Hydroponic Growth of [13C]-Labeled Tobacco for DNA Damage Studies in Cigarette Smokers.

Cigarette smoking is the acknowledged major cause of cancers of the lung and oral cavity and is an established important risk factor for multiple other cancers. DNA addition products (DNA adducts) caused by cigarette smoking are critical factors in its mechanism of carcinogenesis. However, most DNA adducts detected to date in humans cannot be specifically ascribed to smoking but rather have multiple exogenous and endogenous sources. In the study reported here, we prepared [13C]-labeled tobacco to address this problem. We report for the first time the successful growth from seeds to flowering under hydroponic conditions of highly [13C]-labeled tobacco in a controlled 13CO2 environment. The standard growth procedure with optimized conditions is described in detail. The [13C]-enrichment rate was assessed by quantifying nicotine and sugars and their [13C]-isotopologues in this tobacco using high-resolution mass spectrometry, reaching >94% in the tobacco leaves. The [13C]-labeled leaves after curing will be used to make cigarettes, allowing investigation of the specific contributions of tobacco smoke carcinogens to identified DNA adducts in smokers.

Incidence and mortality trends of primary cutaneous melanoma: A 50-year Rochester Epidemiologic Project study.

Background: National cancer reporting-based registry data, although robust, lacks granularity for incidence trends. Expert opinion remains conflicted regarding the possibility of melanoma overdiagnosis in the context of rising incidence without a corresponding rise in mortality. Objective: To characterize 10- and 50-year trends in melanoma incidence and mortality. Methods: Multicenter, population-based epidemiologic study utilizing the Rochester Epidemiology Project for Olmsted County, Minnesota residents diagnosed with melanoma from 01/01/1970 to 12/21/2020. Age- and sex-adjusted incidence and disease-specific mortality are calculated. Results: Two thousand three hundred ten primary cutaneous melanomas were identified. Current age- and sex-adjusted incidence rates increased 11.1-fold since 1970s (P < .001). Over the last decade, there is an overall 1.21-fold (P < .002) increase, with a 1.36-fold increase (P < .002) among females and no significant increase among males (1.09-fold increase, P < .329). Melanoma-specific mortality decreased from 26.7% in 1970s to 1.5% in 2010s, with a hazard ratio (HR) reduction of 0.73 (P < .001) per 5-year period. Increased mortality was associated with Breslow thickness (HR 1.35, P < .001), age at diagnosis (HR 1.13, P = .001) left anatomic site (HR 1.98, P = .016), and nodular histogenic subtype (HR 3.08, P < .001). Limitations: Retrospective nature and focused geographic investigation. Conclusion: Melanoma incidence has continued to increase over the past decade, most significantly in females aged 40+. Trend variations among age and sex cohorts suggests external factors beyond overdiagnosis may be responsible. Disease-specific mortality of melanoma continues to decrease over the last 50 years.

Skeletal muscle quantity and quality evaluation in heart failure: comparing thoracic versus abdominopelvic CT approaches.

Given the critical role of skeletal muscle in healthy aging, low muscle mass (myopenia) and quality (myosteatosis) can be used as predictors of poor functional and cardiometabolic outcomes. Myopenia is also a part of sarcopenia and malnutrition diagnostic criteria. However, there is limited evidence for using chest computed tomography (CT) to evaluate muscle health. We aimed to compare chest CT landmarks to the widely used L3 vertebra for single-slice skeletal muscle evaluation in patients with heart failure (HF). Patients admitted for acute decompensated HF between January 2017 and December 2018 were retrospectively analyzed. Body composition measurements were made on CT of the chest and abdomen/pelvis with or without contrast one month before discharge. Skeletal muscle index (SMI) and intermuscular adipose tissue percentage (IMAT%) were calculated at several thoracic levels (above the aortic arch, T8, and T12) and correlated to the widely used L3 level. A total of 200 patients were included, 89 (44.5%) female. The strongest correlation of thoracic SMI (for muscle quantity) and IMAT% (for muscle quality) with L3 was at the T12 level (r = 0.834, p < 0.001 and r = 0.757, p < 0.001, respectively). Cutoffs to identify low muscle mass for T12 SMI (derived from the lowest sex-stratified L3 SMI tertile) were 31.1 cm²/m² in men and 26.3 cm²/m² in women. SMI and IMAT% at T12 had excellent correlations with the widely used L3 level for muscle quantity and quality evaluation in patients with HF.

