in p53 null group [HR = 3.64, 95% CI 1.01-13.16]. Conclusion: immunohistochemical assay is a reliable surrogate for TP53 mutations in most cases. Despite the small cohort and the limited median follow up, we can infer that HGSOC harboring p53 null mutations are a more aggressive subgroup.

Blood Flow Restriction Attenuates Muscle Damage in Resistance Exercise Performed Until Concentric Muscle Failure.

The present study aimed to evaluate whether blood flow restriction (BFR) can prevent exercise-induced muscle damage in resistance exercise (RE) performed until concentric muscle failure (CMF). Twenty healthy volunteers (25 ± 4 years, 80.4 ± 11.8 kg, 175 ± 8 cm) performed three sets of unilateral biceps curl exercise (40% of 1RM) with (RE + BFR) and without (RE) BFR until CMF. A third condition was to perform the same number of repetitions as RE + BFR without using BFR (matched). Performing fewer repetitions, RE + BFR caused muscle fatigue post-exercise as high as that caused by RE. In addition, the range of motion, upper arm circumference, pressure pain threshold, and maximal voluntary contraction were immediately affected by our exercise protocol with BFR, returning rapidly to basal values within 24 h, while in RE, muscle damage markers remained elevated until 48 h post-exercise. The same results were observed concerning serum creatine kinase and lactate dehydrogenase activity. Thus, BFR + RE performed until CMF attenuated muscle damage following similar metabolic stress to RE alone performed until CMF, with less work volume.

Pyrosequencing Assay for BRCA1 Methylation Analysis: Results from a Cross-Validation Study.

Epithelial ovarian cancers (EOCs) harboring germline or somatic pathogenic variants in BRCA1 and BRCA2 genes show sensitivity to poly(ADP-ribose) polymerase inhibition. It has been suggested that BRCA1 promoter methylation is perhaps a better determinant of therapy response, because of its intrinsic dynamic feature, with respect to genomic scars or gene mutation. Conflicting evidence was reported so far, and the lack of a validated assay to measure promoter methylation was considered a main confounding factor in data interpretation. To contribute to the validation process of a pyrosequencing assay for BRCA1 promoter methylation, 109 EOCs from two Italian centers were reciprocally blindly investigated. By comparing two different pyrosequencing assays, addressing a partially overlapping region of BRCA1 promoter, an almost complete concordance of results was obtained. Moreover, the clinical relevance of this approach was also supported by the finding of BRCA1 transcript down-regulation in BRCA1-methylated EOCs. These findings could lead to the development of a simple and cheap pyrosequencing assay for diagnostics, easily applicable to formalin-fixed, paraffin-embedded tissues. This technique may be implemented in routine clinical practice in the near future to identify EOCs sensitive to poly(ADP-ribose) polymerase inhibitor therapy, thus increasing the subset of women affected by EOCs who could benefit from such treatment.

Potential Role of Fourier Transform Infrared Spectroscopy as a Screening Approach for Breast Cancer.

Breast cancer is a heterogeneous disease, and its spread involves a succession of clinical and pathological stages. Screening is predominantly based on mammography, which has critical limitations related to the effectiveness and production of false-positive or false-negative results, generating discomfort and low adherence. In this context, infrared with attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy emerges as a non-destructive sample tool, which is non-invasive, label-free, has a low operating-cost, and requires only a small amount of sample, including liquid plasma samples. We sought to evaluate the clinical applicability of ATR FT-IR in breast cancer screening. ATR FT-IR spectroscopy through its highest potential spectral biomarker could distinguish, by liquid plasma biopsy, breast cancer patients and healthy controls, obtaining a sensitivity of 97%, specificity of 93%, a receiver operating characteristic ROC curve of 97%, and a prediction accuracy of 94%. The main variance between the groups was mainly in the band 1511 cm-1 of the control group, 1502 and 1515 cm-1 of the cancer group, which are the peaks of the bands referring to proteins and amide II. ATR FT-IR spectroscopy has demonstrated to be a promising tool for breast cancer screening, given its time efficiency, cost of approach, and its high ability to distinguish between the liquid plasma samples of breast cancer patients and healthy controls.

