Structural basis for reduced ribosomal A-site fidelity in response to P-site codon-anticodon mismatches.

Rapid and accurate translation is essential in all organisms to produce properly folded and functional proteins. mRNA codons that define the protein-coding sequences are decoded by tRNAs on the ribosome in the aminoacyl (A) binding site. The mRNA codon and the tRNA anticodon interaction is extensively monitored by the ribosome to ensure accuracy in tRNA selection. While other polymerases that synthesize DNA and RNA can correct for misincorporations, the ribosome is unable to correct mistakes. Instead, when a misincorporation occurs, the mismatched tRNA-mRNA pair moves to the peptidyl (P) site and, from this location, causes a reduction in the fidelity at the A site, triggering post-peptidyl transfer quality control. This reduced fidelity allows for additional incorrect tRNAs to be accepted and for release factor 2 (RF2) to recognize sense codons, leading to hydrolysis of the aberrant peptide. Here, we present crystal structures of the ribosome containing a tRNALys in the P site with a U•U mismatch with the mRNA codon. We find that when the mismatch occurs in the second position of the P-site codon-anticodon interaction, the first nucleotide of the A-site codon flips from the mRNA path to engage highly conserved 16S rRNA nucleotide A1493 in the decoding center. We propose that this mRNA nucleotide mispositioning leads to reduced fidelity at the A site. Further, this state may provide an opportunity for RF2 to initiate premature termination before erroneous nascent chains disrupt the cellular proteome.

Functional activation of pyruvate dehydrogenase in human brain using hyperpolarized [1-13 C]pyruvate.

PURPOSE: Pyruvate, produced from either glucose, glycogen, or lactate, is the dominant precursor of cerebral oxidative metabolism. Pyruvate dehydrogenase (PDH) flux is a direct measure of cerebral mitochondrial function and metabolism. Detection of [13 C]bicarbonate in the brain from hyperpolarized [1-13 C]pyruvate using carbon-13 (13 C) MRI provides a unique opportunity for assessing PDH flux in vivo. This study is to assess changes in cerebral PDH flux in response to visual stimuli using in vivo 13 C MRS with hyperpolarized [1-13 C]pyruvate. METHODS: From seven sedentary adults in good general health, time-resolved [13 C]bicarbonate production was measured in the brain using 90° flip angles with minimal perturbation of its precursors, [1-13 C]pyruvate and [1-13 C]lactate, to test the hypothesis that the appearance of [13 C]bicarbonate signals in the brain reflects the metabolic changes associated with neuronal activation. With a separate group of healthy participants (n = 3), the likelihood of the bolus-injected [1-13 C]pyruvate being converted to [1-13 C]lactate prior to decarboxylation was investigated by measuring [13 C]bicarbonate production with and without [1-13 C]lactate saturation. RESULTS: In the course of visual stimulation, the measured [13 C]bicarbonate signal normalized to the total 13 C signal in the visual cortex increased by 17.1% ± 15.9% (p = 0.017), whereas no significant change was detected in [1-13 C]lactate. Proton BOLD fMRI confirmed the regional activation in the visual cortex with the stimuli. Lactate saturation decreased bicarbonate-to-pyruvate ratio by 44.4% ± 9.3% (p < 0.01). CONCLUSION: We demonstrated the utility of 13 C MRS with hyperpolarized [1-13 C]pyruvate for assessing the activation of cerebral PDH flux via the detection of [13 C]bicarbonate production.

Breast Conservation Project: Clinical Outcomes of Extreme Oncoplastic Breast-Conserving Therapy Versus Mastectomy for Large and Multiple Lesions.

INTRODUCTION: Patients with multiple or large malignant breast lesions are classically considered mastectomy candidates, but extreme oncoplastic breast-conservation surgery (eOBCS) has become an alternative approach. There is a paucity of outcomes data comparing eOBCS with mastectomy. METHODS: We reviewed our prospectively maintained, single-institution database. We included patients with non-metastatic breast cancer with multiple ipsilateral or single large (≥ 5 cm) malignant breast lesions identified preoperatively who underwent either eOBCS or mastectomy. Patient demographics, clinicopathologic features, and surgical, oncologic, and cosmetic outcomes were evaluated. RESULTS: Seventy-six (88%) patients underwent eOBCS and 10 (12%) underwent mastectomy. Median follow-up was 24.8 months. Mastectomy patients had larger lesions than eOBCS patients (median 70 mm vs. 32.5 mm; p = 0.06). Six (60%) index mastectomy patients underwent at least one additional surgery. For eOBCS patients, 34 (44%) required re-excision, 7 of whom underwent more than one subsequent surgery to obtain negative margins, and 6 (7.9%) ultimately underwent mastectomy. For patients undergoing additional surgery (n = 40), median time between index and final operation was 315 days for mastectomy versus 21 days for eOBCS patients (p < 0.001). Mastectomy patients more frequently experienced complications (p = 0.001) and underwent cosmetic revision (p < 0.001). There was no difference in cosmetic scores, and eOBCS patients reported less pain (p = 0.009). There were two local and three distant recurrences in the eOBCS cohort and one distant recurrence in the mastectomy group. CONCLUSION: Breast conservation was attainable in over 90% of eOBCS patients. Increased postoperative complications and discomfort and longer duration of surgical treatment in mastectomy patients without oncologic superiority should drive informed patient discussions.