Impact of therapeutic inhibition of oncogenic cell signaling tyrosine kinase on cell metabolism: in vivo-detectable metabolic biomarkers of inhibition.

BACKGROUND: Inhibition of kinases is the ever-expanding therapeutic approach to various types of cancer. Typically, assessment of the treatment response is accomplished by standard, volumetric imaging procedures, performed weeks to months after the onset of treatment, given the predominantly cytostatic nature of the kinase inhibitors, at least when used as single agents. Therefore, there is a great clinical need to develop new monitoring approaches to detect the response to kinase inhibition much more promptly. Noninvasive 1H magnetic resonance spectroscopy (MRS) can measure in vitro and in vivo concentration of key metabolites which may potentially serve as biomarkers of response to kinase inhibition. METHODS: We employed mantle cell lymphoma (MCL) cell lines demonstrating markedly diverse sensitivity of inhibition of Bruton's tyrosine kinase (BTK) regarding their growth and studied in-depth effects of the inhibition on various aspects of cell metabolism including metabolite synthesis using metabolomics, glucose and oxidative metabolism by Seahorse XF technology, and concentration of index metabolites lactate, alanine, total choline and taurine by 1H MRS. RESULTS: Effective BTK inhibition profoundly suppressed key cell metabolic pathways, foremost pyrimidine and purine synthesis, the citrate (TCA) cycle, glycolysis, and pyruvate and glutamine/alanine metabolism. It also inhibited glycolysis and amino acid-related oxidative metabolism. Finally, it profoundly and quickly decreased concentration of lactate (a product of mainly glycolysis) and alanine (an indicator of amino acid metabolism) and, less universally total choline both in vitro and in vivo, in the MCL xenotransplant model. The decrease correlated directly with the degree of inhibition of lymphoma cell expansion and tumor growth. CONCLUSIONS: Our results indicate that BTK inhibition exerts a broad and profound suppressive effect on cell metabolism and that the affected index metabolites such as lactate, alanine may serve as early, sensitive, and reliable biomarkers of inhibition in lymphoma patients detectable by noninvasive MRS-based imaging method. This kind of imaging-based detection may also be applicable to other kinase inhibitors, as well as diverse lymphoid and non-lymphoid malignancies.

Predictors of developing renal dysfunction following diagnosis of transthyretin cardiac amyloidosis.

BACKGROUND: In patients with transthyretin cardiac amyloidosis (ATTR-CA), renal dysfunction is a poor prognostic indicator. Limited data are available on variables that portend worsening renal function (wRF) among ATTR-CA patients. OBJECTIVES: This study assesses which characteristics place patients at higher risk for the development of wRF (defined as a drop of ≥10% in glomerular filtration rate [GFR]) within the first year following diagnosis of ATTR-CA. METHODS: We included patients with ATTR-CA (n = 134) evaluated between 2/2016 and 12/2022 and followed for up to 1 year at our amyloid clinic. Patients were stratified into two groups: a group with maintained renal function (mRF) and a group with wRF and compared using appropriate testing. Significant variables in the univariate analysis were included in the multivariable logistic regression model to determine characteristics associated with wRF. RESULTS: Within a follow-up period of 326 ± 118 days, the median GFR% change measured -6% [-18%, +8]. About 41.8% (n = 56) had wRF, while the remainder had mRF. In addition, in patients with no prior history of chronic kidney disease (CKD), 25.5% developed de novo CKD. On multivariable logistic regression, only New York Heart Association (NYHA) class ≥III (odds ratio [OR]: 3.9, 95% confidence interval [CI]: [1.6-9.3]), history of ischemic heart disease (IHD) (OR: 0.3, 95% CI: [0.1-0.7]), and not receiving SGLT-2i (OR: 0.1, 95% CI: [0.02-0.5]) were significant predictors of wRF. CONCLUSION: Our study demonstrated that the development of de novo renal dysfunction or wRF is common following the diagnosis of ATTR-CA. Additionally, we identified worse NYHA class and no prior history of IHD as significant predictors associated with developing wRF, while receiving SGLT-2i therapy appeared to be protective in this population.