Active breaks: a strategy to counteract sedentary behaviors for Health Promoting Schools. A discussion on their implementation in Italy.

Abstract: School Active Breaks are short bouts of physical activity (5-15 minutes) conducted by appropriately trained teachers and delivered during or between curricular lessons. They are a good strategy to counteract sedentary behaviors, and a growing body of evidence shows that they can represent also a tool to promote and improve health, school wellbeing and academic achievements. On 19 February 2022, the Working Group on Movement Sciences for Health of the Italian Society of Hygiene, Preventive Medicine and Public Health organized an Awareness Day on the effectiveness, usefulness and feasibility of School Active Breaks, opened to teachers, educators, school leaders, pediatricians, personnel from Departments of Prevention and Public Health and Health Policy-makers. During the event, the testimonies about the experiences already carried out in Italy showed that School Active Breaks are an effective intervention that each school can easily include in its educational offer and apply in any context.

MALDI(+) FT-ICR Mass Spectrometry (MS) Combined with Machine Learning toward Saliva-Based Diagnostic Screening for COVID-19.

Rapid identification of existing respiratory viruses in biological samples is of utmost importance in strategies to combat pandemics. Inputting MALDI FT-ICR MS (matrix-assisted laser desorption/ionization Fourier-transform ion cyclotron resonance mass spectrometry) data output into machine learning algorithms could hold promise in classifying positive samples for SARS-CoV-2. This study aimed to develop a fast and effective methodology to perform saliva-based screening of patients with suspected COVID-19, using the MALDI FT-ICR MS technique with a support vector machine (SVM). In the method optimization, the best sample preparation was obtained with the digestion of saliva in 10 µL of trypsin for 2 h and the MALDI analysis, which presented a satisfactory resolution for the analysis with 1 M. SVM models were created with data from the analysis of 97 samples that were designated as SARS-CoV-2 positives versus 52 negatives, confirmed by RT-PCR tests. SVM1 and SVM2 models showed the best results. The calibration group obtained 100% accuracy, and the test group 95.6% (SVM1) and 86.7% (SVM2). SVM1 selected 780 variables and has a false negative rate (FNR) of 0%, while SVM2 selected only two variables with a FNR of 3%. The proposed methodology suggests a promising tool to aid screening for COVID-19.

Phenotypes of prediabetes and metabolic risk in Caucasian youths with overweight or obesity.

PURPOSE: To assess the prevalence of pre-diabetes phenotypes, i.e., impaired fasting glucose (IFG), impaired glucose tolerance (IGT), increased HbA1c (IA1c), and their association with metabolic profile and atherogenic lipid profile in youths with overweight/obesity (OW/OB). METHODS: This cross-sectional study analyzed data of 1549 youths (5-18 years) with OW/OB followed in nine Italian centers between 2016 and 2020. Fasting and post-load measurements of glucose, insulin, and HbA1c were available. Insulin resistance (IR) was estimated by HOMA-IR and insulin sensitivity (IS) by reciprocal of fasting insulin. The atherogenic lipid profile was assessed by triglycerides-to-HDL ratio or cholesterol-to-HDL ratio. Insulinogenic index was available in 939 youths, in whom the disposition index was calculated. RESULTS: The prevalence of overall pre-diabetes, IFG, IGT and IA1c was 27.6%, 10.2%, 8% and 16.3%, respectively. Analyzing each isolated phenotype, IGT exhibited two- to three-fold higher odds ratio of family history of diabetes, and worse metabolic and atherogenic lipid profile vs normoglycemic youths; IFG was associated only with IR, while IA1c showed a metabolic and atherogenic lipid profile intermediate between IGT and IFG. CONCLUSION: Prevalence of pre-diabetes was high and IA1c was the most prevalent phenotype in Italian youths with OW/OB. The IGT phenotype showed the worst metabolic and atherogenic lipid profile, followed by IA1c. More studies are needed to assess whether HbA1c may help improving the prediction of diabetes.

Screening for hypertension in young people with obesity: Feasibility in the real life.