Comparing Costs: Does Extreme Oncoplastic Breast-Conserving Surgery Confer a Cost Benefit When Compared with Mastectomy and Reconstruction?

INTRODUCTION: Extreme oncoplastic breast-conserving surgery (eOBCS) describes the application of OBCS to patients who would otherwise need a mastectomy, and its safety has been previously described. OBJECTIVE: We aimed to compare the costs of eOBCS and mastectomy. METHODS: We reviewed our institutional database to identify breast cancer patients treated surgically from 2018 to 2023. We included patients with a large disease span (≥5 cm) and multifocal/multicentric disease. Patients were grouped by their surgical approach, i.e. eOBCS or mastectomy. The direct costs of care were determined and compared; however, indirect costs were not included. RESULTS: Eighty-six patients met the inclusion criteria, 10 (11.6%) of whom underwent mastectomy and 76 (88.4%) who underwent eOBCS. Six mastectomy patients (60%) had reconstruction and 6 (60%) underwent external beam radiation therapy (EBRT). Reconstructions were completed in a staged fashion, and the mean cost of the index operation (mastectomy and tissue expander) was $17,816. These patients had one to three subsequent surgeries to complete their reconstruction, at a mean cost of $45,904. The mean cost of EBRT was $5542. Thirty-four eOBCS patients (44.7%) underwent 44 margin re-excisions, including 6 (7.9%) who underwent mastectomy. Sixty (78.9%) of the eOBCS patients had EBRT. The mean cost of their index operation was $6345; the mean cost of a re-excision was $3615; the mean cost of their mastectomies with reconstruction was $49,400; and the mean cost of EBRT was $6807. The cost of care for eOBCS patients remained lower than that for mastectomy patients, i.e. $17,318 versus $57,416. CONCLUSION: eOBCS is associated with a lower cost than mastectomy and had a low conversion rate to mastectomy.

Medical Mistrust Among Black Patients with Serious Illness: A Mixed Methods Study.

BACKGROUND: Medical mistrust among Black patients has been used to explain the existence of well-documented racial inequities at the end of life that negatively impact this group. However, there are few studies that describe patient perspectives around the impact of racism and discriminatory experiences on mistrust within the context of serious illness. OBJECTIVE: To better characterize experiences of racism and discrimination among patients with serious illness and its association with medical mistrust. PARTICIPANTS: Seventy-two Black participants with serious illness hospitalized at an academic county hospital. APPROACH: This is a convergent mixed methods study using data from participant-completed surveys and existing semi-structured interviews eliciting participants' perspectives around their experiences with medical racism, communication, and decision-making. MAIN MEASURES: The experience of medical racism and its association with Group-Based Medical Mistrust (GBMM) scale scores, a validated measure of medical mistrust. KEY RESULTS: Of the 72 Black participants, 35% participated in interviews. Participants were mostly men who had significant socioeconomic disadvantage, including low levels of wealth, income, and educational attainment. There were reported high levels of race-based mistrust in the overall GBMM scale score (mean [SD], 36.6 [9.9]), as well as high scores within the suspicion (14.2 [5.0]), group disparities in healthcare (9.9 [2.8]), and lack of support (9.1 [2.7]) subscales. Three qualitative themes aligned with the GBMM subscales. Participants expressed skepticism of healthcare workers (HCWs) and modern medicine, recounted personal experiences of discrimination in the medical setting, and were frustrated with poor communication from HCWs. CONCLUSIONS: This study found high levels of mistrust among Black patients with serious illness. Suspicion of HCWs, disparities in healthcare by race, and a lack of support from HCWs were overarching themes that influenced medical mistrust. Critical, race-conscious approaches are needed to create strategies and frameworks to improve the trustworthiness of healthcare institutions and workers.