Combining potential and realized distribution modeling of telemetry data for a bycatch risk assessment.

Establishing marine species distributions is essential for guiding management and can be estimated by identifying potential favorable habitat at a population level and incorporating individual-level information (e.g., movement constraints) to inform realized space use. In this research, we applied a combined modeling approach to tracking data of adult female and juvenile South American sea lions (Otaria flavescens; n = 9) from July to November 2011 to make habitat predictions for populations in northern Chile. We incorporated topographic and oceanographic predictors with sea lion locations and environmentally based pseudo-absences in a generalized linear model for estimating population-level distribution. For the individual approach, we used a generalized linear mixed-effects model with a negative exponential kernel variable to quantify distance-dependent movement from the colony. Spatial predictions from both approaches were combined in a bivariate color map to identify areas of agreement. We then used a GIS-based risk model to characterize bycatch risk in industrial and artisanal purse-seine fisheries based on fishing set data from scientific observers and artisanal fleet logs (2010-2015), the bivariate sea lion distribution map, and criteria ratings of interaction characteristics. Our results indicate population-level associations with productive, shallow, low slope waters, near to river-mouths, and with high eddy activity. Individual distribution was restricted to shallow slopes and cool waters. Variation between approaches may reflect intrinsic factors restricting use of otherwise favorable habitat; however, sample size was limited, and additional data are needed to establish the full range of individual-level distributions. Our bycatch risk outputs identified highest risk from industrial fisheries operating nearshore (within 5 NM) and risk was lower, overall, for the artisanal fleet. This research demonstrates the potential for integrating potential and realized distribution models within a spatial risk assessment and fills a gap in knowledge on this species' distribution, providing a basis for targeting bycatch mitigation outreach and interventions.

Analytical methods for stable isotope labeling to elucidate rapid auxin kinetics in Arabidopsis thaliana.

The phytohormone auxin plays a critical role in plant growth and development. Despite significant progress in elucidating metabolic pathways of the primary bioactive auxin, indole-3-acetic acid (IAA), over the past few decades, key components such as intermediates and enzymes have not been fully characterized, and the dynamic regulation of IAA metabolism in response to environmental signals has not been completely revealed. In this study, we established a protocol employing a highly sensitive liquid chromatography-mass spectrometry (LC-MS) instrumentation and a rapid stable isotope labeling approach. We treated Arabidopsis seedlings with two stable isotope labeled precursors ([13C6]anthranilate and [13C8, 15N1]indole) and monitored the label incorporation into proposed indolic compounds involved in IAA biosynthetic pathways. This Stable Isotope Labeled Kinetics (SILK) method allowed us to trace the turnover rates of IAA pathway precursors and product concurrently with a time scale of seconds to minutes. By measuring the entire pathways over time and using different isotopic tracer techniques, we demonstrated that these methods offer more detailed information about this complex interacting network of IAA biosynthesis, and should prove to be useful for studying auxin metabolic network in vivo in a variety of plant tissues and under different environmental conditions.

The Impact of Surgical Delay in Primary Cutaneous Melanoma: A Systematic Review.