BACKGROUND AND AIM: Screening for pediatric hypertension (HTN) is based on several measurements of blood pressure (BP) in different visits. We aimed to assess its feasibility in outpatient youths with overweight/obesity (OW/OB) in terms of adherence to two-repeated measurements of BP and to show the features of youths who missed the follow-up and the predictive role of clinical and/or anamnestic features on confirmed HTN. METHODS AND RESULTS: Six hundred, eighty-eight youths (9-17 years) with OW/OB, consecutively recruited, underwent a first measurement of BP. Those exhibiting BP levels within the hypertensive range were invited to repeat a second measurement within 1-2 weeks. Confirmed HTN was diagnosed when BP in the hypertensive range was confirmed at the second measurement. At entry, 174 youths (25.1%) were classified as hypertensive. At the second visit, 66 youths (37.9%) were lost to follow-up. In the remaining 108 participants, HTN was confirmed in 59, so that the prevalence of confirmed HTN was 9.5% in the overall sample; it was higher in adolescents than children (15.9% vs 6.8%, P = 0.001). HTN at first visit showed the best sensitivity (100%) and a good specificity (91%) for confirmed HTN. The association of HTN at first visit plus familial HTN showed high specificity (98%) and positive predictive value of 70%. CONCLUSION: The high drop-out rate confirms the real difficulty to obtain a complete diagnostic follow up in the obese population. Information about family history of HTN may assist pediatricians in identifying those children who are at higher risk of confirmed HTN.

In Vitro Evolution Reveals Noncationic Protein-RNA Interaction Mediated by Metal Ions.

RNA-peptide/protein interactions have been of utmost importance to life since its earliest forms, reaching even before the last universal common ancestor (LUCA). However, the ancient molecular mechanisms behind this key biological interaction remain enigmatic because extant RNA-protein interactions rely heavily on positively charged and aromatic amino acids that were absent (or heavily under-represented) in the early pre-LUCA evolutionary period. Here, an RNA-binding variant of the ribosomal uL11 C-terminal domain was selected from an approximately 1010 library of partially randomized sequences, all composed of ten prebiotically plausible canonical amino acids. The selected variant binds to the cognate RNA with a similar overall affinity although it is less structured in the unbound form than the wild-type protein domain. The variant complex association and dissociation are both slower than for the wild-type, implying different mechanistic processes involved. The profile of the wild-type and mutant complex stabilities along with molecular dynamics simulations uncovers qualitative differences in the interaction modes. In the absence of positively charged and aromatic residues, the mutant uL11 domain uses ion bridging (K+/Mg2+) interactions between the RNA sugar-phosphate backbone and glutamic acid residues as an alternative source of stabilization. This study presents experimental support to provide a new perspective on how early protein-RNA interactions evolved, where the lack of aromatic/basic residues may have been compensated by acidic residues plus metal ions.

Noninvasive Diagnostic for COVID-19 from Saliva Biofluid via FTIR Spectroscopy and Multivariate Analysis.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the worst global health crisis in living memory. The reverse transcription polymerase chain reaction (RT-qPCR) is considered the gold standard diagnostic method, but it exhibits limitations in the face of enormous demands. We evaluated a mid-infrared (MIR) data set of 237 saliva samples obtained from symptomatic patients (138 COVID-19 infections diagnosed via RT-qPCR). MIR spectra were evaluated via unsupervised random forest (URF) and classification models. Linear discriminant analysis (LDA) was applied following the genetic algorithm (GA-LDA), successive projection algorithm (SPA-LDA), partial least squares (PLS-DA), and a combination of dimension reduction and variable selection methods by particle swarm optimization (PSO-PLS-DA). Additionally, a consensus class was used. URF models can identify structures even in highly complex data. Individual models performed well, but the consensus class improved the validation performance to 85% accuracy, 93% sensitivity, 83% specificity, and a Matthew's correlation coefficient value of 0.69, with information at different spectral regions. Therefore, through this unsupervised and supervised framework methodology, it is possible to better highlight the spectral regions associated with positive samples, including lipid (∼1700 cm-1), protein (∼1400 cm-1), and nucleic acid (∼1200-950 cm-1) regions. This methodology presents an important tool for a fast, noninvasive diagnostic technique, reducing costs and allowing for risk reduction strategies.

Roux-en-Y Gastric Bypass and Sleeve Gastrectomy Differently Affect Oxidative Damage Markers and their Correlations with Body Parameters.