Acceptability of a Randomized Trial of Anti-depressant Medication or Interpersonal Therapy for Treatment of Perinatal Depression in Women with HIV.

Postpartum depression (PPD) affects nearly 20% of postpartum women in Sub-Saharan Africa (SSA), where HIV prevalence is high. Depression is associated with worse HIV outcomes in non-pregnant adults and mental health disorders may worsen HIV outcomes for postpartum women and their infants. PPD is effectively treated with psychosocial or pharmacologic interventions; however, few studies have evaluated the acceptability of treatment modalities in SSA. We analyzed interviews with 23 postpartum women with HIV to assess the acceptability of two depression treatments provided in the context of a randomized trial. Most participants expressed acceptability of treatment randomization and study visit procedures. Participants shared perceptions of high treatment efficacy of their assigned intervention. They reported ongoing HIV and mental health stigma in their communities and emphasized the importance of social support from clinic staff. Our findings suggest a full-scale trial of PPD treatment will be acceptable among women with HIV in Zambia.

Simultaneous Symmetry Procedure in Patients Undergoing Oncoplastic Breast-Conserving Surgery: An Evaluation of Patient Desire and Revision Rates.

INTRODUCTION: In the era of oncoplastic breast conserving-surgery (OBCS), cosmetic outcomes and the desire for symmetry have become essential elements of the surgical management of breast cancer (BC). The timing of contralateral symmetry procedures remains a controversial topic. Simultaneous symmetry procedures (SSP) in OBCS have not been routinely offered due to the perceived risk of delayed asymmetry, potentially increasing the need for delayed cosmetic revision. This study evaluates the rate of revision after SSP in patients undergoing OBCS. METHODS: We reviewed our institutional prospectively maintained database identifying all BC patients treated surgically since our introduction of oncoplastic surgery in 2018. We routinely offer SSP when appropriate. Descriptive statistics evaluated oncoplastic surgical techniques, SSP offerings and procedures, perioperative complications, and revision rates after treatment completion. RESULTS: Between 2018 and 2022, 485 breast cancer patients underwent partial mastectomy, and 396 (82%) underwent OBCS. Of the 313 patients offered SSP, 272 (87%) accepted. The margin reexcision rate of this cohort was 20%. Of the 272 patients with SSP, 152 (56%) underwent intraoperative radiation therapy (IORT), and 105 (39%) had adjuvant external beam radiation therapy. Three patients (1%) experienced complications involving the symmetry side. No patients with complications experienced a delay in adjuvant therapies or requested cosmetic revisions. Three patients (1%) desired surgical revisions due to asymmetry. CONCLUSIONS: Symmetry procedures at the time of OBCS are widely accepted by patients and rarely require delayed cosmetic revision. Simultaneous symmetry procedures should be routinely discussed with patients during the surgical planning of OBCS.

A Look at the Other Side: High-Risk Lesions and Occult Contralateral Malignancy in Symmetry Procedures for Patients Undergoing Oncoplastic Breast-Conserving Surgery.

BACKGROUND: The incidence of occult breast cancer among patients undergoing reduction mammoplasty or risk-reducing mastectomies ranges from 1% to approximately 10%, respectively. Identification of incidental cancer often mandates subsequent mastectomy due to ambiguous margins. This study aimed to determine the incidence of contralateral malignancy among patients undergoing oncoplastic breast-conserving surgery (OBCS) with concurrent symmetry procedures. METHODS: The authors reviewed their prospectively maintained institutional database of patients with unilateral breast cancer who underwent OBCS. Patients who underwent excisional biopsy on the contralateral breast were analyzed separately. Patient demographics, pathologic features, and subsequent disease management were evaluated. RESULTS: Between March 2018 and July 2022, 289 patients underwent OBCS with a symmetry procedure, and 100 patients yielded contralateral breast tissue specimens. For 14 patients, a planned excisional biopsy was performed with their symmetry procedure, and five lesions (36%) were found to be malignant. Of the remaining 86 patients, 92% underwent preoperative breast magnetic resonance imaging (MRI). Four patients (4.7%) had occult malignancies identified on the contralateral breast pathology; three patients with ductal carcinoma in situ and one patient with invasive lobular carcinoma. Three patients had undergone preoperative MRI without suspicious findings. No patients required mastectomy for treatment of the contralateral breast cancer. CONCLUSION: The incidence of occult malignancy among OBCS symmetry procedures approaches 5%. The final pathology of excisional biopsies had a higher upgrade rate than previously reported. All identified malignancies were early-stage disease. The higher incidence of occult breast cancer in this population warrants the routine orientation of all specimens, which allows patients with incidental early-stage cancer the option of breast preservation.