BACKGROUND AND OBJECTIVES: The prognosis of patients diagnosed with melanoma is highly dependent on staging, early detection, and early intervention. In this systematic review, the authors aimed to investigate the impact of surgical delay (time between diagnostic biopsy and definitive surgical excision) on melanoma-specific outcomes. MATERIAL AND METHODS: A systematic review was conducted from Embase (1974-present), MEDLINE (1946-present), Cochrane Central Register of Controlled Trials (2005-present), Scopus, and Web of Science. A total of 977 studies were included for review after removal of duplicates. A total of 10 studies were included for final analysis. RESULTS: In total, 70% (7/10) of the studies found that longer wait times between initial biopsy and surgical intervention are correlated with lower overall survival. Among the 9 studies that reported overall survival as a percentage, the median and SD overall survival was 82% ± 5.87. CONCLUSION: There is evidence that prolonged surgical delay in patients diagnosed with Stage I cutaneous melanoma is associated with worsened overall mortality, whereas the effect of surgical delay on overall mortality in Stages II and III melanomas is uncertain. Future prospective studies and randomized clinical trials are needed to better define the appropriate surgical wait times between biopsy and surgical treatment.

Relationship of Age and Gender to Motility Test Results and Symptoms in Patients with Chronic Constipation.

BACKGROUND/AIMS: Patients with chronic constipation (CC) exhibit symptoms and functional abnormalities upon testing, but their relationship to age and gender is unclear. We assessed age- and gender-related differences in symptoms, colon transit time, and anorectal motility, sensation, and expulsion. PATIENTS AND METHODS: Retrospective, post hoc data analysis of patients with CC, who underwent Wireless Motility Capsule (WMC), High-Resolution Anorectal Manometry (HR-ARM), Balloon Expulsion Test (BET) and Rectal Sensory Testing (RST). Clinical assessment was made by questionnaires. Standard WMC criteria for colonic transit time (CTT) and the London classification was used for HR-ARM analyses, and regression plots between age, gender, CTT, HR-HRM, RST and BET were calculated. RESULTS: We studied 75 women and 91 men. Abdominal pain, infrequent defecation, incomplete evacuation, defecatory straining, and multiple motility and anorectal function abnormalities were common. Abdominal pain was least frequently, and straining was most frequently associated with a motility abnormality. For each symptom, the highest prevalence was associated with failed BET. There was a significant increase in CTT with age only in men (p = 0.0006). In men, for each year of age there was a CTT increase of 1.02 h. The prevalence of abdominal pain and incomplete evacuation for females was significantly higher than that for males (both P < 0.05). The prevalence of low anal squeeze pressure for females was significantly higher than that for males, and the prevalence of poor rectal sensation for males was significantly higher than that for females (both P < 0.05). A significant decrease in basal anal and squeeze pressures with age occurred in women (p < 0.0001); an increase in age of one year was associated with a decrease in anal base pressure of 1.2 mmHg. Abnormal CTT and HR-ARM tests were associated with increased symptom frequency, but not severity. CONCLUSIONS: There are significant age- and gender-related differences in symptoms, CTT, and HR-HRM parameters, rectal sensation, and expulsion, that may influence the multifaceted management of constipation.

Disparities Between Teleretinal Imaging Findings and Patient-Reported Diabetic Retinopathy Status and Follow-up Eye Care Interval: A 10-Year Prospective Study.

OBJECTIVE: To assess self-reported awareness of diabetic retinopathy (DR) and concordance of eye examination follow-up compared with findings from concurrent retinal images. RESEARCH DESIGN AND METHODS: We conducted a prospective observational 10-year study of 26,876 consecutive patients with diabetes who underwent retinal imaging during an endocrinology visit. Awareness and concordance were evaluated using questionnaires and retinal imaging. RESULTS: Awareness information and gradable images were available in 25,360 patients (94.3%). Severity of DR by imaging was as follows: no DR (n = 14,317; 56.5%), mild DR (n = 6,805; 26.8%), or vision-threatening DR (vtDR; n = 4,238; 16.7%). In the no, mild, and vtDR groups, 96.7%, 88.5%, and 54.9% of patients, respectively, reported being unaware of any prior DR. When DR was present, reporting no prior DR was associated with shorter diabetes duration, milder DR, last eye examination >1 year before, no dilation, no scheduled appointment, and less specialized provider (all P < 0.001). Among patients with vtDR, 41.2%, 58.1%, and 64.2% did not report being aware of any DR and follow-up was concordant with current DR severity in 66.7%, 41.3%, and 25.4% (P < 0.001) of patients when prior examination was performed by a retinal specialist, nonretinal ophthalmologist, or optometrist (P < 0.001), respectively. CONCLUSIONS: Substantial discrepancies exist between DR presence, patient awareness, and concordance of follow-up across all DR severity levels. These discrepancies are present across all eye care provider types, with the magnitude influenced by provider type. Therefore, patient self-report should not be relied upon to reflect DR status. Modification of medical care and education models may be necessary to enhance retention of ophthalmic knowledge in patients with diabetes and ensure accurate communication between all health care providers.