BACKGROUND: Bariatric surgery improves oxidative damage, but little is known about the differences between Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG). This study compared changes in lipid and protein oxidative damage markers and their correlations with body parameters of patients before and after RYGB or SG. METHODS: Body mass index (BMI), bioimpedance parameters, and biochemical parameters including lipid and protein oxidative damage markers were evaluated before and 6 months after surgery. Data were analyzed by t test or Mann-Whitney rank sum test and Spearman's correlation coefficient between oxidative damage and other parameters. RESULTS: Twenty-five patients were submitted to RYGB and 14 to SG. There was a significant decrease of BMI, fat mass, fat-free mass, phase angle, serum total protein, transthyretin, and C-reactive protein in both groups (p < 0.05). Serum thiobarbituric acid reactive substances (TBARS), advanced oxidation protein products (AOPP), and serum lipids (p < 0.05) were significantly decreased in the RYGB group. TBARS levels were significantly correlated with serum total cholesterol (r = 0.468), LDL (r = 0.439), BMI (r = 0.424), and fat mass (r = 0.40) (p < 0.05). In the SG group, AOPP levels were significantly correlated with serum C-reactive protein (baseline: r = 0.53, 6 months: r = 0.64) (p < 0.05). Alterations in these levels were negatively correlated with changes in BIA parameters [resistance (r = -0.574), reactance (r = -0.736), and phase angle (r = 0.549)] (p < 0.05). CONCLUSIONS: RYGB seems to be better in attenuating oxidative damage after 6 months. The BMI reduction in the RYGB group suggests a concomitant decrease of lipid oxidative damage. In the SG group, changes in BIA parameters were inversely correlated with protein oxidative damage.

SIRT6 enhances oxidative phosphorylation in breast cancer and promotes mammary tumorigenesis in mice.

BACKGROUND: Sirtuin 6 (SIRT6) is a NAD+-dependent deacetylase with key roles in cell metabolism. High SIRT6 expression is associated with adverse prognosis in breast cancer (BC) patients. However, the mechanisms through which SIRT6 exerts its pro-oncogenic effects in BC remain unclear. Here, we sought to define the role of SIRT6 in BC cell metabolism and in mouse polyoma middle T antigen (PyMT)-driven mammary tumors. METHODS: We evaluated the effect of a heterozygous deletion of Sirt6 on tumor latency and survival of mouse mammary tumor virus (MMTV)-PyMT mice. The effect of SIRT6 silencing on human BC cell growth was assessed in MDA-MB-231 xenografts. We also analyzed the effect of Sirt6 heterozygous deletion, of SIRT6 silencing, and of the overexpression of either wild-type (WT) or catalytically inactive (H133Y) SIRT6 on BC cell pyruvate dehydrogenase (PDH) expression and activity and oxidative phosphorylation (OXPHOS), including respiratory complex activity, ATP/AMP ratio, AMPK activation, and intracellular calcium concentration. RESULTS: The heterozygous Sirt6 deletion extended tumor latency and mouse survival in the MMTV-PyMT mouse BC model, while SIRT6 silencing slowed the growth of MDA-MB-231 BC cell xenografts. WT, but not catalytically inactive, SIRT6 enhanced PDH expression and activity, OXPHOS, and ATP/AMP ratio in MDA-MB-231 and MCF7 BC cells. Opposite effects were obtained by SIRT6 silencing, which also blunted the expression of genes encoding for respiratory chain proteins, such as UQCRFS1, COX5B, NDUFB8, and UQCRC2, and increased AMPK activation in BC cells. In addition, SIRT6 overexpression increased, while SIRT6 silencing reduced, intracellular calcium concentration in MDA-MB-231 cells. Consistent with these findings, the heterozygous Sirt6 deletion reduced the expression of OXPHOS-related genes, the activity of respiratory complexes, and the ATP/AMP ratio in tumors isolated from MMTV-PyMT mice. CONCLUSIONS: Via its enzymatic activity, SIRT6 enhances PDH expression and activity, OXPHOS, ATP/AMP ratio, and intracellular calcium concentration, while reducing AMPK activation, in BC cells. Thus, overall, SIRT6 inhibition appears as a viable strategy for preventing or treating BC.