Physician Perspectives on Responding to Clinician-Perpetuated Interpersonal Racism Against Black Patients with Serious Illness.

BACKGROUND: Racism negatively affects clinical outcomes in Black patients, but uncertainty remains among physicians regarding how to address interpersonal anti-Black racism incidences involving them to facilitate racial healing and promote accountability. OBJECTIVE: Elicit physician perspectives on addressing concerns from Black patients about interpersonal racism involving them or their team. PARTICIPANTS: Twenty-one physician subspecialists at an urban academic medical center. APPROACH: We conducted one-on-one semi-structured interviews to help inform the development of a clinician-facing component of a program to address the distress of racism experienced by Black patients with serious illness. We asked clinicians to describe experiences discussing racism with patients and identify additional resources to support these conversations. MAIN MEASURES: Physician perspectives, including barriers and facilitators, to promote racial healing and clinician accountability when discussing clinician-perpetuated interpersonal racism with Black patients. KEY RESULTS: Of the 21 participating physicians, 67% were women with a mean age of 44.2 years and mean of 10.8 years of experience as an attending physician. Four identified as Asian, three identified as Black, and 14 identified as White. Participants largely felt unprepared to discuss racism with their patients, especially if the harm was caused by them or their team. Participants felt patients should be given tools to discuss concerns about racism with their clinicians, but worried about adding additional burdens to Black patients to call out racism. Participants believed programs and processes with both patient- and clinicians-facing components had the potential to empower patients while providing resources and tools for clinicians to engage in these highly sensitive discussions without perpetuating more harm. CONCLUSIONS: Addressing and improving communication about interpersonal racism in clinical settings are challenging. Dual-facing programs involving patients and clinicians may help provide additional resources to address experiences of interpersonal racism and hold clinicians accountable.

Extracorporeal Membrane Oxygenation during Respiratory Pandemics: Past, Present, and Future.

The role of extracorporeal membrane oxygenation (ECMO) in the management of severe acute respiratory failure, including acute respiratory distress syndrome, has become better defined in recent years in light of emerging high-quality evidence and technological advances. Use of ECMO has consequently increased throughout many parts of the world. The coronavirus disease (COVID-19) pandemic, however, has highlighted deficiencies in organizational capacity, research capability, knowledge sharing, and resource use. Although governments, medical societies, hospital systems, and clinicians were collectively unprepared for the scope of this pandemic, the use of ECMO, a highly resource-intensive and specialized form of life support, presented specific logistical and ethical challenges. As the pandemic has evolved, there has been greater collaboration in the use of ECMO across centers and regions, together with more robust data reporting through international registries and observational studies. Nevertheless, centralization of ECMO capacity is lacking in many regions of the world, and equitable use of ECMO resources remains uneven. There are no widely available mechanisms to conduct large-scale, rigorous clinical trials in real time. In this critical care review, we outline lessons learned during COVID-19 and prior respiratory pandemics in which ECMO was used, and we describe how we might apply these lessons going forward, both during the ongoing COVID-19 pandemic and in the future.

Intervention to Promote Communication About Goals of Care for Hospitalized Patients With Serious Illness: A Randomized Clinical Trial.