Intraoperative Immunohistochemistry During Mohs Micrographic Surgery and Staged Excision Decreases Local Recurrence Rates for Invasive Cutaneous Melanoma: A Systematic Review and Meta-Analysis.

BACKGROUND: Mohs micrographic surgery (MMS) is increasingly used to treat cutaneous melanoma. However, it is unclear whether intraoperative immunohistochemistry (IHC) improves surgical outcomes. OBJECTIVE: To determine whether intraoperative IHC during MMS and staged excision is associated with a decreased risk of poor surgical outcomes. MATERIALS AND METHODS: Search of 6 databases identified comparative and noncomparative studies that reported local recurrence after MMS or staged excision with or without IHC for melanoma. Random-effects meta-analysis was used to estimate pooled local recurrence rates, nodal recurrence, distant recurrence, and disease-specific mortality. RESULTS: Overall, 57 studies representing 12,043 patients with cutaneous melanoma and 12,590 tumors met inclusion criteria. Combined MMS and staged excision with IHC was associated with decreased local recurrence in patients with invasive melanoma (0.3%, 95% CI: 0-0.6) versus hematoxylin and eosin alone (1.8%, 95% CI: 0.8%-2.8%) [ p < .001]. Secondary outcomes including nodal recurrence, distant recurrence, and disease-specific mortality were not significantly different between these 2 groups. Study heterogeneity was moderately-high. CONCLUSION: Local recurrence of invasive melanoma is significantly lower after MMS and staged excision with IHC as opposed to without IHC. These findings suggest that the use of intraoperative IHC during MMS or staged excision should strongly be considered, particularly for invasive melanoma.Trial Registration PROSPERO Identifier: CRD42023435630.

A perspective on three sustainable hydrogen production technologies with a focus on technology readiness level, cost of production and life cycle environmental impacts.

Hydrogen will play an indispensable role as both an energy vector and as a molecule in essential products in the transition to climate neutrality. However, the optimal sustainable hydrogen production system is not definitive due to challenges in energy conversion efficiency, economic cost, and associated marginal abatement cost. This review summarises and contrasts different sustainable hydrogen production technologies including for their development, potential for improvement, barriers to large-scale industrial application, capital and operating cost, and life-cycle environmental impact. Polymer electrolyte membrane water electrolysis technology shows significant potential for large-scale application in the near-term, with a higher technology readiness level (expected to be 9 by 2030) and a levelized cost of hydrogen expected to be 4.15-6 €/kg H2 in 2030; this equates to a 50% decrease as compared to 2020. The four-step copper-chlorine (Cu-Cl) water thermochemical cycle can perform better in terms of life cycle environmental impact than the three- and five-step Cu-Cl cycle, however, due to system complexity and high capital expenditure, the thermochemical cycle is more suitable for long-term application should the technology develop. Biological conversion technologies (such as photo/dark fermentation) are at a lower technology readiness level, and the system efficiency of some of these pathways such as biophotolysis is low (less than 10%). Biomass gasification may be a more mature technology than some biological conversion pathways owing to its higher system efficiency (40%-50%). Biological conversion systems also have higher costs and as such require significant development to be comparable to hydrogen produced via electrolysis.

Cost-effectiveness analysis of margin-controlled surgery for vulvar Paget's disease.