Importance: Discussions about goals of care are important for high-quality palliative care yet are often lacking for hospitalized older patients with serious illness. Objective: To evaluate a communication-priming intervention to promote goals-of-care discussions between clinicians and hospitalized older patients with serious illness. Design, Setting, and Participants: A pragmatic, randomized clinical trial of a clinician-facing communication-priming intervention vs usual care was conducted at 3 US hospitals within 1 health care system, including a university, county, and community hospital. Eligible hospitalized patients were aged 55 years or older with any of the chronic illnesses used by the Dartmouth Atlas project to study end-of-life care or were aged 80 years or older. Patients with documented goals-of-care discussions or a palliative care consultation between hospital admission and eligibility screening were excluded. Randomization occurred between April 2020 and March 2021 and was stratified by study site and history of dementia. Intervention: Physicians and advance practice clinicians who were treating the patients randomized to the intervention received a 1-page, patient-specific intervention (Jumpstart Guide) to prompt and guide goals-of-care discussions. Main Outcomes and Measures: The primary outcome was the proportion of patients with electronic health record-documented goals-of-care discussions within 30 days. There was also an evaluation of whether the effect of the intervention varied by age, sex, history of dementia, minoritized race or ethnicity, or study site. Results: Of 3918 patients screened, 2512 were enrolled (mean age, 71.7 [SD, 10.8] years and 42% were women) and randomized (1255 to the intervention group and 1257 to the usual care group). The patients were American Indian or Alaska Native (1.8%), Asian (12%), Black (13%), Hispanic (6%), Native Hawaiian or Pacific Islander (0.5%), non-Hispanic (93%), and White (70%). The proportion of patients with electronic health record-documented goals-of-care discussions within 30 days was 34.5% (433 of 1255 patients) in the intervention group vs 30.4% (382 of 1257 patients) in the usual care group (hospital- and dementia-adjusted difference, 4.1% [95% CI, 0.4% to 7.8%]). The analyses of the treatment effect modifiers suggested that the intervention had a larger effect size among patients with minoritized race or ethnicity. Among 803 patients with minoritized race or ethnicity, the hospital- and dementia-adjusted proportion with goals-of-care discussions was 10.2% (95% CI, 4.0% to 16.5%) higher in the intervention group than in the usual care group. Among 1641 non-Hispanic White patients, the adjusted proportion with goals-of-care discussions was 1.6% (95% CI, -3.0% to 6.2%) higher in the intervention group than in the usual care group. There was no evidence of differential treatment effects of the intervention on the primary outcome by age, sex, history of dementia, or study site. Conclusions and Relevance: Among hospitalized older adults with serious illness, a pragmatic clinician-facing communication-priming intervention significantly improved documentation of goals-of-care discussions in the electronic health record, with a greater effect size in racially or ethnically minoritized patients. Trial Registration: ClinicalTrials.gov Identifier: NCT04281784.

Race-conscious serious illness communication: An interpersonal tool to dismantle racism in practice and research.

BACKGROUND: Racism significantly contributes to inequitable care quality and outcomes for people of color with serious illness, their families, and their communities. Clinicians use serious illness communication (SIC) to foster trust, elicit patients' needs and values, and deliver goal-concordant services. Current SIC tools do not actively guide users to incorporate patients' experiences with racism into care. OBJECTIVES: 1) To explicitly address racism during SIC in the context of the patient's lived experience and 2) to provide race-conscious SIC recommendations for clinicians and researchers. METHODS: Applying the conceptual elements of Public Health Critical Race Praxis to SIC practice and research through reflection on inclusive SIC approaches and a composite case. RESULTS: Patients' historical and ongoing narratives of racism must be intentionally welcomed in physically and psychologically safe environments by leveraging empathic communication opportunities, forging antiracist palliative care practices, removing interpersonal barriers to promote transparent patient-clinician relationships, and strengthening organizational commitments to strategically dismantle racism. Race-conscious SIC communication strategies, skills, and examples of talking points are provided. DISCUSSION: Race-conscious SIC practices may assist to acknowledge racial dynamics within the patient-clinician encounter. Furthermore, race-conscious SIC may help to mitigate implicit and explicit bias in clinical practices and the exclusionary research cultures that guide them.

Genus-wide analysis of Fusarium polyketide synthases reveals broad chemical potential.

The genus Fusarium includes pathogens of global concern to animal and plant health. Natural products (NPs) synthesized by Fusarium can contribute to pathogenesis or competitiveness of the fungus in the environment and to animal diseases, including cancer and neural tube defects. Polyketide synthases (PKSs) are a family of large, multi-domain enzymes that are required for synthesis of most fungal NPs. To gain insight into the NP potential of Fusarium, we retrieved 2974 PKS gene sequences from the genomes of 206 Fusarium species. Phylogenetic analysis resolved these PKSs, along with 118 previously described PKSs from other fungi, into 123 clades. Based on results from previous studies, we propose that PKSs in the same clade generally synthesize the same polyketide, which is structurally distinct from polyketides synthesized by PKSs in other clades. We predict that the 123 clades potentially produce 113 structurally distinct families of polyketide-derived NPs because some NPs (e.g., zearalenone) require two PKSs for their synthesis. Collectively, the clades include PKSs required for synthesis of six NPs whose production has not previously been reported in Fusarium, including two NPs with significant pharmaceutical interest: chaetoviridin and a statin. Our results highlight the NP diversity of Fusarium and the potential of the genus to produce metabolites with medical and other applications.

Dual-phase imaging of cardiac metabolism using hyperpolarized pyruvate.

PURPOSE: Previous cardiac imaging studies using hyperpolarized (HP) [1-13 C]pyruvate were acquired at end-diastole (ED). Little is known about the interaction between cardiac cycle and metabolite content in the myocardium. In this study, we compared images of HP pyruvate and products at end-systole (ES) and ED. METHODS: A dual-phase 13 C MRI sequence was implemented to acquire two sequential HP images within a single cardiac cycle at ES and ED during successive R-R intervals in an interleaved manner. Each healthy volunteer (N = 3) received two injections of HP [1-13 C]pyruvate for the dual-phase imaging on the short-axis and the vertical long-axis planes. Spatial distribution of HP 13 C metabolites at each cardiac phase was correlated to multiphase 1 H MRI to confirm the mechanical changes. Ratios of myocardial HP metabolites were compared between ES and ED. Segmental analysis was performed on the midcavity short-axis plane. RESULTS: In addition to mechanical changes, metabolic profiles of the heart detected by HP [1-13 C]pyruvate differed between ES and ED. The myocardial signal of [13 C]bicarbonate relative to [1-13 C]lactate was significantly smaller at ED than the ratio at ES (p < .05), particularly in mid-anterior and mid-inferoseptal segments. The distinct metabolic profiles in the myocardium likely reflect the technical aspects of the imaging approach such as the coronary flow in addition to the cyclical changes in metabolism. CONCLUSION: The study demonstrates that metabolic profiles of the heart, measured by HP [1-13 C]pyruvate, are affected by the cardiac cycle in which that the data are acquired.

Dynamic 13 C MR spectroscopy as an alternative to imaging for assessing cerebral metabolism using hyperpolarized pyruvate in humans.

PURPOSE: This study is to investigate time-resolved 13 C MR spectroscopy (MRS) as an alternative to imaging for assessing pyruvate metabolism using hyperpolarized (HP) [1-13 C]pyruvate in the human brain. METHODS: Time-resolved 13 C spectra were acquired from four axial brain slices of healthy human participants (n = 4) after a bolus injection of HP [1-13 C]pyruvate. 13 C MRS with low flip-angle excitations and a multichannel 13 C/1 H dual-frequency radiofrequency (RF) coil were exploited for reliable and unperturbed assessment of HP pyruvate metabolism. Slice-wise areas under the curve (AUCs) of 13 C-metabolites were measured and kinetic analysis was performed to estimate the production rates of lactate and HCO3- . Linear regression analysis between brain volumes and HP signals was performed. Region-focused pyruvate metabolism was estimated using coil-wise 13 C reconstruction. Reproducibility of HP pyruvate exams was presented by performing two consecutive injections with a 45-minutes interval. RESULTS: [1-13 C]Lactate relative to the total 13 C signal (tC) was 0.21-0.24 in all slices. [13 C] HCO3- /tC was 0.065-0.091. Apparent conversion rate constants from pyruvate to lactate and HCO3- were calculated as 0.014-0.018 s-1 and 0.0043-0.0056 s-1 , respectively. Pyruvate/tC and lactate/tC were in moderate linear relationships with fractional gray matter volume within each slice. White matter presented poor linear regression fit with HP signals, and moderate correlations of the fractional cerebrospinal fluid volume with pyruvate/tC and lactate/tC were measured. Measured HP signals were comparable between two consecutive exams with HP [1-13 C]pyruvate. CONCLUSIONS: Dynamic MRS in combination with multichannel RF coils is an affordable and reliable alternative to imaging methods in investigating cerebral metabolism using HP [1-13 C]pyruvate.

Impact of Locoregional Treatment on Survival in Young Patients with Early-Stage Breast Cancer undergoing Upfront Surgery.