Objectives: To determine the cost of two surgical treatment approaches for vulvar Paget's disease and model the cost-effectiveness considering differences in recurrence and reoperation over time. Methods: We assessed cost-effectiveness between excision guided by Mohs micrographic surgery (MMS-E) and traditional wide local excision (WLE). We examined billing data from patients with vulvar Paget's disease who underwent MMS-E (cases, n = 24, 2018-2022) or WLE (controls, n = 64, 1990-2020). We created typical treatment bundles incorporating physician-administered services and facility costs standardized to Medicare reimbursements in 2022 United States Dollars (USD). The primary measure of effectiveness was disease-free years of life. A secondary analysis estimated quality-adjusted life years (QALY). A Markov model simulated treatment pathways over a 10-year time horizon. Transition probabilities were based on institutional recurrence rates (3-year RR 6.7 % for MMS-E vs 34.1 % for WLE). We used a willingness-to-pay threshold of 100,000 USD per QALY. Results: The cost of a single surgical episode was 34,664 USD for MMS-E and 14,969 USD for WLE. In the setting of lower recurrence rates with MMS-E, the incremental cost was 12,789 USD per disease-free year gained. A secondary analysis incorporating QALY showed an incremental cost of 72,820 USD per QALY. Conclusions: MMS-E appears to be a cost-effective treatment for vulvar Paget's disease compared to historic standard of care. Our ability to estimate quality of life gained by avoiding disease recurrence was limited by scant data for this rare condition; thus, future studies incorporating health utility values are needed to facilitate a more comprehensive analysis.

Automated Machine Learning for Predicting Diabetic Retinopathy Progression From Ultra-Widefield Retinal Images.

Importance: Machine learning (ML) algorithms have the potential to identify eyes with early diabetic retinopathy (DR) at increased risk for disease progression. Objective: To create and validate automated ML models (autoML) for DR progression from ultra-widefield (UWF) retinal images. Design, Setting and Participants: Deidentified UWF images with mild or moderate nonproliferative DR (NPDR) with 3 years of longitudinal follow-up retinal imaging or evidence of progression within 3 years were used to develop automated ML models for predicting DR progression in UWF images. All images were collected from a tertiary diabetes-specific medical center retinal image dataset. Data were collected from July to September 2022. Exposure: Automated ML models were generated from baseline on-axis 200° UWF retinal images. Baseline retinal images were labeled for progression based on centralized reading center evaluation of baseline and follow-up images according to the clinical Early Treatment Diabetic Retinopathy Study severity scale. Images for model development were split 8-1-1 for training, optimization, and testing to detect 1 or more steps of DR progression. Validation was performed using a 328-image set from the same patient population not used in model development. Main Outcomes and Measures: Area under the precision-recall curve (AUPRC), sensitivity, specificity, and accuracy. Results: A total of 1179 deidentified UWF images with mild (380 [32.2%]) or moderate (799 [67.8%]) NPDR were included. DR progression was present in half of the training set (590 of 1179 [50.0%]). The model's AUPRC was 0.717 for baseline mild NPDR and 0.863 for moderate NPDR. On the validation set for eyes with mild NPDR, sensitivity was 0.72 (95% CI, 0.57-0.83), specificity was 0.63 (95% CI, 0.57-0.69), prevalence was 0.15 (95% CI, 0.12-0.20), and accuracy was 64.3%; for eyes with moderate NPDR, sensitivity was 0.80 (95% CI, 0.70-0.87), specificity was 0.72 (95% CI, 0.66-0.76), prevalence was 0.22 (95% CI, 0.19-0.27), and accuracy was 73.8%. In the validation set, 6 of 9 eyes (75%) with mild NPDR and 35 of 41 eyes (85%) with moderate NPDR progressed 2 steps or more were identified. All 4 eyes with mild NPDR that progressed within 6 months and 1 year were identified, and 8 of 9 (89%) and 17 of 20 (85%) with moderate NPDR that progressed within 6 months and 1 year, respectively, were identified. Conclusions and Relevance: This study demonstrates the accuracy and feasibility of automated ML models for identifying DR progression developed using UWF images, especially for prediction of 2-step or greater DR progression within 1 year. Potentially, the use of ML algorithms may refine the risk of disease progression and identify those at highest short-term risk, thus reducing costs and improving vision-related outcomes.