BACKGROUND: Randomized, controlled trials comparing breast-conserving therapy (BCT) with mastectomy have demonstrated equivalent overall survival (OS), but recent observational studies have shown improved OS in patients undergoing BCT. These studies provide limited data on young patients who are traditionally offered mastectomy due to perceived higher disease risk. This study examines the OS in a contemporary series of young women with breast cancer undergoing upfront BCT compared with mastectomy. METHODS: Women ≤40 years old with primary invasive T1-T2, N0-N1 breast cancer were identified from the National Cancer Database between 2006 and 2016. Patient cohorts were based according to locoregional treatment: BCT, mastectomy alone (Mx), and mastectomy with radiotherapy (Mx/RT). Kaplan-Meier method followed by Cox proportional-hazards regression with inverse probability of treatment weighting (IPTW) were performed to account for treatment selection bias effects in OS. RESULTS: A total of 15,611 patients met the study criteria; 9,509 patients (60.9%) had BCT, 4,020 (25.8%) had Mx/RT, and 2,082 (13.3%) had Mx alone. The median follow-up was 4.6 years (interquartile range [IQR] 3.0-6.4). After IPTW-adjustment, the 5-year OS was similar for BCT (95%), Mx (95%), and Mx/RT (94%), and there was no significant difference in OS in Mx (hazard ratio [HR] = 1.16, 95% confidence interval [CI] 0.90-1.51) and Mx/RT (HR = 1.08, 95% CI 0.88-1.34) compared with BCT. Mx/RT was associated with decreased survival in patients with pT2N0 (HR = 1.78, 95% CI 1.12-2.84). CONCLUSIONS: Among young patients with early-stage breast cancer, overall survival was equivalent regardless of surgical approach. Breast-conserving therapy remains a safe option in young women despite the clinical tendency to offer upfront mastectomy in young patients.

Understanding the Dynamics of Cellulose Dissolved in an Ionic Liquid Solvent Under Shear and Extensional Flows.

Ionic liquids (ILs) hold great potential as solvents to dissolve, recycle, and regenerate cellulosic fabrics, but the dissolved cellulose material system requires greater study in conditions relevant to fiber spinning processes, especially characterization of nonlinear shear and extensional flows. To address this gap, we aimed to disentangle the effects of the temperature, cellulose concentration, and degree of polymerization (DOP) on the shear and extensional flows of cellulose dissolved in an IL. We have studied the behavior of cellulose from two sources, fabric and filter paper, dissolved in 1-ethyl-3-methylimidazolium acetate ([C2C1Im][OAc]) over a range of temperatures (25 to 80 °C) and concentrations (up to 4%) that cover both semidilute and entangled regimes. The linear viscoelastic (LVE) response was measured using small-amplitude oscillatory shear techniques, and the results were unified by reducing the temperature, concentration, and DOP onto a single master curve using time superposition techniques. The shear rheological data were further fitted to a fractional Maxwell liquid (FML) model and were found to satisfy the Cox-Merz rule within the measurement range. Meanwhile, the material response in the non-LVE (NLVE) regime at large strains and strain rates has special relevance for spinning processes. We quantified the NLVE behavior using steady shear flow tests alongside uniaxial extension using a customized capillary breakup extensional rheometer. The results for both shear and extensional NLVE responses were described by the Rolie-Poly model to account for flow-dependent relaxation times and nonmonotonic viscosity evolution with strain rates in an extensional flow, which primarily arise from complex polymer interactions at high concentrations. The physically interpretable model fitting parameters were further compared to describe differences in material response to different flow types at varying temperatures, concentrations, and DOP. Finally, the fitting parameters from the FML and Rolie-Poly models were connected under the same superposition framework to provide a comprehensive description within the wide measured parameter window for the flow and handling of cellulose in [C2C1Im][OAc] in both linear and nonlinear regimes.

Hyperpolarized 13C MR Spectroscopy Depicts in Vivo Effect of Exercise on Pyruvate Metabolism in Human Skeletal Muscle.

Background Pyruvate dehydrogenase (PDH) and lactate dehydrogenase are essential for adenosine triphosphate production in skeletal muscle. At the onset of exercise, oxidation of glucose and glycogen is quickly enabled by dephosphorylation of PDH. However, direct measurement of PDH flux in exercising human muscle is daunting, and the net effect of covalent modification and other control mechanisms on PDH flux has not been assessed. Purpose To demonstrate the feasibility of assessing PDH activation and changes in pyruvate metabolism in human skeletal muscle after the onset of exercise using carbon 13 (13C) MRI with hyperpolarized (HP) [1-13C]-pyruvate. Materials and Methods For this prospective study, sedentary adults in good general health (mean age, 42 years ± 18 [standard deviation]; six men) were recruited from August 2019 to September 2020. Subgroups of the participants were injected with HP [1-13C]-pyruvate at resting, during plantar flexion exercise, or 5 minutes after exercise during recovery. In parallel, hydrogen 1 arterial spin labeling MRI was performed to estimate muscle tissue perfusion. An unpaired t test was used for comparing 13C data among the states. Results At rest, HP [1-13C]-lactate and [1-13C]-alanine were detected in calf muscle, but [13C]-bicarbonate was negligible. During moderate flexion-extension exercise, total HP 13C signals (tC) increased 2.8-fold because of increased muscle perfusion (P = .005), and HP [1-13C]-lactate-to-tC ratio increased 1.7-fold (P = .04). HP [13C]-bicarbonate-to-tC ratio increased 8.4-fold (P = .002) and returned to the resting level 5 minutes after exercise, whereas the lactate-to-tC ratio continued to increase to 2.3-fold as compared with resting (P = .008). Conclusion Lactate and bicarbonate production from hyperpolarized (HP) [1-carbon 13 {13C}]-pyruvate in skeletal muscle rapidly reflected the onset and the termination of exercise. These results demonstrate the feasibility of imaging skeletal muscle metabolism using HP [1-13C]-pyruvate MRI and the sensitivity of in vivo pyruvate metabolism to exercise states. © RSNA, 2021 Online supplemental material is available for this article.