Disease-Specific Mortality of Dermatofibrosarcoma Protuberans After Mohs Surgery Versus Wide Local Excision: A Systematic Review and Meta-Analysis.

BACKGROUND: Although advances have been made in the understanding of recurrence patterns in dermatofibrosarcoma protuberans, the current understanding of disease-specific mortality after surgical management is limited. OBJECTIVE: To understand disease-specific mortality rates associated with dermatofibrosarcoma protuberans treated with wide local excision (WLE) versus Mohs micrographic surgery (MMS). MATERIALS AND METHODS: A systematic literature search was conducted on March 6, 2023, to identify patients treated with MMS or WLE for dermatofibrosarcoma protuberans. RESULTS: A total of 136 studies met inclusion criteria. Overall, the disease-specific mortality rate was not significantly different after treatment with MMS (0.7%, confidence interval [CI] 0.1-1.2, p : 0.016) versus WLE (0.9%, CI 0.6-1.2, p < .001). For recurrent tumors, the MMS treatment group had a statistically significantly lower disease-specific mortality rate (1.0%, CI 0.0-2.0, p 0.046) compared with the WLE treatment group (3.5%, CI 2.0-5.1, p < .001). The mean follow-up for all studies was 57.6 months. CONCLUSION AND RELEVANCE: The authors' meta-analysis suggests there is no substantial difference in disease-specific mortality between MMS and WLE in patients with dermatofibrosarcoma protuberans, except in the case of recurrent tumors, where MMS seems to confer a survival advantage.

An auxin research odyssey: 1989-2023.

The phytohormone auxin is at times called the master regulator of plant processes and has been shown to be a central player in embryo development, the establishment of the polar axis, early aspects of seedling growth, as well as growth and organ formation during later stages of plant development. The Plant Cell has been key, since the inception of the journal, to developing an understanding of auxin biology. Auxin-regulated plant growth control is accomplished by both changes in the levels of active hormones and the sensitivity of plant tissues to these concentration changes. In this historical review, we chart auxin research as it has progressed in key areas and highlight the role The Plant Cell played in these scientific developments. We focus on understanding auxin-responsive genes, transcription factors, reporter constructs, perception, and signal transduction processes. Auxin metabolism is discussed from the development of tryptophan auxotrophic mutants, the molecular biology of conjugate formation and hydrolysis, indole-3-butyric acid metabolism and transport, and key steps in indole-3-acetic acid biosynthesis, catabolism, and transport. This progress leads to an expectation of a more comprehensive understanding of the systems biology of auxin and the spatial and temporal regulation of cellular growth and development.

Metabolic Imaging Biomarkers of Response to Signaling Inhibition Therapy in Melanoma.

Dabrafenib therapy for metastatic melanoma focuses on blocking growth-promoting signals produced by a hyperactive BRAF protein. We report the metabolic differences of four human melanoma cell lines with diverse responses to dabrafenib therapy (30 mg/kg; oral): WM3918 < WM9838BR < WM983B < DB-1. Our goal was to determine if metabolic changes produced by the altered signaling pathway due to BRAF mutations differ in the melanoma models and whether these differences correlate with response to treatment. We assessed metabolic changes in isolated cells using high-resolution proton magnetic resonance spectroscopy (1H MRS) and supplementary biochemical assays. We also noninvasively studied mouse xenografts using proton and phosphorus (1H/31P) MRS. We found consistent changes in lactate and alanine, either in isolated cells or mouse xenografts, correlating with their relative dabrafenib responsiveness. In xenografts, we also observed that a more significant response to dabrafenib correlated with higher bioenergetics (i.e., increased ßNTP/Pi). Notably, our noninvasive assessment of the metabolic status of the human melanoma xenografts by 1H/31P MRS demonstrated early metabolite changes preceding therapy response (i.e., tumor shrinkage). Therefore, this noninvasive methodology could be translated to assess in vivo predictive metabolic biomarkers of response in melanoma patients under dabrafenib and probably other signaling inhibition therapies.