Cardiac T2∗ measurement of hyperpolarized 13 C metabolites using metabolite-selective multi-echo spiral imaging.

PURPOSE: Noninvasive imaging with hyperpolarized (HP) pyruvate can capture in vivo cardiac metabolism. For proper quantification of the metabolites and optimization of imaging parameters, understanding MR characteristics such as T2∗ s of the HP signals is critical. This study is to measure in vivo cardiac T2∗ s of HP [1-13 C]pyruvate and the products in rodents and humans. METHODS: A dynamic 13 C multi-echo spiral imaging sequence that acquires [13 C]bicarbonate, [1-13 C]lactate, and [1-13 C]pyruvate images in an interleaved manner was implemented for a clinical 3 Tesla system. T2∗ of each metabolite was calculated from the multi-echo images by fitting the signal decay of each region of interest mono-exponentially. The performance of measuring T2∗ using the sequence was first validated using a 13 C phantom and then with rodents following a bolus injection of HP [1-13 C]pyruvate. In humans, T2∗ of each metabolite was calculated for left ventricle, right ventricle, and myocardium. RESULTS: Cardiac T2∗ s of HP [1-13 C]pyruvate, [1-13 C]lactate, and [13 C]bicarbonate in rodents were measured as 24.9 ± 5.0, 16.4 ± 4.7, and 16.9 ± 3.4 ms, respectively. In humans, T2∗ of [1-13 C]pyruvate was 108.7 ± 22.6 ms in left ventricle and 129.4 ± 8.9 ms in right ventricle. T2∗ of [1-13 C]lactate was 40.9 ± 8.3, 44.2 ± 5.5, and 43.7 ± 9.0 ms in left ventricle, right ventricle, and myocardium, respectively. T2∗ of [13 C]bicarbonate in myocardium was 64.4 ± 2.5 ms. The measurements were reproducible and consistent over time after the pyruvate injection. CONCLUSION: The proposed metabolite-selective multi-echo spiral imaging sequence reliably measures in vivo cardiac T2∗ s of HP [1-13 C]pyruvate and products.

Characterization and compensation of f0 inhomogeneity artifact in spiral hyperpolarized 13 C imaging of the human heart.

PURPOSE: This study aimed to investigate the role of regional f0 inhomogeneity in spiral hyperpolarized 13 C image quality and to develop measures to alleviate these effects. METHODS: Field map correction of hyperpolarized 13 C cardiac imaging using spiral readouts was evaluated in healthy subjects. Spiral readouts with differing duration (26 and 45 ms) but similar resolution were compared with respect to off-resonance performance and image quality. An f0 map-based image correction based on the multifrequency interpolation (MFI) method was implemented and compared to correction using a global frequency shift alone. Estimation of an unknown frequency shift was performed by maximizing a sharpness objective based on the Sobel variance. The apparent full width half at maximum (FWHM) of the myocardial wall on [13 C]bicarbonate was used to estimate blur. RESULTS: Mean myocardial wall FWHM measurements were unchanged with the short readout pre-correction (14.1 ± 2.9 mm) and post-MFI correction (14.1 ± 3.4 mm), but significantly decreased in the long waveform (20.6 ± 6.6 mm uncorrected, 17.7 ± 7.0 corrected, P = .007). Bicarbonate signal-to-noise ratio (SNR) of the images acquired with the long waveform were increased by 1.4 ± 0.3 compared to those acquired with the short waveform (predicted 1.32). Improvement of image quality was observed for all metabolites with f0 correction. CONCLUSIONS: f0 -map correction reduced blur and recovered signal from dropouts, particularly along the posterior myocardial wall. The low image SNR of [13 C]bicarbonate can be compensated with longer duration readouts but at the expense of increased f0 artifacts, which can be partially corrected for with the proposed methods.